COOLING SYSTEM

The cooling system is designed to maintain normal engine thermal conditions.

When the engine is running, the temperature in its cylinders rises above 2000 degrees, and the average is 800 - 900 о С! If you do not remove heat from the "body" of the engine, then in a few tens of seconds after starting, it will no longer be cold, but hopelessly hot. Next time you can run your cold engine only after its overhaul.

The cooling system is needed to remove heat from the mechanisms and engine parts, but this is only half of its purpose, although more than half. To ensure a normal working process, it is also important to accelerate the warm-up of a cold engine. And this is the second part of the cooling system.

Typically applies fluid system cooling, closed type, with forced circulation of liquid and an expansion tank (fig. 25).

Figure: 25 Engine cooling system diagram
a) small circle of circulation
a) a large circle of circulation

1 - radiator; 2 - branch pipe for circulation of coolant; 3 - expansion tank;
4 - thermostat; 5 - water pump; 6 - cooling jacket cylinder block;
7 - cooling jacket of the block head; 8 - heater radiator with electric fan; 9 - heater radiator tap;
10 - plug for draining the coolant from the block; 11 - plug for draining the coolant from the radiator;
12 - fan

The cooling system consists of:

• cooling jacket of the block and cylinder head,
• centrifugal pump,
• thermostat,
• radiator with expansion tank,
• fan,
• connecting pipes and hoses.

In figure 25 you can easily distinguish between the two circles of coolant circulation. A small circle of circulation (red arrows) serves to warm up a cold engine as soon as possible. And when the blue ones join the red arrows, then the already heated liquid begins to circulate in a large circle, cooling in the radiator. Leads this process automatic device - thermostat.

To monitor the operation of the system, there is a coolant temperature indicator on the instrument panel. The normal temperature of the coolant when the engine is running should be in the range of 80-90 ° C (see Fig. 63).

I run the risk of receiving condemning words in my address, but let's imagine that a running engine is still a living organism. The temperature of any living organism is a constant value, and any change in it leads to unpleasant consequences. The same thing happens with the engine, it will not be able to work normally if its thermal regime is not correct.

Engine cooling jacket consists of many channels in the block and the cylinder head through which coolant circulates.

Centrifugal pump forces fluid to move through the engine cooling jacket and the entire system. The pump is driven by a belt drive from a pulley crankshaft engine. The belt tension is adjusted by the deflection of the generator housing (see Fig.59a) or tension roller drive camshaft engine (see Fig.11b).

Thermostat designed to maintain a constant optimal thermal condition of the engine. When starting a cold engine, the thermostat is closed, and all the liquid circulates only in a small circle (Fig. 25) for its quickest warming up. When the temperature in the cooling system rises above 80 - 85 ° C, the thermostat automatically opens and part of the liquid enters the radiator for cooling. At high temperatures, the thermostat opens completely and already all the hot liquid is directed along a large circle for its active cooling.

Radiator serves to cool the fluid passing through it due to the air flow that is created when the car is moving or with the help of a fan. The heatsink contains many tubes and "membranes" that form a large cooling surface area.

Well, everyone knows a common example of a car radiator. Each house has central or local heating radiators (batteries). They also have a special configuration, and the larger the total area of \u200b\u200bthe complex surface of the radiator, the warmer it is in your house. And at this time, the water in the heating system is actively cooled, that is, it gives off heat.

Expansion tank it is necessary to compensate for changes in the volume and pressure of the coolant when it is heated and cooled.

Fan designed to forcibly increase the flow of air passing through the radiator of a moving car, as well as to create an air flow when the car is stationary with the engine running.

Two types of fans are used: permanently on, with a belt drive from the crankshaft pulley and an electric fan that turns on automatically when the coolant temperature reaches approximately 100 degrees.

The pipes and hoses are used to connect the engine cooling jacket to the thermostat, pump, radiator and expansion tank.

The interior heater is also included in the engine cooling system. The hot coolant flows through the heater radiator and heats the air that is supplied to the vehicle interior. The air temperature in the passenger compartment is regulated by a special tap, with which the driver adds or decreases the flow of fluid passing through the heater radiator.

The main malfunctions of the cooling system.

Leakage of coolant may appear due to damage to the radiator, hoses, gaskets and oil seals.

To eliminate the malfunction, it is necessary to tighten the hose and pipe clamps, and replace the damaged parts with new ones. In case of damage to the radiator pipes, you can try to "patch" holes and cracks, but, as a rule, everything ends up replacing the radiator.

Engine overheating can occur due to insufficient coolant level, weak fan belt tension, clogged radiator pipes, or if the thermostat is malfunctioning.

To eliminate the malfunction, restore the fluid level in the cooling system, adjust the fan belt tension, flush the radiator, and replace the thermostat.

Often, overheating of the engine also occurs with serviceable elements of the cooling system, when the machine is moving at low speed and high loads on the engine. This happens when driving in heavy road conditions, such as country roads and all boring city traffic jams. In these cases, you should think about the engine of your car, and about yourself too, arranging periodic, at least short-term "respites".

Be careful while driving and avoid emergency mode engine running!

Remember that even a single overheating of the engine breaks the metal structure,
this significantly reduces the life span of the "heart" of the car.

Cooling system operation.

When operating the vehicle, you should periodically look under the hood. Even if you are a philologist by education and have not hammered a single nail in this life, you can still see something and take timely measures to prolong the life of your car.

