JPS5929820B2 - Three-way detection type acceleration pick-up - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-directional detection type acceleration pickup that simultaneously detects x, y, and 2 components of vibration.

This invention couples two mass bodies through a first shear effect type piezoelectric element, and provides at least one portion of the upper and lower surfaces of one of the mass bodies.
The two surfaces are connected to the case via second and third shear effect type piezoelectric elements whose polarization directions are perpendicular to each other, and these piezoelectric elements detect the three-directional components of acceleration separately.
It is significantly smaller and lighter than the conventional three-directional detection pickup configured by combining three pickups, and it is also easy to align the center of gravity of the pickup body with the center of gravity of the mass body, which eliminates complications caused by misalignment of the center of gravity. It is characterized by the fact that resonance can be suppressed and it is easy to design the sensitivity in each direction to be the same.

FIG. 1 shows a first embodiment of the present invention, where Cl is an annular first piezoelectric element, C2 and Cs are plate-shaped second and third piezoelectric elements, and the direction of the arrow (Cs is perpendicular to the paper)
They are all shear effect type piezoelectric elements.

0 Electrodes E1 and E are provided on the inner and outer surfaces of the piezoelectric element Cl, respectively, and the outer surface of Cl and the inner surface of the annular mass body M1 are connected, and the inner surface of Cl is connected to the side surface of the cylindrical mass body M2. By coupling, the mass bodies M1 and M2 are concentrically arranged side by side.

Electrodes E are provided on the upper and lower surfaces of the piezoelectric elements 5C2 and Cs, respectively.
2, E2', Es, Es' are provided, and piezoelectric elements C2, Cs
have one surface coupled to the top and bottom surfaces of the cylindrical mass body M2, and the other surface coupled to the inner top surface and inner bottom surface of the annular case B with a bottom and a lid via electrical insulators Zl and Z2. . L is a ground conductor. To explain the operation of the device with the above configuration, as shown in Fig. 2a, when acceleration is applied to the pickup in the z direction, a shearing force acts on the piezoelectric element C1 due to the vertical movement of M1, and the electrode E
An output is obtained between l and EV.

At this time, compression and tension forces act on the piezoelectric elements C2 and C3, but no shear force acts on the piezoelectric elements C2 and C3.
There is no output from . On the other hand, when acceleration in the x direction (or y direction) is applied, the piezoelectric element C
2. A shearing force acts on C3, and an output is obtained between the electrodes of the piezoelectric element whose polarization direction matches the direction of acceleration.

In the figure, an output is obtained between the two electrodes E2 and E'2' of the piezoelectric element C2, but since the polarization direction of the piezoelectric element C3 is perpendicular to the direction of acceleration, there is no output between the electrodes E3 and E3'. Also,
For the same reason, there is no output from the piezoelectric element C1. For acceleration in any direction, outputs proportional to the X, y, and z components of the acceleration vector are obtained between the electrode pairs provided at C2, C3, and Cl, respectively. Letting the charge sensitivities of the vibrations of this pickup in the X, y, and z directions to be Qx, Qy, and Qz, respectively, in the case of a comparatively low frequency, they are approximately as shown below.

Here, Dl5 is a piezoelectric constant, and αX, αY, and αz represent acceleration components in the X, y, and z directions, respectively. Therefore, X, y,
In order to make the charge sensitivity of each component of z the same, it is sufficient to set M1=M2. FIG. 3 shows the embodiment of FIG. 2, in which the outer surface of the piezoelectric element C1 and the inner surface of the annular mass body M1 are coupled, and C
The inner surface of M2 is connected to the side surface of the cylindrical mass M2.

Each of the piezoelectric elements C2 and C3 has one surface coupled to the lower surface of the cylindrical mass M2, and the other surface coupled to the inner bottom surface of the annular case B via an electrical insulator Z. Electrode EZ
, E3' are electrically insulated from each other. Figure 4 shows
In the third embodiment, the mass body M2 is fixed to the case B with a screw N. The diameter of the cylindrical hole provided in the mass body M2 is larger than the diameter of the screw N, and the mass body M2 is fixed to the case B with a screw N. It is designed so as not to obstruct the movement of M2.

The other configurations are the same as in FIG. 3. In the fourth embodiment shown in FIG. 5, the mass body M1 is provided inside the piezoelectric element C1,
A bottomed annular mass M2 is coupled to the outer surface of the piezoelectric element C1. The piezoelectric elements C2, C3 and the mass body M2 are connected to the case B via the insulating material Z, as in the case of FIG. Figures 6a, 6b and 6c show the arrangement rows of piezoelectric elements C2 and C3.

