The maximum angle of the cardan transmission. Determination of the allowable force acting on the needle bearing. Cardan transmission with joints of unequal angular speeds

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Introduction 3

1. Design overview 5

1.1. Basic requirements for cardan transmissions and their classification. five

1.2. Cardan transmission with unequal hinges angular velocities 8

1.3. Cardan drives with constant velocity joints. fifteen

1.4. Materials of the main parts of the driveline 26

1.5. Prototype Selection 26

2. Checking calculation of the cardan drive of the GAZ-2410 car 28

2.1. Load modes 28

2.2. Determination of torsional stress and torsion angle cardan shaft 29

2.3. Determination of the axial force acting on cardan shaft 30

2.4. Estimation of non-uniformity of rotation and inertial moment 31

2.5. Calculation of the universal joint cross 35

2.6. Calculation of the universal joint forks 37

2.7. Determination of the permissible force acting on the needle bearing 39

2.8. Calculation of the critical number of revolutions of the propeller shaft 40

2.9. Thermal calculation of the universal joint 41

Conclusion 47

Literature 49

Perform a check calculation of the cardan drive of the GAZ-2410 "Volga" car with an increase in the transmitted torque by 1.5 times.

Introduction

The car plays an important role in human life. Almost from the moment of its invention, it immediately took one of the leading places in the national economy. The automotive industry is developing at a very fast pace. The most advanced technologies are used in the production of cars.

It should be noted that a characteristic feature of car production, especially in recent years, is its orientation towards a specific consumer. Due to this, a large number of modifications of the same basic model appear, differing in a small number of parameters. This tendency is especially manifested in foreign companies, where the buyer can determine the complete set of the car. This is not typical for the domestic automobile industry, and especially for the production of passenger cars. Although many "families" of cars have appeared recently (as, for example, at the Volga Automobile Building Plant), a significant number of old models remain. Under these conditions, "alteration" of machines becomes urgent. The owner independently makes changes to the design of the car, trying to adapt it as much as possible to the operating conditions. This can be a change in the type of body, the installation of a new unit to replace an old one that has exhausted its resource and which differs from the latter in a number of indicators, etc. Changes to the original design of the car entails a change in operating modes, loads on its component parts. The new working conditions will differ from those that were determined during the design of the vehicle. Therefore, there is a need to check the performance of vehicle units in these new modes.

The purpose of this work is to perform a check calculation of the cardan transmission of the GAZ-2410 car with an increase in the transmitted torque. The increase in transmitted torque can be explained by installing a different gearbox with higher gear ratios or installing a new engine. The latter is often encountered in practice. The old engine could fully deplete its resource and a new one with higher characteristics could be installed in its place. The need for the engine to develop more torque may be caused by the need to overcome more resistance while driving (operating a car with increased load due to body re-equipment, the use of a non-standard trailer, etc.), the desire to improve acceleration characteristics. In case of significant changes in the characteristics of the engine, it is necessary to check the operability of the cardan transmission in the new operating conditions, since, according to its parameters, it may not be able to transmit increased torque. In this case, changes in its design will be required.

The purpose of the work is not only to check the efficiency of the cardan transmission with an increase in the transmitted torque and to propose changes in its design in case of unsatisfactory results. An analysis of existing structures is also carried out, which assumes a detailed and in-depth acquaintance with units, units that are similar in design to the design object, with the latest achievements in this area, with the prospects for the development of the structures under consideration. It is also important to master and practice the methods of verification calculations of units, car systems when operating conditions change, which can be used in further activities.

1. Overview of designs

Cardan drives are used in transmissions of cars for power communication of mechanisms, the shafts of which are not coaxial or are located at an angle, and their relative position can change during movement. Cardan drives are also used to drive auxiliary mechanisms, such as a winch. Sometimes the steering wheel is connected to the steering mechanism with the help of a cardan transmission. The cardan transmission consists of three main elements: cardan joints, oxen and their supports.

1.1. Basic requirements for cardan transmissions and their classification.

The following basic requirements are imposed on cardan gears (KP):

transmission of torque without generating additional loads in transmission (bending, twisting, vibrating, axial);

the ability to transmit torque while ensuring equality of the angular speeds of the driving and driven shafts, regardless of the angle between the connected shafts;

That is, the pinion shaft 506 is considered balanced about its main axis. that when the moment around the gear shaft 506 is zero, the constant resulting vector force rotates radially around the main shaft at the angular velocity of the main shafts. The analysis of the inertia force of the main shaft 508 is performed in two planes. The first step in resolving the inertial forces of the main shaft is to transfer all the resulting forces of the gear shaft 506 to points 536 with a double travel force, and these forces will act on the main shaft 508 in equal amounts, but in opposite directions, when all the forces and the moments acting on the main shaft 508 in the center 512 of the main bearing 514 in two planes are zero, the main shaft can be considered balanced both statically and dynamically.

high efficiency;

noiselessness;

general requirements for component parts transmissions - reliable transmission of torque, minimum moment of inertia, good heat dissipation from friction surfaces.

To meet these requirements in different operating conditions for different vehicles, there are different schemes of cardan drives.

Closed cardan transmissions. For vehicles in which the reaction moment on the rear axle is taken up by the pipe, the cardan drive is placed inside the pipe. Sometimes this tube also serves to transmit pushing forces. Since the length of the propeller shaft in this design does not change with relative movements of the body and the rear axle, there is no compensating (telescopic) connection in this type of propeller shaft and only one propeller joint is used. In this case, the uneven rotation of the propeller shaft is to some extent compensated by its elasticity. The scheme of such a transmission is shown in Figure 1, a. There are designs passenger cars, in which the connection between the gearbox and the main transmission is carried out by a torsion shaft, and there are no cardan joints. This is possible on vehicles where the main gear is installed in the back (Volvo-600). However, the above-described designs of cardan drives are not common.

Open cardan drives. (Figure 1, b) For cars in which the reactive moment is perceived by springs or jet rods, the cardan transmission must have at least two hinges and an compensating connection, since the distance between the hinges changes during movement. Two-, three- and multi-hinge gears are used (the latter are relatively rare). On long-wheelbase vehicles with a large distance between the units, cardan drives are used, consisting of two shafts - the intermediate and the main. This is necessary due to the fact that the use of one long shaft can lead to dangerous lateral vibrations, as a result of the coincidence of its critical angular velocity with the operational one. The stub shaft has a higher critical speed. Intermediate shaft installed on an intermediate support, which must have some elasticity. This is necessary for the reason that the power unit of the car (engine, clutch, gearbox), mounted on elastic cushions, has some freedom both in the vertical and horizontal planes. On some cars, intermediate supports with bearings rigidly installed in the housing are used, but the housing itself in this case can swing on the trunnions, which are connected with the bracket fixed to the frame cross member.

By kinematics, cardan joints of unequal (asynchronous) and equal angular velocities (SHRUS) are distinguished. Unequal angular velocity joints are used in gears when the driven shaft is tilted at an angle of no more than 20. Asynchronous universal joints with an intermediate cross are widely used. There are also universal asynchronous cardan joints, which differ from simple ones in that axial compensation is carried out in them in the joint mechanism itself, and not in the spline connection. Cardan joints of equal angular velocities are used in the drive of driving and simultaneously steered wheels of a car, the angle of inclination of the driven shaft, depending on the design of the hinge, can reach 45. Some CV joints are also made universal, with a compensating device inside the mechanism.

Along with cardan joints, semi-cardan joints are also used. Elastic semi-cardan joints are installed mainly in cardan drives of passenger cars, and depending on the design, the angle of inclination of the shaft can be from 8 to 10. Rigid semi-cardan hinges are used to compensate for inaccuracies in the installation of the connected mechanisms in cases where the latter are installed on an insufficiently rigid base. They are gear couplings... Shaft inclination angle no more than 2 не.

The general classification scheme for cardan joints is shown in Figure 2.

1.2. Cardan transmission with joints of unequal angular speeds

Figure: 3 Diagram of the universal joint

ardan hinges are called articulations, with the help of which rotation is transmitted from one shaft to another with a varying angle of inclination between the shafts.

The cardan joint of unequal angular velocities (Fig. 3) consists of a driving 2 and driven 4 forks pivotally connected to each other by a cross 3. The driving fork is rigidly connected to the drive shaft 1, and the driven fork is rigidly connected to the driven shaft 6 (rigidly or using a movable spline connection 5 to change its length). The torque from shaft 1 to shaft 6, the axes of which are located at an angle , the hinge transmits as a result of the rotation of the driven fork relative to b-B axis and crosses regarding a-A axis... However, the driven shaft rotates unevenly - with acceleration and deceleration. As a result, additional dynamic loads can arise in the transmission, sometimes exceeding the transmitted torque.

