Dynamic Characteristics And Fatigue Life Of The Automobile Clutch Release Bearings

Automobile clutch release bearing is an important part of automobile power transmission system.In the vehicle driving process,clutch release bearing is the role of axial displacement with the aid of bearings connect or disconnect the power between the gearbox and engine transmission,smooth start,thus completing the car stop and shift operation.The release bearing is often used in high speed,strong vibration,high temperature,humidity and easy to pollution.Therefore,it is required that the release bearing has good strength and toughness,impact resistance,wear resistance and excellent contact fatigue performance.With the manipulation of the commercial vehicle high speed and heavy load transportation capacity,comfort and long life reliability requirements increase,in recent years the vehicle design and manufacturing level is rising,so the clutch bearing performance requirements are also getting higher and higher,and However,the performance of domestic heavy duty clutch has a large gap with foreign similar products.Therefore,it is of great theoretical significance and social economic value to establish the simulation model and to study on the dynamic characteristics and fatigue life of the clutch release bearing by using the modern design theory.In this paper,the modern design theory is used to study the dynamic performance,fatigue life test and analysis method,the contact stress and the film forming ability of the commercial vehicle release bearings.In order to improve the axial separation of the bearing capacity and prolong the service life and increase its reliability.The research work mainly from the following aspects:1.Development of load life simulation machine for heavy duty clutch release bearing.The structural dimensions,performance parameters and operating conditions of the clutch release bearings are quite different from those of the common angular contact ball bearings.There is a lack of uniform rating criteria for the bearing life test between the supplier and the automotive assembly plant.At present,the testing machine for clutch release bearing is mainly used for the development of small passenger car with light load and high speed.Therefore,the first research and development of a heavy-duty automobile clutch release bearing fatigue life testing machine.Maximum axial load of the testing machine: 14 kN;joint frequency: 0.25-2 Hz;separation stroke: 4-18 mm;test speed: 400-2800 rpm.Under normal test conditions,the calculation life of the spindle bearing can reach 100 thousand hours.2.Application of acoustic emission technique to study the characteristics of early fault signal of release bearing.It is very difficult to analyze the early fault signal of the bearing by vibration acceleration sensor.Noise testing is greatly influenced by the environment.In this paper,the technique of acoustic emission technique for the detection of incipient fault signal in the release bearing test is studied.The application of wavelet theory in frequency domain analysis of acoustic emission signal is studied.The experimental results show that acoustic emission technology is a highly sensitive nondestructive testing method,and the faults of the release bearings can be detected in the workshop production environment.When the acoustic emission technology is used to separate the bearings,the signal can be collected directly under the condition of the continuous running of the test machine.3.Experimental study on dynamic characteristics of bearing.The working state of the clutch release bearing is divided into static state,over state and stable rotation state.The results show that the vibration of the release bearing can be simplified to linear vibration.The design of the structure parameters of the release bearing has a direct influence on the natural frequency,the contact angle and the number of balls are related to the natural frequency of the bearing.With the increase of axial preload,the axial natural frequency increases and the axial amplitude decreases.4.The main factors affecting the fatigue life of the bearing are analyzed.In the process of clutch separation,the release bearing is mainly subjected to the axial force which is repeatedly and repeatedly separated from the static and rotating state.At the same time,it has to bear the radial force when the centrifugal force acts.Therefore,angular contact radial thrust ball bearings are widely used in automobile clutch release bearings.Therefore,it is necessary to study the influence of the separation force,rotational speed,the number of rolling balls and the clutch time on the fatigue life of the release bearing.The stress of the bearing under axial load is derived,and the fatigue life prediction model is established.The inner hole 57 mm push type release bearing fatigue life analysis shows that the great influence on the separation of bearing force separation,separation force for simulation of fatigue life of 5000 N is 5.6 times of 9000 N.In the joint time fixed under the prerequisite of the separation time is shorter,the fatigue life of separate thrust bearing is longer.When the bonding time is 2.5 s,the simulate life at separation time of 0.1 s is 3.86 times of the separation time 5S.