JPH0666828A - Vibration type acceleration meter - Google Patents

Abstract

PURPOSE:To prevent the rupture of a vibrator and the peeling of the fixed portion due to environmental temperature change. CONSTITUTION:A pendulum 21, a frame 22 arranged around its outer periphery and a hinge 23 to connect these are integrally formed with the same material. A vibrator 15 has one end fixed to the pendulum 21 via a spacer 26 and the other end extended to the side of the frame 22, where the pendulum 21 is connected, and fixed to one end of a support 27 which is made of material with the thermal expansion coefficient almost equal to that of the vibrator 15. The support 27 has the other end fixed to both sides of the frame 22 at a position corresponding to one end of the vibrator 15. The expansion amounts of the vibrator 15 and the support 27 due to temperature change are almost equal and so thermal stress seldom occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration type accelerometer using a vibrator as a detecting means.

[0002]

2. Description of the Related Art The structure of a conventional vibration type accelerometer 10 of this type is shown in FIG. A frame body 12 is arranged on the outer periphery of the plate-like pendulum 11 in the plate surface direction, and one end of the pendulum 11 is connected to the frame body 12 via a hinge 13. The pendulum 11, the frame 12 and the hinge 13 are integrally formed of, for example, a plate-like body, and the hinge 13 has a reduced thickness and is elastically deformable. The hinge 13 bends with its connecting surface with the frame 12 as a fixed end, so that the hinge 13 parallel to the width direction of the fixed end.
The pendulum 11 is rotatable around the hinge 13 with the axis center of the as the rotation axis 14.

One end 15a in the longitudinal direction of a substantially strip-shaped vibrator 15 whose both ends in the longitudinal direction are made slightly wider is fixed to approximately the center of the plate surface 11a of the pendulum 11 via a spacer 16 and the other end 15b. Is similarly fixed to the frame body 12 on the side to which the pendulum 11 is connected via a spacer 17. The vibrator 15 is separated from the plate surface 11a of the pendulum 11 by a predetermined amount by the spacers 16 and 17, and is arranged substantially parallel to the plate surface 11a. A crystal oscillator, for example, is used as the oscillator 15, and is excited at a natural frequency by an excitation unit (not shown) when acceleration is detected.

Next, a method of detecting acceleration will be described. now,
For example, when acceleration α is applied to the frame body 12 supporting the pendulum 11 in a direction perpendicular to the plate surface 11a of the pendulum 11 as indicated by an arrow in FIG. 3B, the pendulum 11 moves in the direction opposite to the acceleration α. Receives an inertial force of a magnitude proportional to the acceleration α,
It rotates in the clockwise direction in FIG. This pendulum 11
Due to the rotation, the vibrator 15 whose one end 15a is fixed to the pendulum 11 receives a tensile force, and the natural frequency of the vibrator 15 increases. Therefore, by detecting the magnitude and direction of the change in the natural frequency by the frequency detection means (not shown),
The magnitude and direction of the input acceleration α is detected.

[0005]

By the way, the pendulum 11,
In order to form the assembly of the frame 12 and the hinge 13 in a small size and easily, and to obtain a good connection state between them, it is preferable to integrally form them with the same material as described above. A quartz plate is used because it has good spring characteristics and mechanical strength of No. 13, and excellent processing accuracy.

However, the coefficient of thermal expansion of quartz is 0.5.
Since ppm / ° C is considerably smaller than the thermal expansion coefficient of 13.7 ppm / ° C of the crystal used for the vibrator 15, when the environmental temperature changes, the difference between the thermal expansion coefficients causes the vibrator 15 and the pendulum 11 and Thermal stress is generated between the accelerometer and the frame body 12, which causes the vibrator 15 to break or peel off at the fixing portions of the vibrator 15 and the pendulum 11 and the frame body 12. There was a problem of breaking.

The object of the present invention is to solve the above mentioned problems,
It is an object of the present invention to provide a vibrating accelerometer in which thermal stress is hardly generated in the longitudinal direction of the vibrator even if the environmental temperature changes, and therefore the vibrator does not break due to the environmental temperature change.

[0008]

According to the present invention, there is provided a pendulum, a frame body arranged on the outer periphery of the pendulum, hinged to one end of the pendulum, and integrally formed with the same material as the pendulum, and one end of the pendulum. The vibrator is fixed and has the other end extended to the side of the frame to which the pendulum is connected, and a vibrator made of a material having a thermal expansion coefficient substantially equal to that of the vibrator. The support is fixed to both sides of the frame at positions corresponding to the ends of the vibrator.

Further, the vibrator is located between the frame and the support.

[0010]

In the present invention configured as described above, since the amount of expansion and contraction of the vibrator in the longitudinal direction due to the change in environmental temperature and the amount of expansion and contraction of the support in that direction are substantially equal, thermal stress is generated in the longitudinal direction of the vibrator. Rarely occurs.