If the coolant level in the expansion tank has dropped or there is no liquid at all, then first you need to top up it, and then figure it out (on your own or with the help of a specialist) with where it went.

During the operation of the engine, the liquid is heated to a temperature close to the boiling point, which means that the water in its composition will gradually evaporate. If after six months of daily operation of the car, the level in the tank has dropped slightly, then this is normal. But if yesterday there was a full tank, and today it is only on the bottom, then you need to look for the place of the coolant leak.

Leakage of fluid from the system can be easily identified by dark spots on the asphalt or snow after more or less long parking. Once the hood is opened, you can easily locate the leak by comparing the wet marks on the asphalt with the location of the cooling system elements under the hood.

It is necessary to control the level of liquid in the tank at least once a week and if there are leaks, then it is necessary to top up, find and eliminate the cause of the decrease in the level. In other words, you need to put in order the cooling system of your engine. Otherwise, he may become seriously "ill" and require "hospitalization".

Almost all domestic cars use a special low-freezing liquid called TOCOL A-40 as a coolant. The figure (minus 40 o indicates the temperature at which the liquid begins to freeze (crystallize). In the conditions of the far north, TOSOL A-65 is used, and accordingly it will begin to freeze at a temperature of minus 65 o.

TOSOL A-40 is a mixture of water with ethylene glycol and additives. Such a solution combines a lot of advantages. In addition to the fact that it begins to freeze only after the driver himself has frozen (just kidding), TOSOL also has anti-corrosion, anti-foaming properties and practically does not form deposits in the form of ordinary scale, since it contains pure distilled water. Therefore, only distilled water can be added to the cooling system.

When operating a car, it is necessary to control not only the tension, but also the condition of the water pump drive belt, since its breakage on the road is always unpleasant. It is recommended that you carry a spare belt with you. If not yourself, then someone from the "gentlemen" on the road will help you change it.

The coolant can boil and damage the engine if the fan motor sensor fails. Since the electric fan has not received the command to turn on, the liquid continues to heat up, approaching the boiling point, without cooling help. But the driver has a device with an arrow and a red sector in front of his eyes! Moreover, almost always when the fan is turned on, some vibration and a little additional noise are felt. There would be a desire to control, but there will always be ways.

It is especially unpleasant when the engine "boils" while driving off-road at low speed in hot summer. Therefore there is practical advice for those who like to explore the hinterland of their native land and also know how to hold a screwdriver in their hands.

If you add another toggle switch in the car (or use a free one), with which you can manually turn on the electric fan of the cooling system, then the failed sensor will not interrupt your trip. By monitoring the coolant temperature on the instrument, you can decide when to turn on and when to turn off the fan.

If on the way (and more often in a "traffic jam") you notice that the coolant temperature is approaching a critical one, and the fan is working, then in this case there is a way out. It is necessary to include an additional radiator in the operation of the cooling system - a radiator for the interior heater. Fully open the heater tap, turn on the heater fan at all turns, lower the door windows and sweat to the house or to the nearest car service. But continue to closely follow the arrow on the engine temperature gauge. If it enters the red zone, stop immediately, open the hood and “cool down”.

Over time, the thermostat can cause trouble if it stops letting fluid through a large circle of circulation. Determining if the thermostat is working is easy. The radiator should not heat up (determined by hand) until the arrow of the coolant temperature gauge has reached the middle position (the thermostat is closed). Later, hot liquid will begin to flow into the radiator, quickly heating it, which indicates the timely opening of the thermostat valve. But if the radiator continues to be cold, then there are two ways. Knock on the thermostat body, maybe it will open after all, or immediately, morally and financially, prepare for its replacement.

Immediately "surrender" to the mechanic if oil dipstick you will see droplets of fluid from the cooling system into the lubrication system. This means that the cylinder head gasket is damaged and the coolant enters the oil pan of the engine crankcase. If you continue to operate the engine with oil, half consisting of TOSOL, then the wear of engine parts becomes catastrophic. And this, in turn, is already associated with a very expensive repair.

The water pump bearing does not suddenly break. First, there will be a specific whistling sound from under the hood, and if the driver “thinks about the future”, he will promptly replace the bearing. Otherwise, it will still have to be changed, but after being late for the airport or for a business meeting, because of a "suddenly" broken down car.

Each of the drivers should be aware and remember that on a hot engine, the cooling system is in a state high blood pressure! If the engine of your car is overheated and "boiled", then, of course, you need to stop and open the hood of the car, but I do not advise you to open the radiator cap. To speed up the engine cooling process, this will practically do nothing, but you can get severe burns.

Everyone knows what a clumsily open bottle of Champagne turns into for smartly dressed guests. Everything in a car is much more serious. If you quickly and thoughtlessly open the stopper of a hot radiator, then a fountain will fly out, but not wine, but boiling ASTOLA! In this case, not only the driver may be injured, but also pedestrians nearby. Therefore, if you ever have to open the cap of a radiator or expansion tank, then you should first take precautions and do it slowly.

Hence, we can conclude that the driver of that foreign car not only had a short driving experience, but he had not read this book yet! However, this is his misfortune, this should not happen to our reader!

TO Category:

Cars and tractors

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The main elements of the liquid cooling system

Cooling jacket - The space between the double walls of the block and the cylinder head, or between the walls of the block and wet liners.

To ensure uniform cooling of all cylinders, liquid enters the cooling jacket through a distribution pipe that runs along the top of the cylinder block. There are openings in the pipe to supply fluid primarily to the hottest parts of the engine. V-shaped six- and eight-cylinder engines do not have distribution pipes, since in each row these engines have only three to four cylinders.

