Internal-combustion engines – High tension ignition system – Additional spark energy supply
Patent
1985-05-09
1986-10-28
Nelli, Raymond A.
Internal-combustion engines
High tension ignition system
Additional spark energy supply
123618, 123596, 123598, 123605, F02P 100
Patent
active
046192417
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an ignition device for internal combustion engines and, more particularly, to a high-energy ignition device in which the output from a DC-DC converter is superposed on the discharge current through a spark plug such as to attain a long duration of the discharge in the spark plug.
An ignition device allows a high voltage discharge between two electrodes of a spark plug so as to ignite a mixture in the engine, thereby triggering an explosive combustion. In order to attain a higher fuel economy and higher output power, it is necessary to effect stable and efficient combustion of the mixture.
A high voltage on the order of 10 to 20 KV is required for breaking the insulation across the electrode gap in the spark plug. However, once the insulation is broken, the discharge can be maintained with only a medium-high voltage of 1 to 2 KV.
In view of this fact, a proposal has been made in which a high voltage pulse, generated by an ignition coil, is initially applied to break the insulation in the spark plug and, after the breakage of the insulation, a medium-high voltage generated by a DC-DC converter is superposed on the discharge current, to thereby maintain the discharge for a longer time. This ignition device, however, requires complicated wiring for connecting three constituent elements: namely an IC igniter, ignition coil and a DC-DC converter. It is quite troublesome to find sufficient room for accommodating these components and wiring in the restricted space of the engine compartment.
An object of the invention is to provide a high-energy ignition device which permits simplification of the wiring and reduces the overall size of the device.
To this end, according to the invention, there is provided a high-energy ignition device in which a spark plug and an output transformer of a DC-DC converter are subjected to an insulation treatment and, after laying electric connection between major portions, the spark plug and the DC-DC converter are integrated with forming resin such as to withstand vibration while maintaining necessary insulation of the spark plug and the output transformer of the DC-DC converter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit diagram of a high-energy ignition device to which the invention is applied;
FIG. 2 is a front elevational view of a high-energy igniation device in accordance with the invention;
FIG. 3 is a perspective view of a high-energy ignition device in accordance with the invention; and
FIG. 4 is a sectional view of the high-energy ignition device of the invention, taken along the line IV--IV of FIG. 2.
DETAILED DESCRIPTION
Referring now to the drawings wherein like reference numerals are used throughout the various views to designate like parts and, more particularly, to FIG. 1 according to this figure, a circuit of a high energy ignition device includes a battery 10 connected through a key switch 12 to an igniter coil 14 and an output transformer 18 of a DC-DC converter 16. The igniter coil 14 has a primary coil 20, one terminal 22 of which is connected through a line 23 to a line 24 leading to the battery 10, while the other terminal 26 is connected through a line 28 to the collector 34 of a transistor 32 in an ignition circuit 30. The emitter 36 of the transistor 32 is grounded, while the base 38 receives the output signal from a pickup coil 40 which generates a signal synchronous with the engine operation. A circuit connected between the pickup coil 40 and the base of the transistor 32 is well known to those skilled in the art and, therefore, is not described in detail. The transistor 32 is adapted to be turned on and off by the output from the pickup coil 40 in synchronism with the engine operation, thereby interrupting the electric current in the primary coil 20 of the igniter coil 14. A secondary coil 44, magnetically coupled to the primary coil 20 through an iron core 42, is adapted to produce a high-voltage pulse when the current in the primary coil 20 is abruptly interrupted. The seconda
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Hitachi , Ltd.
Nelli Raymond A.
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