How a car engine is cooled. Types of cooling systems. Liquid cooling systems - specifics

(hereinafter referred to as the internal combustion engine) is a strict sequence of micro-explosions of combustible mixture in the cylinders. Accordingly, the engine temperature increases, which becomes critical. Such processes inevitably lead to failure power unit any vehicle. That is why all modern internal combustion engines must use a cooling system.

Functions and types of system

The main purpose of the cooling system for both gasoline and diesel internal combustion engine comes down to the forced removal of heat from engine parts that heat up during its operation, and maintaining its operating temperature.
In addition to this function, the car cooling system also performs a number of other related tasks:

1. acceleration of engine warm-up to operating temperature;
2. heating air for interior heating;
3. cooling of the internal combustion engine lubrication system;
4. cooling exhaust gases(when using recirculation);
5. air cooling (with turbocharging);
6. cooling of the lubricant in the gearbox (with automatic transmission).

Depending on the principle of operation and method of operation, it is customary to distinguish the following cooling systems:

• liquid (based on heat removal by liquid flow);
• air (based on cooling by air flow);
• combined (combining the operating principles of liquid and air systems).

System structure

The vast majority of internal combustion engines have a liquid cooling system (closed type), using the principle of forced circulation. It is this that, on the one hand, is capable of providing the most efficient cooling, and on the other hand, it is a more ergonomic and comfortable way to remove excess heat from the engine.


Device and circuit diagram The engine cooling system (both diesel and gasoline) includes the operation of the following components:

1. radiator with fan (electric, mechanical or hydraulic);
2. heater radiator (“stove”) with electric fan;
3. cooling jackets for the cylinder block and cylinder head;
4. circulation (water) pump (“pump”);
5. expansion tank;
6. heater radiator tap;
7. connecting pipes and hoses.

Water, antifreeze, and antifreeze can be used as a coolant. The cooling system of the vast majority of cars uses antifreeze as a more best option, due to the good ratio of cost and functional characteristics.

How the system works

The operating principle of the engine cooling system (both gasoline and diesel) is very simple and is based on targeted circulation of coolant. The coolant, taking heat from the engine parts (in the cooling jackets), under the influence of the pressure created by the water pump, begins to circulate through the system, carrying out heat exchange.

Initially, the fluid moves in a small circle with the thermostat closed, that is, without the radiator operating. This is done in order to speed up the process of warming up the engine and bringing it to operating temperature. After the liquid is returned to the cooling jackets, the circulation process continues.

When the temperature reaches high levels (within 100 degrees), the thermostat opens and the coolant begins to move in a large circle, entering the radiator. This immediately cools the engine, because liquid that was not previously used (which was in the radiator) enters the cooling system. The radiator itself is cooled by the flow of atmospheric air.


When the engine heats up further (for example, in summer period), when the liquid does not have time to cool down to the required temperature level, a special device automatically turns on an electric fan (“sloth”), additionally cooling the radiator and partly the engine. The fan runs until it reaches required level liquid temperature, and a special device turns it off. The mechanical version of the fan, connected to the crankshaft by a belt drive, operates in a constantly operating mode.

If necessary (for example, in the cold season), the coolant enters the “stove” through the open heater tap, where, with the help of a radiator, on the one hand, it additionally cools, giving off excess heat, and on the other, it heats the air in the car interior.

Main system malfunctions

If you look at paragraph 2.3.1 of the traffic rules and the “List of faults...” that restrict the movement of vehicles, you will find a complete absence of mention of problems associated with the engine cooling system. This means that system breakdowns are not positioned as faults for which movement is prohibited. And, therefore, the cooling system and its repair is a personal matter for each driver, the degree of his comfort on the road.

What are the main “non-serious” problems that an internal combustion engine cooling system may experience?

First, the most common is a coolant leak or leak. Moreover, its reasons may be a change in street temperature (more often - the onset of the frost season). Among the popular reasons is coking of pipes and hoses, which, under constant exposure to high temperatures, lose their elasticity. Coolant leakage is also caused by physical damage to the main radiator and the heater radiator, obtained either chemically (for example, by reagents included in antifreeze) or through mechanical action (for example, an impact).


Secondly, an equally popular malfunction is the failure (or jamming) of the thermostat. The thermostat valve (a device in constant contact with the liquid) gradually corrodes. Ultimately, it jams, which prevents operation in the “open-closed” system. The results of such a thermostat condition are twofold:

1. when stuck in the “open” position, the coolant moves only in a large circle (with constant use of the radiator), which leads to weak and prolonged warm-up of the engine and, accordingly, poor heating of the car interior;
2. when stuck in the “closed” position, the coolant, on the contrary, moves only in a small circle (without using a radiator), which causes engine overheating and can lead to irreversible changes in the metal structure, a decrease in the life of the power unit and even its breakdown.

Thirdly, a breakdown of the circulation pump (or “pump”) seems to be a serious nuisance. Most often, this malfunction is associated with the failure of the “pump” bearing - its main part. The reasons are trivial - wear and tear or low-quality spare parts. It is difficult to predict a breakdown, but it is more than possible to detect the beginning of non-standard operation of the “pump” - by the characteristic whistling sound of the bearing. It means that the circulation pump requires immediate replacement.


Fourthly, under certain conditions, the engine cooling system may become clogged. The reasons for this condition are, as a rule, the deposition of salts in the channels of the cooling system (radiator, block, block head). In this case, the circulation of coolant is disrupted and the removal of excess heat from the engine and its parts is impaired. Ultimately, this leads to overheating of the engine with all the ensuing consequences.

