JPH01124404U - - Google Patents

Description

[Brief explanation of the drawing]

1 and 2 show a first embodiment, FIG. 1 is a longitudinal sectional view showing a motor capacity control device according to this embodiment, and FIG. 2 is a diagram showing the relationship between driving pressure and motor capacity. , FIG. 3 is a longitudinal sectional view similar to FIG. 1 showing the second embodiment, FIG. 4 is a longitudinal sectional view similar to FIG. 1 showing the third embodiment, and FIG. 5 is a longitudinal sectional view similar to FIG. 1 showing the third embodiment. A vertical sectional view similar to FIG. 1 showing an embodiment, FIGS. 6 and 7 relate to the prior art, FIG. 6 is a circuit configuration diagram showing a hydraulic motor capacity control device according to the prior art, and FIG. FIG. 3 is a diagram showing the relationship between driving pressure and motor capacity. 1... Hydraulic motor, 1A... Capacity variable part, 2A, 2
B...Hydraulic piping, 3...High pressure selection valve, 11...Casing, 12...Casing body, 13...Lid body, 14...
Cylinder, 16... Control piston, 17... Spool cylinder, 19, 61... Spool, 20, 65
...Compression spring, 21,62...Cylinder for command piston, 22,63...Command piston, 23,64...Oil hole, 24...Pressure introduction port, 25,29,32,
66, 70, 71... Communication port, 26, 67... Switching port, 27, 68... Communication path, 28, 31, 6
9... Circumferential groove, 30, 33... Communication port, 34... Switching valve, 35... External hydraulic power source, A... Large oil chamber, B... Small oil chamber, C, J... Spring chamber, D, H... Spool annular chamber, E
, G... Spool end chamber, F, K... Action chamber.

Claims (1)

[Scope of utility model registration request] A casing whose inside is a cylinder, and one end of which is slidably attached to the cylinder of the casing, defining the interior into a large oil chamber and a small oil chamber, and the other end of which protrudes outside the casing to accommodate a hydraulic motor. a control piston connected to a variable capacity portion of the control piston; a spool slidably provided in a spool cylinder formed on the control piston; a spool annular chamber formed in the axially intermediate position and always communicating with the small oil chamber, a spring chamber formed at one of the shaft ends, a spool end chamber formed at the other shaft end, and the spring chamber. a spring that biases the spool toward the axial end of the control piston; a command piston that forms an action chamber in the spool that constantly communicates with the spool annular chamber; a pressure introduction port introduced into the oil chamber, and formed in the control piston,
Normally, the large oil chamber is communicated with the spring chamber by the spool, and when the spool is displaced against the spring in response to the driving pressure introduced into the action chamber,
a switching port that communicates the large oil chamber with the spool annular chamber; a communication port that communicates the spring chamber with the casing or the outside of the control piston; and another communication port that communicates the spool end chamber with the casing or the outside of the control piston; Capacity control of a hydraulic motor comprising a switching valve that selectively connects one of the communication ports to a hydraulic source and a drain, and a drain that is constantly connected to the other communication port of the communication ports. Device.