JPH06281524A - Cylinder inside pressure detector and method for regulating its height - Google Patents

Abstract

PURPOSE:To provide a cylinder inside pressure detector and a method for regulating its height capable of mechanically and electrically protecting a connection part, whose outer circumferential shape is simple, coupled to a lead wire, easily manufactured in response to depth of a plug-inserted hole without needing special work in the plug-inserted hole and equipping wide utility for said depth. CONSTITUTION:Constitution is performed in that an inside makes an insertion void 5 of an ignition plug T, an integration body 14 for equipping a piezoelectric element 17 is housed in an inner flange part 6 and a lead wire 20 connected to an electrode of the piezoelectric element 17 is electrically drawn out. At this time other constitution is performed in that an inside cylindrical metal fitting 3 and an outside cylindrical metal fitting 4 are concentrically connected to a base division cylinder and one or more side division cylinders. In addition, a flange edge 7 outwardly projected on an upper edge of a cylindrical housing body 2 is formed in response to depth of a plug insertion hole r1 rubber 11 is outside fitted on the upper part of said housing body 6 and height adjustment of the rubber 11 can respond to the depth of the plug insertion hole r1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder pressure detection device for holding a cylinder head of an engine and detecting a pressure fluctuation in the cylinder due to knocking or combustion by a piezoelectric element, and a height adjusting method thereof.

[0002]

2. Description of the Related Art As a conventional in-cylinder pressure detecting device of this type, as shown in FIG. 13, an annular piezoelectric sensor S constituted by wrapping an integrated body including an annular piezoelectric element in a metal shell is provided with a plug mounting hole R. Various devices have been proposed in which the piezoelectric element in the piezoelectric sensor S is strained by the clamping pressure of the ignition plug T and the output signal is taken out from the lead wire L connected to the piezoelectric element. More specifically, the plug mounting hole R has a large diameter plug insertion hole r formed in order from the outer surface of the cylinder head P toward the combustion chamber Q.
₁ , a plug seat r ₂ and a small-diameter plug screwing hole r ₃ into which the ignition plug T is inserted through the plug inserting hole r ₁ and its male screw t ₁ is screwed into the screwing hole r _3. Then, if necessary, the piezoelectric sensor S on the plug seat r ₂ is strongly pressed between itself and the seat surface t ₂ via the gasket ring so that the spark discharge part t ₃ faces the combustion chamber Q. .

When the plug receives the pressure fluctuation in the cylinder head P and the clamping load of the plug changes, the strain of the piezoelectric element in the piezoelectric sensor S changes, and a signal synchronized with the change is applied to the piezoelectric element. It is used to detect knocking and combustion pressure.

[0004]

In the above structure, the lead wire L is not held in the plug insertion hole r ₁ , the mountability is poor, and the wiring process is troublesome.
Is damaged at the corner edge of the spark plug T, and is easily broken during mounting. Therefore, in order to isolate the electrical take-out means from the ignition plug T and the piezoelectric element, Japanese Patent Application Laid-Open No. 61-61606
-12535, using a metal cylinder,
A configuration has been proposed in which a piezoelectric sensor is fixed to the lower end of the metal cylinder and the lead wire is pulled out from a gap formed between the outside of the metal cylinder and the plug insertion hole.

By the way, in such a structure, a means such as connecting the core wire of the lead wire connected to the external device side and the lead wire connected to the piezoelectric element and then covering this with a protective tube is taken. However, since it is an external connection, mechanical protection is not sufficient and breakage easily occurs during installation. In addition, the outer peripheral shape is complicated and the mountability is poor. Moreover,
In order to allow the lead wire to be drawn out, it is necessary to process and form a guide groove for the lead wire in the plug insertion hole, and the cross-sectional shape of the plug insertion hole is specialized, which makes the formation troublesome, and it is a general-purpose sensor There was a problem such as loss of sex.