Figure 6a shows one C2 and one C3, and Figure 6b shows C2.
, C3 are divided into a plurality of pieces, FIG. 6c shows a case where the disc-shaped piezoelectric element is divided into two parts, and the polarization directions of the two parts are orthogonal to each other. In either case, in order to make the sensitivity in the X and y directions the same, C2 and C3 need to have the same thickness and the same area. Furthermore, as shown in FIG. 7, piezoelectric elements C2 and C3 are coupled via an insulator Z, and outputs of x and y components are obtained from electrodes EZ and E3 that are in contact with the upper and lower surfaces of the insulator Z, respectively.

FIG. 8 shows a fifth embodiment in which a plate-shaped piezoelectric element is used instead of an annular piezoelectric element for detection in the z-direction.

However, the structure of the mass bodies Ml, M2 and the piezoelectric elements Cl, C2, C3 is shown, and the outer case is not shown. C1 has two or four pieces polarized in the direction of the arrow, electrodes are provided on one pair of planes parallel to the direction of polarization, and the two or four pieces of C1 are connected to two or four sides of the prismatic mass body M1, and a U-shaped structure is formed around it. A circular or square annular mass M2 is connected. The plate-shaped piezoelectric elements C2 and C3, each polarized in the direction of the arrow, are also provided with electrodes on a pair of surfaces parallel to the polarization direction, and the mass body M2 and the case are coupled via these. The operating principle is the same as that using the annular piezoelectric element described above.

FIG. 9 shows a modification of the configuration of piezoelectric elements C2 and C3, in which piezoelectric element C2 is formed by joining two elements C2a and C2b polarized in opposite directions, and piezoelectric element C3 is formed by joining two elements C2a and C2b polarized in opposite directions. element C3a polarized perpendicularly to C2 at
and C3b.

In this way, outputs can be extracted from the intermediate portions of the two elements, and there is no need to interpose an insulator between the mass body M2 and the case B. As described above, the present invention has great industrial benefits, such as being able to detect acceleration in each of the three directions with a simple and compact configuration, and furthermore, it is easy to design the sensitivity in the three directions to be the same.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a front sectional view of the first embodiment of the present invention, FIG. 2a,
FIG. 2b is an explanatory diagram of the operation, FIG. 3 is a front sectional view of the second embodiment, FIG. 4 is a front sectional view of the third embodiment,
Figure 5 is a front sectional view of the fourth embodiment, Figure 6a, and Figure 6.
Figures b and 6c are respectively plan views showing examples of the arrangement of piezoelectric elements, Figure 7 is a partial front sectional view showing an example of the arrangement of piezoelectric elements, and Figure 8 is a perspective view of the main part of the fifth embodiment. 9A and 9B are partially front sectional views of other embodiments of the same configuration of the piezoelectric element. Ml, M2: mass body, Cl, C2, C3: piezoelectric element, E
l, EV, E2, E2', E3, E3': electrode, Z, Z
l, Z2: Electrical insulator, B: Case, L: Earth conductor.

Claims (1)

[Claims] 1. Mass bodies M1 and M2 arranged concentrically are coupled by a first piezoelectric element C1 of shear effect type, and at least one of the upper and lower surfaces of the mass body M2 and the case B are connected. The first piezoelectric element C is of a shear effect type and has polarization directions perpendicular to each other.
2nd and 3rd piezoelectric elements C2 and C3 perpendicular to the polarization direction of 1;
A three-directional detection type acceleration pickup characterized by being combined with. 2. The device according to claim 1, wherein the mass body M1 is annular, the mass M2 is cylindrical, and the piezoelectric element C1 is annular. 3 Piezoelectric element C2 is placed between the bottom surface of mass body M2 and the bottom surface of case B.
, C3 are coupled in juxtaposition. 4. The device according to claim 1, wherein the mass body M2 and the case B are connected by a screw N that loosely fits into the mass body M2. 5 The mass body M2 is annular with a bottom, and the annular piezoelectric element C
2. The device according to claim 1, wherein the mass body M1 is coupled to the inside of the mass body M2 through a mass body M1. 6 Piezoelectric element C2 is placed between the bottom surface of mass body M2 and the bottom surface of case B.
, C3 are stacked and bonded together. 7. The device according to claim 1, wherein the piezoelectric element C1 comprises a plurality of plate-shaped piezoelectric elements. 8. The device according to claim 1, wherein the piezoelectric elements C2 and C3 are constructed by overlapping and bonding a pair of elements each polarized in opposite directions.