Study On Coupled Vibration Of Diesel Locomotive Between Diesel And Carbody

Though high electrification leads to large use of electric locomotive nowadays, diesel locomotive still possess some advantages such as high mobility, low one-time cost and quick start which electric locomotive doesn’t have. For this reason, diesel locomotive is still mainly used worldwide. In the beginning, because of low speed and power of diesel locomotive, vibration control of carbody was undemanding. However, with the increase of speed and diesel power, vibration problems of diesel locomotive have been given attention. Particularly, work environment problem of diesel locomotive cab has become one of the most import problems during diesel locomotive design.First of all, on the basis of the proof of the structural strength of4400horsepower shunting locomotive, the excitation forces of12V265diesel of4400horsepower shunting locomotive in its working condition were analyzed theoretically including gas force, Inertia force, inertia moment, overturn moment etc. Diesel vibration test showed that the excitation force on the supports of diesel and generator is consisted of many periodic forces of diesel frequency and its multiple frequencies. For12V265diesel, under the working condition of1000cycles per minute, the excitation force on the support will be8.33Hz,16.67Hz,25Hz,33.33Hz etc.After being aware of the characteristics of excitation force of12V265diesel, in order to know how the phase and amplitude of excitation force will influence the vibration of cab,4harmonic cases for lateral direction and vertical direction were respectively set. Result showed that when all of the6supports have the same phase and the maximum amplitude the cab will vibrate with the greatest amplitude. This loading method will be used in the following analysis.4400horsepower shunting locomotive was equipped an isolated cab which was connected to the underframe by elastic elements. For minimizing the vibration amplitude of cab seat during working condition, on the basis of modal superposition, the maximum normalized amplitude was put forward in this article and used to assess the vibration of cab. By optimizing the stiffness of cab rubber pivot, a best pivot was got which made the maximum normalized amplitude of cab seat minimum.Since elastic elements can be added between cab and underframe or between diesel and underframe, a damping structure of two levels for diesel locomotive was designed. Simplified models of two-level damping structure and one-level damping structure (isolated cab) were built in Simulink and damping performance of these two structures were compared. Result showed that for some periodic continuous excitation forces such as the excitation force from diesel, two-level damping structure can reduce the amplitude of cab better; for some random abrupt excitation forces, one-level damping structure can reduce the amplitude of cab more quickly.