JPH05157652A - Assembly method of annular piezoelectric sensor - Google Patents

Abstract

PURPOSE:To enable an eccentric ring to be fitted into a metal coating in a method for assembling an annular piezoelectric sensor by inner-fitting an integration body by positioning an eccentric ring plate at an outermost part of a storage space of a metal coating where a rotation-stop peripheral edge which causes an outer-periphery edge to be subjected to eccentricity for an inner-periphery wall for overhang in radius direction at a periphery part of the outer-periphery wall and then assembling while caulking a folding margin of an edge of the inner and outer periphery walls of the metal coating. CONSTITUTION:An opening of a metal coating 7 is positioned on an upper part, an eccentricity ring is mounted in the opening of the metal coating, and a vibrator is allowed to contact the metal coating 7 or the eccentricity ring 6. The eccentric ring is moved in periphery direction, the eccentric ring 6 is dropped into the metal coating 7 according to self weight at a position where a shape of the eccentricity ring 6 matches that of the opening of the metal coating 7, thus achieving fitting uniformly into the metal coating 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembly of a piezoelectric sensor used in an in-cylinder pressure detection device for holding a cylinder head of an engine and detecting pressure fluctuations in the cylinder due to knocking or fuel injection by a piezoelectric element. Regarding the method.

[0002]

2. Description of the Related Art As a conventional in-cylinder pressure detecting device of this type, as shown in FIG. 7, an integrated body formed by stacking an annular piezoelectric element and upper and lower buffer rings and the like is wrapped with a metal outer cover. Various proposals have been made in which an annular piezoelectric sensor S is seated on a plug mounting portion R and a piezoelectric element in the piezoelectric sensor is distorted by clamping pressure of an ignition plug T to take out an output signal. More specifically, the plug mounting portion R includes a large-diameter plug insertion hole r ₁ , which is sequentially formed from the outer surface of the cylinder head P toward the combustion chamber Q, a plug seat r _2, and a small-diameter plug screw engagement. consists hole r ₃ Prefecture, the plug insertion hole r ₁ from the spark plug T is inserted, is screwed to the male screw t ₁ in screw hole r _3, the seat surface via a gasket ring optionally t ₂ The pressure of the piezoelectric sensor S on the plug seat r ₂ is strongly applied between the and so that the spark discharge part t ₃ thereof faces the combustion chamber Q.

The vibration of the cylinder head P causes a compressive strain in the piezoelectric element in the piezoelectric sensor S, and an output signal synchronized with the vibration is taken out from the piezoelectric element, which is used for detecting knocking and fuel injection timing. Be done.

[0004]

By the way, in the type in which the piezoelectric sensor S is clamped by tightening the ignition plug as described above, the piezoelectric sensor S has a direct tightening torque when the ignition plug T is attached, or a gasket. It acts through the ring, and in addition to compressive stress, torsional stress is superimposed and applied. Therefore, the characteristics are deteriorated and the piezoelectric element having a small shear strength is easily broken. Therefore, it is usually used together with a detent member having various structures, but the use of this detent member complicates the sensor structure, impairs productivity and economical efficiency, raises the price, and makes the piezoelectric sensor S unusable. Spark discharge part t ₃ of the spark plug T which is raised and protrudes into the combustion chamber
There is a problem such that it becomes difficult to set the position of the position to a predetermined position.

Therefore, the outer peripheral wall is eccentric with respect to the inner peripheral wall, and at least the annular piezoelectric element and the lowermost portion are arranged by a metallic outer skin having a peripheral edge of the outer peripheral wall formed with a rotation stopping peripheral edge. A piezoelectric sensor S having a structure including an integrated body including an eccentric ring plate is proposed. Due to the eccentric configuration, the piezoelectric sensor S has a detent peripheral edge that extends in the radial direction, and thus it is possible to prevent a torsional stress from being applied to the piezoelectric sensor S by the tightening torque without using the detent member as described above. It is a thing.

