JP3429054B2 - Pendulum acceleration sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pendulum type acceleration sensor in which a pendulum is braked by an eddy current brake, and more particularly to a pendulum shaft support structure.

[0002]

2. Description of the Related Art Conventionally, as a sensor for detecting acceleration (inclination angle), there is a sensor constituted by an inclination angle detector such as a pendulum type or a leaf spring type. All of them convert the amount of displacement such as pendulum vibration due to acceleration or gravity, bending of a leaf spring, etc. into an electric signal by means of optical sensor, magnetic sensor, or change in capacitance, and based on this electric signal, the acceleration of the measured object. (Tilt angle) is detected. These acceleration (inclination angle) detectors are equipped with a damper mechanism for the purpose of preventing resonance (fluttering) of movable bodies such as pendulums and leaf springs due to external vibrations, and for providing appropriate response characteristics. There is.

As the damper mechanism, for example, there is one using a liquid such as silicone oil or antifreeze. When the damper mechanism is configured by using the liquid as described above, there is a problem that the closed structure is costly. Furthermore, the damping characteristic changes due to the change in the viscosity of the liquid due to the temperature change. That is, the damper mechanism using the liquid has an unavoidable problem that the response characteristics change due to the temperature change. Therefore, in order to eliminate these drawbacks of the damper mechanism using liquid, a damper mechanism utilizing magnetism has been adopted. This magnetic damper mechanism has a structure in which permanent magnets are arranged to face each other with a pendulum made of a non-magnetic conductive material sandwiched therebetween, and is configured to brake the pendulum by an eddy current generated as the pendulum swings. Since this magnetic damper mechanism is not affected by temperature changes, it has excellent temperature characteristics.
An acceleration sensor equipped with this conventional magnetic damper mechanism is shown in FIG.
8 through 8.

FIG. 6 is a perspective view showing a schematic structure of a conventional pendulum type acceleration sensor, FIG. 7 is a plan view thereof, FIG. 8A is a sectional view thereof, and FIG. 8B is a sectional view taken along line VIIIb-VIIIb of FIG. FIG. 6C is a sectional view taken along line VIIIc-VIIIc of FIG. In these drawings, a pendulum type acceleration sensor indicated by reference numeral 10 as a whole has a structure in which a pendulum 11 as an oscillating body oscillates around a support shaft 12. The pendulum 11 is formed of a non-magnetic conductive material in a fan shape, and has a plurality of slits 11a and holes 11b formed in the outer peripheral portion.
6 and 7, the support base of the acceleration sensor 10 for swingably supporting the pendulum 11 and the pendulum 11 are shown.
The detecting means and the like for detecting the amount of displacement and converting it into an electric signal are omitted.

Reference numeral 13 denotes a magnetic damper, which has a yoke 14 having a U-shaped cross section and a permanent magnet 1 fixed to the yoke 14.
And a yoke 14 and a permanent magnet 15
1 are arranged so as to face each other. The yoke 14 is fixed to the support 16 so that the magnetic pole portions 14a at both ends face the pendulum 11 side, and the permanent magnet 15 is attached to the central portion of the yoke 14 in the width direction. That is, the magnetic pole surface 14b at the tip of the magnetic pole portion 14a faces the side surface of the pendulum 11. The permanent magnet 15 is magnetized in a direction parallel to the axial direction of the pendulum 11. Further, the installation position of the yoke 14 is set such that the permanent magnet 15 is positioned directly below the support shaft 12 and faces the outer peripheral portion of the pendulum 11.

A printed circuit board 17 has a rectangular hole 17a.
Is pierced and is positioned and attached to the support base 16. On the printed board 17, a light receiving / light emitting element which is a detecting means for detecting the displacement amount of the pendulum 11 and converting it into an electric signal is housed. Two pairs of holders 18 are attached so as to sandwich the pendulum 11. The support 16 includes:
A pair of opposed shaft supporting portions 16a is erected upright through the hole 17a, and the support shaft 12 has the shaft supporting portions 16a.
In addition, the pendulum 11 is supported so as to be swingable.

