The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 04, 2001
Filed:
Sep. 20, 1999
Komatsu Ltd., Tokyo, JP;
Abstract
The invention can prevent a heat generation and a seizure due to a sliding friction between a piston and a cylinder in inclined shaft type and swash plate type hydraulic pumps even when they are made high speed. In order to achieve this, a piston pump motor comprises a cylinder block (,) rotatably supported within a case (,), having suction and discharge ports (,) in a side of one cylindrical end surface, being provided with a plurality of cylinder holes (,) connected to the suction and discharge ports and arranged on an inside circumference at a uniform interval, and a piston (,) rotated by a drive shaft (,), sliding within the cylinder hole in a sealing manner and having a part moving forward and backward from a side of the other end surface of the cylinder block, wherein an oil introduction groove (,) communicating with an inner portion of the case is provided in any one of a portion disposed on an outer periphery of the piston and moving forward and backward from the side of the other end surface of the cylinder block, and a portion disposed on an inner periphery of the cylinder hole and at which a part of the piston moves forward and backward from the side of the other end surface.