JPH07174660A - Method and apparatus for detection of leak part - Google Patents

Abstract

PURPOSE:To eliminate an erroneous detection due to the influence of a wind, high-speed spout of smoke, and liquefaction of the smoke and the like, and to enhance the accuracy of a smoke detection in a leak-part detection apparatus which detects the bonding defect part or the member defect part of an engine or the like whose airtightness is required. CONSTITUTION:An object 10 to be inspected is enclosed in a hermetically sealed chamber 51, the inside of the engine 10 is sucked by a first vacuum pump 47, and the inside of the hermetically sealed chamber 51 is sucked by a second vacuum PUIIIP 54. Then, on the basis of outputs from pressure sensors 50, 55, the pressure difference between the inside and the outside of the engine 10 is set so as to become definite, and fluorescent smoke which is leaked from the inside of the engine 10 is detected in this state. Thereby, a leak part is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting a leaked portion, and more particularly, a device and method for detecting a leaked portion by sending smoke into a sealed body to be inspected and detecting the leaked smoke. Regarding

[0002]

2. Description of the Related Art As an apparatus for inspecting a defective assembly such as an engine for which airtightness is required (for example, an engine) or a defective portion of a material, the following apparatus can be given.

In the apparatus disclosed in Japanese Patent Laid-Open No. 61-217734 and Japanese Patent Laid-Open No. 61-217735, a gas such as alcohol is pressed into the body to be inspected and the gas leaking from the body to be inspected is detected. By this, the leakage location is specified. Further, in the devices disclosed in JP-A-61-212741 and JP-A-63-204126, a colored gas is press-fitted into the body to be inspected, and the leaked gas is detected to detect leakage of the body to be inspected. The location is specified.

However, in the devices described in JP-A-61-217734 and JP-A-61-217735, a colorless gas such as alcohol is used as a medium, so that the leakage can be detected. A special sensor is required, and the entire surface of the object to be inspected must be thoroughly inspected by the sensor at the time of inspection. Especially, when the object to be inspected is large, there is a problem that it takes a lot of time and labor. there were. Further, in the devices described in JP-A-61-212741 and JP-A-63-204126, a visual inspection is carried out using a colored gas. Since it is small, there is a problem that it is difficult to detect a minute amount of leakage due to diffusion into the atmosphere.

Therefore, the present applicant has filed Japanese Patent Application Laid-Open No. 4-24221.
No. 34 proposes a leak location detecting device.

FIG. 6 is a diagram showing the apparatus, in which the engine 10 is an object to be inspected. The fluorescent smoke generator 13 connected to the compressor 11 generates fluorescent smoke 17 containing a fluorescent substance, and the fluorescent smoke 17 is sent to the engine 10. On the other hand, a plurality of ultraviolet lamps 16 for irradiating the entire engine 10 are arranged around the engine 10.

In detecting the leaked portion of the engine 10, first, at least one pressure inlet is left, and the other opening of the device under test 10 is closed. Then, prior to the smoke filling, a vacuum pump 25 is first set to make the inside of the inspected body negative pressure.
Is activated and the air in the device under test 10 is discharged to the outside.
Here, the inspection object 10 is housed in the dark room 15.
After that, the switching valve 26 is switched so that the inspection object 1
0 and the fluorescent smoke generating device 13 are connected. Here, the fluorescent smoke generator 13 is connected to the compressor 11,
Furthermore, since the fluorescent smoke generating device 13 and the compressor 11 operate simultaneously, the fluorescent smoke generated by the fluorescent smoke generating device 13 is pressed into the inspected object 10 by the compressor 11. Here, when there is a leaked portion on the inspection object 10, the fluorescent smoke containing the fluorescent substance leaks out from the leaked portion to the outside. Then, if it is irradiated with the ultraviolet lamp 16, the fluorescent smoke leaked to the outside emits light,
It is possible to detect the leaked portion of the device under test 10. At this time, the object to be inspected 10 is housed in the dark room 15, so that the detection is easy. After the inspection, the air cleaner 27 removes the fluorescent smoke leaking into the dark room 15 in preparation for the next inspection.