Basic system operation and maintenance

Monitoring the condition of the cooling system is necessary condition comfortable movement on the vehicle. Despite the fact that malfunctions of this system do not prohibit the operation of the car, the driver must understand the danger of its failure. Engine overheating, which is more than possible in the warm season, and insufficient heating of the car interior in winter time leads to the need for repairs, sometimes very expensive.
Compliance with the basic rules for operating the engine cooling system will allow you to avoid, prevent in time or minimize the impact of malfunctions on the normal operation of the car.

Constant monitoring of coolant level

The expansion tank serves to visually monitor the fluid level in the cooling system. The fact is that the volume of the cooling system is constant, but the volume of liquid varies depending on operating conditions. When the coolant level (indicated on the expansion tank) decreases or increases, it is necessary to adjust its amount in the system.

Diagnosis of system leaks

A constant decrease in the coolant level is most often associated with its leakage. Numerous connections of pipes with elements of the cooling system, corrosion of the main radiator or heater radiator lead to a constant decrease in the liquid level in the expansion tank. Diagnosing the problem involves detecting dark spots on components and assemblies located in engine compartment, wet footprints on the roadway, as well as the characteristic sweetish-sweet smell of antifreeze. More serious is the detection of traces of antifreeze on the oil dipstick, which leads to expensive engine repairs.

Symptoms of engine overheating or underheating

Overheating can be due to several reasons:

1. the thermostat is stuck in the “closed” position;
2. clogging of system channels;
3. insufficient fluid level in the system.

But insufficient heating of the car engine exclusively indicates a jammed thermostat, which only works in the “open” position.

Summarize. The engine cooling system performs the functions of removing excess heat from the power unit generated during operation and maintaining the normal (operating) mode of its operation.

Engine operation internal combustion(ICE) leads to excessive heating of all its parts and without cooling them, the operation of the main unit of the vehicle is impossible. This role is performed by the engine cooling system, which is also responsible for heating the car interior. In turbocharged engines, it helps reduce the temperature of the air forced into the cylinders, and in automatic transmissions, this system cools the fluid that is used to operate it. Selected models machines are equipped with an oil cooler, which takes part in the thermoregulation of the oil used to lubricate the engine.

The engine cooling system can be air or liquid

Both of these systems are not ideal and have both advantages and disadvantages.

Advantages of an air cooling system:

• light weight of the engine;
• simplicity of the device and its maintenance;
• low demands on temperature changes.

Disadvantages of an air cooling system:

• a lot of noise from the engine;
• overheat individual parts motor;
• inability to line up cylinders in blocks;
• difficulty in using the generated heat to heat the car interior.

In modern conditions, automakers prefer to equip their cars primarily with engines with liquid cooling systems. Air structures that cool engine components are very rare.

Advantages of a liquid cooling system:

• less noisy engine compared to the air system;
• high start-up speed when starting the engine;
• uniform cooling of all parts of the power mechanism;
• less prone to detonation.

Disadvantages of a liquid cooling system:

• expensive maintenance and repairs;
• possible leakage of liquid;
• frequent engine hypothermia;
• freezing of the system during periods of frost.

Structure of a liquid engine cooling system

The main components of the liquid cooling system of the internal combustion engine include the following parts:

• engine water jacket
• fan;
• radiator;
• pump (centrifugal pump);
• thermostat;
• expansion tank;
• heater heat exchanger;
• constituent controls.

The engine water jacket is the plane between the walls of the unit in those places that require cooling.

The cooling system radiator is a mechanism that is designed to release the heat generated by the operation of the engine. The unit is a structure made of many curved aluminum pipes, which also have additional fins that promote greater heat transfer.

The fan is used to speed up the circulation of air around the radiator. The fan turns on when the coolant reaches the limit of heating.

A centrifugal pump (in other words, a pump) ensures continuous movement of fluid while the engine is running. The drive for the pump can be different: belt, for example, or gear. On cars with turbocharged engines, additional pumps are often installed that promote fluid circulation and are started from the control unit.

A thermostat is a device in the form of a bimetallic (or electronic) valve located between the radiator inlet and the “cooling jacket”. This device provides the required temperature of the liquid used to cool the internal combustion engine. When the engine is cool, the thermostat is closed, so forced circulation of the cooling liquid passes inside the engine without affecting the radiator. When the liquid reaches the limit temperature, the valve opens. At this moment the system begins to function at its full potential.

The expansion tank is used to fill the coolant. This unit also compensates for changes in the amount of liquid in the system during temperature changes.

A heater radiator is a mechanism designed to heat the air in the vehicle interior. His working fluid is collected directly near the entrance to the motor “jacket”.

The main element of coordination of the internal combustion engine cooling system is a sensor (temperature), the electronic unit controls, as well as actuators.

Features of the engine cooling system

The cooling system operates under the control of the powertrain control system. The pump starts the circulation of liquid in the “cooling jacket” of the engine. Depending on the degree of heating, the liquid moves either in a small or large circle.

In order for the engine to warm up faster after starting, the fluid circulates in a small circle. After it is heated, the thermostat opens, allowing the liquid to circulate through the radiator, at the outlet of which the liquid is exposed to an air flow (counter flow or from a running fan), which cools it.

Turbocharged engines can use a dual-circuit cooling system. The peculiarity of its operation is that one circuit controls the cooling of the charge air, and the second controls the cooling of the engine.

