JP2883012B2 - Three-way piezoelectric acceleration sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-way piezoelectric acceleration sensor, and more particularly to a three-way piezoelectric acceleration sensor capable of reducing the size of a structure while suppressing the influence of disturbance due to a cable.

[0002]

2. Description of the Related Art There is known a three-way piezoelectric acceleration sensor in which three acceleration detectors whose sensing axes are orthogonal to each other are integrally accommodated in a case member. FIG. 7 is a perspective view of a conventional three-way piezoelectric acceleration sensor. This acceleration sensor has a flat quadrangular prism-shaped case member 51, and is formed compact by providing acceleration detection sections 53 at three corners of four corners as viewed from the upper surface 52 thereof. The acceleration detectors 53 are formed integrally with a base 55 that supports a sensing unit (not shown), and the acceleration detecting units 53... One side 54,
Each of the bases 54 is orthogonal to the base 54 and is fixed via a respective base 55 pressed into the case member 51.

The outputs of the acceleration detectors 53 are respectively connected to connectors 56 via lead wires (not shown). That is, except for the acceleration detector 53 press-fitted from the upper surface 52, the output of the acceleration detectors 53 is led to the connectors 56 provided integrally on the outer surface of the bases 55. The output of the acceleration detecting unit 53 press-fitted from the upper surface 52 is led out to a connector 56 provided on the inclined surface 57 with a 45-degree inclined surface 57 at the corner formed by the side surfaces 54, 54. I have. A plug (not shown) connected to a cable (not shown) is
6 and output to an external processing device (not shown) connected to the other end of the cable, for example, a charge amplifier.

[0004]

Generally, in order to obtain a certain measurement accuracy in acceleration measurement, it is necessary to prevent the mass of the acceleration sensor from affecting the object to be measured. It is preferable that the mass is suppressed to at least 1/10 or less of the mass of the object to be measured. Therefore, the acceleration sensor is further downsized to cope with various objects to be measured.

However, when the acceleration sensor is further downsized, the base of the acceleration detecting section is also downsized, and the rigidity of the base is reduced. As a result, there is a problem in that the vibration of the cable transmitted to the base via the connector directly acts on the acceleration detection unit, and the detection accuracy is reduced.

[0006]

In order to solve the above-mentioned problems, a quadrangular prism case member is provided, and acceleration detection units are provided in three corners of four corners as viewed from the upper surface, respectively. In a three-way piezoelectric acceleration sensor having sensing axes perpendicular to each other in a sensing axis direction, an inclined surface is formed in the remaining one corner of the corner, and acceleration detecting portions are formed on the inclined surface and on both sides adjacent thereto. Are provided separately from the acceleration detector.

Preferably, the connector is mounted on the case by moving the connector toward the upper surface of the case, or a screw hole for mounting to the object to be measured is formed on the bottom surface of the corner provided with the connector. It is preferable to form a through hole in the direction, protect the internal wiring between the acceleration detecting unit and the connector, and fix a bush for passing the mounting bolt in the through hole.

[0008]

[Function] By providing a connector separately from the acceleration detecting unit in the case, the vibration of the cable transmitted through the connector acts on the case member having high rigidity, and is directly transmitted to the acceleration detecting unit. Because it has no effect,
Despite miniaturization, it is possible to avoid a decrease in detection accuracy.

When the connector is mounted on the case by moving it toward the upper surface of the case, the space between the object to be measured and the connector is ensured, so that the ease of connection and disconnection of the cable from the connector can be improved.

When a screw hole is formed in the bottom surface of the corner, the detachability of the three-way piezoelectric acceleration sensor with respect to the object to be measured can be ensured.

When the bush is provided, the degree of freedom in the mounting direction with respect to the object to be measured is ensured. Therefore, it is possible to flexibly cope with a change in the cable arrangement and the like, and since there is no restriction on the mounting direction when connecting or disconnecting the cable, the operability of connection and disconnection can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an exploded perspective view of a three-way piezoelectric acceleration sensor according to a first embodiment of the present invention, and FIG. 2 is a plan view of the three-way piezoelectric acceleration sensor.

The three-way piezoelectric acceleration sensor 1 according to the first embodiment includes a flat, square prism-shaped case member 2 made of lightweight, highly rigid titanium or the like.
The acceleration detectors 4 are provided in three corners of the three corners, respectively, and the sensitive axes of the acceleration detectors are arranged so as to be orthogonal to each other. An inclined surface 6 having the same inclination angle with respect to two side surfaces 5 and 5 adjacent to each other at the same corner portion is formed in the remaining one corner portion, and this inclined surface 6 and both side surfaces 5 and 5 are formed. , Respectively, are provided with connectors 7 for receiving the outputs of the acceleration detectors 4 and symmetrically arranged, and the bottom surface 2a is fixed to the object to be measured.

