| In order to satisfy the higher requirement of consumers and succeed in competitive market, plenty of bus manufactories attach more importance to the amenity standard of vehicle. When the engine runs at idle speed and bus is motionless,the bus loading home-produced diesel engine will occur acute vibration. Aim at the problem mentioned above,we carry on plenties of studies on how to lower the bus vibration in this paper. Fistly ,we evaluate the vibrating level of the bus ,through comparing with the vibration of bus which carry oversea's diesel engine, a rational vibrating evaluation criterion as the modified goal can be obtained. Secondly,by integrating theoretic study with experimental practice, we can detailedly analyze the reasons for acute bus vibration from three factors,which include Power-Assembly system, Power-Assembly suspension system and bus body. Form the result of analysis,it is an obvious fact that the Power-Assembly suspension system has not effective vibrating isolation ability. Thirdly,on the basis of the characteristic parameters of Power-Assemble system,the stiffness,site and orientation of suspension supporting block are able to be re-designed. Finally, subjective and objective appraisal of bus vibration can improve the modified effect satisfying. Passengers often complain about acute vibration When the engine runs at idle speed and bus is motionless.After testing the vibration of buses loading home-produced engine and inward engines,we find the weighting root-mean-square value of the fommer's vibrating acceleration is 10 times as high as the latter's .through integrating subjective evaluation with objective evaluation.we acquire that the vibrating control criterion of bus floorboard is 0.4 m /s 2and the vibrating control criterion of chair is 0.25m /s 2.In this paper,we are engaged in experimental and the theoretic study on the vibrating excitation of engine ,isolating effectivity of suspension system and dynamic characteristic of the bus body. the analytic results show as follow:1.the main vibrating energy of engine and bus body focus on 30Hz .2.the average vibrating intensity level of home-produced engine is 1.5 times as high as that of inward engine.3.The bus body don't occur modal vibration shapes at 30Hz.4.the transmissibility of engine suspension is too high,expecially, thetransmissibility of cross direction greater than 1. the basic reason which give rise to resonance vibration attributes to the inefficient isolation of engine suspension.we established the test-bed and the test facility in order to acquire the location of mass center and the processional moment of the power assembly. Find out the principal axis of inertia.on the basis of obtaining these parameters ,a new suspension system can be designed. This is to say, the stiffness, site and orientation of suspension supporting block are able to be re-designed. In the end ,the experiment prove that modified bus loading home-produced engine outmach the bus loading oversea's engine from average vibrating level angle. |
