The fan is a consumer of engine power, the maximum is about 10% of the engine power. In order to reduce fan power consumption, reduce noise and wear and tear, prevent engine overcooling, reduce pollution and save fuel, more fan clutch.
2, the structure of the silicone oil fan clutch
Silicone oil fan clutch by the front cover, shell, active plate, slave plate, valve plate, the active shaft, bimetallic thermostat, the valve plate shaft, bearings, fans and other components. It is shown in the figure below.
The front cover, shell and follower plate are formed as one piece with screws and are mounted on the main shaft through bearings. The fan is mounted on the housing. The cavity between the follower plate and the front cover is the oil storage cavity, which is filled with silicone oil (the oil level is lower than the shaft centerline), and the cavity between the follower plate and the shell is the working cavity. The driven plate is fixedly connected with the driven shaft, and the driven shaft is connected with the pump shaft. There is an oil inlet hole A on the follower plate, which is normally closed by the valve piece, and if the valve piece is deflected, the oil inlet hole can be opened. The deflection of the valve blade is controlled by a bimetallic thermostat, and there is a tab on the follower plate to limit the maximum deflection angle of the valve blade. The outer end of the bimetallic thermostat is fixed to the front cover, and the inner end is stuck in the groove of the valve plate shaft. There is an oil return hole B on the outer edge of the follower plate and an oil leakage hole C in the center to prevent silicone oil from leaking around the valve spindle during static.
3, silicone oil fan clutch working principle
(1) when the engine cold start or small load work, the cooling water and airflow through the radiator temperature is not high, the oil inlet hole is closed by the valve plate, no silicone oil in the working chamber, the clutch is in the state of separation. When the main shaft is rotating, only due to the friction of the sealing felt ring and the bearing, the fan along with the shell in the main shaft is skidding in the air, and the rotational speed is extremely low.
(2) When the engine load increases, the temperature of the coolant and airflow through the radiator rises, and the thermostat is deformed by the heat and drives the valve blade shaft and valve blade to rotate. When the temperature of the airflow through the thermostat exceeds 338K (65 ℃), the oil inlet hole is completely open, so the silicone oil from the oil storage chamber into the working chamber. Silicone oil is very viscous, the active plate can use the viscosity of the silicone oil to drive the shell and fan rotation. At this time, the fan clutch is engaged, the fan speed increases rapidly.
In order not to make the working chamber of the silicone oil temperature is too high, the viscosity drops, so that the silicone oil in the shell of the continuous cycle. Because the active plate speed is higher than the follower plate, so by centrifugal force from the active plate thrown to the outer edge of the working chamber of the oil pressure than the outer edge of the oil storage chamber of oil pressure is high, the oil from the working chamber through the return hole B flow to the oil storage chamber, and the oil storage chamber by the oil inlet holes in time to the working chamber to replenish the liquid oil. In order to speed up the flow of silicone oil from the working cavity back to the oil storage cavity and shorten the fan disengagement time, an oil scraping protruding portion extends into the gap of the working cavity next to the oil return hole B of the follower plate 8, so that the pressure on the side of the oil return hole is increased and the oil return is accelerated.
(3) When the engine load is reduced, the temperature of the gas flowing through the thermostat is lower than 308K (35 ℃), the thermostat returns to its original state, the valve plate closes the oil inlet hole, the oil in the working chamber continues to flow from the oil return hole back to the oil storage chamber, until it is emptied. The fan clutch returns to the disengaged state.
4, failure emergency measures: driving, if the silicone oil fan clutch due to failure (such as oil leakage, etc.), you can loosen the hexagon socket screws, the locking plate pin inserted into the active plate holes, and then tighten the screws, so that the shell and the active shaft into a single unit, but at this time only rely on the pin drive, can not be used for a long time.