JP2017223475A - Non-resonance type knocking sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-resonance type knocking sensor that has excellent insulation quality and realizes reduction in the number of components.SOLUTION: A non-resonance type knocking senor 1 has: a main fitting 11 that includes a fitting-side cylindrical part 11A and a fitting-side flange part 11B; a piezoelectric element 14; a weight 17; a flange-side electrode plate 13; a weight-side electrode plate 15; and an insulating member 21. The insulating member integrally has: an insulating cylinder part 20c; a flange-side insulating part 20a that radially extends outward from an outside surface of the insulating cylinder part; and a weight-side insulating part 20b that radially extends outward from the outside surface of the insulating cylinder part while separating from the flange-side insulating part. The insulating cylinder part is arranged among the fitting-side cylindrical part, the flange-side electrode plate, the piezoelectric element and the weight-side electrode plate, and thereby electrically insulates among them. The flange-side insulating part is arranged between the fitting-side flange part and the flange-side electrode plate, and thereby electrically insulates between them. The weight-side insulating part is arranged between the weight and the weight-side electrode plate, and thereby electrically insulates between them.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a knocking sensor using a piezoelectric element.

  An internal combustion engine such as an automobile is provided with a knocking sensor for detecting a knocking phenomenon, and control for suppressing the occurrence of the knocking phenomenon is performed in accordance with a detection signal output from the knocking sensor. Specifically, retardation control is performed to change the ignition timing of the ignition plug in the internal combustion engine in accordance with the output signal of the knocking sensor.

As the above-described knocking sensor, a so-called center-hole type non-resonant knocking sensor having a mounting hole for mounting to a cylinder block or the like of an internal combustion engine at the center is known (Patent Document 1). This knocking sensor includes a metal shell having a metal fitting-side cylindrical portion and a metal fitting-side flange portion located at one end thereof, and the outer circumference of the metal fitting-side cylindrical portion in turn from the metal fitting side flange portion side, respectively, The insulating plate, the flange side electrode plate, the piezoelectric element, the weight side electrode plate, the weight side insulating plate, and the weight are inserted. Then, the weight is locked by screwing the weight to the external thread portion of the outer peripheral surface of the metal fitting-side cylindrical portion, and the piezoelectric element is sandwiched and fixed between the metal fitting side collar portion and the weight. Furthermore, the knocking sensor is configured by covering the entire internal component (sensor body) in which the piezoelectric element, the weight, and the like are assembled to the metal shell with resin. In addition, the inner surface of the metal part side cylindrical part is the above-described mounting hole.
A cylindrical insulating sleeve is fitted between the outer peripheral surface of the bracket-side cylindrical portion and the flange-side electrode plate, the piezoelectric element, and the weight-side electrode plate to electrically insulate them. Yes. That is, the insulation is made by the three-piece members in which the annular flange side insulating plate and the weight side insulating plate are respectively arranged at both ends of the cylindrical insulating sleeve.

JP2012-237717A (FIG. 7)

However, there may be a gap between the insulation sleeve and the flange side insulation plate or the weight side insulation plate. Metal powder generated when the weight is screwed into the gap enters the gap between the piezoelectric element and the metal shell. There is a risk of lowering the insulation between them. Further, when the insulating member is composed of a plurality of parts (three pieces) as described above, the cost increases due to the increase in the number of parts and the productivity is lowered.
That is, an object of the present invention is to provide a non-resonant knock sensor having excellent insulation and a reduced number of components.

  The non-resonant type knocking sensor of the present invention includes a metal fitting side cylindrical portion formed in a cylindrical shape, and a metal fitting side collar portion extending radially outward from one end of the metal fitting side cylindrical portion. The metal fitting, the piezoelectric element with the metal fitting side cylindrical portion inserted through the through hole, and the metal fitting side cylindrical portion is inserted into the through hole, and the piezoelectric element is sandwiched between the metal fitting side flange. A weight side electrode plate disposed between the piezoelectric element and the metal fitting side collar, a weight side electrode plate disposed between the piezoelectric element and the weight, and an insulating member. A non-resonant type knocking sensor comprising a sensor main body and a resin molded body made of resin that covers the sensor main body, wherein the insulating member has a cylindrical shape in which the metal fitting-side cylindrical portion is inserted into a through hole. Insulating tube portion and radially outward from the outer surface of the insulating tube portion A part-side insulating part, and a weight-side insulating part that extends radially outward from the outer surface of the insulating cylinder part while being separated from the flange-side insulating part in the axial direction of the insulating cylinder part. The cylindrical portion is disposed between the metal fitting-side cylindrical portion and the flange-side electrode plate, the piezoelectric element, and the weight-side electrode plate, and electrically insulates between them, and the flange-side insulating portion The portion is disposed between the metal fitting side collar and the collar side electrode plate, and electrically insulates between the metal fitting side collar and the collar side electrode plate, and the weight side insulation portion includes the weight and the weight. It is disposed between the side electrode plates, and electrically insulates between the weight and the weight side electrode plate.

