Function of clutch
Make sure the vehicle starts smoothly
This is the main function of the clutch. It is natural to start the engine before the car starts. When the car starts, it accelerates gradually from a completely static state. If the transmission system (connecting the whole vehicle) is rigidly connected to the engine, once the transmission is engaged, the vehicle will suddenly rush forward, but will not start. This is because the car has a lot of inertia from standstill to forward impact, which will cause great resistance to the engine. Under the action of this inertia resistance moment, the engine speed suddenly drops below the lowest stable speed (usually 300-500RPM), and the engine will stop working, and of course, the car cannot start.
Therefore, we need the help of clutch. After the engine starts and before the car starts, the driver first steps on the clutch pedal, separates the clutch, separates the engine and transmission, puts the transmission into gear, then gradually releases the clutch pedal, and gradually engages the clutch. During the engagement process, the resistance torque of the engine increases gradually, so the accelerator pedal should be stepped down gradually at the same time, that is, the fuel supply to the engine should be gradually increased, so that the engine speed will always be kept at the lowest stable speed without stalling. At the same time, as the engagement of the clutch increases, the torque transmitted by the engine to the drive wheel through the transmission system will gradually increase. When the traction force is enough to overcome the starting resistance, the vehicle will move from a stationary state and gradually accelerate.
Achieve smooth shift
In order to adapt to the changing driving conditions of the vehicle during driving, the transmission system often needs to shift to work. Shift of gear transmission is usually achieved by shifting or other shift mechanisms to push a pair of gears of the original gear out of the transmission, and then make the gear pair of the other gear run. Before shifting, the clutch pedal must be stepped down to interrupt the power transmission, so that the meshing pair of the original gear can be disengaged, so that the speed of the meshing part of the new gear can be gradually synchronized with the speed of the meshing part, so that the impact force when entering the meshing is greatly reduced, so as to achieve a smooth shift.
Protect the drive train from overload
When the vehicle is in the emergency braking state, if there is no clutch, the engine speed will decrease sharply due to the rigid connection with the transmission system. Therefore, all moving parts will generate large inertia torque (its value may greatly exceed the maximum torque sent by the engine during normal operation), which will cause loads on the transmission system that exceed its bearing capacity and damage the components. With the clutch, you can eliminate this danger by relying on the possible relative movement between the driving part and the driven part of the clutch. Therefore, we need the clutch to limit the maximum torque that the transmission system bears to ensure safety.
