Measurements And Analysis On Torsional Vibration Of Camshaft In Valve Train

Valve train is an important component of the engine, through which the valve timing effectsdirectly affect the performance of the whole machine. With the variable valve technologypopularization, accurate valve timing becomes more and more important. The valve timing dependsmainly on the motion characteristics of camshaft. Besides the influence of cam profile, the torsionalvibration of camshaft also has important effects. On the basis of the extensive study referring thedomestic and foreign literature about the torsional vibration of camshaft, and combining with theactual situation, based on the theory of temporal pulse method, using the experimental method tomeasuring and calculating the torsional vibration of the camshaft. Combined with the dynamiccharacteristics of valve train, study the relationship between the torsional vibration of camshaft andvalve timing. The main research work can be summarized as follows:1. Introduce the torsional vibration of the camshaft measurement test and the valve traindynamic test. Introduce the specific composition and working principle, and the dataacquisition system.2. Apply the VC++language and Labview software to program, and succeed in collecting andsignal processing of acceleration, angle, torque signal. And use Matlab for splineinterpolation to the acquisition of different frequency signal and calculate the torsionalvibration. Offer conditions and data basis for the simulation analysis work. According tothe need of experiment introduced in this paper how to collect the detailed data.3. Based on the principle of pulse timing measurement, change of measurement method, useof PCI data acquisition and the sensor which can output angle signal for measurement andanalysis. Under the different speed, collecting the both sides of the cam shaft angle signal,as well as other torque, acceleration signal. Screen and calculate the collected test data.Then analyze it, we found that along with the camshaft speed, the torsional angle graduallyimproved, but not beyond the limited scope. Analysis the contact-stress of cam shaft andgets the position of the maximum. And analysis the speed of camshaft. According to theexperimental results of the torsion angle of the harmonic analysis to discuss therelationship between the amplitude of the torsion angle and the speed of camshaft.Compare with the result of the valve train dynamic test, analyze torsional vibration impacton valve timing.4. Using the simulation method to structure the valve train model. Analyze the torsionalvibration of the camshaft and the camshaft free modal. The result show that the cam shaft critical speed under forced vibration is far beyond the working speed range. Respectivelyon two conditions that taking account of torsional vibration and negligible torsionalvibration for dynamics analysis. On this basis, further analysis of the impact of thecamshaft torsional vibration to the valve train timing.