JP2000357578A - Spark plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spark plug improving its igniting capability to the maximum with respect to lean fuel. SOLUTION: An outer electrode 6 and a plug body 8 are separately formed, and the outer electrode 6 is arranged in a combustion chamber 4 in such a direction as is orthogonal to the direction from an intake valve side to an exhaust valve side in the combustion chamber 4. With this construction, because the outer electrode 6 formed in the combustion chamber 4 is arranged always in the direction not preventing the flow of an air-fuel mixture in the combustion chamber 4 regardless of the mounting angle/position around the axis of the plug body 8, it is possible to improve the igniting capability of the spark plug 1 to the maximum with respect to lean fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark plug for an internal combustion engine, and more particularly to a spark plug for improving ignitability.

[0002]

2. Description of the Related Art In general, in an internal combustion engine, an air-fuel mixture sucked and compressed into a combustion chamber is ignited by an ignition plug. As shown in FIG.
02, insulator 103, center electrode 104, outer electrode 105
And a mounting bracket 106 and the like, and applies a high voltage supplied from an ignition coil 107 (FIG. 5) to the combustion chamber 10.
8, a spark discharge is generated in a discharge gap formed by the center electrode 104 and the outer electrode 105 protruding into the combustion chamber 108, so that the mixture in the combustion chamber 108 is ignited. The ignition timing of the ignition plug 101 is always controlled to an optimum ignition timing by an ignition timing control means (not shown).

[0003] The spark plug 101 is required to have good ignitability for the purpose of purifying the exhaust gas of the engine and reducing fuel consumption. In particular, in recent years, high performance ignitability for lean fuel has been demanded. It is generally known that the larger the gap between the electrodes, the thinner the electrodes, and the smaller the area of the opposing electrodes, the better the ignitability in each case. It is known that the ignitability also changes depending on the mounting angle position of the outer electrode 105 inside the combustion chamber 108. As shown in FIG. 6, the outer electrode 105 moves from the intake valve 109 side to the exhaust valve 110 side. Direction of the spark plug 10
It is known from experimental data and the like that the ignitability can be improved by adjusting the mounting angle position of No. 1.

Therefore, the center electrode 104 and the outer electrode 105
A fixing member (not shown) attached to the cylinder head 112 and supporting the plug body 111 so as to adjust the angle about the axis of the plug body 111; A connecting member (not shown) for connecting and fixing the plug body 111 and a fixing member (not shown) while fixing the 111 at a predetermined rotation angle position
The plug body 111 is fixed at a predetermined rotation angle position and fixed to a fixing member (not shown) so that the outer electrode 105 is oriented in a predetermined direction inside the combustion chamber 108, so that the ignitability is improved. Is disclosed in Japanese Patent Laid-Open No. 9-219272.

However, in the spark plug 101 having a structure in which the plug main body 111 is fixed at a predetermined angular position and the outer electrode 105 is directed in a predetermined direction, when the plug main body 111 is mounted, the plug main body 111 is positioned at the predetermined angular position. In addition, the plug body 111 is fixed by tightening a fixing nut (not shown) screwed to a fixing member (not shown) while maintaining the angular position, so that the work of mounting the ignition plug 101 becomes complicated. As a result, production efficiency has been reduced. In addition, when the user replaces the spark plug 101 by himself, the plug body 111 may be fixed to a fixing member (not shown) without adjusting the position of the plug main body 111 to a predetermined angular position. In addition to not being able to obtain ignition performance, when using a lean fuel, the outer electrode 1
Since the fuel gas mixture 05 prevents the flow of the air-fuel mixture inside the combustion chamber 108, the combustion state of the air-fuel mixture may be abnormal and the performance of the engine may be significantly reduced.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances. By providing an outer electrode inside a combustion chamber separately from a plug body, the orientation of the outer electrode inside the combustion chamber can be improved. To provide a spark plug that maximizes ignitability with respect to lean fuel in a predetermined direction.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a center electrode and an outer electrode are protruded into a combustion chamber and supplied from an ignition coil. In a spark plug of an internal combustion engine that ignites the compressed mixed gas inside the combustion chamber by introducing a high voltage into the combustion chamber and causing a spark discharge in a discharge gap between the center electrode and the outer electrode, the ignition plug It is characterized in that it is formed separately from the plug body and the outer electrode is disposed inside the combustion chamber.

