Ionic current detection circuit based on automotive ignition system

Abstract

The invention discloses an ionic current detection circuit based on an automotive ignition system, which comprises a series circuit composed of a secondary coil of an ignition coil, a spark plug, a first resistor and a bias circuit. The bias circuit comprises a voltage regulator diode and a first capacitor connected in series with each other, wherein a cathode terminal of the voltage regulator diode is connected with the secondary coil of the ignition coil, and an anode terminal of the voltage regulator diode is connected with the first resistor. A point of common connection for the spark plug and the first resistor is grounded, while a third diode is reversely connected between the point of common connection and the ground. Second diodes are connected in series to two ends of the first resistor. A point of common connection for the bias circuit and the first resistor serves as a first ionic voltage test point which is connected with a signal processing circuit, and an output end of the signal processing circuit serves as a second ionic voltage test point. The ionic current detection circuit is capable of timely monitoring combustion characteristics of an engine.

Description

technical field [0001] The invention relates to an automobile ignition system, in particular to an ion current detection circuit based on the automobile ignition system. Background technique [0002] At present, the ion current method is widely used, especially in the application research of automobile ignition detection and control. The so-called ion current method is to use the spark plug of the engine itself as a sensor, and add an appropriate bias voltage between the two electrodes of the spark plug. When the mixed gas in the combustion chamber of the engine is burned, the mixed gas is ionized, and the spark plug gap The charged ions flow directionally under the action of an external electric field (bias voltage), and the formed current is the ion current, also known as the spark plug ion current. [0003] In the field of automobile engines, people began to use the ion current method to monitor engine misfire, monitor whether the engine knocks, etc., in order to improve...

AI Technical Summary

Problems solved by technology

Since the ignition coil of an automobile ignition system is generally composed of a primary coil and a secondary coil, and because the voltage of the ignition coil is an oscillating voltage, the voltage coupled to the primary coil from the high-voltage end of the secondary coil is alternately positive and negative, while In the circuit of the prior art, when the ion current method is used to monitor the engine misfire and knock, people can only use the negative high voltage for detection. Therefore, the detection time of the positive high voltage is missed, so that it is impossible to detect whether the engine has misfire or knock in time and so on

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