More specifically, the case member 2 has stepped holes 2b... At three corners of the three corners except for the corner on the side of the inclined surface 6 at the upper surface 3 and the two side surfaces 5, 5 toward the respective corners. The bases 8 of the acceleration detectors 4 are press-fitted into the large-diameter portions of the stepped holes 2b so that the direction of the sensing axis is fixed perpendicular to the respective surfaces. Also, at the corner on the side of the inclined surface 6, the inclined surface 6 and the side surfaces 5, 5 include:
A small-diameter hole 2c communicating with the stepped hole 2b is formed on the upper surface 3 side, and a lead wire (not shown) of the acceleration detecting section 4 is connected, and a connector 7 is connected to an opening of the small-diameter hole 2c. Press in and install.

The acceleration detecting section 4 has an annular shear-type piezoelectric element 9 for detecting acceleration at a projection 8a on the far side of the base 8 which is a large-diameter cylinder shown in FIG. Is provided in the annular shape of the mass member 10 for applying the shearing force, and is accommodated in the stepped holes 2b of the case member 2, and the acceleration of the measurement object transmitted through the case member 2 is transmitted in the respective sensitive axis directions. Detect accordingly.

The three-way piezoelectric acceleration sensor 1 configured as described above is efficiently miniaturized by arranging the acceleration detector 4 and the connector 7 in the case 2 having a limited volume (specifically, approximately 10 g square, 3 g), and the vibration of the cable transmitted through the connector 7 acts on the highly rigid case member 2.
Does not directly affect the detection accuracy, it is possible to avoid a decrease in detection accuracy.

In addition, since the connectors 7 are provided close to the upper surface of the case member 2, a distance from the surface of the object to be measured to the connector can be secured, and a space can be secured on the connection end side. Therefore, in the small-sized three-way acceleration sensor, it is possible to ensure good operability of connection and disconnection when the plug of the cable is screwed into the connector by finger.

The inclined surface 6 can be formed only on the periphery of the mounting portion of the connector 7, and may be inclined not only with respect to the side surface but also with respect to the upper surface. Similar functions and effects can be obtained. The case member can be made of beryllium, stainless steel, aluminum, or the like, and the bottom surface thereof is coated with ceramic, epoxy resin, metal oxide, or the like to electrically insulate the object from the object to be measured, thereby providing a ground. Loop noise can be cut off.

Further, by forming a mounting portion by providing a step on the periphery of the bottom surface, the resonance peak of the entire acceleration sensor can be moved, and an amplifier having a signal amplification unit housed in the base of the acceleration detection unit. It is also possible to use a built-in acceleration sensor.

Next, a three-way piezoelectric acceleration sensor according to a second embodiment of the present invention will be described. FIG. 3 is a plan view thereof. In this case, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The case member 12 of the three-way piezoelectric acceleration sensor 11 according to the second embodiment has an inclined surface 6 at one corner.
In the other two corners except for the diagonal side of the inclined surface 6, two side surfaces 15, 15 sandwiching the diagonal corner are brought close to each corner side to form a stepped screw hole 12.
b, 12b are formed symmetrically, and the stepped screw holes 12
The acceleration detectors 14 and 14 are screwed and fixed in the b and 12b so that the axes of the acceleration detectors 14 and 14 are orthogonal to each other. 7 to accommodate the wiring.

The acceleration detecting section 14 has a lead wire (not shown) disposed at an end of a projection 8a of a base 18 having a thread formed on the outer periphery, and an engagement hole 18a for screwing in the outer surface of the base 18. To form With such a configuration, it is possible to screw and fix the acceleration detection unit 14 to the case member 12 without twisting the lead wires while the lead wires are inserted through the wiring holes 12c and the connector holes 2c. Become. Therefore, the acceleration detecting section 14 can be easily attached and detached, thereby improving the maintainability of the acceleration detecting section 14.

A structure for mounting the above-described acceleration sensor to the object to be measured will be described. The bottom surface of the case member of the acceleration sensor is formed as a flat bottom and a double-sided adhesive tape is applied to the measurement object,
In addition to using an adhesive or the like to bond and fix, as shown in a perspective view of the screw-in type mounting structure in FIG.
To form Set screw 2 that can be screwed into this screw hole 21b
By fixing 2 to the measurement object A, the detachability of the acceleration sensor can be ensured. Incidentally, the screw holes in the bottom surface 21a are due to the fact that the connector 7 is provided close to the upper surface side of the case member 2 as described above, so that there is room for the screw holes in the case member 21.