Wide application in cardan drives domestic cars got rigid simple universal joints on needle bearings. Such a hinge consists of two steel forks and a crosspiece with needle bearings connecting the fork with a pivot (Figure 4). Steel cups 13 with needle bearings 12 are installed on the carefully machined pins of the crosspiece 3. The bearing needles from the inner end rest on the support washer 11. The bowl is sealed on the crosspiece with a rubber gland 10 installed in the metal body 9, which is put on the crosspiece. The crosspiece with glasses is fixed in the ears of the forks 2 and 4 with retaining rings or plates 6 with screws. The cross-piece bearings are lubricated through the central oiler 7, from which oil goes to the bearings through the channels in the cross-piece. To eliminate excessive oil pressure, a body with a safety valve 8 is threaded into the crosspiece.

Cardan joints on needle bearings are used of an open type and are usually not covered with protective covers. On some vehicles, the cardan joint is equipped with a protective cap that covers it, eliminating contamination. Also, at present, a number of cars use cardan joints that do not require frequent periodic lubrication during operation. They use a grease that is held in place by a reliable gland seal. Grease is put into cups with needle bearings when assembling the hinge or small indentations in the ends of the spikes. There are no grease fittings or valves in these hinges. Sometimes the oiler or threaded hole is retained but the oiler is missing. The injected grease fills the cavity of the cross and goes to the bearings, and its excess is squeezed out through rubber gland "flow" seals.

Figure: 4 Details of the universal joint of unequal angular velocities

it should be noted that with an increase in the angle between the axes of the shafts, the efficiency of the hinge decreases sharply. In some cars, to reduce this angle, the engine is positioned with a slope of 2-3. Sometimes for the same purpose rear axle set so that the main drive shaft gets a slight tilt.

However, it is unacceptable to reduce the angle between the shafts to zero, as this can lead to a rapid failure of the hinge due to the brinelling effect of the bearing needles on the surfaces with which they are in contact.

The brinelling effect of the needles increases with a large total clearance, when the bearing needles are skewed and create high pressure on the spike spike. It is believed that the total needle clearance should be less than half the diameter of the bearing needle. Bearing needles are matched to the same tolerance dimensions. Repositioning or replacement of individual needles is not permitted.

The universal joint cross must be perfectly centered. This is achieved by precisely fixing the glasses 13 (see Fig. 4) using retaining rings or covers, which are bolted to the hinge forks. The presence of a gap between the ends of the spikes of the crosspiece and the bottoms of the cups is unacceptable, as this leads to a variable imbalance of the propeller shaft during its rotation. At the same time, overtightening of the cups can cause scuffing at the ends of the spikes and the bottoms of the cups, as well as skewing the needles.

Figure: 5 Cardan shaft with two universal joints

In some cases, axial movement, which compensates for the change in the length of the propeller shaft, is preferable to provide not with a splined connection, but directly with the design of the cardan joint - such a hinge is called universal. Figure 5 shows a propeller shaft with two universal joints, a hollow pin 4 is pressed into the shaft end hole, on which two spherical rollers 1 are mounted on needle bearings 2. Centering plugs 3 with a spherical surface are inserted into the holes of the pin 4. In the housing 5 of the hinge there are two grooves of a cylindrical section of the same radius as the radius of the roller. When rotating at an angle, pin 4 has the ability, in addition to rotation around its axis, to tilt and slide on spherical rollers along the slots. In such a hinge, axial movement is accompanied by significantly lower friction losses than in a spline connection.

Figure: 6 Cardan transmission with elastic semi-cardan joint

the elastic semi-cardan joint allows the transfer of torque from one shaft to another, located at a certain angle, due to the deformation of the elastic link connecting both shafts. The elastic link can be rubber, rubber-fabric or rubber, reinforced with a steel cable. In the latter case, the semi-cardan joint can transmit a significant torque and at a slightly larger angle than in the first two cases. The advantages of the semi-cardan joint are: reduction of dynamic loads in the transmission during sudden changes in the rotational speed; no need for maintenance during operation. Due to its elasticity, such a hinge allows a small axial movement of the propeller shaft. The elastic semi-cardan joint must be centered, otherwise the balance of the propeller shaft may be disturbed.

As an example of the use of an elastic universal joint, Fig. 6 shows the cardan transmission of a VAZ-2105 car. Here, an elastic semi-cardan joint is mounted on the front end of the intermediate propeller shaft. The resilient hex link has six holes, inside which metal inserts are vulcanized. Before installing the rubber link on the bolts of flanges 1 and 3, it was preliminarily tightened around the periphery with a metal clamp, without which the holes in the coupling would not coincide with the bolts (after assembly, the clamp is removed). In this way, the rubber link is prestressed. Rubber works better in compression than in tension, so this action reduces the tensile stress when torque is transmitted through the joint.

A rigid semi-cardan joint, which is a connection that compensates for inaccuracies in installation, is currently used extremely rarely. The reason for this is the disadvantages inherent in such a hinge: rapid wear, laborious manufacturing, noise during operation.

Cardan joints are used to connect the angled cardan rolls. The universal joint shafts have a tubular section and ends welded at the ends.

In a double cardan drive (i.e., in a gear with two cardan joints and one shaft), a tip 5 with splines is welded to one end of the tubular shaft 8 (Figure 7, a), and a tip with a fork of the second cardan joint 9 is welded to the other end The propeller shaft is connected by a tip 5 to the spline hub 4 of the fork 3. The sliding spline connection of one of the cardan joints with the shaft is necessary for axial displacement of the shaft during deformation of the axle suspension springs. The spline connection is lubricated through an oiler 2, protected from the outside by an oil seal 6 with a cover and protected from dirt by a rubber bellows 7. The extreme forks of the universal joints 1 and 9 are equipped with flanges that are bolted to the flanges at the ends of the shafts. When the cardan transmission is flanged, it is easy and convenient to disassemble.

Figure: 8 Intermediate support with elastic element

in two-axle vehicles with rear axle drive, the main application was a cardan transmission with two cardan shafts: the main and intermediate. In such a transmission, the tubular main propeller shaft 19 (Fig. 7, b) has at both ends welded lugs 18 with forks of the cardan joints. The rear cardan joint connects the shaft to the rear drive axle shaft. The front fork is connected with the fork 16 by means of a cross 17, a splined shank 13, which enters the splined sleeve 12, welded at the rear end intermediate shaft 11. The cavity of the spline bushing is filled with grease through the oiler 21. The spline bushing is sealed on the shank by an oil seal 15 with a cap screwed onto the bushing on the thread. The sliding joint is protected from contamination by a rubber bellows 20. The front end of the intermediate shaft 11 is connected to the output shaft of the gearbox by means of a cardan joint 10. The intermediate shaft is mounted on an intermediate support 14 attached to the cross member of the vehicle frame.

Intermediate supports are used to suspend the intermediate shaft of the cardan transmission. The intermediate shaft support is usually made in the form of a ball bearing 1 (Fig. 8), fixed with an inner ring on the shaft and installed in a rubber cushion 2 embedded in a bracket 4, which is attached to the cross beam 3 of the car frame. The bearing is closed on both sides by caps 5, equipped with oil seals, on the sides of which there are dirt deflectors 6. The inner cavity of the bearing is filled with grease through an oiler 7.

In three-axle vehicles with an autonomous cardan drive to the intermediate and rear axles, a rigid intermediate support is installed on the intermediate axle.

1.3. Cardan drives with constant velocity joints.

The design of universal joints of equal angular velocities is based on a single principle: the anguish of contact, through which the circumferential forces are transmitted, are located in the bisector plane of the shafts. The constant velocity joints are used, as a rule, in the drive to the driving and simultaneously steered wheels. The designs of such hinges are varied. Below are some of the most commonly used ones.

Four-ball universal joint with dividing grooves ("Weiss" type). Fig. 9. Installed on a number of domestic cars (UAZ-469, GAZ-66, ZIL-131) in the drive of controlled driving wheels. When the car is moving forward, the force is transmitted by one pair of balls; when reversing - with another pair. The grooves in knuckles 2 and 3 are cut along an arc of a circle of radius R '. Four balls 6 are located at the intersection of symmetrically located grooves 5 - in the bisector plane, which ensures the equality of the angular velocities of shafts 1 and 4. The ball 7 is centering. It is kept from displacement by a pin passing through it and entering a hole in one of the fists. The balls would be installed most accurately when they intersect the grooves at an angle of 90, but the sliding of the balls would lead to rapid wear of both balls 6 and 7 and grooves 5 and to a decrease in the efficiency of the hinge.

the intersection of circles at a small angle would not ensure the accuracy of the balls in the bisector plane and could lead to jamming of the balls. Usually, the grooves are made so that the center of the circle forming the axis of the grooves is at a distance of 0.4-0.45R from the center of the hinge. Cardan joints of this type provide an angle between the shafts of 30-32. The least laboriousness of manufacture in comparison with other synchronous universal joints, simplicity of design and low cost ensured their wide distribution. The efficiency of the hinge is quite high, since rolling friction prevails in it.

