Ministry of Education and Science of the Russian Federation
FGBOU VPO Volgograd State Technical University
Faculty of road transport
Department of "Automobile Transport"
Semester work
under the discipline "Certification of vehicles"
On the topic: "Ensuring a safe level of steering"
Performed: Art. c. AT - 500.
Javadov A.A.
Checked: Shustov A.V.
Volgograd 2013.
Introduction ........................................................................ ... ............ 3
1. Purpose of the steering ................................................... ..5
2. The design of the steering ................................................... 7
3. Home Types of steering mechanisms and drives ................................. 9
3.1.Read mechanism .....................................................................9
3.2.Read drive ..................................................................... 10
4. Prospects and disadvantages of the steering of the steering .................. ..12
4.1 Steering Hydrausselter (GUR) .............................. ... 12
4.2 Electo-set .............................................................................. 14
4.3 Advantages and disadvantages ...................................................... 15
5. High-safe steering mechanism ..............................................17
6. Technical Requirements for Steering according to GOST R 41.12-2001..18
Conclusion ................................................................................................22
List of sources used ................................................ ... 23
Introduction
The need for people in the need for accelerated movement on the ground led humanity to the creation different machines And the mechanisms, the most convenient and favorite of which became the car.
The word "car" means the "self-dividing wagon", although in a modern sense of cars, it is customary to call only the means of movement equipped with autonomous engines (internal combustion, electric, steam).
An interesting history of development was the steering mechanism of the car. Now, no one will not surprise it by the location - for the right-hand movement - on the left, for the left-sided - right. But this layout of the steering wheel was determined not immediately. Strict division of the carriageway on the left and right side of the movement occurred only in the 20th century, and on the streets with not too lively movement continued to ride as it would have to. Up until the 60s of the 20th century, it was not preferred by movement on a specific side of the street. England, her former colonies, Japan still adhere to the left, Sweden rebuilt from left to right only in 1967, Austria, Hungary and Czechoslovakia - in the 1930s. Milan went on the left side, and on the rest of Italy - on the right. With such a variety of rules, it could not be a single look at the root. When instead of the lever appeared steering columnThat was to be directly in front of the driver, the designers showed the unanimity - the steering wheel is installed only on the right. That is why the steering wheel, almost all the first cars, was on the right. Of particular interest is the management methods of the first centuries of the twentieth century. Workplace The driver contained such a large number of all sorts of handles and control levers, which was not wise to get confused in them. Some of the brake levers were three - on the transmission shaft, on the rear wheels and on the so-called "mountain focus" - a pointed rod, which lowered onto the road when moving on the rise, since the brakes on the slope of the car did not hold (the prototype of a modern "parking brake" ). Is it possible to reach the lever, whether it is convenient to use - the designer was not interested. The lever was installed where the design required. Thus, the driver was committed to acrobatic movements. But it lasted not long. There were more cars, the possibility of choice appeared, and not all drivers have already agreed on such "acrobatics." It would be logical to focus levers and handles in one place, closer to the drivers of the driver. Such a place was elected steering column. When she was tilted (for the first time on the car "Latil" in 1898), then the management of transmissions from the column no longer succeeded. At the same time, it was found that the accumulation of levers and handles near the steering wheel creates confusion. Part of them were replaced by pedals.
At the beginning of the twentieth century, the car required from the driver of a good physical form. Natural output was an increase in the steering control of the gear ratio, but it did not give a solution to the problem. In 1925, American Francis Davis patented a special device called "Hydraulic Steering Amplifier". True, the design of instant success did not gain. However, the principle and the path of improvement outlined: from the late 30s - early 40s in America, and then in Europe, designers begin to put the GUR on some of their cars. Today this device is equipped with the whole cargo vehicles And a considerable share of passenger.
1. Purpose of the steering
The change in the direction of the vehicle is carried out by turning relative to its longitudinal axis of controlled wheels, which, as a rule, are the front wheels.
Due to the rotation of the driven wheels, the velocity vector of each of them, the parallel longitudinal axis of the car ceases to match the plane of rotation of the wheels. As a result, side forces perpendicular to the wheels planes occur in contact of the wheels with expensive. These lateral forces force controlled wheels and the car as a whole to deviate from straight movement and turn.
