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:
Feb. 29, 2000
Filed:
Oct. 19, 1998
Mitsuru Arai, Oyama, JP;
Hiroshi Endo, Tochigi-ken, JP;
Komatsu Ltd., , JP;
Abstract
A communication area of a left pressure reception chamber, a pressure reception chamber, a right pressure reception chamber and another pressure reception chamber for moving a spool to first and second positions with a first pump port and a second pump port is made large at the beginning of a stroke, small at the intermediate of the stroke and medium at the end of the stroke so as to return the spool from the first and second positions to the neutral position in a short time while preventing cavitation from occurring. While the volume of the pressure reception chamber located opposite to the moving direction of the spool is prevented from changing, the spool is moved slowly in the above-described opposite direction. Thus, the spool is prevented from making an over-stroke and also prevented from having a hunching even if a return pressure oil has a large change in pressure.