JP3165836B2 - Servo accelerometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pendulum having a coil interlinking with a magnetic flux formed by a permanent magnet and a magnetic housing. The present invention relates to a servo accelerometer configured to be balanced.

[0002]

2. Description of the Related Art An example of a conventional servo accelerometer of this type is shown in FIG. Pendulum 1 located in the frame of circular frame 11
2 has a substantially disk shape with a part of its circumference cut out by chords, and the cutout portion is connected to the frame 11 via a pair of hinges 13 and supported by the frame 11. Frame 11, pendulum 12
The hinge 13 and the hinge 13 are integrally formed, and quartz is used for the material. Note that the hinge 13 is made thin so as to allow the required swing of the pendulum 12.

A first housing 14 is provided on both plate surfaces of the frame 11.
And the second housing 15 are in contact with each other, and the frame 11 is held between the first and second housings 14 and 15. Each of the first and second housings 14 and 15 has a substantially cylindrical shape in which one end is open and the other end is covered, and one end of the first and second housings 14 and 15 is in contact with the frame 11. First and second housing 1
Reference numerals 4 and 15 also serve as a magnetic yoke, and are made of a magnetic material. As the material, an invar material having magnetism and a small thermal expansion coefficient is used.

At the center of the first and second housings 14 and 15, columnar first and second permanent magnets 16 and 17 made of, for example, a samarium-based rare earth cobalt magnet are mounted. In this example, the first and second permanent magnets 1
6, 17 are disk-shaped bottom pole pieces 18,
19, the bottom 1 of the first and second housings 14, 15
4a and 15a are coaxially erected and disk-shaped pole pieces 21 and 22 having thicker peripheral portions are disposed on the upper surfaces of the first and second permanent magnets 16 and 17, respectively. Is done.

The first and second permanent magnets 16, 17 and the bottom pole pieces 18, 19 and the pole pieces 21, 22 are assembled by, for example, bonding. Bottom pole piece 1
8, 19 and pole pieces 21 and 22 are made of an electromagnetic soft iron material (J
IS C 2503), and the bottom pole pieces 18 and 19 are formed by the first and second housings 14 and 1.
5 are attached and fixed to the bottoms 14a and 15a by bonding or laser welding, respectively. Note that the bottom pole pieces 18 and 19 are connected to the first and second housings 14 and 1.
5 has a function of reducing the difference in thermal expansion between the first and second permanent magnets 16 and 17.

The first permanent magnet 16 is, for example, a pole piece 2
1 is an N-pole, and a side that is in contact with the bottom pole piece 18 is an S-pole. These and the first housing 14 form a magnetic circuit, and the inner peripheral surface of the opening of the first housing 14 and the first permanent magnet 16, ie, in this example, between the first magnetic gap 23 and the outer peripheral surface of the pole piece 21.
Is formed. Similarly, a second magnetic gap 24 is formed on the second housing 15 side.

A bobbin 2 is provided in the first and second magnetic gaps 23 and 24.
5 and 26, the first and second coils 27,
28 are located respectively. First and second coils 27, 2
Numeral 8 is coaxial with the first and second permanent magnets 16 and 17, and is attached to both plate surfaces of the pendulum 12, respectively. The end faces of the bobbins 25 and 26 on the pendulum 12 side are attached to the mounting plates 25a and 26a.
The mounting plates 25a, 2
6a are bonded and fixed to the pendulum 12, respectively.
The coils 27 and 28 are attached to the pendulum 12.

In this example, the displacement (vibration) of the pendulum 12 is detected by a capacitance type displacement detecting means. On both plate surfaces of the pendulum 12, electrodes 29a and 29b are formed in an arc shape around the first and second coils 27 and 28 by gold plating or the like, and electrodes opposed to these electrodes 29a and 29b are formed on the first and second coils. It is constituted by two housings 14 and 15. For this reason, as shown in the figure, the frame body abuts on the end surfaces of the openings of the first and second housings 14 and 15 sequentially from the outer peripheral side at a portion corresponding to the angular range in which the electrodes 29a and 29b of the pendulum 12 are formed. Surfaces 14b, 15b, escape 14c, 1
5c and electrode surfaces 14d and 15d are formed.
d and 15d are separated by a required amount from the electrodes 29a and 29b of the pendulum 12, respectively.

In the servo accelerometer configured as described above, the pendulum 12 shakes due to the input acceleration in the X direction, and the shake is detected by a change in capacitance between the electrodes 29a and 14d and between the electrodes 29b and 15d. . Electrode surfaces 14d, 15
d is a common GND, and the detection signals of the electrodes 29a and 29b are differentially amplified by a required electric circuit (not shown).
A current is applied to the first and second coils 27 and 28 based on the difference in capacitance between the electrodes 29a and 29b. The current flowing through the first and second coils 27 and 28 and the first and second permanent magnets 1
The pendulum 12 returns to its original position by the action of the magnetic field by 6, 17 and is balanced near the zero point. The current at this time is proportional to the acceleration applied to the pendulum 12, and the input acceleration is obtained from this current.

[0010]

However, in this type of servo accelerometer, there is a strong demand for small size and high performance.
Particularly in terms of performance, improvement in temperature characteristics and a wide measurement range are desired. In order to improve the temperature characteristics (expand the operating temperature range), the dimensional stability of the movable part is important, and furthermore, a structure that minimizes displacement and stress distortion in each component part, especially the movable part, as the temperature of the atmosphere changes. From this point, quartz is used for the frame body 11, the pendulum 12, and the hinge 13, and the first and second housings 14, 1 are used.
5 is made of an invar material having magnetism and conductivity and a small coefficient of thermal expansion.

