Circuit arrangement for measuring an ion current in a combustion chamber of an internal combustion engine
US6043660A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Feb 18, 1997 |
| Grant date | Mar 28, 2000 |
| Priority date | — |
| Expiry date | Feb 18, 2017 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02P2017/125
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
A circuit arrangement measures an ion current generated in the combustion chamber of an internal combustion engine during an iron current flow phase following an ignition phase. A voltage drop across a feedback resistor (R.sub.1) connected in parallel to an inverting amplifier is measured since the voltage drop is proportional to the ion current resistance. The amplifier is connected with its inverting input to a low voltage end of a secondary winding of an ignition transformer or coil. The high voltage end of the secondary winding is connected through a spark gap of a spark plug to ground, whereby the spark plug functions as an ion current sensor during the ion current flow phase. Negative voltage peaks flowing during an ignition phase and the ignition current flowing during the ignition phase are diverted through respective first and second circuit branches. The first branch has a first semiconductor diode (D.sub.1) grounding the low voltage end of the secondary winding for discharging the negative high voltage peaks while blocking the ignition current. The other diverting branch has a second semiconductor (D.sub.2) connected in parallel to the inverting amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.