Engine work internal combustion (DVS) leads to excessive heating of all its parts and without cooling them functioning the main unit vehicle It is impossible. This role is performed by the engine cooling system, which is also responsible for heating the auto cabin. In turbocharged engines, it is reduced by the air temperature reached into the cylinders, and this system cools the liquid in the automatic transmission, which is used for its operation. Separate models of cars are equipped with an oil radiator, which takes part in the thermorellation of oil used to lubricate the engine.
The cooling system of the engine is air and liquid
Both of these systems are not perfect and have both advantages and disadvantages.
Advantages of the cooling air system:
- low weight of the engine;
- easy device and its maintenance;
- low demanding to temperature changes.
Disadvantages of the cooling air system:
- big noise from engine operation;
- overheating of individual parts of the motor;
- the inability to build cylinders blocks;
- difficult to use heat released to heal the car's cabin.
In modern conditions, automakers prefer to equip their cars mainly by engines with liquid cooling systems. Air structures, cooling motors, are very rare.
Advantages of the liquid cooling system:
- not such a noisy engine compared to the air system;
- high speed of starting work when starting the motor;
- uniform cooling of all parts of the power mechanism;
- less predisposition to detonation.
Disadvantages of the liquid cooling system:
- expensive maintenance and repair;
- possible leakage of fluid;
- frequent motor hyposals;
- freezing of the system in periods of frost.
Structure of the Liquid Engine Cooling System
To the main component of the liquid system cooling in DVS The following details are:
- "Water shirt" engine
- fan;
- radiator;
- pOMP (centrifugal pump);
- thermostat;
- expansion tank;
- heat exchanger heater;
- components of controls.
Water shirt of the engine is the plane between the walls of the unit in those places that require cooling.
The radiator of the cooling system is a mechanism that is intended for the recoil created by the work of the heat engine. The node is a construction of many curved aluminum pipes, which also have additional edges that contribute to greater heat transfer.
The fan is used to accelerate air circulation, enveloping the radiator. The fan turns on under the boundary heating of the coolant.
The centrifugal pump (in other words - pump) provides uninterrupted fluid movement during engine operation. The pump drive may be different: belt, for example, or gear. On a car with turbocked engines, additional pumps are often installed, which contribute to the circulation of the liquid and run from the control unit.
The thermostat is a device in the form of a bimetallic (or electronic) valve located between the inlet of the radiator and the "cooling jacket". This device provides the desired fluid temperature that serves to cool the engine. When the motor cooled, the thermostat is closed, therefore, forced circulation of the cooling fluid passes inside the engine without affecting the radiator. At the time of heating the liquid to the boundary temperature, the valve opens. At this point, the system begins to function in all its power.
The expansion tank is used to inflate the coolant. This node compensates for the change in the amount of fluid in the system during temperature change.
The heater radiator is a mechanism intended for air heating in the vehicle cabin. His working fluid Visits directly near the entrance to the "shirt" of the motor.
The main element of coordination of the cooling system of the engine is a sensor (temperature), the electronic unit Management, as well as executive devices.
Engine cooling system
The cooling system operates under the control of the power unit control system. The pump launches the circulation of fluid in the "engine cooling shirt". Considering the degree of heating, the fluid moves either by small or by big circle.
In order for the engine faster after launch, the liquid circulates in a small circle. After it is heated, the thermostat opens, providing liquids the ability to circulate through the radiator, at the exit from which the air flow (oncoming or from the operating fan) is affected by the fluid, which cools it.
A double-circuit cooling system can be used in turbocharging motors. A feature of her work is that one contour controls the cooling of the injected air, and the second is cooling the engine.
The cooling system is designed to cool the engine parts heated as a result of its operation. On the modern carsmobile The cooling system, in addition to the main function, performs a number of other functions, including:
Depending on the cooling method, the following types of cooling systems are distinguished: liquid (closed), air (open) and combined. In the liquid cooling system, the heat from the heated parts of the engine is given by the flow of fluid. Air system for cooling uses air flow. The combined system combines the liquid and air system.
A liquid cooling system was obtained on cars the greatest distribution. This system provides uniform and effective coolingAnd also has a smaller noise level. Therefore, the device and principle of the cooling system are considered on the example of a liquid cooling system.
The design of the cooling system of gasoline and diesel engines Like. The engine cooling system includes a plurality of elements, among which the coolant radiator, oil radiator, heater heat exchanger, radiator fan, centrifugal pump, and an expansion tank and thermostat. In the cooling system circuit, the engine cooling shirt is enabled. To regulate the system operation, controls are used.
The radiator is designed to cool the heated coolant air flow. To increase the heat transfer, the radiator has a special tubular device.
Along with the main radiator in the cooling system, an oil radiator and the radiator of the exhaust gas recirculation system can be installed. Oil radiator serves to cool oil in the lubrication system.
