Home Brakes The principle of the cooling system. How the cooling system works How the coolant circulates

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The principle of the cooling system. How the cooling system works How the coolant circulates

A cooling system is required to maintain the engine's optimum temperature.

The average engine temperature is 800 - 900 ° C, with active work it reaches 2000 ° C. But periodically it is necessary to remove heat from the engine. Failure to do so could cause the engine to overheat.

But the cooling system not only cools the engine, but also participates in heating it when it is cold.

Most cars have a closed-type liquid cooling system with forced circulation of liquid and an expansion tank (Figure 7.1). Rice. 7.1. Diagram of the engine cooling system a) small circle of circulation b) large circle of circulation 1 - radiator; 2 - branch pipe for circulation of coolant; 3 - expansion tank; 4 - thermostat; 5 - water pump; 6 - cylinder block cooling jacket; 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

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

Under the guidance of the thermostat, 2 circulation circles perform their functions (Figure 7.1). The small circle performs the function of heating the engine. After heating, the liquid begins to circulate in a large circle and is cooled in the radiator. Normal coolant temperature is 80-90 ° C.

The engine cooling jacket is the channels in the block and the cylinder head. Coolant circulates through these channels.

A centrifugal pump assists in moving fluid around the jacket and throughout the engine system. forces fluid to move through the engine cooling jacket and the entire system.

The thermostat is a mechanism that maintains optimal thermal conditions of the engine. When a cold engine is started, the thermostat is closed and the fluid flows in a small circle. When the temperature of the liquid exceeds 80-85 ° C, the thermostat opens, the liquid begins to circulate in a large circle, getting into the radiator and cooling.

The radiator consists of many tubes that form a large cooling surface. This is where the liquid is cooled.

Expansion tank. With its help, the volume of the liquid is compensated when it is heated and cooled. The fan increases the air flow to the radiator, with the help of which the

liquid is waiting.

The pipes and hoses are the connection mechanism of the cooling jacket with the thermostat, pump, radiator and expansion tank.

The main malfunctions of the cooling system.

Coolant leaks. Cause: Damage to the radiator, hoses, gaskets and oil seals. Remedies: tighten the hose and pipe clamps, replace damaged parts with new ones.

Overheating of the engine. Reason: insufficient coolant level, weak fan belt tension, clogged radiator pipes, thermostat malfunction. Remedies: restore the fluid level in the cooling system, adjust the fan belt tension, flush the radiator, replace the thermostat.

For this, the cars have an engine cooling system. The centrifugal pump forces the fluid to move through the engine cooling jacket and the entire system. Cooling system operation. The engine cooling jacket is the channels in the block and the cylinder head.

Thermostat 7. Regulates the circulation in a small or large circle depending on the temperature. The circulation through the stove is constant, regardless of what position the thermostat is in, and in which circle the liquid circulates.

The pressure in the system is needed in order to raise the boiling point. Even when the temperature reaches 110 degrees, the liquid in the system does not boil. We started the cold engine. Immediately, we have a circulation of coolant in the system. The circulation of fluid is created by pump 6 (Fig. 1), driven by a timing belt or a separate belt.

The liquid will circulate in the following pattern until it reaches a certain temperature. Then the thermostat 7 will close the small circle and open the large one. The cooled liquid is pumped back into the engine by the pump. If the free cooling of the liquid in the radiator is not enough and the coolant temperature continues to rise, then the fan switch 4 located at the bottom of the radiator is triggered.

At this temperature, optimal thermal clearances are established in the engine, the engine develops maximum power, and the fuel consumption becomes nominal. Under the guidance of the thermostat, 2 circulation circles perform their functions (Figure 7.1). The small circle performs the function of heating the engine. After heating, the liquid begins to circulate in a large circle and is cooled in the radiator.

Coolant circulates through these channels. The radiator consists of many tubes that form a large cooling surface. This is where the liquid is cooled. Expansion tank. With its help, the volume of the liquid is compensated when it is heated and cooled.

The next time you can start your cold engine only after a major 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. In figure 25, you can easily distinguish between the two circles of coolant circulation.

Engine cooling system diagram.

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. To monitor the operation of the system, there is a coolant temperature indicator on the instrument panel. The pump is driven by a belt drive from the engine crankshaft pulley. When starting a cold engine, the thermostat is closed, and all the liquid circulates only in a small circle (Fig. 25) to warm it up as soon as possible.

At high temperatures, the thermostat opens completely and already all the hot liquid is directed along a large circle for its active cooling. The 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.

Cooling systems of various designs

An expansion tank is necessary to compensate for changes in the volume and pressure of the coolant when it is heated and cooled. The pipes and hoses are used to connect the engine cooling jacket to the thermostat, pump, radiator and expansion tank. The hot coolant flows through the heater radiator and heats the air into 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.