Purpose and design of the engine cooling system

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

Engine overheating impairs the quantitative filling of the cylinder with the combustible mixture, causes dilution and burnout of the oil, as a result of which the pistons in the cylinders can jam and the bearing liners melt.

Engine overcooling causes a decrease in engine power and efficiency, gasoline vapors condense on cold parts and flow down the cylinder surface in the form of drops, washing away the lubricant, friction losses increase, wear of parts increases and the need for frequent replacement oils Incomplete combustion of the fuel also occurs, which causes a large layer of soot to form on the walls of the combustion chamber - possibly causing the valves to hang.

For normal engine operation, the coolant temperature should be 80-95 degrees.

The heat balance can be represented as a diagram.

Rice. Diagram of the thermal balance of an internal combustion engine.

Domestic engines use a closed forced liquid cooling system, 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 uniform and efficient cooling and also produce less noise.

Let's consider the cooling system using the example of a ZIL engine

Rice. Diagram of the ZIL engine cooling system. 1 – radiator, 2 – compressor, 3 – water pump, 4 – thermostat, 5 – heater valve, 6 – inlet pipe, 7 – outlet pipe, 8 – heater radiator, 9 – water temperature indicator sensor in the engine cooling system, 10 – drain valve of the cylinder block jacket (in the “open” position), 11 – radiator drain valve.

The liquid in the engine cooling jacket is heated by heat removal from the cylinders, enters through the thermostat into the radiator, is cooled in it and under the influence of centrifugal pump(circulates coolant in the system) returns to the engine jacket. A centrifugal pump is popularly called a “pump”. Cooling of the liquid is facilitated by intensive air flow from the fan to the radiator and engine. Fan enhances air flow through the radiator core, serves to improve cooling of the fluid in the radiator. The fan can have a different drive.

– mechanical– permanent connection with crankshaft engine,

– hydraulic– hydraulic coupling. The fluid coupling includes a sealed housing B filled with liquid.

The casing contains two spherical vessels D and G, rigidly connected to the driving A and driven B shafts, respectively.

Rice. Fluid coupling, a – principle of operation; b – device, 1 – cylinder block cover, 2 – housing, 3 – casing, 4 – drive shaft, 5 – pulley, 6 – fan hub, A – drive shaft, B – driven shaft, C – casing, D, D – vessels, T – turbine wheel, N – pump wheel.

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

– electric– controlled electric motor. When the coolant temperature reaches 90-95 degrees, the sensor valve opens the oil channel in the switch housing and engine 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 speed of air flow passing through the radiator.

Radiator serves to cool the water coming from the engine water jacket.

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

Consists of upper 1 and lower 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. The tubular radiators shown in figure “b” have a core formed from a series of thin horizontal plates 8, through which many vertical brass tubes pass, due to which the water passing through the core of the radiator is broken into many small streams. 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 at the edges.

Thermostat serves to speed up 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. In this case, the thermostat is closed, as the engine heats up (to a temperature of 70-80 degrees), the thermostat valve, under the influence of liquid vapors filling its cylinder, opens and the coolant begins its movement in a large circle, through the radiator.

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

– cylinder block cooling circuit;

– cylinder head cooling circuit. This text is an introductory fragment.

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Currently, all progressive humanity uses one or another for transportation. automobile transport (cars, buses, trucks).

The Russian encyclopedic dictionary interprets the word car (from auto - mobile, easily moving), a transport trackless vehicle, mainly on wheels, driven by its own engine (internal combustion, electric or steam).

There are vehicles: passenger (cars and buses), cargo, special (firefighting, ambulance and others) and racing.

The growth of the country's automobile fleet caused a significant expansion of the network of automobile maintenance and repair enterprises and required the attraction of a large number of qualified personnel.

In order to cope with the huge amount of work to maintain a growing vehicle fleet in technically sound condition, it is necessary to mechanize and automate the processes of vehicle maintenance and repair, and dramatically increase labor productivity.

Enterprises by maintenance and car repairs are equipped with more advanced equipment, new ones are introduced technological processes, ensuring a reduction in labor intensity and an increase in the quality of work.

Purpose and types of cooling system

The temperature of the gases in the combustion chamber at the moment of ignition of the mixture exceeds 2000°C. Such a temperature, in the absence of artificial cooling, would lead to strong heating of engine parts and their destruction. Therefore, air or liquid cooling of the engine is necessary. With air cooling, a radiator, water pump and pipelines are not required, and there is no danger of the engine “defrosting” in winter when filling the cooling system with water. Therefore, despite the increased power consumption for activating the fan and difficult starting at low temperatures, air cooling is used in passenger cars and a number of foreign cars.

The cooling system is a closed liquid type with forced circulation of liquid, with an expansion tank. Such a system is filled with water or antifreeze, which does not freeze at temperatures down to minus 40°C.

When the engine cools excessively, heat loss from the coolant increases, fuel does not completely evaporate and burns, which penetrates in liquid form into the oil pan and dilutes the oil. This leads to a decrease in engine power and efficiency and rapid wear of parts. When the engine overheats, decomposition and coking of the accelerating oil and carbon deposits occur, as a result of which heat dissipation deteriorates. Due to the expansion of parts, temperature gaps decrease, friction and wear of parts increase, and cylinder filling deteriorates. The coolant temperature when the engine is running should be 85-100°C.