The radiator serves to cool the fluid coming from the cooling jacket. The radiator (Fig. 37, a) consists of upper and lower reservoirs (tanks) and a core, in which the liquid is cooled. The tanks have branch pipes connected to the engine branch pipes. The upper tank has a neck (through which liquid is poured), closed with a stopper. A steam pipe is soldered inside the tank or in the neck. which removes steam from the system in the event of a boiling liquid, preventing an increase in pressure in the system. In the lower tank or in the branch pipe, a tap is mounted to drain the liquid from the radiator.

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Figure: 36. Cooling system of the SMD-14 engine

The cores of radiators are tubular-lamellar, tubular-tape and lamellar (Fig. 37, b, c, d). To give the radiator more strength, hard sides are soldered on both sides of the core. The radiator is mounted in a frame (see Fig. 37, a), which is attached to the transverse frames on rubber cushions or on springs, which provide softness and elasticity of the fastening.

The radiator tank nozzles are connected to the engine nozzles with flexible hoses, which are fixed to the nozzles with clamping clamps.

The filler neck of the radiator is closed with a special plug (Fig. 38, a), which has a steam and air valves. The steam outlet pipe is soldered on the side into the neck above the plug valves. In the event of a vacuum of 0.002-0.01 MPa, the air valve opens and lets air from the atmosphere into the upper tank. The steam valve opens and releases steam from the upper tank into the atmosphere through the steam outlet pipe when the excess pressure in it rises to 0.03 MPa (Fig. 38, b). The plug with a steam-air valve is unified for most domestic cars and tractors.

On some tractor engines, the steam-air valve is housed in a separate housing that is attached to the upper radiator reservoir.

To regulate the intensity of blowing of the radiator with the counterflow of air, louvers or curtains of the radiator are used. They consist of separate flap plates (Fig. 39), hinged in front of the radiator. With the help of a rod / and a system of levers, the plates are rotated around their axis through an angle of up to 90 °.

The water pump is used for forced circulation of the coolant. On engines with forced cooling, centrifugal pumps of large capacity are installed, creating a pressure on the discharge line from 0.05 to 0.2 MPa. In most engine models, the water pump is mounted on the same shaft as the fan and is driven from the crankshaft by a V-belt drive.

Figure: 37. Radiator of the cooling system

Figure: 38. Radiator cap:
a - the steam valve is open; b - air valve is open

Figure: 39. Radiator blinds

The schematic diagram of the pump is shown in fig. 40, a. The water entering the nozzle is picked up by the impeller blades and is thrown by centrifugal force into the outlet nozzle, which is located tangentially to the pump casing.

The pump shaft (Fig. 40, b) rotates in two ball bearings with seals to keep the lubricant in the bearings and protect them from contamination. The exit point of the rear end of the shaft from the bearing housing is sealed with a collar, which consists of a graphitized textolite washer, a rubber spring seal with two clips. The cavity between the bearings is filled with grease through an oiler. At the rear end of the shaft is an impeller that rotates in the pump housing. The fan hub is attached to the front end of the shaft using a split taper bushing and a key. This fastening makes it possible to tighten the hub while loosening the seating of the pulley. The pump and fan are driven by V-belts.

When the pump is running, the coolant flows through the inlet pipe from the lower radiator tank into the housing. When the impeller rotates, the liquid is thrown by centrifugal force to the walls of the housing and through the outlet channel under pressure enters the engine cooling jacket and then into the upper radiator tank.

The fan is used to create airflow that cools the fluid in the radiator and the surface of the engine.

The fan consists of a shaft with a pulley and blades, which is mounted on bearings in a common housing with a water pump. A hub is attached to the outer end of the shaft, to which the pulley and fan are attached. According to the number of blades, fans are of two, four, five, six and eight blades. The most widespread are fans with four and six blades. The fan is installed behind the radiator in front of the engine. In order to create a directed air flow, a directing cover is often installed, significantly increasing the cooling intensity. To reduce vibration and noise, the fan blades are positioned crosswise, in pairs at angles of 70 ° or 110 °. The blades are stamped from sheet steel with a thickness of 1.25-1.8 mm and are attached to the pulley hub. The blade width usually does not exceed 70 mm.

Figure: 40. Water pump and fan of the ZIL-130 engine:
a - schematic diagram; b - pump and fan design

On new models of KamAZ GAZ and other cars, in order to accelerate engine warm-up in winter, fans with mechanisms for turning them off are installed.

Fans are made in conjunction with a water pump (ZIL-130, GAZ-53A, MTZ-80, DT-75M, etc.) or separately from it (YaMZ-236, YaMZ-238, etc.).

The pump and fan are driven by a V-belt drive from the crankshaft pulley. Fan gear drive is applied in diesel engines YAME-236 and YMZ-238. The belt tension is adjusted by changing the position of the generator pulley (ZIL-130, DT-75M, MTZ-80, etc.), a screw tensioner (D-130, D-108, etc.) or a tension roller (GAZ-53A, etc.) ).

Figure: 41. Hydraulic clutch for the fan drive of the YaMZ-740 engine

To maintain the most favorable thermal conditions of the YaMZ-740 engine, the fan is driven by means of a hydraulic coupling, which turns on and off automatically depending on the temperature of the liquid in the cooling system. With this design, the fan is mounted on the driven shaft of the fluid coupling, which is attached to the front of the engine block and is driven into rotation. crankshaft motor using a hydraulic coupling drive shaft.