  According to this non-resonant type knocking sensor, the insulating member is composed of one (one-piece) part integrally including an insulating cylinder portion, a flange side insulating portion, and a weight side insulating portion. For this reason, the insulating member can insulate the gap between the flange side electrode plate, the piezoelectric element and the weight side electrode plate to be insulated, and the metal shell without gaps (without breaks), and when the weight is screwed It can be suppressed that the metal powder generated in, for example, enters between the piezoelectric element and the metal shell through the gap and lowers the insulation. In addition, since the insulating member is composed of one (one-piece) part, the number of parts can be reduced, and the cost can be reduced and the productivity can be improved.

The insulating member may be made of rubber or resin.
According to this non-resonant type knocking sensor, since the insulating member is rubber that is an elastic body or resin that is thermally deformed, it is possible to easily assemble the buttocks side electrode plate, piezoelectric element, and weight side electrode plate to the insulating member. it can.

  According to the present invention, it is possible to obtain a non-resonant type knocking sensor that is excellent in insulation and has a reduced number of parts.

It is sectional drawing which follows the axial direction explaining the structure of the non-resonance type knocking sensor which concerns on one Embodiment of this invention. It is an exploded view explaining the structure of the sensor main body of FIG. It is sectional drawing which follows the axial direction of an insulating member. It is process drawing which shows an example of the method of attaching a collar part side electrode plate, a piezoelectric element, and a weight side electrode plate to an insulating member. It is process drawing which shows another example of the method of assembling a collar part side electrode plate, a piezoelectric element, and a weight side electrode plate to an insulating member.

Hereinafter, a non-resonant knock sensor according to an embodiment of the present invention will be described with reference to FIGS.
1 is a cross-sectional view of the non-resonant knock sensor 1 cut in the axial direction, FIG. 2 is an exploded perspective view of the sensor body 10 of the non-resonant knock sensor, and FIG. 3 is a cross-section of the insulating member 20 cut in the axial direction. It is shown.

The non-resonant type knocking sensor 1 of the present embodiment detects knocking in the internal combustion engine, and has a mounting hole 11D for mounting to the cylinder block of the internal combustion engine at the center as shown in FIG. This is a center hole type non-resonant type knocking sensor.
The non-resonant type knocking sensor 1 is configured by covering a sensor body 10 described later in detail with a resin molded body 30, and is formed into a short cylindrical shape as a whole. Further, a connector portion 31 is formed to protrude radially outward from a part of the outer peripheral surface of the non-resonant knock sensor 1 formed in a cylindrical shape. A first terminal 13A and a second terminal 15A extending from the lower electrode plate 13 and the upper electrode plate 15 are disposed inside the connector portion 31 (only the first terminal 13A is shown in FIG. 1). ). The connector part 31 is connected to an external connector (not shown).

  As shown in FIG. 2, the non-resonant type knocking sensor 1 includes a metal fitting-side cylindrical portion 11A formed in a cylindrical shape and an annular metal fitting-side flange portion 11B formed at the lower end of the metal fitting-side cylindrical portion 11A. The metal metal shell 11, the lower electrode plate (saddle side electrode plate) 13, the piezoelectric element 14, the upper electrode plate (weight side electrode plate) 15, and the weight 17, each formed in an annular shape, will be described in detail later. The insulating member 20 and the disc spring 18 are mainly included. The lower electrode plate 13, the piezoelectric element 14, the upper electrode plate 15, the weight 17, and the disc spring 18 are each formed with a through-hole through which the fitting-side cylindrical portion 11 </ b> A is inserted. A lower electrode plate 13, a piezoelectric element 14, an upper electrode plate 15, a weight 17, and a disc spring 18 are stacked on the outer periphery of the metal fitting side cylindrical portion 11A in this order from the metal fitting side flange portion 11B side.

