Patent GB-1512053-A (GB)
Title: Internal combustion engines
IPC: F02B19/12
Filed: 1975-07-02
Abstract: 1512053 Treating IC engine charges TOKAI TRW & CO Ltd 2 July 1975 [8 July 1974] 27861/75 Heading F1B An I.C. engine has a main combustion chamber for receiving an air-fuel mixture and an auxiliary combustion chamber in fluid communication with the main chamber, via an opening through which the air-fuel mixture can flow, and a spark -plug for igniting an air/fuel mixture in the auxiliary combustion chamber, the plug including first and second electrodes exposed to the interior of the auxiliary chamber and between which an electric arc passes to ignite the air/fuel mixture in the auxiliary chamber, and means for establishing an electrostatic field adjacent the first and second electrodes to promote the accumulation of fuel particles adjacent the first and second electrodes, said means including a third electrode spaced from the wall of the auxiliary chamber and means for establishing an electric potential between the first and third electrodes. The main combustion chamber 14 of engine 10 is connected to auxiliary combustion chamber 26 by passage 24. The cylinder is filled with a leaner-than-stoichiometric mixture during the intake stroke and some of this mixture flows through passage 24 during the compression stroke. Spark-plug 30 includes a central insulated electrode 32, an earth electrode 34 and an annular field electrode 40, the axis of which is co-linear with the axes of electrode 32 and passage 24. During the compression stroke a negative potential of about 8,000 volts is applied to electrode 32 and produces a corona discharge to electrode 40 which charges fuel particles entering through passage 24 and causes acceleration of the air-fuel mixture towards and past electrode 40. The fuel particles are electrostatically atomized and scattered outwardly against the inner surface 50 of the auxiliary combustion chamber and accumulate to form a rich mixture adjacent spark gap 36. At the end of the compression stroke the negative potential is increased to about 25,000 volts and a spark is produced between electrodes 32 and 34 which ignites the mixture in auxiliary chamber 26. A flame jet issues from passage 24 and ignites the lean mixture in the main combustion chamber. The 25,000 volt potential is provided by a conventional coil and connected to the appropirate spark plug of a multi-cylinder engine by the rotor arm of a distributer. The 8,000 volt potential is produced by a separate circuit and is applied continuously to the rotor arm so that as the rotor arm approaches each contact of the distributer during the compression stroke of a piston, the negative potential is applied to the appropriate spark-plug. In a modification, Fig. 5 (not shown) the internal surface of the auxiliary chamber is lined with a heat-resistive electrically-insulating ceramic layer, which becomes charged to the same potential as the electrode 32, so that fuel particles are repelled towards electrodes 34 and 40. In a second modification, Fig. 6, the insulating layer 20b covers only part of the surface and the exposed surface 112 attracts fuel particles. A modified construction, Fig. 7 includes a sparkplug having three electrodes 32c, 34c and 40c and which is screwed into a threaded collar forming part of auxiliary combustion chamber 26 which in turn is threaded into the engine cylinder head. In this construction, the auxiliary chamber is cooled by the fluid used to cool the cylinder head. In a further modification the electrode 32 is not pointed as in the previously described constructions, but has a rounded end and electrode 40 has a number of inwardly directed prongs.