| The wet clutch is a key component of the transmission system of heavy-duty vehicles,and when it is in a separate state,the relative movement between the main and slave components causes the lubricating oil liquid in the friction pair gap to produce viscous shear torque,which is the drag torque.Drag torque is an inherent disadvantage of wet clutches themselves,reducing clutch transmission efficiency and fuel economy.Based on this background,this paper studies the drag torque problem of clutch in order to reduce the drag torque of the displacement as much as possible in terms of design,which has important theoretical research significance for improving the efficiency of clutch.In order to solve this problem,Firstly,the internal fluid flow of the single-friction pair is studied,and the simulation model of the single-friction pair is established according to the basic control equation of the flow field and the multiphase flow model.The influence of different working conditions on the drag torque and power loss were analyzed,and the simulation rationality was verified.Secondly,the finite element models of friction pairs of circumferential groove,radial groove and composite groove were established using the verified model,and the effects of different groove forms and different groove structural parameters on the internal flow field and drag torque and power loss were analyzed.Thirdly,according to the simulation and analysis results above,an improvement scheme is proposed for the drag torque problem of composite groove friction disc,and combined with multi-island genetic algorithm,the working condition parameters and groove structure parameters are taken as the optimization parameters,and the drag torque is the goal to carry out the structural optimization design.Finally,the optimized results are experimentally verified.The results show that the loss value of drag torque and drag power is related to the separation gap and inlet flow,and the smaller the separation gap and the larger the inlet flow,the greater the loss of drag torque and drag power.The flow characteristics of the internal flow field of the friction pair of different groove shapes are different.Radial grooves and composite grooves have a lot of pressure on the groove sidewall on the opposite side of the direction of rotation.The groove sidewall pressure on the same side as the direction of rotation is low because the effect of the rotational tangential force results in relatively little oil.The circumferential groove oil flow between the sheets is only affected by the circumferential loss,and the pressure distribution of the circumferential groove with the same radius is relatively uniform.Increasing the number of grooves,changing the depth of the groove,and tilting the groove at a certain angle can enhance the flow of oil,and the change of groove structural parameters will change the drag torque and the drag power loss value,so the selection of appropriate groove parameters can effectively reduce the drag torque and drag power loss.Through the structural optimization design of the clutch,the flow of oil can be enhanced,the oil film can be broken in advance,and the drag torque and drag power loss can be effectively reduced.In the given full operating speed range,the simulation and experimental comparison of the optimized front and rear clutches show that the maximum relative error between simulation and experiment is 5.2%.Compared with the optimized front friction disc,the maximum drag torque of the optimized friction disc is reduced by 15.24%,and the drag torque and drag power loss of the optimized friction plate are lower than that of the optimized front friction plate under the full speed range. |
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