Measuring circuit for sensing ionisation within a cylinder of a combustion engine
US5907243A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 23, 1997 |
| Grant date | May 25, 1999 |
| Priority date | — |
| Expiry date | Sep 23, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R29/24
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A measuring circuit for sensing ionization within a combustion chamber of an engine is arranged in the grounded end of the secondary winding (5) of an ignition coil (2), and includes a voltage source for measurements having a substantially constant potential. The voltage source for measurements used is a capacitor 13 which is charged by the spark current SC, and subsequently after the ignition spark goes out will apply a bias voltage over the spark plug gap 3 with a reversed polarity in relation to the spark voltage. The ionisation within the combustion chamber is detected with a measuring resistance 14 arranged in series with the capacitor 13. A rectifying element 11 is connected in parallel with the measuring resistance, which will secure that the spark current is developed in the spark plug gap 4 and that the measurement current passes through the measuring resistance 14. The rectifying element is grounded with a separated ground strap which does not pass the ground plane of the measuring resistance. The interference inducing spark current may then be conducted in a separated circuit without having to pass the ground plane used for the remaining electronic components of the circ…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.