JP2520162Y2 - Position fixing structure for engine pressure sensor - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position fixing structure for an engine pressure sensor (hereinafter simply referred to as a pressure sensor) mounted between a cylinder head and a spark plug.

[0002]

2. Description of the Related Art Current engines sometimes have a donut-shaped pressure sensor interposed between a spark plug and a cylinder head. This pressure sensor is for measuring the pressure in the cylinder to detect the combustion state of the engine,
The built-in piezoelectric ceramic converts the pressure in the cylinder into an electric signal, and the electric signal is taken out by a lead wire. As a method of mounting this pressure sensor on the cylinder head together with the spark plug, first set the pressure sensor in the recess for mounting the spark plug, then insert the screw part of the spark plug into the center hole of the pressure sensor, and then In some cases, the plug may be tightened to the female screw in the recess with an impact wrench or the like.

[0003]

A drawback of the above-described conventional mounting method is that the lead wire of the pressure sensor is flexible until the pressure sensor is set in the recess and the ignition plug is inserted, so that the bow is bowed. It means that you will fall down in such a way that it will hinder your work. On the other hand, there is a wire groove with a semicircular cross section through which the lead wire of the pressure sensor is passed, on the inner wall of the recess, but this is merely for guiding the lead wire and does not have the function of eliminating the above-mentioned drawbacks. .

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention provides a position fixing structure for a pressure sensor having the following structure. A large diameter portion is formed on a part of the lead wire of the pressure sensor. The inner diameter of the lead wire is large enough to fit the large diameter portion of the lead wire, and the opening of the communicating portion with the recess is narrower than the large diameter portion of the lead wire and slightly wider than the non-large diameter portion. Form a wire groove. With the pressure sensor set in the recess, the large diameter portion of the lead wire is fitted and held in the wire groove.

[0005]

Function: The large diameter portion of the lead wire is fitted and held in the wire groove. Therefore, if the large diameter portion of the lead wire is fitted into the wire groove and the pressure sensor is set in the recess, the lead wire does not fall into the recess.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. The spark plug P is a well-known plug including a terminal nut 1, a corrugation 2, a hexagonal portion 3 of a metal shell, a body portion 4 of the metal shell, a screw portion 5, an electrode 6, and the like in this order from the top, and below the body portion 4. A gasket 7 is attached to the.

The pressure sensor S comprises a lead wire S attached to a donut-shaped sensor body S1 containing a piezoelectric ceramic.
2 is connected, and the threaded portion 5 of the ignition plug P is inserted into the center hole S3 in the middle. And the lead wire S
2 has a large diameter portion S2a made of rubber.

On the other hand, the cylinder head H is formed with a circular recess 8 for mounting the spark plug P and the pressure sensor S. A female screw 9 into which the screw portion 5 of the ignition plug P is screwed is formed at the center of the bottom wall of the recess 8, and an axial wire groove 10 is formed in the inner wall.

The wire groove 10 is formed by the lead wire S.
2 (a) to a size that allows the large diameter portion S2a of FIG.
Various shapes such as a circle, a triangle, a square, and a hexagon can be considered as shown in (d). In the wire groove 10, the width of the opening 11 at the communicating portion with the recess 8 is such that the large diameter portion S of the lead wire S2.
The narrower width than 2a, and the non-large diameter portion S2b of the lead wire S2
It is slightly wider. Therefore, the non-large-diameter portion S2b of the lead wire S2 enters the concave portion 8 through the opening 11, but the large-diameter portion S2a is fitted and restrained in the wire groove 10.

Next, the work of mounting the spark plug P and the pressure sensor S on the cylinder head H will be described.

First, in order to set the pressure sensor S in the recess 8 of the cylinder head H, the large diameter portion S2a of the lead wire S2 is inserted into the wire groove 10. In this case, the non-large-diameter portion S2b of the lead wire S2 is pulled out into the recess 8 through the opening 11. And the large diameter portion S2a
Put all in the recess 8 and the sensor body S of the pressure sensor S
1 is placed on the bottom wall of the recess 8. In this state, the lead wire S2 does not fall down because the large diameter portion S2a is fitted and restrained in the wire groove 10.

Next, the threaded portion 5 of the ignition plug P is inserted into the center hole S3 of the sensor body S1 and screwed into the female screw 9 of the recessed portion 8, and the ignition plug P is attached by the tightening socket 12 of the impact wrench as shown in FIG. Tighten and fix. Incidentally, when the ignition plug P is rotated during this tightening, a rotational force also acts on the pressure sensor S in some cases.
Since the large-diameter portion S2a of 2 is made of rubber, a cushioning function works,
The lead wire S2 is protected by this buffering action.

Although the embodiment has been described above, of course, the present invention is not limited to this. For example, regarding the relationship between the large diameter portion S2a of the lead wire S2 and the opening 11, as in the case of the embodiment, the dimensional difference between the outer diameter of the large diameter portion S2a and the width of the opening 11 is increased so as not to completely pass through. In addition, the dimensional difference between the outer diameter of the large diameter portion S2a and the width of the opening 11 is reduced,
Even if the large diameter portion S2a is deformed within the elastic limit and passes through the opening 11, it is sufficient to achieve the intended purpose. Also,
The large-diameter portion S2a is not limited to one as in the embodiment, but may be divided and provided at a plurality of locations. In that case, the large diameter portion S2a
It is preferable to provide one of them in the vicinity of the bent portion of the lead wire S2.

[0014]

As described above, according to the present invention, since the lead wire can be held in the wire groove, the lead wire may fall between the setting of the pressure sensor in the recess and the mounting of the spark plug. There is no effect, and the work of mounting the spark plug becomes extremely smooth, which has the effect of contributing to the improvement of workability.

[Brief description of drawings]

FIG. 1 is an overall exploded perspective view.

FIG. 2 is a partial cross-sectional plan view of a cylinder head showing a shape of a wire groove.

FIG. 3 is a partial vertical cross-sectional view of the cylinder head showing a state when the ignition plug is tightened.

[Explanation of symbols]

 S ... Engine pressure sensor S2 ... Lead wire S2a ... Large diameter portion S2b ... Non-large diameter portion P ... Spark plug 8 ... Recess 10 ... Wire groove 11 ... Opening

Continued front page (56) References Open 63-193337 (JP, U) Open 61-14342 (JP, U) Open 63-70049 (JP, U) Open 57-28350 (JP) , U)

Claims (1)

(57) [Scope of utility model registration request] 1. A position fixing structure for setting an engine pressure sensor in a recess for mounting an ignition plug, wherein a large diameter portion is formed in a part of a lead wire of the engine pressure sensor, A wire groove having a size such that the large diameter portion of the lead wire can fit on the inner wall, and the width of the opening of the communicating portion with the recess is narrower than the large diameter portion of the lead wire and slightly wider than the non-large diameter portion. The position fixing structure of the engine pressure sensor, wherein the large diameter portion of the lead wire is fitted and held in the wire groove in a state where the engine pressure sensor is set in the recess.