With this configuration, the outer electrode is formed separately from the plug main body inside the combustion chamber, so that the outer electrode is oriented in a predetermined direction regardless of the mounting angle position of the plug main body around the axis. be able to.

In the invention according to a second aspect of the present invention, the outer electrode is provided with a center electrode projecting into the combustion chamber by attaching the plug body to an ignition plug connection hole formed in the cylinder head. It is characterized in that it is formed to have a gap.

[0010] With this configuration, by attaching the plug body to the ignition plug connection hole formed in the cylinder head, the center electrode protruding into the combustion chamber and the outer electrode provided in the combustion chamber can be formed. A desired discharge gap can be formed.

According to a third aspect of the present invention, the outer electrode is formed by a substantially L-shaped electrode member, and the outer electrode is moved in a direction from the intake valve side to the exhaust valve side of the combustion chamber. It is characterized by being provided in a direction orthogonal to the direction.

With this configuration, the direction of the outer electrode in the combustion chamber is always changed from the intake valve side to the exhaust valve side without adjusting the mounting angle of the plug body around the axis. It is possible to maximize the ignitability in the direction perpendicular to the direction.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. First, the outline of the ignition plug will be described. As shown in FIGS. 1 and 2, the ignition plug is attached to an ignition plug connection hole 3 provided in a cylinder head 2 by projecting a center electrode 5 and an outer electrode 6 into a combustion chamber 4, and an ignition plug is provided. The high voltage supplied from the coil 7 is guided to the combustion chamber 4 to generate a spark discharge in a discharge gap formed by the center electrode 5 and the outer electrode 6, so that the air-fuel mixture sucked and compressed into the combustion chamber 4 It is structured to ignite.

Next, the spark plug 1 of the present embodiment will be described in detail. As shown in FIG. 1, the spark plug 1 of the present embodiment is formed by a plug body 8 and an outer electrode 6 provided in the cylinder head 2, and is provided in a spark plug connection hole 3 formed in the cylinder head 2. By attaching the plug main body 8, the center electrode 5 provided at the axial center portion of the plug main body 8 and the outer electrode 6 provided inside the combustion chamber 4 face each other at a predetermined interval. I have.

As shown in FIG. 1, the plug body 8 includes a center electrode 5 formed at an axial center portion of the plug body 8 and connected to the terminal 9, and an insulator 10 covering the outer periphery of the center electrode 5.
And a screw portion 11 formed on the outer peripheral portion to be screwed into the ignition plug connection hole 3 of the cylinder head 2.
Metal shell 1 formed with nut portion 12 for tightening
3, the plug body 8 is formed by fitting the insulator 10 including the center electrode 5 to the metal shell 13.

The outer electrode 6 is, as shown in FIG.
It is formed of an alloy having a substantially L-shape, one end of which is press-fitted into the cylinder head 2 to be provided inside the combustion chamber 4, and the plug body 8 is attached to the ignition plug connection hole 3 of the cylinder head 2. The outer electrode 6 is arranged so as to have a predetermined distance from the center electrode 5 protruding into the combustion chamber 4, and the outer electrode 6 is moved from the intake valve 14 side of the combustion chamber 4 to the exhaust valve as shown in FIG. It is provided in a direction orthogonal to the direction toward the 15 side (the direction of arrow A in FIG. 3). In FIG. 3, the outer electrode 6 is formed so as to face the left direction. However, the outer electrode 6 is directed from the intake valve 14 side to the exhaust valve 15 side of the combustion chamber 4 (arrow in FIG. 3). If it is a direction orthogonal to (A direction), it may be formed toward the right direction in FIG. Also,
The structure for attaching the outer electrode 6 to the cylinder head 2 is not limited to press-fitting the outer electrode 6 into the cylinder head 2 as long as the outer electrode 6 is formed inside the combustion chamber 4 and functions as a ground electrode. For example, the outer electrode 6 may be formed integrally with the cylinder head 2.

