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. 16, 1978
Filed:
May. 09, 1977
Howard L Johnson, Joliet, IL (US);
Caterpillar Tractor Co., Peoria, IL (US);
Abstract
Pressurized fluid is supplied to fluid-driven mechanisms by a variable displacement supply pump through a check valve and a flow control valve. A compensator receiving a pressure feedback signal from the control valve side of the check valve increases pump displacement in response to a pressure signal drop and decreases pump displacement in response to a rise in the signal pressure to compensate for variations in demand. Part of the supply pump output is used to drive a small fluid motor which turns a small pressure signal-amplifying pump connected in parallel with the check valve. The check valve opens to transmit the variable displacement pump output to the driven mechanisms when the control valve is opened. When the flow control valve is closed the check valve also closes enabling the fluid motor and pressure signal-amplifying pump to maintain the feedback signal to the compensator at a high pressure while the actual output pressure of the supply pump drops owing to the reduced displacement caused by the high feedback signal. The resulting internal pressure reduction in the supply pump during standby periods greatly reduces leakage which translates into power and fuel or energy savings.