The present invention eliminates such problems and can be easily manufactured in accordance with the depth of the plug mounting hole R,
Further, it is an object of the present invention to provide a cylinder internal pressure detection device having versatility with respect to the depth and a height adjusting method thereof.

[0007]

SUMMARY OF THE INVENTION According to the present invention, an inner hole is used as an opening for inserting a spark plug, and a lower end is formed into a double cylindrical shape having an inner collar portion for locking the spark plug. Of the cylindrical container formed by creating a peripheral gap with the outer cylinder wall,
A ring-shaped integrated body having a ring-shaped piezoelectric element is held in its inner flange portion, and a lead wire connected to an electrode of the piezoelectric element is electrically drawn upward from the peripheral gap. Is a cylinder internal pressure detecting device which is housed in a portion and is mounted with the inner flange portion being clamped and held between a plug seat and an ignition plug.

In this structure, the inner cylindrical metal fitting and the outer cylindrical metal fitting having a diameter larger than that of the cylindrical metal fitting are concentrically fitted to each other and fixed at the lower edge so that the ignition plug is locked. Constructing the cylindrical housing having a collar portion, and concentrically joining an inner cylindrical metal fitting, an outer cylindrical metal fitting, a base division cylinder holding an annular integrated body, and one or more side division cylinders. It can be configured by.

Further, a brim projecting outward is formed at the upper edge of the cylindrical container, and a rubber is externally fitted on the upper part of the container so that the upper edge abuts against the brim and the lower edge is It makes elastic contact with the upper surface of the cylinder head P, thereby maintaining watertightness between the peripheral surface of the outer cylinder wall and the inner surface of the plug insertion hole r ₁ , and adjusting the height of the rubber to make the depth of the plug mounting portion of the cylinder head P _1. It is possible to use a height adjusting method adapted to the above.

[0010]

The integrated body including the piezoelectric element and the wiring member such as the lead wire connected to the electrode of the piezoelectric element are mounted in the cylindrical housing. Therefore, the lead wire and the like are not attached externally, the device can have a uniform cross-sectional shape, the cylinder head is easily attached to the plug mounting portion, and the lead wire insertion hole is formed in the plug mounting portion. There is no need to do it.

Further, deep drawing is required by concentrically joining the inner cylindrical metal member, the outer cylindrical metal member, and the base divided cylinder having the inner flange portion and one or more side divided cylinders. Therefore, the processing becomes easy, and by changing the height of the side split cylinder, it is possible to easily manufacture the cylindrical metal fittings having various heights.

Further, by using the height adjusting method described above, even if the depth of the plug mounting portion of the cylinder head changes, the cylinder internal pressure detecting device having the same size can be applied.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a cylinder internal pressure detecting device 1 according to the present invention will be described with reference to FIGS.

Reference numeral 2 denotes a cylindrical container, which is constructed by assembling an inner cylindrical metal member 3 and an outer cylindrical metal member 4 into a double cylindrical shape. The inner hole serves as an insertion gap 5 for the spark plug p, and the inner flange portion 6 for locking the spark plug p is provided at the lower end, and the upper end is opened between the inner cylindrical wall 8 and the outer cylindrical wall 9. A peripheral gap 10 communicating with the inside of the collar portion 6 is formed.

The structure of the cylindrical housing 2 will be described in more detail. The inner cylindrical metal member 3 and the outer cylindrical metal member 4 are superposed and joined to each other at their lower bottoms, and the superposing portion seals the pinching action of the ignition plug. I try to act in the direction. Moreover, the diameter of the upper part of the outer cylindrical metal fitting 4 is made large, and the width of the peripheral gap 10 generated between the outer cylindrical metal fitting 3 and the inner cylindrical metal fitting 3 is increased, so that the lead wire 20 described later can be inserted. Moreover,
The upper end of the inner cylindrical metal member 3 is bent outward on the outer cylindrical metal member 4 to form a brim 7, and the upper end of the rubber 11 fitted on the outer cylindrical metal member 4 is joined to the brim 7. An extraction hole 13 that communicates with the peripheral gap 10 may be formed in a part of the brim 7.

