Plasma ignition system
AssigneeNissan Motor Co., Ltd.
InventorHiroshi Endo
Life of this patent
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Abstract
A plasma ignition system for an internal combustion engine which can prevent irregular ignition when the insulation between the electrodes of the spark plug deteriorates due to carbon on the electrodes, and further can prevent electrical noise from being emitted. The system according to the present invention comprises a plasma ignition energy storing condenser, a plurality of switching units, and boosting transformers one each for each of the engine cylinders. In this system, a high tension is generated at the secondary coil of the boosting transformer to generate a spark between the electrodes of the plug and subsequently a large current is passed through the electrodes by the remaining energy stored in the condenser.
Claims16
A plasma ignition system for an internal combustion engine which comprises:
- (a) a plurality of plasma spark plugs, one terminal of each being grounded;
- (b) a DC--DC converter for boosting a DC supply voltage to a high tension;
- (c) an ignition energy condenser for storing electric ignition energy, said ignition energy condenser being connected to the output of said DC--DC converter;
- (d) a plurality of switching units each for applying the ignition energy charged in said ignition energy condenser to the respective plasma spark plug with an appropriate ignition timing, said switching units being connected to said ignition energy condenser;
- (e) a plurality of boosting transformers each for boosting the voltage across said ignition energy condenser to a still higher voltage, the common terminal of the respective primary and secondary coils being connected to said respective switching units, the other terminal of the respective secondary coil being connected to the terminal of said respective plasma spark plug other than the grounded terminal;
- and
- (f) a plurality of auxiliary condensers each for connecting the other terminal of the primary coil of said respective boosting transformer to the ground, said auxiliary condensers forming an oscillation circuit together with the primary coil of said boosting transformer,
- whereby when said switching unit is turned on in order to discharge a current from said ignition energy condenser to said auxiliary condenser through the primary coil, a high tension is generated at the secondary coil of said boosting transformer so as to generate a spark between the electrodes of said plasma spark plug and subsequently a large current is passed through the electrodes of said plasma spark plug by the remaining plasma ignition energy stored in said ignition energy condenser so as to produce a plasma therebetween for completing the plasma ignition.
A method of plasma-igniting the fuel in the cylinders of an internal combustion engine, which comprises the steps of:
- (a) boosting a supply voltage to a high tension;
- (b) storing the boosted high-tension ignition energy in a condenser;
- (c) discharging part of the ignition energy stored in the condenser through one of a plurality of oscillation circuits including the primary coil of a boosting transformer and an auxiliary condenser, respectively, so as to generate a spark due to a still higher voltage across the secondary coil thereof at the appropriate ignition timing, so that the space between the electrodes of one of a plurality of spark plugs becomes conductive with a certain discharge resistance;
- and
- (d) discharging the remaining energy stored in the condenser, through the secondary coil of the boosting transformer, to the space between the electrodes of the spark plug so as to produce a plasma therebetween for igniting the mixture within the cylinder.
Dependencies are inferred from the claim text.