Next, the mounting structure of the three-way piezoelectric acceleration sensor provided with the bush will be described. FIG. 5 is a perspective view, and FIG. 6 is a sectional view showing an attached state. A vertical through-hole 24a is formed at a corner of the case member 23 on the inclined surface 6 side, and the through-hole 24a is fitted with a flanged bush 25 by press fitting, and a mounting screw 26 is inserted into the hollow hole.
And screwed to the object A to be measured. The through hole 24 a has a stepped portion on the upper surface 24 side of the case member 23 for receiving a flange portion of the flanged bush 25, and further has an intermediate portion 24.
An annular space for wiring is formed on the outer periphery of the flanged bush 25 with b. Since the lead wires led to the connectors 7 from the acceleration detectors 14 are placed in the annular space, no external force acts directly on them.

In the mounting structure of the three-way piezoelectric acceleration sensor provided with the bush, the degree of freedom in the mounting direction of the acceleration sensor with respect to the object to be measured is ensured. Therefore, it is possible to flexibly respond to changes in cable layout,
Since there is no restriction on the mounting direction when connecting or disconnecting the cable, the operability of connection and disconnection can be improved.

In this embodiment, the bush 25 is press-fitted, but a screw portion is formed on the inner surface of the through hole, a screw is also formed on the bush, and the bush is screwed into the through hole. Good.

[0027]

As described above, in the three-way piezoelectric acceleration sensor according to the present invention, the connector is provided on the inclined surface of the case member and on the two side surfaces on both sides thereof separately from the acceleration detecting portion. Accordingly, the vibration of the cable transmitted via the connector acts on the case member having high rigidity, and does not directly act on the acceleration detecting section. Therefore, according to the present invention, a small three-way piezoelectric acceleration sensor with high detection accuracy can be realized.

When the connector is attached to the case with the connector positioned close to the upper surface, operability of connection and disconnection of the cable can be improved by securing a space between the object to be measured and the connector.

When a screw hole is formed in the bottom surface of the corner portion, the detachability of the three-way piezoelectric acceleration sensor with respect to the object to be measured can be ensured.

Further, when the bush is provided, the degree of freedom in the mounting direction with respect to the object to be measured is ensured, so that it is possible to flexibly cope with a change in the cable arrangement, and to operate the connection and disconnection of the cable. Performance can be improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a three-way piezoelectric acceleration sensor according to a first embodiment of the present invention.

FIG. 2 is a plan view of the three-way piezoelectric acceleration sensor.

FIG. 3 is a plan view of a three-way piezoelectric acceleration sensor according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a screw-in type mounting structure.

FIG. 5 is a perspective view of a bush type mounting structure.

FIG. 6 is a sectional view showing the state of attachment.

FIG. 7 is a perspective view of a conventional three-way piezoelectric acceleration sensor.

[Explanation of symbols]

1. Three-way piezoelectric acceleration sensor 2. Case member, 2a
... Bottom, 2b ... Stepped hole, 2c ... Small diameter hole, 3 ... Top surface, 4
... Acceleration detector, 5 ... Side, 6 ... Slope, 7 ... Connector, 8 ... Base, 8a ... Protrusion, 9 ... Piezoelectric element, 10 ...
Mass body, 11: three-directional piezoelectric acceleration sensor, 12: case member, 12b: stepped screw hole, 12c: wiring hole, 14
... acceleration detector, 15 ... side surface, 18 ... base, 18a ...
Engagement hole, 21 case member, 21a bottom surface, 21b screw hole, 22 set screw, 23 case member, 24a through hole, 24 top surface, 24b intermediate step, 25 bush with flange, 26 … Mounting screw, A… Object to be measured.

Claims (4)

(57) [Claims] An acceleration detecting section is provided in each of three corners of four corners as viewed from the upper surface of a case member having a quadrangular prism, and the sensing axes of the acceleration detecting sections are orthogonal to each other. In the three-directional piezoelectric acceleration sensor, a slope is formed at the remaining one corner of the corner of the case member, and a connector receiving the output of the acceleration detection unit is formed on the slope and on both sides adjacent to the slope. A three-directional piezoelectric acceleration sensor, which is provided separately from the detection unit. 2. The three-way piezoelectric acceleration sensor according to claim 1, wherein the connector is arranged near the upper surface of the case member. 3. The three-way piezoelectric acceleration sensor according to claim 1, wherein a screw hole for attaching to a measurement object is formed on a bottom surface of a corner portion provided with the connector. Type acceleration sensor. 4. The three-way piezoelectric acceleration sensor according to claim 1, wherein the corner provided with the connector includes:
A three-way piezoelectric element characterized in that a vertical through-hole is formed in the case member to protect the internal wiring between the acceleration detector and the connector, and that a bush for passing a mounting bolt is fixed in the through-hole. Type acceleration sensor.