[0011]

FIG. 1 shows an embodiment of the present invention. A hinge 23 in which a rectangular frame body 22 is arranged on the outer periphery in the plate surface direction of a rectangular plate-like pendulum 21 and one end of the pendulum 21 is elastically deformable.
It is connected to the frame body 22 via. The pendulum 21, the frame body 22, and the hinge 23 are integrally formed of the same material, and in this example, quartz is used as the material. That is, for example, a U-shaped hole 24 is formed in a thin quartz plate by laser cutting to form a frame body 22 and a section 25 supported by the U-shaped opening portion in the frame body 22 and chemically etched to form the section 25. By thinning the thickness of the section 25 near the support end in parallel with the support end, the hinge 23 that elastically deforms is formed. The free end side (opposite side to the support end) of the segment 25 divided by the hinge 23 serves as the pendulum 21, and the other support end side portion serves as an extension of the frame 22.

One end 15a of the substantially rectangular vibrator 15 in the longitudinal direction is fixed by adhesion through a spacer 26 in the shape of a rectangular parallelepiped to approximately the center of the plate surface 21a of the pendulum 21. Oscillator 1
A crystal oscillator is used for 5. The other end 15 of the oscillator 15
b is located on the side of the frame body 22 to which the pendulum 21 is connected, and is fixed to the support body 27 arranged between the vibrator 15 and the frame body 22 by adhesion.

The support 27 has a plate surface 27a having a shape in which a vertical portion of the T-shape is widened and a groove is formed in the vertical portion from the horizontal portion of the T-shape. Size,
That is, the thickness of the support body 27 is equal to the distance between the plate surface 21a of the pendulum 21 and the one end 15a of the vibrator 15, that is, the thickness of the spacer 26 at both ends of the T-shaped horizontal portion, and the other portions are spacers. It is smaller than the thickness of 26.

The support 27 has a tip 28 of the vertical portion of the T-shape.
a is located on the side of the frame 22 to which the pendulum 21 is connected and is fixedly adhered to the other end 15b of the vibrator 15, while the other end portions 28b and 28c having a large thickness have one end 15a of the vibrator 15.
The frame bodies 22 located on both sides of the pendulum 21 at positions corresponding to
Each is fixed by adhesion. Therefore, the support body 27 has the pendulum 21 and the frame body 2 except for the both end portions 28b and 28c.
2 is separated by a predetermined amount and is in a state of being substantially parallel and opposed.

The spacer 26, to which one end 15a of the vibrator 15 is fixed, is positioned in a groove 29 formed in the vertical portion of the T-shape of the support 27, and the vibrator 15 has a groove 29 of the groove 29. It is located almost on the center. As described above, it is arranged between the vibrator 15 and the frame body 22, the other end 15b of the vibrator 15 is fixed to one end, and the other end is the one end 15 of the vibrator 15.
The support bodies 27 fixed to both sides of the frame body 22 at positions corresponding to a are made of a material having a thermal expansion coefficient substantially equal to that of the vibrator 15. In this example, since a crystal oscillator (coefficient of thermal expansion = 13.7 ppm / ° C.) is used for the oscillator 15, the support 27 has, for example, a monel having a coefficient of thermal expansion of 13.7 ppm / ° C. and a value equal to that of crystal. Metal is used.

The vibration type accelerometer 3 constructed as described above.
The detection of the acceleration at 0 is performed in the same manner as the conventional vibration type accelerometer 10 shown in FIG. That is, when the acceleration α indicated by the arrow in FIG.
Receives an inertial force, the hinge 23 bends, and the pendulum 21 rotates around the hinge 23 in the clockwise direction in the drawing. The vibrator 15 excited by the exciting means (not shown) is the pendulum 2.
1, the tensile force is received, and the natural frequency of the vibrator 15 increases. Therefore, the magnitude and direction of the input acceleration α can be detected by detecting the magnitude and direction of the change in natural frequency with the frequency detection means (not shown).

Next, the influence of the change in environmental temperature on the vibration type accelerometer 30 will be described. As described above, the vibrator 15 and the support 27, which are made of materials having substantially the same coefficient of thermal expansion, have their ends 15a, 28b and 2 respectively.
8c and pendulum 21 and frame 2 integrally formed of the same material
2 and 2 are fixed at the same position in the longitudinal direction of the vibrator 15 and are further extended in the same direction to form the other end 1
5b and 28a are fixed to each other. Therefore, even if the environmental temperature changes, these end portions 15a and 28b, 28c
Is always located at the same position in the longitudinal direction of the vibrator 15, and the amount of expansion and contraction of the vibrator 15 in the longitudinal direction is substantially equal to the amount of expansion and contraction of the support 27 in that direction.
In the longitudinal direction of 5, the thermal stress hardly occurs between the vibrator 15 and the support 27 and between them and the pendulum 21 or the frame 22.

