JPH07253356A - Vibration speed meter - Google Patents

Abstract

PURPOSE:To have sufficient measurement accuracy and yield strength against lightning surge and EMI even if a vibration speed meter is installed on a high- rise building having an altitude of 300m. CONSTITUTION:A detection output of an acceleration sensor 2 such as a servo acceleration meter is input through a band filter 5 which removes noise out of a band and also cuts DC components to an integration circuit 6 where it is converted into a speed signal, the output is converted via a V/I-converter 7 or a V/F-converter 8 into a current or frequency signal as necessary, either of the signals is selected by a switch 9 and supplied through an EMI filter 14 to a speed output terminal Ov. The EMI filter 14 and an arrester 13 for preventing lightening surge from entering are provided on all terminal sides such as a power supply terminal. The integration circuit 6 comprises a circuit containing a primary HPF with a primary LPF cascaded. This apparatus is housed in a single shield case.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration velocimeter applied to a high-rise building or a large structure, and more particularly to a high-rise building to which it is applied.

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional vibration velocity meter 1 of this type has an acceleration sensor 2 such as a servo type accelerometer.
Vibration acceleration signal a (t) (t is time) which is the detection output of
Is input to the integrator unit 4 installed at a place far away from the acceleration sensor 2 for integration, that is, v (t) = ∫a (t) dt (1) The velocity signal v (t) is obtained. , V (t) is output to the outside.

Now, the acceleration signal a (t) and the velocity signal v
The Laplace transform of (t) is A (s), V (s), respectively.
(S is a Laplace variable). That is, A (s) = La (t); V (s) = Lv (t) (2) In the equation (2), L is a symbol of Laplace transform. If both sides of the equation (1) are Laplace transformed, it is well known that V (s) = A (s) (1 / s) (3) In equation (3), (1 / s) is nothing but the ideal transfer function G (s) of the integrator unit 4. That is, G (s) = 1 / s (4) The integrator unit 4 is provided with a bandpass filter 5 on the input side of the integrator circuit 6 in order to remove out-of-band noise components and cut DC components. However, the pass band is set to be wider by about one digit or more so as not to affect the electric characteristics of the integrating circuit 6 in the band necessary for vibration measurement (for example, 0.1 to 20 Hz), for example, 0.01 to It is set to 1 KHz. Therefore, the integration characteristic of the integrator unit 4 can be treated as depending only on the characteristic of the integrating circuit 5.

As shown in FIG. 7, an integrating circuit composed of an operational amplifier OA, a resistor R ₀ and an integrating capacitor C ₀ is well known. Acceleration signal input a (t) of this circuit
The relationship between the velocity signal output v (t) for, v (t) = - ( 1 / C 0 R 0) ∫a (t) dt = -K∫a (t) dt ...... (5) K = 1 / C ₀ R ₀ (6) The transfer function of this circuit is expressed by G ₀ (s) =-K (1 / s) (7). By the way, when the drift voltage is input to the integrating circuit of FIG. 7 due to lightning surge or induced noise due to EMI, etc., the integrating capacitor C ₀ is charged, which causes a measurement error, which is not preferable.

Conventionally, since the acceleration sensor and the integration unit are separated from each other, they are easily affected by inductive noise due to lightning surge or EMI, but no special measures have been taken.

[0006]

In recent years, the number of high-rise buildings has been increasing year by year and the number of them has been increasing.
Vibration measuring instruments are becoming more important for earthquake countermeasures of high-rise buildings. However, when the conventional vibration velocity meter is applied to a high-rise building with a height of 100 m or more, the measurement error suddenly becomes large, and there is a drawback that the measurement is hindered. In addition, the higher the building height, the greater the effect of lightning surges, which has the drawback of being prone to failure. An object of the present invention is to solve these conventional drawbacks and to provide a vibration velocity meter having sufficient measurement accuracy and lightning surge resistance even when applied to a high-rise building with a height of 300 m, and which can withstand practical use. To do.

[0007]

[Means for Solving the Problems]

(1) A vibration velocimeter that integrates the output of a vibration acceleration sensor by an integration circuit to obtain a vibration speed and outputs a signal corresponding to the vibration speed. In the invention of claim 1, the vibration acceleration sensor is built in. It is housed in one shield case, and the integrating circuit is composed of a circuit in which a primary high-pass filter and a primary low-pass filter are connected in cascade.

(2) According to a second aspect of the invention, in the vibration velocity meter according to the first aspect, arresters for protecting the device from lightning surges are attached to the device input and output ends of the signal and the power source, respectively. (3) According to the invention of claim 3, in the vibration velocity meter according to (1) or (2), the EMI countermeasure filters are attached to the device input / output terminals of the signal and the power supply, respectively.

