JP2000235885A - Spark plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure ignition by forming an optimum flame kernel in an engine of the type having a high-speed flow in a combustion chamber. SOLUTION: This spark plug is equipped with a casing 60, an insulation leg part 20 mounted in the casing, a center electrode 10 guided through the insulation leg part and projecting from an end of the insulation leg part, an earth electrode 50 mounted on the casing, and a shielding device 100 connected to the earth electrode, and the shielding device is made up so as to form a spark gap F1 bordering the center electrode 10 and to shield the spark gap F1 against a flow in the axial direction or a flow in the radial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a casing, an insulating foot mounted on the casing, a central electrode guided through the insulating foot and projecting at the tip of the insulating foot, and an earth mounted on the casing. The present invention relates to a spark plug provided with an electrode.

[0002]

BACKGROUND OF THE INVENTION Although applicable to any spark plug, the present invention and the problems associated therewith are limited to spark plugs mounted on a cylinder block for engines of an Otto engine of a motor vehicle.

Generally, the spark plug reliably ignites the air / fuel mixture present in the combustion chamber of each cylinder of the Otto engine at each combustion cycle.
Thus, it is necessary, for example, to avoid ignition mistakes that can adversely affect the catalyst.

[0004] The present invention provides a method which, when the flow velocity is relatively high and the mixture is non-uniform, ensures that in general spark plugs and especially in certain combustion chambers (in short, for example, injection valves directed to spark plugs). It is based on the problem that proper flame nucleation is no longer guaranteed.

[0005] When the flow velocity in the combustion chamber is high, the spark of a general spark plug is generated because an electric plasma composed of an ionized gas portion is entrained by gas motion.
During the combustion period, the transition occurs far from the electrode region. If the flow velocity is 5 m / s directed radially, that is, perpendicular to the axis of the spark plug, and perpendicular to its electrode, the spark displaces about 5 mm after 1 ms.

At higher flow velocities, for example 30 m / s, the spark is stripped after a few millimeters of displacement and is ignited again between the electrodes. This process may be repeated multiple times. The energy in the plasma is then distributed to such a large gas volume that it can no longer be hot enough to ignite.

The flow velocity in the electrode area is 1 m / s to 5 m /
s, so that if the spark is not stripped and the energy of the plasma is capable of igniting as large a volume as possible, the ignition capability of the spark is optimal.

[0008]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to create a spark plug geometry which protects the area of the electrical ignition spark from too high a flow rate of the gas mixture.

[0009]

According to the present invention, there is provided, in accordance with the invention, a spark plug of the type described at the outset, comprising a shielding device coupled to a ground electrode as claimed in claim 1 or 6 or 9. Wherein the shielding device forms a spark gap with respect to the central electrode to shield the spark gap against axial and / or radial flow so that the ground electrode or the ground electrode is at least partially The center electrode extending beyond the insulating foot is axially retracted with respect to the center electrode so as to form a spark gap, and the ground electrode and the insulating foot are formed cylindrically symmetrically. As a result, the acting radial flow can transfer the spark gap to the shadow side of the flow, or the earth electrode is axially forward with respect to the center electrode. And the insulating foot is drawn forward in the axial direction with respect to the central electrode, and sparks against the central electrode extending at least partially beyond the inner surface of the forwardly drawn insulating foot. A gap can be formed and the ground electrode and the insulating foot are formed cylindrically symmetrically, so that the spark gap is shielded against the acting radial flow, which is solved in each case. .

[0010]

An advantage of the present invention is that, in comparison with the known solution, a reliable ignition is possible with optimum flame nucleation in engines of the type with a high flow velocity in the combustion chamber.

The idea underlying the invention consists in providing a means for shielding against extremely high flow velocities in the combustion chamber. This allows the spark to be optimally ignited because it remains within the medium flow range and thus does not significantly reduce its energy.

[0012] Advantageous configurations of the invention are described in the further claims.

In a preferred embodiment of the invention, the spark plug has a grounding element as an earthing electrode, in which the shielding device is integrated. This suffices to simply change the ground bending member under the conventional concept.

In another preferred embodiment, the shielding device has the shape of a cup, in which case a finger is provided inside the cup as a ground electrode tip. This shields the spark gap, especially against axial flow.

In a further advantageous embodiment, the shielding device can be screwed on the ground electrode. This allows
It is possible to adapt the spark plug to the characteristics of the respective combustion chamber or the respective engine type.

