JPH0763603A - Vibration sensor - Google Patents

Abstract

PURPOSE:To provide a vibration sensor of superior workability in assembly. CONSTITUTION:In a sensor housing 2, a hole 4, with which a cap is engaged, is formed, following a caulked part 3 formed in the upper end part of the housing 2, and a shaft part 5 is formed into one body in the center of the hole 4. A male screw 6 is provided in the end part of the shaft part 5. On the shaft part 5, an insulator 8 is first mounted. The cylindrical body 10 of the insulator 8 is inserted into an electrode plate 11 on the lower side, piezoelectric element 15, electrode plate 17 on the upper side, ring-like insulator 21, weight 22 and wave washer 23, in the order thereof, a locknut 24 is engaged with the male screw 6, and their parts are put between the housing 2 and the washer 23. By forming a female screw in the weight 22, the locknut 24 can be omitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration sensor for converting mechanical vibration into an electric signal by a piezoelectric element sandwiched in a sensor housing and taking it out from a terminal.

[0002]

2. Description of the Related Art A knocking sensor in which an annular piezoelectric element as described in Japanese Patent Laid-Open No. 2-218927 is inserted together with a weight into a mounting bolt and the mounting bolt is screwed and fixed to a case is disclosed in Japanese Utility Model Laid-Open No. 58-180427. It is disclosed in the publication.

[0003]

When assembling the knocking sensor, the inserted piezoelectric element, weight, etc. are supported so as not to fall out, and the mounting bolt is inverted and screwed into the case, so that the workability of assembly is improved. There was a problem that it was bad and inefficient. The present invention has been made to solve the above problems, and an object of the present invention is to provide a vibration sensor having excellent workability in assembly.

[0004]

In order to achieve the above object, a vibration sensor of the present invention is a vibration sensor for converting mechanical vibration into an electric signal by a piezoelectric element sandwiched in a sensor housing and taking it out from a terminal to the outside. A shaft portion is integrally formed with the sensor housing, a male screw is provided at a tip end portion, at least the piezoelectric element and the weight are inserted into the shaft portion, and clamped by a tightening nut screwed with the male screw. And

[0005]

At least the piezoelectric element and the weight of the vibration sensor having the above construction are inserted into the shaft portion integrally formed with the sensor housing, and the male screw formed at the tip of the shaft portion is tightened by tightening the tightening nut. It is pinched by. The tightening nut can be omitted by screwing the weight-formed female screw into the male screw.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of the vibration sensor 1. As shown in FIG. 1, the sensor housing 2 has a caulking portion 3 formed at an upper end portion thereof, and a cap fitting hole 4 continuous with the caulking portion 3, and a shaft portion 5 is integrally formed at the center of the cap fitting hole 4. A male screw 6 is provided at the tip of the shaft portion 5. Then, a mounting male screw 7 protruding from the bottom surface of the sensor housing 2 is formed.

An insulator 8 is first attached to the shaft portion 5. As shown in FIG. 2, the insulator 8 is formed of an insulating ring-shaped base 9 mounted in the cap fitting hole 4 and an insulating cylindrical body 10 that covers the outer periphery of the shaft portion 5. Then, the lower electrode plate 11, the piezoelectric element 15, the upper electrode plate 17, the ring-shaped insulator 21, the weight 22, and the wave washer 23 are inserted into the cylindrical body 10 in this order, and the male screw 6 at the tip is tightened with a tightening nut. 24 is screwed and clamped.

FIG. 3 is a perspective view of the lower electrode plate 11, the piezoelectric element 15 and the upper electrode plate 17. Lower electrode plate 11
The terminal connecting portion 13 is formed on the ring-shaped conductive metal plate 12, and the terminal connecting portion 13 is provided with the contact protrusion 14. The piezoelectric element 15 is a disk-shaped P having a shaft insertion hole 16 in the center.
It is a ZT element and is uniformly polarized in the thickness direction. Further, the upper electrode plate 17 is bent downward from the ring-shaped conductive metal plate 18 and further provided with a terminal connecting portion 19 which is bent in the opposite direction to be in a horizontal posture. A contact portion 20 is provided. Ring-shaped insulator 21
Insulates the upper electrode plate 17 from the weight 22. The contact protrusion 14 of the lower electrode plate 11 and the contact protrusion 20 of the upper electrode plate 17 are positioned so as to face each other in the radial direction.

