JP2003075284A - Method for inspecting leakage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inspect leakage of a product, e.g. a compressor (2), readily and accurately by one process using simple equipments while suppressing the cost. SOLUTION: A compressor (2) is set in a sound insulation box (3) provided with sound source locating sensors (1) capable of specifying the direction of a sound source. When fluid is supplied into the compressor (2) and delivered therefrom, a delivery sound generating position is specified using a plurality of sound source locating sensors (1) and the leak position (P) of an object is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak inspection method for products, such as compressors and heat exchangers, which are required to have hermeticity.

[0002]

2. Description of the Related Art Conventionally, in a compressor manufacturing line used in, for example, an air conditioner, for example, 2
A leak inspection consisting of processes is carried out. Specifically, first, as shown in FIG. 5, a leak test using an ultrasonic sensor is performed, and then, as shown in FIG. 6, a helium / halogen leak test is performed.

As shown in FIG. 5, the ultrasonic leak inspection is carried out by setting the compressor (51), which is the object of inspection, in the soundproof box (52). Inside the soundproof box (52), for example, an ultrasonic sensor (53) is provided at each corner, and a fluid is supplied to the compressor (51). If the fluid leaks from the compressor at this time, the ultrasonic wave component contained in the leaked fluid (54) is detected by one of the ultrasonic wave sensors (53).
The compressor (51) is set in the soundproof box (52) and the inspection is performed to prevent false detection due to surrounding ultrasonic wave sources such as an air driver (not shown) used in the factory. This is to prevent it.

The compressor (51) in which fluid leakage is detected is shown in FIG.
Helium / halogen leak test for leak location
(P) is specified. In this test, the probe (5
Using a leak tester (56) with 5), move the probe (55) around the compressor (51) filled with helium gas etc. to scan the gas leak,
Identify (P).

[0005]

The above-mentioned conventional inspection method requires two steps, so that the inspection time is long and the working cost is high. In addition, the helium / halogen leak test requires high equipment costs and running costs. In addition, the helium / halogen leak test is temperature dependent, which may complicate the system and lead to inaccurate inspection.

The present invention was devised in view of the above problems, and an object thereof is to easily and accurately carry out a leak test of a product such as a compressor in one step with simple equipment. It is also necessary to keep costs down.

[0007]

According to the present invention, a sound source localization sensor (1) capable of specifying the directionality of a sound source is attached to a plurality of locations on the inner surface of a soundproof box (3) to prevent leakage of sound in a single inspection. The leak position (P) can be specified at the same time as the presence or absence is detected.

Specifically, the leakage inspection method according to the first solution provided by the present invention provides a soundproof box (3) provided with a plurality of sound source localization sensors (1) capable of specifying the direction of a sound source. When the inspection object (2) such as a compressor is set, the fluid is supplied to the inside of the inspection object (2), and when the fluid is flowing out of the inspection object (2), the ejection sound is generated. The position is specified by a plurality of sound source localization sensors (1), and the leak position (P) in the inspection object (1) is detected.

In the first solving means, the inspection is carried out as follows. First, the inspection object (2) is set inside the soundproof box (3), and a fluid such as compressed air is supplied to the inside of the inspection object (2). In this state, if the fluid leaks from the inspection object (2), a sound is generated due to the leakage. When sound is generated in this way, multiple sound source localization sensors
The directionality of the sound source is detected in (1) and these sensors
The position where the sound is generated is detected from the directionality of the sound source with respect to (1). As a result, the leak position (P) in the inspection object (2) is detected.

The second solution provided by the present invention is as follows.
In the first solution, the soundproof box (3) is a hexahedron, and the sound source localization sensors (1) are arranged in pairs on each of the six surfaces of the soundproof box (3). (1,1)
The feature is that they are placed in different directions for inspection.

The third means for solving the problems of the present invention is as follows.
In the second solving means, a set of two sound source localization sensors (1,1) provided on each surface of the soundproof box (3) is arranged along the horizontal axis and the vertical axis for inspection. It is characterized by performing.