Automotive engines use a forced (pump) liquid cooling system. Such a system includes cylinder cooling jackets, a radiator, a water pump, a fan, shutters, a thermostat, drain taps, and coolant temperature gauges.

The liquid circulating in the cooling system receives heat from the cylinder walls and their heads and transfers it through the radiator environment. Sometimes it is planned to direct the flow of circulating fluid through a water distribution pipe or a longitudinal channel with holes primarily to the most heated parts (convex valves, spark plugs, walls of the combustion chamber).

IN modern engines The engine cooling system is used to heat the intake manifold, cool the compressor, and heat the cabin or passenger area of ​​the body. Modern automobile engines use closed liquid cooling systems that communicate with the atmosphere through valves in the radiator cap. In such a system, the boiling point of water increases, water boils less often and evaporates less.

Design, composition and operation of the cooling system

The cooling system device includes: a fluid drain pipe from the heater radiator; pipe for discharging hot fluid from the cylinder head to the heater radiator; thermostat bypass hose; cooling jacket outlet pipe; radiator inlet hose; expansion tank; cooling jacket; radiator cap and tube; fan and its casing; pulley; radiator outlet hose; fan belt; coolant pump; coolant supply hose to the pump; and a thermostat.

The radiator is designed for cooling hot water coming out of the engine cooling jacket. It is located in front of the engine. A tubular radiator consists of upper and lower tanks connected to each other by three to four rows of brass tubes. Transverse horizontal plates add rigidity to the radiator and increase the cooling surface. The radiators of the ZMZ-53 and ZIL-130 engines are tubular-band with serpentine cooling plates (bands) located between the tubes. The cooling systems of these engines are closed, so the radiator caps have steam and air valves. The steam valve opens at an excess pressure of 0.45-0.55 kg/cm² (ZMZ-24, 53). When the valve opens, excess water or steam is discharged through the steam pipe. The air valve protects the radiator from compression by air pressure and opens when the water is cooled, when the pressure in the system decreases by 0.01-0.10 kg/cm².

If an expansion tank is installed in the cooling system, then the steam and air valves are located in the plug of this tank (ZIL-131).

To drain liquid from the cooling system, open the drain valves of the cylinder blocks and the drain valve of the radiator pipe or expansion tank.

For ZIL engines, the drain valves of the cylinder blocks and radiator pipes are remotely controlled. The valve handles are located in the engine compartment above the engine.

Slat-type blinds are designed to change the amount of air passing through the radiator. They are controlled by the driver using a cable and a handle brought into the cabin.

The water pump is used to circulate water in the cooling system. It consists of a housing, a shaft, an impeller and a self-sealing seal. The pump is usually located in the front part of the cylinder block and is driven by a V-belt from the engine crankshaft. The pulley simultaneously rotates the water pump impeller and the fan hub.

cooling system car repair

The self-sealing oil seal consists of a rubber seal, a graphitized textolite washer, a holder and a spring that presses the washer to the end of the supply pipe.

The fan is designed to increase the air flow passing through the radiator. The fan usually has 4-6 blades. To reduce noise, the blades are arranged in an X-shape, in pairs at an angle of 70 and 110°. The blade is made from sheet steel or plastic.

The blades have bent ends (ZMZ-53, ZIL-130), which improves the ventilation of the engine compartment and increases the performance of the fans. Sometimes the fan is placed in a casing, which increases the speed of air drawn through the radiator.

To reduce the power required to drive the fan and improve the performance of the cooling system, fans with an electromagnetic clutch (GAZ-24 Volga) are used. This clutch automatically turns off the fan when the water temperature in the upper radiator tank is below 78-85°C.

The thermostat automatically maintains a stable thermal regime for the engine. As a rule, they are installed at the coolant outlet from the cooling jackets of the cylinder heads or the engine intake pipe. Thermostats can be liquid or with solid filler.

The liquid thermostat contains a corrugated cylinder filled with an easily evaporating liquid. The lower end of the cylinder is fixed in the thermostat body, and a valve is soldered to the rod at the upper end.

When the coolant temperature is below 78°C, the thermostat valve is closed and all liquid is directed through the bypass hose back to the water pump, bypassing the radiator. As a result, overheating of the engine and intake manifold accelerates.

When the temperature exceeds 78°C, the pressure in the cylinder increases, it elongates and lifts the valve. Hot liquid is directed through a pipe and hose into the upper radiator tank. The valve opens completely at a temperature of 91°C (ZMZ-53). Thermostat with solid filler (ZIL-130) has a cylinder filled with ceresin and closed with a rubber diaphragm. At a temperature of 70-83°C, ceresin melts, expanding, moving the diaphragm, buffer and rod upward. This opens the valve and coolant begins to circulate through the radiator.

As the temperature decreases, ceresin hardens and decreases in volume. Under the action of the return spring, the valve closes and the diaphragm moves down.

In the engines of VAZ-2101 Zhiguli cars, the thermostat is made of a two-valve type and is installed in front of the water pump. When the engine is cold most of The coolant will circulate in a circle: water pump→cylinder block→cylinder head→thermostat→water pump. In parallel, the liquid circulates through the jackets of the intake pipe and the carburetor mixing chamber, and when the passenger room heater tap is open, through its radiator.

When the engine is not fully warmed up (fluid temperature below 90°C), both thermostat valves are partially open. Some of the liquid flows to the radiator.

When the engine is fully warmed up, the main flow of fluid from the cylinder head is directed to the radiator of the cooling system.