Figure: 10 Ball universal joint with indexing lever (type "Rcepp"): and - installation of the hinge in the front wheel drive; b - hinge diagram

it is worth noting some of the features of this hinge that limit the possibility of its use. The transmission of force by only two balls during theoretically point contact results in high contact stresses. Therefore, a four-ball universal joint is usually installed on vehicles with an axle load of no more than 25-30 kN. During the operation of the hinge, spacer loads arise, especially if the center of the hinge does not lie on the axis of the king pin. Special thrust washers or bearings are required to accurately position the pivot.

In a worn hinge, the balls during the transmission of increased torque, when the knuckles are somewhat deformed, can fall out, which leads to the hinge jamming and loss of control. The middle parts of the grooves are most susceptible to wear, which corresponds to a straight-line motion, and the unloaded grooves wear more than the loaded ones. This is explained by the fact that the hinge is loaded with a relatively rare engagement of the front driving axle for driving in heavy road conditions, and most of the car's mileage occurs with the front axle off, when the hinge is loaded in the opposite direction by a small but long-acting torque resisting the rotation of a part of the transmission.

A six-ball universal joint with a dividing lever (Rcepp type). Fig. 10. The main elements of this hinge are a spherical fist 4, fixed on the splines of the shaft 5, and a spherical cup 3, connected to another shaft 1. On the fist and on the inner side of the cup, six meridian grooves of a semicircular cross-section are milled. The grooves are made from one center. Six balls are located in the grooves, which are connected by a separator 6. When the shafts are tilted, the balls are set in the bisector plane using a dividing lever 2, which rotates the guide cup 7, and with it the separator. The spring 8 serves to press the indexing lever to the socket in the end of the shaft 5 when the position of the lever changes as a result of the tilt of the shafts.

The positioning accuracy of the balls in the bisector plane depends on the selection of the indexing arm arms. Figure 10, b shows the position of the hinge parts when one of the shafts is tilted at an angle . Correspondingly, the separator must turn through an angle of 0.5. Proceeding from this, such a ratio of the arms of the pitch lever is selected, at which the given angle of rotation of the separator will be ensured.

The cardan joint with indexing lever allows a maximum angle of 37 вала between the shafts. Since the force in this joint is transmitted by six balls, it provides high torque transmission at low loads. There are no thrust loads in the joint if the center of the latter coincides with the axis of the pivot. The hinge has great reliability, high efficiency, but it is technologically complex: all its parts are turned and milled in compliance with strict tolerances, ensuring the transfer of forces by all balls. For this reason, the cost of the hinge is high.

Six-ball universal joint with dividing grooves (type "Bearfield"). Fig. 11. On fist 4, the surface of which is made along a sphere of radius R1 (center O), six grooves are milled. The grooves of the knuckle have a variable depth, since they are cut along the radius R3 (the center O1 is displaced from the center of the hinge O by a distance a). The inner surface of the housing 1 is made along a sphere of radius R2 (center O), it also has six grooves of variable depth, cut along the radius R4 (center O2 is displaced relative to the center of the hinge o also by distance a). The separator 3, in which the balls 2 are located, has an outer and an inner surface made along a sphere of radii R2 and R1, respectively. In a position where the shafts of the joint are coaxial, the balls are in a plane perpendicular to the axes of the shafts passing through the center of the joint.

Figure: 11 Six-ball universal joint (Bearfield type):

and - construction; b - scheme.

when one of the shafts 5 is tilted at a certain angle, the upper ball is pushed out of the narrowing space of the grooves to the right, and the lower ball is moved by the separator into the expanding space of the grooves to the left. The centers of the balls are always at the intersection of the groove axes. This ensures their location in the bisector plane, which is a condition for synchronous rotation of the shafts. To prevent the balls from jamming, the angle at which the axes of the grooves intersect should not be less than 1120 '.

In contrast to the universal joint with a dividing lever, in this joint, the profile of the groove section is not made along an arc of a circle, but along an ellipse. Due to this, the forces of interaction between the walls of the groove and the ball make an angle of 45 with the vertical, which protects the edges of the grooves from crushing and chipping. The absence of an indexing lever allows this joint to operate at a 45 ° angle between the shafts. The relatively large losses in the hinge at a large angle between the shafts are explained by the fact that, along with rolling friction, it is also characterized by sliding friction.

Figure: 14 Three-pronged rigid universal joint (tripod type)

the joint is installed in the driveshaft of the front steered and driving wheels of some domestic cars (VAZ-2108) at the outer end of the driveshaft. In this case, a cardan joint must be installed on the inner end of the cardan shaft, which makes it possible to compensate for the change in the length of the cardan shaft when the springs are deformed.

Universal six-ball universal joint (type GKN). Fig. 12. On the inner surface of the cylindrical body of the hinge, six longitudinal grooves of elliptical section are cut, the same grooves are on the spherical surface of the knuckle parallel to the longitudinal axis of the shaft. The grooves contain a set of balls installed in the separator. The interacting surfaces of the fist and the separator are spherical, the radius of the sphere is R1 (the center O1 at a distance a from the center O lying in the plane of the centers of the balls). The spherical outer part of the cage (radius R2) becomes conical, which limits the maximum shaft tilt angle to about 20 до.

As a result of the displacement of the centers of the spheres of the cage, the balls are set and fixed in the bisector plane when the shaft is tilted. This is explained by the fact that when the shaft is tilted, the ball must move relative to two centers O1 and O2, which forces the ball to be installed at the intersection in the vertical plane passing through the center of the ball, the outer and inner spheres of the separator.

Axial movement occurs along the longitudinal grooves of the body, and the movement of the propeller shaft is equal to the working length of the body grooves, which affects the dimensions of the hinge. During axial movements, the balls do not roll, but slide, which reduces the efficiency of the hinge. This is how the internal hinge of front-wheel drive VAZ cars is made. When transmitting high torques, an eight-ball joint of this type is used.

Figure: 15 Three-pin universal universal joint ("Tripod" type)

niversal six-ball universal joint with dividing grooves ("Lebro" type). Fig.13. The hinge consists of a cylindrical body 1, on the inner surface of which six straight grooves are cut at an angle to the generatrix of the cylinder, arranged in the order shown in the figure; a spherical fist 2, six straight grooves are also cut on its surface; separator 3 with balls 4, centered by the outer spherical surface along the inner cylindrical surface of the housing 1, and by the inner spherical surface, are installed with a certain gap on the knuckle 2. The balls are installed at the intersections of the grooves, which ensures synchronous rotation of the shafts, since the balls, regardless of the angle between shafts are always in the bisector plane.

This joint is smaller than other types of joints, since the working length of the grooves and the stroke of the balls are 2 times less than the stroke of the shaft. There are other advantages: the cage does not perform the function of dividing the angle between the shafts, it is less loaded, and therefore the requirements for the accuracy of its manufacture are lower; the presence of a flange joint of the hinge provides

Figure: 16 Double cardan joint

the quality of installation, although its design becomes more complicated, which carried

how much compensates for the simplification of the body groove pulling. High demands are placed on the accuracy of the groove positioning.

The hinge has high efficiency and is used on front-wheel drive vehicles.

Three-stud cardan joint (Tripod type). Such cardan joints are installed on light-duty cars and trucks. Structurally, these hinges have two designs: hinges that allow the transfer of moment at angles between the shafts up to 43, but do not allow axial displacement (rigid hinges), and universal hinges that allow axial compensation, but operate at relatively small angles between the shafts.

In the rigid hinge (Fig. 14), the spikes 2, located at an angle of 120, are fixed in the body 1. The rollers 3 with a spherical surface are mounted on the spikes and can freely rotate on them. The fork 4, made together with the shaft 5, has three grooves of a cylindrical section. The surface of the fork is spherical, which provides a large angle between the shafts.

The principle of operation of the rigid and universal joints is the same. The universal three-stud joint (Fig. 15) consists of a cylindrical body 3, made in one piece with the shaft, in which there are three longitudinal grooves, a hub 2 with three studs, fixed on the inner end of the propeller shaft, three rollers 1 on needle bearings. The spikes, like the grooves, are located at an angle of 120 to one another. The rollers have a spherical surface of the same radius as the cylindrical section of the longitudinal grooves. When the shafts rotate at an angle, the rollers roll in the grooves, turning on needle bearings, and at the same time the pins can move along the bearing rollers, which is ensured by the hinge kinematics. Elongation is achieved by sliding the stud along the bearings.

This type of universal joint can be used if the maximum shaft tilt angle does not exceed 25. The advantage of the hinge is low losses during axial movement, since this is provided practically only by rolling, which determines the high efficiency of the hinge.

