Fan Cluth

How does a fan cluth work?

1. Why is a fan clutch installed on a car?

Fan clutches include night-pressure type, electronic control, temperature-sensing silicone oil, etc. Let me explain the working principle of silicone oil fan clutch. Hope this helps. Silicone oil fan clutch uses silicone oil as the medium and uses the high viscosity of silicone oil to transmit torque. Using the air temperature behind the radiator, fan clutch disengagement and engagement is automatically controlled by a temperature sensor. When the temperature is low, the silicone oil does not flow, the fan clutch is disengaged, the fan speed slows down, and it basically runs idling. When the temperature is high, the viscosity of the silicone oil causes the fan clutch to engage, causing the fan and water pump shaft to rotate together, thereby regulating the engine temperature. The fan clutch is a device that automatically adjusts the fan air volume as the engine temperature changes. In this way, not only can the engine work at the most suitable temperature, but also the warm-up time can be shortened and the effective power of the engine can be improved. Fan clutch function: a. When the fan cooling is not needed, it will stop; b. When the fan cooling is not needed, its speed can be reduced; C. When fan cooling is required, it will rotate at high speed. d. Control the fan speed within an appropriate range to reduce noise and improve engine economy. Installation location: between the fan pulley and the cooling fan. Car fan clutch: Silicone fan clutch is almost used in cars. The fan clutch can prevent the fan from rotating when the engine water temperature is low. It will start to rotate when it reaches a certain temperature, lowering the water temperature, keeping the engine at a suitable operating temperature, and also saving a small part of the engine's power. As operating conditions change, the thermal conditions of the engine will also change. Therefore, the cooling intensity of the engine must be adjusted at any time. 2. For example, in hot summer, when the engine is working at low speed and heavy load and the coolant temperature is high, the fan should rotate at high speed to increase the cooling air volume and enhance the heat dissipation capacity of the radiator; while in cold winter, the coolant temperature is too cold. Or when the car is driving at high speed, there is strong head wind blowing through the radiator, and it is meaningless for the fan to continue to work. Not only is the engine power consumed in vain, but it also produces a lot of noise. Tests show that the water cooling system requires the fan to work only 25% of the time, and the fan works for even less time in winter. Therefore, it is very important to adjust the cooling intensity of the engine at any time according to the thermal conditions of the engine. Installing a silicone oil fan clutch between the fan pulley and the cooling fan is one way to achieve this adjustment. Because the cooling fan cannot run all the time! When the weather is cold in winter, if you turn on the fan when the car is cold, the water temperature will definitely not rise and it will be very cold! So it has a clutch! When the temperature is reached, it attracts the fan and turns it on!

