JPH11118586A - Servo-type vibration detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the load of a drive system and to miniaturize a servo-type vibration detector by a method wherein a pendulum is arranged and installed in such a way that its rocking center is brought close to the center of gravity of the pendulum. SOLUTION: A pendulum 3 is installed at the inside of a case 1 for a servo- type vibration detector so as to be rockable in a seesaw shape via a spring, and the position of the center of gravity W of the pendulum 3 is set so as to be brought very close to its rocking center R. A part of the pendulum 3 may be constituted of metals or the like whose specific gravity is different. When the rocking center R is brought close to the center of gravity W, the load of a drive system for the servo-type vibration detector can be reduced, and a drive part can be miniaturized. Consequently, the servo-type vibration detector can be miniaturized. In addition, as an equalizer spring, a spring whose constant is small can be used, and the natural frequency of the pendulum 3 is not changed too much.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo-type vibration detector, and more particularly to a servo-type vibration detector capable of being downsized.

[0002]

2. Description of the Related Art First, a servo type vibration detector will be described with reference to FIGS.
Case 1 and driving units 2 provided inside the case 1
It is composed of a pendulum 3, a displacement detector 4, and a servo amplifier 5.

A driving unit 2 is wound around a magnet (permanent magnet) 2a fixed to a case 1 and a pendulum 3 to form a magnet 2a.
The drive coil (hereinafter simply referred to as a “coil”) 2b is disposed opposite to “a”, and an electromagnetic force for moving the pendulum 3 to which the coil 2b is attached can be generated by passing a current through the coil 2b. ing. A spring 3a and a damper 3b are interposed between the pendulum 3 and the magnet 2a in parallel.

[0004] The displacement detection unit 4 is provided with a capacitor 40 formed between the electrode plate 4a attached to the pendulum 3 and the electrode plate 4b on the case 1 side (fixed side) to measure the electric capacitance between the two electrode plates 4a and 4b. By measuring the displacement, the swing displacement of the pendulum 3 is detected. The servo amplifier 5 is provided for matching the drive unit 2 and the displacement detection unit 4.

In the above arrangement, when acceleration is applied to the pendulum 3 and the pendulum 3 deviates from the zero position, the displacement detecting section 4 detects this deviation (amount), and upon receiving the signal, the servo amplifier 5 causes the coil 2b of the driving section 2 to operate. It operates to supply current to the.

This current generates a force (electromagnetic force) in the direction opposite to the displacement of the pendulum 3, and acts to return the pendulum 3 to the zero position. Since this electromagnetic force is balanced with the acceleration that caused the pendulum 3 to shift, by measuring this current,
The acceleration applied to the pendulum 3 can be detected.

In order to measure the current (value) i, the coil 2
A load resistor R is provided in the current circuit b. And
The above-described conventional servo-type vibration detector incorporates a circuit for extracting an acceleration output as shown in a block diagram of FIG.

The symbol m in FIG. 3 is the mass of the pendulum, the symbol k is the spring constant of the spring 3a, the symbol D is the damping constant of the damper 3b, the symbol α is the input acceleration, the symbol e ₀ is the output voltage, symbols As, the sensor 4 constant (voltage / displacement), the symbols G ₁ is a servo amplifier 5 gain (voltage / voltage) displacement attributable replacement amount,
The symbol G ₂ indicates the speed conversion amount (including differential characteristics) of the servo amplifier 5, and the symbol Af indicates the constant (force / current) of the drive unit 3, and the transmission function e ₀ / α in this circuit.
Is represented by [Equation 1].

[Equation 1] e ₀ / α = (m · As · G ₂ · S + m · As ·
G ₁ ) / [mS ² + (D + Af · As · G ₂ ) S + k +
Af · As · G ₁ ] where S is a complex number operator.

As described above, in the conventional circuit for taking out the acceleration output of the servo type vibration detector, the output of one displacement detecting unit 4 is converted into a signal of displacement and speed, and based on the displacement signal and speed signal. The displacement feedback amount is calculated by the first filter circuit 6a built in the servo amplifier 5.
In addition, the speed feedback amounts are set by the second filter circuit 6b (the second filter circuit 6b includes an electric differentiating circuit), and the respective feedback amounts are fed back to the input side comparator P via one drive unit 2. In addition, a feedback circuit 7 for correcting the characteristic (mS ² + DS + k) of the pendulum 3 is incorporated.

