Analysis And Optim Ization Research On BOSCH Starter Solenoid Switch

The solenoid switch,as one of the most important components of starter,controls the engagement of the starter’s pinion and the engine’s ring gear as well as the switch on and switch off the main circuit of the starter’s motor.Supporting the latter function is electrocontact structure of the solenoid switch.The investigation prove there is a risk of contact welding in the electrocontact which is one of the important reasons limiting the starter’s lifetime.Basing on the current study,a deep research was done on the electrocontact of the solenoid switch of the BOSCH starter in two ways:analysis and optimization of the contact material;vibration analysis and structure optimization of the electrocontact.The most important research findings as below:1)Regarding analysis and optimization of the contact material,the anti-welding performance of pure Cu and several Cu alloys was tested.Basing on the test results,the anti-welding performance decrease in the order of CuTe,CuW30(or Cu/CuW30),Cu,CuA1203,Cu/Ni/TiN,CuCr1Zr,Cu/TiN and CuNi1Si under our test conditions and also that the CuTe-CuTe pair have the best welding resistance ability in all the contact pairs,including the contact pairs with same electrode materials and with dissimilar electrode materials.Now this new research result was used in BOSCH series commercial vehicle starter,which improved the solenoid switch quality.2)Regarding vibration analysis and structure optimization of the electrocontact,the sensitivities of the main parameters of the solenoid switch and found that the stiffness of the disc spring is the most important parameter influencing the vibration of the electrocontact.So the wave spring was used to replace the disc spring and optimized the structure of the solenoid.Basing on the simulation results of the finite element analysis of LS-Dyna,It was found that the wave spring damp the vibration of the electrocontact significantly.And this optimized structure will reduce the electrical arc and also improve the anti-welding performance which is also supported by the test results of the sample of the new structure.Now the new structure design was applied for the innovation patent,and the patent was awarded.