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:
Apr. 09, 1996
Filed:
Oct. 05, 1994
Edward H Phillips, Troy, MI (US);
Techo Corporation, Southfield, MI (US);
Abstract
A power steering system (10) for a motor vehicle having a power cylinder with the piston mounted in the power cylinder which divides the power cylinder into first (30) and second (32) chambers. The steering system includes a valve assembly having a rotary input member (40) and a valve sleeve 42 and first and second pairs of open center input valves (18), each which has an inlet and an outlet. The inlets of the input valves are fluidly connected to pump output. The valve assembly further includes a pair of closed center input valves (4b) and a normally closed by-pass valve (50). A hydraulic pump (12) is controlled so as to maintain a constant pressure drop between the inlets and outlets of the closed center valve (4b) and normally closed by-pass valves (50) whereby initial fluid flow through the control valve is proportional to the area of a variable orifice comprised within the normally closed by-pass valve (50). When sufficient torque is applied to the rotary input member (40) one of the closed center valves (46) begins to open whereby total flow through the control valve is proportional to the combined area of orifices comprised within both the opening of closed center valve (4b) and the normally closed by-pass valve (50).