Since the operation of an internal combustion engine is associated not only with high mechanical loads, but also with critically high temperatures. To maintain the operating temperature of the power unit so that it does not fail due to heavy loads, each modification is equipped with a cooling system. There is air and liquid cooling. The motor cooling device is described in detail in another review .
To remove excess heat from the engine, liquid cooling systems have a radiator, and in some car models there is more than one. A fan is installed next to this element. Let's consider the purpose of this part, on what principle it works, how it is designed, and what to do if the mechanism fails en route.
What is a car radiator fan
When the motor is running, it generates a lot of heat. The cylinder block itself of a classic internal combustion engine is designed in such a way that there is a cavity in its walls that is filled with coolant (cooling jacket). The cooling system includes a water pump that operates while the crankshaft rotates. It is connected to the crankshaft via a timing belt (read about it in detail separately ). This mechanism creates circulation of working fluid in the system, due to which it removes heat from the walls of the engine.
Hot antifreeze or antifreeze goes from the engine to the radiator. This element appears to be in the form of a heat exchanger with a large number of thin tubes and cooling fins to increase the contact surface. More details about the design, types and operating principles of radiators are described here .
The radiator is only useful when the car is moving. At this time, a counter flow of cool air blows over the surface of the radiator, resulting in heat exchange. Of course, its effectiveness depends on the ambient temperature, but while driving this flow is still much cooler than the engine coolant.
The principle of cooling operation is at the same time its disadvantage - maximum cooling is only possible when the car is moving (cold air must penetrate the heat exchanger). In urban environments, it is impossible to ensure a constant process due to traffic lights and frequent traffic jams in megacities. The only solution to this problem is to create forced air injection onto the surface of the radiator. The fan performs exactly this function.
When the engine temperature rises, sensors are triggered and the heat exchanger is blown. More precisely, the blades are configured so that the air flow is not supplied against its movement, but is sucked in. Thanks to this, the device is able to increase the radiator airflow even while the car is moving, and when the vehicle is stationary, fresh air enters the engine compartment, rather than using the hot environment near the engine.
In older cars, the fan was rigidly mounted on the crankshaft, so it had a permanent drive. If in summer such a process only benefits the power unit, then in winter excessive cooling of the engine is not beneficial. This feature of the constant operation of the device prompted engineers to develop an analogue that would work only when it was required.
Cooling system channels clogged
Quite often, overheating is caused by congestion in the cooling system. This problem is often quite difficult to identify. Therefore, at the first sign of the fan turning on more frequently for no particular reason, you should first flush the system. In many cases this is enough. Also, just in case, you can bleed out the radiator.
Typically, cleaning the radiator and cooling channels is carried out together with replacing the antifreeze. To flush, drain the coolant. Then pour in a strong solution of citric acid or water with special additives. Then let the car run for half an hour. The used cleaning agent is drained and fresh antifreeze is added. In most cases, such a procedure helps to ensure that contaminants in the cooling system are eliminated.
Design and types of fan
Despite its key importance for the cooling system, this mechanism has a fairly simple design. Regardless of modifications, the fan design will consist of three elements:
- The casing, which is the basis of the mechanism, is installed on the radiator itself. The peculiarity of this element is that its design forces the air flow to work in only one direction - not to dissipate upon contact with the heat exchanger, but to pass through it. This casing design allows for more efficient cooling of the radiator;
- Impellers. Each blade is slightly offset from its axis, like any fan, but in such a way that when they rotate, air is sucked through the heat exchanger. Typically this element consists of 4 or more blades;
- Drive.
Depending on the device model, the drive may have a different type. There are three main varieties:
- Mechanical;
- Hydromechanical;
- Electric.
Let's consider each modification separately.
Mechanical drive
The mechanical drive has a simple device. Essentially, this type of fan has a permanent connection. Depending on the characteristics of the engine, it can be connected to the crankshaft through a pulley or through a timing belt. Starting the engine immediately leads to the operation of the impeller, and constant airflow is carried out on the heat exchanger and power unit.
