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:
Oct. 08, 2013
Filed:
Feb. 28, 2008
Hidetoshi Satake, Ishioka, JP;
Katsuaki Kodaka, Abiko, JP;
Yuuki Gotou, Tsuchiura, JP;
Yuuji Nagashima, Tsuchiura, JP;
Kazuhiro Ichimura, Kasumigaura, JP;
Hidetoshi Satake, Ishioka, JP;
Katsuaki Kodaka, Abiko, JP;
Yuuki Gotou, Tsuchiura, JP;
Yuuji Nagashima, Tsuchiura, JP;
Kazuhiro Ichimura, Kasumigaura, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
There are provided: control valves-that control flow of pressure oil from the hydraulic sourceto the hydraulic actuators-; electric lever devices-that output electrical operation signals v-vin correspondence to lever operation; electromagnetic proportional valves-through which control pressures for controlling the control valves-are output; a pressure calculating unitthat calculates control pressures P-Pin correspondence to the operation signals V-v; a control unitthat controls the electromagnetic proportional valves-so that control pressures to be output from the electromagnetic proportional valves-become the control pressures P-Pthat have been calculated; a high-pressure selection circuit-that selects a higher pressure between control pressures that have been output from the electromagnetic proportional valves-; pressure detectorsandthat detect a control pressure selected by the high-pressure selection circuit-; an abnormality determination unitthat determines an abnormality in the electromagnetic proportional valves-based upon the control pressure detected by the pressure detectorsandand the control pressure calculated by the pressure calculating unit; and an inhibiting deviceandthat prohibits control of the control valves-when it is determined that an abnormality has occurred in the electromagnetic proportional valves-