To monitor the coolant temperature, warning lights and indicators on the instrument panel are used. The instrumentation sensors are located in the cylinder heads, the upper radiator reservoir and the intake manifold cooling jacket.

Device Features

The coolant pump is a central type, driven by a V-belt from the crankshaft pulley. The fan has a four-bladed impeller, which is bolted to the pulley hub and is driven by the pump drive belt. The thermostat with a solid sensitive filler has a main and bypass valve. The opening of the main valve begins at a coolant temperature of 77-86°C, the stroke of the main valve is at least 6 mm. The radiator is vertical, tubular-plate, with two rows of tubes and tinned steel plates. The filler plug contains inlet and outlet valves.

Warning.

Checking the level and density of the liquid in the cooling system

The correct filling of the cooling system is checked by the fluid level in the expansion tank, which on a cold engine (at 15-20°C) should be 3-4 mm above the “MIN” mark marked on the expansion tank.

Warning. It is recommended to check the coolant level on a cold engine, because When heated, its volume increases and in a warm engine the fluid level can rise significantly.

If necessary, check the density of the coolant with a hydrometer, which should be 1.078-1.085 g/cm³. At low and high densities (more than 1.085-1.095 g/cm³), the temperature at which the liquid begins to crystallize increases, which can lead to its freezing in the cold season. If the liquid level in the tank is below normal, add distilled water. If the density is normal, add liquid of the same density and brand as is in the system. If below the norm, bring it up to it using TO-SOL-A liquid.

Filling the cooling system with liquid

Refueling is carried out when changing the coolant or after engine repair. Perform refueling operations in the following order:

1. Remove the plugs from the radiator and expansion tank and open the heater tap;

2. Pour coolant into the radiator, and then into the expansion tank, after installing the radiator cap. Close the expansion tank with a stopper;

3. Start the engine and let it run for Idling 1-2 minutes to remove air pockets. After the engine has cooled, check the coolant level. Jew. If the level is below normal and there are no signs of leakage in the cooling system, then add fluid.

Adjusting the pump drive belt tension

The belt tension is checked by deflection between the pump generator pulleys or between the pump and the crankshaft. With normal belt tension, deflection "A" under a force of 10 kgf (98N) should be within 10-15 mm, and the deflection " IN" within 12-17 mm. To increase the belt tension, loosen the generator mounting nuts, move it away from the engine and tighten the nuts.

Coolant pump

To disassemble the pump: — disconnect the pump body from the cover; — secure the cover in a vice using gaskets and remove the roller impeller using puller A.40026; — remove the fan pulley hub from the shaft using puller A.40005/1/5; — unscrew the locking screw and remove the bearing with the pump shaft; — remove the oil seal from the housing cover.

Check the axial clearance in the bearing (should not exceed 0.13 mm at a load of 49 N (5 kgf)), especially if significant pump noise is noted. Replace the bearing if necessary. It is recommended to replace the pump seal and the gasket between the pump and the cylinder block during repairs. Inspect the pump housing and cover; no deformations or cracks are allowed.

Assembling the pump: - install the oil seal using a mandrel, avoiding distortion, into the housing cover; — press the bearing with the roller into the cover so that the socket of the locking screw coincides with the hole in the cover of the pump housing; - tighten the bearing locking screw and caulk the contours of the socket so that the screw does not loosen; — using tool A.60430, press the pulley hub onto the shaft, keeping the size 84.4+0.1 mm. If the hub is made of metal ceramics, then after removal press on only a new one; — press the impeller onto the roller using device A.60430, which provides a technological gap between the impeller blades and the pump housing of 0.9-1.3 mm; — assemble the pump housing with the cover, install a gasket between them.

Thermostat

At the thermostat, you should check the opening temperature and the stroke of the main valve. To do this, install the thermostat on the BS-106-000 stand, lowering it into a tank of water or coolant. Jew. Press the indicator leg bracket against the main valve from below. The initial temperature of the liquid in the tank should be 73-75°C. The temperature of the liquid gradually increases by about 1°C/m with gradual coloring, so that it is the same throughout the entire volume of the liquid. The temperature at which the valve begins to open is taken to be the one at which the stroke of the main valve is 0.1 mm. The thermostat must be replaced if the temperature at which the main valve begins to open is not within 81+ 5\4 °C or the valve stroke is less than 6 mm. The simplest thermostat check can be done by touch directly on the car. After starting a cold engine with a working thermostat, the lower radiator tank should heat up when the liquid temperature gauge needle is approximately 3-4 mm from the red zone of the scale, which corresponds to 80-85 ° C.

Radiator

To remove the radiator from the car: - drain the liquid from it and the cylinder block, removing drain plugs in the lower radiator tank and on the cylinder block; At the same time, open the body heater valve and remove the radiator cap from the filler neck; — disconnect the hoses from the radiator; — remove the fan casing; — Unscrew the bolts securing the radiator to the body, remove the radiator from the engine compartment.

The tightness is checked in a bath of water. Having plugged the radiator pipes, supply air to it at a pressure of 0.1 MPa (1 kgf/cm²) and lower it into a bath of water for at least 30 s. In this case, there should be no etching of air. Slightly damaged brass radiator solder soft solder, and if significant, replace with a new one.

