Pressure sensing apparatus
US4475402A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 1982 |
| Grant date | Oct 9, 1984 |
| Priority date | — |
| Expiry date | Jun 30, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L9/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An etched metal membrane has its rim laser-welded or electron-beam-welded to a ring made of the same kind of metal within which a central electrode is held by a metal-to-glass seal. The welding is done in vacuum to avoid the necessity of later evacuation. The pressure sensor capacitance thus formed is connected through an impedance converter to an oscillator circuit which provides an output frequency that varies with the sensed pressure. The inner surface of the central electrode is flush with the surface of the rim to which the membrane is welded to reduce variations in capacitance of the sensor, and any residual variations are compensated by a resistance balance in the evaluation circuit. The insensitivity of the system to temperature and its service life make it suitable for sensing the intake air pressure of an internal combustion engine.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.