Next, the operation of the conventional pendulum type acceleration sensor configured as described above will be described. When an external acceleration is applied to the pendulum 11 or the support base 16 is tilted, the pendulum 11 swings around the support shaft 12. Then, the pendulum 11 crosses the magnetic flux between the opposing permanent magnets 15 and between the yokes 14. This magnetic flux is shown by an arrow Φ in FIG. 7. As the pendulum 11 traverses the magnetic flux in this manner, an eddy current is generated in the pendulum 11, and the pendulum 11 is braked as an eddy current brake. When the pendulum 11 is braked, tilted and stopped,
The optical path of the light receiving / light emitting element, which was housed in the holder 18 and opened through the slit 11a and the hole 11b, was blocked, and the displacement amount of the pendulum 11 was detected by the change in the amount of light received by the light receiving element and converted into an electric signal. Acceleration is detected.

[0008]

In the conventional accelerometer described above, the shaft support portion 16a for supporting the pendulum 11 is supported.
Since the holder 18 for accommodating the light receiving / light emitting element which is the displacement amount detecting means is formed as a separate body,
Due to the stacking of manufacturing errors and assembly errors, the alignment accuracy of the light-receiving / light-emitting elements with respect to the pendulum 11 deteriorates, and thus the detection accuracy decreases. Further, the yokes 14 arranged so as to sandwich the pendulum 11 are located on the outside of each of the shaft support portions 16a structurally, and thus the shaft support portions 16a are separated in thickness. As described above, in the conventional accelerometer, the shaft support portion 16a has the holder 1
Since it is formed as a separate body from 8 and is integrally formed so as to be opposed to the support base 16 so as to be opposed to each other, there is a limit in reducing the wall thickness of the shaft support portion 16a in terms of strength. The distance between the permanent magnets 15 becomes large, and therefore, in order to obtain a predetermined magnetic flux density Φ, the permanent magnets 15 must be made large, and a pair of them must be provided, and the device itself becomes large and parts There is a drawback that the points increase and the cost becomes high.

Therefore, the present invention has been made in view of the above-mentioned problems or drawbacks of the related art, and an object thereof is to improve detection accuracy, and to make the pendulum type acceleration sensor compact and inexpensive. To provide.

[0010]

In order to achieve this object, a pendulum type acceleration sensor according to the present invention detects a pendulum swinging in response to an acceleration and a displacement amount of the pendulum to detect the acceleration. Displacement amount detecting means is provided, a shaft supporting portion for swingably supporting the pendulum is integrated with a holder for accommodating the displacement amount detecting means, the pendulum is formed of a non-magnetic conductor, and the pendulum swings. A pendulum type acceleration sensor in which a yoke for generating a magnetic flux in a direction orthogonal to the movement and a permanent magnet are provided, and a holder for supporting the holder and the holder are separated. Further, in the pendulum type acceleration sensor according to the present invention, the shaft support portion of the holder is extended downward to form a mounting portion between the yoke and the permanent magnet, and the yoke and the permanent magnet are disposed below the mounting portion of the holder. A fitting insertion hole for inserting and is provided.

[0011]

According to the present invention, the holder for supporting the holder and the holder are separated, so that the yoke and the permanent magnet can be freely arranged in the separated space.
The yoke and permanent magnet can be placed close to the pendulum. Further, according to the present invention, since the yoke and the permanent magnet are fixed to the holder side where the shaft supporting portion is formed, the base is not required.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a pendulum type acceleration sensor according to the present invention, FIG. 2 (a) is a cross-sectional view of a main part, (b) is II of (a).
It is a sectional view taken along line b-IIb. In these figures, a pendulum type acceleration sensor indicated by reference numeral 1 is generally composed of a support base 2, a magnetic damper 3, a printed circuit board 4, a holder 5 for accommodating displacement amount detecting means, and a pendulum 7. The support base 2 is formed in a substantially flat plate shape, and the dowel 2a is provided at the center of the bottom surface.
However, a pair of pins 2b and a screw mounting boss 2c are respectively provided on the end edges of the bottom surface so as to project.