Cooling system repair

Main possible defects in water pump parts: chips and cracks in the housing, thread failure in the holes, wear of the bearing seats and thrust bushing; bending and wear of the impeller seat on the shaft, under bushings, seals and fan pulleys; wear, cracks and corrosion of the surface of the impeller blades; wear on the inner surface of the bushings and keyway. The cooling pump housing is made from ZIL-130 aluminum alloy AL4, the bearing housing is made from gray cast iron; for ZMZ-53 - from SCh 18-36, for YaMZ KamAZ - from SCh 15-32. The main defects of the bearing housing of the water pump of the ZIL-130 engine: wear of the end surface under the thrust washer; broken ends of the socket and wear of the hole for the rear bearing; and wear of the hole for the front bearing.

Cracks and breaks in the body are welded or sealed with synthetic materials. Chips on the flange and cracks on the body are repaired by welding. The part is preheated. It is recommended to weld with an acetylene-oxygen neutral flame. Cracks can be sealed with epoxy resin. Worn bearing surfaces with gaps of no more than 0.25 mm should be restored with Unigerm-7 and Unigerm-11 sealants. If the gap is more than 0.25 mm, thin (up to 0.07 mm thick) steel strips must be installed to eliminate the defect.

A bent roller is straightened under a press, and a worn-out roller that is less than acceptable is restored by chrome plating and subsequent grinding to the nominal size. The worn keyway on the shaft is welded, and then a new groove is milled at an angle of 90-180° to the old one.

Impellers can be made by casting from aluminum alloy or nylon. In this case, the hub (bushing) must be steel.

After restoration, the cooling pump housing must meet the following technical requirements: end runout of the surface of the bearing housing under the impeller thrust washer relative to the axis of the holes for the bearings is no more than 0.050 mm; runout of the end surface of the bearing housing flange under the pump housing relative to the bearing holes is no more than 0.15 mm; the roughness of the surface of the bearing housing for the impeller thrust washer is no more than Ra = 0.80 µm, the surface roughness of the holes for the bearings is no more than Ra = 1.25 µm.

Cooling pump rollers are made by ZIL and ZMZ from steel 45, HRC 50-60; at YaMZ - from steel 35, HB 241-286; KamAZ has steel 45X, HRC 24-30. The main defects of the roller: wear of the surface under the bearings; wear of the journal under the impeller; groove wear; thread damage.

Worn surfaces are restored by surfacing in a carbon dioxide environment, followed by chrome plating or iron plating, followed by grinding on a centerless grinding machine. On the sealing washer, risks and wear to a depth of no more than 0.5 mm are allowed. If there is more wear, the washer is replaced. When installing the roller, 100 g of Litol-24 lubricant should be placed in the inter-bearing cavity. Before installation, the sealing washer and the end of the support sleeve should be coated with a thin layer of sealant or lubricant consisting of 60% by weight diesel oil and 40% graphite.

Worn or damaged threads in holes are restored by cutting a thread of a repair size or by welding followed by cutting a thread of a nominal size.

After assembly, the gap between the water pump body and the impeller blades should be 0.1...1.5 mm and the roller should rotate easily.

Water pumps are run in and tested on special stands, for example, pumps for the YaMZ-240B engines - on the OR-8899 stand, for the D-50 and D-240 engines - on the KI-1803, for the ZMZ-53 engine - on the OR-9822. Run-in is performed for 3 minutes at a water temperature of 85...90°C and tested according to the regime.

Each repaired pump is tested for leaks at a pressure of 0.12...0.15 MPa. Water leakage through seals and stud threads is not allowed.

Possible defects in fan parts the following: wear of the seats in the pulleys for the outer rings of the rolling bearings, wear of the grooves in the pulleys for the belt, loosening of the rivets on the crosspiece, bending of the crosspiece and blades.

Worn out seats bearings are restored by iron plating and chrome plating. Worn pulley grooves (up to 1mm) are sharpened. Loose rivets on the blade crosspiece are tightened. If the holes for the rivets are worn out, they are drilled out and rivets of increased diameter are installed. The leading edges of the blades after riveting must lie in the same plane with a deviation of no more than 2 mm. A template is used to check the shape of the fan blades and their angle of inclination relative to the plane of rotation, which should be within 30...35° (adjust if necessary).

The fan assembled with a pulley is statically balanced. To eliminate the imbalance, unbalance recesses are drilled, recesses are drilled in the end of the pulleys, or the blade is made heavier on its convex side by welding or riveting a plate.

If in drive fluid coupling the fan is leaking oil through the seals, there is axial play and jamming of the driven and drive shafts when the impeller blades and pulley rotate by hand, repairs are required.

There are defects in the fluid coupling parts similar to defects in fan parts. This determines similar ways to eliminate them. Fluid coupling ball bearings must be replaced when the axial and radial clearance exceeds 0.1 mm.

During assembly, the gap between the driven and driven wheels of the fluid coupling should be 1.5...2 mm. The fluid coupling drive pulley with the fan hub stationary and, conversely, the hub with the pulley stationary must rotate freely. The thermal power sensor of the fluid coupling switch is adjusted by setting the adjusting washers to turn on at a coolant temperature of 90...95°C and turn off at a temperature of 75...80°C.

Cooling system radiators made of: upper and lower tanks and tubes - brass, cooling plates - copper, frame and brass; Oil radiator tanks are steel.

