| 摘要 |
An improved drive shaft is disclosed of the type used in a rotary fluid pressure device including an input-output shaft and a gerotor gear set having an externally toothed member which orbits and rotates within an internally toothed member. Both the input-output shaft and the externally toothed member define straight internal splines, and the drive shaft includes a set of crowned, involute external splines at each end thereof, in engagement with the respective straight internal splines. The crowned external splines are hobbed with a hob on which the cutter teeth have a pressure angle phi H greater than the primary pressure angle phi S of the crowned splines. The increased pressure angle phi H of the cutter teeth makes it possible to reduce the crown angle on the splines, while still maintaining the necessary clearance X between each external spline and the adjacent internal spline at any given axial distance Y along the external spline from the central plane. Reducing the crown angle makes it possible either to increase the length of the external splines for a given shank diameter, or to increase the shank diameter for a given spline length. In either case, the result is an increase in the torque carrying capacity of the shaft by a factor F, wherein F equals the ratio of sin phi H/sin phi S. |