As shown in FIGS. 4A and 4B, the displacement detecting section 4 includes a pair of fixed-side electrode plates 41 and a pair of fixed-side electrode plates 41, 41.
A conductor 45a forming an electrode (capacitor) 45 is provided on an opposing surface of each fixed-side electrode plate 41 and each pendulum-side electrode plate 31 with an insulating plate. It is formed by being attached to each other.

The pendulum-side pole plate 31 is connected to the pendulum by a cross spring joint in which a pair of leaf springs 3c and 3d are arranged in a cross shape, and a geometrical intersection of the pair of leaf springs 3c and 3d. It can swing like a seesaw around an axis 13 (described later).

That is, as shown in FIGS. 5A and 5B,
The cross spring joint is a cylindrical bearing 11 fixed to the case 1.
A leaf spring 3c having one end fixed to a ring member 12a that can be fitted to the plate spring, and a leaf spring 3d having one end fixed to a ring member 12b that can be fitted to the cylindrical large-diameter portion 32 of the pendulum-side electrode plate 31. And
The two ring members 12 are oriented at right angles to each other.
a and 12b are arranged on the same central axis 13, and the other ends of the leaf springs 3c and 3d are connected to the other ring members 12b and 12a by the same connecting member 14 as shown in FIG. It is constituted so that it may be connected via.

[0013]

By the way, conventionally, regarding the pendulum 3, the positional relationship between (the position of) the center of gravity W of the pendulum 3 and the rotation center R (see FIG. 6) of the pendulum 3 is taken into consideration. Therefore, in the conventional servo vibration detector, the center of gravity W of the pendulum 3 is far away from the center of rotation R, and the distance L between the two is large. As a result, the load on the drive unit [the pendulum returns to the zero position] Therefore, there is a problem that the drive unit becomes large and the servo type vibration detector becomes large. The present invention
It is intended to solve such a problem.

[0014]

SUMMARY OF THE INVENTION The present invention provides a case, a drive unit provided in the case, a pendulum provided in the case via a spring so as to be swingable in a seesaw shape, and a pendulum. A displacement detector for detecting a swing displacement, and a current for causing the drive unit to generate an electromagnetic force for returning the pendulum to a zero position when the swing detector detects a swing displacement from the zero position of the pendulum. In a servo-type vibration detector having a possible servo amplifier, a displacement feedback amount and a speed feedback amount set based on the displacement of the pendulum detected by the displacement detection unit are input to the acceleration through the drive unit. A feedback circuit for providing feedback as displacement feedback and velocity feedback to the comparator on the side of the pendulum so that the center of oscillation of the pendulum approaches the center of gravity of the pendulum. It is a means of solving the problems and set.

Also, a case, a drive unit provided in the case, a pendulum provided in the case so as to be swingable in a seesaw manner via a spring, and a displacement detector for detecting a swing displacement of the pendulum. A servo amplifier capable of supplying a current for causing the drive unit to generate an electromagnetic force for returning the pendulum to the zero position when the swing detection of the pendulum from the zero position is detected by the displacement detection unit. In the servo-type vibration detector, the displacement feedback amount and the speed feedback amount set based on the displacement of the pendulum detected by the displacement detection unit are subjected to displacement feedback to the comparator on the input side of acceleration via the drive unit. It has a feedback circuit that performs feedback as velocity feedback, and forms the pendulum into a shape that makes the center of its swing close to the center of gravity of the pendulum. It is set to.

In the present invention, the load on the drive system is reduced, and the size of the servo vibration detector can be reduced.
Further, in the case of detecting vertical vibration, a balancing spring for 1 G (gravity) is provided. By reducing the vibration system load, this balancing can be performed with a spring having a small spring constant.
The natural frequency of the pendulum does not change much.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A servo-type vibration detector according to one embodiment of the present invention will be described below with reference to the accompanying drawings. 2 to 6 in FIG.
The same reference numerals indicate substantially the same members.

The servo type vibration detector of this embodiment has substantially the same structure as that of the above-mentioned conventional type, and the pendulum 3 also has the same mechanism as that of the above-mentioned conventional type of servo type vibration detector.
The servo type vibration detector is provided inside the case 1 so as to be swingable in a seesaw shape via a spring.