The lower surface of the rubber 11 has a crushed ridge 11a.
Are formed. Then, in the attached state, the rubber 11 elastically contacts the upper surface of the cylinder head P, thereby maintaining the watertightness between the peripheral surface of the outer cylinder wall 9 and the inner surface of the plug insertion hole r ₁ . Furthermore, when the ignition plug T is attached, the internal torque is pressed against the inner flange portion 6 and the tightening torque acts on the cylinder internal pressure detection device 1 due to the shear stress, but the rubber 11 is pressed against the wall surface of the cylinder head P to generate a contact resistance. The rotation will be blocked.

FIG. 4 shows another example of this sealing means. With this configuration, the rubber 30 fitted onto the outer cylindrical metal fitting 4
Has a plurality of crushed ridges 30a vertically formed on its peripheral surface. The upper end of the rubber 30 is joined to the flange 7, and the edge of the flange 7 is projected further outward than the upper surface of the rubber 30. In such a configuration,
Rubber 30 is press-fitted into the plug insertion hole r ₁ of the cylinder head P, crushing Takashi portion 30 on the upper inner surface of the plug insertion hole r ₁
Since a is pressed, the watertightness of the inner surface of the plug insertion hole r ₁ and the rotation preventing effect of the cylinder internal pressure detection device 1 are produced. Further, the edge of the brim 7 covers the inner surface of the plug insertion hole r ₁ to complement the watertightness.

In the cylindrical container 2 having such a structure, the ring-shaped integrated body 14 is housed in the inner flange portion 6. The ring-shaped integrated body 14 is formed by stacking an insulating plate 15 made of alumina or the like in a ring shape, an electrode plate 16 made of a metal material such as copper, aluminum or stainless steel, a piezoelectric element 17 and a metal plate packing 18 on top of each other. An insulating tube 19 is arranged on the peripheral surface to insulate the inner cylindrical metal fitting 3, and the annular aggregate 14 is wrapped in the inner cylindrical metal fitting 3 and the outer cylindrical metal fitting 4 by drawing as will be described later and held tightly. ,
As described above, the joint is located on the lower surface.

The electrical take-out means of the cylinder internal pressure detecting device 1 will be further described. A connecting branch 16a is formed on the electrode plate 16, and the connecting branch 16a is positioned at a right angle to the surrounding gap 10 side. ing. Then, the core wire 21 of the lead wire 20 is connected to the connecting branch 16a in the wide circumferential gap 10.
Electrically connected to. The connecting branch 16a is covered with an insulating tube 22 made of, for example, polyimide or fluororesin in the peripheral gap 10 to prevent a short circuit between the inner cylindrical metal fitting 3 and the outer cylindrical metal fitting 4. Further, the connecting portion between the core wire 21 of the lead wire 20 and the connecting branch 16a is further covered with the insulating tube 23.

The lead wire 20 is drawn out from the drawing hole 13 and a connector 24 is connected to its end.
A filler 25 is placed in the peripheral gap 10 and the annular gap.
Is filled, so that the electrical connection portion is stably held and watertightness is generated to prevent an electrical short circuit due to moisture. In addition, a pipe 26 that holds the lead wire 20 is joined to the lead-out hole 13 of the lead wire 20.

