JPS6116528Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an improvement of a shear-type acceleration pick-up that utilizes a piezoelectric element, and in particular to an improvement of the means for coupling and fixing the piezoelectric element to a mass body.The purpose of this invention is to primarily ensure ease of manufacturing and assembly. At the point.

The shear type acceleration pickup utilizes the sliding strain that occurs in a piezoelectric element that is fixedly coupled to a support body that protrudes from the base and a mass body when the base vibrates, and the method of this coupling and fixing is important. It is. However, the bonding method that is usually used to connect the piezoelectric element to the support and mass body is adhesive bonding, but it is insufficient in terms of mechanical strength, such as peeling of the adhesive due to aging. , had some problems. On the other hand, a method has been proposed in which a through hole is provided in the piezoelectric element, the support body, and the mass body, and the three are fastened and fixed together with bolts through the through hole. This conventional example is shown in Figure 1A.
This will be explained along with FIG. 1B. Reference numeral 1 denotes a pair of piezoelectric elements having a through hole 1A in the center thereof, and after polarization treatment, electrodes are provided on each of a pair of surfaces parallel to the polarization direction (arrow). This pair of piezoelectric elements 1, 1 having the same polarization direction are placed opposite to each other with a support 3 protruding from a base 2 interposed therebetween. Note that 3A is a through hole formed in the support body 3. Reference numeral 4 denotes a mass body having a through hole 4A in the center thereof, and is disposed opposite to the outside of the pair of piezoelectric elements 1, 1, respectively. 5
is a bolt that passes through the through holes 4A, 4A of the pair of mass bodies 4, 4, the through holes 1A, 1A of the pair of piezoelectric elements 1, 1, and the through hole 3A of the support body 3, and both ends thereof are connected to nuts 6. ,6 is tightened. Therefore,
The piezoelectric element 1 is held between a support body 3 and a mass body 4,
The three parts are connected and fixed with bolts. To explain the action, the base 2 vibrates and the support 3 moves together as a unit, and the mass body 4 exhibits the function of a pendulum, causing a sliding motion to act on the piezoelectric element 1, producing an output. That will happen.

Although the piezoelectric element is certainly firmly connected to the support and the mass body in the conventional configuration described above, it is necessary to provide a through hole not only in the support but also in the piezoelectric element. Therefore, the piezoelectric element is easily broken, and the capacitance decreases only at the through hole. Furthermore, when the bolt and the support or the piezoelectric element come into contact, the base and the mass become integrated,
No sliding movement occurs in the piezoelectric element. Therefore, the bolts must be assembled carefully so that they are located in the center of the through holes 1A and 3A, which poses a difficulty in manufacturing and assembly.

In view of the above drawbacks, the present invention provides a sufficiently strong coupling and fixing means using a piezoelectric element having no through holes.

An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 2A and 2B, reference numeral 11 denotes a piezoelectric element having electrodes provided on a pair of surfaces parallel to the polarization direction (arrow) after polarization treatment. 13 is a support body protruding from the base 12. A pair of piezoelectric elements 11 and 11 are arranged opposite to each other with this support 13 in between. 14 is a pair of piezoelectric elements 11, 1
The mass bodies are arranged facing each other outwardly from each other. The mass body 14 includes a main body 14A that comes into contact with the piezoelectric element 11, and coupling ends 14B provided at both ends of the main body 14A. One joint end 1
4B has a coupling through hole 15A through which a coupling fixing member 15 such as a bolt passes, and the other coupling end 14B has a coupling blind hole 15B through which the coupling fixing member 15 is screwed.
is formed. 15C is the head of the coupling and fixing member 15. Regarding the pair of mass bodies 14, the reason why the coupling blind holes 15B and the coupling through holes 15A are formed alternately is to prevent the pair of mass bodies 14 from becoming unbalanced. Further, in this embodiment, one of the joint end portions 14B is made into a blind joint hole 15B, but it does not necessarily have to be a blind hole, and the joint fixing member 15 such as a bolt passed through the hole may be tightened with a nut. The following effects can be obtained. In short, it is sufficient that the pair of mass bodies 14 can be firmly connected to each other by the connecting fixing member 15. Furthermore, in this embodiment, the outer shape of the mass body 14 is formed into an arc shape considering that pick-up cases are generally formed into a cylindrical shape for ease of processing. It is subject to change.
That is, as shown in FIG. 3, the outer shape of the mass body 14 can be configured to be substantially quadrilateral, so that it can be adapted to the case where the pickup case is cubic. Furthermore, the number of piezoelectric elements 11 need not be limited to one pair, and a desired number can be installed.

In this configuration, the total mass of the mass body 14 and the coupling and fixing member 15 is 6 gγ, the piezoelectric element 11 has electrode dimensions of 5 mm x 5 mm, thickness of 1 mm, and capacity.
When using a 260PF one, the output sensitivity is 30mv/
g was obtained, and there was no practical problem. In this case, the piezoelectric element was made of PZT, and the mass body, base, and support were made of stainless steel.

As described above, in the present invention, the piezoelectric element is held between a pair of mass bodies and a support body, and the piezoelectric element and the mass body are coupled and fixed by connecting both ends of the pair of mass bodies. Therefore, there is no need to provide a through hole in the piezoelectric element itself, the mechanical strength is maintained sufficiently, and there is no decrease in capacitance, which is advantageous.
Furthermore, it can be easily connected and fixed, making manufacturing and assembly extremely easy.

[Brief explanation of the drawing]

1A is a side sectional view showing a conventional example, FIG. 1B is a plan view, FIG. 2A is a partially sectional side view showing an embodiment of the present invention, and FIG. 2B is a plan view,
FIG. 3 is a plan view showing another embodiment. 11: piezoelectric element, 12: base, 13: support body, 14: mass body, 14A: main body, 14B: joint end, 15: joint fixing member.

Claims (1)

[Claims for Utility Model Registration] First, piezoelectric elements 11, 11 are disposed facing each other with a support 13 protruding from a base 12, and a pair of mass bodies 14, 14 are further disposed facing each other, wherein said mass body 14 is composed of a main body 14A that comes into contact with the piezoelectric element 11, and coupling ends 14B formed at both ends of the main body 14A, and both of the pair of mass bodies 14 are coupled at the coupling ends 14B. A shear type acceleration pick-up which is connected and fixed by a fixing member 15.