The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 21, 2000
Filed:
Jul. 10, 1997
Yasuhiro Takahashi, Tokyo, JP;
Wataru Fukui, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A combustion state detecting apparatus for an internal-combustion engine does not incur deteriorated ignition characteristics because the ionic current detecting circuit thereof is not affected by ignition current. The combustion state detecting apparatus is equipped with an ionic current detecting circuit (10A) which includes a biasing device (C) connected to the low voltage end of a secondary winding (2b) of an ignition coil (2) and which detects ionic current (i) flowing from the biasing device via a spark plug (4); rectifying device (5) which is inserted between the biasing device and the secondary winding so that the ionic current flows in the forward direction; a voltage clamping device (6) inserted between the secondary winding and the ground; and an ECU (20) which detects the combustion state according to the ionic current. The biasing device applies a bias voltage (VBi) of the opposite polarity from the high voltage for ignition to the spark; and the voltage clamping device limits a voltage (Vc) at the low voltage end of the secondary winding to a predetermined value when the high voltage for ignition appears, the absolute value of the predetermined value being set to the absolute value or more of the bias voltage.