Four-gear transmission electric drive axle system

The invention relates to a four-gear transmission electric drive axle system which is suitable for a pure electric drive heavy commercial truck and comprises a first motor, a first gear shifting mechanism, a planetary gear train and a differential mechanism. Compared with the prior art, under the condition that the number of gears is guaranteed, the structure is simple, the number of shaft systems is small, gear power flow planning is smoother, the number of transmission stages is small, high gears are all in three-stage transmission, the design torque capacity is large, power control is convenient, the design scheme is more modularized, the low-gear large-torque requirement and the high-gear high-speed requirement of the whole vehicle can be considered, and the whole vehicle can be widely applied. And meanwhile, the motor is in the optimal efficiency rotating speed interval. 本发明涉及一种四挡传动电驱桥系统，适用于纯电驱动的重型商用卡车，该系统包括第一电机、第一换挡机构、行星轮系及差速器；与现有技术相比，本发明在保证挡位数的情况下，构型简单，轴系较少，挡位功率流规划更加顺畅，且传动级数少，高挡位均为三级传动，设计扭矩容量大，动力控制方便，设