Study On Intensive Test Method For Automotive Transmissions Bench Based On Actual Load Spectrum

As key components of transmission system,the fatigue life of automobile transmission directly affects the performance of the entire transmission system.Transmission bench test is an important means assessment,evaluation and enhance its performance.The current transmission bench is still immature,commonly used fixed speed,fixed torque for standard steady test,the test load are usually standard spectrum of experience or learn from foreign load spectrum,the load spectrum is not a true reflection of the load information and the state of motion of domestic car on the actual road,resulting in poor experimental simulation accuracy.Second,the cycle of steady-state test is long,and gradually failing to meet the demand of adapting to the fierce market competition,an urgent need to explore ways to achieve acceleration test method for the transmission bench.This paper based on the actual business needs and deficiencies of the current steady-state transmission bench test,focusing on exploring methods to strengthen the load spectrum for transmission bench test based on the actual load spectrum,in order to achieve a shorter loading time,without losing realistic simulation accuracy,which helps reduce the experimental verification cycle for transmission,improving R & D efficiency for transmission,possessing strong theoretical significance and great engineering application value.Firstly,select the target measuring parameters including the torque,speed,oil temperature,the pedal state,strain and acceleration of the transmission,transmission synchronous acquisition system was built by KISTLER wheel force sensors and advanced eDAQ data acquisition device,in strict accordance with enterprise endurance test norms,actual load spectrum of transmission were fully collected on automobile Proving ground in western Chongqing.Next,select the torque signal of actual load spectrum of the transmission as the analysis target,completed the pre-processing and a variety of repetitive inspections of the load data.Based on information of the signal ratio and the pedal state,combined with their transmission parameters,the synchronous extraction for the actual gear load spectrum was completed.The statistical analysis on Torque signals was completed,including mathematical eigenvalue analysis,probability density analysis,systems correlation analysis,frequency spectral analysis,system coherence analysis to identify the target of useful load information in the time domain and frequency domain.And compared the characteristics of torque signal on different typical pavement.Then,the reference value matrix of torque load was obtained by the rainflow counting,equivalent one-dimensional load spectrum suitable for bench was got using Goodman law and the equivalent average method.On the one hand,the strengthening treatment of amplitude was implemented,used deleting small amplitude method and such damage concentration method to completion the acceleration of the initial torque load in amplitude strengthening,and then put forward the amplitude linear strengthen law including equal area method and equal damage method.On this basis,put forward the nonlinear strengthen.On the other hand,a certain degree of enhancement of the load spectrum was got with increasing the range of the frequency of torque load as well as reconstructing process back into the time domain with the Inverse Fourier transform in frequency strengthening method.The effect of load sequence effects on fatigue damage was briefly demonstrated by damage curve method.Eventually,through time-frequency domain damage analysis for the transmission output shaft and the gear,demonstrated the effectiveness of the strengthen method,the load spectrum equivalent associated with the original actual load spectrum was built between the amplitude strengthening and frequency strengthening methods.