Introduction to Automotive Clutch
The clutch is located in the flywheel housing between the engine and the gearbox. The clutch assembly is fixed to the rear plane of the flywheel with screws. The output shaft of the clutch is the input shaft of the gearbox. During driving, the driver may press or release the clutch pedal as needed to temporarily separate and gradually engage the engine with the gearbox to cut off or transmit the power input from the engine to the transmission.
A mechanical part that can engage or disengage the drive shaft with the slave shaft at any time. Can be used to control the machine drive system start, stop, speed and commutation and so on. Clutch a wide range, according to the nature of work can be divided into: ① operating clutch. (Using friction force transmission torque), air flexible clutch (with the friction force transmission torque), the friction clutch (using friction transmission torque), the air flexible clutch (with the friction force transmission torque), the air flexible clutch Compressed air to shrink or shrink to manipulate the friction clutch or clutch), an electromagnetic slip clutch (magnetic force generated by the excitation current to transmit torque), a magnetic clutch (magnetized by a magnetizing coil to form a magnetic powder chain to transmit torque). ② automatic clutch. With a simple mechanical method to automatically complete the joint or separate action, and is divided into safety clutch (when the transmission torque reaches a certain value when the drive shaft can be automatically separated to prevent overload, to avoid damage to important parts of the machine), centrifugal clutch When the speed reaches a certain value, due to the role of centrifugal force can make the drive shaft between the self-coupling or more than a certain speed can be separated after their own), directional clutch (also known as overrunning clutch, the use of ratchet - pawl engagement or roller, wedge Wedge action unidirectional transfer movement or torque, when the drive shaft reverse or speed lower than the driven shaft, the clutch will automatically separate).
The function of the car clutch
1. Make sure the car starts smoothly
Before the start of the car in a quiescent state, if the engine and the gearbox is rigid connection, once hung up the file, the car will suddenly connected to the power suddenly forward, not only will cause damage to the parts, and the driving force is not enough to overcome the car forward Resulting in a huge inertial force, so that the engine speed dropped sharply and turn off. If the clutch is temporarily separated from the gearbox by the clutch at the start, and then the clutch is gradually engaged, the torque coming out of the clutch can be gradually increased from zero due to the presence of the friction between the active part and the driven part of the clutch, And the driving force of the car has gradually increased, so that the car started smoothly.
2. Easy to shift
During the car driving process, often used for different gearbox stalls to adapt to changing driving conditions. If there is no clutch to separate the engine from the gearbox, the gears engaged in the gearbox will not be removed due to the load, and the pressure between the meshing surfaces is large and difficult to separate. Another treatment of the gear will be due to the two peripheral speed and difficult to engage. Even if forced into the engagement will produce a large tooth end impact, easy to damage the parts. The clutch and the gearbox are temporarily separated and separated by a clutch, and the pair of gears originally engaged are easily removed due to the load being removed and the pressure between the mating surfaces is greatly reduced. And the other pair of gears to be engaged, since the driving gear and the engine after the separation of inertia is very small, the use of appropriate shift action can be engaged in the gear cycle speed equal to or equal to the same, so as to avoid or reduce the impact between the gears.
3. Prevent the driveline from overloading
When the car is in emergency braking, the wheel suddenly decelerates abruptly, and the drive train connected to the engine is kept at its original speed due to the inertia of the rotation. This tends to produce an inertia moment far greater than the engine torque in the transmission system. The parts are easily damaged. As the clutch is to rely on friction to transmit torque, so when the drive train load exceeds the torque can pass the torque, the clutch main and driven part will automatically slip, and thus played a role in preventing the transmission line overload The
The working principle of the car clutch
The active part of the clutch and the driven part of the friction between the contact surface, or with the liquid as a transmission medium (hydraulic coupling), or with a magnetic drive (electromagnetic clutch) to transmit torque, so that between the two Temporary separation, but also gradually joined in the transmission process allows two parts to rotate each other.
Currently widely used in the car is a spring-loaded friction clutch (referred to as friction clutch).
The torque generated by the engine, through the flywheel and pressure plate and the driven plate of the friction surface, passed to the driven plate. When the driver depresses the clutch pedal, the large end of the diaphragm spring is driven by the transmission of the machine, and the driven part is separated from the active part.