The steering provides the necessary direction of movement of the car by separate and coordinated rotation of its controlled wheels. The combination of mechanisms that serve to rotate controlled wheels are called steering control.
Steering is used to change the direction of the car. With a fixed front axis, the change in the direction of movement of the car is carried out by turning the front controlled wheels.
The steering consists of a steering wheel connected to the shaft with the steering mechanism and the steering drive. Sometimes an amplifier is turned on in the steering.
The steering mechanism is called a slowing transmission, transforming the rotation of the steering wheel shaft into rotation of the tower shaft. This mechanism increases the driver's effort applied to the steering wheel and makes it easier to work.
The steering drive is called the system of thrust and levers, which combines a car with a steering mechanism.
In order for the car while moving the car, it makes a turn without lateral slip of the wheels, they all have to roll on arcs of different lengths described from the center of the turn "O" (Fig. 1). In this case, front controlled wheels must be rotated on different angles. Internal rotation of the wheel should be rotated at the angle of alpha-c, the outer - to the smaller angle of alfa-n. This is provided with a compound of tag and steering levers in the form of a trapezoid. The base of the trapezium is the beam front Bridge The car, the sides are the left and right swivel levers, and the peak of the trapezium forms a transverse thrust that connects with the levers of articulated. Rotary trumps of wheels are rigidly attached to the levers.
Figure 1- Car turning circuit
where: 1-bull of the front bridge of the car; 2 and 4-rotary levers; 3-cross traction; 5-rotary wheel pinings; 6-long trigger.
2. Steering Design
The location and interaction of the parts of the steering, which does not have an amplifier can be considered in the diagram (Fig. 2.A). Here, the steering mechanism consists of a steering wheel, a steering shaft and a steering wheel transmission formed by the engagement of the worm gear (worm) with a gear stopper, which is attached to the shaft of the steering wheel. Cup and all other steering parts: longitudinal thrust, upper lever of the left swivel pin, lower levers of the left and right pivoting pin, transverse thrust make up the steering wheel drive.
The rotation of the controlled wheels occurs when the steering wheel is rotated, which transmits the rotation of the steering transmission through the shaft. In this case, the worm of the transmission that is in engaging with the sector begins to move the sector up or down by its cutting. The sector shaft comes into rotation and deflects the tower that is attached to the protruding part of the sector shaft with its top end. The deviation of the tower is transmitted by the longitudinal thrust, which moves along its axis. The longitudinal thrust is connected through the top lever with a swivel pin, so its movement causes a turn of the left swivel pin. From it, the force of rotation through the lower levers and transverse craving is transmitted to the right pin. Thus, there is a turn of both wheels.
The controlled wheels are rotated by the steering control on a limited angle equal to 28-35 °. The restriction is entered in order to exclude when turning the hooks of parts of the suspension or body of the car.
The steering design is very much dependent on the type of suspension of controlled wheels. With the dependent front wheels suspension, in principle, the steering circuit shown on (Fig. 2. (A)), independent suspension (Fig. 2. (b)) The steering wheel is somewhat complicated.
Figure 2 steering steering:
a) with the dependent front wheels suspension
where: 1-steering transfer; 2-steering shaft; 3-steering wheel; 4- turning trumps; 5th 7-rotary levers; 6-cross traction; 8-longitudinal traction; 9-coshka;
b) with independent suspension
where: 1-tower; 2-swivel levers of the RACF; 3 and 6-side traction; 4-major transverse traction; 5-pendulum lever.
This type of steering mechanism is set on separate passenger carsmobile representative classas well as heavy trucks carsmobile and buses.
The screw steering mechanism of the car includes the following main elements: screw, installed on the steering wheel shaft; nut moving along the screw; Shooty rail, sliced \u200b\u200bon a nut; toothed sector connected to the rail; steering tushLocated on the shaft of the sector, i.e., two working pairs are involved in the work of the mechanism - screw nut and rail-toothed sector.