The magnetic damper 3 is a yoke 3a having a U-shaped cross section.
And one permanent magnet 3b attached to one side surface of the yoke 3a, and a hole 3c is formed in the bottom surface of the yoke 3a. A rectangular hole 4a is formed substantially in the center of the printed circuit board 4, and a pair of holes 4b are formed at both ends of the hole 4a.
And 4 pairs of holes 4c are formed, and a pair of holes 4d and a pair of holes 4e are formed on the edge. The holder 5 is provided with a shaft support portion 5b provided in a slit shape at the center of the upper end thereof and a pair of support walls 5a having wedge-shaped protrusions 5c protruding from both side surfaces thereof, which are opposed to each other. , Two pairs of storage concave fitting portions 5e and 5f are provided so as to face each other. The lower ends of the pair of support walls 5a are extended downward, and the extended portion 5g is provided with a recess 5h into which the permanent magnet 3b and the yoke 3a are fitted. The extended portion 5g of this portion is thin-walled. Is formed in. In addition, a rectangular fitting insertion hole 5i is formed on the bottom surface of the holder 5.

Reference numerals 6a and 6b denote light emitting elements,
Two pairs of light receiving elements are provided, respectively (a pair is not shown), and the storage recessed fitting portions 5e and 5f sandwich the gap 5d formed between the support walls 5a and store them so as to face each other. Has been done. The pendulum 7 is made of a non-magnetic conductor and has a substantially fan shape.
A and a hole 7b are bored, and a support shaft 7c is fixed to the center of the upper portion in a perpendicular manner. Reference numeral 8 denotes a cover, and four elastic engagement pieces 8a are provided at the four corners of the bottom surface so as to project downward. Reference numeral 9 is a panel to which the acceleration sensor 1 is attached.

Next, a method of assembling the pendulum type acceleration sensor 1 having such a structure will be described. First, the dowel 2 of the support base 2
The hole 3c of the yoke 3a is fitted and fixed to a, and the magnetic damper 3 is erected on the bottom surface of the support base 2. Next, the light-emitting element 6a and the light-receiving element 6b are housed in the housing recessed fitting portions 5e and 5f of the holder 5, and the dowel (not shown) projecting from the lower surface of the holder 5 is fitted into the hole 4b. 5 is attached to the printed circuit board 4. Then, the hole 4d of the printed circuit board 4 is fitted into the pin 2b, a screw (not shown) is inserted into the hole 4e, and the dowel 2c is screwed into the support base 2 to attach the light emitting element 6a and the light receiving element 6b. The legs 6c are inserted into the holes 4c and soldered. At this time, the magnetic damper 3 is exposed to the upper part of the printed circuit board 4 through the hole 4a, and the yoke 3a and the permanent magnet 3b of the magnetic damper 3 are fitted into the recess 5h of the shaft support 5a.

The support shaft 7c of the pendulum 7 is attached to the shaft support 5
Inserted in b, the pendulum 7 is swingably supported within the gap 5d around the shaft support portion 5b. At this time, the yoke 3a and the permanent magnet 3b are located on the side surface of the pendulum 7, and the slit 7a and the hole 7b are located so as to face the light emitting element 6a and the light receiving element 6b. Finally, the elastic engagement piece 8a of the cover 8 is engaged with the protrusion 5c to mount the cover 8 so as to cover the support wall 5a.
To prevent it from coming off.