Next, the assembling means of the cylinder internal pressure detecting device 1 having the above construction will be described with reference to FIG. The lower end of the inner cylindrical metal member 3 is a vertical cylinder end 3a before assembly. Then, each member such as the piezoelectric element 17 constituting the annular integrated body 14 is fitted on the receiving flange portion 4a of the outer cylindrical metal fitting 4 in a predetermined order. At this time, the lead wire 20 is connected to the connecting branch 16a in advance and covered with the insulating tubes 22 and 23 to secure the electrical connection. The insulating tube 19 is also fitted to the base end of the vertical tube end 3a. And after that, the inner cylindrical metal fitting 3
The vertical cylindrical end 3a of the above is inserted into the receiving flange portion 4a of the outer cylindrical metal fitting 4, and the lead wire 20 is inserted through the extraction hole 13 through the pipe 26. Then, the vertical cylinder end 3a is folded outward by bending, overlapped with the lower surface of the receiving flange 4a, and the overlapped end is connected by, for example, laser welding. Further, the filler 25 is filled into the peripheral gap 10 through the opening at the lower portion of the collar edge 7, the rubber 11 is externally fitted to the outer cylindrical metal member 4, the pipe 26 is caulked, and the lead wire 20
The connector 24 is connected to the end of the. As a result, the cylinder pressure detection device 1 is completed.

Then, the cylinder internal pressure detecting device 1 is inserted into the plug insertion hole r ₁ of the cylinder head P. In this case, since the outer circumference of the cylinder internal pressure detection device 1 has a uniform circular cross section and the wiring members such as lead wires are not exposed, the mounting can be easily performed. And
The spark plug T is screwed into the plug screwing hole r ₃ of the cylinder head P, the inner flange portion 6 is clamped to apply a preload, and the mounting is completed.

Thus, the clamping load of the plug T changes due to knocking or changes in combustion pressure, so that the piezoelectric element 1
The strain of No. 7 fluctuates, and an output signal synchronized with the change is generated and taken out from the lead wire 20 to the external device side via the connector 24. In the configuration of the cylindrical container 2 described above,
The inner cylindrical metal member 3 and the outer cylindrical metal member 4 are integrally formed of a single member at their lower ends by means such as welding and brazing. By the way, in recent years, four valves have become the mainstream of the engine, and the plug can now be mounted in the center of the combustion chamber, so the depth of the plug mounting hole R of the cylinder head P is increasing. Therefore, when the inner cylindrical metal fitting 3 and the outer cylindrical metal fitting 4 having a single structure are used as described above, the cylindrical metal fittings 3 and 4 are formed by drawing, but the drawing length (depth) is It is difficult to deal with this because there is a limit.

Therefore, as shown in FIG.
Base divided cylinders 3a, 4a for holding 4 and side divided cylinder 3
The cylindrical metal fittings 3 and 4 can be constructed by concentrically joining with b and 4b. In this case,
The upper ends m ₁ and n ₁ of the base divided cylinders 3a and 4a are expanded outward by connecting at the expanded diameter part x, and the side divided cylinders 3b and 4b are connected.
Each of the lower ends m ₂ and n ₂ can be simplified by reducing the diameter inward at the same inclination angle.

In this structure, the base divided cylinders 3a, 4
a is formed by drawing, and the side divided tubes 3b and 4b are formed by bending the pipe. For this reason, in the configuration of FIG. 1, the inner cylindrical metal fitting 3 and the outer cylindrical metal fitting 4 are formed by deep drawing. If the depth exceeds 100 mm, it is difficult to form by deep drawing. However, as described above, the side divisional cylinders 3b and 4 are divided into two and the length thereof is determined.
Since b is performed by bending the pipe, the molding becomes easy. Moreover, plug mounting holes R of various depths
Corresponding to, if the length of the side divided cylinders 3b, 4b is changed,
The same products can be used for the base divided cylinders 3a and 4a,
The length can be accommodated without requiring a new mold.

Next, a method of forming the above-mentioned base divided cylinders 3a and 4a by drawing and forming the side divided cylinders 3b and 4b will be described with reference to FIGS.

As shown in FIG. 6, the base divided cylinder 3a is formed by drawing a disk (a) into a shape of (b) by drawing in one to several steps, and then a hole is formed in the bottom and the upper end is cut off to the outside. The shape of (c) is provided with the connection edge m ₁ inclined to. The portion vertically protruding from this bottom portion is the annular assembly 14 when assembled.
After the outer cylindrical metal fitting 4 and the outer cylindrical metal fitting 4 are externally fitted, bending work is performed outward as indicated by an arrow to form the inner flange portion 6.