In a further advantageous embodiment, the shielding device is formed cylindrical to shield the spark gap against radial flow.

In a further advantageous embodiment, the ground electrode is axially oriented relative to the central electrode so that the ground electrode forms a spark gap with the central electrode projecting at least partially beyond the insulating foot. I'm withdrawn. In this case, it is advantageous if the ground electrode and the insulating foot are advantageously cylindrically symmetrical, so that the acting radial flow can transfer the spark gap to the shadow side of the flow.

In a further preferred embodiment, the ground electrode has an axially extending slit.

In a further advantageous embodiment, the ground electrode has one or more fingers in the region situated opposite the center electrode, the finger being directed towards the center electrode.

In a further advantageous embodiment, the ground electrode is drawn axially forward with respect to the central electrode,
Further, the insulating foot is drawn forward in the axial direction with respect to the center electrode. In that case, a spark gap can be formed for the central electrode, which extends at least partially beyond the inner surface of the insulating foot that has been drawn forward. The ground electrode and the insulating foot are cylindrically symmetrical, so that the spark gap is shielded from the acting radial flow.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings.

The drawing shows only those parts of the spark plug according to the embodiment which are important to the invention, while the other parts are omitted for the sake of clarity of the drawing.

FIG. 1 is a schematic cross sectional view of a spark plug according to a first embodiment of the present invention.

The spark plug according to the first embodiment includes a casing 60, an insulating foot 20 attached to the casing 60, and a central electrode 1 guided through the insulating foot 20.
0, and the center electrode 10 protrudes at the tip of the insulating foot.

A ground electrode 50 is provided on the casing 60, and a shielding device 100 is connected to the ground electrode 50. The shielding device 100 forms a spark gap F1 with respect to the center electrode 10 to form a spark gap F1. The spark gap F1 is formed so as to shield the axial flow Vp.

The spark plug has a grounding member as a ground electrode, and the shielding device 10 is integrated in the grounding member.
Has a cup shape, and in that case, a finger 120 is provided inside the cup as a tip of a ground electrode.

FIG. 2 is a schematic sectional view showing a spark plug according to a second embodiment of the present invention in a longitudinal section.

The spark plug of the second embodiment is likewise guided by a casing 60 ', an insulating foot 20' attached to the casing 60 ', and the insulating foot 20' and projecting at the tip of the insulating foot. Central electrode 10 '.

The casing 60 'is provided with an earth electrode 50', and the earth electrode 50 'is provided with a shielding device 200.
The shielding device forms a spark gap F1 'with respect to the center electrode 10' and is configured to shield this spark gap F1 'against the radial flow Vs. An advantageously cylindrical shielding device 200 can be screwed onto the ground electrode 50 '.

FIG. 3 is a longitudinal sectional view schematically showing a part of a spark plug according to a third embodiment of the present invention.

The spark plug according to the third embodiment is guided through the casing 60 '', the insulating foot 20 '' attached to the casing 60 '', and the insulating foot 20 '', and is provided at the tip of the insulating foot. By the way, the protruding central electrode 1
0 '' and a ground electrode 50 '' attached to the casing 60 ''.

In this embodiment, no additional shielding is provided; rather, the ground electrode 50 "is connected to the central electrode 1 extending at least partially beyond the insulating foot 20".
It is axially retracted with respect to the center electrode 10 '' so as to form a spark gap F1 '' with respect to 0 ''.

In this case, the ground electrode 50 ″ and the insulating foot 20 ″ are formed cylindrically symmetrically, so that the acting radial flow Vs is reduced by the spark gap F
1 '' can be transferred to the shadow side of the flow. In other words, the spark flies downwind.

Additionally, in this embodiment, the ground electrode 5
It is possible that 0 '' has an axially extending slit.

FIG. 4 is a schematic cross-sectional view of a spark plug according to a fourth embodiment of the present invention.

In the fourth embodiment, the ground electrode 50 '''
Corresponds to the third embodiment, except that it has one or more fingers 70 '''directed at the central electrode 10''' in a region located opposite its central electrode 10 '''. . Also in this embodiment, it is possible for the ground electrode 50 "" to have an axially extending slit.

FIG. 5 is a schematic cross-sectional view of a spark plug according to a fifth embodiment of the present invention.

The spark plug according to the fifth embodiment comprises a casing 60 ''''', an insulating foot 20''''' attached to the casing 60 ''''', and an insulating foot 2''.
Central electrode 10 "" guided through 0 """
And a ground electrode 50 ′ ″ ″ attached to the casing 60 ′ ″ ″.