The screw and nut applied in the screw steering mechanism differ from the usual screw pair by the fact that specially performed cavities between the side surfaces of the pair are filled with balls.
Rolling tracks for balls serve screw grooves made on the screw body and in the nut. When turning the screw, the balls are circulated in the nicketer on a closed circle, rolling out of the screw channel through the hole on one side of the nut and returning to the nut through the rope canal from the opposite side.
The use of circulating balls allows you to replace the friction of sliding in a pair of screw-nut friction rolling, which increases the efficiency of transmission, as in by direct directionand in the opposite. This improves the conditions for stabilizing controlled wheels, but also makes the mechanism quite sensitive to the shocks from the road. Therefore, shock absorbers or steering amplifiers should be installed for smoothing shocks.
The screw groove depth is performed by the variable, and the thickness of the middle tooth of the sector enlarged compared to other teeth to eliminate the swap mechanism in extreme positions.
The principal operation of the screw steering mechanism differs little from the work of the worm mechanism. The rotation of the steering wheel is accompanied by the rotation of the screw, which moves the nut mating with it. At the same time, the circulation of balls, significantly reduced friction between the screw surfaces.
Nut through a toothed rail moves the toothed sector and with it the steering tower.
The gap in the engagement of the piston-rail with the sector of the tip shaft is adjustable by axial movement of the tower shaft using a special adjusting screw.
The clearance in a pair of screw-nut is not regulated, so high reliability and the required service life in this gearing are provided by applying high-quality alloyed steels.
The helical steering mechanism in comparison with the worm mechanism has a larger efficiency and is able to transmit great efforts.
One of the disadvantages of this design is the complexity of fitting the components of the screw transmission when used in the circulating balls.
Rule mechanism ZIL-431410
The device of the screw steering mechanism of the car ZIL-431410 is shown in Fig. 3.
The gearbox connects with the steering wheel shaft using cardanian Vala With two hinges. Carter 3
gearbox cast from cast iron and has a lower 1
Intermediate 9
, top 14
and sideways 19
Covers.
In the crankcase placed piston-rail 4
in which the ball nut is installed fixed 6
. Ball nut is collected with a screw in such a way that screw grooves are formed in which the balls are invested 8
.
In the groove of the ball nut, connected by two holes with its screw groove, insert two stamped gutters. 7
forming a tube on which balls, rolling out when turning the screw 5
From one end of the nut, returned to its other end.
Piston Reika 4
is in engaging with the toothed sector 18
Vala 21
Cup, which rotates on the bronze sleeves pressed into the crankcase. The axial movement of the tower shaft is made by rotating the adjusting screw 20
whose head is included in the hole of the Tshaka shaft.
When wrapped adjusting Bolt. decreases the gap in the engagement of the rail-toothed sector, increasing due to this moment of resistance to turning should not exceed 500 N.. On the outer shlusted end of the shaft is set 23
.
When the steering wheel is rotated, the driver's effort is transmitted through the steering wheel shaft and cardan transmission on screw 5
. Ball nut 6
moves along the screw axis, carries the rack piston 4
which produces a turn of the toothed sector 18
With a shaft 21
Cupie around their axis.
Effort from Cushkin 23
Transmitted to the steering wheel drive, which rotates the wheelchair.
According to the same scheme, the steering mechanisms of cars of MAROK "KAMAZ", "KRAZ", "MAZ", "BELAZ".
In the previous article called "", we figured out what the mechanism of the steering in the car is needed and why such requirements are prescribed to it. And now let's look at the species of steering controls actively installed on modern cars.
For a long time, automotive designers and did not think about the servus of the steering wheel. Low requirements for manageability and comfort and a small contact spot relatively narrow tires allowed to do with one human force even in controlling heavy trucks. The means to reduce the effort on the steering wheel was one thing: make a more gear ratio of the drive and the label diameter. And with the fact that the driver will have to adopt a huge steering wheel of five or six revolutions from the removal to the abundance, and the accuracy of the control will be low, it was necessary to put up.
