SI9300324A - Spark plug - Google Patents

Abstract

A sparking plug for an internal combustion engine comprising a metal case (1) provided with a threaded part (9) for fixing the sparking plug into a cylinder head of the engine, and an insulator (2), placed in the metal case (1), having an end part (2a) which extends axially beyond the threaded part (9) of the metal case (1). In the insulator (2) there is placed a central electrode (3) and a terminal pin for the supply of a high voltage, conductively connected to the central electrode (3). At least one toroidal auxiliary electrode (8) is fixed along the periphery of the end part of the insulator (2).

Description

(57) A spark plug for an internal combustion machine comprises a metal housing fitted with a threaded part for attaching a spark plug to the cylinder head of the machine and an insulator mounted in a metal housing having an end portion extending axially across the threaded portion of the metal housing. The insulator houses a central high voltage power electrode and a connecting pole that is conductively connected to the central electrode. At least one toroidal auxiliary electrode is attached along the periphery of the end portion of the insulator.

S! 9300324 A

Bednar Jan

Spark plug

The invention relates to the construction of a spark plug for an internal combustion machine.

The prior art spark plugs consist of a metal housing fitted at one end with a thread for attaching a spark plug to the cylinder head of an internal combustion machine and further to a cylindrical insulating part which is axially inserted into a metal housing and serves to insulate high voltage conductors.

A cylindrical center electrode of cylindrical shape and a terminating stem is axially inserted into the insulator, which serves to supply high voltage to the central electrode and is typically sealed in the opening of the insulator with a special seal, which simultaneously provides a conductive connection between the central electrode and the termination stem.

A metal spark plug housing has a conductively and mechanically bonded earthing electrode, which is guided outwards into the combustion chamber of the machine, the active part of which is mounted above the central electrode.

In the case of a conventional spark plug having a simple earthing electrode, only one discharge occurs at a given point in time with a single spark determined by the construction of the spark plug.

This practically makes it impossible to use such spark plugs on machines that use very lean mixtures. Even if there is an insufficiently mixed mixture at a given moment of spark discharge, or some other circumstances that adversely affect combustion occur there, insufficient combustion will take place in the combustion chamber of the machine.

Insufficient combustion of the mixture is also caused by the position of the spark plug gap slot, which is completely zero or very slightly out of reach of the edge of the housing and therefore the mixture is ignited only along the wall of the combustion chamber. In this type of construction, spark discharge is focused on a small area of the central and ground electrodes.

This results in the shortening of the especially central electrode, which in fact has a negative effect on the life of the spark plug.

Further, spark plugs with multiple earthing electrodes are known. The most commonly used type contains two to three earthing electrodes that are welded to the thread end of the spark plug metal housing.

The ends of the earthing electrodes are then bent from the side toward the central electrode, where between the central electrode and each earthing electrode there is an identical spark plug slot corresponding to the spark plug slot for a given type of spark plug and machine.

Another type uses an earthing electrode made from one piece of conductive material with projections that are embossed into the end of the threaded portion of the metal housing, where each projection represents the active part of the earthing electrode.

However, these constructions do not have a pronounced effect on prolonging the life of spark plugs. Even when the end of the insulator or the gap of the spark plug becomes clogged with conductive material, the spark plug stops working and this fact cannot be changed even with a larger number of grounding electrodes. In addition, the manufacture of spark plugs with a large number of grounding electrodes is always associated with greater technological requirements.

Also known is the construction according to European Patent 430 899, which partially solves the problem of spark plug life. The outer end of the central electrode is in the form of a low cylinder. A circular grounding electrode, which has some, usually four projections, is imprinted on the end of the threaded portion of the metal housing of the spark plug. The projections are bent towards the edge of the central electrode, where, between the ends of the projections and the lower edge of the central electrode, a spark plug is provided, corresponding to the jump distance of the spark. Extension of life is caused by an increase in dimensions, that is, by an increase in the active periphery of the central electrode.

Another solution according to German patent no. 38 16 968 has a cone-shaped bore on the side of the central electrode in the insulator, which extends towards the end of the spark plug. The tapered bore is terminated at its open end by a ring-shaped grounding electrode. A central electrode is positioned along the entire length in the axis of the bore. This spark plug requires a lower voltage than the above-described constructions to produce a discharge spark, but other disadvantages remain.

The above disadvantages are eliminated by a spark plug for internal combustion machines comprising a metal housing fitted on one side with a thread to attach a spark plug to the cylinder head of the machine, further an insulator mounted in a metal housing such that the end of the insulator extends into the axial of the spark plug through a threaded portion of the metal housing, and a central electrode that is conductively coupled to a high-voltage supply end terminal, wherein at least one conductive or semiconducting toroidal auxiliary electrode is attached along the periphery of the end of the insulator.

A further object of the invention is a spark plug where a conductive ring-shaped earth electrode is attached to the threaded part of the housing and coaxially fitted with an insulator.

The spark plug of the invention may further be provided with a ring-shaped head mounted on top of a central electrode that axially extends beyond the end portion of the insulator.

