Optimization Research On Vibration Characteristics Of Diesel Locomotive Isolated Cab

In today’s highly developed electrification,diesel locomotives still occupy a large proportion of the total number of railway locomotives in china.The diesel locomotive equipped with the high-power diesel generator set will vibrate violently during the operation.In addition,with the increase of the running speed of the locomotive,the low-frequency excitation from the track will also increase,and the vibration of the vehicle body caused by the two excitations will be transmitted to the cab,causing it vibrate.The survey shows that,restricted by the operating conditions,the locomotive drivers and passengers generally stay in the cab for a long time,usually more than eight hours.And long-time work in a whole-body vibration environment is more than twice as likely to suffer from severe lumbar and cervical spondylosis.Therefore,it is necessary to set reasonable suspension parameters of the cab to reduce the vibration of the cab under external excitation,and to improve the comfort of the driver and passengers and the service life of the equipment.Some researches are carried out in this thesis under this background:Firstly,according to the diesel power analysis and balance analysis,the excitation generated in the working process of a diesel engine is theoretically deduced,and the basic parameters of the diesel engine are substituted to obtain that the average value of the theoretical overturning torque of the diesel generator set is 4.6×10~4 N·m,the excitation frequency is 16.67 Hz.In addition,the theory of load inversion is introduced,and a dynamic tensile test of T-shaped specimen is designed to verify the feasibility of the inversion theory.Through the self load test of a diesel locomotive,the strain at the mounting seat of the diesel generator set is collected.Combined with the inversion theory,the average inversion overturning moment of the diesel generator set is 4.8×10~4 N·m,the excitation frequency is16.67 Hz.The inversion excitation of diesel generator set is consistent with the theoretical excitation mean and frequency,and it is determined that the inversion excitation of diesel generator set is in line with reality.Secondly,the dynamic model of the locomotive is established to analyze the vibration characteristics of the cab under the combined action of the diesel generator set excitation,the track excitation and the two excitations.The research results show that the longitudinal and lateral directions of the cab are dominated by rigid body vibration,and the vertical direction is the coupling of rigid body vibration and structural vibration,and the main frequency of vibration in the three directions is 16.67 Hz.The vibration of the cab under the track excitation is dominated by low frequency vibration(below 10 Hz).The vibration of the cab caused by the driving of the locomotive mainly comes from the excitation of the diesel generator set,followed by the track excitation,but the track excitation is also a part that cannot be ignored.Finally,the stability index is used as the basis for parameter optimization of the cab suspension system under the combined action of diesel generator set excitation and track excitation.The rear-end rubber shaft,front-end steel circular spring stiffness and front-end shock absorber damping were optimized respectively,the optimization factors of the suspension parameters of the cab were determined,and the optimization results were evaluated.After optimization,under the combined action of diesel generator set excitation and track excitation,the lateral and vertical stability indicators of the driver’s seat foundation can reach the excellent level.The maximum vibration acceleration response in three directions on the seat foundation has also been greatly improved,and the vertical optimization effect is the most obvious.