Double cardan joint. Fig. 16. It consists of two joints 1 of unequal angular velocities, united by a double fork 2. Equality of angular velocities must be ensured by the indexing lever. However, due to the design features, the synchronous rotation of the connected shafts can only be ensured with some approximation. The coefficient of uneven rotation depends on the angle between the shafts and on the size of the dividing device.

The double pivot on needle bearings is characterized by significant wear on these bearings and on the studs of the crosspieces. This is due to the fact that due to the predominantly rectilinear motion of the vehicle, the bearing needles do not roll, as a result of which the surfaces of the parts with which they come in contact are prone to brinelling, and the needles themselves sometimes flatten.

Cam cardan joint. Fig. 17. Cam joints are used on heavy-duty vehicles and drive to drive wheels. If we divide the cam gimbal into two parts along the axis of symmetry, then each part will be a gimbal of unequal angular velocities with fixed rolling axes (just like a double gimbal). Due to the presence of developed surfaces of interacting parts, the hinge is capable of transmitting a significant amount of torque while ensuring the angle between the shafts is 45-50.

On foreign heavy-duty vehicles, a cam cardan joint is widely used, shown in Fig. 17, a, known as the "Tract hinge". It consists of four stamped parts: two forks 1 and 4 and two shaped fists 2 and 3, the rubbing surfaces of which are subjected to grinding.

In our country, a cam cardan joint was developed (Fig. 17, b), which is installed on a number of vehicles (KamAZ-4310, Ural-4320, KAZ-4540, KrAZ-260, etc.). The hinge consists of five simple configuration parts: two forks 1 and 4, two knuckles 2 and 3 and a disc 5, therefore it is often called a disc. The complexity of its manufacture, in comparison with the complexity of the "Tract hinge", is somewhat large. The maximum value of the angle between the shafts provided by this joint is 45.

The efficiency of cam joints is lower than the efficiency of other joints of equal angular velocities, since sliding friction is characteristic of their elements. In operation, there is significant heating, and sometimes scuffing of the hinge parts as a result of unsatisfactory feed lubricant to the friction surface.

1.4. Materials of the main parts of the driveline

Sliding forks of cardan joints of unequal angular velocities are made of steel 30X and 40 (GAZ) or steel 45 (ZIL), and welded ones are made of steel 40 (GAZ) or 35 (ZIL), and then subjected to HFC hardening. The crosses are stamped from steel 20X (GAZ) or from steels 18ХГТ and 20ХГНТР (ZIL), The crosses made of the first two steels are cemented, the crosses from steel 20ХГНТР are subjected to nitrocarburizing. Cardan shafts are made of steel thin-walled cardan pipes (steel 15A or 20), and their slotted ends are made of steel 30, 40X or 45G2.

1.5. Choosing a prototype

In the GAZ-2410 car, the rear axle is the driving one. The cardan drive must transmit torque from the output shaft of the gearbox located at the front of the vehicle to the drive gear of the main drive of the rear axle. The reactive moment on the rear axle is perceived by the springs. Therefore, the use of a closed cardan drive is impractical. Hinges of equal angular velocities are used in drives for driven driven wheels, therefore, in this case, simple hinges of unequal angular velocities with crosspieces on needle bearings are used. The car is not long wheelbase, the distance from the output shaft of the gearbox to the main gear is small, so it is possible to use a cardan gear with one cardan shaft without an intermediate

Figure: 18. Kinematic diagram driveline prototype

weft support. The number of cardan joints is two (at the ends of the shaft). Thus, uniformity of rotation of the main gear drive gear will be ensured. It is also necessary to provide compensation for the change in the distance between the gearbox and the main gear, which occurs due to vibrations of the rear axle on the suspension when the vehicle is moving. It is convenient to make a compensating spline connection at the junction of the cardan transmission and the output shaft of the gearbox. Fastening of the cardan transmission to the driving gear of the rear axle for easy removal / installation of the transmission is flanged.

Thus, as a prototype, a double-joint cardan transmission with simple cardan joints of unequal angular speeds with crosspieces on needle bearings with one cardan shaft without an intermediate support is chosen. The compensating element is the splined joint of the cardan drive with the output shaft of the gearbox. The kinematic diagram is shown in Fig. 18.

2. Checking calculation of the cardan transmission of the GAZ-2410 car

The verification calculation of the cardan transmission is carried out in the following sequence:

the load mode is set;

the maximum torsional stress and the angle of twisting of the propeller shaft are determined;

the axial force acting on the propeller shaft is determined;

an assessment of the uneven rotation of the propeller shaft and the inertial moment arising from the uneven rotation is carried out;

the crosspiece of the universal joint is calculated;

the universal joint fork is calculated;

the permissible forces acting on the needle bearing are determined;

the critical number of revolutions of the propeller shaft is determined;

thermal calculation of the universal joint is carried out.

2.1. Load modes

The propeller shafts are affected by the torque transmitted from the gearbox and the axial forces arising from the vibrations of the drive axle on the springs. When the rotational speed increases, lateral vibrations of the propeller shaft may occur. The transverse bending of the shaft occurs due to centrifugal forces arising from the mismatch of the axis of rotation of the shaft with its center of gravity. Mismatch can occur due to inevitable manufacturing inaccuracies, shaft deflection under its own weight, and other reasons.

In this work, the verification calculation of the cardan transmission is carried out according to the maximum torque developed by the engine - Mmax at a rotational speed nM - when the car is moving in first gear, when the torque transmitted through the transmission is maximum ( gear ratio first gear i1 \u003d 3.5). The rated maximum torque developed by the engine (173 Nm at 2500 rpm) in the design assignment is increased by 1.5 times, thus, the calculated torque will be Mmax \u003d 173  1.5 \u003d 259.5 Nm; nM \u003d 2500 rpm.

2.2. Determination of the torsional stress and the angle of rotation of the propeller shaft

The maximum torsional stress of the shaft, as noted earlier, is determined for the case when the maximum motor torque is applied and under the action of dynamic loads. The action of dynamic loads is taken into account by the dynamic factor: KD \u003d 1 ... 3. In the calculation, we take KD \u003d 1.

The cardan shaft of the GAZ-2410 car is hollow. The outer diameter of the shaft is D \u003d 74 mm, the inner diameter of the shaft is d \u003d 71 mm.

The moment of resistance to torsion is determined by the formula

The maximum torsional stress of the shaft is determined by the formula

The torsional stresses in the made designs of the cardan gears have values \u200b\u200bof 100 ... 300 MPa. The resulting voltage value does not exceed the specified values.

The value of the angle of twisting of the shaft is determined by the formula

where G is the torsional modulus of elasticity, G \u003d 8.51010 Pa;

Icr - moment of inertia of the shaft section during torsion,

l is the length of the propeller shaft, l \u003d 1.299 m.

The value of the twist angle of the cardan shaft unit length is

.

The values \u200b\u200bof the torsion angles in the made designs of cardan shafts are at KD \u003d 1 from 3 to 9 degrees per meter of shaft length. The resulting value does not exceed the specified values.

Thus, the normal operation of the universal joint shaft in terms of maximum torsional stresses and twisting angle is ensured.

2.3. Determination of the axial force acting on the propeller shaft

In addition to the torque, axial forces Q act on the propeller shaft, arising from the movements of the drive axle.

The rear axle, when the vehicle is moving over bumps, swings relative to the spring shackle axis along a certain radius R1. The cardan shaft oscillates around the center of the cardan joint, which connects it to the gearbox output shaft along a certain radius R2. Due to the inequality of these radii, axial movements of the propeller shaft occur. The value of axial displacements in the prevailing modes of operation is 2-5 mm.

The magnitude of the axial force Q acting on the propeller shaft during vehicle vibrations is determined by the formula

,

where Dsh and dsh are the diameters of the splines along the protrusions and depressions;

 - coefficient of friction in the spline connection.

Figure: 19 Cardan drive diagram for evaluating uneven rotation of shafts

the coefficient  depends on the quality of the lubricant. With good lubrication  \u003d 0.04 ... 0.6 (in the calculation we take 0.05); with poor lubrication  \u003d 0.11 ... 0.12 (in the calculation we take 0.115). In case of jamming  \u003d 0.4 ... 0.45 (in the calculation we take 0.45). For the splined joint of the cardan drive of the GAZ-2410 car Dsh \u003d 28 mm, dsh \u003d 25 mm.

Then the values \u200b\u200bof the axial force will be:

with good lubrication

;

with poor lubrication

;

when jammed

.

Axial forces occurring in the cardan drive load the bearings of the gearbox and final drive. A reduction in axial load will occur when there is a joint in which sliding friction during axial movement is replaced by rolling friction (splines with balls).

2.4. Estimation of non-uniformity of rotation and inertial moment

For a single cardan joint connecting the output shaft of the gearbox (shaft A) and the cardan shaft (shaft B), the ratio between the angles  and  of rotation of the shafts (see Fig. 19) can be represented by the expression

.

