Patent ID: 9102226
Filing Date: 2015-08-11
Classification: B60K,B60L,F16D,F16H,Y02T

Abstract:
1. A motor drive apparatus for a vehicle comprising: an electric motor; a normally meshing type transmission comprising first and second shafts extending parallel to each other, the first shaft being connected to the electric motor, a plurality of gear trains each provided between the first and second shafts and having different gear ratios from each other, each of the gear trains comprising an input gear mounted on an outer periphery of the first shaft so as to rotate together with the first shaft, an output gear meshing with the input gear and mounted on an outer periphery of the second shaft so as to be rotatable relative to the second shaft, and a two-way roller clutch disposed between the output gear and the second shaft and comprising rollers and a retainer retaining the rollers and configured to be engaged and disengaged by rotating the respective retainers, wherein the first and second shafts are configured to be coupled to each other through any one of the gear trains of which the two-way roller clutch is engaged, and a speed changing actuator assembly for engaging any selected one of the two-way roller clutches by rotating the retainer of the selected one of the two-way roller clutches, thereby coupling the first and second shafts through the gear train including the selected one of the two-way roller clutches; and a differential gear assembly coupled to the second shaft for distributing power transmitted from the electric motor through the transmission to vehicle wheels, wherein the two-way roller clutches each comprise an inner ring mounted between the second shaft and the output gear of the corresponding gear train and rotationally fixed to the second shaft, wherein a cylindrical surface is formed on one of a radially outer periphery of the inner ring and a radially inner periphery of the gear of the gear train such that the one of the inner ring and the gear of the gear train that has the cylindrical surface formed thereon constitutes a cylindrical surface member, and cam surfaces are formed on the other of the radially outer periphery of the inner ring and the radially inner periphery of the gear of the gear train such that the one of the inner ring and the gear of the gear train that has the cam surfaces formed thereon constitutes a cam surfaces member, thereby defining wedge-shaped spaces between the cylindrical surface and the respective cam surfaces, each wedge-shaped space narrowing toward its circumferential ends, wherein said rollers are disposed between the cylindrical surface and the respective cam surfaces, and wherein said retainer is mounted between the inner ring and the output gear of the gear train, wherein the two-way roller clutch further comprises a switch spring mounted between the retainer and one of the inner ring and the output gear of the gear train that is formed with the cam surfaces for elastically retaining the retainer in a neutral position where the rollers are in engagement with neither the cylindrical surface nor the cam surfaces, wherein the speed changing actuator assembly comprises friction plates each rotationally fixed to the retainer of one of the two-way roller clutches and movable toward one side of one of the cylindrical surface members, elastic members each biasing one of the friction plates away from said one of the cylindrical surface members, a control ring slidably supported on said one of the first and second shafts and movable toward any one of the cylindrical surface members, thereby pressing the corresponding friction plate against the one side of said one of the cylindrical surface members, a sleeve rotatably supported around the control ring, and a shift mechanism for shifting the sleeve toward any one of the cylindrical surface members, wherein the motor drive apparatus further comprises an electronic control unit for controlling the electric motor and the speed changing actuator assembly, said electronic control unit being configured, upon receiving a command to change gears, to actuate the speed changing actuator assembly to move one of the friction plates away from the corresponding one of the cylindrical surface members, repeatedly determine, after the speed changing actuator assembly has been actuated, whether the one of the friction plates has actually moved away from the one of the cylindrical surface members, maintain a current torque of the electric motor after the speed changing actuator assembly has been actuated, until the one of the friction plates has actually moved away from the one of the cylindrical surface members, and if the electronic control unit determines that the one of the friction plates has actually moved away from the one of the cylindrical surface members, the electronic control unit is configured to change the torque of the electric motor to a level which allows disengagement of the two-way roller clutch corresponding to said one of the friction plates, and after the two-way roller clutch corresponding to said one of the friction plates has been disengaged, the electronic control unit controls the speed changing actuator assembly to engage another one of the two-way roller clutches.