The automobile clutch is located in the flywheel housing between the engine and the transmission. 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 transmission. During the running of the car, the driver can step on or release the clutch pedal as needed to temporarily separate and gradually engage the engine and the gearbox to cut off or transfer the power input by the engine to the transmission.
Clutches are a common component in mechanical transmissions, which can disengage or engage the transmission system at any time. The basic requirements are: stable joint, rapid and thorough separation; easy adjustment and repair; small outline size; small quality; good abrasion resistance and sufficient heat dissipation capacity; easy operation and labor-saving, commonly used are tooth-inlay Two types of friction.
Automotive clutches include friction clutches, torque converters (hydraulic couplers), and electromagnetic clutches. Friction clutches are divided into two types, wet and dry.
Hydraulic Coupler Relying on working fluid (oil) to transmit torque, the casing is connected with the pump wheel as a whole, and it is the driving part; the turbine is opposite to the pump wheel and is the driven part. When the speed of the pump wheel is low, the turbine cannot be driven, and the driving member and the driven member are in a separated state; as the speed of the pump wheel increases, the turbine is driven, and the driving member and the driven member are in an engaged state.
Electromagnetic clutch The on and off of the coil are used to control the engagement and disengagement of the clutch. If magnetic powder is placed between the driving and the follower, the joint force between the two can be strengthened. Such a clutch is called a magnetic powder electromagnetic clutch. At present, most of the clutches that cooperate with manual transmissions are dry friction clutches. According to the number of driven disks, they are divided into single-disc, double-disc and multi-disc types. Wet friction clutches are generally multi-disc, immersed in oil for heat dissipation. Several coil springs are used as compression springs, and the clutches distributed along the circumference of the pressure plate are referred to as circumferential cloth spring clutches. A clutch using a diaphragm spring as a compression spring is called a diaphragm spring clutch.
Automatic clutch With the application of electronic technology to automobiles, an automatic clutch system has also entered the automotive field. This kind of clutch controlled by the control unit (ECU) has been applied to some cars, which makes an important step of manual transmission shifting-the disconnection and engagement of the clutch can be completed automatically and timely, simplifying the driver’s manipulation. There are two types of traditional clutches: cable and hydraulic, and automatic clutches are also divided into two types: mechanical motor automatic clutches and hydraulic automatic clutches. The ECU of the mechanical motor type automatic clutch collects signals such as the accelerator pedal, the engine speed sensor, and the vehicle speed sensor. After processing, it sends instructions to drive the servo motor and drives the clutch to operate by mechanical means such as a tie rod. The hydraulic automatic clutch is driven by the ECU to send signals The hydraulic system operates by hydraulically operating the clutch. The hydraulic automatic clutch adds an electronic control unit (ECU) and a hydraulic execution system to the commonly used diaphragm clutch. The pedal-operated clutch cylinder piston is replaced by a switch device to control the electric oil pump to operate the clutch cylinder piston. The transmission control unit (ECU) is integrated with the engine control unit (ECU). Based on sensor feedback information such as the accelerator pedal, transmission gear position, transmission input / output shaft speed, engine speed, and throttle opening, the clutch maximum is calculated. Best joining time and speed. The actuator of the automatic clutch consists of an electric oil pump, a solenoid valve and a clutch cylinder. When the ECU issues a command to drive the electric oil pump, the high-pressure oil produced by the electric oil pump is delivered to the clutch cylinder through the solenoid valve. The ECU controls the electric current of the solenoid valve to control the oil flow rate and oil channel change to realize the movement of the clutch cylinder piston, thereby completing the clutch action when the car starts and shifts. Compared with automatic transmission (AT) and continuously variable transmission (CVT) vehicles, ECUs with automatic clutch devices have advantages in terms of operating economy because their transmissions are also manual transmissions, so they have lower fuel consumption and manufacturing costs. Below AT and CVT. Of course, the convenience of car operation will be inferior to AT and CVT. After all, it is equipped with a manual transmission and still needs to be manually shifted.
1. Make sure the car starts smoothly The car is at a standstill before starting. If the engine and transmission are rigidly connected, once the gear is in gear, the car will suddenly rush forward due to the sudden connection of power. The huge inertia produced caused the engine speed to drop sharply and stall. If the clutch is used to temporarily disengage the engine and gearbox at the start, and then the clutch is gradually engaged, due to the phenomenon of slipping between the driving part and the driven part of the clutch, the torque transmitted by the clutch can be gradually increased from zero. The driving force of the car is gradually increasing, so that the car starts smoothly.
2.Easy to shift When the car is driving, different gearboxes are often used to adapt to changing driving conditions. If there is no clutch to temporarily disengage the engine from the gearbox, then the power transmission gear meshing in the gearbox will be difficult to separate because the load is not removed and the pressure between the meshing tooth surfaces is large. The other gear to be meshed will be difficult to mesh due to their different peripheral speeds. Even if it is forced into the meshing, it will produce a large impact on the tooth end, and it is easy to damage the machine. The clutch is used to temporarily separate the engine and gearbox and then shift gears. The original meshed pair of gears is removed due to load, and the pressure between the meshing surfaces is greatly reduced, which makes it easy to separate. For the other pair of gears to be meshed, since the moment of inertia of the driving gear is separated from the engine, the appropriate gear shifting action can make the circumferential speeds of the gears to be meshed equal or nearly equal, thereby avoiding or reducing the impact between the gears.
3. Prevent overloading of the transmission system During an emergency braking of a car, the wheels suddenly slow down sharply, and the drive train connected to the engine still maintains the original speed due to the rotating inertia. This often generates a moment of inertia in the drive train that is much greater than the engine torque, making the drive train Parts are easily damaged. Because the clutch transmits torque by friction, when the load in the drive train exceeds the torque that can be transmitted by the friction, the master and driven parts of the clutch will automatically slip, thus preventing the drive train from overloading. .
4. Reduce torsional vibration shock The working principle of a car engine determines the instability of its output torque. In the power stroke, the gas explosion in the combustion chamber generates a great impact torque, while in other strokes, the engine is dragged by inertia. Although the inertia of the engine’s rotating system can reduce torsional vibration, the remaining impact force still adversely affects the subsequent gearbox and transmission shaft. The damping spring (tangential distribution) in the clutch can significantly reduce the torsional vibration impact brought by the engine and prolong the life of the transmission gear.