Piston and hydraulic pump or motor

Patent metadata

Field	Value
Publication number	US-2022010786-A1
Application number	US-201917288149-A
Country	US
Kind code	A1
Filing date	Nov 15, 2019
Priority date	Nov 15, 2018
Publication date	Jan 13, 2022
Grant date	—

Abstract

A piston is provided with a piston body that includes an internal space and a leading end member that includes an insertion portion placed in the internal space and a protrusion protruding from a leading end surface of the piston body.

First claim

1 . A piston comprising:
a piston body including an internal space; and a leading end member including an insertion portion placed in the internal space and a protrusion protruding from a leading end surface of the piston body.

2 . The piston according to claim 1 ,
wherein the protrusion has a surface inclined to approach a central axis while getting farther from the leading end surface in an axial direction parallel to the central axis of the piston body.

3 . The piston according to claim 1 ,
wherein the protrusion has a surface placed inside an outer periphery of the piston body in a radiation direction of a central axis of the piston body.

4 . The piston according to claim 1 ,
wherein the leading end surface is placed around an opening of the piston body connected to the internal space, and the leading end member has an opposed surface facing the leading end surface.

5 . The piston according to claim 4 comprising
an oil passage disposed between the leading end surface and at least a part of the opposed surface and between an inner surface of the internal space and at least a part of an outer surface of the insertion portion.

6 . The piston according to claim 1 ,
wherein the leading end member has a density less than or equal to a density of the piston body.

7 . The piston according to claim 1 comprising
a connection member placed in the internal space and connected to the insertion portion,
wherein the insertion portion includes a deformable portion placed around the connection member and configured to deform outward in a radiation direction of a central axis of the piston body upon contact with the connection member.

8 . The piston according to claim 7 ,
wherein the connection member has an outer surface at least a part of which is inclined to approach a central axis of the piston body while getting closer to the leading end surface in an axial direction parallel to the central axis.

9 . The piston according to claim 7 ,
wherein the leading end member includes a through hole parallel to the central axis of the piston body, the connection member includes a screw hole formed with a thread groove, and the piston comprises a bolt including a shaft placed in the through hole and a leading end including a thread connected to the thread groove.

10 . The piston according to claim 7 ,
wherein the connection member has a density less than or equal to a density of the piston body.

11 . A hydraulic pump or motor comprising:
a cylinder block including a cylinder in which the piston according to claim 1 is placed; a piston shoe disposed at a base end of the piston; and a swash plate configured to support the piston shoe.

Assignees

• Komatsu Mfg Co Ltd

Inventors

• Koide Shunsuke
• MOTOSHIMA Hiroaki
• KAWAKITA Shigeyoshi

Classifications

• F04B1/12 Primary

  having cylinder axes coaxial with, or parallel or inclined to, main shaft axis · CPC title

• F04B53/18

  Lubricating · CPC title

• F04B53/14

  Pistons, piston-rods or piston-rod connections · CPC title

• F03C1/0605

  Adaptations of pistons (pump pistons F04B1/124, F04B53/14) · CPC title

• F04B1/124 Primary

  Pistons · CPC title