Hydraulic power steering apparatus
US5474145A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Sep 13, 1994 |
| Grant date | Dec 12, 1995 |
| Priority date | — |
| Expiry date | Sep 13, 2014 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB62D5/062
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A hydraulic power steering system includes a pump, a flow control valve, and a bypass control valve. The flow control valve responds to a pressure drop across a metering orifice disposed in a fluid supply passage so as to control the flow rate of operational fluid by bypassing part of the operational fluid to a reservoir. A spring chamber of the flow control valve is connected to the supply passage through a control orifice. The bypass control valve is disposed between the spring chamber and the reservoir so as to increase the amount of bypassed fluid by controlling the pressure in the spring chamber. The bypass control valve has a control spool, a load pressure introduction port connected to the upstream side of the control orifice for leading the load pressure to a first end of the control spool and a pilot port connected to the downstream side of the control orifice for leading the pressure in the spring chamber of the flow control valve to a second end of the control spool. Moreover, a pressure receiving area of the second end of the control spool is smaller than that of the first end of the control spool. Accordingly, a spring having a small spring constant can be used in the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.