First, the steering amplifiers appeared on heavy machinery - career dump trucks. It happened in the late 1930s, before the war. True, first began to use pneumotors - they were uncomplicated and sweated from the compressor or intake manifold . But the hydraulics, although it was more difficult and more expensive than pneumatics, worked quieter and more accurately. On it and stopped constructors of passenger cars. In 1951, Chrysler Crown Imperial serial cars began to equip Hydraguide hydraulic amplifiers for the first time as standard equipment. And in Europe in 1954, Citroen DS 19 was acquired by the hydraulic agent.
Steering gear.
The steering mechanism is used to increase and transmit to the steering wheel of the effort attached by the driver to the steering wheel. In passenger cars, the steering mechanisms of worm and rack type are used. The advantages of the worm-roller mechanism include: a low tendency to transfer shocks from road irregularities, large corners of the wheel turning, the ability to transfer great effort. The disadvantages are a large number of thrust and hinged joints with ever-accumulating backlash, "heavy" and a non-informative steering wheel. The minuses in the end turned out to be weighty advantages. On the modern cars Such devices are practically not used.
The most common to date is the Rack Steering Mechanism. Small mass, compactness, low price, minimum number of thrust and hinges - All this has led to wide use. The mechanism of the "Rake gear" is ideal for the front-wheel drive layout and, ensuring greater lightness and accuracy of the steering. However, there are also disadvantages: due to the simplicity of the design, any push from the wheels is transmitted to the steering wheel. Yes, and for heavy machines, such a mechanism is not quite suitable.
Steering wheel drive.
The steering wheel drive is designed to transmit effort from the steering mechanism to controlled wheels, while ensuring their rotation to unequal angles. If both wheels are turned to the same value, the inner wheel will turn on the road (sliding sideline) that will reduce the steering efficiency. This is a sliding, which also creates additional heating and wheel wear, can be eliminated by turning the inner wheel to a larger angle than the angle of rotation of the external wheel. When moving on a turn, each of the wheels describes its circle different from the other, and the external (far from the center of rotation) moves to a larger radius than the internal one. And since they have a common turning center, then, accordingly, the inner wheel must be rotated for a larger angle than the external one. This is ensured by the design of the so-called "steering trapezium", which includes rotary levers and steering thrust with hinges. The required ratio of the angles of rotation of the wheels is ensured by the selection of the angle of inclination of the steering levers relative to the longitudinal axis of the car and the length of the steering levers and the transverse thrust.
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- Steering gear worm-type
consists of:
- steering wheel with shaft,
- Carter Worm Couple,
- Couple "Worm Creek",
- Steering tower.
In the steering mechanism crankcase in constant engagement there is a pair of "worm-roller". The worm has nothing but the lower end of the steering shaft, but the roller, in turn, is on the shaft of the steering bump. When rotating the steering wheel, the roller begins to move along the helical cutting worm, which leads to the rotation of the shaft of the steering bump. Wormari, like any other toothed connection, requires lubricant, and therefore oil is poured into the steering mechanism, the mark of which is indicated in the instructions for the car. The result of the interaction of the "Worm-Roller" pair is the transformation of the rotation of the steering wheel in the rotation of the steering bump in the one or the other side. And then the force is transmitted to the steering wheel drive and already on the controlled (front) wheels. In modern cars, a safe steering shaft is used, which can be folded or breaking when the driver is hit steering wheel During the accident to avoid serious damage to the chest.
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Steering wheel drive applied with worm-type mechanism includes:
- right and left side traction,
- middle traction
- pendulum lever,
- Right and left swivel wheels.
Each tie Rod At its ends there has hinges in order for moving parts of the steering wheel to be freely rotated relative to each other and body in different planes.
- Steering mechanism "Gear - Rake".
This steering mechanism The effort to the wheels transfers with the help of the gear, installed in the bearings, and the gear rail, moving in the guide bushings. To ensure the unconnected rail, the rail is pressed against the gear springs. The steering gear is connected by the shaft with the steering wheel, and the rake is with two transverse traction, which can be attached in the middle or at the ends of the rail. These mechanisms are small gear ratioWhat makes it possible to quickly rotate controlled wheels to the desired position. A complete rotation of controlled wheels from one extreme position to another is carried out for 1.75 ... 2.5 steering wheel turns.