Here, the ultraviolet lamp 16 irradiates the fluorescent smoke leaking from the leaked portion of the object 10 to be inspected,
The fluorescent component in the fluorescent smoke emits light, but the means for detecting the emission of this fluorescent component is not limited to visual observation, and is detected using a photodetector such as an image captured by a TV camera and determined by image processing. Of course, it is also possible.

In this way, the above-mentioned JP-A-4-2421
In the device described in No. 34, since this uses fluorescent light emission, the light emission can be clearly recognized, and the leaked portion can be detected more sensitively and easily than in the conventional case.

[0010]

However, in the apparatus disclosed in the above-mentioned Japanese Patent Laid-Open No. 4-242134,
Since the inside of the body to be inspected has a high pressure, there is a problem that the fluorescent smoke aggregates and returns to the liquid in the body to be inspected. Further, since the pressure inside the object to be inspected is high, the ejection speed of the smoke leaking from the defective portion is high, which causes a problem that the smoke density becomes small and it is difficult to see. Further, there is a problem that an error occurs in the detection of the leaked portion due to a disturbance such as wind generated in the dark room.

The present invention has been made in view of the above problems, and an object thereof is a leakage location detecting device which is not affected by disturbance and at the same time does not cause smoke agglomeration or a decrease in density of leaking smoke. And to provide a method.

[0012]

In order to solve the above-mentioned problems, in the method for detecting a leaked part according to the present invention,
A method of sending smoke sensitive to detection light into a sealed body to be inspected, and detecting the leaked portion of the body to be inspected from the leaked smoke, wherein the smoke sensitive to the detection light is fed into the body to be inspected. Injecting step, depressurizing the outside of the inspected object into which the smoke is sent, and setting a predetermined pressure difference inside and outside of the inspected object, and in a state where a predetermined pressure difference is set inside and outside An irradiation step of irradiating the inspection object with detection light, a detection step of detecting the presence or absence of smoke sensitive to the detection light in the outer shell of the inspection object, and a detection light in the outer shell of the inspection object. When smoke that is sensitive to is detected, a specifying step of specifying a leak point by specifying a jet position of the smoke is included.

Further, in the leak point detecting device according to the present invention, smoke sensitive to the detection light is sent into the sealed inspected body, and the leaked portion of the inspected body is detected from the leaked smoke. There, a sealed chamber for accommodating the inspection object, a smoke supply device for sending smoke sensitive to the detection light into the inspection object, a first pressure control device for controlling the pressure in the inspection object, and A second pressure control device for controlling the pressure in the closed chamber, a differential pressure setting device for controlling the first and second pressure control devices to set a predetermined pressure difference inside and outside the inspected body, and A lamp that irradiates the inspection object with detection light, and a detection device that detects a leaked portion by specifying the position of the smoke that is sensitive to the detection light of the lamp,
It is characterized by including.

[0014]

In the method for detecting a leaked portion according to the present invention having the above-mentioned structure, when a predetermined pressure difference is set after smoke is sent into the body to be inspected, the pressure difference in the body to be inspected is accompanied by the pressure difference. Smoke leaks from. The leaked smoke is
It is irradiated with the detection light and responds to it. Here, if there is a leak location on the inspected object and smoke is leaking, the presence of smoke that is sensitive to the detection light is detected, and then the location where the smoke is ejected is specified to determine the location of the leak location. Identification is done.

Further, in the leak location detecting device according to the present invention, after the object to be inspected is housed in the closed chamber, smoke is sent into the object to be inspected by the smoke supply device, and the object to be inspected is filled with smoke. It Then, in this state, the differential pressure setting device controls the first and second pressure control devices to generate a predetermined pressure difference between the inside and the outside of the inspection object. On the other hand, the lamp irradiates the entire inspection object.

Here, if there is a leak location in the inspected body, smoke will leak from the inspected body based on the pressure difference set by the differential pressure setting device. The leaked smoke is sensitive to the detection light of the lamp, and this is detected by the detection device, and the ejection position is specified to detect the leakage portion. That is, by detecting the position where the smoke is ejected as the leak point, the leak point is detected.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a leak location detecting device according to a preferred embodiment of the present invention. In the figure, the same components as those in the conventional example are designated by the same reference numerals.