As shown in FIG. 7, the side divided cylinder 3b is formed into a (b) shape by bending the end of the pipe (a) to form a brim 7, and is further drawn out to the brim 7. Hole 1
After drilling 3, the tip is bent inward and the connection edge m
The shape of (C) with ₂ is used.

As shown in FIG. 8, the base division cylinder 4a is formed by drawing a disk (a) into a shape (b), and further, a hole is formed in the bottom, and the upper end is cut off so that the connecting edge is inclined outward. n
Shape (c) with ₁ .

The side split cylinder 4b is subjected to a drawing process to the pipe (A) as shown in Figure 9 to the shape of (b), with a connection edge n ₂ further bend the distal end portion inwardly processed and ( C)

Then, the base divided cylinder 3a and the side divided cylinder 3
The inner cylindrical metal fitting 3 is formed by welding b to the connecting edges m ₁ and m ₂ . Further, the outer cylindrical metal fitting 4 is formed by welding the base divided cylinder 4a and the side divided cylinder 4b at the connection edges n ₁ and n ₂ .

In such a structure, the side divided cylinders 3b, 4
A plurality of b may be used.

The connecting position may be the position of the expanded diameter portion y in FIG. In addition, the joining means does not form an inclined connection edge, but is formed by overlapping and joining at a vertical portion as shown in FIG. 10A, or by abutting end edges as shown in FIG. May be.

As a means for adjusting the depth of the plug insertion hole r _1, a corresponding adjusting method is proposed by adjusting the height of the rubber 11 which is fitted on the outer cylindrical metal member 4 and abuts on the flange 7. obtain.

That is, as shown in FIG. 11, when the plug insertion hole r ₁ is shallower than that in FIG. 1, the rubber 11 having a large height is applied to maintain the watertightness and the same size. The cylinder internal pressure detection device can be applied. Therefore, if the elongated cylindrical metal fittings 3 and 4 corresponding to the maximum depth are formed by applying the above-mentioned two-division forming means, the same metal fittings 3 and 4 can cope with various depths. .

On the other hand, the rubber 11 may be composed of a base rubber 12a and an adjusting rubber 12b composed of a rubber ring spacer as shown in FIG. With this configuration, the depth of the plug insertion hole r ₁ can be handled by changing the thickness of the adjusting rubber 12b or the number of the adjusting rubbers 12b to be mounted, with the base rubber 12a being common.

[0037]

As described above, the cylinder internal pressure detecting device 1 of the present invention has the interior as the insertion gap 5 of the spark plug T,
The integrated body 14 including the piezoelectric element 17 is housed in the inner flange portion 6, and the lead wire 20 for connecting to the electrode of the piezoelectric element 17 is electrically connected from the peripheral gap 10 between the inner cylindrical wall 8 and the outer cylindrical wall 9. Since it is constructed by being pulled out, the electrical connection portion is protected inside the cylindrical housing body 2 and the connection is stably secured. Further, since the lead wire 20 and the like are not attached externally, the device can have a uniform cross-sectional shape, the cylinder head P can be easily mounted in the plug insertion hole r ₁ , and the plug insertion hole r
_Since there is no need to form a guide groove for drawing out the lead wire 20 in ₁ , there is versatility. Further, the insulation from the cylinder head P is secured, the electrical connection means is simplified, and the assembly is easy.

Also, in such a structure, the inner cylindrical metal fitting 3
And the outer cylindrical metal member 4 are configured by concentrically joining the base divided cylinders 3a, 4a and one or more side divided cylinders 3b, 4b, the deep drawing becomes unnecessary. Processing becomes easy, and by changing the heights of the side divided cylinders 3b and 4b, it is possible to easily form various heights.