One of the main systems that ensure the safety of movement by car is steering. Purpose of the car's steering is the ability to change the direction of movement, make turns and maneuvers when rounding obstacles or overtaking. This component is also important as brake system. Proof of this is the prescription of traffic rules, the operation of the car with the faulty specified mechanisms is strictly prohibited.
Features of the node and design
On cars, a kinematic method of changing the direction of movement is used, which implies that the rotation occurs due to the change of the position of the controlled wheels. Usually manageable is the front axle, although there are cars with a so-called infringement system. The peculiarity of the work in such cars is that the wheels of the rear axle are also rotated when the direction is changed, albeit for a lower angle. But while this system has not received widespread.
In addition to the kinematic method, the technique is also used by force. The peculiarity of him is that to complete the rotation of the wheel of one side, they slow down, while on the other side they continue to move at the same speed. And at least this way of changing the direction on the passenger car distribution did not receive, it is still used on them, but in a few other quality - as a system of course stability.
This assembly of the car consists of three main elements:
- steering column;
- steering gear;
- drive (system of thrust and levers);
Steering knot
Each component has its own task.
Steering column
Performs the transmission of rotational effort that creates a driver to change the direction. It consists of a steering wheel located in the cabin (the driver rotating it). It is rigidly planted on the column shaft. In the device of this part of the steering, the shaft is very often used, divided into several parts interconnected by cardan hinges.
This design is not just so. First, it allows you to change the angle of the steering wheel on the mechanism, to shift it in a certain direction, which is often necessary when laying component parts Auto. In addition, this design allows you to increase the comfort of the cabin - the driver can change the position of the steering wheel on the departure and the slope, providing the most convenient position.
Secondly, the composite steering column has the property "Broke" in case of accident, reducing the likelihood of injury to the driver. The essence is as - with frontal blow, the engine can shift back and push the steering mechanism. If the column shaft was solid, the change in the position of the mechanism would lead to the outlet of the shaft with the steering wheel in the cabin. In the case of a composite column, the movement of the mechanism will be accompanied by only a change in the angle of one component of the shaft relative to the second, and the column itself remains fixed.
Steering gear
It is designed to transform the rotation of the shaft of the steering column to the translational movements of the drive elements.
Summer-toothed rack mechanisms are the greatest distribution on passenger cars. Previously, another type was used - the "worm-roller", which is now mainly used on trucks. Another option for trucks is "screw".
"Rake gear"
Distribution type "Rake gear" received thanks to relatively simple device steering mechanism. This constructive node is made of three main elements - the housing in which the gear is located and perpendicular to it - the rail. Between the two last elements there is a constant gearing.
This type of mechanism works like this: the gear is rigidly connected to the steering column, so it rotates with the shaft. Due to the toothed connection, the rotation is transmitted to the rail, which is shifted inside the case in one direction or another. If the driver rotates the steering wheel to the left, the interaction of the gear with the rail leads to the fact that the latter moves to the right.
Often, the mechanisms "gear-rail" with a fixed gear ratio are used on the car, that is, the rotation range of the steering wheel to change the wheel angle of the same with all their positions. For example, suppose that for rotation of the wheels to the angle of 15 ° it is necessary to do 1 full turn steering wheel. So, it doesn't matter, in what position there are controlled wheels (extreme, straightforward), for turning to the specified angle will have to make 1 turn.
But some automakers are installed on their auto mechanisms with a changing gear ratio. Moreover, it is achieved quite simply - by changing the angle of the position of the teeth on the rail in certain zones. The effect of this refinement of the mechanism is: if the wheels are straight, then 1 turnover is required to change their position on the same 15 ° (example). But if they are in the extreme position, then due to the modified gear ratio, the wheels turn to the specified angle through the half turn. As a result, the rotation range of the steering wheel "from the edge to the edge" is significantly less than in the mechanism with a fixed gear ratio.
Rake with variable gear ratio
In addition to the simplicity of the device, the type "gear-rail" is used even because in such a design it is possible to implement the actuators of the hydraulic fracture (GUR) and the electric powerful (EUR), as well as the electrohydraulic (EGUR).