In the basic type of a spark plug according to the invention, with one auxiliary electrode, a two-spark discharge occurs simultaneously along the entire periphery of the central auxiliary or ground electrode, thus always at the highest concentration points. In this regard, the probability of ignition of the mixture and its combustion is increased. The test runs confirmed the increase in power and flexibility of the machine. The life of this spark plug is extended two or three times because it is discharged along the entire periphery of the central, auxiliary and ground electrodes. In terms of function, this construction is reminiscent of a spark plug with a multiple earthing electrode, but with an incomparably larger number of locations where discharge can occur. A further advantage is the reduced technological complexity in the production of the spark plug housing, since either the earthing electrode is not required at all, especially in applications with low heat load, or is simple in both form and composition. Among the greatest advantages of the invention is the wide range of thermal values of the spark plug, that is, the same type of spark plug can be used for a very wide range of thermal loads.

In addition to the above advantages, the spark plug of the invention has the following advantages. The insulator tip with the auxiliary electrodes is substantially moved towards the center of the combustion chamber.

Because of the auxiliary electrodes, at the tip of the insulator, two or more sparks are discharged, spatially spaced, always at the places with the highest concentration of the mixture. In this way, the probability of ignition and its good combustion is significantly increased even with a very lean mixture. In the event that a single gap sparkles e.g. due to contamination not working, spark discharge can occur in at least one of the other slots according to the number of auxiliary electrodes.

The invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 and 2 examples of spark plugs showing partial cross sections without and with a grounding electrode,

FIG. 3 and 4 show a partial cross-section of a spark plug with two auxiliary electrodes without and with a grounding electrode,

Figures 5 and 6 show examples of spark plugs with a ring shaped head without and with a grounding electrode and

The SL 7 is an example of a spark plug with two auxiliary electrodes and a ring-shaped head.

The spark plug according to FIG. 1 consists of a metal housing 1 equipped with a thread 10 in which the insulator 2 is coaxially mounted and a central electrode 3 is further housed in the insulator, which is conductively connected by means of a special seal 7 to a termination pin 6 for supplying high voltage to the spark plug. On the electrode side, the insulator 2 extends with its end part 2a, and on the opposite clamping side of the spark plug, with its end part 2b axially through a metal housing 1. The end part 2a of insulator 2 is provided along its periphery with a toroidal auxiliary electrode 8. The electrical discharge then between the central electrode 3, the toroidal auxiliary electrode 8 and the inner edge 5 of the metal housing 1.

In FIG. 2 shows a spark plug equipped with a grounding electrode 4 formed by a metal ring that is conductively connected to the threaded portion 9 of the metal housing 1 of the spark plug.

In FIG. 3 and 4 show designs with two auxiliary electrodes 8 or without or with a grounding electrode 4. Between the central electrode 3 and the auxiliary electrode respectively. electrode 8 undergoes a creep discharge, while air is discharged between the lower auxiliary electrode 8 and the ground electrode 4.

In FIG. 5, 6 and 7 show different types of spark plugs with a ring-shaped head 11. The outer diameter of the ring-shaped head 11 of the central electrode 3 is always designed to be consistent with the outer diameter of the end part 2a of the insulator 2. High voltage requirements may be required. in production, they control the width of the spark gap between the auxiliary electrodes 8.

The spark plug according to the invention can be used in all types of spark ignition machines, especially in machines with a lean mixture.

For

Bednar Jan:

PATENT OFFICE

LJUBLJANA

Claims (3)

1. A spark plug for an internal combustion machine comprising a metal housing 1 equipped with a thread 10 for attaching a spark plug to the cylinder head of the machine and an insulator 2, which is housed in a metal housing 1 and extends axially through the threaded portion 9 of the housing 1 with its end part 2a, wherein a central electrode 3 is mounted on the insulator 2 and, on the other hand, a high-voltage supply connection pole 6 , which is conductively connected to the central electrode 3, which forms together with the inner edge 5 of the metal housing 1 a spark gap, characterized in that at least one toroidal auxiliary electrode (8) is attached along the periphery of the insulator end portion (2a). Spark plug according to claim 1, characterized in that a grounding electrode (4) of a circular shape is attached to the threaded part (9) of the housing (1) and is coaxially mounted within the insulator (2). Spark plug according to one of Claims 1 and 2, characterized in that the central electrode (3) is provided with a ring-shaped head (11) extending axially through the end portion (2a) of the insulator (2). For Bednar Jan: PATENT OFFICE LJUBLJANA Summary Spark plug The spark plug for an internal combustion machine comprises a metal housing fitted with a threaded part for attaching a spark plug to the cylinder head of the machine, and an insulator mounted in a metal housing having an end portion extending axially across the threaded portion of the metal housing. The insulator houses a central high voltage power electrode and a connecting pole that is conductively connected to the central electrode. At least one toroidal auxiliary electrode is attached along the periphery of the end portion of the insulator. 2α PATENT OFFICE LJUBLJANA PATEHTHA WRITER * « ΡΑΤΕΚΤΝΛ PISARNA