Swash-plate hydraulic motor or swash-plate hydraulic pump
The present invention addresses the problem of providing a swash-plate hydraulic motor or a swash-plate hydraulic pump having a structure in which the swash plate can be stably held without mounting a shoe to the swash plate-side end of a tilt control piston. An example of the embodiment of the present invention is a swash-plate hydraulic motor ( 1 ). A spherical section ( 8 b ) is integrally formed on the swash plate-side end surface of a tilt piston ( 8 ), and a groove ( 10 ) into which the spherical section ( 8 b ) is fitted in a slidable manner is formed in the support surface ( 7 b ) (second support surface ( 7 b 2 )) of the swash plate ( 7 ). The groove ( 10 ) is a part of the second support surface ( 7 b 2 ) and has a shape having a predetermined width and having a longitudinal direction which is oriented perpendicularly to the direction which connects two pivots ( 11 ).
1. A swash-plate hydraulic motor or a swash-plate hydraulic pump comprising:
a main body casing;
a rotation axis housed in the main body casing;
a cylinder block attached to the rotation axis;
cylinder holes formed in the cylinder block;
pistons slidably inserted into the cylinder holes;
shoes attached to leading ends of the pistons;
a swash plate including a slope on which the shoes slide and a supported surface which is formed on the side opposite to the slope and is supported by the main body casing via two pivots;
a tilt piston which is in contact with the supported surface of the swash plate and is configured to tilt the swash plate by pressing the swash plate toward the pistons; and
a cylinder hole for the tilt piston, the cylinder hole being formed in the main body casing and into which the tilt piston is slidably inserted, a spherical surface member being formed at an end face on the swash plate side of the tilt piston in an integrated manner, a recess with which the spherical surface member is slidably engaged, the recess being formed in the supported surface of the swash plate,
wherein a bottom surface of the recess is formed to be arc-shaped in a direction connecting the two pivots with each other, and
wherein the bottom surface of the recess is formed to be flat in a direction orthogonal to the direction connecting the two pivots with each other over an entire length of the recess, and
wherein the tilt piston is configured to be movable between an extended position in which the tilt piston presses the swash plate towards the pistons and a retracted position,
wherein, as the tilt piston moves between the extended position and the retracted position and the swash plate pivots about the two pivots, the spherical surface member of the tilt piston is configured to engage the bottom surface of the recess at different positions of the recess, and
wherein the different positions are spaced apart longitudinally in the direction orthogonal to the direction connecting the two pivots with each other.
2. The swash-plate hydraulic motor or a swash-plate hydraulic pump of claim 1 , wherein the supported surface of the swash plate includes a first supported surface and a second supported surface, each of the first and second supported surfaces make a different angle with respect to the rotation axis.
3. The swash-plate hydraulic motor or a swash-plate hydraulic pump of claim 2 , wherein the swash plate is arranged to be swingable with the two pivots as fulcrums, between a first position where the first supported surface is in contact with the main body casing and a second position where the second supported surface is in contact with the main body casing.
4. The swash-plate hydraulic motor or a swash-plate hydraulic pump of claim 2 , wherein the recess is formed on the second supported surface.
5. The swash-plate hydraulic motor or a swash-plate hydraulic pump of claim 1 , wherein the recess extends, longitudinally in the direction orthogonal to the direction connecting the two pivots with each other, from the center of the rotation axis to an outer circumference of the swash plate.
6. The swash-plate hydraulic motor or a swash-plate hydraulic pump of claim 1 , wherein the recess has a pre-determined width, and wherein the arc-shaped bottom surface of the recess has a radius of curvature that is constant over the entirety of the pre-determined width of the recess and in the direction connecting the two pivots with each other.
7. The swash-plate hydraulic motor or a swash-plate hydraulic pump of claim 1 , wherein the bottom surface of the recess has a first radius of curvature and the spherical surface member of the tilt piston has a second radius of curvature, wherein the first radius of curvature of the bottom surface of the recess is different from the second radius of curvature of the spherical surface member of the tilt piston.