JPH11324678A - Ignitor for gasoline engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignitor for a gasoline engine which reduces the distance between the discharge position of an ignition plug and end gas in an inlet valve side without shortening the diameter of the inlet valve. SOLUTION: An ignition plug 9 is arranged in the center of inlet valves 7a, 7b and exhaust valves 8a, 8b and the inlet valves 7a, 7b have diameter larger than that of the exhaust valves 8a, 8b so that the central axis PX of the ignition plug 9 is offset from the center CX of a combustion chamber 4 to the exhaust valves 8a, 8b side. A central electrode 10 of the ignition plug 9 is offset from the central axis PX of the ignition plug 9 to the suction values 7a, 7b side and electricity is discharged toward an earth electrode 11 extended from the exhaust valves side. The electricity is discharged in a position of SX expressed by an X mark to offset to the inlet valves by D in a figure so that the distance of the end gas in the inlet valves side is shortened by the D to improve the antiknock property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ignition device for a gasoline engine.

[0002]

2. Description of the Related Art In order to prevent knocking of a gasoline engine, it is desirable to reduce a distance between a discharge position of an ignition plug and an end gas. In particular, since the temperature of the end gas on the intake valve side is lower than that of the end gas on the exhaust valve side, it is desirable to reduce the distance from the end gas on the intake valve side. From such a viewpoint, Japanese Utility Model Laid-Open Publication No. 2-69024 discloses that an ignition plug is offsetly arranged on an intake valve side.

[0003]

The apparatus disclosed in the above publication is described in an engine having three intake valves, so that the spark plug can be offset without reducing the intake valve diameter. However, in the case where one or two intake valves are currently used in many cases, if an offset arrangement is to be made on the intake valve side, the diameter of the intake valve must be reduced, resulting in a decrease in output. The present invention has been made in view of the above problems, and has as its object to provide an ignition device for a gasoline engine that can reduce the distance between an end gas on the intake valve side and the discharge position of the ignition plug without reducing the diameter of the intake valve.

[0004]

According to the first aspect of the present invention, the center electrode is disposed off the center axis of the spark plug,
An ignition device for a gasoline engine is provided, wherein an ignition plug is formed so as to be eccentrically discharged, and the ignition plug is mounted such that the position of the eccentric discharge is on the intake valve side. In the ignition device configured as described above, the discharge is performed when the ignition plug is eccentric to the intake valve side from the center axis of the ignition plug.

According to a second aspect of the present invention, there is provided an igniter according to the first aspect, wherein a ground electrode which is disposed opposite to the center electrode and performs a discharge in cooperation with the center electrode is formed radially outside the center electrode. Provided. In the igniter configured as described above, when the eccentricity is closer to the intake valve side than the center axis of the ignition plug, discharge is performed on the side of the center electrode.

According to a third aspect of the present invention, there is provided the ignition device according to the second aspect, wherein the ground electrode is provided on the cylinder head. In the ignition device configured as described above,
Discharge occurs between the center electrode eccentrically arranged on the intake valve side of the center axis of the spark plug and the ground electrode provided on the cylinder head. Then

According to a fourth aspect of the present invention, there is provided an ignition device in which when two intake valves are arranged in the first aspect of the invention, a center electrode is arranged on a center line between the intake valves. Is done. In the ignition device configured as described above, when two intake valves are arranged, discharge is performed on the center line between the intake valves and eccentric to the intake valve side with respect to the center axis of the ignition plug. .

According to a fifth aspect of the present invention, there is provided the ignition device according to the first aspect of the present invention, wherein the ignition plug is attached by the positioning means and the pressing means such that the eccentric discharge position is located on the intake valve side. In the ignition device configured as described above, the ignition plug is positioned so as to be discharged on the intake valve side by the positioning means and the pressing means.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a view of an embodiment of an ignition device according to the present invention as viewed from a piston side. A cylinder head 1 has a piston 3 (see FIG. 2) that slides in a cylinder bore 2 indicated by a dashed line. ), A combustion chamber 4 is formed. The edge of the squish surface 5 is indicated by 6. Two intake valves are arranged and indicated by 7a and 7b, and two exhaust valves are arranged and indicated by 8a and 8b.
The intake valves 7a, 7b have a larger diameter than the exhaust valves 8a, 8b.