As shown in FIG. 3, the insulating member 20 includes a cylindrical insulating cylinder portion 20 c having a through-hole 20 h and a disk-shaped flange portion extending radially outward from the outer surface of the tip end in the axial direction L of the insulating cylinder portion 20 c. The side insulating portion 20a and the disc-like weight side insulating portion 20b extending radially outward from the outer surface of the rear end in the axial direction L of the insulating cylinder portion 20c are integrally provided. That is, when the cross section in the axial direction L is viewed, the insulating member 20 has a flange-shaped (U-shaped) side shape with the flange-side insulating portion 20a and the weight-side insulating portion 20b spaced apart in the axial direction L. There is no.
As shown in FIG. 1, the metal fitting side cylindrical portion 11A is inserted into the through hole 20h, and the insulating cylinder portion 20c includes the metal fitting side cylindrical portion 11A, the lower electrode plate 13, the piezoelectric element 14, and the upper electrode plate 15. And is electrically insulated between them. The flange side insulating portion 20a is disposed between the metal fitting side flange portion 11B and the lower electrode plate 13, and electrically insulates between them. Similarly, the weight side insulating portion 20b is disposed between the weight 17 and the upper electrode plate 14, and electrically insulates between them.

A male screw portion 11C is formed on the outer peripheral surface of the metal fitting-side cylindrical portion 11A of the metal shell 11. On the other hand, on the inner surface of the nut 19, a female screw portion 19 </ b> A that engages with the male screw portion 11 </ b> C is formed. Then, when the female screw portion 19A of the nut 19 is screwed into the male screw portion 11C of the metal fitting side cylindrical portion 11A and the nut 19 is rotated, the nut 19 moves toward the metal fitting side collar portion 11B. The lower insulating plate 12, the lower electrode plate 13, the piezoelectric element 14, the upper electrode plate 15, the upper insulating plate 16, the weight 17, the insulating member 20, and the disc spring 18 are attached to the metal-side flange 11 </ b> B of the metal shell 11 by a nut 19. It is pressed toward and fixed.
The sensor body 10 includes the lower insulating plate 12, the lower electrode plate 13, the piezoelectric element 14, the upper electrode plate 15, the upper insulating plate 16, the weight 17, the disc spring 18, and the insulating member 20 fixed to the metal shell 11 in this way. And a nut 19.

In this embodiment, the insulating member 20 is made of rubber such as fluoro rubber having heat resistance of 150 ° C. or higher, but may be made of resin such as PET (polyethylene terephthalate) as described later.
Moreover, the resin molding 30 is comprised from the synthetic resin (for example, nylon 66, PPS) which is a resin mold material excellent in a moldability. The resin molded body 30 can be formed by injection molding.

  As described above, the insulating member 20 is composed of one (one-piece) part integrally including the insulating cylinder portion 20c, the flange side insulating portion 20a, and the weight side insulating portion 20b. For this reason, the insulating member 20 can insulate the lower electrode plate 13, the piezoelectric element 14 and the upper electrode plate 15, which are objects to be insulated, and the metal shell 11 without gaps (without breaks), and the weight 17 It can be suppressed that metal powder generated during screwing or the like enters between the piezoelectric element 14 and the metal shell 11 through the gap and lowers the insulation. In addition, since the insulating member 20 is composed of one (one-piece) part, the number of parts can be reduced to reduce costs and improve productivity.

For example, as shown in FIG. 4, the lower electrode plate 13, the piezoelectric element 14, and the upper electrode plate 15 can be assembled to the insulating member 20.
First, the weight-side insulating portion 20b, which is one flange portion of the insulating member 20, is pulled upward in the direction of the arrow with a predetermined jig or the like (FIG. 4A), and the weight-side insulating portion 20b is an insulating cylinder portion. It is made to deform | transform so that 20c may be met (FIG.4 (b)).
Accordingly, the lower electrode plate 13, the piezoelectric element 14, and the upper electrode plate 15 are inserted into the insulating cylinder portion 20c in this order from above the weight side insulating portion 20b (FIG. 4C). Next, when the load on the weight side insulating portion 20b is removed, the weight side insulating portion 20b returns to its original shape due to the elastic force, and the lower electrode plate 13, the piezoelectric element 14, and the upper electrode plate 15 are assembled to the insulating member 20. (FIG. 4D).