The fluid coupling consists of leading and driven parts located in the cavity formed by the front cover and the body (Fig. 41).

The leading part of the fluid coupling, rotating on ball bearings, consists of a drive wheel assembly with a casing, a drive shaft and a hub with a pulley.

The driven part of the fluid coupling, rotating on ball bearings, consists of a driven wheel connected to the driven shaft, on which the fan hub is fixed.

The inner surfaces of the drive and driven wheels have blades. The fluid coupling cavity is sealed with rubber cuffs.

When the engine is running, the oil coming from the lubrication system falls on the blades of the rotating drive wheel. Particles of oil, entrained by the blades of the driving wheel, hitting the blades of the driven wheel, provide rotation of the driven parts and the fan. The rotational speed of the driven wheel with a fan depends on the amount of oil entering the fluid coupling cavity.

The adjustment of the fan operating mode depending on the temperature of the liquid in the cooling system is carried out by the hydraulic coupling switch. It provides connection or disconnection of the drive shaft with the driven shaft by adjusting the oil flow through the fluid coupling, and at the same time turning on or off the fan installed on the driven shaft of the fluid coupling.

The spool type fluid coupling switch is located on the coolant supply pipe to the right side of the cylinders. It has a thermal power element filled with an active mass that melts with an increase in the coolant temperature. When the temperature of the liquid rises to 80-95 ° C, the volume of the active mass will increase so much that the rod under its action will move the switch valve and open the passage for oil from the engine pump to the fluid coupling cavity. Filling the fluid coupling cavity with oil ensures the transmission of rotation from the drive wheel to the driven wheel. The driven wheel of the clutch increases its rotation frequency, and at the same time increases the fan rotation speed. This increase is very smooth and the fan evenly increases the speed of the air passing through the radiator. With a decrease in the supply of oil to the fluid coupling cavity, its volume becomes insufficient to transfer rotation to the drive and driven wheels of the fluid coupling, since a passage is open for oil from its cavity to drain into the engine sump. When the oil supply to the fluid coupling cavity is completely stopped, it ceases to transmit rotation to the fan.

The thermostat serves to automatically regulate the temperature of the liquid in the cooling system by changing the intensity of its circulation through the radiator and accelerating the engine warm-up after starting.

Thermostats are available with one and two valves, liquid and solid filling. Liquid thermostats were previously used on automotive engines, and now solid-filled thermostats are installed.

A liquid thermostat (Fig. 42, a) consists of a corrugated cylinder filled with a low-boiling liquid (at 75-85 ° C), a housing with windows, a main and bypass valves.

When the coolant temperature is below 70 ° C, the cylinder is compressed and the main valve is closed. The bypass coolant flows back to the water pump through two windows, bypassing the radiator, thereby achieving quick warm-up engine.

When the temperature of the liquid rises above 70 ° C, its evaporation begins in the corrugated cylinder and the pressure in it rises. Under the influence of the increased pressure, the main valve rises, opening the access of the coolant from the cooling jacket to the radiator through the branch pipe. Simultaneously with the lift of the main valve, the bypass valve also rises, gradually closing the window and stopping the access of coolant to the bypass channel. At a coolant temperature of 81-85 ° C, circulation through the bypass channel stops and liquid enters the radiator only through the branch pipe.

A thermostat with a solid filler consists of a copper balloon (Fig. 42, b) filled with an active mass consisting of ceresin (petroleum wax) mixed with copper powder. The bottle is closed with a lid with a rubber membrane. A stem rests on the membrane, which is pivotally connected to a flap mounted on a hinged support in the throat of the water pipe. When the engine is cold, the damper is constantly pressed against the edges of the throat by a spring and the coolant circulates bypassing the radiator, accelerating the engine warming up. When the coolant reaches a temperature of 70-85 ° C, the ceresin in the thermostat cylinder melts and, increasing its volume, moves the rod with a rubber buffer upward, opening the damper 15. The coolant circulates through the radiator.

When the temperature drops, the active mass decreases its volume and the damper is closed under the action of the spring. The circuit of the coolant circulation at different positions of the thermostat valve is shown in Fig. 43.

The liquid is drained from the cooling system with the radiator plug removed through the drain taps on the radiator and on the block. Have V-shaped engines there are two taps (see fig. 35) on the block and the third on the radiator pipe. Starting heater also equipped with a drain cock.

Figure: 42. Thermostats:
a - liquid type: b - with solid filler

Figure: 43. Circulation diagram of the coolant in the cooling system:
a - with the thermostat valve closed (small circle of circulation); b - with the valve open (large circle of circulation)

The elements of the liquid cooling system are connected using steel pipes, cast iron pipes and rubberized flexible hoses with clamps. This connection allows for relative displacement of the engine and radiator.

The condensation (expansion) tank compensates for the change in the volume of the liquid when it is heated, helps to remove air from the coolant and condense the vapor entering it from the cooling system.

The expansion tank (fig. 44) is connected by a bypass pipe to the upper radiator tank. A valveless plug is installed on the upper radiator tank, and a plug with valves, the design of which is shown in Fig. 1, is installed on the condensation tank. 38. The tank has a drain cock and a steam pipe. When the coolant boils, steam flows through a pipe into the expansion tank and condenses while mixing with the liquid in the tank. As the temperature drops, a vacuum is created in the tank. This opens inlet valve plugs and air enters the tank, and coolant from the expansion tank replenishes the system. Due to the presence of a reservoir in the radiator, required level liquids.