Here 1 is the angle between the axes of the shafts under consideration (skew angle). Differentiating this expression, we obtain

The angular speeds of the shafts are derived from the angle of rotation over time. With this in mind, from the previous expression, you can get the ratio between the angular speeds of the shafts:

.

After algebraic transformations, we obtain the dependence of the angular speed of the driven shaft B on the angular speed of the drive shaft A, the angle of rotation of the drive shaft and the angle of misalignment of the shafts:

.

This dependence implies that A \u003d B only when 1 \u003d 0. In the general case, 1  0, that is, at a uniform speed of rotation of shaft A, shaft B will rotate unevenly. The amount of difference between the values \u200b\u200bзначенияA and B depends on the angle between the shafts 1. By setting the angle of rotation of the shaft A, it is possible to estimate the uneven rotation of the shaft B at a constant angle between the shafts and at a constant rotation speed of the drive shaft.

As noted above, the driveline is calculated for the maximum torque case. The engine develops maximum torque at nM \u003d 2500 rpm. The maximum torque is transmitted through the transmission when the first gear is engaged. Under these conditions, the speed of rotation of the drive shaft A is determined by the formula

.

We take the maximum angle of misalignment of the shafts - --1 \u003d 3.

Fig. 20 Graphs of dependence of angular velocities cardan shafts from the angle of rotation of the drive shaft

the values \u200b\u200bof the angular speed of the shaft B, depending on the angle of rotation of the shaft A, are presented in Table 1. The graph of the dependence is in Figure 20.

Table 1.

The value of the angular speed of the universal joint shafts at different angles of rotation of the drive shaft.

grad.

The ratio between the angles of rotation of the shafts B and C has the form

.

Let us prove that if the misalignments of the shafts are equal, i.e. when 1 \u003d 2, the angular velocities of the shafts A and C will also be equal. Taking into account the position of the forks of shaft B and the displacement of the leading forks of the hinges by 90 relative to each other, we obtain, counting the angle of rotation from the position of shaft A,

Or

.

Considering that

, from the obtained expression, we find the ratio between the angles of rotation of shaft A and shaft C:

.

From this dependence it is seen that for 1 \u003d 2,

, and hence  \u003d . Thus, the uniformity of rotation of the main gear drive gear is ensured with uniform rotation of the secondary shaft of the gearbox, although the propeller shaft itself, through which the torque is transmitted, rotates unevenly.

When the car is moving, due to uneven rotation, the shaft B will be additionally loaded with an inertial moment

,

where IA and IB are the moments of inertia of the rotating parts, reduced respectively to the shafts A and B.

2

Figure: 21 Design diagram of the universal joint crosspiece

.five. Calculation of the universal joint cross

Force P acts on the spike of the universal joint cross (Fig. 21). The magnitude of this force is determined by the formula

,

where R is the distance from the axis of the cross to the middle of the thorn, R \u003d 33 mm.

Force P acts on the spike spike, causing it to crush, bend and shear. The collapse stress of the spike should not exceed 80 MPa, the bending stress - 350 MPa, the shear stress - 170 MPa.

The shear stress is determined by the formula

where d is the diameter of the spike, d \u003d 16 mm;

l is the length of the thorn, l \u003d 13 mm.

The moment of resistance to bending of the cross-section of the spike is determined by the formula

Bending stress

Cutoff voltage

As you can see, all voltages do not exceed the permissible values.

The forces P applied to the pins also give the resultant N, which causes tensile stresses in the n-n section. For the GAZ-2410 universal joint cross, the cross-sectional area in which these stresses arise is F \u003d 4.9 cm2. Tensile stresses are determined by the formula

Allowable tensile stress is 120 MPa. The actual voltage does not exceed the permissible one. Normal operation of the pins of the universal joint cross for crushing, bending, shearing and the cross of the joint in tension is ensured.

2

Figure: 22 Scheme for calculating the universal joint fork.

.6. Calculation of the universal joint fork

When checking the calculation of the universal joint fork, a weak section of the fork leg is selected. The diagram for calculating the universal joint fork is shown in Figure 22. The paw perceives the force P from the spike of the crosspiece. Under the action of this force, bending and torsion stresses arise simultaneously in the section of the paw, which is made close to rectangular.

The length and width of the section, determined from the drawing, are respectively equal to a \u003d 45 mm, b \u003d 15 mm. The shoulders of the action of the forces are equal to c \u003d 21 mm, m \u003d 3 mm. Coefficient  required when determining the moments of resistance of a section depends on the ratio of the length and width of the section. For a given section (a / b \u003d 3)  \u003d 0.268.

To determine the stresses acting in the considered section of the paw of the universal joint fork, it is required to determine the moments of resistance of the sections.

The moment of resistance of the section to bending about the x-x axis (see Fig. 22)

Moment of resistance to bending about the y-y axis

The moment of resistance to torsion when determining the stresses at points 1 and 3

The moment of resistance to torsion when determining the stresses at points 2 and 4

Bending stress at points 2 and 4

Bending stress at points 1 and 3

Torsional stress at points 2 and 4

Torsional stress at points 1 and 3

The largest resulting stresses at the considered points of the section are determined according to the theory of the energy of deformation of the resistance of materials (4th theory of strength). According to this theory, the greatest resulting stress from bending and torsion at points 1 and 3

The highest resulting stress at points 2 and 4

The values \u200b\u200bof permissible stresses in the completed structures are [] \u003d 50 ... 150 MPa. As you can see, at points 1 and 3, the actual stresses are outside the permissible limits. To provide normal work cardan joint forks, it is necessary to reduce the stresses acting in its cross-sections. This can be achieved by increasing the dimensions of the section, increasing, for example, its width b. From the formula for the maximum resulting stress from bending and torsion at points 1 and 3, you can obtain the following formula for the selection of the section width:

.

Let us take the stress that needs to be provided at points 1 and 3 of the section, [] \u003d 140 MPa. Then the b value is 16.9 mm. That is, to ensure the normal operation of the universal joint fork, the width of the section of its paw must be increased by 2 mm.

2.7. Determination of the allowable force acting on the needle bearing

The allowable effort is determined by the formula

,

where i is the number of rollers or needles, i \u003d 29;

l - the working length of the roller, l \u003d 1.4 cm;

d - roller diameter, d \u003d 0.2 cm;

k is a correction factor for hardness. With the hardness of the rolling surfaces of the spike of the crosspieces of the bearing housing and the rollers themselves, which are 59-60 according to Rockwell, k \u003d 1.

The number of revolutions of the stud per minute is determined by the formula (for the angle between the axes of the propeller shafts  \u003d 3)

.

Then the allowable effort will be equal to

In paragraph 2.5. the real force acting on the spike was determined. It is transmitted to the universal joint yoke and loads the needle bearing. Its value (P \u003d 13.8 kN) does not exceed a certain permissible value of the force loading the needle bearing. Therefore, normal bearing operation is assured.

2.8. Calculation of the critical number of revolutions of the propeller shaft

When the shaft rotates due to centrifugal forces arising from even a slight mismatch between the axis of rotation of the shaft and the center of gravity, lateral shaft loss may occur. When the rotation speed approaches the critical one, the amplitude of the lateral vibrations of the shaft increases and the shaft may break. Therefore, the cardan shaft is balanced during manufacture.

The value of the critical angular velocity кр is influenced by:

the nature of the pinching of the shaft in the supports;

the size of the clearances in the joints and bearings;

misalignment of parts;

out-of-roundness and wall thickness of the pipe and a number of other factors.

For a shaft of constant cross-section with a uniformly distributed load equal to its own weight and freely lying on supports that do not perceive bending moments

,

where l is the length of the shaft between the supports, l \u003d 1.299 m;

E - modulus of elasticity, E \u003d 21011 N / m2;

I - moment of inertia of the shaft section;

m is the mass of a unit of shaft length.

Considering that

So what

(D, d are the outer and inner diameters of the hollow section of the shaft, equal to 75 mm and 71 mm, respectively), we obtain the following formula for determining the critical angular velocity

.

Then the critical speed of the propeller shaft will be determined

For normal operation of the propeller shaft, it is necessary that the following condition ncr  (1.15 ... 1.2) nmax be met. Here nmax is the maximum rotational speed of the propeller shaft. It is equal to the maximum engine speed, which for the GAZ-2410 is about 5000 rpm. Thus, ncr should not be less than 5750 ... 6000 rpm. As you can see, this condition is met and the normal operation of the cardan transmission is ensured.

2.9. Thermal calculation of the universal joint

The work of friction on the pins of the universal joint causes it to heat up. The heat balance equation can be represented in the following form:

where L is the power supplied to the cardan joint, J / s;

dt is the operating time of the cardan joint, s;

m is the mass of the part, kg;

c - specific heat capacity of the part material (for steel c \u003d 500 J / (kgC));

k is the heat transfer coefficient, in this calculation it is assumed k \u003d 42 J / (m2sС);

F '' - cooling surface of heated parts, m2;

 - the difference between the temperature of the heated parts of the universal joint T1 and the temperature of the ambient air T2, С;

d - increase in temperature of heated parts of the universal joint, С.