The ground electrode 50 '"" is extended axially forward of the central electrode 10 "", and the insulating foot is extended axially forward of the central electrode 10 "'". Have been.

The insulating foot portion 20 "" which is drawn forward.
Central electrode 1 extending at least partially beyond the inner surface of
A spark gap F1 "" can be formed for 0 "". Earth electrode 50 "" and insulating foot 2
0 ′ ″ ″ is cylindrically symmetric, so that
The spark gap F1 "" is shielded against the acting radial flow Vs.

The invention described above with reference to the preferred embodiments is not limited to these embodiments, but rather can be varied in various forms.

In particular, the shape of the shielding device can be adapted to the respective flow characteristics in the combustion chamber.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a spark plug according to a first embodiment of the present invention in a longitudinal section.

FIG. 2 is a schematic cross-sectional view of a spark plug according to a second embodiment of the present invention in a longitudinal section.

FIG. 3 is a schematic cross-sectional view of a portion of a spark plug according to a third embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a spark plug according to a fourth embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of a spark plug according to a fifth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10 center electrode, 20 leading edge foot, 50 ground electrode, 60 casing, 100 shielding device, 7
0 "", 120 fingers, Vp axial flow,
Vs Radial flow

Claims (9)

[Claims] 1. A spark plug, comprising: a casing (60, 60 '); and an insulating foot (20, 20') attached to the casing (60, 60 '). Central electrode (10, 10 ') guided through the section (20, 20') and projecting at the tip of the insulating foot
A shielding electrode (50, 50 ') provided on the casing (60, 60'), and a shielding device (100, 20 ') coupled to the ground electrode (50, 50').
0) is provided and the shielding device is provided with a spark gap (F1, F2) with respect to the central electrode (10, 10 ').
1 ′) and the spark gap (F1, F1 ′)
Characterized in that it shields against axial and / or radial flows (Vs, Vp). 2. The spark plug is connected to a ground electrode (50, 5).
0 ′) has an earth bending member, in which the shielding device (100) is integrated.
The spark plug according to claim 1. 3. The spark plug according to claim 1, wherein the shielding device (100) has a cup shape, and a finger (120) is provided inside the cup as a tip of a ground electrode. 4. The shielding device (100, 200) is screwable onto a ground electrode (50, 50 ').
The spark plug according to any one of claims 1 to 3. 5. The shielding device (200) is cylindrically shaped for shielding against radial flow.
The described spark plug. 6. A casing (6) for a spark plug.
0 ", 60""), and insulating feet (20", 20 "") provided on the casing (60 ", 60""). The center electrode (1) guided through the foot (20 '', 20 '''') and protruding at the tip of the insulating foot.
0 ", 10""), and ground electrodes (50", 50 "") attached to the casing (60 ", 60""). The ground electrodes (50 ", 50") are at least partially extended beyond the insulating feet (20 ", 20"") to the center electrodes (10", 10 ""). To form a spark gap (F1 '', F1 '''') with respect to the center electrode (10 '', 10 '''') in the axial direction, and a ground electrode (50 '', 5 '').
0 "") and the insulating feet (20 ", 20"") are formed cylindrically symmetrically, so that the acting radial flow is reduced by the spark gaps (F1", F1 ""). ) Can be transferred to the shadow side of the flow. 7. A spark plug according to claim 6, wherein the ground electrode has a slit extending in the axial direction. 8. One or more fingers (7) facing the central electrode (10 '''') in an area where the ground electrode (50 '''') is located opposite the central electrode (10 '''').
8. The spark plug according to claim 7, wherein the spark plug has 0 '''). 9. A spark plug, comprising: a casing (60 ""); and an insulating foot (20 "") attached to the casing (60 ""). A central electrode (10 "") guided through an insulating foot (20 "") is provided, and a ground electrode (50 "") mounted on the casing (60 ""). In this case, the ground electrode (50 "") is connected to the center electrode (1).
0 ''''') is drawn forward in the axial direction, and the insulating foot is drawn forward in the axial direction with respect to the center electrode (10'''') and is drawn forward. The central electrode (1) extends at least partially beyond the inner surface of the insulating foot (20 '''').
0 ""), a spark gap (F1 "") can be formed, and the ground electrode (50 "") and the insulating foot (20 "") are cylindrically symmetric. A spark plug characterized in that it is formed so that the spark gap (F1 "") is shielded from the acting radial flow.