Patent ID: 7913492
Filing Date: 2011-03-29
Classification: F16H

Abstract:
1. A hydrostatic continuously variable transmission configured by connecting a hydraulic pump and a hydraulic motor via a hydraulic closed circuit to enable variably controlling of the capacity of at least either of the hydraulic pump or the hydraulic motor, shifting the input revolution speed of the hydraulic pump and acquiring the output revolution speed of the hydraulic motor, the hydrostatic continuously variable transmission comprising: a valve spool movably arranged in a spool hole axially extending in a supporting shaft for rotatably supporting the hydraulic pump and the hydraulic motor; a clutch oil passage on a high pressure side connected to an oil passage on the high pressure side forming the hydraulic closed circuit and open to the spool hole; and a clutch oil passage on a low pressure side connected to an oil passage on the low pressure side forming the hydraulic closed circuit and open to the spool hole; wherein the valve spool is provided with a guide part fitted into a guide hole formed in the supporting shaft and guided to be axially moved in the spool hole, and a valve part that is fitted to a part in which the clutch oil passage on the high pressure side and the clutch oil passage on the low pressure side in the spool hole are open for connecting and cutting off the clutch oil passage on the high pressure side and the clutch oil passage on the low pressure side according to the axial movement; and the valve spool is formed by coupling a first spool member provided with a part for forming the guide part, and a second spool member provided with a part for forming the valve part, wherein the first spool member has a fitting concave portion and a first coupling hole extending in a direction perpendicular to a moving axis of the valve spool, the second spool member has a fitting convex portion protruded axially, the fitting convex portion has a second coupling hole in a direction perpendicular to the moving axis of the valve spool, and the fitting convex portion of the second spool is fitted into the fitting concave portion of the first spool, the first coupling hole matches the second coupling hole, a coupling pin is inserted into the first and second coupling holes to connect the first spool member and the second spool member together, an annular holding groove concave in a circumferential direction and formed on a periphery of the first coupling hole and a ring fitted within the holding groove, said ring being formed of a coil acquired by bending a wire wherein a section is circular or rectangular and the ring has a plurality of turns.