It can be seen from the heat balance equation that one part of the heat supplied to the cardan joint due to the friction work is spent on heating the cardan joint parts. Another part of it is transferred to the environment. The purpose of the thermal calculation is to determine the heating of the cardan joint parts depending on the operating time. This heating is determined by the value  \u003d T1 - T2. Before the hinge starts to work, the temperature of its parts is taken to be equal to the ambient temperature. Knowing the amount of heating and the temperature of the surrounding air, you can determine the real temperature of the hinge parts.

Before drawing up the heat balance equation, it is necessary to find the area of \u200b\u200bthe cooling surface of the cardan joint parts. Schemes for determining this area are shown in Figure 23.

Cooling surface areas are defined as areas of simple flat geometric shapes. They make up:

outer cheek area Sout. n. \u003d 0.00198 m2;

the area of \u200b\u200bthe inner cheek Sint. n. \u003d 0.00156 m2;

lateral cheek area S-side. n. \u003d 0.0006 m2;

the area of \u200b\u200bhalf of the surface of the cross is Scross. \u003d 0.0009 m2.

Figure: 23 Heat transfer surfaces of heated parts of the universal joint:

and) -outer cheek of the fork; b)- inner cheek of the fork; in)- side cheek of the fork; d)- crosspiece.

when determining the total area of \u200b\u200bthe cooling surface of the cardan joint parts, it is necessary to take into account that the surface of the inner cheek of the fork is not completely used for heat transfer, since it includes the spike of the crosspiece on the needle bearing. The bearing radius is R \u003d 15 mm. Then the total area will be determined

Also, to draw up the heat balance equation, a mass of parts is needed, to which part of the heat generated by friction in the hinge is transferred. The weight of the cross, determined from its working drawing, is mcross. \u003d 0.278 kg. The mass of the fork cheek can be determined by the formula ( \u003d 7800 kg / m3 - the density of the material of the parts)

The total mass of parts m will then be mcross. + 4m cheeks \u003d 1.018 kg.

The power L supplied to the universal joint is determined by the formula

,

where Mmax is the maximum torque developed by the engine, Mmax \u003d 259.5 Nm;

i1 - gear ratio of the first gear of the gearbox, i1 \u003d 3.5;

 - coefficient of friction between the cleat and the fork,  \u003d 0.03;

dsh - diameter of the spike of the cross, dsh \u003d 0.016 m;

n is the rotational speed of the universal joint at the maximum power developed by the engine, determined by the following formula:

;

R is the distance from the axis of rotation of the plug to the point of application of the force, R \u003d 0.036 m;

 is the angle of inclination between the shafts,  \u003d 3.

Thus, the power supplied to the universal joint will be equal to

The heating of the universal joint is determined by the formula

.

The value of parameter A is

.

After substituting all known numerical values \u200b\u200binto the formula for determining the heating of the universal joint, we obtain the following relationship between the heating and the operating time of the universal joint:

.

The dependence of the heating of the parts of the universal joint on the time of its operation is presented in Table 2. The graph of dependence is in Figure 23.

Table 2.

Values \u200b\u200bof heating of parts of the universal joint, depending on the time of its operation.

Gimbal running time

Figure: 23 Dependence of the difference between the temperature of the heated parts of the universal joint and the temperature of the ambient air on the operating time of the universal joint.

It can be seen from the graph that after the start of the hinge operation, the heating of the parts gradually increases and after some time is established approximately constant and equal to 45.8С. This indicates the balancing of the processes of heat generation and its removal into the material of parts and the environment. GAZ-2410 cardan joint needle bearings are lubricated with TAD-17i or TAP-15V gear oils. The upper limit of the temperature range of their application is approximately 130 ... 135С. If we take the ambient temperature equal to 25С, then the temperature of the parts of the universal joint, after 4 hours of its operation, will be approximately 70С. It can be seen that it does not exceed the upper limit of the grease application range. Therefore, normal lubrication conditions and normal operation of the universal joint are ensured.

Conclusion

In paragraph 2 of the course project, a verification calculation of the cardan transmission of the GAZ-2410 car was performed. The purpose of this calculation was to test the performance of the cardan transmission with an increase in the transmitted torque by 1.5 times compared to the nominal one given in the technical characteristics of the car.

The calculation showed that under new operating conditions:

shear torsional stresses arising in the cross section of the propeller shaft do not exceed the permissible values;

the angle of twisting of a unit of shaft length is within acceptable limits;

crushing, shearing and bending stresses of the gimbal cross studs and the stretching stress of the universal joint are permissible;

the real force acting on the needle bearing does not exceed the calculated maximum possible,

the ratio between the critical rotational speed of the propeller shaft and its maximum operating rotational speed required for the normal operation of the propeller shaft is met;

when the cardan joint operates, the normal temperature of the parts is ensured.

Unsatisfactory results were obtained only when calculating the universal joint fork - the maximum stresses at individual points of the section went beyond the permissible limits. (see clause 2.6). To ensure normal fork operation, it is necessary to increase the cross-sectional area of \u200b\u200bits paws. The dimensions of the enlarged section are given in section 2.6.

Thus, the operability of the cardan transmission of the GAZ-2410 with an increase in the transmitted torque by 1.5 times is ensured with practically no changes in the transmission design (with the exception of an increase in the cross-section of the paw of the universal joint). This suggests that when designing the car, the cardan gear (and therefore the entire transmission) was designed "with a margin". When choosing the initial data for the calculation, it was assumed that the ZMZ-4021 engine was installed on the un-modernized car, developing a torque of 173 Nm. However, as indicated in the operating manual, the ZMZ-402 engine, which develops a torque of 182 Nm, can be installed instead. When installing various power units, changes in the vehicle's transmission are not provided. According to the results of the calculation performed in this work, it can be seen that on the GAZ-2410 car it is possible, without significant changes in the design of the cardan transmission, to install an engine that develops a torque of about 260 Nm.

Literature

Volga automobiles: Operation manual. - 7th ed. - Gorky: Printing house of the automobile plant, 1990 .-- 176 p. - (Department of design and experimental work of the Gorky Automobile Plant).

Anokhin V.I. Domestic cars. - M .: Mechanical Engineering, 1968 .-- 832 p.

Bashkardin A.G., Kravchenko P.A. Cars. Workflows and Calculation Basics. - L .: LISI, 1981 .-- 58 p.

Zvyagin A.A., Kravchenko P.A. Car design. Course "Cars", part 3. Issue 1: vehicle transmission. - L .: LISI, 1975 .-- 88 p.

A short automobile reference book. - 10th ed., Rev. and add. - M .: Transport, 1985. - 220 p., Ill., Tab. - (State scientific research Institute of automobile transport).

Osepchugov V.V., Frumkin A.K. Automobile: Structural analysis, calculation elements: A textbook for university students specializing in Automobiles and Automotive Industry. - M .: Mechanical Engineering, 1989. - 304 p., Ill.

GAS - Thesis \u003e\u003e Transport

Power transmission, it includes: clutch, box gear, gimbal broadcast, home broadcast, differential ... on power transmission... In power transmission car GAS-51A is installed ... and in balance calculations the average actual ...

Approved and put into effect

By order Rostekhregulirovanie

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

AUTOMOTIVE VEHICLES

DRIVE TRANSMISSION VEHICLES WITH JOINT

UNEQUAL ANGULAR SPEEDS

GENERAL TECHNICAL CONDITIONS

Vehicles. Cardan gears of vehicles with joints

of unequal angle speeds. General technical requirements

GOST R 52430-2005

Group D25

OKS 43.040.50;

OKP 45 9128

Date of introduction

Foreword

Objectives and principles of standardization in Russian Federation established by the Federal Law of December 27, 2002 N 184-FZ "On technical regulation", and the rules for the application of national standards of the Russian Federation - GOST R 1.0-2004 "Standardization in the Russian Federation. Basic provisions".

Information about the standard

1. Developed by the Federal State Unitary Enterprise "Central Order of the Red Banner of Labor Research Automobile and automotive institute"(FSUE" NAMI "), JSC" BELKARD ".

2. Introduced by the Technical Committee for Standardization TC 56 "Road Transport".

3. Approved and put into effect by the Order of the Federal Agency for Technical Regulation and Metrology of December 28, 2005 N 407-st.

4. Introduced for the first time.

1 area of \u200b\u200buse

This standard applies to driveshafts with hinges of unequal angular speeds, their assemblies and parts intended for transmissions of motor vehicles (hereinafter referred to as ATC) of categories M and N according to GOST R 52051. It is allowed to apply the standard to driveshafts of other vehicles, machines and mechanisms.

