With the rapid development of national economy, the output of automobiles has increased year by year, reaching 7.2 million in 2006. There are more and more cars in China, and their models are becoming more and more complicated. Especially with the rapid development of high technology and the wide application of some new technologies and materials in automobiles, it is more difficult to diagnose and eliminate automobile faults. This paper mainly introduces the fault analysis and maintenance methods of automobile clutch. Clutch is an important assembly necessary for manual transmission vehicles. Without the clutch, the car will not start and it is difficult to shift gears. In the process of using the car, the clutch will inevitably have such and such faults, which will directly affect the normal operation of the car. Nowadays, cars are rapidly entering families, and the degree of privatization of cars has increased. Car failures will affect everyone. It is of great practical significance to analyze and study the phenomena and causes of clutch failure, and explore the troubleshooting methods and maintenance techniques of clutch failure. This paper focuses on the clutch failure of Beijing Hyundai Motor Co., Ltd., so as to correctly understand the clutch failure and better use and maintain the clutch.

The clutch is installed between the engine and the transmission to separate or engage the power connection between the front and rear parts. Its function is: 1) to make the car start smoothly;

Multi-disc clutch, the pioneer of disc clutch used today, appeared after 1925. The main advantage of multi-disc clutch is that the clutch is engaged smoothly and there is no impact when it is started automatically. From the late 1920s to 1930s, only engineering vehicles, racing cars and high-powered cars used multi-disc clutches. With years of practical experience and technical improvement, people gradually tend to single-chip dry friction clutch, because it has the advantages of small moment of inertia of driven parts, good heat dissipation, simple structure, convenient adjustment, compact volume and complete separation. And some structural measures have been taken to achieve smooth joint, so now large, medium and small models are widely used. Now the single-chip dry friction clutch has been quite perfect in structural design. The driven plate with axial elasticity is adopted to improve the riding comfort when the clutch is engaged. The clutch driven plate assembly is equipped with a torsional damper, which can prevent the torsional vibration of the transmission system and reduce the noise and dynamic load of the transmission system. With the improvement of people's requirements for automobile comfort, the clutch is constantly improved on the original basis, and more and more dual-mass flywheel torsional dampers are applied to passenger cars, which can effectively reduce the noise of transmission system.

There are several kinds of automobile clutches, such as friction clutch, hydraulic coupling and electromagnetic clutch. The hydraulic coupling transmits torque through working fluid (oil), and the shell is connected with the pump wheel as a whole, which is the driving part; The turbine is opposite to the pump wheel and is a driven part. When the rotating speed of the pump impeller is low, the turbine cannot be driven, and the driving part and the driven part are separated. With the increase of pump impeller speed, the turbine is driven, and the driving part and the driven part are in a joint state.

The electromagnetic clutch controls the engagement and disengagement of the clutch by turning on and off the coil. If the magnetic powder is placed between the driving and driven parts, the meshing force between them can be enhanced. This kind of clutch is called magnetic powder electromagnetic clutch.

At present, the clutch matching with manual gearbox is mostly dry friction clutch, which can be divided into single disc, double disc and multi-disc according to the number of driven discs. Friction clutches can be divided into wet clutches and dry clutches.

Working principle of clutch

The working principle of the clutch: The driving part and the driven part of the clutch use the friction between the contact surfaces, or use liquid as the transmission medium (hydraulic coupling) or use magnetic transmission (electromagnetic clutch) to transmit torque, so that they are temporarily separated and gradually engaged, and the two parts are allowed to rotate with each other during the transmission process. At present, the friction clutch pressed by spring is widely used in automobiles.

The engine flywheel is the driving part of the clutch. The driven disc with friction plate and the driven disc hub are connected with the driven shaft (transmission drive shaft) through sliding splines. The compression spring compresses the driven disc on the end face of the flywheel. The torque of the engine is transmitted to the driven disk through the friction between the flywheel and the driven disk, and then the wheels are driven through the driven shaft and a series of components in the transmission system. The greater the pressure of the spring, the greater the torque that the clutch can transmit.

When the clutch release bearing is short of oil, it will make a squeaking sound. At this point, the release bearing should be oiled or replaced.

When the release lever (or the release finger end of diaphragm spring) is not in the same plane, it is easy to break the damping spring, and it will slip continuously when starting, causing vibration. In addition, the same phenomenon will occur when the clutch spring breaks and the elastic force becomes smaller. The elastic force of the return spring of the release lever is weakened, which will lead to poor return of the clutch release bearing, resulting in incomplete clutch separation and abnormal noise. At this time, the height of the release lever should be adjusted evenly and the spring should be replaced.

The spline of the driven disc hub or clutch driven shaft is worn, so the driven disc or clutch driven shaft should be replaced.

The shaft journals of clutch, transmission and engine crankshaft are misaligned and should be aligned.

Noise caused by damage of front guide bearing (sleeve). As long as the clutch is disengaged, there will be noise, and once the clutch is engaged, there will be no noise. This kind of noise is sometimes misunderstood as the failure of the release bearing, so pay attention to distinguish it. Improper installation of the transmission often puts extra stress on the guide bearing, which will damage the clutch after several uses and soon lead to noise.

Sharp noise will appear after any type of release bearing fails. If the release bearing is faulty, the noise will increase with the increase of clutch pedal force. If noise occurs after the clutch is disengaged, it means that the front guide bearing is faulty. The noise after the clutch is fully engaged will come from the transmission. Insufficient preload of clutch control system bearings can also cause noise.

If the transmission is in neutral and the engine is running, you can hear a "click" sound in the chamber, which is the noise in the transmission. It can be said that this is the noise caused by the torsional vibration of the transmission system in the transmission due to the excitation of the engine. This is closely related to the structural performance change of the torsional damper in the clutch driven plate.