Speed control devices
US3963091A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 3, 1975 |
| Grant date | Jun 15, 1976 |
| Priority date | — |
| Expiry date | Mar 3, 1995 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02B1/04
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
This invention relates to a speed control system which is operable to maintain a vehicle at a selected speed, or to prevent the vehicle speed dropping below the selected speed. The system includes an electrically-operable pressure control valve which is arranged to be fed with fluid from a source of fluid pressure, for example from the transmission oil pump of an automatic transmission system, an electronic control circuit having a memory in which a selected vehicle speed can be set by the driver, and which supplies a control signal in the form of a variable mark/space ratio pulse train representative of the difference between the actual and selected speeds, to the electrically operable control valve. Fluid pressure from the pump is applied to the smaller working area side of a displaceable differential piston of a differential area piston arrangement, and the larger working area side of the differential piston is connected to the output side of the control valve. The control valve is modulated by the variable control signal to correspondingly vary the pressure applied to the larger area side of the differential piston, and correspondingly displace the piston. The piston is connect…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.