The piezoelectric sensor S is assembled between the outer peripheral wall and the inner peripheral wall of the metal outer skin which is formed in advance in the shape of a heavenly annulus whose bottom is opened by extending the folding margin between the both outer peripheral walls. The eccentric ring plate is located at the outermost position in the eccentric storage space, the stack is fitted in the storage space, the storage space is shielded by the eccentric ring plate, and the edge of the inner and outer peripheral walls of the metal outer cover is folded. The eccentric ring plate is caulked in close contact with the inner and outer edges.

In such an assembling means, the metal skin and the eccentric ring plate are eccentric in the same manner, and the eccentric ring plate is formed so as to be fitted tightly in the storage space of the metal skin. .. By the way, in each constitution of the aggregate other than the eccentric ring plate, since it is annular, it can be easily fitted by being fitted onto the inner peripheral wall without any trouble in any of the circumferential direction, but the eccentric ring plate is Since they are not annular, they cannot be stored unless they are piled up with the shapes perfectly matched. For this reason, the storage work becomes troublesome, and it has emerged as a major problem in mass production. An object of the present invention is to make it possible to easily attach the eccentric ring to the inside of the metal outer cover in the piezoelectric sensor having such a configuration.

[0008]

SUMMARY OF THE INVENTION According to the present invention, an opening of a metal outer cover is located at an upper portion, an eccentric ring is mounted on the opening of the metal outer cover, and the vibrating body excites the eccentric ring. By moving the eccentric ring in the circumferential direction, the eccentric ring plate is evenly fitted in the metal outer cover.

[0009]

The eccentric ring attached to the opening of the metal skin moves in the circumferential direction while being excited while being locked to the upper edge of the outer peripheral wall of the metal skin. When the opening and the eccentric ring are in a uniform position, the opening is dropped into the opening by its own weight, and the eccentric ring plate is fitted inside the metal outer skin, and the fitting is easily performed. Can be given. In this way, the piezoelectric sensor is assembled by accommodating the laminated body in the accommodating space of the metal skin and crimping the folding margin of the inner and outer peripheral walls.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a piezoelectric sensor S will be described with reference to FIG. 1. Reference numeral 1 is an integrated body, each of which is stacked through an annular piezoelectric element 2, an electrode ring 3, and an insulating plate 4 made of alumina or the like. A ring plate 5 made of a metal material such as copper, aluminum, and stainless is arranged on the upper surface thereof, and an eccentric ring plate 6 of the same material is arranged on the lower surface thereof, and the integrated body 1 is drawn with a metal skin 7 by drawing. It is wrapped and the joint 13 is located on the lower surface of the eccentric ring plate 6. The corner edges of the ring plate 5 and the eccentric ring plate 6 may be chamfered to improve the adhesion with the outer cover 7.

In the piezoelectric sensor S, the shape of the outer peripheral wall 7a of the metal outer skin 7 is made substantially the same as the outer periphery of the plug seat r ₂ formed in the plug mounting portion R of the cylinder head P, and the plug screwing hole r is formed. The center L of ₃ is deviated from the center D of the plug seat r ₂ so that the arc center of the inner peripheral wall 7b of the metal outer shell 7 is eccentric to the arc center of the outer peripheral wall 7a, and the center L of the plug screw hole r ₃ It is made to coincide with (the axial center of the spark plug T). As a result, the planar (bottom) shape of the piezoelectric sensor S becomes an annular shape whose radial widths are different over the entire circumference as shown in FIG. 5, and the rotation stopping peripheral edge α is formed on the deviation surface of the outer peripheral wall 7a. To be done. And the said integrated body 1 is arrange | positioned along the inner peripheral wall 7b. Here, the upper metal ring plate 5 has an annular shape in which the inner edge and the outer edge are concentric, similar to the piezoelectric element 2, but the eccentric ring plate 6 matches the eccentric shape of the metal outer skin 7, The centers of the inner edge and the outer edge are respectively deviated so that the eccentric ring plate 6 constitutes the bottom plate.

