The Functions and Types Of Car Clutch
The clutch is installed between the engine and the transmission. It is a component in the transmission system that is directly connected to the engine. It is responsible for engaging and cutting off the power transmission between the engine and the transmission.The basic requirements for a clutch are: the active part and the driven part can be temporarily separated, and can be gradually connected, and relative slip may occur during the transmission process.
Its specific functions are as follows:
- ① Ensure the car starts smoothly. When the car starts, the driver slowly lifts the clutch pedal to gradually engage the main and driven parts of the clutch. When the driving force is enough to overcome the starting resistance of the car, the car will gradually accelerate from a standstill to achieve a smooth start.
- ② Ensure that the transmission shifts smoothly. When a car is driving, the transmission system needs to continuously change gears to adapt to changing driving conditions. For ordinary gear transmissions, the gear pairs of different gears need to exit or enter mesh when shifting. This requires depressing the clutch pedal before shifting, interrupting the power transmission of the engine, so that the original gear pair exits mesh, and the new gear pair simultaneously The speeds of the meshing parts are gradually equalized, so the impact is reduced when entering mesh, making the shifting work smooth.
- ③Prevent the transmission system from being overloaded. When the car is braking in an emergency, if there is no clutch, the engine speed will drop sharply due to its rigid connection with the transmission system, and all its moving parts will generate a large inertial moment, which will cause the transmission system to overload and damage its parts. With the clutch, when the load on the transmission system exceeds the maximum torque that the clutch can transmit, the clutch will eliminate this danger through relative movement (slip) between the main and driven parts, thereby achieving the purpose of overload protection.
Types of automobile clutch
Automobile clutches mainly use friction plate clutches, which rely on the friction between the main and driven plates for transmission.
Mechanical clutch is the most basic type of clutch, which mainly relies on contact and friction between friction plates to transmit torque. When the clutch pedal is depressed, the friction plate is combined or separated from the flywheel (or pressure plate) through the operating mechanism, thereby engaging or cutting off the power transmission between the engine and the transmission system.
According to the control method
1 Spring clutch
1.1 Diaphragm spring
A clutch that uses a diaphragm spring as a compression spring is called a diaphragm spring clutch.
Diaphragm spring clutches are also divided into push type diaphragm spring clutches and pull type diaphragm spring clutches.
Its structure consists of clutch cover and pressure plate assembly, clutch driven plate assembly, clutch release bearing and flywheel.
Features: The diaphragm spring clutch has large torque capacity and is relatively stable; 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 to the rotation axis of the clutch, so its pressing force will not be affected by centrifugal force and is very suitable for high-speed rotation. And the technological level of manufacturing diaphragm springs continues to improve, so this kind of clutch is used more and more in automobiles.
1.2 Surround cloth spring
Circumferential spring clutches are currently mainly used in commercial trucks. Structurally, the coil springs are arranged in concentric circles along 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 circumferential spring clutch is linear. When the friction plate is worn, the spring stretches and the pressing force decreases, which is very detrimental to the reliable torque transmission of the clutch. For this reason, a structure that combines circumferential coil springs can be used instead, and a spring is placed inside the large spring. The two rotate in opposite directions and the spring stiffness is also different.
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, and should increase as the diameter of the friction plate increases, sometimes even arranged in two rows.
1.3 Central spring
A structure that uses 1-2 cylindrical coil springs or a conical coil spring with a rectangular cross-section as a compression spring and is placed in the middle of the clutch is called a central spring clutch.
Its structural components include: pressure plate, clutch cover, adjustment ring, elastic pressure rod, fan blade, compression spring, release bearing, release sleeve, and pressure plate release spring.
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 temper and fail.
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 small spring force can be used to obtain a sufficiently large pressing force on 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.
2 Hydraulic clutch
Hydraulic clutches use fluid, usually oil, to transfer pressure and power. This kind of clutch is usually used in large trucks and some special vehicles. When the clutch pedal is depressed, the clutch is engaged or disengaged through the hydraulic system. Hydraulic clutch has the advantages of light operation and smooth combination, but its structure is relatively complex and its maintenance cost is high.
3 Electromagnetic clutch
The electromagnetic clutch uses electromagnetic force to control the combination and separation of the clutch. This kind of clutch is usually used in some special occasions, such as occasions where starting is frequent and rapid combination and separation are often required. The electromagnetic clutch has the advantages of fast response and precise control, but it is costly and requires a stable power supply.
4 pneumatic clutch
Pneumatic clutches use compressed air to transmit power and control the combination and separation of the clutch. This kind of clutch is usually used in large trucks and some special vehicles. The air pressure clutch has the advantages of small operating force and smooth combination, but it requires a stable air pressure supply and its structure is relatively complex.