2. There are several types of commonly used fan clutches

First: diaphragm spring clutch. A clutch with a diaphragm spring as a compression spring is called a diaphragm spring clutch. Diaphragm spring clutches are further divided into a. push type diaphragm spring clutch and b. pull type diaphragm spring clutch. Its structure consists of clutch cover and pressure plate assembly, clutch driven plate assembly, clutch release bearing and flywheel. Features: diaphragm spring clutch, large and stable torque capacity; easy to operate; simple and compact structure; good heat dissipation and ventilation performance; long service life of the friction plate. The installation position of the diaphragm spring is completely symmetrical with the rotation axis of the clutch, so its pressing force is not affected by centrifugal force and is very suitable for high-speed rotation. The technical level of manufacturing diaphragm springs is also constantly improving, so this type of clutch is increasingly used in automobiles. Second: peripheral spring clutch. Circular spring clutches are currently used primarily in commercial trucks. Structurally, the coil springs are arranged in concentric circles around the circumference of the pressure plate. The pressure plate, release lever and coil spring are all installed in the clutch cover to form the clutch cover assembly. The flywheel serves as an active friction surface of the clutch, and the other active friction surface is the pressure plate. Features: The coil spring used in the peripheral spring clutch is linear. When the friction plate wears, the spring stretches and the pressing force decreases, which is very detrimental to the reliable transmission of clutch torque. To this end, you can use a combination of spiral springs placed around the circumference. A spring is placed inside the large spring. The two rotate in opposite directions and have different spring stiffnesses. In order to ensure that the pressure distribution on the friction plate is as uniform as possible, the number of compression springs should not be too small. It should increase as the diameter of the friction plate increases, and sometimes it is even arranged in two rows. Third: Central spring clutch. A structural form in which 1-2 cylindrical coil springs or conical coil springs with rectangular cross-section are placed in the middle of the clutch as compression springs is called a center spring clutch. Its structural components include: pressure plate, clutch cover, adjustment ring, elastic pressure rod, fan blade disc, compression spring, release bearing, release sleeve, and pressure plate release spring. What types of clutches are commonly used in cars? What are the characteristics? Features: The compression spring of the central spring clutch is not in direct contact with the pressure plate, so the heat generated by the pressure plate due to friction will not be directly transferred to the spring, causing it to fail due to tempering. The pressing force of the central spring acts on the pressure plate through the lever system and is amplified according to the lever ratio, so a smaller spring force can obtain sufficient pressing force of the pressure plate. The middle section of the elastic pressure rod of some central spring clutches is often made into a blade shape and becomes a fan blade, which is beneficial to the ventilation and heat dissipation of the clutch. 1. Clutch fan The clutch fan is equipped with a fan clutch between the pulley of the fan blade and the hub. The working state of the fan is adjusted by the separation and engagement of the clutch. This not only ensures the normal operating temperature of the engine, but also reduces the power loss of the engine and reduces fuel consumption. Common clutch fans include electromagnetic clutch fans and silicone oil clutch fans. Electromagnetic fan clutch, when the coolant temperature reaches the specified value, the coolant temperature sensor switch or the air temperature sensor switch automatically connects the circuit, and the clutch coil is energized to form a closed magnetic circuit to generate magnetic pull, which engages the armature with the pulley and the fan works; when cooling After the liquid temperature drops, the induction switch is disconnected, the armature is quickly reset under the action of the diaphragm spring, the clutch is separated, and the fan stops working. When the engine temperature is high, the silicone oil clutch fan is turned off, and the fan works to reduce the radiator temperature; when the engine temperature is low, the fan clutch is automatically disengaged and the fan does not rotate, saving engine power and increasing the cooling water temperature. The rotation of the fan does not mean whether the fan clutch is faulty, because whether it is a fault or a normal fan clutch, it will rotate with the water pump pulley when it is disengaged. You can tell whether the fan clutch is normal by listening to the sound of the fan. For a normal fan clutch, when the engine water temperature is higher than 86, the fan will make a normal working sound, but if the fan clutch fails, the sound will be much smaller at this time.

