JPH1164094A - Servo-type vibration detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the displacement feeding back amount and speed feeding back amount of a servo-type vibration detector, based on the displacement of a pendulum detected by means of a displacement detecting section which is independently settable. SOLUTION: A servo-type vibration detector is provided with a first feedback circuit 7A which converts the displacement of a pendulum (m) inputted from an acceleration output circuit into a displacement signal by using a constant As1 and feeds back the displace signal to the input side and a second feedback circuit 7B which converts the displacement of the pendulum inputted from the acceleration output circuit into a speed signal by using a constant As2 and feeds back the speed signal to the input side. Therefore, the displacement feed back amount and the speed feeding back amount of the vibration detector can be set independently.

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 having a plurality of feedback circuits.

[0002]

2. Description of the Related Art First, a servo-type vibration detector will be described with reference to FIG. 5. A servo-type vibration detector 10 includes a case 1 and a driving unit 2, a pendulum 3, and a displacement detection unit 4 provided inside the case 1. 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.
and a drive coil (hereinafter, simply referred to as a "coil") 2b disposed opposite to the coil a. By applying a current to the coil 2b, an electromagnetic force for moving the pendulum 3 to which the coil 2b is attached can be generated. 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). The displacement of the pendulum 3 is detected by measuring the displacement. 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, the acceleration applied to the pendulum 3 can be detected by measuring this current. In order to measure the current (value) i, a load resistor R is provided in the current circuit of the coil 2b.

The above-mentioned conventional servo-type vibration detector incorporates a circuit for extracting an acceleration output as shown in a block diagram of FIG. Symbol m in FIG. 6 indicates the mass of the pendulum, symbol k indicates the spring constant of spring 3a, symbol D indicates the damping constant of damper 3b, symbol α indicates the input acceleration, and symbol e _0.
The output voltage, the symbol As is the constant of the detector 4 (voltage / displacement), the symbols G ₁ is the gain (voltage / voltage) displacement attributable replacement amount of the servo amplifier 5, the symbols G ₂ is speed return of the servo amplifier 5 The symbol Af indicates the constant (force / current) of the drive unit 3, and the transfer function e ₀ / α in this circuit is represented by the following [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 extracting the acceleration output of the servo-type vibration detector, the output of one displacement detector 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.

[0009]

In the servo type vibration detector, mechanical instability such as a spring can be removed by applying displacement feedback to stabilize the sensitivity and the like. 7A, the frequency characteristics of the vibration detector are changed from the characteristics shown in FIG. 7A to the characteristics shown in FIG. .

By the way, as in the prior art, the velocity feedback signal and the displacement feedback signal obtained based on the displacement of the pendulum obtained from one displacement detecting section are fed back to the input side via one driving section. In the configuration,
There is a problem that the respective feedback amounts of the displacement feedback and the velocity feedback are restricted to each other, and the respective feedback amounts cannot be set independently.
The present invention is intended to solve such a problem.

[0011]

According to the present invention, there is provided a case, a drive unit provided in the case, a pendulum movably provided in the case via a spring, and a displacement of the pendulum. A displacement detection unit, and a servo amplifier capable of supplying a current for causing the drive unit to generate an electromagnetic force for returning the pendulum to a zero position when the displacement of the pendulum from the zero position is detected by the displacement detection unit. A feedback that feeds a displacement feedback amount and a speed feedback amount set based on the displacement of the pendulum detected by the displacement detection unit to a comparator on the input side of acceleration as displacement feedback and speed feedback via the driving unit. In a servo-type vibration detector equipped with a circuit, the above-described displacement feedback and velocity feedback are performed independently of each other. Ubeku, and a means of solving the problems constituted by two independent systems of feedback circuit.

Further, in order to form the above-mentioned two independent feedback circuits, two driving units, two displacement detecting units, and two servo amplifiers are provided to solve the problem.