This standard uses references to the following standards:

GOST R 52051-2003. Mechanical vehicles and trailers. Classification and definitions

GOST 8.051-81. State system for ensuring uniformity of measurements. Errors allowed when measuring linear dimensions up to 500 mm

GOST 9.014-78. Unified system of protection against corrosion and aging. Temporary anti-corrosion protection of products. General requirements

GOST 9.104-79. Unified system of protection against corrosion and aging. Paint and varnish coatings. Operating conditions groups

GOST 15.309-98. System of product development and launching into production. Testing and acceptance of manufactured products. Basic provisions

GOST 15140-78. Paints and varnishes. Methods for determining adhesion

GOST 15150-69. Machines, devices and other technical products. Versions for different climatic regions. Categories, operating conditions, storage and transportation in terms of the impact of climatic factors of the external environment.

Note. When using this standard, it is advisable to check the operation of the reference standards in the public information system - on the official website of the national body of the Russian Federation for standardization on the Internet or according to the annually published information index "National Standards", which is published as of January 1 of the current year, and the corresponding monthly information signs published in the current year. If the referenced document is replaced (changed), then when using this standard, one should be guided by the replaced (modified) document. If the referenced document is canceled without replacement, then the provision in which the link to it is given applies to the extent that does not affect this link.

3. Terms and definitions

The following terms are used in this standard with the corresponding definitions:

3.1. Cardan drive: ATS unit, consisting of two or more cardan shafts, intermediate supports (if necessary) and designed to transmit torque from one unit to another, the axes of the shafts of which do not coincide and can change their relative position.

3.2. Cardan shaft: a shaft made in the form of a pipe or a rod or in a combination of a pipe and a rod, with cardan or semi-cardan joints, including elastic semi-cardan joints, which can have a mechanism for changing the length of the shaft.

3.3. Cardan joint: a kinematic rotary pair designed to connect shafts with intersecting axes and provide the ability to transmit torque at a variable angle.

3.4. Double cardan joint: a kinematic unit consisting of two cardan joints of unequal angular velocities, connected by connecting surfaces or by means of a common part.

3.5. Propeller shaft length: distance between the connecting surfaces of the joint flanges.

Notes. 1. It is allowed to take the distance between the centers of the hinges or other structural elements as the length of the shaft, for example, the distance from the center of the hinge to the center of the bearing of the intermediate support.

2. If there is a mechanism for changing the length of the propeller shaft, its minimum length should be taken as the distance between the connecting surfaces of the flanges in the fully compressed position of the propeller shaft, and for the maximum length - the total value of the minimum length of the propeller shaft and the maximum allowable travel in its length changing mechanism.

3.6. Mechanism for changing the length of the propeller shaft: a device that provides a change in the length of the propeller shaft when the distance between the units connected by the propeller shaft changes.

3.7. Cardan shaft length: distance between the connecting surfaces of the cardan shaft (cardan shafts) or other structural elements.

3.8. Propeller shaft intermediate support: A mechanism used to support the connection of two propeller shaft shafts.

3.9. Angles of installation of the cardan transmission: the angles in the joints of the cardan transmission of a vehicle with a total mass on a horizontal surface.

3.10. Maximum angle pivot angle: the maximum possible pivot angle during a pivot movement.

3.11. Pivot moment: the moment required to overcome the resistance to relative angular movement in the pivot.

3.12. Effort of axial movement in the mechanism for changing the length of the propeller shaft: the force required for the relative axial movement of the elements of the mechanism, not loaded with the torque and (or) bending moments of the propeller shaft.

3.13. Angle of rotation of the forks of the propeller shaft: relative angular displacement of the axes of the holes of the propeller shaft forks.

4. Main parameters and technical requirements

4.1. The main parameters of cardan gears are:

Minimum length;

Maximum length;

Maximum angle of rotation in the hinge;

Effort of axial movement in the mechanism for changing the length;

Imbalance;

Torque that can be sustained without permanent deformation;

Torque withstand without breaking parts.

4.2. The calculation of the critical speed of the propeller shaft is given in Appendix A.

4.3. The permissible imbalance of the propeller shaft, referred to each of the supports, should not exceed the product of its mass attributable to these supports, and the specific unbalance indicated in Table 1.

Table 1

The norms of the specific unbalance of the propeller shaft

┌───────────────────────────────────┬─────────────────────────────────────┐

│Maximum speed Specific imbalance referred to│

│ of the cardan shaft in the transmission, кар to the support of the cardan shaft, g x cm / kg, │

│-1│ not more than│

├───────────────────────────────────┼─────────────────────────────────────┤

│Up to 500 incl. 25│

│Sv.500 "1500" │15│

│"1500"2500"│10│

│"2500"4000"│6│

└───────────────────────────────────┴─────────────────────────────────────┘

Notes. 1. For short shafts that do not have a pipe or with a pipe up to 300 mm, the permissible imbalance is set in the design documentation (CD) of the developer.

2. The calculation of the unbalance of the propeller shaft falling on its supports is given in Appendix B. According to the results of the calculation (if necessary), the design should be optimized to reduce the gaps in the hinges, the mechanism for changing the length or reducing the mass of the propeller shaft or propeller shaft.

4.4. The maximum torque transmitted by the cardan drive or cardan shaft must not exceed the values \u200b\u200bspecified in the design document, corresponding to:

Absence of residual deformations of the cardan transmission or cardan shaft;

No damage to the cardan drive or cardan shaft.

4.5. The permissible values \u200b\u200bof the radial runout of the propeller shaft tube, radial and axial clearances in the hinges, the forces of axial movement in the mechanism for changing the length, the moment of rotation in the hinge are set in the design documentation of the developer enterprise.

4.6. Assembled cardan drives should be painted in accordance with the requirements of GOST 9.104.

Allowed non-staining cages of bearings, cavities of flanges, crosses, inner surfaces of ears and plugs of forks.

The connecting and centering surfaces of cardan transmission flanges should be protected from painting in accordance with the requirements of the manufacturer's design documentation.

4.7. The adhesion of the film of the propeller shaft paintwork should not exceed 2 points in accordance with GOST 15140.

4.8. The applied paints and varnishes must allow the possibility of tinting the driveshafts with air-drying paints.

4.9. Purchased products with a limited shelf life should be used to assemble driveshafts within the time specified in the documents for the supply of these products.

4.10. The installed driveline resource must not be less appropriate the PBX resource for which it is intended.

4.11. Permissible angles of installation of cardan shafts in transmissions are given in Appendix B.

4.12. Permissible deviations in the shape of the connecting surfaces of the forks-flanges of propeller shafts, flanges of units connected by propeller drives are given in Appendix D.

5. Acceptance rules

5.1. Acceptance control (PC) of products is carried out by the technical control service (STC) of the manufacturer.

5.2. Cardan drives and their elements are subject to acceptance tests (PSI) and periodic tests (PI) after acceptance control. The tests are carried out in accordance with GOST 15.309 and the technical documentation of the manufacturer.

5.3. If the supply contracts provide for acceptance by an independent body (representative of the customer or consumer), then acceptance is carried out by the specified representative office in the presence of the manufacturer's STK.

5.4. Periodic tests of cardan transmissions are carried out on at least three products, at least once every six months. Positive test results basic models cardan transmissions are allowed to be extended to their design options (modifications, variants).

Periodic tests of driveline modifications may be replaced by tests of the base model.

5.5. Parameters verified during tests (PSI, PI) are given in Appendix D.

5.6. The consumer has the right to conduct a random check of the compliance of cardan transmissions, their units and parts with the requirements of this standard and the design documentation of the developer.

Verification is carried out within the scope of the STK acceptance control

6. Methods of control (testing)

6.1. Completeness, correct assembly, appearance of welded seams, external condition protective coating, the absence of cracks, dents and other mechanical damage on the surface of pipes and associated parts, the fastening of the balancing plates (see Appendix E) is checked visually.

6.2. Linear and angular dimensions are measured with maximum permissible errors established by GOST 8.051.

6.3. The angles of rotation in cardan joints, as well as the angle of rotation of the forks of the cardan shaft, are measured by means of angular measurements with an error of +/- 1 °.

6.4. The radial runout of the propeller shaft tube is measured when basing along the connecting surfaces with an error of +/- 0.01 mm.

6.5. The radial and axial clearances in the hinge or their total value are measured with an accuracy of at least 0.01 mm. Clearance values \u200b\u200bare allowed to be determined based on the results of measurements of the dimensions of the crosspiece and bearings taking into account possible axial displacements (along the spikes of the crosspiece) in the "bearing-fork" joints.

6.6. The force of axial movement in the length-changing mechanism is determined with an accuracy of 5% of the maximum value.

6.7. The pivot moment is determined with an accuracy of 2.5% of the maximum value.

6.8. To assess the strength of cardan shafts and cardan joints, they are affected by the torque specified in the design document, with an accuracy of 2.5% of its value.

