Method and apparatus for sensing piston position
US6005395A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 12, 1997 |
| Grant date | Dec 21, 1999 |
| Priority date | — |
| Expiry date | Nov 12, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/88
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system for determining the position of a piston moveable within a cylinder, or of an implement or joint, is disclosed herein. Electromagnetic (EM) bursts such as ultra-wideband or frequency pulses are generated and applied to a transmitter/receiver unit. The EM bursts are launched by the transmitter via a focusing antenna assembly from an end of the cylinder housing towards the piston. The fluid in the cylinder housing is in electrical communication with the piston such that a surface of the piston represents an electrical impedance discontinuity which causes the EM bursts to be reflected back to the receiver. The time for the EM bursts to travel from the transmitter to the piston and for the reflections to travel back to the receiver via the antenna assembly is determined and converted into a position signal representing the piston's position. A compensation signal can be used to compensate the position signal for variations in a parameter of the fluid within the cylinder. The parameter may be the dielectric constant, and the variations may be caused by factors such as temperature, contamination and fluid type. The compensation circuit can include a pulse level analyzer, resonan…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.