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:
May. 20, 1997
Filed:
Nov. 16, 1995
Yoshiyasu Itsuji, Chiba, JP;
Shinji Terada, Chiba, JP;
Sumitomo Heavy Industries, Ltd., Tokyo, JP;
Abstract
In a hydraulic driving apparatus with a bladder-type accumulator connected to a fluid supply pipe extending from a hydraulic fluid source to at least one actuator, the apparatus comprises a hydraulic pressure sensor attached to the fluid supply pipe in the vicinity of the bladder-type accumulator and a control unit responsive to a detected pressure detected by the hydraulic pressure sensor for controlling the hydraulic fluid source. The control unit carries out the steps of judging, at the start of the hydraulic driving apparatus, an initial gas pressure supplied to the bladder-type accumulator with reference to a gradient of variation of the detected pressure detected by the hydraulic pressure sensor; monitoring, during a normal operation of the hydraulic driving apparatus, a difference .DELTA.P between the initial gas pressure and the detected pressure; and judging occurrence of a trouble when the difference .DELTA.P becomes smaller than a predetermined first difference .DELTA.P1 or when the difference .DELTA.P becomes greater than a predetermined second difference .DELTA.P2 (.DELTA.P1<.DELTA.P2).