6.9. The imbalance of the propeller shaft is determined with an accuracy of 10% of the permissible value, with an unbalance of less than 20 g x cm - with an accuracy of 2 g x cm.

6.10. Drive shafts must be dynamically balanced. The dynamic balancing mode is established in the design documentation by the enterprise-developer of the cardan transmission, provided that the imbalance norms given in Table 1 are ensured.

6.11. Cardan drives must be balanced as an assembly with all shafts and intermediate bearings.

The possibility of separate balancing of cardan shafts with more than three cardan joints is set in the design documentation of the developer enterprise.

6.12. The balancing of cardan shafts with a mechanism for changing the length should be carried out at the length specified in the design documentation of the manufacturer.

6.13. Fork flanges of cardan gears weighing more than 5 kg should be additionally balanced before assembling the cardan gear according to the design documentation of the developer.

6.14. When re-installing on the balancing machine, the imbalance of the propeller shaft must not exceed the permissible value.

6.15. The imbalance check is carried out after checking the scale division value. measuring instrument in accordance with 6.9 and the correct setting of the balancing machine.

6.16. The adhesion of the film of the cardan transmission paintwork should be determined by the method of lattice notches in accordance with GOST 15140.

6.17. The hardness of the surface layer of the spikes of the crosses is checked in accordance with the manufacturer's procedure.

7. Marking

7.1. Cardan drives are marked to ensure their identification. The content of the marking, the method and place of application on the product are set in the design documentation of the developer enterprise in accordance with.

8. Packaging

8.1. Packing of cardan drives, assemblies and parts must ensure their safety from mechanical damage, the impact of precipitation and pollution. The type of packaging, as well as the possibility of its absence, is indicated in the delivery documents.

9. Transportation and storage

9.1. Cardan drives, units and parts are transported by any type of transport, ensuring their safety from mechanical damage, pollution and precipitation. Group of transportation conditions 6 (ОЖ2), storage - 3 (Ж3) in accordance with GOST 15150.

It is allowed by agreement between the manufacturer and the consumer to apply other conditions of transportation and storage in accordance with GOST 15150.

9.2. All unpainted outer metal surfaces of cardan drives, their assemblies and parts for assembly or spare parts should be preserved in accordance with GOST 9.014 for the period specified in the delivery documents.

10. Instructions for use

10.1. Operation and maintenance of cardan transmissions should be carried out in accordance with the operation manual of the vehicle on which they are installed.

11. Manufacturer's Warranties

11.1. The manufacturer guarantees the compliance of cardan transmissions with the requirements of this standard, subject to the rules of operation, transportation and storage established by the company.

11.2. Warranty period operation and warranty operating time of cardan drives supplied for the complete set should not be less guaranteed term and warranty operating time of the automatic telephone exchange for which they are intended.

11.3. The warranty period and the warranty operating time of cardan drives supplied for the complete set are calculated in accordance with the warranty obligations for the vehicle, and for those supplied as spare parts - from the moment they are installed on the vehicle.

Cardan gears supplied for the complete set should be installed on the PBX within the time specified in the technical documentation for the product.

11.4. The guaranteed storage period for cardan drives is no more than 12 months.

The guaranteed shelf life of cardan drives is calculated from the date of shipment of the product.

application AND

(reference)

CALCULATION OF THE CRITICAL SPEED OF THE PROPELLER SHAFT

For a propeller shaft with a steel pipe, the critical speed,, is calculated by the formula

, (1)

where D is the outer diameter of the pipe, cm;

d is the inner diameter of the pipe, cm;

L - the maximum distance between the axes of the driveshaft hinges, cm;

where is the frequency of rotation of the propeller shaft in the transmission (natural frequency of transverse vibration of the shaft in the first form), corresponding to maximum speed ATC,.

Notes. 1. In this calculation, the elasticity of the supports is not taken into account.

2. For cardan gears with an intermediate support, the L value is taken equal to the distance from the pivot axis to the intermediate support bearing axis.

The critical frequency of rotation of the shaft, made in the form of a rod between the cardan joints, is calculated with d equal to zero.

The critical frequency of rotation of the propeller shaft, consisting of a pipe and a rod, is calculated based on the reduced value of the pipe length, cm, according to the formula

, (2)

where is the length of the shaft pipe, cm;

The length of the tube replacing the shaft rod, see.

The length of the pipe replacing the shaft rod is calculated by the formula

, (3)

where is the length of the shaft rod, cm;

Shaft rod diameter, cm.

The critical frequency of rotation of the propeller shaft, taking into account the elasticity of its supports in the transmission, is established experimentally by the vehicle developer enterprise.

The frequency of rotation of the propeller shaft in the transmission, corresponding to the maximum possible speed of the vehicle, should be no more than 80% of the critical frequency, taking into account the elasticity of the supports.

application B

(reference)

CALCULATION OF PROPELLER SHAFT IMBALANCE

1. The imbalance of the propeller shaft depends on its mass and clearances in the joints and the mechanism for changing the length.

2. Unbalance D, g x cm, in the cross section of the cardan drive support is calculated by the formulas:

For a shaft without a length-changing mechanism; (1)

For a shaft with a mechanism for changing the length, (2)

where m is the mass of the propeller shaft per support, g;

The total displacement of the shaft axis, caused by the axial clearances in the hinge between the ends of the cross and the bottoms of the bearings and the radial clearance in the connection "cross pivot - cross bearing", cm;

Shaft axis displacement due to clearances in the length change mechanism, see.

The mass m is determined by weighing on a balance placed under each support of a horizontally located shaft.

The total displacement of the shaft axis, cm, is calculated by the formula

, (3)

where H is the axial clearance in the hinge between the ends of the cross and the bottoms of the bearings, cm;

Inner diameter in the bearing on the needles, cm;

Cross pin diameter, cm.

The shaft axis displacement, cm, is determined taking into account the design of the length change mechanism. For example, for a movable spline connection with centering on the outer or inner diameter is determined by the formula

, (4)

where is the diameter of the spline hole in the bushing, cm;

Spline shaft diameter, cm.

Note. For a universal joint shaft without a length change mechanism \u003d 0.

The minimum and maximum unbalance D is calculated taking into account the tolerance field of the mating elements of the cardan transmission or cardan shaft.

The actual imbalance of the propeller shaft, determined by the accuracy of manufacturing the seating and connecting surfaces of the balancing equipment, as well as the seating surfaces of the transmission units, is greater than the calculated value.

application IN

PERMISSIBLE PROPELLER SHAFT MOUNTING ANGLES

The angles of installation of the propeller shaft in the transmission in the static state of the vehicle of the total mass should be no more than:

3 ° - for passenger vehicles;

5 ° - for trucks and buses;

8 ° - for all-wheel drive vehicles.

The minimum angles of installation of the universal joint shaft with joints on needle bearings must be at least 0.5 °.

For cardan shafts installed between the bogie axles, an installation angle of zero is allowed.

Appendix D

PERMISSIBLE SHAPE DEVIATIONS

FLANGE CONNECTING SURFACES

Table D.1

Shape tolerances connecting

flange surfaces

┌─────────────────────────┬──────────────┬─────────────┬──────────────────┐

│Maximum frequency│Tolerance│Tolerance Radial tolerance│

│ rotation of the cardan shaft flatness, end │ beating of the landing

│-1│ mm, no more than │ beating, mm, │ belt, mm, │

│ in transmission, min ││ no more no more

├─────────────────────────┼──────────────┼─────────────┼──────────────────┤

│ Up to 500 incl. │0.08│0.08│0.08│

│Sv.500 "3500" │0.05 │0.05 0.05│

│"3500 "5000"│0,04│0,04│0,04│

│"5000│0,03│0,03│0,03│

└─────────────────────────┴──────────────┴─────────────┴──────────────────┘

Table D.2

Permissible deviations in the shape of the connecting surfaces

flanges with end teeth

Flatness tolerance, mm, no more	End runout tolerance, mm, no more
	0,12

Note. Check of permissible deviations is carried out on rollers with a diameter of 3.5 mm.

application D

(required)

PARAMETERS CHECKED DURING TESTS

Table E.1

Parameter name and quality indicator	Acceptance control	Reception- delivery trials	Periodic trials
Cardan drive or cardan shaft
Completeness
Assembly correctness
Appearance welds
The external state of the protective coating
Absence of pipes and mating parts cracks, dents and other mechanical damage
Attaching the balancing plates
Torque threaded connections
Angles in cardan joints
Swivel torque
The presence of grease in each spike, in bearings and splines
Axial displacement force in the mechanism length changes
Residual unbalance value
Minimum length
Maximum length
Forks pivot angle
Radial pipe runout
Radial and axial joint clearances or their total value
Torsional strength
Crosspiece with needle bearings
Torsional strength