When the fan clutch fails, the fan will not rotate when the engine water temperature is high. At this time, with the engine stalled, loosen the nut, insert the locking piece into the pin hole of the driving shaft, and fix the fan and the driving shaft. Do not use the fan clutch to force the fan to rotate; wait for an opportunity to repair the fan clutch, and then restore the automatic clutch function of the fan clutch. 2. Ordinary cooling fan The fan is located between the radiator and the fuselage. It is installed on the same shaft as the water pump and is driven by the pulley on the crankshaft. The fan and the pulley hub are connected with bolts, and the engine crankshaft pulley directly or indirectly drives the fan to rotate. The tightness of each belt should be adjusted according to regulations. The tightness of the fan belt is too loose, which causes the fan pulley speed to decrease, the heat dissipation of the water tank to weaken, the diesel engine operating temperature to rise, and the generator output current to decrease or become unstable. However, the tightness of the fan belt is not always better. Excessive tightness will cause the bearing to be overloaded, increase wear, and increase power consumption. It will also bend the water pump shaft, elongate and deform the belt, and shorten the service life. Therefore, the fan belt should be kept appropriately tight and adjusted if necessary. How to check the tightness of the belt: Use your fingers or a ruler to press the middle of the belt with a pressure of 30 to 50N, and the belt should be deflected 10 to 20mm. Some engines are equipped with two belts, and some engines are equipped with three or four belts. Each pulley train should be on the same plane, and the belt should not be twisted during installation. If the belt is severely worn or broken, it should be replaced in time. If there are two fan belts, they must be replaced at the same time to avoid uneven tightness and uneven force, which may cause malfunction. 3. The working principle of electronically controlled fans. This type of fan is driven by its own fan motor. The circuit switch of the motor is controlled by the fan sensor (temperature control switch) installed in the lower water chamber of the radiator. When the radiator water temperature is above 86~90℃, the temperature control switch turns on the fan motor circuit to rotate the fan to accelerate the cooling of the radiator. When the radiator water temperature drops below 81~85℃, the fan sensor is disconnected and the fan motor The circuit breaks and the fan stops rotating. The clutch is located in the flywheel housing between the engine and the gearbox. The clutch assembly is fixed on the rear plane of the flywheel with screws. The output shaft of the clutch is the input shaft of the gearbox. While the car is driving, the driver can depress or release the clutch pedal as needed to temporarily separate and gradually connect the engine and the transmission to cut off or transmit the power input from the engine to the transmission. Mechanical parts that can join or separate the driving shaft and the driven shaft at any time according to work needs. It can be used to control the starting, stopping, speed changing and reversing of the machine transmission system. There are many types of clutches, which can be divided according to their working properties: ① Operated clutches. The control methods include mechanical, electromagnetic, pneumatic and hydraulic, etc., such as embedded clutch (transmitting torque through the fitting of teeth, teeth or keys), friction clutch (transmitting torque using friction force), air flexible clutch (using A clutch that expands and contracts the compressed air tire to control the engagement or separation of friction parts), electromagnetic slip clutch (uses an excitation current to generate magnetic force to transmit torque), and magnetic powder clutch (uses an excitation coil to magnetize magnetic powder to form a magnetic powder chain to transmit torque). ②Automatic clutch. A simple mechanical method is used to automatically complete the coupling or separation action, which is divided into safety clutch (when the transmission torque reaches a certain value, the transmission shaft can automatically separate, thereby preventing overload and avoiding damage to important parts in the machine), centrifugal clutch (when the driving shaft When the speed reaches a certain value, due to the action of centrifugal force, the transmission shafts can connect themselves or separate themselves after exceeding a certain speed), directional clutch (also called overrunning clutch, which uses the meshing of ratchet and pawl or the engagement of rollers and wedges) The wedging action transmits motion or torque in one direction. When the driving shaft reverses or the speed is lower than the driven shaft, the clutch automatically separates). How many types of commonly used fan clutches are there? The fan clutch can automatically control the working status of the fan according to the cooling water temperature, thereby reducing engine power loss and also realizing automatic adjustment of cooling intensity. There are three types, silicone oil type, mechanical type, and electromagnetic fan clutch for various types and brands. , various engines mainly use silicone oil as the medium. The simplest monitoring method: start the car when it is cool and idle at a high speed. If you hear the engine noise becomes significantly smaller in about 1 minute, it means that the fan is disengaged, indicating that there is no problem with the clutch. The characteristic of the silicone oil clutch is that it is fully engaged when the car is first turned on, but will disengage in about 1 minute. The reason why the idle speed is high is to clearly judge the status of the fan through the noise. There are many powerful types of fans, so you have to look at which one you need. For different fan clutch types, its range of use is different for different fans, and there are many applications for this thing just by sealing it. , such as electric fans at home or fans in some mining machines, etc. There are two commonly used red oak clutches. One is the mechanical fan clutch, which can be rotated by just driving it with a belt. The other is the silicone oil clutch. The silicone oil clutch is driven by a belt but has a clutch inside it. If the engine water temperature is high, the valve's rotation speed will be fast. If the engine water temperature is low, its rotation speed will be very slow.