  Instead of the weight-side insulating portion 20b, the flange-side insulating portion 20a, which is the other flange portion, is deformed along the insulating cylinder portion 20c, and the upper electrode plate 15, the piezoelectric element 14, and the lower electrode are formed from below. You may insert the board 13 in the insulating cylinder part 20c in this order. In this embodiment, the weight-side insulating portion 20b and the flange-side insulating portion 20a have the same shape, so that the lower electrode plate 13, the piezoelectric element 14, and the upper electrode plate 15 are inserted into the insulating cylinder portion 20c from either side. The insulating member 20 may be turned upside down after being inserted.

On the other hand, when the insulating member is made of a resin having low elasticity, it is difficult to bend the weight-side insulating portion and the heel-side insulating portion. Therefore, for example, as shown in FIG. 5, the lower electrode plate 13, the piezoelectric element 14, and the upper electrode plate 15 can be assembled to the resin insulating member 21.
First, only the buttocks side insulating part 21a is formed at the lower end of the insulating cylindrical part shaped material 20c, and a hat-shaped insulating member shaped material 21x is prepared (FIG. 5A). Then, the lower electrode plate 13, the piezoelectric element 14, and the upper electrode plate 15 are inserted through the insulating member shape member 21x in this order from above (FIG. 4B). Next, at the position of the arrow near the upper electrode plate 15, heat is applied to the insulating member material 21x to soften it (FIG. 4C), and the upper part of the insulating member material 21x is bent radially outward. Then, the weight-side insulating portion 21b is formed (FIG. 4D). Thereby, the lower electrode plate 13, the piezoelectric element 14, and the upper electrode plate 15 can be assembled to the insulating member 21.

  It goes without saying that the present invention is not limited to the above-described embodiments, and extends to various modifications and equivalents included in the spirit and scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Non-resonance type knocking sensor 10 Sensor main body 11 Main metal fitting 11A Metal fitting side cylindrical part 11B Metal fitting side collar 13 Lower electrode plate (buttock side electrode plate)
14 Piezoelectric element 15 Upper electrode plate (weight side electrode plate)
17 Weights 20, 21 Insulating members 20a, 21a Insulation side parts 20b, 21b Weight side insulating parts 20c, 21c Insulating cylinder part 20h Insulating member through hole 30 Resin molded body L Axial direction of insulating cylinder part

Claims (2)

A metal fitting including a metal fitting-side cylindrical portion formed in a cylindrical shape, and a metal fitting side flange extending radially outward from one end of the metal fitting-side cylindrical portion;
A piezoelectric element in which the metal fitting-side cylindrical portion is inserted into a through hole;
A weight that is inserted through the through hole into the metal part-side cylindrical part and is sandwiched with the piezoelectric element between the metal part side flange part; and
A collar side electrode plate disposed between the piezoelectric element and the metal fitting side collar;
A weight-side electrode plate disposed between the piezoelectric element and the weight;
An insulating member;
A sensor body having:
A resin molded body made of resin covering the sensor body;
A non-resonant knock sensor comprising:
The insulating member includes a cylindrical insulating cylinder portion through which the metal fitting-side cylindrical portion is inserted into a through hole, a flange-side insulating portion extending radially outward from an outer surface of the insulating cylinder portion, and A weight-side insulating portion that extends radially outward from the outer surface of the insulating cylindrical portion while being spaced apart from the flange-side insulating portion in the axial direction;
The insulating cylindrical portion is disposed between the metal fitting side cylindrical portion, the flange side electrode plate, the piezoelectric element, and the weight side electrode plate to electrically insulate them,
The flange side insulating portion is disposed between the metal fitting side flange and the flange side electrode plate, and electrically insulates between the metal fitting side flange and the flange side electrode plate,
The non-resonant knock sensor, wherein the weight-side insulating portion is disposed between the weight and the weight-side electrode plate, and electrically insulates between the weight and the weight-side electrode plate.   The non-resonant knock sensor according to claim 1, wherein the insulating member is made of rubber or resin.

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