Radiators can have the following basic defects: scale deposits on the inner walls of tubes and tanks, their damage and contamination of the outer surfaces of tubes, cores, cooling plates and frame plates, tube leaks, holes, dents or cracks in tanks, leakage in solder areas. After removal from the car, the radiator goes to the repair site, where it is washed from the outside and checked for defects by external inspection and leak testing compressed air under a pressure of 0.15 MPa for oil radiators in a bath of water at a temperature of 30...50°C. During testing, sealed with rubber plugs, the water radiator is filled with water and created by a pump overpressure: within 3...5 minutes the radiator should not leak. If leaks are detected, the radiator is disassembled, the core is placed in a bath of water and, by supplying air through a hose from a hand pump into each tube, the location of the damage is determined by the bubbles. Pollution and scale are removed in installations that provide heating of the solution to 60-80°C, its circulation and subsequent flushing of the radiator with water. The holes are closed with rubber plugs, through one of which it flows through a hose to check for defects. When radiators are repaired without disassembling (without removing the barrels), a leak test is carried out after descaling.

Tube leaks are eliminated by soldering. Damaged tubes located in the inner rows are sealed (plugged) at both ends. It is allowed to seal up to 5% of the tubes; if the number is larger, the damaged tubes are replaced. Replace with new plugged tubes and tubes with large dents. To do this, hot air is blown through the tubes, heated to 500-600°C in a coil mounted on a blowtorch. When the solder melts, the tube is removed with special pliers with a tongue with dimensions and shape corresponding to the cross-section of the tube hole. The tubes can be soldered using a cleaning rod heated to 700-800°C in a forge, or passed through it electricity from a welding transformer. The old tubes are removed and new or repaired ones are inserted in the direction of the antennae of the cooling plates. The tubes are soldered to the support plates with solder.

According to another technology, the defective tube is flared to a large diameter (use a square ramrod for round tubes or a knife-shaped one with a widening at the end for flat ones) and a new one is inserted, soldering it at the ends to the support plates.

The total number of newly installed or lined pipes for diesel engines should not be more than 20% of their total number, and for carburetor engines — 25%.

At major damage after soldering the support plates, cut out the defective part of the radiator (use band saws and instead install the same part of the radiator from another rejected one, soldering all the tubes to the support plates.

Cracks in cast iron tanks are repaired by welding. In brass tanks, cracks and breaks are repaired by soldering.

Dents in tanks are removed by straightening, for which the tank is placed on a wooden block and the damage is smoothed out with a wooden hammer. Holes are eliminated by installing patches from sheet brass and then soldering them. The cracks are sealed.

Damage to the frame plates is repaired by gas welding. The dented radiator plates are straightened using a comb.

The repaired radiator is checked in a bathtub, having first pumped air into it.

Repair operations for oil radiators are similar to those for repairing water radiators. Resinous reflections in them are removed in the preparation AM-15. Soldering of tubes to tanks is carried out using copper-zinc PMC solder using gas welding. Oil radiators are tested under a pressure of 0.3 MPa.

When repairing thermostats- remove scale. Damage to the spring box area is sealed with POS-40 solder. Spring boxes are filled with a 15% solution of ethyl alcohol.

When testing the thermostat in a bath of water, the start of valve opening should be 70°C, and full opening should be at 85°C. The height of the full valve lift is 9-9.5 mm. It is adjusted by rotating the valve on the threaded end of the spring box shank.

Conclusion

Diagnostic methods using electronic equipment are increasingly being introduced into vehicle maintenance. Diagnostics allows you to promptly identify faults in vehicle units and systems and eliminate them before they cause serious problems. Objective assessment methods technical condition units and components of the car help in time to eliminate defects that can cause emergency situation, which improves road safety.

The use of modern equipment to carry out maintenance and repair work on cars facilitates and speeds up many production processes, but requires service personnel to acquire a certain range of knowledge and skills: the structure of the car, the basic technological processes of maintenance and repair, the ability to use modern instrumentation and tools and devices.

To study the structure and operating processes of car mechanisms, knowledge of physics, chemistry, and basic electrical engineering is required in the scope of secondary school programs.

The use of modern equipment and devices for performing installation and dismantling work of car repairs does not exclude the need to master the skills of general metalwork that a worker engaged in repairs must possess.

Well-organized maintenance, timely elimination of malfunctions in vehicle units and systems, with highly qualified work performed, can increase the durability of vehicles, reduce their downtime, increase the time between repairs, which ultimately significantly reduces overhead costs and increases the profitability of operating vehicles.

(ICE) and their components are subject to intense heat during operation of various vehicles. At the same time, both overheating and hypothermia of the motor can provoke its failure. In this regard, one of the most important tasks of power unit developers is to ensure optimal thermal conditions for their operation. A well-organized engine cooling system helps to obtain the best operational parameters of the internal combustion engine, which include:

1. Maximum power.
2. Minimum fuel consumption.
3. Extended service life.

The influence of temperature parameters on motor operation

During one working cycle, the temperature in the internal combustion engine cylinders varies from 80...120 degrees Celsius during intake combustible mixture up to 2000...2200 degrees Celsius during its combustion. In this case, the power unit gets quite hot.

If the motor is not cooled intensively enough during operation, its parts become very hot and change in size. The volume of engine oil poured into the crankcase also decreases significantly (due to burnout). As a result, friction between interacting parts increases, which leads to their rapid wear or even jamming.

However, overcooling of the internal combustion engine also negatively affects its operation. Condensation of fuel vapor occurs on the cylinder walls of a cold engine, which, washing away the lubricant layer, dilutes the engine oil in the crankcase.

To eliminate the negative consequences associated with violation of the thermal regime, cooling systems are designed to prevent overheating and overcooling of the motor during operation.