FIG. 2 shows another embodiment of the present invention, in which the vibrator 15 is located between the frame 22 and the support 27. That is, the spacer 26 disposed between the one end 15a of the vibrator 15 and the pendulum 21 has a small thickness, and the vibrator 15 is close to the pendulum 21 and the frame body 22 as shown in FIG. Parallel to each other. The other end 15b of the vibrator 15 is fixed to a mounting portion 28d integrally formed on the tip of the vertical portion of the T-shape on the plate surface 27b of the support 27 facing the frame body 22.

The protruding heights of both end portions 28b and 28c of the T-shaped horizontal portion from the plate surface 27b of the support 27 are set to be larger than the height of the upper surface 15c of the vibrator 15 with respect to the plate surface 21a of the pendulum 21. The opposing surfaces 15c and 27b of the vibrator 15 and the support body 27 are spaced from each other by a predetermined amount, and the mounting portion 28d is formed so as to project from the plate surface 27b at a height equal to this spacing amount. In this embodiment, the concave groove 29 formed in the portion of the support 27 facing the one end 15a of the vibrator 15 is a clearance for connecting the vibrator 15 with wiring from the excitation means and the frequency detection means. Is.

In the embodiment shown in FIG. 2, the vibrator 15 can be arranged closer to the hinge 23 as compared with the embodiment shown in FIG. 1, so that good detection sensitivity for input acceleration can be obtained. be able to. In each of the embodiments shown in FIGS. 1 and 2, one vibrator 15 is used as the detecting means, but the other plate surface 21b of the pendulum 21 is used.
Similarly, on the side, that is, the vibrator 15, the spacer 26, and the support 27 are arranged symmetrically with respect to the center plane parallel to the plate surface 21a of the pendulum 21, and two vibrators 15 are used. The output of the vibrator 15 may be taken out as a differential output. With this configuration, it is possible to improve the detection sensitivity, and it is possible to cancel the deviation of the natural frequency of the vibrator 15 due to, for example, a temperature change, so that it is not affected by the deviation.

[0021]

As described above, according to the present invention, the other end of the vibrator whose one end in the longitudinal direction is fixed to the pendulum is fixed to one end of the support made of a material having a thermal expansion coefficient substantially equal to that of the vibrator. Then, by fixing the other end of the support at a position corresponding to one end of the vibrator on both sides of a frame integrally formed on the outer periphery of the pendulum with the same material as the pendulum, vibrations will occur even if the environmental temperature changes. Almost no thermal stress is generated in the longitudinal direction of the child,
Therefore, it is possible to obtain a vibrating accelerometer in which the vibrator is not broken due to the change of the environmental temperature or the fixed portion thereof does not peel off.

In the conventional vibration type accelerometer 10 shown in FIG. 3, for example, a pendulum 11, a frame 12 and a hinge 1 are used.
If 3 can be integrally formed with the vibrator 15 by a material having a substantially equal thermal expansion coefficient, it is possible to prevent thermal stress from being generated between the vibrator 15 and the pendulum 11 and the frame 12 even if the environmental temperature changes. That is, the same effect as the effect of the present invention described above can be obtained. Examples of the material having a thermal expansion coefficient substantially equal to that of the crystal unit include Monel metal and Elgiloy which are exemplified as the material of the support in the embodiment of the present invention.

However, Monel metal has a poor spring property and cannot form a hinge which is elastically deformed well. Elgiloy has a good spring property, but its mechanical strength is insufficient and the hinge may be broken. However, there is a drawback that a thin plate causes warpage and a highly accurate shape and dimension cannot be obtained. Use of these materials greatly impairs the performance and reliability of the vibration accelerometer.

On the other hand, in the present invention, since the support is provided to eliminate the generation of thermal stress, the materials forming the pendulum, the frame and the hinge are formed without being restricted by the thermal expansion coefficient. It is possible to use the most suitable one, that is, there is an effect that each part of the vibration type accelerometer can be made of an optimum material.

[Brief description of drawings]

FIG. 1A is a perspective view showing an embodiment of a vibration type accelerometer according to the present invention, and FIG. 1B is a sectional view taken along line AA of FIG.

2A is a perspective view showing another embodiment of the vibration type accelerometer according to the present invention, and FIG. 2B is a sectional view taken along line AA of FIG.

FIG. 3A is a perspective view showing a conventional vibration type accelerometer.
(B) is AA sectional drawing of (A).

[Explanation of symbols]

 15 Transducer 21 Pendulum 22 Frame 23 Hinge 27 Support

Claims (2)

[Claims] 1. A pendulum, a frame body arranged on the outer periphery of the pendulum, hinged to one end of the pendulum, and integrally formed of the same material as the pendulum, and one end fixed to the pendulum, and the like. An oscillator whose end is extended to the side of the frame to which the pendulum is connected and made of a material having a thermal expansion coefficient substantially equal to that of the oscillator, and the other end of the oscillator is fixed to one end and the other end is A vibrating accelerometer, comprising: a support fixed to both sides of the frame at a position corresponding to the one end of the vibrator. 2. The vibratory accelerometer according to claim 1, wherein the vibrator is located between the frame and the support.