In other words, you need to put in order the cooling system of your engine. 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. And this is the second part of the cooling system. The thermostat is designed to maintain a constant optimal thermal condition of the engine. Maintains a certain pressure in the cooling system.

Let us recall a little more about this cooling system.

V 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 prevent the formation of scale. They are highly poisonous and must be handled with care. 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 may overheat the engine in summer.

The optimal temperature regime of the engine with a liquid cooling system is considered to be one at which 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. The coolant 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 from:

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 car's interior.

How the cooling system works

I propose to first consider the schematic diagram of the cooling system.

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 circle of circulation (thermostat is 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- 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.

Look for our liquid pump or water pump 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 - an epiploon; 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 sensing 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 withengine cooling jacket,

Across branch pipe 11- with bottom diverting radiator reservoir.

The sensitive element of the thermostat consists of a balloon 4, a rubber diaphragm 5 and a stem 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 comes out of 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 visually 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, connected to each other. Now let's move on to the large circle and the key element of the large circle - the radiator.

3. Radiator (radiator / cooler)

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

So, there are 2 types of radiators: collapsible and not 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 motor shaft. The blades on the fan hub are located unevenly and at an angle to the plane of its 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 temperature of the coolant.

So let's summarize. Let's 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 the 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 the liquid cannot flow through the thermostat bypass pipe (3) and is forced to flow through the inlet pipe (5) into the radiator (9). There, the liquid is cooled and flows back to the liquid pump (16) through the thermostat (18).

It is worth noting that some of the coolant flows from the engine cooling jacket to the heater 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 become clear to you. After reading this article, I hope it will be possible to navigate in another cooling system, having understood the principle of operation of this one.

I also propose to read the following article:

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

When the human circulatory system is divided into two circuits of blood circulation, the heart is exposed to less stress than if the body had a common blood supply system. In the pulmonary circulation, blood travels to the lungs and then back thanks to a closed arterial and venous system that connects the heart and lungs. Its path begins in the right ventricle and ends in the left atrium. In the pulmonary circulation, blood with carbon dioxide is carried by arteries, and blood with oxygen is carried by veins.

From the right atrium, blood enters the right ventricle and is then pumped into the lungs through the pulmonary artery. From the right venous blood enters the arteries and lungs, where it gets rid of carbon dioxide, and then is saturated with oxygen. Through the pulmonary veins, blood flows into the atrium, then it enters the systemic circulation and then goes to all organs. Since it is slowly in the capillaries, carbon dioxide has time to enter it, and oxygen has time to penetrate the cells. Because blood enters the lungs at low pressure, the pulmonary circulation is also called a low pressure system. The time for blood to pass through the pulmonary circulation is 4-5 seconds.

With an increased demand for oxygen, for example, with intense sports, the pressure generated by the heart increases and the blood flow accelerates.

A large circle of blood circulation

The systemic circulation begins from the left ventricle of the heart. Oxygenated blood flows from the lungs into the left atrium and then into the left ventricle. From there, arterial blood enters the arteries and capillaries. Through the walls of the capillaries, the blood transfers oxygen and nutrients into the tissue fluid, taking carbon dioxide and metabolic products. From the capillaries, it enters the small veins that form larger veins. Then, through two venous trunks (superior vena cava and inferior vena cava), it enters the right atrium, ending the systemic circulation. The blood circulation in the systemic circulation is 23-27 seconds.

Blood flows through the superior vena cava from the upper parts of the body, and along the lower - from the lower parts.

The heart has two pairs of valves. One of them is located between the ventricles and the atria. The second pair is located between the ventricles and arteries. These valves provide direction for blood flow and interfere with the return flow of blood. Blood is pumped into the lungs under great pressure, and it enters the left atrium under negative pressure. The human heart has an asymmetrical shape: since its left half does more heavy work, it is somewhat thicker than the right.

I propose to first consider the schematic diagram of the cooling system.

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 - a large circle of circulation (the thermostat is 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- 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.

So, the beginning of the operation of the cooling system occurs when the heart of this system - the liquid pump - starts up.

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.

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

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

1 - pump cover; 2 - The persistent sealing ring of the stuffing box.
3 - an epiploon; 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.

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

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.

Thermostat

This unit looks like this in reality:

Thermostat device:

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

Compound:

Acrossbranch pipe 1 connects withengine cooling jacket,

Across branch pipe 11- with bottom diverting radiator reservoir.

The operation of the valve is clearly and visually 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.

Radiator (radiator / cooler)

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

So, there are 2 types of radiators: collapsible and not 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.

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 its 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 temperature of the coolant.

It is worth noting that some of the coolant flows from the engine cooling jacket to the heater through pipe 2 and returns from the heater through pipe 1.