In the second and third solving means, the soundproof box
The sound source localization sensor (1,1) provided in pairs on each of the six faces of (3) identifies the leakage position (P) in the inspection object (2). Since the directions of the sound source localization sensors (1, 1) of each set are different, the directionality of the sound source can be detected in a wide range.

A fourth means for solving the problems of the present invention is
In the first, second or third means for solving the problems, the object to be inspected is the compressor (2).

In the fourth solving means, the compressor (2) is set as an inspection object inside the soundproof box (3), and the compressor (2) is set in accordance with the methods of the first to third solving means. The leak location (P) is identified.

[0015]

According to the above-mentioned first solution, the fluid from the inspection object (2) set in the soundproof box (3) by a plurality of sound source localization sensors (1) in one inspection. It is possible to specify the leakage position (P) as well as the presence or absence of leakage. Therefore, the inspection time can be shortened and the work cost can be reduced. Moreover, since the inspection is performed only once, a plurality of inspection equipments are not required and the equipment cost can be reduced. Further, since this inspection does not depend on the temperature, the system is not complicated and the operation is not complicated.

Further, according to the second and third solving means, a set of two sound source localization sensors (1, 1) is provided on each of the six surfaces of the soundproof box (3), and the orientation of each of them is adjusted. Since the positions are changed, it is possible to accurately specify the leak position (P) in a wide range.

Further, according to the fourth solving means, it becomes possible to easily and accurately identify the position of the leak in the compressor (2).

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

First, the sound source localization sensor used in this embodiment will be described with reference to FIGS. 1 to 3.
Fig. 1 shows the layout of the sound source localization sensor (1) attached to the soundproof box (3), Fig. 2 shows the perspective view of the sound source localization sensor (1), and Fig. 3 shows the sound source localization sensor (1). It is a partially expanded view (perspective view of an acoustic sensor). 1 and 2, for convenience,
Both the contour and the internal structure are shown by solid lines.

The sound source localization sensor (1) is attached to the inner surface of a soundproof box (3) in which the compressor (2) to be inspected is set. The soundproof box (3) is a hexahedron (cube), and the sound source localization sensors (1) are arranged in pairs on each of the six surfaces of the soundproof box (3).

As shown in FIG. 2, the sound source localization sensor (1) is provided with an acoustic sensor (11) in a cylindrical casing (10). Further, as shown in FIG. 3, the acoustic sensor (11) includes a film-like diaphragm (11b) for receiving a vibration wave on the semiconductor silicon substrate (11a), and the diaphragm (1).
1b) is provided with a backbone (11c) whose one end is connected, and a plurality of cantilevers (11d) whose bases are connected to the backbone (11c).

The cantilevers 11d have the same thickness and different lengths, and have different resonance frequencies. The cantilever (11d) is dimensioned so that the diaphragm (11b) side is short and gradually becomes longer as it moves away from the diaphragm (11b). It is configured to shift to frequency.

Each cantilever (11d) is integrally formed on a semiconductor silicon substrate (11a) by using a micromachining technique together with a backbone (11c) supporting these bases. The backbone (11c) has a wide width on the diaphragm (11b) side and a narrow width on the opposite end, and the width changes continuously between them.

In this structure, the acoustic signal or the vibration wave received by the diaphragm (11b) which is the wave receiving portion is transmitted to the backbone (11c) and is frequency decomposed at the resonance frequency of each cantilever (11d). That is, when the diaphragm (11b) vibrates and the vibration propagates to the backbone (11c), the plurality of cantilevers (11d) resonate corresponding to the vibration components of their respective resonance frequencies.

Further, the vibration of the cantilever (11d) is converted into an electric signal by a piezoresistor (not shown) built in the base of the cantilever (11d) and output.
A piezoresistor is a resistance element that changes its resistance value according to the strain when the cantilever resonates due to the propagation of an acoustic signal or a vibration wave.