"Worm-roller"
The next type is a "worm-roller", less common and on passenger cars is practically not practically used, although it can be found on the VAZ of the classical family.
The basis of this mechanism is the worm transmission. Represents a worm screw with a thread of a special profile. This screw is located on the shaft connected to the steering column.
With the thread of this worm contacts the roller connected to the shaft, to which the tower is planted - the lever interacting with the drive elements.
Worm steering mechanism
The essence of the operation of the mechanism is: when the shaft is rotated, the screw rotates, which leads to the longitudinal movement of the roller along its thread. And since the roller is installed on the shaft, then this displacement is accompanied by turning the latter around its axis. This in turn leads to the semicircular movement of the bump, which affects the drive.
From the mechanism of the "worm-roller" type on passenger cars, they refused to use the "gear-rail" due to the inability to integrate the hydraulicel in it (on the cargo car, he still had, but the executive mechanism was rendered), as well as a sufficiently complex design of the drive.
Screw type
The design of the screw mechanism is even more complicated. It also has a screw with threads, but it does not contact with a roller, but with a special nut, on outside which is applied to the toothed sector, interacting with the same, but made on the shaft of the bump. There are also mechanisms with intermediate rollers between the nut and the gear sector. The principle of action of such a mechanism is practically identical to worm - as a result of the interaction, the shaft turns and pulls the tower, and that in turn - the drive.
Screw steering mechanism
On the screw mechanism, the hydraulicel can be installed (the nut serves as a piston), but it does not apply on the passenger car due to the massiveness of the structure, therefore it is used only on trucks.
Drive unit
The drive in the steering design is used to transmit the rejection or tower to transmit control wheels. Moreover, the problem of this component includes changing the position of the wheels at different angles. It is determined by the fact that the wheels are moving along different radius when turning. Therefore, the wheel S. inner When changing the trajectory of movement should be rotated for a larger angle than the external one.
The design of the drive depends on the mechanism used. So, if the "Gear Rake" is used on the car, the drive consists of only two thrust connected to the swivel fist (the role of which performs a shock absorption rack) by means of a ball tip.
To the rail, these thrust can be attached in two ways. Less common is the rigid fixation by their bolted compound (in some cases, the connection is carried out through the silent block). For such a connection in the mechanism body, a longitudinal window has been done.
A more common method of connecting a rigid, but moving connection with the ends of the rail. To ensure such a compound at the end of both traction, a ball tip is made. Through the nut, this ball is pressed against the rail. When the last thrust moves, changes its position, which provides an existing connection.
In drives, where the worm-roller mechanism is used, the design is much more complicated and represents a whole system of levers and thrust that has received the setting of the steering trapezium. So, for example, on the VAZ-2101, the drive consists of two sideways, one medium, pendulum lever and swivel fists with levers. At the same time, to ensure the possibility of changing the corner of the wheel position rounded fist Cold to pendant levers with two ball supports (top and bottom).
A large number of compound elements, as well as compounds between them, makes such a type of actuator more susceptible to wear and the occurrence of hopes. This fact is another reason for the failure of the worm mechanism in favor of robust.
"Feedback"
It is worth noting that in the steering mechanism there is also the so-called " feedback" The driver not only affects the wheels, and through it also receives information about the peculiarities of the movement of the wheels on the road. It is manifested in the form of vibrations, jerks, creating definitely aimed effort on the steering wheel. This information is considered very important to properly assess the behavior of the car. Proof of this is the fact that in cars equipped with GUR and EUR, designers have saved "feedback".
Advanced development
This node continues to improve, so the latest achievements are systems:
- Active (dynamic) steering. It allows you to change the gear ratio of the mechanism depending on the vehicle speed. Also performs I. additional feature - adjustment of the angle of the front wheels in turns and when braking on a slippery road.
- Adaptive steering (wire control). This is the newest and promising system. It does not have a direct connection between the steering wheel and wheels, everything works at the expense of sensors and actuators (servo drives). The system has not yet received a lot of distribution due to psychological and economic factors.