In this embodiment, the position of the center of gravity W of the pendulum 3 and the center of swing R are extremely close to each other, that is, the distance L between the center of gravity W of the pendulum 3 and the center of swing R is L ≒ 0. The pendulum 3 is disposed such that

As one means for disposing the pendulum 3 as described above (so that L ≒ 0), the pendulum 3 may be processed into a shape capable of achieving the above-mentioned purpose. . The “shape” in this case includes not only a geometric shape but also a case where a part of the pendulum 3 is made of a metal having a different specific gravity.

As described above, the swing center R of the pendulum 3 is set at the center of gravity W.
, The load on the drive system of the servo-type vibration detector (the drive unit for returning the pendulum 3 to the zero position) can be reduced, and the drive unit can be downsized. Can be reduced in size.

When a servo type vibration detector is installed to detect vertical vibration, a balancing spring for 1 G (gravity) is provided, but the load on the drive system can be reduced. Even if the spring has a small spring constant, the initial purpose can be sufficiently achieved, and as a result, the natural frequency of the pendulum 3 does not change much. Further, the initial purpose can be achieved by a simple means of changing the shape of the pendulum 3, which is advantageous in terms of manufacturing cost.

[0023]

As described above, according to the servo type vibration detector of the present invention, the following effects can be obtained. (1) By bringing the swing center of the pendulum closer to the center of gravity, the load on the drive system (drive unit that returns the pendulum to the zero position) of the servo-type vibration detector can be reduced, and the drive unit can be downsized. As a result, the size of the servo-type vibration detector can be reduced. (2) When a servo-type vibration detector is installed to detect vertical vibration, a balancing spring for 1 G (gravity) is provided. However, since the load on the drive system can be reduced, the balancing spring is used. As a result, even if the spring constant is small, the initial purpose can be sufficiently achieved, and as a result, the natural frequency of the pendulum 3 does not change much. (3) The initial purpose can be achieved by a simple means of changing the shape of the pendulum, which is advantageous in terms of manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a main part of a servo type vibration detector as one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional servo vibration detector.

FIG. 3 is a circuit diagram for extracting the acceleration output.

FIG. 4A is a side sectional view of the displacement detection unit. (b) The sectional view on the AA arrow of a figure (a).

FIG. 5A is an exploded perspective view of a main part of the cross spring joint. (b) The exploded perspective view.

FIG. 6 is a schematic explanatory view showing the main part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 2 Drive part 2a Magnet 2b Drive coil 3 Pendulum 3a Spring 3b Damper 3c, 3d Leaf spring 4 Displacement detection part 4a Polar plate 5 Servo amplifier 7 Feedback circuit 11 Bearing 12a, 12b Ring member 13 Axis 14 Connecting member 31 Pendulum side pole Plate 41 Fixed side plate 45 Capacitor R Center of vibration of pendulum W Center of gravity of pendulum

Claims (2)

[Claims] 1. A case, a drive unit provided in the case, a pendulum provided in the case via a spring so as to be swingable in a seesaw shape, and a displacement detector for detecting a swing displacement of the pendulum. And a servo amplifier capable of supplying a current for causing the drive unit to generate an electromagnetic force for returning the pendulum to the zero position when the swing detection of the pendulum from the zero position is detected by the displacement detection unit. In the servo-type vibration detector, the displacement feedback amount and the speed feedback amount set based on the displacement of the pendulum detected by the displacement detection unit are subjected to displacement feedback to the comparator on the input side of acceleration via the drive unit. A feedback circuit for feeding back as speed feedback, wherein the pendulum is arranged so that its swing center is close to the center of gravity of the pendulum. A servo-type vibration detector. 2. A case, a drive unit provided in the case, a pendulum provided in the case via a spring so as to be swingable in a seesaw shape, and a displacement detector for detecting a swing displacement of the pendulum. A servo amplifier capable of supplying a current for causing the drive unit to generate an electromagnetic force for returning the pendulum to the zero position when the swing detection of the pendulum from the zero position is detected by the displacement detection unit. In the servo-type vibration detector, the displacement feedback amount and the speed feedback amount set based on the displacement of the pendulum detected by the displacement detection unit are subjected to displacement feedback to the comparator on the input side of acceleration via the drive unit. A feedback circuit for performing feedback as speed feedback is provided, and the pendulum is formed in a shape that brings the center of its swing close to the center of gravity of the pendulum. A servo-type vibration detector.