Casing (10) of the sound source localization sensor (1)
Has a cylindrical shape, and end plates (10a, 10b) are provided at both ends thereof. The acoustic sensor (11) is installed on the lower end plate (10a) (hereinafter referred to as the lower plate) of the casing (10) in FIG. 2, and the upper end plate (10b) (hereinafter referred to as the upper plate) in the figure. There is a circular opening (10c) in the center. Into this opening (10c), external sound is introduced directly into the casing (10) and the diaphragm (11) of the acoustic sensor (11) is introduced.
A horn (12) for guiding to b) is provided as a waveguide. Further, on the upper surface of the upper plate (10b), a reflection plate that reflects external sound and indirectly introduces it into the casing (10) and guides the indirect sound to the diaphragm (11b) of the acoustic sensor (11). (13)
Is provided.

In this way, the external sound is detected by the acoustic sensor (11).
It is introduced to the diaphragm (11b) as two kinds of sounds, a direct sound and an indirect sound. Here, when direct sound and indirect sound from one sound source are introduced to the acoustic sensor (11), sound of a specific frequency interferes with each other depending on the direction in which the sound is coming from the sound source toward the reflector (13). It has the property of being canceled (this has been published as a research paper of a mono-ear sound source localization sensor at the Institute of Electrical Engineers, etc.).

Therefore, by utilizing this, in all the directions in which the sound comes from the sound source toward the reflector (13), the direction and the frequency of the canceled sound have a 1: 1 relationship. By checking the canceled frequency, it is possible to detect from which direction the sound came. For this reason, the reflector (13) is formed in a specific shape so that the directivity of the sound and the canceled frequency have a 1: 1 relationship.
The directionality of the sound can be specified by detecting the frequency of the canceled sound. Since the leakage sound of the compressor is a sound in a certain band, the reflector (1
3) should be made.

As described above, the sound source localization sensor (1) is
A set of two is attached to each side of the soundproof box (3). Specifically, two sound source localization sensors (1) are attached to each of the six inner surfaces of the soundproof box (3), one in each set is along the horizontal plane, and one is in the vertical plane. Are arranged along. As a result, the directionality of the sound source can be accurately specified in a wide range in the vertical and horizontal directions.

FIG. 4 shows the overall configuration of a system for carrying out the leak inspection method of this embodiment. Soundproof box (3)
An amplifier (4) is connected to each of a plurality (12 in this embodiment) of sound source localization sensors (1) attached to the. These amplifiers (4) are connected to a multiplexer (5), which is a sample and hold circuit.
It is connected to the analysis computer (8) via (6) and the A / D converter (7). Thus, for each sensor (1), the output of each cantilever is switched by the multiplexer and read sequentially to obtain the vibration level for each frequency. Computer for analysis (8)
The shape data of the compressor (2) is stored in advance in
The position of the sound source (leakage position
(P)) is specified.

-Driving Operation- Next, a method for inspecting a compressor for leakage by this system will be described.

First, the compressor (2) is set in the soundproof box (3), and a fluid such as air is supplied to the compressor (2) from the air supply pipe (9). At this time, if fluid leakage occurs from the compressor (2), sound is generated from the leakage position (P). This sound is introduced into each sound source localization sensor (1).

In the sound source localization sensor (1), the acoustic signal incident on the diaphragm (51b), which is the wave receiving section, is transmitted to the backbone (51c) and is frequency-decomposed at the resonance frequency of each cantilever (51d). The vibration of the cantilever (51d) is
A piezoresistor (not shown) built in the base of the cantilever (51d) converts it into an electric signal and outputs it. This output signal is amplified by the amplifier (4), fetched by the multiplexer (54) and the sample & hold circuit (55) for each frequency band, and further, the A / D converter (5
It is converted to a digital signal in 6) and then input to the analysis computer (8).

In the analysis computer (8), the position of the sound source is specified. Specifically, direct sound and indirect sound are introduced to each sound source localization sensor (1), and the sound of a specific frequency is canceled according to the directionality of the sound from the sound source to the sound source localization sensor (1). Therefore, by detecting the frequency of the canceled sound, the directionality of the corresponding sound (direction from the sound source to the sensor (1)) is detected. Then, as shown on the display screen (8a) of FIG. 4, the position of the sound source is specified by detecting the directionality of the sound source with respect to the plurality of sound source localization sensors (1). In the example of the figure, it is shown that the position of the sound source is specified by synthesizing the sound directionality with respect to the sound source localization sensor (1) of at least three surfaces.