System "Handles on Wires"
Conclusion
In general, the mechanism is a fairly reliable node that does not require any maintenance. But at the same time, the operation of the car's steering implies a timely diagnosis to identify faults.
The design of this node consists of a plurality of elements with moving connections. And where there are such compounds, with time due to the wear of the contacting elements, they appear in them, which can significantly affect the controllability of the car.
The complexity of the steering diagnosis depends on its constructive execution. So in the nodes with the mechanism of the "gear-rail" of the compounds that need not so much: tips, gear gear with a rail, steering column cardan.
But with a worm mechanism due to the complex design of the diagnostic point drive significantly more.
Concerning repair work in case of violation of the workability of the node, then the tips are strong wear Just replaced. In the steering mechanism, at the initial stage, the backlash can be removed by adjustment of the engagement, and if it does not help, the bulkhead of the node using Remkomplekt. Cardana columns, as well as tips - are simply replaced.
AUTOLEEK.There are several types of steering mechanism. You know that when the steering wheel is rotated, the wheels of the car are rotated. But certain actions occur between the rotation of the steering wheel and turn the wheels.
In this article, we will look at the features of the two most common types of steering mechanism: the robes steering mechanism and the steering mechanism with a ball nut. We also tell me about the steering with the hydraulic agent and learn about interesting technologies for the development of steering systems, allowing to reduce fuel consumption. But, first of all, we will look at how the turn is happening. Not everything is as simple as it may seem.
Turning a car
You may be surprised to find out that when you turn the wheel on the front axle through various trajectories. To ensure smooth turn, each wheel must describe the different circumference. Due to the fact that the inner wheel describes the wheel of a smaller radius, it makes a coolest rotation than the external one. If you carry out perpendicular to each wheel, the lines will intersect at the central point of rotation. The geometry of rotation causes the inner wheel to rotate stronger than the external one.
There are several types of steering mechanism. The most common is the wheels steering mechanism and a steering mechanism with a ball nut.
Rack steering mechanism
The robes steering mechanism is widely used in passenger cars, low load trucks and SUVs. In fact, this mechanism is quite simple. Rush gears are located in a metal tube, on each side of which the rail is. The steering tip is connected to each side of the rail. The drive gear is conjugate with the steering shaft. When you turn the steering wheel, the gear begins to rotate and leads the rail in motion. The steering tip on the end of the rail is connected to the steering tower on the spindle (see Figure).
The functions of the gear rack with gears are as follows:
- It converts the rotational movement of the steering wheel in straight trafficrequired for rotation of the wheels.
- It provides a gear ratio to facilitate the rotation of the wheels.
The transfer ratio of the steering mechanism is the relation of the degree rotation of the steering wheel to the degree of rotation of the wheels. For example, if one complete turnover of the steering wheel (360 degrees) rotates the wheel by 20 degrees, then the transfer ratio of the steering mechanism is 18: 1 (360 divided by 20). The higher the attitude, the more degree rotation of the steering wheel. At the same time, the higher the attitude, the less effort to be attached.
As a rule, in the lungs sports cars The transfer ratio of the steering mechanism is lower than that large cars and trucks. With a low gear ratio at the steering mechanism, a faster response, so you do not need to turn the steering wheel with an effort to rotate. Than less carThe smaller its mass, and even with low gear ratio, does not require an additional force for turning.
There are also cars with a variable gear ratio of the steering mechanism. In this case, the toothed rack has a different step of the teeth (the number of teeth) in the center and on the sides. As a result, the car reacts to the rotation of the steering wheel faster (the rake is closer to the center), and the effort is also reduced when the steering wheel is rotated.
Rack steering mechanism with amplifier
In the presence of a rush steering mechanism with an amplifier, the rail has a slightly different design.