In the pendulum type acceleration sensor 1 assembled in this way, the holder 5 is integrally formed with the shaft support portion 5b for supporting the support shaft 7c of the pendulum 7, so that the shaft support portion 5b and the accommodation recess fit. Assembling error and manufacturing error do not occur between the parts 5e and 5f, and the positional relationship between the slit 7a and the hole 7b of the pendulum 7 and the light emitting element 6a and the light receiving element 6b is always kept constant. The detection accuracy is improved. Further, since the holder 5 has a structure separated from the base 2, the yoke 3a and the permanent magnet 3b of the damper 3 can be inserted into the spaces formed on both sides of the pendulum 7 through the insertion holes 5i, The yoke 3a and the permanent magnet 3b are formed in the recess 5
It can be fitted into h.

Extension portion 5g of the portion where the recess 5h is formed
Is a portion that is irrelevant to the strength of the holder 5, and can be formed in a thin shape. Therefore, the yoke 3a and the permanent magnet 3b can be arranged close to the pendulum 7, so The permanent magnet 3b is used to obtain the magnetic flux density Φ.
It suffices to dispose only one, and the number of parts can be reduced and the size can be reduced. Also,
Since the yoke 3a is fixed to the boss portion 2a of the base 2, the yoke 3a is divided into two parts as in the conventional case.
Assembling becomes easy without having to install it on each side of the holder.

3 to 5 show a second embodiment of the present invention, FIG. 3 is an exploded perspective view of the whole, FIG. 4 is a sectional view, and FIG. 5 is a sectional view taken along line VV in FIG. In the second embodiment, the acceleration sensor 1 is directly attached to the panel or the like without using the base 2 which is required to attach the panel 9 or the like in the first embodiment. That is, in this embodiment, the gap between the yoke 3a of the damper 3 and the permanent magnet 3b is set to be slightly smaller than the gap between the recesses 5h formed in the extended portion 5g of the holder 5, and the elastic deformation of the yoke 3a is used. The damper 3 is fixed to the holder 5 so that both the concave portions 5h are sandwiched between the yoke 3a and the permanent magnet 3b.

A pair of holes 4f are formed on both sides of the hole 4a of the printed circuit board 4, and a hole 4g is formed on the back side thereof. A pair of mounting portions 5j having holes corresponding to the holes 4f are provided on both sides of the holder 5, and a mounting portion 5k having blind holes corresponding to the holes 4g is provided on the rear surface.
Are formed so as to project. Panel 9 has holes 4
A hole 9a, which is slightly larger than the hole 4a, is formed corresponding to a, and a pair of holes 9b corresponding to the hole 4f are formed on both sides of the hole 9a.

In such a structure, the holder 5, on which the damper 3, the light emitting / receiving elements 6a and 6b and the pendulum 7 are mounted, has the hole 4g and the pin 4h fitted and fixed in the blind hole of the mounting portion 5k. The printed circuit board 4 is attached and the whole is configured as a unit of the acceleration sensor 1. The acceleration sensor 1 unitized in this way is
Pin 9 fitted and fixed in holes 4f and 9b of mounting portion 5i
It is attached to the panel 9 by c. The yoke 3a and the pin 4h of the acceleration sensor 1 attached to the panel 9 are
It is located in the hole 9 a of the panel 9.

As described above, according to this embodiment, since the base 2 is not required, the number of parts can be reduced, the cost can be reduced, and the size can be reduced. Further, since the yoke 3a and the permanent magnet 3b are attached to the recess 5h of the extending portion 5g, the permanent magnet 3b and the pendulum 7 and the distance between the pendulum 7 and the yoke 3a are always kept constant, and the pendulum 7 is fixed. The magnetic flux density across it becomes constant, and a stable damper function is obtained.

In this embodiment, the cover 8 serves to support the support shaft 7.
Although c is prevented from coming off from the shaft support portion 5b, the cover 8 is not necessary if the groove into which the support shaft 7c of the shaft support portion 5b is inserted is formed into an undercut shape and a constricted portion is formed in the groove. Becomes In addition, in this embodiment, the acceleration sensor 1 is mounted on the panel 9
Although the pin 9c is used for attaching to, the present invention is not limited to this, and it goes without saying that various fixing means may be used for fixing with an adhesive.