The operation of the ignition plug 1 according to the present embodiment in such a configuration will be described. As shown in FIG. 1, a screw portion 11 formed on a metal shell 13 of the plug body 8 is screwed into an ignition plug connection hole 3 formed on the cylinder head 2, and a nut 12 formed on the metal shell 13 is formed. Is tightened with a predetermined torque, so that the center electrode 5 protruding into the combustion chamber 4 is directed in a direction orthogonal to the direction of the combustion chamber 4 from the intake valve 14 side to the exhaust valve 15 side. And the outer electrode 6 formed at a predetermined interval.

Therefore, the spark plug 1 of the present embodiment
According to this, the outer electrode 6 is formed separately from the plug body 8, and the outer electrode 6 is formed from the intake valve 14 side of the combustion chamber 4 to the exhaust valve 1.
Since the outer electrode 6 is formed so as to be oriented at a predetermined distance from the center electrode 5 protruding into the combustion chamber 4 while being directed in a direction orthogonal to the direction toward the side 5, a complicated plug body 8 is formed. The outer electrode 6 inside the combustion chamber 4 can always be oriented in a fixed direction without adjusting the mounting angle about the axis of the shaft. As a result, in order to avoid the occurrence of knocking due to a high compression ratio when a lean fuel is used, a turbulence is generated in the air-fuel mixture by using swirl or tumble to increase the combustion speed. The ignitability of the spark plug 1 can be improved by preventing the air flow from being hindered, and the ignitability for lean fuel can be maximized.

[0019]

According to the first aspect of the present invention, the outer electrode is formed separately from the plug body, and the outer electrode is disposed inside the combustion chamber. Improving the ignitability of the ignition plug by forming the direction of the outer electrode in the combustion chamber so as not to hinder the flow of the air-fuel mixture in the combustion chamber without adjusting the surrounding mounting angle position Thus, the ignitability for lean fuel can be maximized.

According to the second aspect of the present invention, the plug body is attached to the ignition plug connection hole formed in the cylinder head so that the center electrode protruding into the combustion chamber is provided with a predetermined gap. Since the outer electrode is formed so as to have a discharge gap, a discharge gap is formed between the center electrode and the outer electrode, and the mixture in the combustion chamber can be ignited.

According to the third aspect of the present invention, the outer electrode is provided in a direction orthogonal to the direction from the intake valve side to the exhaust valve side of the combustion chamber.
The outer electrode can be prevented from obstructing the flow of the air-fuel mixture inside the combustion chamber, the ignitability of the spark plug can be improved, and the ignitability for lean fuel can be maximized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a spark plug according to an embodiment.

FIG. 2 is an explanatory view showing a state in which the spark plug of the present embodiment is attached to a cylinder head.

FIG. 3 is a view of the spark plug of the present embodiment as viewed from the inside of a combustion chamber.

FIG. 4 is an explanatory view showing a conventional spark plug.

FIG. 5 is an explanatory view showing a state in which a conventional spark plug is attached to a cylinder head.

FIG. 6 is a diagram showing the relationship between the direction of an outer electrode inside a combustion chamber and the ignitability of a spark plug.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spark plug 2 Cylinder head 3 Spark plug connection hole 4 Combustion chamber 5 Center electrode 6 Outer electrode 7 Ignition coil 8 Plug body 14 Intake valve 15 Exhaust valve

Claims (3)

[Claims] 1. A center electrode and an outer electrode projecting into a combustion chamber to guide a high voltage supplied from an ignition coil to a combustion chamber, thereby causing a spark discharge in a discharge gap between the center electrode and the outer electrode. Thereby, in the ignition plug of the internal combustion engine that ignites the compressed mixed gas inside the combustion chamber, the ignition plug has the outer electrode formed separately from the plug body, and the outer electrode is disposed inside the combustion chamber. A spark plug characterized by: 2. The outer electrode is formed to have a predetermined gap with the center electrode protruding into the combustion chamber by attaching the plug body to a spark plug connection hole formed in a cylinder head. Claim 1 characterized by the following:
The spark plug according to 1. 3. The outer electrode is formed of a substantially L-shaped electrode member, and the electrode member is provided in a direction orthogonal to a direction from the intake valve side to the exhaust valve side of the combustion chamber. The spark plug according to claim 1 or 2, wherein: