JPH05297017A - Acceleromator - Google Patents

Abstract

PURPOSE:To obtain an acceleromator which has a pendulum which is supported by a deflection joint and can constantly measure acceleration highly accurately by preventing an excessive amount of stress from being applied to a deflection part. CONSTITUTION:A first deflection part 20a which absorbs force in X-axis direction and further a second deflection part 20c which absorbs force in Y-axis direction are provided at a deflection joint 20. When an acceleration in Y-axis direction is operated on an accelerator, the first deflection part 20a does not deflect but only the second deflection part c deflects, thus preventing the first deflection part 20a from being subjected to an excessive amount of stress due to acceleration in Y-axis direction.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to accelerometers, and more particularly to servo accelerometers.

[0002]

2. Description of the Related Art FIGS. 4 and 5 show examples of conventional accelerometers. The accelerometer includes a cylindrical case 10, a first base or frame 12A mounted on the bottom surface 10a of the concave portion of the case 10, and a second base mounted on the first frame 12A so as to face each other. The base or frame 12B of the first,
A flexible joint 20 that is attached to the attachment portion 12a of the frame 12A of the frame 12A via a pressing plate 18 by a suitable fastener such as a screw, and a rod-shaped pendulum 30 attached to the other end of the flexible joint 20. A pair of cylindrical Toluca coils 34A, 34B mounted on the pendulum 30,
A pair of disk-shaped permanent magnets 36A, 36B and a pair of cylindrical pole pieces 3 which are spaced from the Toruca coils 34A, 34B and mounted on the frames 12A, 12B.
8A and 38B, a displacement detection device including a light emitting element 40A and a light receiving element 40B that are spaced apart from the tip end of the pendulum 30, and a pair of stoppers 42A and 42B disposed on the upper side thereof. ..

A reference surface 10c is provided on the flange portion 10b of the case 10, and a hole 10d is formed as shown in FIG.
Are formed. The accelerometer is mounted on the hull by mounting such reference surface 10c on the corresponding reference surface of the hull and inserting a suitable fastener, such as a screw, into hole 10d.

A cylindrical terminal case 44 is attached to the flange portion 10b of the case 10, and external terminals 50A and 50B are attached to the terminal case 44.

The cylindrical Toruca coils 34A and 34B are mounted on the pendulum 30 so that the central axes thereof are aligned with the central axis X-X of the accelerometer, and the cylindrical pole piece 38.
A and 38B are arranged inside.

The first frame 12A is disposed in the first frame 12A so that the end face 12b of the first frame 12A contacts the bottom surface 10a of the case 10, and is fixed by a suitable mounting means such as a screw 48 or the like. A lid 52 that also serves as a characteristic name plate is attached to the outside of the case 10, while the opening portion 44a formed in the terminal case 44 is closed by a lid 54.

In this way, the inside of the accelerometer has a closed structure. Therefore, after assembling the components inside the accelerometer, electrical connection is made through the opening 44a, and the inside is evacuated or inert gas is supplied. By filling and closing the opening 44a with the lid 54, the quality of the components can be maintained for a long time and the life of the accelerometer can be extended.

The pendulum 30, the Toluca coils 34A and 34B attached to the pendulum 30, and the flexible joint 20 are cantilevered by the mounting portion 12a of the first frame 12A, and the flexible joint 20 has an appropriate flexible portion 20a. Is formed, which allows the pendulum 30 to rotate about the axis of rotation O-O passing through such flexure 20a. For example, as shown in FIG. 5, the bending portion 20a may be formed by forming a rectangular hole 201 in the bending joint 20 and forming thin-walled portions on the two support columns on both sides thereof.

The first frame 12A is made of electromagnetic soft iron, and includes the first pole piece 38A to the first permanent magnet 36.
Functions as a yoke (return path) to form a magnetic circuit through A to the first frame 12A, and these cooperate with the first torquer coil 34A to provide the first torquer. The second frame 12B is made of electromagnetic soft iron and functions as a yoke (return path) to form a magnetic circuit from the second pole piece 38B to the second frame 12B via the second permanent magnet 36B. It cooperates with the second Toruca coil 34B to provide the second Toruca.