[0024]

[0025]

As described above, according to the present invention, since the holder for supporting the holder and the holder are separated, the yoke and the permanent magnet can be fitted and arranged in the spaces on both sides of the pendulum, and the yoke and the permanent magnet can be arranged. Can be arranged close to the pendulum, and therefore, the number of permanent magnets can be reduced to one, the number of parts can be reduced, and the size can be reduced.

Further, according to the present invention, the shaft supporting portion of the holder is extended downward to form a mounting portion between the yoke and the permanent magnet, and the yoke and the permanent magnet are fitted and inserted below the mounting portion of the holder. Since the fitting insertion hole is provided and the base is unnecessary, the size is small and the cost is low. Further, since the yoke and the permanent magnet are attached to the extended portion, the distance between the permanent magnet and the pendulum and the distance between the pendulum and the yoke are always kept constant, the magnetic flux density across the pendulum becomes constant, and a stable damper function is provided. Is obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a pendulum type acceleration sensor according to the present invention.

FIG. 2 shows a pendulum type acceleration sensor according to the present invention,
(A) is sectional drawing, (b) is the IIb-IIb sectional view taken on the line in (a).

FIG. 3 is an exploded perspective view of a second embodiment of a pendulum type acceleration sensor according to the present invention.

FIG. 4 is a sectional view of a second embodiment of the pendulum type acceleration sensor according to the present invention.

5 is a sectional view taken along line VV in FIG.

FIG. 6 is a perspective view showing a schematic configuration of a conventional pendulum acceleration sensor.

FIG. 7 is a plan view showing a schematic configuration of a conventional pendulum type acceleration sensor.

FIG. 8 shows a conventional pendulum acceleration sensor, (a)
Is a sectional view, (b) is a sectional view taken along line VIIIb-VIIIb in (a), and (c) is a sectional view taken along line VIIIc-VIIIc in (a).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pendulum type acceleration sensor, 2 ... Support stand, 3 ... Magnetic damper, 4 ... Printed circuit board 4h ... Pin, 5 ... Holder, 6a ... Light emitting element, 6b ... Light receiving element, 7 ... Pendulum, 9 ... Panel, 9c ... Pin .

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-126562 (JP, A) JP-A-5-126845 (JP, A) JP-A-5-188078 (JP, A) JP-A-3- 146816 (JP, A) Actual development 4-116769 (JP, U) Actual development 5-11016 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01P 15/093 G01C 9 / 00 G01C 9/12

Claims (2)

(57) [Claims] A pendulum which swings 1. A depending on the acceleration, the displacement amount detecting means for detecting acceleration by detecting the amount of displacement of the pendulum is provided et al is said to holder for accommodating a pre-Symbol displacement detecting means A shaft support portion that swingably supports the pendulum is integrated, and the pendulum is formed of a non-magnetic conductor.
A pendulum type acceleration sensor provided with a yoke and a permanent magnet that generate a magnetic flux in a direction orthogonal to the swing of the pendulum.
The holder that supports the holder and the holder.
Pendulum type acceleration sensor characterized by being separated . 2. A pendulum that swings in response to acceleration, and
Displacement amount detection that detects the amount of displacement of the pendulum to detect acceleration
Means for storing the displacement amount detecting means.
The shaft support part that swingably supports the pendulum is integrated with the dar.
And forming the pendulum with a non-magnetic conductor,
A yaw that generates a magnetic flux in a direction orthogonal to the swing of this pendulum
In a pendulum type acceleration sensor that has a magnet and a permanent magnet.
The shaft support portion of the holder extending downward and
The holder for the magnet and the permanent magnet.
The yoke and the permanent magnet under the mounting portion of the
Pendulum type acceleration sensor characterized by having a fitting insertion hole
Nsa.