The cap 25 fitted in the cap fitting hole 4 has a cap portion 26, a flange portion 27 and a connector connecting portion 28 integrally formed by resin molding. A pair of terminals 29a and 29b bent along the shape of the cap portion 26 are embedded. Terminals 29a, 29
Reference numeral b denotes a contact portion 30a, 30b formed by projecting one end into the connecting recess 28a of the connector connecting portion 28 and forming the other end at the tip.
Are opposed to each other in the radial direction and are exposed at the lower end of the cap portion 26. The cap 25 has an O-ring 3 at the lower end of the flange 27.
1 and the caulking portion 3 of the sensor housing 2 is caulked and fitted into the flange portion 27. However, the abutting portion 30 can be positioned by using a positioning protrusion (not shown) or the like.
a and 30b are the lower electrode plate 11 and the upper electrode plate 1
The contact projections 14 and 20 of 7 are respectively contacted.

In the vibration sensor 1 having the above structure, the shaft portion 5 is integrally formed with the sensor housing 2, so that the mounting bolt is not necessary. Therefore, at the time of assembling, the insulator 8, the lower electrode plate 11, the piezoelectric element 15, the upper electrode plate 17, the ring-shaped insulator 21, the weight 22, the wave washer 23, etc. are inserted into the mounting bolts, and their respective parts fall out. It is possible to omit the step of reversing and screwing into the sensor housing 2 so that
The one-way assembly has advantages such as improved workability and automation. Also, the terminals 29a, 2
9b projecting into the connecting recess 28a of the connector connecting portion 28 and the contact portion 30 exposed at the lower end of the cap portion 26.
Except for a and 30b, since they are embedded in the cap portion 26, vibration of the terminals is suppressed during vibration detection, and the contact portions 30a and 30b and the lower and upper electrode plates 11 and 17 contact protrusions. There is an advantage that the contact with the parts 14 and 20 can be secured and the reliability of the vibration sensor can be improved.

FIG. 4 is a sectional view of a vibration sensor 41 showing a modification of the first embodiment. Similar to the first embodiment, first, the insulator 48 is attached to the shaft portion 45 integrally formed with the sensor housing 42. And the insulator 48
The lower electrode plate 51, the piezoelectric element 55, the upper electrode plate 57, the ring-shaped insulator 61, the weight 6 are attached to the tubular portion 50 of the
2 in order, and tighten the nut 64 onto the male screw 46 at the tip.
It is screwed and clamped. The lower electrode plate 51 and the upper electrode plate 57, which are arranged in contact with both surfaces of the piezoelectric element 55, respectively, are made of a conductive metal plate and have a ring-shaped electrode portion 5 as shown in FIG.
1a and 57a and linear terminal portions 51b and 57b are punched out, and the terminal portions 51b and 57b are bent and formed.

The sensor housing 42, in which the respective parts are assembled as described above, is set in a resin molding die (not shown), and resin molding is performed by embedding the respective parts by molding. Then, the tips of the terminal portions 51b and 57b are projected into the connecting recess 72a of the connector connecting portion 72 integrally formed with the resin sealing portion 71.

In the vibration sensor 41 having the above structure, the lower electrode plate 51 and the upper electrode plate 57 are formed by a conductive metal plate in which the ring-shaped electrode portions 51a and 57a and the strip-shaped terminal portions 51b and 57b are punched out. At the same time, since it is molded by resin sealing, the wave washer for preventing the tightening nut 64 from loosening can be omitted, and there is an advantage that not only the number of parts but also the number of assembling steps can be reduced.

Further, as shown in FIG. 7, the electrode plate 77 placed in contact with either the upper surface or the lower surface of the piezoelectric element 75 (FIG. 6) in which the polarization directions applied in the thickness direction are opposite to each other as shown in FIG. Shaped arcuate electrode portion 77a and linear terminal portion 7
7b is punched out, and the terminal portion 77b is bent and formed.
The cross-sectional shape of the shaft portions 5 and 45 in each of the above embodiments may be not only circular but also polygonal.

FIG. 8 is a sectional view showing a second embodiment of the present invention. The components and parts of the vibration sensor 100 that are substantially the same as those of the first embodiment in terms of configuration and operation are denoted by the same reference numerals, detailed description thereof will be omitted, and different parts will be described below. The shaft portion 105 integrally formed at the center of the cap fitting hole 4 has a hexagonal cross section, and a male screw 106 is formed from the middle portion to the tip portion. Insulator 1
Reference numeral 08 is composed of a hexagonal insulating tubular body 110 which is fitted onto the shaft portion 105, and an insulating base 109 which is inserted into the tubular body 110 and covers the entire bottom surface of the fitting hole 4. It

The cylindrical body 110 includes a lower electrode plate 11, a piezoelectric element 15, an upper electrode plate 17, and a ring-shaped insulator 2.
1, the spacer 122 is inserted in this order, and the male screw 10 at the tip is inserted.
A female screw 124 formed on the weight 123 is screwed onto the screw 6, and the weight 123 is tightened to clamp the above-mentioned components. To tighten the weight 123, use a tightening tool (not shown) for the weight 12.
It is carried out by inserting it into the third fastening hole 123a. The hole shapes of the ring-shaped conductive metal plates 12 and 18 of the lower electrode plate 11 and the upper electrode plate 17 are hexagonal, and by inserting the hexagonal cylindrical body 110, the contact protrusion 14 is formed. And the contact protrusion 20 are positioned so as to face each other in the radial direction. The hole shapes of the ring-shaped insulator 21 and the spacer 122 are also hexagonal.

