Car engine cooling system: device and principle of operation

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

The engine cooling system in the car is designed to protect the working unit from overheating and thereby 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 in the cooling of the internal combustion engine can be fatal for the unit itself, up to the complete failure of the cylinder block. Damaged nodes may no longer be subject to restoration work, their maintainability will be equal to zero. It is necessary to treat the operation with all care and responsibility and carry out periodic flushing of the engine cooling system.

By controlling the cooling system, the car owner directly takes care of the "he alth of the heart" of his iron "horse".

Appointment of the cooling system

The temperature in the cylinder block when the unit is running can rise to 1900 ℃. Of this volume of heat, only a part is useful and is used in the required operating modes. The rest is taken out by the cooling system.engine compartment. Increasing the temperature regime above the norm is fraught with negative consequences that lead to burnout of lubricants, violation of technical clearances between certain parts, especially in the piston group, which will lead to a decrease in their service life. Overheating of the engine, as a result of a malfunction of the engine cooling system, is one of the reasons for the detonation of the combustible mixture supplied to the combustion chamber.

Overcooling of the engine is also undesirable. In a "cold" unit, there is a loss of power, the oil density increases, which increases the friction of non-lubricated components. The working combustible mixture partially condenses, thereby depriving the walls of the cylinder of lubrication. However, the surface of the cylinder wall undergoes a corrosion process due to the formation of sulfur deposits.

The engine cooling system is designed to stabilize the thermal conditions necessary for the normal functioning of the vehicle's engine.

Types of cooling system

The engine cooling system is classified according to the method of heat dissipation:

• cooling with liquids in a closed type;
• open type air-cooled;
• combined (hybrid) heat dissipation system.

Currently, air cooling in cars is extremely rare. Liquid can be open type. In such systems, heat is removed through the steam pipe to the environment. The closed system is isolated from the outsideatmosphere. Therefore, the pressure in the cooling system of this type of engine is much higher. At high pressure, the boiling threshold of the cooling element increases. The refrigerant temperature in a closed system can reach 120℃.

Air cooling

Natural forced air cooling is the simplest way to remove heat. Engines with this type of cooling emit heat into the environment using 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 installation of an efficient and compact unit at the same time. In the engine cooling system, air is supplied unevenly to all parts, and then the possibility of local overheating must be avoided. Following the design features, the cooling fins are mounted in those places of the engine where the air masses are the least active, due to aerodynamic properties. Those parts of the motor that are most susceptible to heat are placed towards the air masses, while the "colder" sections are placed at the back.

Forced air cooling

Motors with this type of heat dissipation are equipped with a fan and cooling fins. Such a set of structural units allows you to artificially force air into the engine cooling system forcooling fins. A protective casing is installed above the fan and fins, which participates in the direction of air masses for cooling and prevents heat from entering from the outside.

The positive aspects in this type of cooling are the simplicity of design features, low weight, the absence of refrigerant supply and circulation units. The disadvantages are the high noise level of the system and the bulkiness of the device. Also, in forced air cooling, the problem with local overheating of the unit and diffuse airflow has not been solved, despite the installed casings.

This type of engine overheating warning was actively used until the 70s. Forced air type engine cooling system operation has been popular on small vehicles.

Cooling with liquids

The liquid cooling system is by far the most popular and widespread. The process of heat removal takes place with the help of a liquid refrigerant circulating through the main elements of the engine through special closed lines. The hybrid system combines the elements of air cooling at the same time as liquid. The liquid is cooled in a radiator with 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 produces a minimum level of noise during operation. This type collects heat everywhere and removes it from the engine with highefficiency.

According to the method of movement of the liquid refrigerant, systems are classified:

• forced circulation - fluid movement occurs with the help of a pump that is part of the engine and the cooling system itself;
• thermosiphon circulation - the movement is carried out due to the difference in the density of the heated and cooled refrigerant;
• combined method - fluid circulation operates simultaneously in the first two ways.

Engine cooling system device

The liquid cooling design has the same structure and elements for both gasoline and diesel engines. The system consists of:

• radiator block;
• oil cooler;
• fan, shroud installed;
• pumps (pump with centrifugal force);
• tank for expansion of heated fluid and level control;
• Refrigerant circulation thermostat.

When flushing the engine cooling system, all these nodes (except the fan) are affected for more efficient further work.

Coolant circulates through lines inside the block. The totality of such passages is called the "cooling jacket". It covers the most heat-prone areas of the engine. The refrigerant, moving along it, absorbs heat and carries it to the radiator block. Cooling down, he repeats the circle.

System operation

One of the main elements in the device of the cooling systemengine is considered a radiator. Its task is to cool the refrigerant. It consists of a radiator crate, inside which tubes are laid for the movement of fluid. The coolant enters the radiator through the lower pipe and exits through the upper one, which is mounted in the upper tank. On top of 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 liquid enters the expansion tank, attached separately in the engine compartment.

Also on the radiator is a temperature sensor that signals the driver about the maximum heating of the liquid through a device installed in the cabin 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 temperature of the coolant is reached, or it works forcibly from the drive with a pump.

The pump ensures constant circulation of coolant throughout the system. The pump receives rotational energy by means of a belt drive from the crankshaft pulley.

The thermostat controls the large and small circle of refrigerant circulation. When the engine is started for the first time, the thermostat circulates fluid in a small circle so that the engine unit warms up to operating temperature faster. After that, the thermostat opens a large circle of the engine cooling system.

Antifreeze or water

Water or antifreeze is used as the coolant. Modern car owners have become increasinglyapply the latter. Water freezes at sub-zero temperatures and is a catalyst in corrosion processes, which negatively affects the system. The only advantage is its high heat dissipation and, perhaps, availability.

Antifreeze does not freeze when cold, prevents corrosion, prevents sulfur deposits in the engine cooling system. But it has a lower heat transfer, which negatively affects the hot season.

Faults

The consequences of a cooling failure are overheating or hypothermia of the engine. Overheating can be caused by insufficient fluid in the system, unstable pump or fan operation. Also the thermostat malfunctioning when it should open a large cooling circle.

Failures in the engine cooling system can be caused by severe contamination of the radiator, slagging of lines, poor performance of the radiator cap, expansion tank or low-quality antifreeze.