The radiator of the exhaust gas recirculation system cools the exhaust gases than the decrease in the combustion temperature of the fuel-air mixture and the formation of nitrogen oxides. The operation of the exhaust gas radiator provides an additional coolant circulation pump included in the cooling system.
The heat exchanger of the heater performs the function opposite to the cooling system radiator. The heat exchanger heats through it, air. For efficient operation, the heater heat exchanger is installed directly at the output of the heated coolant from the engine.
To compensate for changes in the volume of coolant due to temperature in the system, an expansion tank is installed. Filling the coolant system is usually carried out through the expansion tank.
Circulation of coolant in the system is provided by a centrifugal pump. In everyday life, the centrifugal pump is called pompey. The centrifugal pump can have a different drive: gear, belt, etc. On some engines equipped with turbocharged, for cooling upward air and the turbocharger, an additional coolant circulation pump connected by the engine control unit is installed.
The thermostat is designed to adjust the amount of coolant passing through the radiator than the optimal temperature mode in the system is ensured. The thermostat is installed in the nozzle between the radiator and the "engine cooling shirt".
On the powerful engines An electrical heating thermostat is installed, which provides two-stage coolant temperature control. For this, there are three working provisions in the design of the thermostat: closed, partially open and fully open. With the full load on the engine with electric heating The thermostat is made full opening. In this case, the temperature of the coolant decreases to 90 ° C, the engine's tendency to detonation decreases. In other cases, the coolant temperature is maintained within 105 ° C.
The radiator fan is used to increase the intensity of the cooling of the liquid in the radiator. The fan can have a different drive:
- mechanical ( permanent connection S. crankshaft Engine);
- electric ( controlled electric motor);
- hydraulic ( hydromefta).
The highest distribution was obtained by an electric drive of the fan, providing ample opportunities for regulation.
Type elements of the cooling system controls are the coolant temperature sensor, an electronic control unit and various actuators.
The coolant temperature sensor captures the value of the controlled parameter and converts it to an electrical signal. To expand the functions of the cooling system (cooling of the exhaust gases in the exhaust gas recirculation system, the operation of the fan, etc.) at the radiator output, an additional cooling fluid temperature sensor is set.
Signals from the sensor receives an electronic control unit and converts them to control exposure to actuators. Used, as a rule, the engine control unit with set by the appropriate software.
The following actuators can be used in the management system: thermostat heater, relay additional pump Coolant, radiator fan control unit, engine cooling relay after stopping.
Principle of operation of the cooling system
The cooling system provides the engine control system. IN modern engines The work algorithm is implemented on the basis of mathematical modelwhich takes into account the various parameters (coolant temperature, oil temperature, outer temperature, etc.) and sets optimal conditions for the inclusion and operation time of structural elements.
The coolant in the system has a forced circulation, which the centrifugal pump provides. The movement of the fluid is carried out through the "shirt of the cooling" engine. In this case, the engine cooling and the heating of the coolant. The direction of fluid movement in the "cooling shirt" can be longitudinal (from the first cylinder to the last) or transverse (from the exhaust manifold to the inlet).
Depending on the temperature, the liquid circulates in a small or large circle. When the engine is started, the engine itself and the cooling fluid in it is cold. To accelerate the engine warming, the coolant moves along a small circle, bypassing the radiator. The thermostat is closed.
As the coolant is heated, the thermostat opens, and the coolant moves along a large circle - through the radiator. The heated fluid passes through the radiator, where it is cooled by the opposite stream of air. If necessary, the liquid is cooled by the flow of air from the fan.
After cooling, the liquid arrives at the engine cooling shirt. During the operation of the engine, the cycle of the coolant movement is repeated multiple times.
A double-circuit cooling system can be used on turbocharging cars, in which one contour is responsible for cooling the engine, the other for cooling the adequate air.
The cooling system is designed to remove heat from the mechanisms and parts of the engine, as well as to maintain normal thermal regime Engine.
Liquid systems with automotive engines received the most distribution with forced circulation Coolant.
Such systems are more efficient in operation and together with starting devices provide easy engine start at negative ambient air temperatures and create less noise when it works (Fig. 1).
The cooling system consists of:
shirts cooling the block and head of the cylinder block;
centrifugal pump;
thermostat 4;
radiator with expansion tank 1;
fan 3;
connecting nozzles and hoses.
The cooling system is filled with liquid through the expansion tank 6 (Fig. 3) or the neck of the radiator.
In the radiator lid or the tank, a steam valve is made, which supports increased pressure in the cooling system during engine operation, thereby increasing the temperature of the toosol.
Fig.1.
1 - radiator; 14 - piston; 2 - lid; 15 - drain crane; 3 - fan; 16 - lower radiator tank; 4 - thermostat; 5 - liquid pump; 6 - expansion tank; 7 - cylinder head; 8 - pipeline to heater; 9 - fluid temperature pointer; 10 - heater fan; 11 - heater radiator; 12 - shirt Cooling Cylinder Head; 13 - Shirt Cooling Cylinder Block.