Here, as shown in the figure, the direction along the central axis of the pendulum 30 in the stationary state is the Z axis, and the direction along the central axis XX of the accelerometer, that is, a disk-shaped permanent magnet 36A. , 36B and cylindrical pole pieces 38A, 38
The direction passing through the center of B and perpendicular to the Z-axis is the X-axis, and the direction orthogonal to both the X-axis and the Z-axis is the Y-axis.

When acceleration acts along the central axis line XX of the accelerometer, the pendulum 30 rotates about the rotational axis line OO passing through the bending portion 20a, and its tip portion is slightly displaced. As a result, the amount of light emitted by the light emitting element 40A and received by the light receiving element 40B changes, and a minute displacement of the tip of the pendulum 30 is detected.

The signals indicating the minute displacements detected by the displacement detecting device are the torquer coils 34A and 34A.
The current is fed back to B and the current flowing through the torquer coils 34A and 34B is controlled so that the minute displacement becomes zero.
Since such a current, that is, the constraint current is proportional to the input acceleration, the input acceleration can be measured by measuring the constraint current.

Stoppers 42A and 42B, which are spaced from the pendulum 30 and arranged on both sides thereof, function to limit the range of movement of the tip of the pendulum 30 in the direction of the axis XX, thereby supporting the pendulum 30. Flexible joint 20
It is possible to prevent excessive stress from being generated.

[0014]

In such a conventional accelerometer, when used in an environment where there is a large impact or vibration, a large stress is generated in the bending portion 20a of the bending joint 20 and the accelerometer Occasionally the function was impaired.

When acceleration is applied to the accelerometer in the X-axis direction, that is, in the acceleration detection direction, the movement range of the tip portion of the pendulum 30 in the axis XX direction is restricted by the stoppers 42A and 42B, and the tip portion of the pendulum 30 is restricted. When is greatly displaced and comes into contact with the stoppers 42A and 42B, the force acting on the center of gravity of the pendulum 30 is carried by the stoppers 42A and 42B.
Excessive stress does not act on the bending portion 20a.

When acceleration is applied to the accelerometer in the Z-axis direction, uniform axial stress acts on the two columns forming the flexure portion 20a of the flexure joint 20, and it is possible to withstand a considerably large external force.

However, when a large acceleration in the Y-axis direction is applied to the accelerometer, the two columns forming the bending portion 20a of the bending joint 20 are not subjected to uniform stress. As shown in FIG. 5, when a force F in the Y-axis direction is applied to the center of gravity G of the pendulum 30, bending stress is generated in the bending joint 20 and the bending portion 20.
A compressive stress is generated in one of the two columns of a and a tensile stress is generated in the other.

The center distance between the two columns of the flexible portion 20a is L
_1, and when the distance between the rotational axis O-O and the center of gravity G of the pendulum 30 and L _2, the size of such stresses the ratio L ₂ / L ₁
Proportional to the size of.

Therefore, when the value of the ratio L ₂ / L ₁ is large, excessive stress acts on the two columns of the bending portion 20a, which deteriorates the performance of the accelerometer.

In view of this point, the present invention is directed to the flexible portion 20a.
In an accelerometer having a pendulum 30 supported by a flexure joint 20 in which is formed, an accelerometer capable of preventing an excessive stress from acting on the flexure 20a and always measuring acceleration with high accuracy. The purpose is to provide.

[0021]

According to the present invention, as shown in FIG. 1, for example, a base 12A and a base 1 having a first end portion are provided.
2A of the flexible joint 20 and the second of the flexible joint 20
Between the pendulum 30 attached to the end of the pedestal, the torquers 34A, 34B that generate torque proportional to the acceleration input to the pendulum 30 from the base via the flexible joint 20, and between the base and the pendulum 30. In the accelerometer having the displacement detection devices 40A and 40B for detecting the relative displacement of the flexible joint 20, the flexible joint 20 is formed with the first flexible portion 20a for displacing the pendulum 30 in the acceleration detection direction. An opening 202 is formed at the second end of the joint to form a frame-shaped annular portion, and the pendulum 30 is displaced in a direction perpendicular to the acceleration detection direction by two columnar portions on both sides of the frame-shaped annular portion. The second flexible portion 20c for forming the pendulum 30 is attached to the beam portion connecting the two columnar portions, and the torquer 3
4A, 34B at the corresponding positions on both sides of the Toruca 34A,
Stoppers 60A and 60B that are spaced apart from 34B and limit the movement of the pendulum 30 are mounted.

According to the accelerometer of the present invention, for example, as shown in FIG. 1, the center of gravity of the pendulum 30 is arranged at the center position in the longitudinal direction of the two columnar parts forming the second flexible part 20c.

According to the accelerometer of the present invention, the flexible joint 20
The second flexible portion 20c is formed by wire-cut electric discharge machining of one plate material.

[0024]

In addition to the first bending portion 20a that absorbs the force in the X-axis direction, the bending joint 20 is further provided with the second bending portion 20c that absorbs the force in the Y-axis direction. When acceleration in the Y-axis direction acts on the meter, the first bending portion 20a
Does not bend and only the second bending portion 20c bends. Therefore, the first bending portion 20a is prevented from being excessively stressed by the acceleration in the Y-axis direction.

The pendulum 30 has stoppers 60A and 60B.
Is provided, which limits the displacement of the pendulum 30 and prevents the second flexure 20c from being subjected to excessive stress.

[0026]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3, the same parts as those in FIGS. 4 to 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a main part of an example of the accelerometer of the present invention. Only a pendulum 30, a flexible joint 20 for supporting the pendulum 30 in a cantilever manner, and torquer coils 34A, 34B mounted on the pendulum 30 are shown. It is shown.

As shown in FIG. 2, the Toruca coil 34A,
Openings 34e and 34d are provided at the lower end of 34B, respectively, and the flexible joint 20 has such openings 34e and 34d.
34d through and in non-contact with them,
In this way, the pendulum 30 and the Toruca coils 34A and 34B attached to the pendulum 30 can be displaced by bending the flexible joint 20.

According to this example, the flexible joint 20 includes a lower fixing portion 20b for attaching to the first frame 12A and a first bending portion 2 formed on the upper side of the fixing portion 20b.
0a, a second bending portion 20c arranged on the upper side of the first bending portion 20a, and a mounting portion 20d arranged on the upper end portion for mounting the pendulum 30.

The fixing portion 20b is provided with holes 20e and 20e, and by pressing a screw into the holes 20e and 20e, the pressing plate 1 as shown in FIGS. 4 and 5.
The flexible joint 20 is attached to the first frame 12 </ b> A via 8. It should be noted that as the means for attaching the flexible joint 20 to the first frame 12A, other known means such as adhesion or welding may be used.

The first flexure 20a may be of a form such as that formed on the flexure joint 20 of the conventional accelerometer shown in FIGS. 4 and 5, and may have a suitable first shape such as a rectangular first opening 201. The thin portion may be formed on the two columns provided on both sides thereof.

The second bending portion 20c is the first bending portion 20a.
It may be constituted by a member having a width smaller than that of the portion (2), and the second opening portion 202 having an appropriate shape, for example, a rectangular shape may be provided so that two columns are formed on both sides thereof. The two struts may have, for example, a rectangular or square cross section, and may have suitable thin sections, not shown.

The rigidity of the second bending portion 20c will be described below with reference to FIG. 3, but is smaller than that of the first bending portion 20a with respect to the deformation in the Y-axis direction, that is, the accelerometer has a Y value. When the acceleration in the axial direction acts, the first bending portion 20a moves to Y
Only the second bending portion 20c is configured to bend in the Y-axis direction without bending in the axial direction.

The second opening 202 is preferably arranged at the central position of the Toruca coils 34A, 34B, and more preferably so that the central positions of the two are aligned. Therefore, the center position of the second opening 202 is X, Y,
It is arranged at the intersection O of the three axes of the Z axis.

The mounting portion 20d is composed of a beam portion that connects two columns on the upper side of the second opening 202. As shown in the drawing, the center of the beam portion is removed to provide a gap. It may be configured to mount the pendulum 30. Preferably, the two protrusions 20f, 20 formed by the gap
The end portion of the pendulum 30 is sandwiched between f so that the end surface of the pendulum 30 is flush with the upper inner surface of the second opening 202.

Thus, the portion above the rotation axis O-O passing through the first bending portion 20a, that is, the portion above the rotation axis O-O within the first bending portion 20a, the pendulum 30, and the torquer coils 34A, 34B. And form a pendulum part.

The center of gravity G of the pendulum portion is preferably
It is arranged at the center position of the second opening 202 of the second flexible portion 20c. In this way, the center of gravity G of the pendulum portion is arranged at the intersection 0 of the three axes when stationary.

When acceleration acts on the accelerometer, a force proportional thereto acts on the center of gravity G of the pendulum portion. Second flexure 2
0c is deformed by this, but since the point of action of the force is at the center G of the second flexible portion 20c, the portion of the tip from the second flexible portion 20c is in a state where its axis is arranged parallel to the Z axis. Displace. Therefore, the resonance point can be set high even if the second bending portion 20c is provided, and the buckling stress in the second bending portion 20c can be zero with respect to the acceleration in the Y-axis direction.

A pair of second stoppers 60 are arranged along the Y-axis on both sides of the torquer coils 34A and 34B as shown in the figure.
A and 60B are arranged and such stoppers 60A and 60B are provided.
This limits the displacement range of the Toruca coils 34A and 34B in the Y-axis direction. Appropriate gaps δ ₁ , δ ₂ are formed between the stoppers 60A, 60B and the outer peripheral surfaces B ₁ , B ₂ of the torquer coils 34A, 34B.

Next, referring to FIG. 3, the operation of the accelerometer of this example will be described.
Explain the work. Acceleration α in the Y-axis direction with respect to the accelerometer_Y
Is applied, the first bending portion 20a does not deform and
Only the second bending portion 20c is deformed. As mentioned above, shake
The center of gravity of the child is located at the center of the second opening 202.
By placing the pendulum unit, ₁
-Z₁Is displaced in a state parallel to the Z axis.

Therefore, the two columns of the second flexible portion 20c are deformed into an S shape as shown in the figure. FIG. 3 thus shows the pendulum portion, that is, the upper portion of the second bending portion 20c and the pendulum 30.
And the Toruca coils 34A and 34B are displaced in the Y-axis direction,
The state where the axis line Z ₁ -Z _{1 of the} pendulum 30 is displaced by δ _{Y in the} Y-axis direction is shown.

The gaps δ ₁ and δ ₂ are set to values smaller than the maximum displacement amount δ _{YMAX in} the Y axis direction of the torquer coils 34A and 34B corresponding to the maximum acceleration α _YMAX acting on the accelerometer. The gaps δ ₁ and δ ₂ are defined by the pendulum 3
0 or the Toluca coils 34A and 34B are displaced by the maximum displacement amount δ _{YMAX in the} Y-axis direction, the second flexible portion 20c.
Is set so that the stress generated in the two columns is less than the allowable stress.

When acceleration in the Y-axis direction acts on the accelerometer, the first bending portion 20a formed on the bending joint 20 hardly bends, and only the second bending portion 20c bends. The acceleration of is absorbed by only the second bending portion 20c. Moreover, the displacement amount of the second bending portion 20c is
Since it is limited by the second stoppers 60A and 60B, the stress exceeding the allowable stress does not act on the second flexible portion 20c.

The flexure joint 20 is preferably manufactured from a thin sheet of material, which may be formed in any suitable manner, for example by wire cut electrical discharge machining.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned embodiments, and it will be understood by those skilled in the art that various other configurations can be adopted without departing from the gist of the present invention. Easy to understand.

[0046]

According to the accelerometer of the present invention, the flexible joint 20
Since a second bending portion 20c that absorbs an external force in the Y-axis direction is provided in addition to the first bending portion 20a that absorbs the external force in the X-axis direction, the acceleration in the Y-axis direction acts on the accelerometer. However, excessive stress does not act on the first bending portion 20a, and therefore, there is an advantage that the first bending portion 20a can be protected from excessive stress.

In the accelerometer of the present invention, the Toruca coil 34 is used.
Since the second stoppers 60A and 60B that limit the displacement are arranged on both sides of the A and 34B, the second bending portion 20c that absorbs the external force in the Y-axis direction is prevented from being excessively deformed, Therefore, there is an advantage that the second bending portion 20c can be protected from excessive stress.

In the accelerometer of the present invention, the center of gravity G of the pendulum portion is
Is disposed at the center position of the second opening 202 of the second bending portion 20c, the resonance point can be set high even if the second bending portion 20c is provided on the bending joint 20, and There is an advantage that the buckling stress in the second bending portion 20c can be made zero with respect to the acceleration in the Y-axis direction.

According to the present invention, even if the flexible joint 20 is provided with the second flexible portion 20c, the flexible joint 20 can be easily formed by forming the flexible joint 20 from a single plate material and manufacturing it by, for example, wire-cut electric discharge machining. Since it can be manufactured, it is not necessary to increase the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of an example of an accelerometer of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is an explanatory diagram showing the operation of the accelerometer of the present invention.

FIG. 4 is a front view showing an example of a conventional accelerometer.

FIG. 5 is a plan view showing an example of a conventional accelerometer.

[Explanation of symbols]

 10 Case 10a Bottom face 10b Flange part 10c Reference surface 12A, 12B Frame 12a Attachment part 18 Holding plate 20 Flexible joint 20a First flexible part 20b Fixed part 20c Second flexible part 20d Mounting part 20e Hole 20f Projection part 30 Pendulum 34A, 34B Toruca coil 34e, 34d Hole 36A, 36B Permanent magnet 38A, 38B Pole piece 40A Light emitting element 40B Light receiving element 42A, 42B Stopper 44 Terminal case 44a Opening 48 Screw 50A, 50B External terminal 52, 54 Lid 60A, 60B Stopper 201, 202 Aperture

Claims (3)

[Claims] 1. A base, a flexible joint having a first end attached to the base, a pendulum attached to a second end of the flexible joint, and a flexible joint from the base. A torquer that generates a torque proportional to the acceleration input to the pendulum via a flexible joint, and an accelerometer having a displacement detection device that detects relative displacement between the base and the pendulum, A first flexible portion for displacing the pendulum in the acceleration detection direction is formed on the flexible joint, and an opening is formed at a second end of the flexible joint to form a frame-shaped annular portion. A second flexible portion for displacing the pendulum in a direction perpendicular to the acceleration detection direction is formed by the two columnar portions on both sides of the frame-shaped annular portion, and the two columnar portions are connected to each other. The above pendulum is attached to the beam part that Accelerometer, characterized in that the stopper for limiting the movement of the pendulum is mounted spaced from the torquer at that position. 2. The accelerometer according to claim 1, wherein the second
The center of gravity of the pendulum is arranged at the center position in the longitudinal direction of the two columnar portions that form the flexible portion of the accelerometer. 3. The accelerometer according to claim 1, wherein the second flexible portion of the flexible joint is formed by wire-cut electric discharge machining of one plate material.