How electric fans work
When the engine is in the early stages of operation and at low temperatures, or when the car is driving at high speed and there is cold air blowing against the radiator, the fan can be operated without using the fan to blow air to the radiator to cool it. In order to ensure reliability, the electric fan uses the engine water temperature sensor to control the timing of the fan's air supply. The use of electric fans can improve engine preheating performance, reduce fuel consumption and reduce fan noise. Generally, the electric fan should not rotate at idle speed. The structure of an electric fan is mainly composed of a motor, a breaker, a water temperature switch, etc. When the water temperature is lower than 93°C, the water temperature switch is connected to the fan breaker path, and under the suction of the magnet coil, the contact is disconnected, so that the motor is not energized and the fan does not rotate; when the water temperature exceeds 93°C, the water temperature switch is disconnected. There is no current in the breaker coil, the contacts are closed, the fan motor is energized, and the fan rotates to deliver air.
Working principle of torque converter fan
This temperature-controlled torque converter cooling fan can adjust the cooling fan speed according to changes in the temperature of the air flowing through the radiator. When the temperature is low, the fan rotates slowly, which can improve the engine preheating conditions and reduce noise. When the engine temperature rises, the fan rotates faster, thus accelerating cooling.
The structure of a hydraulic torque converter fan is: the front end of the hydraulic torque converter has a torque converter rotor, the cover and shell of the torque converter are connected to the fan with screws, and the main hydraulic torque converter shaft is connected to the converter through a bearing. The twister cover is connected. The oil storage chamber and working chamber of the torque converter are filled with silicone oil, and there is a separator between the two chambers. There are silicone oil and oil return holes on the separator, and the bimetallic sheet controls the opening and closing of these holes. In addition, there is a communication hole connecting the oil storage chamber and the working chamber around the rotor shell.
(1) When the temperature of the air passing through the radiator is lower than 60°C, due to the shrinkage of the bimetallic sheet, the oil return hole on the separator is closed. When the torque converter rotor shaft rotates, there is pump oil on the toothed surface around the rotor. Function, the silicone oil in the working chamber enters the oil storage cylinder through the communication hole, thereby reducing the silicone oil in the working chamber and increasing the slip rate, that is, the speed of the fan pulley is 4000r/min, while the fan speed is only 800r/min.
(2) When the temperature of the air passing through the radiator exceeds 60°C, the bimetal strip stretches, opening the oil return hole on the separator. The silicone oil returns to the working chamber through the oil return hole under the action of centrifugal force, reducing the amount of silicone oil in the working chamber. As it increases, the slip rate decreases and the fan speed increases. The fan pulley speed is 4000r/min, and the fan speed is 2000r/min. Since the fan speed is controlled by the amount of silicone oil inside the torque converter, once there is silicone oil leakage, the silicone oil in the working chamber will decrease, which will cause the fan speed to drop and the engine to overheat.
Working principle of silicone oil fan clutch
Silicone oil fan clutch uses silicone oil as the medium and utilizes the high viscosity characteristics of silicone oil to transmit torque. The temperature of the air behind the radiator is used to automatically control the separation and engagement of the fan clutch through the temperature sensor. When the temperature is low, the silicone oil does not flow, the fan clutch is separated, and the fan speed slows down, basically idling. When the temperature is high, the viscosity of the silicone oil causes the fan clutch to engage, so the fan and water pump shaft rotate together to regulate the engine temperature.
Silicone oil fan clutch and temperature sensing elements are bimetallic coil spring temperature sensors. Its working process:
(1) When the temperature of the air flowing through the radiator rises, the bimetal thermometer is heated and deformed, forcing the valve shaft to rotate and opening the oil inlet hole on the driven plate. The silicone oil stored between the driven plate and the front cover flows into the working chamber between the active plate and the driven plate, the clutch is engaged, and the fan speed increases. The higher the air temperature, the larger the opening of the oil inlet hole, and the faster the fan speed.
(2) When the temperature of the air flowing through the radiator drops, the bimetal thermometer returns to its original state, and the valve plate closes the oil inlet hole. Under the action of centrifugal force, the silicone oil returns from the working chamber to the oil storage chamber through the oil return hole, and the clutch is separated. , the fan speed becomes very low.