[0009]

[Example] The primary vibration period (primary natural period) T ₁ (seconds) of a large number of high-rise buildings whose domestic height is 50 to 300 m (about 70 floors above the ground) and the height h (m) of the building As a result of investigating the relationship of the above, it was found that the primary vibration cycle T ₁ can be expressed by T ₁ ≈0.02h to 0.03h (8).

From the equation (8), for example, when the height is 300 m, T ₁ ≈ 6-9 seconds, f ₁ = 0.17-0.11 Hz, and an earthquake or the like is observed in a high-rise building of about 300 m class. In order to provide a vibration velocimeter that can be used for high accuracy and to accurately measure high-order components of structures with a short vibration period such as low-rise buildings and nuclear power plants, a good frequency in the range of 0.1 to 50 Hz is used. It is desirable to have characteristics.

As described in the prior art, the ideal transfer function of the integrator circuit is K (1 / s), where K is a constant. Therefore, its amplitude (gain) frequency characteristic is | G ₀ ( jω) | = 20log ₁₀ K−20log ₁₀ 2πf = 20log ₁₀ (K / 2π) −20log ₁₀ f (9) The phase characteristic is θ (ω) = ∠ (1 / jω) = − π / 2 (rad) = -90 ° (10) Therefore, the ideal integrator circuit has a level of 20 dB per decade (every 10 times increase in frequency f).
It has a decreasing amplitude characteristic and a phase characteristic in which the amount of phase (shift) of the output with respect to the input is −90 °.

Examining a conventional vibrometer, the frequency is 0.5 Hz or less (converted to the height of the building, about 70 m or more)
Then, it was found that the deviation of the phase amount from −90 ° sharply increased and exceeded 30 °, which was one of the causes of the increase in the measurement error. (Experimentally it is considered that the practical limit is a phase deviation of about 30 °.) The reason why there are many deviations from the ideal integration characteristic is that the approximation accuracy of the transfer function on the ultra-low frequency side is poor. That is, the capacitance value of the capacitor exceeds 100 μF, and it is impossible to obtain a capacitor having good accuracy and electrical and mechanical characteristics.

Therefore, according to the present invention, as a speedometer applicable to a high-rise building of a class from low to 300 m, in a frequency band of 0.1 to 50 Hz, the vibration characteristic has a problem of deviation from a straight line having a slope of -20 dB / decade. The degree of deviation (for example, 1 dB or less) is set to a value that does not occur, and the deviation of the phase characteristic, which is a problem of the conventional technology, from −90 ° is, of course, within 30 °, but a vibration control system using a speedometer can be configured. In order to do so, the target is about 10 °. In the vibration control system, the phase characteristic is as important as the amplitude characteristic.

According to recent research, it has been found that the effect of EMI and lightning surge increases as the height of the building increases, which is also one of the factors that increase the measurement error. In particular, when a direct-current drift voltage is input to the integrating circuit 6 due to a lightning surge or the like, the terminal voltage of the capacitor gradually increases, resulting in a measurement error. Further, it takes a long time for the integrator unit to return to a steady state, which hinders measurement.

The bandpass filter 5 is inserted in the preceding stage in the integrator unit 4 to cut the direct current component. However, when the circuit is mounted on the printed circuit board, the wiring between the bandpass filter 5 and the integrating circuit 6 is to some extent. Of the EMI and lightning surge may be induced between them. Therefore, in the present invention, the DC component is cut by the high-pass filter immediately before the start of integration.

FIG. 2 shows an integrating circuit used in the embodiment, which is H
The PF (high-pass filter) includes a capacitor C ₁ and a resistor R ₁
It is composed of a circuit in which buffers Ba and Bb are provided at the input and output ends of the inverted L-shaped circuit. Its transfer function G _H is first-order,
As is well known, G _H = T · s / (T _H · s + 1) (11) T _H = C ₁ R ₁ (12) The integral characteristic of the circuit of FIG. 2 is that of a first-order LPF (low-pass filter). As is well known, the transfer function is G _L = T _L K _L / (T _L · s + 1) (13) T _L = C ₂ R ₂ (14) K _L = 1 / C ₂ represented as R ₃ ...... (15).

T_H= T_L= 18.24 (seconds),
C₁= C₂= 20μF, R ₁= R₂= 912.0
It becomes 1 KΩ. If K_LIf = 1 then R₃= 1 / C₂
= 50 KΩ. Also K_LT_L= 1, ie K_L= 1 /
T_LThen, from equation (15), C₂R₃= T_LWill be
Then this T_LSubstituting equation (14) into₃= R₂= 91
It becomes 2.01KΩ. The transmission frequency band is an ultra-low frequency band
However, the capacitance value is relatively small at 20 μF,
Since the resistance value is less than 1 MΩ, the capacitor and resistance
Good equipment accuracy, electrical characteristics, vibration resistance, shock resistance, etc.
Good mechanical properties will be available. The final stage
The AMP (amplifier) is for gain adjustment.