Part of the rail includes a cylinder with a piston in the middle. The piston is connected to the rail. On both sides of the piston there are two holes. Fluid supply under high pressure One of the sides of the piston leads a piston in motion, he turns the rail, ensuring the increase in the steering mechanism. Steering mechanism with ball nut
The steering mechanism with ball nut can be found on many trucks and SUVs. This system is slightly different from the rush mechanism.The steering mechanism with ball nut includes worm gear. Conditionally worm gear can be divided into two parts. The first part is a metal block with a threaded hole. This block has a teeth from the outside, which are conjugated with the gear, which leads to the steering tower (see Figure). The steering wheel is connected to a threaded rod, similar to a bolt installed in the threaded hole of the block. When the steering wheel rotates, the bolt turns with it. Instead of screwing into a block, like ordinary bolts, this bolt is fixed in such a way that when it rotates, it leads to a motion block, which, in turn, leads to worm gear. 
The bolt does not come into contact with the carving with the block, since it is filled with ball bearings circulating the mechanism. Ball bearings are used for two purposes: they reduce the friction and wear of the transfer, and also reduce the contamination of the mechanism. If there are no balls in the steering mechanism, for some time the teeth will not touch each other and you will feel that the steering wheel has lost the rigidity.
The hydraulicer in the steering mechanism with the ball nut functions in the same way as in the rush steering mechanism. The amplification is ensured by the supply of fluid under high pressure on one side of the block.
Power steering
In addition to the steering mechanism itself, the hydraulicer includes several main components. Pump
The plate pump supplies the steering mechanism by hydraulic energy (see Figure). The engine leads a pump with a belt and pulley. The pump includes driving blades rotating in the oval shape chamber.When rotating the blade, the hydraulic fluid of low pressure from the return highway into high pressure exhaust hole is pushed. The stream strength depends on the number of revolutions of the car engine. The pump design provides the necessary pressure even on idling. As a result, the pump moves a greater amount of fluid when the engine is running to more high revolutions.
The pump has a safety valve that provides proper pressure, which is especially important at high engine speeds when a large volume of liquid is supplied.
Swivel valve
The hydraulic caller should help the driver only when the power is applied to the steering wheel (when turning). In the absence of effort (for example, when moving in a straight line), the system should not provide assistance. A device that determines the application of force to the steering wheel is called a rotary valve.The main component of the rotary valve is torsion. Torque is a thin metal rod that rotates under the action of torque. The upper end of the torsion is connected to the steering wheel, and the lower with gear or worm transmission (which turns the wheels), while the torus torch torus is equal to the torque attached by the driver to rotate the wheels. The higher the attached torque, the greater Torcion turn. The input of the steering shaft shafts the inner part of the rotary valve. It is also connected to the top of the torsion. The bottom of the torsion is connected to the outer part of the rotary valve. Torock also rotates the steering gear, connecting with the drive gear or worm transmission, depending on the type of steering mechanism.
When turning, the torsion rotates the inner part of the turning valve, the external part remains fixed. Due to the fact that the inner part of the valve is also connected to the steering shaft (and, consequently, with a steering wheel), the number of revolutions of the inside of the valve depends on the torque attached by the driver.
When the steering wheel is fixed, both hydraulic tubes provide an equal value of the pressure on the gear. But when the valve is rotated, the channels are opened to supply fluid under high pressure to the corresponding tube.
Practice showed not the highest efficiency of this type of steering amplifier.
Innovative steering amplifiers
Due to the fact that the steering mechanism pump with a hydraulicer on most cars continuously pumps the liquid, it consumes power and fuel. It is logical to count on a number of innovations that will enhance fuel savings. One of the most successful ideas is a computer control system. This system completely eliminates the mechanical connection between the steering wheel and the steering mechanism, replacing it electronic system Control.In fact, the steering wheel works just like the steering wheel for computer games. The steering wheel will be equipped with sensors for supplying signals to the direction of movement of wheels and motors that ensure the response to the actions of the car. The output of such sensors will be used to control the steering mechanism with an electric drive. In this case, the need to prevent the steering shaft is eliminated, which increases the free space in the engine compartment.
General Motors introduced a HY-WIRE concept car, which already installed such a system. A distinctive feature Such System S. electronically control from GM is that you can customize the car handling with the new computer software without replacing mechanical components. In cars with electronic control of the future, you can adjust the control system for yourself by pressing only a few buttons. Everything is very simple! Over the past fifty years, the steering system has not changed much. But next decade, the era of more economical cars will come
