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:
Mar. 26, 2002
Filed:
Jul. 18, 2000
Axel Widemann, Neumunster, DE;
Sauer-Danfoss Inc., Ames, IA (US);
Abstract
In a hydraulic vehicle drive which has a hydraulic circuit consisting of a variable displacement pump ( ) and a hydraulic motor ( ), the variable displacement pump ( ) is driven by a diesel engine ( ). During the braking or overrunning operation of the vehicle, the hydraulic motor becomes the pump and drives the variable displacement pump ( ) which acts as a motor on the diesel engine ( ) and attempts to accelerate the latter. The braking effect which is intended and obtained thereby involves the risk of the diesel engine ( ) reaching impermissibly high rotational speeds. The braking therefore takes place in a controlled manner by a sequence valve ( ) being arranged in the line ( ) between the hydraulic motor ( ) and the variable displacement pump ( ). The sequence valve acts on the pivot angle of the variable displacement pump ( ) via the pump bypass line ( B). The control takes place in such a manner that the product of the displacement volume of the variable displacement pump ( ) and of the pressure of the hydraulic fluid in the line ( ) upstream of the variable displacement pump ( ) remains approximately constant. In addition, flow control valves ( ) may also be present.