Control valve for construction equipment
US4858651A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 12, 1988 |
| Grant date | Aug 22, 1989 |
| Priority date | — |
| Expiry date | Oct 12, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/87764
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A control valve for construction equipment adapted to operate a control mechanism in which a central by-pass passage is provided with a pilot pressure generating mechanism such as an orifice or the like and which is adapted to generate a pilot pressure due to pressure loss of fluid passed through the pilot pressure generating mechanism when a valve connected to the central by-pass passage is set at an open position, resulting the pilot pressure acting to control a discharge rate of a variable discharge pump. The control valve includes a valve body, in which a first spool and a second spool are arranged in series in such a manner that inner ends of the first and second spools are opposite to each other. An outer end of the second spool faces a second pilot chamber. A centering spring is arranged so as to act on an outer end of the first spool, so that the inner ends of both spools may be abutted against each other and received in a first pilot chamber when the spools are at their normal position. The application of a pilot pressure to the first pilot chamber causes the first spool to be moved against the centering spring to close the central bypass passage. Also, application of a pr…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.