Control over the temperature in the cooling system is carried out according to the indications of electric indicators of water temperature, as well as alarm indicators.

Figure: 44. Expansion tank

Engine cooling system internal combustion designed to remove excess heat from engine parts and assemblies. In fact, this system is bad for your pocket. Approximately one third of the heat obtained from the combustion of the precious fuel has to be dissipated in the environment. But such is the structure of a modern internal combustion engine. The ideal would be an engine that can operate without heat dissipation in environment, and turn it all into useful work... But the materials used in modern engine building will not withstand such temperatures. Therefore, at least two basic, basic engine parts - the cylinder block and the block head - have to be additionally cooled. At the dawn of the automotive industry, two cooling systems appeared and competed for a long time: liquid and air. But the air cooling system gradually gave up its positions and is now used mainly for very small engines motor vehicles and generator sets low power... Therefore, let's take a closer look at the liquid cooling system.

Cooling system device

Cooling system of modern car engine Includes engine cooling jacket, coolant pump, thermostat, connecting hoses and radiator with fan. The heater heat exchanger is connected to the cooling system. Some engines also use coolant to heat the throttle assembly. Also, in engines with a supercharged system, there is a supply of coolant to the liquid-air intercoolers or to the turbocharger itself to reduce its temperature.

The cooling system works quite simply. After starting a cold engine, the coolant begins to circulate in a small circle using a pump. It passes through the cooling jacket of the block and cylinder head of the engine and returns to the pump through the bypass (bypass) pipes. In parallel (on the vast majority of modern cars), the liquid is constantly circulating through the heater heat exchanger. As soon as the temperature reaches the set value, usually around 80–90 ° C, the thermostat starts to open. Its main valve directs the flow to the radiator, where the liquid is cooled by the counterflow of air. If the air blowing is not enough, then the cooling system fan comes into operation, in most cases having an electric drive. The movement of fluid in all other components of the cooling system continues. The bypass channel is often an exception, but it does not close on all vehicles.

Cooling systems have become very similar to each other in recent years. But two fundamental differences remain. The first is the location of the thermostat before and after the radiator (in the direction of fluid flow). The second difference is the use of a pressurized circulating expansion tank, or an unpressurized tank, which is a simple reserve volume.

Using the example of three schemes of cooling systems, we will show the difference between these options.

Components

Cylinder head and block jacket are channels cast in an aluminum or cast iron product. The channels are sealed, and the joint between the block and the cylinder head is sealed with a gasket.

Coolant pump blade, centrifugal type. Driven by either a timing belt or drive belt auxiliary units.

Thermostatis an automatic valve that is triggered when a certain temperature is reached. It opens, and part of the hot liquid is discharged into the radiator, where it cools down. Recently they began to use electronic control this simple device... They began to heat the coolant with a special heating element to open the thermostat earlier if necessary.

Fluid change and flushing

If you did not have to replace any unit in the cooling system earlier, then the instructions recommend changing the antifreeze at least every 5-10 years. If you did not have to add water to the system from a canister, and even worse - from a roadside ditch, then when changing the fluid, the system does not need to be flushed.

But if the car has seen a lot in its lifetime, then it is useful to make it when changing the fluid. Having opened the system in several places, you can thoroughly rinse it with a stream of water from a hose. Or just drain the old liquid and fill in the clean one, boiled water... Start the engine and warm up to operating temperature. After waiting for the system to cool down, so as not to burn yourself, drain the water. Then purge the system with air and add fresh antifreeze.

Flushing the cooling system is usually started in two cases: when the engine overheats (this is manifested primarily in summer period) and when the stove stops heating in winter. In the first case, the reason lies in the radiator pipes overgrown with dirt on the outside and clogged from the inside. In the second, the problem is that the heater radiator tubes are clogged with deposits. Therefore, during a scheduled fluid change and when replacing components of the cooling system, do not miss the opportunity to thoroughly flush all the components.

Tell us what kind of cooling system malfunctions you encountered. And I wish you a hot heater in winter and good cooling in summer.

Purpose and device of the engine cooling system

The cooling system is designed to cool the engine parts during its operation and maintain a normal temperature, the most favorable thermal regime of the engine. Exist liquid cooling, air cooling and combined cooling.

Overheating of the engine worsens the quantitative filling of the cylinder with a combustible mixture, causes dilution and oil burnout, as a result of which the pistons in the cylinders can jam and the bearing shells melt.

Overcooling of the engine causes a decrease in engine power and economy, gasoline vapors condense on cold parts and drip down the cylinder mirror in the form of drops, washing off the lubricant, friction losses increase, wear of parts increases and there is a need for frequent replacement oils. And also incomplete combustion of fuel occurs, which is why a large layer of carbon deposits forms on the walls of the combustion chamber - possibly the valves hang.

For normal work engine coolant temperature should be 80-95 degrees.

The heat balance can be represented as a diagram.

Figure: Thermal balance diagram of an internal combustion engine.

On engines domestic production a closed forced liquid cooling system is used, carried out by a water pump. It does not directly communicate with the atmosphere, therefore it is called closed. As a result, the pressure in the system increases, the boiling point of the coolant rises to 108 - 119 degrees and the consumption for its evaporation decreases.

These cooling systems provide even and efficient cooling and also produce less noise.