In the present invention, since the displacement feedback circuit and the speed feedback circuit are composed of two independent circuits, the displacement feedback amount and the speed feedback amount can be independently set without being restricted by each other.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A servo type vibration detector according to an embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram thereof, FIG. 2A is a side sectional view of the displacement detection unit, FIG. 2B is a sectional view taken along line AA of FIG. 2A, and FIG.
FIG. 4 is an exploded perspective view of a main part of the cross spring joint, FIG. 4B is an exploded perspective view of the same, and FIG. 4 is a circuit diagram of the acceleration output. The same reference numerals as in FIGS. 5 and 6 in FIGS. 1 to 4 denote substantially the same members.

As shown in FIG. 1, the servo type vibration detector of this embodiment also includes a case (not shown), a drive unit 2, a pendulum 3, a displacement detection unit 4, and a servo amplifier provided inside the case. 5.

The drive section 2 includes a magnet 2a, a first drive coil 21 and a second drive coil 22 wound around the pendulum 3 and arranged to face the magnet 2a (hereinafter, referred to as "first coil", respectively).
21 "and" second coil 22 "). Sign
Reference numeral 11 denotes a cylindrical bearing of the pendulum 3.

As shown in FIG. 2, the displacement detecting section 4 includes a pair of fixed side pole plates 41 and a pair of fixed side pole plates 41, and a pendulum side pole plate 31 interposed therebetween. Each fixed side plate
Conductors 45a and 46a forming a first electrode (capacitor) 45 and a second electrode (capacitor) 46 are attached to the opposing surfaces of the 41 and the pendulum-side electrode plate 31 via insulating plates, respectively. First and second two displacement detectors 4A, 4
B.

The pendulum-side electrode 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 move like a seesaw around an axis 13 (described later).

That is, as shown in FIGS. 3A and 3B,
Cross spring joint is a ring member that can be fitted to cylindrical bearing 11
A leaf spring 3c having one end fixed to 12a;
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 so that the two ring members 12a and 12b are oriented in the direction perpendicular to each other.
The other end of each of the leaf springs 3c, 3d is connected to the other ring member 12b, 12b as shown in FIG.
a through the same connecting member 14.

The servo amplifier 5 is also composed of a first servo amplifier 5A to which the output of the first displacement detecting section 4A is input and a second servo amplifier 5B to which the output of the second displacement detecting section 4B is input. . In the first servo amplifier 5A, the current control for the first drive coil 21 is performed by the first servo amplifier 5A so as to match the first drive unit 2A and the first displacement detection unit 4A. The same applies to the relationship between the second servo amplifier 5B and the second drive unit 2B.

The detection of the vibration speed is performed based on the amount of current i ₁ of the first drive coil 21, and the amount of current i of the second drive coil 22 is detected.
_{From 2,} the acceleration applied to the pendulum 3 can be detected. R ₁ and R ₂ indicate load resistances for that.

In this embodiment, as described above, the displacement detecting unit, the driving unit, and the servo amplifier are each composed of two independent displacement detecting units and the driving unit.
The output of the system can be taken out, and the circuit for taking out the acceleration output is also composed of two independent circuits.

That is, as shown in FIG. 4, the output of the first detection unit 4A is converted into a displacement signal by the filter circuit of the first servo amplifier 5A in the circuit of the first detection unit 4A, and the first drive unit 2A A first feedback circuit 7A for providing a displacement feedback to the comparator P on the input side via the input circuit is provided. The output of the second detection unit 4B is applied to a circuit of the second detection unit 4B system by a filter of the second servo amplifier 5B. A second feedback circuit 7 which converts the signal into a speed signal by a circuit and feeds back the speed to the comparator P on the input side via the second drive unit 2B;
B is provided. And both feedback circuits 7
A and 7B constitute independent feedback circuits.

The transfer function in each circuit shown in FIG.
Solving for the output voltages e ₀₁ and e ₀₂ gives:
[Equation 3] is obtained.

