Patent ID: 6422368
Filing Date: 2002-07-23
Classification: F16D

Abstract:
A hydraulic power transmission joint adapted to be interposed between an input shaft and an output shaft that are rotatable relative to each other, to transmit torque as a function of the rotational-speed difference between said input and output shafts, said hydraulic power transmission joint comprising:a housing to be coupled to said input shaft and having a cam face formed on its inner side surface; a rotor to be coupled to said output shaft and being rotatably accommodated in said housing, said rotor having a plurality of axially extending plunger chambers; a plurality of plungers each being reciprocatively accommodated in each of said plurality of plunger chambers under a biasing force of a return spring, said plurality of plungers being operated by said cam face upon the relative rotations of said housing and said rotor; a discharge hole formed in said rotor and opening to said plurality of plunger chambers; a valve block coupled to said rotor for being rotated jointly; an orifice formed in said valve block for generating a flow resistance under the action of flow of oil discharged by operations of said plurality of plungers; and a drain mechanism provided in said valve block, said drain mechanism serving, when a predetermined temperature is reached, to open a drain hole to allow oil to flow from a high-pressure side into a low-pressure side to thereby cancel a transmission of torque, said drain mechanism serving, until said predetermined temperature is reached, to regulate the opening of said drain hole to limit a transmission torque to a certain value irrespective of increase in the rotational-speed difference; wherein said drain mechanism includes a drain pin slidably accommodated in a drain plug, and a limiter pin received in a limiter plug disposed in abutment against said drain plug for opening and closing a communication hole that leads to said drain pin, with one end turn portion of said return spring being press fitted into the interior of said drain pin, and with the other end turn portion being press fitted into the interior of said limiter plug, to thereby rotationally position said drain pin.