Consider the cooling system using the example of a ZIL engine

Figure: The scheme of the cooling system of the ZIL type engine. 1 - radiator, 2 - compressor, 3 - water pump, 4 - thermostat, 5 - heater tap, 6 - inlet pipe, 7 - outlet pipe, 8 - heater radiator, 9 - water temperature gauge sensor in the engine cooling system, 10 - drain valve of the cylinder block jacket (in the "open" position), 11 - drain valve of the radiator.

The liquid in the engine cooling jacket heats up due to the removal of heat from the cylinders, flows through the thermostat into the radiator, is cooled in it and under the influence centrifugal pump(circulates the coolant in the system) returns to the engine jacket. The people call the centrifugal pump "pump". Cooling of the liquid is facilitated by the intensive blowing of the radiator and the engine by the air flow from the fan. Fanenhances air flow through the radiator core, serves to improve the cooling of the liquid in the radiator. The fan can have a different drive.

– mechanical- permanent connection with the engine crankshaft,

– hydraulic- fluid coupling. The fluid coupling includes a hermetic casing B filled with liquid.

The casing houses two spherical vessels D and D, rigidly connected to the driving shaft A and driven shaft B, respectively.

Figure: Hydraulic coupling, and - principle of operation; b - device, 1 - cylinder block cover, 2 - housing, 3 - casing, 4 - drive roller, 5 - pulley, 6 - fan hub, A - drive shaft, B - driven shaft, C - casing, D, D - vessels, T - turbine wheel, H - pump wheel.

The operating principle of the hydraulic fan is based on the centrifugal force of the fluid. If a spherical vessel D filled with liquid rotates with high speed, the liquid enters the second vessel G, forcing it to rotate. Having lost energy upon impact, the liquid returns to vessel D, accelerates in it, enters vessel D, and the process is repeated.

– electric- controlled electric motor. When the coolant temperature reaches 90-95 degrees, the sensor valve opens oil channel in the switch housing and motor oil enters the working cavity of the fluid coupling from the main lubrication system of the engine.

The fan is enclosed in a casing mounted on the radiator frame, which increases the air flow rate through the radiator.

Radiatorserves to cool the water coming from the engine water jacket.

Figure: Radiator a - device, b - tubular middle, c - plate middle, 1 - upper tank with a branch pipe, 2 - steam outlet pipe, 3 - filler neck with a plug, 4 - core, 5 - lower tank, 6 - branch pipe with a drain cock, 7 - tubes, 8 - transverse plates.

Consists of top 1 and bottom 5 tanks and core 4 and fastening parts. The tanks and core are made of brass (to improve thermal conductivity).

The most common are tubular and plate radiators. For tubular radiators, shown in figure "b" - the core is formed from a row of thin horizontal plates 8, through which many vertical brass tubes pass, due to which water, passing through the core of the radiator, breaks up into many small streams. The horizontal plates serve as additional stiffeners and increase the cooling surface.

Plate radiators consist of one row of flat brass tubes, each of which is made of corrugated plates welded together along the edges.

Thermostatserves to accelerate the warm-up of a cold engine and ensure optimal temperature conditions. The thermostat is a valve that regulates the amount of fluid passing through the radiator.

When starting the engine, the engine itself and its coolant are cold. To speed up engine warm-up, the coolant moves in a circle, bypassing the radiator. At the same time, the thermostat is closed, as the engine heats up (to a temperature of 70-80 degrees), the thermostat valve, under the action of the vapor of the liquid filling its cylinder, opens and the coolant begins to move in a large circle through the radiator.

On modern cars establish dual-circuit cooling systems... This system includes two independent cooling circuits:

- cooling circuit of the cylinder block;

- the cooling circuit of the cylinder head.

From the book Determining and fixing faults on your own in a car author Zolotnitsky Vladimir

The engine exhaust is smoky. An increased volume of gases enters the crankcase of the engine. Diagnosing the engine by the color of the smoke from the exhaust pipe. Blue-white smoke - unstable engine operation. The valve chamfer is burnt. Assess the condition of the gas distribution

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Engine lubrication system malfunctions Oil pressure drop at any crankshaft speed Faulty oil pressure gauge or gauge. Make sure it works control lamp (oil pressure gauge) and sensor. Disconnect the wire from the sensor

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Armored attack aircraft with motors air cooling: option P.O. Sukhoi The famous Soviet Il-2 attack aircraft designed by S. V. Ilyushin, which became the most massive aircraft in the history of Russian aviation, was equipped with an AM-38 (AM-38F) liquid-cooled engine.

From the book Aviation and Cosmonautics 2001 05-06 author

The device and principle of operation or starting the engine "for free" Among technical means, ensuring confident engine start in winter, one original stands out, literally requiring no additional energy. This device is a heat accumulator, or how

From the book We Maintain and Repair Volga GAZ-3110 author Zolotnitsky Vladimir Alekseevich

WITH AIR COOLED MOTOR IL-2 M-82. Factory tests, 1941 In order to expand the engine base of the Il-2 and increase its combat survivability S.V. Ilyushin on July 21, 1941 turned to the People's Commissariat of the aircraft industry A.I.Shakhurin (letter No. 924) with a proposal to install it on an aircraft

From the BIOS book. Express course author Traskovsky Anton Viktorovich

Engine lubrication system malfunctions

From the book Trucks. Supply system author Melnikov Ilya

Chapter 1 Purpose and structure of BIOS Why BIOS is needed If we consider a personal computer as a kind of living organism, then BIOS (Basic Input / Output System) is the subconscious of a computer. Like human reflexes, this system "forces" the computer

From the book Trucks. Cooling and lubrication systems author Melnikov Ilya

Servicing the fuel system of the carburetor engine Check the fuel system daily to check for leaks and, if necessary, refuel the car. technical service (TO-1, TO-2). - Check the fixing of devices,

From the book Trucks. History and development author Melnikov Ilya

Trucks. Cooling and lubrication systems

From the book Boat. Device and management author Ivanov L.N.