## EQU2 ## e ₀₁ / α = (m · As ₁ · G ₁ ) / [mS ² +
(D + As ₂ · G ₂ · Af ₂ ) S + k + As ₁ · G ₁ · A
f ₁ ]

## EQU3 ## e ₀₂ / α = (m · As ₂ · G ₂ · S) / [mS ²
+ (D + As ₂ · G ₂ · Af ₂ ) S + k + As ₁ · G ₁ · A
f ₁ ]

Here, G ₁ and G ₂ represent transmission functions of the first servo amplifier 5A and the second servo amplifier 5B, respectively. Af ₁ and Af ₂ are constants (force / current) of the first drive unit 2A and the second drive unit 2B, and AS ₁ and AS ₂ are constants (force / current) of the first detection unit 4A and the second detection unit 4B. (Voltage / displacement).

As described above, since the displacement feedback circuit and the speed feedback circuit are constituted by independent circuits, the respective feedback amounts of the displacement feedback and the speed feedback can be set independently without being restricted by each other. become.

Also, since the setting of each feedback amount can be performed independently of each other, even when, for example, the displacement feedback cannot be applied due to the restriction of the power supply voltage of the servo amplifier, the speed feedback operates independently, and the larger input can be obtained. Vibration can be measured.

In the conventional device (see FIG. 6), since there is only one feedback circuit, in the above case, both the feedback of the displacement and the speed do not take place at the same time. Such inconvenience disappears.

[0029]

As described above in detail, according to the servo type vibration detector of the present invention, the displacement feedback circuit and the speed feedback circuit are constituted by two independent circuits, so that they are mutually restricted. There is an effect that the displacement feedback amount and the speed feedback amount can be set independently without any need.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a servo vibration detector as one embodiment of the present invention.

2A is a side sectional view of the displacement detection unit, and FIG.
FIG. 3A is a cross-sectional view taken along line AA.

3A is an exploded perspective view of a main part of a cross spring joint, and FIG. 3B is an exploded perspective view of the same.

FIG. 4 is a circuit diagram for extracting the acceleration output.

FIG. 5 is a schematic configuration diagram of a conventional servo vibration detector.

FIG. 6 is a circuit diagram for extracting the acceleration output.

FIGS. 7A and 7B are diagrams showing frequency characteristics of the vibration detector. FIGS.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 2 Drive part 2A 1st drive part 2B 2nd drive part 2a Magnet 2b Drive coil 3 Pendulum 3a Spring 3b Damper 3c, 3d Leaf spring 4 Displacement detection part 4A 1st displacement detection part 4B 2nd displacement detection part 4a, 4b Electrode plate 5 Servo amplifier 5A First servo amplifier 5B Second servo amplifier 7 Feedback circuit 7A First feedback circuit 7B Second feedback circuit 11 Bearing 12a, 12b Ring member 13 Axis 14 Connecting member 21 First drive coil 22 Second drive coil 31 Pendulum side plate 40 Capacitor 41 Fixed side plate 45 First electrode (first capacitor) 46 Second electrode (second capacitor) 45a, 46a Conductor

Claims (2)

[Claims] 1. A case, a drive unit provided in the case, a pendulum movably provided in the case via a spring, a displacement detector for detecting displacement of the pendulum, and a displacement detector A servo-type vibration detector including a servo amplifier capable of supplying a current that causes the drive unit to generate an electromagnetic force for returning the pendulum to the zero position when the displacement of the pendulum from the zero position is detected by the unit; A feedback circuit that feeds back a displacement feedback amount and a speed feedback amount set based on the displacement of the pendulum detected by the displacement detection unit to the comparator on the input side of acceleration as the displacement feedback and the speed feedback via the driving unit; In order to perform the above-mentioned displacement feedback and velocity feedback independently of each other, the feedback circuit is independent. A servo type vibration detector characterized by comprising two systems. 2. The servo according to claim 1, wherein the drive unit, the displacement detection unit, and the servo amplifier are provided two each so as to form the independent two-system feedback circuit. Type vibration detector.