JPH0244217Y2 - - 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 in the means for connecting and fixing the piezoelectric element to a support body and a mass body, and its main purpose is to improve the ease of manufacturing and assembly. The point is to ensure that

The shear type acceleration pickup utilizes the sliding strain that occurs in a piezoelectric element that is fixedly connected to a support body and a mass body that protrude from the base when the base vibrates, and the method of this connection and fixation is important. It is.

However, the means usually employed to connect the piezoelectric element to the support body and the mass body is adhesive bonding, but the adhesive peels off due to aging and is insufficient in terms of mechanical strength. It 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 will be explained with reference to FIGS. 1A and 1B. Reference numeral 1 denotes a pair of piezoelectric elements having a through hole 1A in the center, and after polarization treatment, electrodes are provided on each pair of surfaces parallel to the polarization direction (arrow), and the pair of piezoelectric elements 1 with the polarization directions aligned , 1 are attached to the base 2 on both sides of the support 3 protruding from the base 2.
and are arranged opposite to each other. 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 base 2 on the outside of each of the pair of piezoelectric elements 1, 1 and also separately from the base 2. 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; It is tightened at 6,6. Therefore, the piezoelectric element 1 is held between the support body 3 and the mass body 4, and the three 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 had to be assembled carefully so that they were located in the center of the through holes 1A and 3A, which caused difficulties 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, 11 are disposed on both sides of this support 13, facing each other and separated from the base 12. Reference numeral 14 denotes a holding plate that is disposed facing each other on the outside of the pair of piezoelectric elements 11, 11, respectively. Due to the presence of this presser plate 14, it engages with the piezoelectric element 11 in a face-to-face relationship, and as a result, shearing force can be applied to the piezoelectric element 11. Therefore, the piezoelectric element 11 is held between the support body 13 and the press plate 14. 1
Reference numeral 5 denotes a cylindrical mass body having an accommodation space 15A for accommodating the support body 13, the piezoelectric element 11, and the presser plate 14 therein, and is disposed apart from the base 12. Reference numeral 16 designates a pair of coupling and fixing members such as bolts, which are inserted into opposing through holes 15B formed symmetrically and coaxially from the center of the mass body 15 on the side surface of the mass body 15;
The tip presses the presser plate 14. Therefore, piezoelectric element 1
1, the support body 13, and the mass body 15 are fixed together.

In this embodiment, the mass body 15 is formed in a cylindrical shape considering that pick-up cases are generally formed in a cylindrical shape for ease of processing. It is subject to change. Further, in this embodiment, a pair of piezoelectric elements have been described, but the present invention is not limited to this, and a plurality of piezoelectric elements may be stacked and used.

In this structure, the total mass of the mass body 15 and the coupling and fixing member 16 is 8.4 g, and the piezoelectric element 11 has an electrode size of 5 mm x 5 mm, a thickness of 1 mm, and a capacity.
When using a 260PF one, the output sensitivity is 42mv/
g was obtained, and there was no practical problem. In this case, the piezoelectric element was made of PZT, and the mass body and others were made of stainless steel.

As described above, the present invention accommodates and arranges the piezoelectric elements, which are arranged opposite to each other via the support body protruding from the base, in the housing space of the mass body, and connects and fixes the piezoelectric elements from the side surface of the mass body via the holding plate. By pressing the piezoelectric element with the piezoelectric element, the support body, the piezoelectric element, and the mass body are coupled and fixed. Therefore, it is not necessary to provide through-holes not only in the support but also in the piezoelectric element itself, which is advantageous in that manufacturing can be simplified and the capacitance of the piezoelectric element does not decrease. Furthermore, the absence of the through hole makes manufacturing and assembly extremely easy.

[Brief explanation of the drawing]

FIG. 1A is a side sectional view showing a conventional example. FIG. 1B is also a plan view thereof. FIG. 2A is a side sectional view showing an embodiment of the present invention. FIG. 2B is also a plan view thereof. 11: piezoelectric element, 12: base, 13: support body, 14: presser plate, 15: mass body, 15A: housing space, 16: coupling and fixing member.

Claims (1)

[Claims for Utility Model Registration] A base 12 having a protruding support 13, a piezoelectric element 11 disposed facing each other with the support 13 in between and separated from the base 12, and further outside the piezoelectric element 11. A housing space 15A in which the presser plates 14, the support body 13, the piezoelectric element 11, and the presser plate 14 are formed inside.
and a cylindrical mass body 15 that is housed in and disposed in the base and is free from the base, and a pair of coupling and fixing members 16 that face each other and pass through the side surfaces of the mass body 15.
4, each piezoelectric element 11 is connected to the support body 13 through
A shear type acceleration pick-up in which the piezoelectric element 11, support body 13, and mass body 15 are coupled and fixed by pressing.