Cooling system

From the book Materials Science. Crib author Buslaeva Elena Mikhailovna

The main malfunctions of the cooling system Symptoms of malfunction: hypothermia or overheating of the engine. optimum temperature coolant, good thermal conductivity of the walls of the water jackets and radiator tubes.

From the author's book

Cooling system maintenance 1. Check the system for leaks every day. Eliminate the malfunction if necessary. Check the liquid in the vehicle cooling system daily. Add fluid if necessary. Her level should be lower

From the author's book

Lubrication system. Purpose and design The engine lubrication system is necessary for the continuous supply of oil to the rubbing surfaces of the parts and the removal of heat from them. The surfaces of the mating parts of the engines are distinguished by high accuracy and cleanliness of processing. but

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Appointment and general arrangement car body Most passenger cars have a so-called load-bearing body on which the engine, transmission units, suspension of the chassis are installed, optional equipment... Have trucks, buses,

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22. System with unlimited solubility in liquid and solid states; systems of eutectic, peritectic and monotectic type. Systems with component polymorphism and eutectoid transformation Complete mutual solubility in the solid state is possible

Let us recall a little more about this cooling system.

IN liquid cooling system special coolants are used - antifreezes of various brands with a thickening temperature of 40 ° C and below. Antifreezes contain anti-corrosion and anti-foaming additives that eliminate the formation of scale. They are highly poisonous and require careful handling. Compared to water, antifreezes have a lower heat capacity and therefore remove heat from the cylinder walls of the engine less intensively.

So, when cooling with antifreeze, the temperature of the cylinder walls is 15 ... 20 ° C higher than when cooling with water. This speeds up engine warm-up and reduces cylinder wear, but summer time may overheat the engine.

Optimal temperature regime the engine with a liquid cooling system is considered such that the temperature of the coolant in the engine is 80 ... 100 ° C at all engine operating modes.

Used in car engines closed (sealed) liquid cooling system forced circulation coolant.

The internal cavity of a closed cooling system does not have a constant connection with the environment, and communication is carried out through special valves (at a certain pressure or vacuum) located in the plugs of the radiator or expansion tank of the system. Cooling liquid in such a system boils at 110 ... 120 ° C. Forced circulation of coolant in the system is provided by a liquid pump.

Engine cooling system consists of:

• cooling jacket for the head and cylinder block;
• radiator;
• pump;
• thermostat;
• fan;
• expansion tank;
• connecting pipelines and drain taps.

In addition, the cooling system includes a heater for the vehicle interior.

How the cooling system works

I propose to consider first schematic diagram cooling systems.

1 - heater; 2 - engine; 3 - thermostat; 4 - pump; 5 - radiator; 6 - cork; 7 - fan; 8 - expansion tank;
A - small circle of circulation (thermostat is closed);
A + B - large circulation circle (thermostat open)

The circulation of the liquid in the cooling system is carried out in two circles:

1. Small circle - the liquid circulates when starting a cold engine, ensuring its rapid warming up.

2.Large circle - the movement circulates when the engine is warm.

Simply put, the small circle is the circulation of the coolant WITHOUT the radiator, and the large circle is the circulation of the coolant THROUGH the radiator.

The design of the cooling system differs in its design depending on the car model, however, the principle of operation is the same.

The principle of operation of this system can be seen in the following videos:

I propose to disassemble the system device according to the sequence of work. So, the beginning of the operation of the cooling system occurs when the heart of this system - the liquid pump - starts up.

1. Liquid pump (water pump)

The liquid pump provides forced circulation of liquid in the engine cooling system. Vane pumps of the centrifugal type are used on car engines.

Search our liquid pump or water pump follows on the front of the engine (the front is the one that is closer to the radiator and where the belt / chain is located).

The liquid pump is connected by a belt to the crankshaft and generator. Therefore, to find our pump, it is enough to find the crankshaft and find the generator. We'll talk about the generator later, but for now I'll just show you what to look for. The generator looks like a cylinder attached to the engine body:

1 - generator; 2 - liquid pump; 3 - crankshaft

So, we figured out the location. Now let's take a look at its structure. Recall that the structure of the entire system and its parts is different, but the principle of operation of this system is the same.

1 - pump cover;2 - The persistent sealing ring of the stuffing box.
3 - Oil seal; 4 - Pump shaft bearing.
5 - the hub of the fan pulley;6 - Locking screw.
7 - pump roller;8 - Pump casing;9 - Pump impeller.
10 - Suction branch pipe.

The work of the pump is as follows: the pump is driven from the crankshaft through a belt. The belt turns the pump pulley, rotating the pump pulley hub (5). That, in turn, drives the pump shaft (7), at the end of which there is an impeller (9). The coolant enters the pump casing (8) through the inlet (10), and the impeller moves it into the cooling jacket (through a window in the casing, as seen in the figure, the direction of movement from the pump is shown by an arrow).