As a result Chemical properties the latter worsen, which contributes to:

• increased engine oil consumption;
• intensive wear of rubbing surfaces;
• drop in power of the power unit;
• increased fuel consumption.

Classification

When the motor is running, it is necessary to ensure that 25 to 35% of the generated heat is removed. For its effective absorption (removal), water, air or special liquid(antifreeze, antifreeze). The coolant material determines the cooling method of the power unit.

There are systems:

1. Forced air cooling.
2. Closed cycle liquid cooling.

Liquid cooling system

Currently for efficient cooling car engines use closed system Closed cycle liquid cooling.

Design

IN mandatory the system contains an expansion tank, which serves to compensate for changes in the volume of liquid when its temperature changes. In addition, coolant is poured through it.

The system also includes:

• water jacket of the power unit (the space between the double walls of the cylinder block and its head in places where excessive heat is removed);
• temperature sensor;
• bimetallic or electronic thermostat that ensures the optimal temperature in the system;
• a centrifugal pump that provides forced circulation of coolant in the system;
• a fan, which increases the flow of oncoming air to the main radiator of the system;
• a radiator that transfers heat to the environment;
• heater radiator, designed to transfer heat directly to the vehicle interior;
• a control device built into the dashboard of a car.

Operating principle

Coolant is poured into the system through the expansion tank. Constantly circulating inside the system, it removes heat from components The engine, which heats up during operation, heats up, enters the radiator, is cooled in the radiator by a counter flow of air and returns back.

If necessary, the fan turns on, enhancing cooling efficiency. For closed cooling systems, the coolant temperature should not exceed 126 degrees Celsius. This ensures optimal thermal operation of the power unit.

Additional functions

In addition to its main task - removing heat from heating elements, the liquid engine cooling system also provides:

• Warming up the power unit in the cold season

IN modern systems Liquid cooling has two circuits through which coolant can circulate. This is done so that at the moment of starting a cold engine, when its parts and the liquid itself are at a low temperature, the coolant circulates in a small circle (past the radiator).

This is ensured by a thermostat, which, when the temperature rises to a certain level (70-80 degrees Celsius), opens, allowing the coolant to circulate in a large circle (through the radiator). Thus, the engine warms up process is accelerated.

• Heating the air inside the car

During the cold season, hot coolant is used to heat the air in the car interior. For this purpose, there is an additional radiator installed in the cabin and equipped with its own fan. With their help, the heat taken from the hot liquid is distributed throughout the entire volume of the cabin.

• Reducing the temperature of the air forced into the cylinders

Especially for engines equipped with turbochargers, dual-circuit systems are provided, in which one circuit provides liquid cooling, and the second provides air cooling.

In addition, the coolant cooling circuit is also dual circuit system, one circuit of which cools the cylinder head, and the other cools the block itself.

This is due to the fact that in a turbocharged engine the temperature of the cylinder head should be 15...20 degrees Celsius lower than the temperature of the block itself. A special feature of this cooling system is that each circuit is controlled by its own thermostat.

Advantages and disadvantages

Almost everyone has a liquid engine cooling system. modern cars. Fundamentally different from air cooling systems, it guarantees:

• uniform and rapid heating of the power unit;
• effective heat removal under any engine operating conditions;
• reduction of power costs;
• stable thermal operating conditions of the motor;
• the possibility of using the generated heat to heat the air in the cabin, etc.

Among the few disadvantages of a liquid cooling system are:

• the need for regular maintenance and the complexity of repairs;
• increased sensitivity to temperature changes.

Malfunctions and ways to eliminate them

All liquid cooling systems have characteristic malfunctions. The most common:

1. the thermostat is stuck in the closed position (liquid circulation is carried out in a small circle);
2. pump breakdown;
3. damage to the exhaust valve built into the expansion tank plug;
4. leakage of coolant due to depressurization of the system (damage to seals, corrosion, etc.).
5. In addition, quite often the thermostat gets stuck in the “Open” position (the coolant circulates in a large circle), which increases the warm-up time of a cold engine and contributes to instability of the thermal regime during its further operation.

All these malfunctions are characterized by a significant increase in the operating temperature of the power unit, which can lead to boiling of the coolant and overheating of the engine.

All defects are eliminated by replacing faulty and/or damaged parts or components.

Air cooling system

Vehicles were equipped with air-cooled motors in the 50-70s of the last century. Typical representatives of such cars are the Zaporozhets or FIAT 500. Nowadays, air-cooled engines are practically never found in the automotive industry.

Design and principle of operation

Structurally, the forced air cooling system is mounted in the engine compartment of the vehicle and consists of:

• suction or forcing fan;
• guide fins of the engine cooling jacket;
• governing bodies ( throttle valves, controlling the air supply or a clutch that regulates the fan speed in automatic mode);
• temperature sensor installed in the power unit;
• control device displayed on dashboard inside the car.

The motor is cooled by counter cold air. To enhance its flow, a forced-type fan is most often used. It enhances the flow of cold dense air and provides it in large quantities at low energy costs.

The suction fan requires more power, but provides more uniform heat removal from the parts of the power unit.

Advantages and disadvantages

Motors with forced air cooling differ:

• simplicity of design;
• low requirements for changes in ambient temperature;
• light weight;
• easy maintenance.

The disadvantages of an air cooling system include:

• a large loss of motor power, which is spent to ensure the operation of the fan;
• high noise level during fan operation;
• insufficient cooling of individual engine elements due to uneven airflow;
• inability to use excess heat to heat the interior.