Further, a flange 7 projecting outward is formed on the upper edge of the cylindrical container 2, and the rubber 1 is provided on the upper part of the container 2.
1 is externally fitted and the height of the rubber 11 is adjusted so as to correspond to the depth of the plug insertion hole r ₁ of the cylinder head, thereby changing the depth of the plug insertion hole r _1. However, it is possible to apply the cylinder internal pressure detection device having the same size, and there is an excellent effect that the versatility is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an in-cylinder pressure detection device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a lower portion.

FIG. 3 is an exploded perspective view.

FIG. 4 is a partial vertical cross-sectional side view showing another example of the sealing means.

FIG. 5 shows base divided cylinders 3a and 4a and side divided cylinders 3b and 4
It is an expanded sectional view of the lower part which shows the connection of b.

FIG. 6 is an explanatory view showing a forming process of the base divided cylinder 3a.

FIG. 7 is an explanatory view showing a forming process of the side divided tube 3b.

FIG. 8 is an explanatory view showing a forming process of the base divided cylinder 4a.

FIG. 9 is an explanatory diagram showing a forming process of the side divided tube 4b.

FIG. 10 shows base divided cylinders 3a, 4a and side divided cylinders 3b,
It is sectional drawing which shows the other connection means of 4b.

11 is a vertical sectional front view showing an application example of a rubber 11. FIG.

FIG. 12 is a perspective view of a rubber 11 including a base rubber 12a and an adjusting rubber 12b.

FIG. 13 is a vertical cross-sectional front view schematically showing a cylinder pressure detection device according to a conventional example.

[Explanation of symbols]

 1 Cylinder Pressure Detection Device 2 Cylindrical Housing 3 Inner Metal Fitting 3a Base Divided Cylinder 3b Side Divided Cylinder 4 Outer Metal Fitting 4a Base Divided Cylinder 4b Side Divided Cylinder 5 Insertion Gap 6 Inner Collar 8 Inner Cylinder Wall 9 Outer Cylinder Wall 10 Surrounding Gap 11 Rubber 12a Base Rubber 12b Adjusting Rubber 14 Annular Integrated Body 17 Piezoelectric Element 20 Lead Wire 30 Rubber

Claims (4)

[Claims] 1. A double-cylinder shape having an inner hole as an opening for inserting a spark plug and having an inner flange portion for locking the spark plug at a lower end thereof, and surrounding the inner cylinder wall and the outer cylinder wall. A cylindrical accommodating body having a gap formed therein holds an annular integrated body having an annular piezoelectric element in its inner flange portion, and electrically connects a lead wire connected to an electrode of the piezoelectric element upward from the peripheral gap. A cylinder internal pressure detection device which is constructed by being drawn out, is housed in a plug mounting portion of a cylinder head, and is mounted by holding the inner flange portion between a plug seat and an ignition plug with a clamping pressure. 2. The inner cylindrical metal fitting and the outer cylindrical metal fitting having a diameter larger than that of the cylindrical metal fitting are concentrically fitted to each other and fixed at a lower edge thereof to have an inner flange portion for locking an ignition plug. In addition to constituting the cylindrical housing, the inner cylindrical metal fitting, the outer cylindrical metal fitting is configured by concentrically joining the base division cylinder holding the annular aggregate and one or more side division cylinders. The cylinder internal pressure detection device according to claim 1. 3. A collar edge projecting outward is formed on an upper edge of the cylindrical container, a rubber is externally fitted on an upper portion of the container and the upper edge is brought into contact with the flange edge, and the lower edge is a cylinder. It makes elastic contact with the upper surface of the head, thereby maintaining watertightness between the peripheral surface of the outer cylinder wall and the inner surface of the plug insertion hole, and adjusting the height of the rubber to correspond to the depth of the plug mounting part of the cylinder head. The height adjusting method in the cylinder internal pressure detecting device according to claim 1, wherein 4. The rubber is composed of a base rubber and an adjusting rubber, and the thickness or the number of the adjusting rubbers is changed to correspond to the depth of the plug mounting portion of the cylinder head. The height adjusting method in the cylinder pressure detecting device according to claim 3.