Thus, the pump is driven by the crankshaft, the liquid enters it through the inlet pipe and goes into the cooling jacket.

The operation of the liquid pump can be seen in this video (1:48):

Let's now see, where does the liquid come from to the pump? And the liquid enters through a very important part - the thermostat. It is the thermostat that is responsible for the temperature regime.

2. Thermostat

The thermostat automatically adjusts the water temperature to speed up engine warm-up after starting. It is the operation of the thermostat that determines which circle (large or small) the coolant will go.

This unit looks like this in reality:

How the thermostat works very simple: the thermostat has a sensitive element, inside of which there is a solid filler. At a certain temperature, it begins to melt and opens the main valve, and the additional valve, on the contrary, closes.

Thermostat device:

1, 6, 11 - branch pipes; 2, 8 - valves; 3, 7 - springs; 4 - balloon; 5 - diaphragm; 9 - stock; 10 - filler

The operation of the thermostat is simple, you can see it here:

The thermostat has two inlets 1 and 11, outlet 6, two valves (main 8, additional 2) and a sensitive element. The thermostat is installed in front of the inlet to the coolant pump and is connected to it through branch pipe 6.

Compound:

Acrossbranch pipe 1 connects fromengine cooling jacket,

Across branch pipe 11 - with bottom diverting radiator reservoir.

The sensing element of the thermostat consists of a balloon 4, a rubber diaphragm 5 and a rod 9. Inside the balloon between its wall and the rubber diaphragm there is a solid filler 10 (fine-crystalline wax), which has a high coefficient of volume expansion.

The main valve 8 of the thermostat with a spring 7 begins to open when the coolant temperature is more than 80 ° C. At temperatures less than 80 ° C, the main valve closes the liquid outlet from the radiator, and it enters the pump from the engine, passing through the open additional valve 2 of the thermostat with a spring 3.

When the temperature of the coolant rises above 80 ° C, a solid filler melts in the sensitive element, and its volume increases. As a result, the rod 9 leaves the cylinder 4, and the cylinder moves upward. At the same time, additional valve 2 begins to close and, at a temperature of more than 94 ° C, blocks the passage of the coolant from the engine to the pump. In this case, the main valve 8 opens completely, and the coolant circulates through the radiator.

The operation of the valve is clearly and clearly shown in the figure below:

A - small circle, the main valve is closed, the bypass valve is closed. B - a large circle, the main valve is open, the bypass valve is closed.

1 - Inlet pipe (from the radiator); 2 - Main valve;
3 - Thermostat housing; 4 - Bypass valve.
5 - Branch pipe of the bypass hose.
6 - Branch pipe for supplying coolant to the pump.
7 - Thermostat cover; 8 - Piston.

So, we have dealt with the small circle. Disassembled the device of the pump and thermostat, interconnected. Now let's move on to the big circle and the key element. large circle - the radiator.

3. Radiator (radiator / cooler)

Radiator provides heat removal from the coolant to the environment. On passenger cars tubular-plate radiators are used.

So, there are 2 types of radiators: collapsible and non-collapsible.

Below is their description:

I want to say again about the expansion tank (expansion Tank)

A fan is installed next to the radiator or on it. Let's now move on to the design of this very fan.

4. Fan (fan)

The fan increases the speed and amount of air passing through the radiator. Four- and six-blade fans are installed on car engines.

If a mechanical fan is used,

The fan includes six or four blades (3) riveted to a crosspiece (2). The latter is screwed to the pulley of the liquid pump (1), which is driven by the crankshaft using a belt drive (5).

As we said earlier, the generator (4) is also engaged.

If an electric fan is used,

then the fan consists of an electric motor 6 and a fan 5. The fan is four-bladed, mounted on the shaft of the electric motor. The blades on the fan hub are located unevenly and at an angle to the plane of rotation. This increases the fan flow and reduces the fan noise. For more efficient operation, the electric fan is located in the casing 7, which is attached to the radiator. The electric fan is attached to the casing with three rubber bushings. The electric fan is switched on and off automatically by sensor 3 depending on the coolant temperature.

So let's summarize. Let us not be unfounded and summarize by some picture. You should not focus on a specific device, but the principle of operation must be understood, because it is the same in all systems, no matter how different their device is.

When the engine is started, the crankshaft begins to rotate. Through a belt drive (let me remind you that the generator is also located on it), rotation is transmitted to the pulley of the liquid pump (13). It drives the shaft with the impeller in rotation inside the housing of the liquid pump (16). The coolant flows into the engine cooling jacket (7). Then, through the outlet (4), the coolant returns to the liquid pump through the thermostat (18). At this time, the bypass valve is open in the thermostat, but the main one is closed. Therefore, the liquid circulates through the engine jacket without the involvement of the radiator (9). This allows the engine to warm up quickly. After the coolant heats up, the thermostat main valve opens and the bypass valve closes. Now liquid cannot flow through the thermostat bypass (3) and is forced to flow through the inlet (5) into the radiator (9). There, the liquid is cooled and flows back into the liquid pump (16) through the thermostat (18).

It is worth noting that some of the coolant enters the heater from the engine cooling jacket through port 2 and returns from the heater through port 1. But we will talk about this in the next chapter.

Hopefully the system will now be clear to you. After reading this article, I hope that it will be possible to navigate in another cooling system, having understood the principle of this one.

I also suggest that you familiarize yourself with the following article:

Since we have touched on the heating system, my next article will be about this system.