Internal-combustion engines – High tension ignition system – Additional spark energy supply
Patent
1993-04-30
1995-06-06
Cross, E. Rollins
Internal-combustion engines
High tension ignition system
Additional spark energy supply
123653, F02P 900
Patent
active
054213126
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an electrical circuit for use in a spark-ignition internal combustion engine.
In a conventional spark-ignition internal combustion engine, spark plugs are connected to a high voltage supply such as an iginition coil through a distributor. The distributor periodically closes a conductive path between each spark plug and the coil so as to enable a high voltage to be applied across a gap defined by the spark plug. The high voltage is sufficient to generate a spark between the electrodes of the spark plug. The distributor is connected via a single high tension lead to the coil and by respective high tension leads to each of the spark plugs.
A great deal of attention has been paid to optimising spark timing and the conditions within the engine cylinders to which the spark plugs are fitted. Little attention has been given to the nature of the spark itself other than to ensure that the spark is sufficiently large to reliably ignite an air/fuel mixture.
It is an object of the present invention to provide an electrical circuit which enables the spark generated by a ignition coil to substantially enhance the performance of internal combustion engines.
According to the present invention there is provided an electrical circuit for connection to a high tension lead which is connected to a spark plug of a spark ignition internal combustion engine, the circuit comprising a capacitor the capacitance of which is such that, if a high voltage pulse is applied to the high tension lead, the voltage developed across the capacitor and the charge stored by the capacitor are sufficient to initiate and sustain an iginition spark, the capacitor having either a resistor or a voltage controlled discharge device connected in parallel therewith.
Preferably, the capacitor is non-linear, for example voltage dependent such that its capacitance reduces with increases in applied voltage. The capacitor may be temperature dependent such that its capacitance reduces with increases in operating temperature.
The resistor may be non-linear, for example voltage dependent such that its resistance decreases with increases in applied voltage.
In embodiments having a temperature dependent capacitor and a parallel resistor, the resistor may be positioned such that heat generated in the resistor is transferred to the capacitor.
A diode may be connected in series with the capacitor.
A circuit in accordance with the present invention may be connected in series with a spark plug of an internal combustion engine. Where that spark plug is energised from a distributor, the circuit may be connected either between the distributor and the respective spark plug or between a source of electrical energy such as a coil and the distributor.
In a system in which two or more spark plugs are to be energised from one source, then a respective circuit may be connected in series with each spark plug. For example, in an internal combustion engine with two spark plugs per cylinder, this arrangement would circumvent the need for dual ignition drives.
A circuit in accordance with the invention may also be used to enhance spark performance by connecting such a circuit between a high tension lead connected to a spark plug and a source of fixed potential. With such an arrangement a fuse is preferably connected in series with the capacitor such that if the capacitor or any component in parallel with the capacitor fails to a low impedance conductive condition the fuse will burn out and render the circuit ineffective without disabling the spark plug to which it is connected.
Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic illustration of a conventional electrical ignition system for a four cylinder combustion engine;
FIG. 2 illustrates a current versus time waveform for a spark generated by a conventional circuit of the type illustrated in FIG. 1.
FIG. 3 is a general circuit diagram illustrating components which can be combined in a variety of c
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Patent Abstract of Japan, vol. 9, No. 70 (M-367) (1793) Mar. 30, 1985, of JP-A-59-201,978, Nov. 15, 1984, Nippon Denso K.K.
Cross E. Rollins
Dawson Royalties Limited
Hinds William R.
Moulis Thomas
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