-Effect of Embodiment- According to this embodiment, when the fluid leaks from the compressor (2) set in the soundproof box (3), a plurality of sound source localization sensors (1) cause It is possible to identify the leak position (P) as well as the presence or absence of fluid leakage in a single inspection. Therefore, the inspection time can be shortened and the work cost can be reduced. Further, since the inspection is done only once, the inspection equipment can be simplified and the cost can be reduced. Furthermore, since this inspection does not depend on temperature, there is no need for correction, and the system is neither complicated nor complicated in operation.

Further, two sound source localization sensors are provided as a set on each of the six surfaces of the soundproof box (3), and one is arranged along the horizontal axis and the other is arranged along the vertical axis. position
It is possible to specify (P) accurately in a wide range.

[0037]

Other Embodiments of the Invention The present invention may have the following configurations in the above embodiments.

For example, in the above embodiment, two sound source localization sensors (1) are attached as a set to all six surfaces of the soundproof box (3), one on each surface is oriented vertically and one is oriented horizontally. However, the sound source localization sensor does not necessarily have to be arranged in this way. For example, when considering the six faces of the soundproof box (3) as three sets of facing faces, place the sensor (1) vertically on one of the facing faces and the sensor (1) on the other face horizontally. For example, the arrangement of the sensors may be changed.

Further, in the above embodiment, the soundproof box (3) is made up of 6
Although the soundproof box (3) does not necessarily have such a shape, it may have a shape such as another polyhedron, a cylinder, or a sphere.

[Brief description of drawings]

FIG. 1 is a layout configuration diagram in which a sound source localization sensor is attached to a soundproof box in a leakage inspection method according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of a sound source localization sensor used in the leakage inspection method of FIG.

FIG. 3 is a perspective view showing a schematic configuration of an acoustic sensor that constitutes a sound source localization sensor.

FIG. 4 is an overall configuration diagram of a system for performing a leak inspection method according to an embodiment.

FIG. 5 is a diagram showing a first step (ultrasonic test) of a conventional leak inspection method.

FIG. 6 is a diagram showing a second step (helium / halogen leak test) of the conventional leak inspection method.

[Explanation of symbols]

(1) Sound source localization sensor (2) Soundproof box (3) Soundproof box (4) Amplifier (5) Multiplexer (6) Sample hold circuit (7) A / D converter (8) Analysis computer (10) Casing (10a) Lower plate (10b) Upper plate (10c) Opening (11) Acoustic sensor (11a) Semiconductor silicon substrate (11b) diaphragm (11c) Backbone (11d) Cantilever (12) Horn (13) Reflector

Continued front page    F-term (reference) 2G064 AA11 AB16 AB22 BA03 BA08                       BA28 BD04 BD33                 2G067 AA34 CC04 DD13 EE08

Claims (4)

[Claims] 1. An object to be inspected (2) inside a soundproof box (3) equipped with a plurality of sound source localization sensors (1) capable of specifying the direction of a sound source.
To supply the fluid to the inside of the inspection object (2), and when the fluid leaks from the inspection object (2), the sound emission position is detected by multiple sound source localization sensors (1). The leak inspection method is characterized by detecting the leak position (P) in the inspection object (2) by specifying the. 2. The soundproof box (3) is a hexahedron, and the sound source localization sensors (1) are arranged in pairs on each of the six surfaces of the soundproof box (3), and the sound source localization sensor (1 , 1) are arranged in different directions to perform the inspection.
Leak inspection method described. 3. A sound source localization sensor (1,1) provided on each surface of the soundproof box (3) is arranged along a horizontal axis and a vertical axis for inspection. The leak inspection method according to claim 2. 4. The leak inspection method according to claim 1, wherein the inspection object is a compressor (2).