JPH0340331B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to the structure of a sensor for a vibration/acoustic measuring device that determines the operating status, failure, and safety of equipment during operation.

<Prior art and its problems> When an object vibrates, it emits sound. When a device with a rotating body is operating smoothly, there is little vibration and the sound it makes is steady and has a rhythm.

The driver usually hears the sound with his ears and touches the outer box of the rotating device to memorize its normal state, and if there is a sound or vibration that differs from this, he considers it abnormal and takes appropriate measures.

However, due to recent advances in sensors, devices that are superior to human senses have been developed, and there are means to display equipment safety precautions numerically or on screen, and to ensure more accurate and precise detection and safety. provided.

As a sensor, a microphone is usually used to measure and detect sound, and a vibration acceleration pick-up, displacement pick-up, vibration velocity pick-up, etc. are used to measure vibration.

Conventionally, vibrations have been the main method used to diagnose abnormalities in machinery and plants and monitor operating conditions, but recently, monitoring of sounds has been increasing.

For example, when diagnosing an abnormality in a bearing or impeller of a rotating machine such as a turbine or a pump, vibration and sound at one point may be measured and the abnormality diagnosed based on the combined signals of both.

In this case, it would be most reliable to directly measure the sound from the bearing inside the bearing or the impeller inside the scroll (spiral casing), but this is not possible due to the structure of the equipment. A sensor is placed in contact and the transmitted sound is measured.

In addition, in the past, the sound was often measured by the sound pressure level, but in recent years, with the development of FFT (Fast Fourier Transformer) analyzers, the sound intensity (strength) is measured and the sound power (output) is measured. There are more and more things to do.

The methods for measuring sound intensity can be broadly classified into: (1) when two microphones are used, and (2) when one microphone (surf intensity) is used in combination with a vibration acceleration pickup. In the latter case (2), conventionally the microphone and vibration acceleration pickup use separate sensors, so even if they are placed close to each other, it does not mean that the sound and vibration were measured at the same point. This causes a phase delay and a phase difference, making it impossible to measure to obtain correct data.

The sensor of the present application was invented as a sensor that compensates for these drawbacks, and has the feature of being able to simultaneously measure sound and vibration acceleration at the measurement point, and the appearance of such a device has been desired. be.

<Purpose of the Invention> The purpose of the present invention is to propose a sensor structure that combines a microphone and a vibration acceleration pickup that can simultaneously measure sound and vibration acceleration at a point to be measured, as well as sound inside a structure and vibration acceleration on the surface of the structure. shall be.

<Summary of Means> The present invention has an outer box of the device composed of an upper chamber and a lower space, a microphone for measuring sound pressure is located in the upper chamber, and a microphone for measuring vibration is located in the lower chamber. A vibration acceleration pickup is located in the lower chamber, and a communication hole for transmitting sound to the upper chamber is located in the axial center of the lower chamber.

The upper chamber has a structure in which it is partitioned into upper and lower parts by a sound pressure receiving membrane, and a back electrode is provided at the top, and the sound pressure receiving membrane and the back electrode form a condenser microphone, and the pressure in the back electrode chamber and the sound pressure propagation chamber is A pressure adjustment hole is provided to balance the pressure, and the sound pressure propagation hole provided at the center of the bottom of the sound pressure propagation chamber and the end of the communication hole provided at the center axis of the vibration acceleration pickup in the lower chamber are connected via an insulating sealing material. This paper proposes a structure for an integrated vibration/acoustic measurement sensor that is characterized by a structure in which the two sensors are in close contact with each other.

Embodiment 1 FIG. 1 is a longitudinal sectional view of a compression type device showing a first embodiment of the present invention.

The device outer box of the sensor 1 has casings 2a, 2b,
It is formed by assembling 2c. The upper chamber 3 is formed by assembling the casings 2a, 2b, and 2c. The upper chamber 3 is partitioned by a vibrating membrane 4 into an upper partition chamber 3a and a lower partition chamber 3b. A microphone back electrode is held within the upper partition 3a via vibration insulators 6a and 6b.

Pressure balance between the upper partition chamber 3a and the lower partition chamber 3b is ensured by air pressure adjustment holes 7. This air pressure adjustment hole maintains a balance between the pressure in the field to be measured and the pressure in the back electrode portion, making it possible to prevent damage to the vibrating membrane due to static pressure. Incidentally, a ventilation hole 8 is similarly provided for the vibration insulating material 6a.

On the floor of the lower partition 3b (which is also a part of the casing 2c) is a sound wave transmission nozzle 1 having a sound wave transmission passage 9 coaxial with the casing axis.
0 is located hanging downward.

The sound pressure measuring section 11 is assembled by assembling each of the above-mentioned members.
is formed.

The lower space 12 is formed by assembling the casing 2c and the pickup body 15. The vibration acceleration pickup 13 includes a pickup main body 15 having a communication hole 14 for transmitting sound waves at its axis, and a piezoelectric element 16.
and weights 17a and 17b.

The pick-up body 15 is provided with a connection tap hole 19 having the same axis as the communication hole 14, and a passage for sound wave transmission having the same axis as the communication hole at the center of the tap hole 19 that is screwed into the threaded portion 19a. A plug 22 (shown in FIG. 3) having a diameter of 22a connects and fixes the test object (not shown).

The sensor and the object to be inspected may be connected by other means as long as they properly transmit sound waves and vibrations.

A vibration insulating sealing material 20 is positioned and held between the top end surface of the pickup body and the sound wave transmission nozzle 10. Reference numeral 21 indicates a nozzle for drawing out electric wires for transmitting signals. Note that a signal transmission wire connected to the microphone can be inserted through a draw-out hole (not shown) provided in the casing 2a.

Embodiment 2 In FIG. 1, the piezoelectric element 16 is provided in a compression type, whereas in FIG. 2 of the second embodiment, the piezoelectric element 16' is provided in a shear type, and a heavy A weight 17' is provided. Other constituent members are the same as in FIG. 1.

<Effects of the Invention> The axial center of the vibration acceleration pickup 13 and the axial center of the communication hole for transmitting sound waves are the same, and this communication hole 14 opens into the lower partition chamber 3b so that sound pressure is transmitted to the vibrating membrane 4. , consists of a part that converts sound pressure into an electrical signal by changing the capacitance between the diaphragm 4 and the back electrode 5, and a vibration acceleration pickup part.By processing and evaluating each electrical signal, the sound and A comprehensive evaluation judgment can be made based on vibration. As a result, it becomes possible to reliably judge the abnormality of a mechanical device, which has conventionally been evaluated and judged only based on vibration, by using both of them.

The air pressure adjustment hole 7 is a hole provided to balance the front and rear static pressure of the microphone back electrode when the static pressure in the space to be measured is not atmospheric pressure, and it greatly contributes to the characteristics of this pick-up sound pressure measuring section. .

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a sensor according to a first embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of a sensor according to a second embodiment, and FIG. 3 is a vertical cross-sectional view of a plug connecting the sensor and an object. It is. 1...Sensor, 2a, 2b, 2c, 2d...
Casing, 3...Upper chamber, 3a...Upper partition, 3
b... Lower partition, 4... Vibration membrane, 5... Back electrode, 6
a, 6b... Vibration insulating material, 7... Air pressure adjustment hole, 8
...Vent hole, 10...Sound wave transmission nozzle, 11...
...Sound pressure measurement section, 12...Lower space, 13...Vibration acceleration pickup, 14...Communication hole, 15...
Pick-up body, 19...Tap hole for connection, 2
0... Vibration insulation sealing material, 22... Plug.

Claims (1)

[Scope of Claims] 1. The outer box of the device is formed of members constituting an upper chamber and a lower space, respectively, the upper chamber is partitioned by a vibrating membrane into an upper partition chamber and a lower partition chamber, and a microphone is located in the upper partition chamber. The outer box of the device is provided with an air pressure adjustment hole that communicates the upper partition and the lower partition, the upper partition, the lower partition, a vibrating membrane, and a microphone form a sound pressure measuring section, A vibration acceleration pick-up having a communication hole for sound wave transmission that is coaxially centered with the lower end of the sound wave transmission passage provided in the center of the bottom plate through an insulating sealing material and in contact with the upper end thereof is provided in the lower space. Features an integrated vibration/acoustic measurement sensor. 2. The vibration/acoustic measurement integrated sensor according to claim 1, wherein the microphone is a condenser microphone. 3. The vibration/acoustic measurement integrated sensor according to claim 1, wherein the microphone is a piezoelectric microphone. 4. The vibration/acoustic measurement integrated sensor according to claim 1, wherein the microphone is an electrodynamic microphone. 5. The vibration/acoustic measurement integrated sensor according to claim 1, wherein the components of the vibration acceleration pickup are a compression type piezoelectric element and a weight. 6. The vibration/acoustic measurement integrated sensor according to claim 1, wherein the constituent members of the vibration acceleration pickup are a shear type piezoelectric element and a weight.