To provide a hydraulic continuously variable transmission which solves the problem that conventionally, a notch is arranged at the port end of a valve plate so as to reduce noise, if press molding is adopted to lower the cost, a notch groove at the port end is rounded in its tip so that the delicate change of an opening area couldn't be produced and the noise reducing effect isn't sufficient, and if a peripheral groove is formed on the valve plate to retain a neutral position, the press molding process is increased and the cost is also increased.
An opening width of both ends of at least one of the following ports, plunger port 21f defined on a sliding end face 21d of a plunger block 21b and kidney ports 41a, 41b defined on a valve plate 41, is changed in circumferential direction so as to delicately change the overlapping amount whose border is the side parts of both ports, according to a rotation of the plunger port. On the sliding end face, within an inside/outside diameter area of the plunger port, a circumferential groove 62 which communicates between the plunger ports is provided.
MOCHIZUKI YASUHISA
SASAHARA KENGO
JPH11182411A | 1999-07-06 | |||
JPH06307330A | 1994-11-01 | |||
JPH10122129A | 1998-05-12 | |||
JPH05195946A | 1993-08-06 | |||
JPH09256945A | 1997-09-30 |
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