A metal ring 130 having an inwardly facing flange 131 is embedded in the cap portion 26 of the cap 25 fitted in the cap fitting hole 4. The outer circumference 132 of the metal ring 130 is flush with the outer circumference of the cap portion 26 and is exposed. Further, a 0 ring mounting step 133 is formed on the cap portion 26, and a 0 ring 134 is mounted on the cap portion 26. After a ring-shaped spacer 135 made of an insulating resin was fitted on the inner circumference of the bottom of the cap fitting hole 4, the cap 25 was fitted into the cap fitting hole 4 and exposed at the lower end of the cap portion 26 to be opposed in the radial direction. The contact portions 30a and 30b of the terminals 29a and 29b are brought into contact with the contact protrusions 14 and 20 of the lower electrode plate 11 and the upper electrode plate 17, respectively. Then, the washer 136 fitted to the cap portion 26 and brought into contact with the O-ring 134 is caulked by the caulking portion 3 and fitted.

The vibration sensor 100 having the above structure has the same advantages as the vibration sensor 1 of the first embodiment described above, and since the weight 123 is formed with the female screw 124, the tightening nut can be omitted, and the number of parts can be further reduced. Reduction is possible. In addition, the metal ring 13 embedded in the cap portion 26
The outer periphery 132 of the cap portion 26 is flush with the outer periphery of the cap portion 26 and is exposed.
It can be fitted tightly without rattling. Therefore, the transmitted vibration does not cause the cap 25 itself to vibrate to cause a disturbance in the vibration detection signal, and the reliability of vibration detection can be improved.

The vibration sensors 1, 41 and 1 of the above embodiments
00 is used as a knocking sensor by mounting the mounting male screw 7 on the engine block 81 by screwing it into the engine block 81 as shown in FIG. The vibration of the engine is converted into an electric signal according to the vibration by the piezoelectric element and taken out by the wire harness 82 connected to the connector connecting portion,
It is input to the electronic control unit 83. In the electronic control unit 83, the electric signal is arithmetically analyzed by a predetermined program, knock determination processing is performed, and an ignition timing control signal is output.

[0020]

As described above, according to the vibration sensor of the present invention, at least the piezoelectric element and the weight are inserted into the shaft portion integrally formed in the sensor housing, and the nut is screwed onto the male screw formed at the tip of the shaft portion. Since it is sandwiched by tightening together, it is possible to omit the work of reversing the mounting bolt and screwing it into the sensor housing so that the piezoelectric element and weight inserted in the mounting bolt do not fall out, and one-way assembly is possible Therefore, there is an effect that the efficiency of the assembling work can be improved and the automation can be realized. In addition, the weight formed female screw is screwed into the male screw, so that the tightening nut can be omitted, and the working efficiency of the assembling can be further improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a vibration sensor according to a first embodiment.

FIG. 2 is a perspective view of an insulator.

FIG. 3 is a perspective view of lower and upper electrode plates and a piezoelectric element.

FIG. 4 is a sectional view of a vibration sensor showing a modified example of the first embodiment.

FIG. 5 is a plan view of an electrode plate.

FIG. 6 is a perspective view showing a polarization direction of a piezoelectric element.

FIG. 7 is a plan view of an electrode plate.

FIG. 8 is a sectional view of a vibration sensor according to a second embodiment.

FIG. 9 is a schematic view showing a usage mode of the vibration sensor.

[Explanation of symbols]

 1, 41, 100 ... Vibration sensor 2, 42 ... Sensor housing 5, 45, 105 ... Shaft part 6, 46, 106 ... Male screw 15, 55, 75 ... Piezoelectric element 22, 62,123 ... weight 24,64 ... tightening nut 124 ... female screw

Claims (2)

[Claims] 1. A vibration sensor for converting mechanical vibration into an electric signal by a piezoelectric element sandwiched in a sensor housing and taking it out from a terminal to the outside, wherein a shaft portion is integrally formed with the sensor housing and a male screw is provided at a tip portion thereof. A vibration sensor, wherein at least a piezoelectric element and a weight are inserted into the shaft portion and are clamped by a tightening nut screwed with the male screw. 2. The vibration sensor according to claim 1, wherein the tightening nut is omitted by screwing the weight-formed female screw into the male screw.