The friction clutch should meet the following basic requirements:
(1) to ensure that the engine can send the maximum torque, and there is a certain transmission torque spare capacity.
(2) can be separated, thoroughly separated, soft when joined, and has a good cooling capacity.
(3) The moment of inertia of the driven part is as small as possible. In this way, when the clutch is shifted, the speed of the part connected to the transmission input shaft is relatively easy to change, thereby reducing the impact between the gears.
(4) has the ability to mitigate the direction of rotation, the ability to decay the direction of vibration, and the noise is small.
(5) pressure plate and friction plate friction coefficient changes small, stable work.
(6) manipulation of effort, easy maintenance.
Classification of automobile clutches
National Standard for Clutch Classification GBT10043-2003
Automotive clutch friction clutch, torque converter (hydraulic coupling), electromagnetic clutch, and several. The friction clutch is divided into wet and dry type.
Hydraulic coupling by working fluid (oil) to transmit torque, shell and pump wheel as a whole, is the initiative; turbine and pump wheel is relative, is the follower. When the pump wheel speed is low, the turbine can not be driven, between the active and the follower in a separate state; with the pump wheel speed increases, the turbine was driven, between the active and the follower in the joint state.
The electromagnetic clutch controls the clutch engagement and separation by turning on and off the coil. If the magnetic powder is placed between the active and the follower, the joint force between the two can be enhanced. Such a clutch is called a magnetic powder type electromagnetic clutch.
At present, with the manual transmission in line with the vast majority of the clutch for the dry friction clutch, according to the number of its drive plate, divided into single-disc, double-disc and multi-disc type several.
Wet friction clutch is generally multi-disc type, immersed in oil to facilitate heat dissipation. A number of coil springs are used as the compression springs and the springs are distributed along the circumference of the platen as a cloth spring clutch (as shown). A clutch with a diaphragm spring as a compression spring is called a diaphragm spring clutch.
Automatic clutch
With the application of electronic technology in the car, an automatic clutch system has also entered the automotive field. This clutch controlled by the control unit (ECU) has been applied to some cars, making an important step in the manual transmission shift - the disengagement and engagement of the clutch can be done automatically and in a timely manner, simplifying the driver's handling.
Conventional clutch is divided into two kinds of cable and hydraulic, automatic clutch is also divided into two types: mechanical motor automatic clutch and hydraulic automatic clutch. The ECU of the mechanical motor type automatic clutch is equipped with a signal such as an accelerator pedal, an engine speed sensor and a vehicle speed sensor. The servo motor is driven by a command to drive the servo motor and the clutch is driven by mechanical means such as a rod. The hydraulic automatic clutch is driven by the ECU to drive the motor Hydraulic system, through the hydraulic control clutch action.
The hydraulic automatic clutch adds an electronic control unit (ECU) and a hydraulic actuator to the conventional diaphragm clutch, and the pedal clutch clutch cylinder is controlled by a switch device to control the motor pump to operate the clutch cylinder piston. The transmission control unit (ECU) is integrated with the engine control unit (ECU), and the sensor feedback information is calculated according to the sensor feedback information such as the accelerator pedal, the transmission gear position, the transmission input / output shaft speed, the engine speed and the throttle opening degree. Good engagement time and speed.
The actuator of the automatic clutch is composed of an electric oil pump, a solenoid valve and a clutch cylinder. When the ECU sends a command to drive the electric oil pump, the high pressure oil produced by the electric oil pump is sent to the clutch cylinder through the solenoid valve. Through the ECU to control the amount of current solenoid valve to control the flow of oil and oil channel conversion, to achieve the clutch cylinder piston movement, thus completing the car start, shift when the clutch action.
The ECU with an automatic clutch device has an advantage in terms of operational economy compared to automatic transmission (AT) and CVT vehicles because its transmissions are also manual transmissions, so fuel consumption is low and manufacturing costs are Lower than AT and CVT. Of course, the ease of car control will be inferior to AT and CVT, after all, it is equipped with manual transmission, still have to manually shift.