To explain the electrical take-out means of the piezoelectric sensor S, a connecting branch 3a is extended on the electrode ring plate 3, and the connecting branch 3a is displaced in the metallic outer skin 7 by the displacement of the arc center. The peripheral edge and the outer peripheral wall 7 of the aggregate 1 to be formed
The connection branch 3a is located in a gap s generated between the inner surfaces of a, and the connection branch 3a is drawn out from the extraction hole 8 formed in the metal outer skin 7 immediately above the gap s, and the connection branch 3a is inserted into the metal guide pipe 9. Then, the guide pipe 9 is fixed to the lead-out hole 8, the signal carrying lead wire 10 is connected to the connecting branch 3a by soldering 11, and the protective pipe 12 is externally fitted.
As a result, the output signal is taken out from the signal carrying lead wire 10.

With this structure, the annular piezoelectric sensor S
When a pressure is applied to the piezoelectric sensor S by the ignition plugs T on the upper and lower surfaces thereof, the pressure directly acts on the upper and lower surfaces of the metal outer skin 7, and the piezoelectric material passes through the ring plate 5 and the eccentric ring plate 6. Acts on element 2. Then, in the piezoelectric element 2,
A voltage proportional to the pressure fluctuation is generated, and the electrode ring plate 3
Is taken out as an output signal via the signal carrying lead wire 10.

In such a structure, the piezoelectric sensor S is pressed against the seat surface t ₂ when the ignition plug T is attached, and the tightening torque acts due to the shearing stress, and the torsional stress as well as the compressive stress is superimposed. However, the axial center of the ignition plug T (center L of the plug screw hole r ₃ ) and the center D of the plug seat r ₂ (center of the outer peripheral surface of the piezoelectric sensor S) are deviated, and therefore the piezoelectric sensor The rotation stopping peripheral edge α formed on the outer peripheral surface of S abuts against the inner peripheral wall of the plug insertion hole r ₁ and cannot rotate. Therefore, only the compressive stress is applied to the piezoelectric sensor S, and the destruction of the piezoelectric element 2 due to the shear stress is prevented without using the rotation stopping member.

The rotation stopping peripheral edge α formed on the outer peripheral surface of the piezoelectric sensor S has, for example, a polygonal peripheral surface shape of the outer peripheral wall 7a of the metal outer cover 7 and the inner peripheral wall of the plug insertion hole r _1. If the polygon conforms to, the rotation-stopping peripheral edge α is formed on the entire circumference. Further, a part of the peripheral wall 7a is projected outward, and the projecting end is a rotation stopping peripheral edge α, and when it is rotated a little, the projecting end is brought into contact with the inner peripheral wall of the plug insertion hole r ₁ and locked, and its rotation. May be blocked.

A method of assembling the piezoelectric sensor S having the following structure will be described. As shown in FIGS. 3 and 5, in the state before the assembly, the metal outer skin 7 has a fold x,
y is extended to vertically hang down the outer peripheral wall 7a and the inner peripheral wall 7b, and an eccentric storage space 7 is provided between both peripheral walls 7a and 7b.
It is formed in advance in an open-ended circular shape that causes the bottom surface of c to form. The folding margin x at the lower edge of the inner peripheral wall 7b is longer than the folding margin y at the lower edge of the outer peripheral wall 7a. Then, the integrated body 1 excluding the eccentric ring plate 6 is concentrically fitted along the inner peripheral wall 7b in the metal outer skin 7 having such a configuration.

On the other hand, in FIG. 3, reference numeral 20 is a vibrating body, in which a vibrator 23 is arranged on the lower surface of a base 21, and the inner hole of the metal outer skin 7 is evenly arranged on the base 21. A guide protrusion 24 that fits inside is provided. Then, the above-mentioned integrated body 1 excluding the eccentric ring plate 6 is stored in advance in the metal outer skin 7, and the metal outer skin 7
After the inner hole is inserted into the guide convex portion 24 with its opening facing upward and is externally fitted to the vibrating body 20, the eccentric ring plate 6 is externally fitted to the guide convex portion 24. It is applied on the opening of the outer skin 7.

