Lift control valve and feedback system
US6533044B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 2, 2001 |
| Grant date | Mar 18, 2003 |
| Priority date | — |
| Expiry date | Jun 15, 2021 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T74/2054
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A control valve and feedback system has three operating states including a lifting state, a neutral state, and a lowering state. The feedback control system comprises a cylinder, a pump, a reservoir for holding working fluid, and a control valve. The control valve comprises a valve body having first and second ends with a bore defined therebetween. The valve body further comprises an inlet port, a return port, a first work port and a second work port. The inlet port, return port, and first and second work ports are defined in the valve body. The inlet port communicates with the bore and the pump. The return port is in fluid communication with the bore and the reservoir. The first work port is also in communication with the bore and the cylinder in the lifting state. The control valve is plumbed backwards so that the first work port and the second work port are in fluid communication in the lowering state. The valve also comprises a check valve disposed in the first work port. The first check valve is adapted to achieve the neutral state and being selectively adjustable to achieve said lowering state.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.