Key Technology Research On Load Spectrum Compilation For Commercial Vehicle Transmission

Transmission as the core component of automobile power transmission system,its reliability is related to the reliability and stability of the vehicle,based on the transmission load spectrum related to user actual use condition in the transmission reliability prediction plays a vital role.At present,the domestic in passenger car transmission load spectrum compiling ways have formed a set of relatively complete specification,due to the working condition of commercial vehicles than passenger cars is more complex,the transmission is more prone to failure,therefore,transmission load spectrum compiling load spectrum of the test system,the load spectrum statistical counting method and the load spectrum extrapolation related research on the key techniques is necessary,for the commercial vehicle transmission reliability and durability is of great importance.In this paper,a kind of commercial vehicle transmission as the research object,through the analysis of the load of transmission bench test required signals and the structure characteristics of the test vehicle transmission system,the load spectrum of measuring point and target signal are selected and transmission load spectrum test system is set up,according to the test vehicles used the typical working condition,the measuring point,target test road mileage,speed and the principle of gear selection are determined.Signal analysis and processing,probability theory and mathematical statistics and the theory of fatigue damage analysis are applied to dealing with original signal and sample selection of random load,according to the gear synchronous signal,different traffic load of each gear are extracted,four points rain flow counting method is used to count the load of each gear,and then choosing the rain flow matrix nonparametric extrapolation,rain flow matrix of each gear load frequency and the maximum load are extrapolated,based on the principles of damage,the rain flow matrix is compiled to eight levels program load spectrum applied to indoor bench test and programmed load spectrum is regarded as the load power of transmission simulation model.Damage and fatigue life of transmission gear parts are counted,forming a relatively perfect transmission load spectrum test,preparation and application of research methods,other parts for car load spectrum compiling is of certain reference value.According to the structural characteristics of commercial vehicle transmission,the transmission shaft torque,rotation speed,corresponding gear signal,and the vibration acceleration signal of the road condition information are selected as the test signal.the transmission load spectrum test system taking the torque-speed wireless telemetry system composed of node TQ201 H and wireless gateway BS903 and the YMC9232 high performance dynamic data acquisition instrument as the core is set up.Based on the typical conditions associated with users,the road load spectrum test collection scheme is developed and the road load spectrum of a commercial vehicle transmission is collected.According to the related theory of signal analysis and processing,through MATLAB and Ncode-Glyphworks data processing software,the measured random load time history is dealt with detrending,eliminating singularities and time and frequency calibration analysis.Combined with principle of maximum damage,the sample load of different conditions can be confirmed.At the same time,the load information of each gear under different working conditions is extracted with reference to the gear information corresponding to dynamic load.By using the four-point rain flow counting method,the load frequency statistics of each gear under different working conditions were calculated.The non-parametric extrapolation of the rain flow matrix for each load rain flow count in the form of "From-To" is carried out by Epanechnikov kernel function.The finite sample load cycle is extrapolated to the full life cycle,so that the equivalent load of the transmission's total endurance cycle length is obtained.According to the result of each gear load extrapolation,the each gear load amplitude logarithmic cumulative frequency curve is achieved and rain flow matrix extrapolation load continuous cumulative frequency curve is converted eight level program spectrum in accordance with principle of equal damage conversion.Considering the loading cycle and loading sequence,a complete test load spectrum was synthesized for each file in three different road conditions.In order to verify the load spectrum,through Romax Designer simulation software,the load spectrums regarded as the power flow of transmission parallel axis model calculate the damage and predict the life of the transmission gears and bearings.