Electrically controllable valve assembly
US4478245A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 25, 1982 |
| Grant date | Oct 23, 1984 |
| Priority date | — |
| Expiry date | Aug 25, 2002 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/8242
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
An electrically controllable valve assembly for hydraulic adjustment of a piston includes a pilot valve controllable by an electronic controller. The pilot valve has a spool and a restrictor array comprising first and second variable restrictor means and a fixed restrictor means, through which flows an auxiliary bleedflow of hydraulic fluid. The variable restrictor means are adjusted in opposite directions in order to produce from the bleed flow a control pressure which is responsible for positioning of the piston of the valve assembly. A pressure drop is taken off at the fixed restrictor means, and acts on the spool to produce a negative feedback action, thereby always to produce a given displacement control flow, irrespective of the system pressure, while avoiding control oscillations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.