FIGS. 3 and 4 show the respective frequency characteristics of the overall gain and phase amount in which the bandpass filter 5 is provided in front of the integrating circuit 6 thus constructed. As is clear from these figures, the amplitude characteristic (gain frequency characteristic) is 0.03 to 100.
It shows a slope characteristic of −20 dB / decade at Hz, and the error is small enough to be ignored. Further, the deviation of the phase amount from -90 ° is about 11 ° at 0.1 Hz, which is almost the same as the target value.

In the embodiment shown in FIG. 1, the voltage output of the integrating circuit 6, the output obtained by converting this output into a current through the V / I converter 7, and the output obtained after converting the voltage output into a frequency through the V / F converter 8. Either of these can be selected by the switch 9. In addition to the speed output, the switch 12 selects either the voltage output of the acceleration sensor 2, the output of the voltage output through the V / I converter 10, or the output of the V / F converter 11 as well. I am trying to output it.
In addition, a circuit for self-test and the like are mounted on the device, but they are omitted because they are not related to the invention.

In the conventional device, the connection portion between the acceleration sensor 2 and the cable 3, the connection between the cable 3 and the integrator unit 4, the cable 3 itself, the input / output terminal and the power supply terminal, the EMI,
Noise such as lightning surge may intrude, increasing the measurement error and destroying the circuit. In this invention,
As measures against lightning surges and EMI in such high-rise buildings,
The acceleration sensor 2 and the integration circuit unit 4 are separated and the conventional method of connecting them with a cable 3 is stopped, both are housed in the same shield case 20, and the signal output terminal O _v , O _a and insert the arrester 13 between all terminals and frame ground and power terminals O _P prevents the penetration of lightning surge current and the signal line and the power supply line connected to the signal input and output terminals and power supply terminal The filter 14 for EMI countermeasure is inserted.

In the shield case 20, the arrester 1
3, an environment-resistant substrate 21 on which the EMI filter 14 and the like are mounted,
An integrating circuit board 22, a bandpass filter / power supply circuit board 23, and an acceleration sensor (servo accelerometer) 2 are housed.

[0022]

The present invention employs an integral structure in which the acceleration sensor and the integrator unit (including the bandpass filter 5 and the integrating circuit 6) are housed in the same shield case 20. All terminals such as signal terminals and power terminals are provided with arresters and EMI countermeasure filters.

An integrator circuit is connected in series with a primary high-pass filter on the input side and a primary low-pass filter on the output side so that the integrator circuit itself generates a direct current component or a direct current caused by a lightning surge or EMI, or a direct current. We try not to integrate near ultra-low frequency drift. By improving the accuracy of approximation to the ideal integral characteristic of the integrator circuit on the ultralow frequency side and realizing the integral characteristic by a first-order low-pass filter, the constant of the integrating capacitor can be set smaller than before, You can select the one with good accuracy and characteristics.

As a result, it is possible to realize a vibration velocity meter having practically sufficient measurement accuracy, lightning surge and EMI resistance even when applied to a high-rise building up to a height of 300 m class (about 70th floor).

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of an integrating circuit 6 shown in FIG.

3 is a diagram showing transfer characteristics of a cascade circuit of a bandpass filter 5 and an integrating circuit 6 of FIG.

FIG. 4 is an enlarged view of a main part of FIG.

5 is a perspective view showing the outline of the mounting structure of the embodiment of FIG.

FIG. 6 is a block diagram showing a configuration of a conventional vibration velocity meter.

7 is a circuit diagram showing an example of an integrating circuit 6 in FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Motoichi Takahashi 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Naoki Niwa 1-2-2 Moto-Akasaka, Minato-ku, Tokyo 7 Kashima Construction Co., Ltd. (72) Inventor Kurata Adults 1-2-7 Moto Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Inventor Kobayashi ▲ Taka ▼ 1-21, Dogenzaka, Shibuya-ku, Tokyo No. 6 in Japan Aviation Electronics Industry Co., Ltd. (72) Inventor Katsuhiko Umezu 1-21-6 Dogenzaka, Shibuya-ku, Tokyo No. 6 in Japan Aviation Electronics Industry Co., Ltd. No. 6 Japan Aviation Electronics Industry Limited

Claims (3)

[Claims] 1. A vibration velocimeter that integrates the output of a vibration acceleration sensor by an integration circuit to obtain a vibration speed and outputs a signal corresponding to the vibration speed, wherein the vibration acceleration sensor is built in and one shield case is provided. A vibration velocimeter, which is housed inside, wherein the integrator circuit is composed of a circuit in which a primary high-pass filter and a primary low-pass filter are connected in cascade. 2. The vibration velocity meter according to claim 1, wherein an arrester for protecting the device from lightning surges is attached to each of the signal input / output terminals of the signal and the power source. 3. The vibration velocity meter according to claim 1 or 2, characterized in that filters for EMI countermeasures are attached to the input / output terminals of the signal and power supply.