As the engine stopped is cooling, the valve gradually reduces the pressure, preventing the radiator gap and expansion tank. To drain the liquid, the holes are opened at the bottom of the radiator and the cylinder block, closed with threaded plugs or taps15.
During the engine operation, the liquid circulates in the engine cooling system under the action of a centrifugal liquid pump of 15 coolant liquid. The fluid flow distribution controls the thermostat.
While the engine does not warm, the liquid circulates in a small circle. In fact, within the shirt cooling the head and block of cylinders. As the engine is heated, the thermostat valve opens, and part of the fluid, and then its entire flow is directed to the radiator (large circulation circulation), where it is cooled by the flux of the incident air and the fan.
The impeller of the fan on some engines is driven by the belt transmission from the crankshaft pulley. A more modern design is an electric cooling system fan, which runs from the cargo power grid and controlled by a thermal sensor installed in the radiator tank.
The engine cooling system is constructively combined with the car heating system of the car's passenger compartment. The heated liquid enters the heater radiator8 from the cylinder head cooling shirt on the upper pipeline, and the coolant pump is discharged along the lower pipeline.
The fluid flow through the heater radiator is adjustable or overlaps with a heater with a heater, managed from the driver's seat.
Workflows car Engine Pass at high temperatures, so to ensure its performance for a long time it is necessary to remove the height heat. This feature provides a cooling system (CO). In the cold season, heating the cabin is made at the expense of this heat.
In the car used turbocharged, the function of the cooling system includes a decrease in air temperature supplied to the combustion chamber. Additionally, one of the circles from the cooling system of some models of cars, equipped with automatic box Transmissions (automatic transmission), the cooling of oil in the automatic transmission is turned on.
There are two main types of CO: Water and Air. The principle of operation of the cooling engine of water cooling is to heat the fluid from power plant Or other nodes and recoils of such heat into the atmosphere through the radiator. IN air system Air is used as a working cooler. In both options there are their advantages and disadvantages.
However, a cooling system with liquid circulation was larger than distribution.
Air So.
Aerial cooling
The main advantages of this layout include the simplicity of the design and maintenance of the system. Such with practically does not increase the mass power aggregate, as well as not capricious to changes in ambient temperature. The negative includes a significant selection of motor power with a fan drive, elevated level noise when working, badly balanced heat removal from separate nodes, the impossibility of using the engine block system, the impossibility of accumulating the heat of heat for further use, for example, heating the cabin.
Liquid SO
Cooling fluid
System using heat removal using special fluid Due to its design, it can effectively get unnecessary heat from the mechanisms and individual details of the structure. In contrast to air, the engine of the engine cooling system with liquid contributes to a faster set of operating temperature at startup. Also, the motors with antifreeze are significantly quieter and are subject to smaller detonation.
Cooling system elements
Consider in more detail how the engine cooling system works on modern cars. There are no significant differences between gasoline and diesel engines in this regard.
As a "shirt" for cooling the motor, the structural cavities of the cylinder block are performing. They are located around zones from which it is necessary to distinguish heat. For a faster removal, a radiator is installed consisting of curved copper or aluminum tubes. A large number of additional edges accelerate the heat exchange process. Such ribs increase the cooling plane.
Before the radiator, the fan fan is installed. The influx of cooler streams begins after the electromagnetic coupling is closed. It turns on when fixed temperature values \u200b\u200bis reached.
Work thermostat
The continuity of cooling fluid circulation is ensured by the operation of the centrifugal pump. The belt or gear gear for it receives rotation from the power plant.
The thermostat is engaged in adjusting the flow directions.
If the coolant temperature is not high, the circulation passes through a small circle, without inclusion in it with the radiator. If the permissible thermal mode is exceeded, the thermostat is powered by a large circle with the participation of the radiator.
For closed hydraulic Systems Interesting the use of expansion tanks. Such a tank is provided in from the car.
Circulation of coolant
Salon Warming is performed using a heater radiator. Warm air in this case It does not go into the atmosphere, but it starts inside the car, creating comfort to the driver and passengers in the cold season. For greater efficiency, such an element is installed almost at the outlet of the liquid from the cylinder block.
The driver receives information about the state of the cooling system using the temperature sensor. Signals also go to the control unit. It can independently connect or turn off the actuators to comply with the balance in the system.
System work
Antifreeze with multiple additives, including anti-corrosion, are used as cooling fluids. They help increase the durability of the nodes and parts used in CO. Such a liquid is forcibly pumped through the centrifugal pump system. Begins to move from the cylinder block, the hottest point.
Initially, there is a movement on a small circle with a closed thermostat without entering the radiator, because it is not yet recruited working temperature For motor. After entering the operating mode, the circulation occurs in a large circle, where the radiator can be cooled by the oncoming stream or using the fan connected. After that, the fluid returns to the "shirt" around the cylinder block.
There are cars using two cooling circuits.
The first lowers the temperature of the motor, and the second take care of the influxing air, cooling it to form the fuel mixture.
