The clutch is a component directly connected with the engine in the automobile transmission system, and its basic functions are:
1. When the car starts, the speed of the clutch is gradually close to that of the main and driven parts through the grinding between them to ensure that the car starts smoothly.
2. When the transmission shifts, the transmission of power is cut off by the rapid separation of the main and slave parts of the clutch to reduce the impact between the gear teeth and ensure the smooth work during the shift.
3. When the torque passed to the clutch exceeds the maximum torque it can transmit, there will be a slip between the main and slave parts to prevent the transmission system from being overloaded.
details are as follows
Before the car starts, the transmission should be in neutral position, and the connection between the engine and the drive wheel should be disconnected to remove the engine load. Then start the engine, and when the engine enters a stable idle condition, the transmission is put into a certain gear to make the car start. When the car starts, it accelerates gradually from a completely stationary state.
Because the transmission system is connected to the whole car, if it is rigidly connected to the engine, the transmission has just been put into gear, and the car will suddenly rush forward, but it cannot start. This is because the car will produce a large inertial force when it is at rest to rush forward, causing a large resistance moment to the engine. Under the action of this inertia resistance moment, the engine speed drops sharply to the lowest stable speed (generally 300 ~ 500r\/min) below the instant, the engine is turned off and can not work, of course, the car can not realize the start.
If the clutch is installed in the transmission system, after the engine starts, before the car starts, the driver first steps on the clutch pedal, separates the clutch, disengages the engine and the transmission system, and then puts the transmission in gear, and then gradually releases the clutch pedal, so that the clutch gradually engages. In the process of gradually engaging the clutch, the blocked torque of the engine gradually increases, so it should gradually step on the accelerator pedal at the same time, that is, gradually increase the fuel supply of the engine, so that the engine speed is always kept above the minimum stable speed, without stalling. As the tightness of the clutch gradually increases, the torque transmitted by the engine to the drive wheel through the transmission system gradually increases. When the driving force is sufficient to overcome the starting resistance, the car starts moving from a standstill and gradually accelerates. Therefore, to ensure that the car starts smoothly is the primary function of the clutch.
Another function of the clutch is to ensure that the transmission system works smoothly when shifting.
When the car is subjected to emergency braking, if there is no clutch, the engine will be rigorously connected to the transmission system and sharply reduce the speed, so that all the moving parts of it produce a large inertia torque, the value may greatly exceed the maximum torque issued by the engine during normal operation, which will cause the transmission system to exceed its carrying capacity of the load, so that its parts are damaged. When the clutch is installed, this danger can be eliminated by relying on the possible relative motion between the active and driven parts of the clutch. Therefore, the clutch also has a function of limiting the maximum torque of the transmission system to prevent the transmission system from being overloaded.
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No clutch in the automatic?
Some people think that they are not driving a manual transmission, there is no clutch.
That's not true.
There is only no \"clutch pedal\" on the automatic car, which is controlled by a computer program, and your left foot is liberated, but this does not mean that there is no clutch on the car (even if there is no clutch on the car, there must be a other part to play the role of the clutch, such as a hydraulic coupler).
When shifting gears, first step on the clutch to disengage the power, and the sensor immediately tells the ECU. The ECU determines that it may need to shift gears, that is, to temporarily remember and maintain the current engine speed, accelerator pedal position and fuel injection.
Shift gears, release clutch to return to full linkage, and the sensor immediately notifies the ECU. The ECU immediately monitors changes in engine speed and also looks to see if the accelerator pedal has changed. When it is found that the speed is reduced and its trend, and the accelerator pedal has no change or insufficient, it is immediately ordered to increase the injection speed to maintain or compensate. The gas pedal has changed, and then the operation of tracking the accelerator is shifted. This feature makes the shift process smooth, and the acceleration and deceleration smooth. It feels so good!
However, when the sensor cannot provide the change signal of the clutch opening and closing, such as some small three sensors are always in the \"on\" state signal. Then obviously, after the shift is completed, the ECU cannot know that when the load mutation causes the speed to fall and its trend, it cannot automatically increase the fuel injection speed compensation. Without this auxiliary role, the driving level is required. Novice or unfamiliar often semi linkage refueling is not good, the upshift after the loose clutch is too fast, the engine due to load mutation, the speed will fall and the car, then the urgent refueling door and rush. That is the so-called \"car drop\" phenomenon. Clutch specific sensor, output switching quantity, specially to the engine computer (ECU) to provide clutch on and off status signal. For the small three, its main role is to let the ECU know the dynamic loading situation, and perform auxiliary functions such as the engine speed shift buffer transition, speed mutation suppression, and energy efficiency control strategy to ensure that the engine performance is fully played. Make driving easy, improve handling and comfort.
Most of the middle and high-end models have the engine speed shift buffer transition function. Inhibit the engine speed drop and sudden rise caused by the shift, prevent the uncomfortable phenomenon such as stopping and falling, so that the acceleration and deceleration are smooth and smooth. This feature is also gradually adopted in low-end models to improve handling and comfort.