On the other hand, in order to obtain a wide measurement range, it is necessary to adopt a configuration in which the magnetic circuit does not easily saturate.
The first and second housings 14 and 15 are made of Invar having a saturation magnetic flux density of about 11500 G in view of temperature characteristics, and their magnetic path cross-sectional areas cannot be increased in order to reduce the size. In the conventional structure shown in the above, when the structure is small, the magnetic circuit is saturated, and thus a wide measurement range cannot be obtained, that is, a small servo accelerometer having a wide measurement range cannot be obtained. .

In view of the above problems, an object of the present invention is to provide
It is an object of the present invention to provide a servo accelerometer having a wide measurement range and a small size.

[0013]

According to the present invention, a frame for supporting a pendulum in a frame via a hinge is sandwiched between first and second housings made of a magnetic material, and a central portion of the first and second housings. The first and second permanent magnets are respectively attached to
First and second coils arranged coaxially in first and second magnetic gaps respectively formed between the first and second permanent magnets and the first and second housings are respectively attached to the pendulum. In the servo accelerometer, the first and second housings are provided at portions corresponding to at least between the first and second permanent magnets and the inner peripheral surfaces of the first and second housings on the outer surfaces of the first and second housings. A magnetic reinforcing plate having a higher saturation magnetic flux density is attached.

[0014]

FIG. 1 shows an embodiment of the present invention. Note that FIG.
The same reference numerals are given to portions corresponding to and the description thereof will be omitted. In this example, magnetic reinforcing plates 31 and 32 are attached to the outer surfaces of the first and second housings 14 and 15, respectively. The magnetic reinforcing plates 31 and 32 are made of a material having a higher saturation magnetic flux density than the first and second housings 14 and 15, and the first and second housings 14 and 15 are made of, for example, an invar material (saturation magnetic flux density = 11500G). 1550
Soft magnetic iron material having a saturation magnetic flux density of 0G (JIS C
2503) is used as the material.

The magnetic reinforcing plates 31 and 32 are mounted on the outer surfaces of the bottoms 14a and 15a of the first and second housings 14 and 15 where the first and second permanent magnets 16 and 17 are provided. In the example, disk-shaped magnetic reinforcing plates 31 and 32 having a diameter larger than the diameter of the inner peripheral surfaces 14e and 15e of the first and second housings 14 and 15 are respectively attached. First
The magnetic saturation of the second housings 14 and 15 starts to occur from the portion where the magnetic path cross-sectional area is small, that is, the portion near the center of the bottoms 14a and 15a where the magnetic flux concentrates.
In the middle, the magnetic saturation begins to occur, but in this example, since the magnetic reinforcing plates 31 and 32 are provided in this portion, magnetic saturation is eliminated. Therefore, a large magnetic field can be generated in the first and second magnetic gaps 23 and 24, and the first and second coils 2 and
Since a large force can be applied to 7, 28, a wide measurement range for input acceleration can be realized.

The attachment of the magnetic reinforcing plates 31 and 32 to the first and second housings 14 and 15 is performed by bonding, laser welding, or the like. In this example, the shape of the magnetic reinforcing plates 31 and 32 is changed to the inner peripheral surface 14 of the first and second housings 14 and 15.
The magnetic reinforcing plates 31, 32 have at least the first and second permanent magnets 16,
17 and the inner peripheral surfaces 14e and 15e of the first and second housings 14 and 15, respectively.

[0017]

As described above, according to the present invention, by providing the magnetic reinforcing plates 31 and 32, the magnetic saturation of the first and second housings 14 and 15 can be eliminated and the magnetic reinforcing plates 31 and 32 can be eliminated. , 32 are the first and second housings 14,
Since the first and second housings 1 and 2 have a saturation magnetic flux density higher than 15, for example, to prevent magnetic saturation.
As compared with the case where the thicknesses of 4, 4 and 15 are increased, the thickness can be reduced, so that a small-sized servo accelerometer having a wide measurement range can be obtained.

Since the magnetic reinforcing plates 31 and 32 are added as described above, the first and second housings 14 and
The 15 constituent materials can be selected in terms of the temperature characteristics in relation to the constituent materials of the frame 11, the pendulum 12, and the hinge 13, so that a servo accelerometer excellent in the temperature characteristics can be obtained. it can.

[Brief description of the drawings]

FIG. 1A is a sectional view showing an embodiment of the present invention, and FIG. 1B is a side view thereof.

2A is a cross-sectional view showing a conventional servo accelerometer, and FIG. 2B is a CC cross-sectional view thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Frame 12 Pendulum 13 Hinge 14 1st housing 15 2nd housing 16 1st permanent magnet 17 2nd permanent magnet 23 1st magnetic gap 24 2nd magnetic gap 27 1st coil 28 2nd coil 31, 32 Magnetic reinforcing plate

Claims (1)

(57) [Claims] 1. A frame body for supporting a pendulum in a frame via a hinge is sandwiched between first and second housings made of a magnetic material.
First and second permanent magnets are respectively attached to central portions of the first and second housings, and first and second permanent magnets are respectively provided between the first and second permanent magnets and the first and second housings. First and second coaxially arranged in the second magnetic gap
In a servo accelerometer in which a coil is attached to each of the pendulums, at least between the first and second permanent magnets on the outer surface of the first and second housings and the inner peripheral surface of the first and second housings, respectively. A servo accelerometer, wherein a magnetic reinforcing plate having a higher saturation magnetic flux density than the first and second housings is attached to a corresponding portion.