| The power-shift steering transmission(PSST)has become one of the key technica l characteristics of modern tracked vehicle.Most of the power loss of the PSST is transmitted to the transmission mechanism and the surrounding cabin in the form of heat energy.As the power of the tracked vehicle diesel engine increases,the heat of the transmission increases gradually,a series of problems caused by the heat can't be ignored.In this paper,the PSST of tracked vehicle and its shift clutch are studied,and the power loss and thermal characteristics under direct driving condition are discussed.Firstly,an improved model of clutch drag torque and loss considering the effect of the dynamic variation of friction gap is established,which lays the foundation for the calculation of power loss in clutch separation phase.Then,the temperature rise characteristic model of wet clutch system is established,and the friction loss of clutch system is discussed.And the power transmission loss model of the PSST is established,and the power loss characteristics are summarized from the point of view of the working condition.Finally,the direct drive thermal characteristics of the PSST are constructed,the thermal characteristics of the main components are analyzed.The main work is as follows:The influence of the inclination of friction element and the gap shrinkage under the high speed difference on the drag torque of the wet clutch is studied and compared with the traditional and the gap non-uniform model.Combined with the results of the wet multi-clutc h clutch drag loss test,the improved model of clutch drag torque and loss considering the effect of the dynamic variation of friction gap is established.The effect of dynamic variation of gap in the range of full speed difference is analyzed,and the evaluation parameter system with drag torque is proposed.Based on the hydraulic circuit in the clutch system and the analysis of heat transfer node,the temperature rise heat resistance model of the clutch system is constructed.The model is verified by the wet clutch test.The relationship between the friction pair and oil temperature rise characteristics and the cooling impact factors of wet clutch system is simulated and analyzed.The main and total power loss models of the PSST are summarized and established.The total power loss model of the PSST is verified by the test,and the total power loss characteristics and influencing factors of the PSST,the transmission efficiency of each gear and the proportion of main heat source of the power loss are analyzed.For the five different areas of vehicle traffic conditions,combined with the using proportion of the gear,the tracked vehicle speed shift calculation model is established,the statistical tracked vehicle gear use characteristics and driving condition for the five areas are obtained,the gear use and shift frequency characteristics with the difference between of road conditions are analyzed.Based on the temperature rise characteristic model of the clutch system and the two lumped parameter methods of the hydraulic and the box,the thermal characteristics of the PSST are constructed.The thermal characteristics of the main components of the PSST are analyzed according to the vehicle driving conditions in different regions.The the design of factors for the cooling and lubrication system are provided with scientific and model basis. |
PDF Full Text Request