Engine cooling system: the device and the principle of operation
Engine cooling system in the carIt is designed to protect the unit from overheating and thus controls the performance of the entire engine block. Cooling is the most important function in the operation of an internal combustion engine.
The consequences of a malfunction of cooling ICE canto become fatal for the unit itself, up to the complete failure of the cylinder block. Damaged nodes may not be subject to repair works, their maintainability will be zero. It should be with all care and responsibility to take care of the operation and conduct periodic cleaning of the engine cooling system.
Controlling the cooling system, the car owner directly takes care of the "health of the heart" of his iron "horse".
Purpose of the cooling system
The temperature in the cylinder block while runningThe unit can rise to 1900 ℃. Of this amount of heat, only a part is useful and is used in the required modes of operation. The rest is output by the cooling system outside the engine compartment. An increase in the temperature regime above the norm is fraught with negative consequences that lead to the burning of lubricants, the violation of technical clearances between certain parts, especially in the piston group, which will lead to a reduction in their service life. Overheating of the motor, as a result of a malfunction of the engine cooling system, is one of the causes of the detonation of the combustible mixture supplied to the combustion chamber.
Subcooling the engine is also undesirable. In the "cold" unit there is a loss of power, the density of the oil rises, which increases the friction of ungreased assemblies. The working combustible mixture is partially condensed, thereby depriving the cylinder walls of the lubricant. At the same time, the wall surface of the cylinder undergoes a corrosion process due to the formation of sulfur deposits.
The engine cooling system is designed to stabilize the thermal regime necessary for the normal operation of the motor of the vehicle.
Types of cooling system
The engine cooling system is classified according to the heat removal method:
- cooling with liquids in a closed type;
- air cooling in open type;
- combined (hybrid) heat removal system.
Currently, air cooling incars is extremely rare. The fluid can be of an open type. In such systems, heat removal takes place through the steam pipe to the environment. The closed system is isolated from the external atmosphere. Therefore, the pressure in the engine cooling system of this type is much higher. At high pressures, the cooling threshold for the cooling element increases. The refrigerant temperature in the closed system can reach 120 ℃.
Natural supply air coolingmasses is the simplest way to remove heat. Motors with this type of cooling emit heat to the environment with the help of radiator fins located on the surface of the unit. Such a system has a huge lack of functionality. The fact is that this method directly depends on the small specific heat of air. In addition, there are problems with the uniformity of heat removal from the motor.
Such nuances prevent mounting at the same timeefficient and compact installation. In the engine cooling system, air flows unevenly into all parts, and then it is necessary to avoid the possibility of local overheating. Following the design features, the fins for cooling are mounted in those places of the engine, where the air masses are least active, due to aerodynamic properties. Those parts of the motor, which are most prone to heat, are arranged to meet the air masses, while the more "cold" areas are placed behind.
Forced air cooling
Motors with this type of excess heat removalequipped with a fan and cooling fins. Such a set of structural units allows artificially pumping air into the engine cooling system to blow cooling fins. Above the fan and ribs a protective casing is installed, which participates in the direction of air masses for cooling and prevents heat from entering from outside.
Positive moments in this type of coolingsimplicity of design features, low weight, absence of feeding and refrigerant circuits is assumed. The disadvantages are the high noise level of the system functioning and the unwieldiness of the device. Also in forced air cooling, the problem with the local overheating of the unit and the absent-mindedness of the blowing, despite the installed casings, has not been solved.
This type of engine overheat warningactively used until the 70's. The work of the engine cooling system with forced air type was popular on small vehicles.
Cooling with liquids
The liquid cooling system for today isthe most popular and widespread. The process of heat removal takes place with the help of liquid refrigerant circulating along the main engine elements via special closed highways. The hybrid system combines elements of air cooling with liquid at the same time. The liquid is cooled in a radiator having fins and a fan with a casing. Also, such a radiator is cooled by supply air masses when the vehicle is moving.
The liquid cooling system of the engine gives the minimum noise level during operation. This type collects heat all over the place and diverts it from the engine with high efficiency.
By the method of movement of liquid refrigerant systems are classified:
- forced circulation - the movement of the liquid occurs by means of a pump that is part of the engine and directly of the cooling system;
- thermosiphon circulation - movement is carried out due to the difference in the density of the heated and refrigerated refrigerant;
- a combined method - the circulation of a liquid acts simultaneously in the first two ways.
Engine Cooling System
The design of liquid cooling has the same structure and elements, both for a gasoline engine and for a diesel engine. The system consists of:
- radiator unit;
- oil cooler;
- fan, with installed casing;
- pump (pump with centrifugal force);
- The expansion tank for heated liquid and level control;
- refrigerant circulation thermostat.
When flushing the engine cooling system, all these nodes (except the fan) are affected for more efficient further operation.
The coolant circulates through the pipelinesinside the block. The totality of such passes is called the "cooling jacket". It covers the most exposed areas of the engine. Refrigerant, moving along it, absorbs heat and carries it to the radiator block. Cooling, he repeats the circle.
Operation of the system
One of the main elements in the device systemcooling the engine is considered a radiator. Its task is to cool down the coolant. It consists of a radiator grate, inside which tubes for the movement of liquid are laid. The cooling liquid enters the radiator through the lower branch pipe and exits through the upper one, which is mounted in the upper tank. Above the tank there is a neck, closed with a lid with a special valve. When the pressure in the engine cooling system increases, the valve opens slightly and the fluid enters the expansion tank, which is attached separately in the engine compartment.
Also on the radiator there is a temperature sensor,which signals the driver about the maximum heating of the liquid by means of a device installed in the passenger compartment on the information panel. In most cases, a fan (sometimes two) with a casing is attached to the radiator. The fan is activated automatically when the critical coolant temperature is reached or is forced from the drive with the pump.
The pump ensures a constant circulation of the cooling liquid throughout the system. Rotational energy of the pump is obtained by a belt drive from the crankshaft pulley.
The thermostat controls a large and small circlerefrigerant circulation. When the engine is started for the first time, the thermostat starts the liquid in a small circle so that the motor unit quickly warms up to the operating temperature. After that, the thermostat opens a large circle of the engine cooling system.
Antifreeze or water
The cooling water is wateror antifreeze. Modern car owners have increasingly used the latter. Water freezes at minus temperatures and is a catalyst in the corrosion processes, which negatively affects the system. The only advantage is its high heat dissipation and, perhaps, accessibility.
Antifreeze does not freeze in the cold, it preventscorrosion, prevents sulfur deposits in the engine cooling system. But it has a lower heat output, which affects negatively in the hot season.
The consequences of a cooling malfunction areoverheating or undercooling of the engine. Overheating can be caused by insufficient fluid in the system, unstable operation of the pump or fan. It is also an abnormal operation of the thermostat when it needs to open a large cooling circle.
Engine Cooling System Malfunctionsbe caused by severe radiator contamination, slagged lines, poor performance of the radiator cap, expansion tank or poor-quality antifreeze.