US 4,613,789 AGranted

Spark plug with capacitor spark discharge

AssigneeRobert Bosch GmbH

InventorsWerner Herden, Werner Bloss

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Abstract

A spark plug which has a capacitor located therein, connected in parallel to the main or ignition spark gap (13), additional includes a pilot or pre-spark gap (12) located within the insulator (18) of the spark gap, to control discharge of the capacitor (14) through the main spark gap (13). In accordance with the invention, the pre-spark gap (12) is located within a chamber (34) in the insulator which is filled with a pressurized gas, preferably nitrogen under pressure of between 2 to 100 bar, preferably 5 to 30 bar, with the electrodes (27, 27) defining the pre-spark gap being spaced, preferably, between about 0.1 to 1 mm from each other. Placing the pre-spark gap electrodes within a pressurized gas chamber increases the energy available at the main spark gap (13) for ignition even of very lean fuel-air mixtures. Preferably, an inductive-resistive circuit (15) is connected in shunt across the main electrode (13) to prevent arcing and glow discharges across the main spark gap (13) after the initial ignition spark.

Claims19

Dependent claims

Spark plug for combination with an Otto-type internal combustion engine having

a head or connecting end and a spark end;
a metal housing (19);
an insulator (18) located within the metal housing and formed with a central opening therein;
an externally accessible high-voltage terminal (11, 24, 24') sealed into the insulator;
a central electrode (26) centrally located within the insulator, projecting from the insulator at an end remote from the externally accessible terminal and defining an ignition spark gap (13) with a counter electrode (30) secured to the metal housing;
a capacitor (14) located within the insulator and electrically connected in parallel to said ignition spark gap and dischargeable over said ignition spark gap (13);
a pilot or pre-discharge spark gap (12) located within the insulator and controlling discharge of the capacitor;
wherein
the insulator comprises
a two-part insulator structure having an end part portion (20) adjacent the spark end and a head part portion (21) adjacent the head end, said portions fitting telescopically within each other and being, respectively, dimensioned to leave a space therebetween defining a chamber (34);
said capacitor (14) and said pilot or pre-discharge spark gap (12) are located within said chamber;
and
said chamber is filled with a pressurized gas, to place the pilot or pre-spark gap (12) within a space subject to gas under elevated pressure.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/671,555Filed 15 Nov 1984
Priority: DE 334702724 Dec 1983
Granted: 23 Sep 1986
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

F02P 13/00
Sparking plugs structurally combined with other parts of internal-combustion engines
F02P 3/0823
Closing the discharge circuit of the storage capacitor with electronic switching means: with electronic tubes
F02P 9/002
Electric spark ignition control, not otherwise provided for: control of spark intensity, intensifying, lengthening, suppression
H01T 13/465
In series connection: one spark gap being incorporated in the sparking plug