A spark plug 9 is arranged at the center between the intake valves 7a, 7b and the exhaust valves 8a, 8b.
Since b has a larger diameter than the exhaust valves 8a and 8b, the central axis PX of the ignition plug 9 is offset toward the exhaust valve relative to the central axis CX of the combustion chamber 4. And
The center electrode 10 of the ignition plug 9 is arranged offset from the center axis PX to the intake valve side, and discharge is performed between the center electrode 10 and the ground electrode 11 extending from the exhaust valve side. As a result,
The discharge performed by the PX is changed to the S indicated by a cross.
It is performed at the position indicated by X (which happens to overlap with CX in this case), and is performed at the position closer to the intake valve by D in the figure, and the distance to the end gas on the intake valve side is correspondingly reduced. Shrinkage improves knock resistance.

FIG. 2 is a sectional view taken along line II-II of FIG. The spark plug 9 has a high-voltage conductor 12 connected to the center electrode 10 covered by a porcelain insulator 13. The insulator 12 is held by a metal housing 14.
A part of the piston 4 on the piston side is extended to form a ground electrode 11. The housing 14 has a flange 15, and the spark plug 9 is fixed by tightening a nut 18 on the bottom surface 17 of the plug mounting hole 16. The spark plug 9 moves the center electrode 10 to the intake valve side. Since it is necessary to position the plug, a convex portion 19 is formed on a part of the flange 15 and the convex portion 19 is aligned with a concave portion 20 formed on the bottom surface 17 of the plug mounting hole 16 to perform positioning.

FIG. 3 shows the structure of a spark plug 9 according to a second embodiment of the present invention in the same cross section as FIG. In the spark plug 9 according to the second embodiment, the ground electrode 11A is the ground electrode 1A according to the first embodiment.
Instead of extending from the exhaust valve side as in 1, the housing 14 is formed to extend toward the piston on the intake valve side. As a result, the discharge position SX is between the center electrode 10 and the ground electrode 11A on the side thereof, and the distance D1 between the central axis PX of the plug 9 and the discharge position SX is larger than in the first embodiment. Accordingly, the distance from the end gas on the intake valve side is further reduced, and knock resistance is further improved. In addition, with such a structure, the manufacture of the ground electrode is facilitated, and the cost of the spark plug 9 is reduced.

FIG. 4 shows the structure of a spark plug 9 according to a third embodiment of the present invention in the same cross section as FIG. In the spark plug 9 according to the third embodiment, the ground electrode 11B is formed on the cylinder head 1 side. With such a structure, it is not necessary to extend the housing 14 to the piston side, so that the center electrode can be brought closer to the cylinder head 1 side as shown by 10B, so that the center electrode PX The distance D2 between the discharge positions SX is larger than in the second embodiment, and the distance between the discharge position SX and the end gas on the intake valve side is further reduced, and knock resistance is further improved. In consideration of replacement, it is preferable to use an L-shaped bar 22 made of a material having good anti-corrosion properties, which fits into the groove 21 formed in the cylinder head 1 in consideration of replacement.

[0014]

According to the present invention, the distance between the discharge position of the ignition plug and the end gas on the intake valve side can be reduced without reducing the diameter of the intake valve, and the knock resistance is improved. be able to.

[Brief description of the drawings]

FIG. 1 is a view of a structure according to a first embodiment as viewed from a piston side.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a view of a structure according to a second embodiment, viewed in the same cross section as FIG. 2;

FIG. 4 is a view of the structure of the third embodiment as viewed in the same cross section as FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder head 2 ... Cylinder bore 3 ... Piston 4 ... Combustion chamber 7a, 7b ... Intake valve 8a, 8b ... Exhaust valve 9 ... Spark plug 10, 10B ... Central electrode 11, 11A, 11B ... Ground electrode 13 ... Insulator 14 ... Housing 15 ... Flange 18 ... Nut 19 ... Protrusion 20 ... Recess CX ... Center axis of combustion chamber PX ... Center axis of spark plug SX ... Discharge position

Claims (5)

[Claims] 1. A spark plug is formed such that a center electrode is disposed off a center axis of a spark plug, and the spark plug is eccentrically discharged.
An ignition device for a gasoline engine, wherein the ignition plug is mounted such that the position of the eccentric discharge is on the intake valve side. 2. The ignition device according to claim 1, wherein a ground electrode disposed to face the center electrode and performing a discharge in cooperation with the center electrode is formed radially outward of the center electrode. 3. The ignition device according to claim 2, wherein the ground electrode is provided on the cylinder head. 4. The ignition device according to claim 1, wherein when two intake valves are arranged, a center electrode is arranged on a center line between the intake valves. 5. The ignition device according to claim 1, wherein the spark plug is mounted by a positioning means and a pressing means so that an eccentric discharge position is located on an intake valve side.