In this state, the vibrator 23 is driven,
The metal skin 7 and the eccentric ring plate 6 are excited through the vibrating body. As long as the eccentric ring plate 6 does not coincide with the opening of the metal outer skin 7, it is locked by the outer peripheral wall 7a on the opening and is movable in the circumferential direction. Therefore, the eccentric ring plate 6 moves in the circumferential direction while being supported by the guide protrusions 24 by its excitation, and at the position where the shape of the opening and the eccentric ring 6 match, the eccentric ring plate 6 is placed inside the metal outer skin 7 by its own weight. It will fall.

FIG. 4 shows another structure of the vibrating body. The horn type vibrator 30 using a piezoelectric element is used as the vibrating body.
The oscillating end 31 is brought into contact with the peripheral surface of the metallic outer skin 7 to vibrate the eccentric ring 6 and move it in the circumferential direction.

As described above, the vibrating body according to the present invention is only required to be in contact with the metal outer cover 7 or the eccentric ring plate 6 to excite it.

Then, as shown in FIG. 5, the aggregate 1 is fitted into the storage space 7c of the metal outer skin 7 and the storage space 7c is shielded by the eccentric ring plate 6, as shown in FIG. The assembling of the piezoelectric sensor S is completed by folding and crimping the respective folding margins x and y of the metal outer cover 7 and positioning the joint 13 on the lower surface. As shown in FIG. 6, the piezoelectric sensor S has an eccentric shape with the line segment 1 as the long axis, and the rotation stopping peripheral edge α is formed on the eccentric surface of the outer peripheral wall 7a.

[0022]

As described above, in the method of assembling the annular piezoelectric sensor S of the present invention, the opening of the metal outer cover 7 is positioned at the upper portion, and the eccentric ring is mounted on the opening of the metal outer cover. ,
The eccentric ring 6 is moved in the circumferential direction by being excited by a vibrating body, and the eccentric ring plate 6 is dropped into the metal outer skin 7 by its own weight at a position where the shape of the eccentric ring 6 and the opening of the metal outer skin 7 match. Since the metal outer skin 7 and the eccentric ring plate 6 are fitted into the metal outer skin 7 in a uniform manner.
Despite each being eccentric, the fitting work can be easily performed with a simple configuration, and there is an excellent effect that the assembling process can be efficiently performed.

[Brief description of drawings]

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

2 is a partially cutaway plan view of FIG. 1. FIG.

FIG. 3 is a schematic side view showing a fitting means for fitting an eccentric ring plate 6 and a metal outer cover 7.

FIG. 4 is a schematic side view of a main part showing another fitting means.

FIG. 5 is a vertical cross-sectional side view of the metal outer cover 7 before caulking.

FIG. 6 is a bottom view of the pressure sensor after caulking.

FIG. 7 is a vertical sectional front view schematically showing an in-cylinder pressure detection device according to a conventional example.

[Explanation of symbols]

 S Piezoelectric sensor 1 Integrated body 2 Piezoelectric element 6 Eccentric ring plate 7 Metal outer skin 7a Outer peripheral wall 7b Inner peripheral wall 7c Storage space 20 Vibrating body 30 Vibrator α rotation peripheral edge

Claims (1)

[Claims] 1. An outer peripheral wall is eccentrically arranged with respect to an inner peripheral wall to form a detent circumferential edge that extends radially in a peripheral portion of the outer peripheral wall, and a folding allowance is extended to end portions of the outer peripheral wall and the inner peripheral wall. A metal shell that is preformed in a heavenly annular shape with an open bottom surface, and the eccentric ring plate is positioned at the outermost position in the eccentric storage space that is formed between the peripheral walls of the metal shell, and the aggregate is fitted inside the metal shell. In an assembling method in which the edges of the inner and outer peripheral walls of the outer skin are crimped to assemble, the opening of the metal outer cover is located at the upper part, and an eccentric ring is mounted on the opening of the metal outer cover. At the same time, the eccentric ring plate is uniformly fitted in the metal outer skin by exciting the eccentric ring in the circumferential direction by vibrating the vibrating body. Assembling method.