Study On Fatigue And High-speed Characteristics Of Automotive Engine Oil-pump Narrow-width Chain

As the development of the chain's product and technology, the auto engine is adopting timing chain, lubricating oil pump chain, trunnion shaft chain and share rail chain, and so on. The failure mechanism and design theory change completely. Meanwhile, requirement for chain is strong wear quality, as well as the high-speed multi-impact and speed, load fluctuant characteristics has formed a technical difficulty and new ideas of the chain industry."Study on fatigue and high-speed characteristics of automotive engine oil-pump narrow-width chain"is supported by National Technology Creating Foundation of china for medium and small scientific enterprise(No.01C2621330 0872)(High strength automotive chains). by analyzing the fatigue and high-speed characteristics of automotive engine oil-pump chains in domestic and overseas, the fatigue and high-speed characteristics of automotive engine oil-pump chains are researched.Automotive engine oil-pump chain 06BN-1 is narrower than the same specification o6BT-1, so general named for narrow-width chain. At the same work condition, 06BN-1 hinge pairs endure higher stress, so its wear fatigue and impact fatigue damage probability is bigger than o6BT-1's But for its narrow breadth and light weight, these can satisfy the light-weight demand of engine. It is significant to study on fatigue and high-speed characteristics of automotive chain 06BN-1.The fatigue lifetime distribution rule of automotive engine chain 06BN-1Ⅰand 06BN-1Ⅱ. The result shows that the fatigue lifetime distribution rule of automotive chain 06BN-1 is Weibull distribution of two parameters in a test condition of high stress. Form parameter and measure parameter augment with load accelerating. Through bunching fatigue test, R—S—N curves of different reliability according to load level and fatigue lifetime are founded, and fatigue strength of automotive chain 06BT under different reliability is received, at the same time, sample test projects of fatigue lifetime reliability test are offered on basis of the fatigue lifetime distribution rule of automotive engine chain06BN-1. Sample test by accelerating test and sampling test under normal load of automotive engine oil-pump chain 06BN-1 are studied. Sampling test by accelerating test at 0.30Q and 0.33Q of 06BN-1Ⅰare respectively timesaving 14% and 25% than sampling test under normal load at 0.25Q. Sampling test by accelerating test at 0.30Q and 0.33Q of 06BN-1Ⅱare respectively timesaving 17% and 25% than sampling test under normal load at 0.25Q. Sampling test by accelerating test can save more test time and reducing more test cost than sampling test under normal load, and work efficiency can be increased. Considering invalidation of automotive engine oil-pump chain 06BN-1, over load mode level is choosed by 0.30Q~0.33Q.The wear failure mechanism has been studied in this paper, through engine assemble test and table test and road test of chains. In the tests, in order to deeply study the wear failure mechanism, we adopted measuring the wear-elongation of chain, surface hardness of parts, and microscopic analysis of wear surface by scanning electron microscope. The results show that the main wear mechanism of high-speed automotive chain is fatigue wear and fretting wear, following galling wear, adherence wear. Ensuring sufficient strength and plasticity of roller, as well as adopting suitable shaping technique are the effective method to increase its resistance to multi-impact. It can be seen that the surfaces of pin and bush have occurred cycle-soften phenomenon. Roller surface has occurred cycle-harden phenomenon because of plastic change and process harden. It is attributed to the speed and load performance that produce many frictional heats among the pins and bushes.Through the study of the influencing factors for the working conditions and wear failure mechanism, the methods have been put forward to enhance the resistance to wear and resistance to fatigue. These methods are Suitable selection of the materials of chain parts and some suitable strengthening technique.These are the key design and manufacturing techniques of automotive chain.Fretting mechanism is studied in this paper.Because of the automotive chain's high velocity, changeable speed's repetitious concussion, the copulated surfaces of the two interfered parts which are connected by the pin and the outer link plate hole, the sleeve and the inner link plate hole, tiny abrasion occur on the pins. Followed by the tiny abrasion's strengthen gradually, the intensity between the pin and outer link plate hole, sleeve and inner link plate hole decreased. When it reachs on some degree, the two copulated surfaces begin to become flexible and which would resulted in the automotive chain's invalidation.This study results can verify that fretting wear exists during automotive engine oil-pump chain working. Some measures to the protection for fretting damage of automotive engine chain are discussed through studying on the cause of fretting. These are measures that enhance fastness degree of chain links and interference conjunction degree and tangent area of bush and inner link hole.At present, the part of the research fruit of the dissertation has been spread and applied in the fields of the chains and automotive engine and so on, and brings favorable economic and social benefit for correlated fields.