Power unit for a vehicle

摘要

A power unit for a vehicle includes a buffering device provided on a final shaft parallel to a countershaft of a speed change gear. The buffering device includes a damper gear wheel supported for relative rotation on the final shaft, a lifter coupled against relative rotation but for relative movement in an axial direction on the final shaft and engaged by a cam provided on one face of the damper gear wheel, a spring retainer supported at a position on the final shaft spaced apart from the lifter, and a coil spring provided between the lifter and the spring retainer for biasing the lifter toward the damper gear wheel. The buffering device is disposed on the final shaft and positioned between a pair of imaginary planes, the pair of imaginary planes extending perpendicularly to an axial line of the idle shaft and passing opposite ends of the idle shaft.

主权项

1. A power unit for a vehicle, comprising:
a buffering device provided on a final shaft parallel to a countershaft of a speed change gear which is configured to change a speed resulting from rotational power inputted from an engine stepwise, wherein the buffering device includes:
a damper gear wheel supported for relative rotation on the final shaft,a lifter coupled against relative rotation but for relative movement in an axial direction on the final shaft and engaged by a cam provided on one face of the damper gear wheel,a spring retainer supported at a position on the final shaft spaced apart from the lifter, anda coil spring provided between the lifter and the spring retainer in such a manner as to exert spring force for biasing the lifter toward the damper gear wheel, wherein the power unit carries out changeover between a state where the rotational power in a forward direction from the countershaft is transmitted to the damper gear wheel and another state wherein the rotational power in a reverse direction from the countershaft is transmitted to the damper gear wheel through a reverse gear train including idle gear wheels supported for rotation on the countershaft and an idle shaft extending in parallel to the final shaft, wherein the buffering device is disposed on the final shaft and positioned between a pair of imaginary planes, the pair of imaginary planes extending perpendicularly to an axial line of the idle shaft and passing opposite ends of the idle shaft, wherein the spring retainer includes:
a coupling portion having a coupling end adjacent the lifter and spline coupled to the final shaft, the coupling portion being open to an opposite side to the lifter; anda flange portion connected to an outer periphery of an open end of the coupling portion and receiving the coil spring, wherein a positioning member engaging with the spring retainer from an opposite side of the spring retainer to the coil spring is mounted on the final shaft and disposed in the coupling portion, the positioning member is located closer to the lifter than the flange portion is, and the entire positioning member is located in front of the entire flange portion in a direction that is along the axial direction of the final shaft and faces the lifter, wherein a bearing member at least partially overlaps with the coupling portion as viewed in a direction perpendicular to an axial line of the final shaft, and is interposed between the final shaft and a shaft supporting member which supports the final shaft for rotation thereon, wherein the bearing member is a needle bearing, wherein a rotary shaft is connected at one end thereof coaxially against rotation at an end of the countershaft, wherein the buffering device and a reverse gear train are disposed within a width of the rotary shaft, and wherein a retaining ring is disposed in the coupling portion and mounted on an outer periphery of the final shaft, and the retaining ring serves as a positioning member for stopping the spring retainer and the final shaft.