The engine 10 shown in FIG. 1 is an object to be inspected, which is inspected for improper assembly, material defects, hermeticity of the oil seal portion, and the like. Here, at least one opening of the engine 10 is used as a smoke inlet and the other opening is connected to a vacuum pump. The other openings are sealed to ensure the airtightness of the engine 10.

The leak location detecting apparatus according to the present embodiment has a smoke producing device 13 for producing fluorescent smoke, as in the prior art, and from this smoke producing device 13, the engine 1 which is an object to be inspected.
0 Fluorescent smoke is supplied to the inside. A solenoid valve 45 is attached to the inlet pipe 44 connected to the engine 10 so as to control the sending and stopping of the fluorescent smoke. On the other hand, a first vacuum pump 47 is connected to the engine 10 via an outlet pipe 46. Therefore, by driving the first vacuum pump 47, the inside of the engine 10 is deaerated. In addition, the outlet pipe 46 has a first
The pressure regulator 48 is attached, and the suction force of the vacuum pump 47 is controlled by the pressure regulator 48. Here, the pressure regulator 48 is adapted to be controlled by the first pressure control device 49, and the control of the pressure control device 49 is performed by the first pressure sensor 50 that detects the pressure in the outlet pipe 46. Based on the output of.

In this embodiment, a closed chamber 51 for accommodating the engine 10 to be inspected is provided.
A second vacuum pump 54 is connected to the via a suction pipe 53. The pressure inside the closed chamber 51 is detected by the second pressure sensor 55. In addition,
A seal 56 is provided at a place where each pipe penetrates in the closed chamber 51 to keep airtightness. Further, a second pressure regulator 57 is attached to the suction pipe 53,
With this, the suction force of the vacuum pump 54 is adjusted. Here, the second pressure regulator 57 is controlled by the second pressure controller 58, and the second pressure controller 58 is controlled.
Controls the second pressure adjuster 57 according to the outputs of the first pressure sensor 50 and the second pressure sensor 55. That is, in the present embodiment, the second pressure control device 58 inputs the outputs of the two pressure sensors, and the pressure inside the closed chamber 51 is kept so that the pressure outside the engine 10 is always lower than the internal pressure by a predetermined amount. Control the internal pressure.

Next, the operation of the leak point detecting apparatus according to this embodiment will be described with reference to the flow chart of FIG.

When detecting a leaked portion, first, the engine 10 which is the object to be inspected is hermetically sealed except for the connecting portion of the inlet pipe 44 and the outlet pipe 46. After that, the solenoid valve 45 is closed (S101)
Then, the smoke generator 13 is activated to produce fluorescent smoke (S
102). On the other hand, the vacuum pump 47 is operated with the solenoid valve 45 closed (S103), and the sealed engine 10 is evacuated. When the solenoid valve 45 is opened after the evacuation is performed (S
104), the fluorescent smoke produced by the smoke generator 13 flows into the engine 10, and the sealed air inside the engine 10 is replaced with the fluorescent smoke.

Here, it is confirmed whether or not the inside of the engine 10 is completely replaced with fluorescent smoke, that is, whether or not the smoke inflow is completely performed (S105), and if the complete smoke inflow is confirmed, the solenoid valve is checked. 45 is closed (S106).

In the state of S106, the outside and inside of the engine 10 are at normal pressure, and there is no pressure difference between the inside and the outside.
However, in the present embodiment, thereafter, the second vacuum pump 54 is operated to perform suction in the closed chamber 51 (S10).
7). When such suction is performed, the atmospheric pressure outside the engine 10 becomes low, and a pressure difference occurs between the inside and the outside. In the embodiment, this pressure difference is 294 Pa (3
cmAq) is set (S108). Then, the fluorescent smoke is detected in the state where the pressure difference is 294 Pa (3 cmAq) (S109).

If the inflow of smoke is not completed at S105, the solenoid valve 4 is restarted.
A vacuum is drawn with 5 closed so that the inside of the engine 10 is completely exhausted. Further, in S108, the pressure difference between the inside and the outside of the engine 10 is a predetermined value (294 in the embodiment).
If it does not become Pa), the second vacuum pump 54
To set the pressure difference to this value.

FIG. 3 is a graph showing changes in pressure inside and outside the engine 10. In this figure, the solid line indicates the device under test 10.
The internal pressure is shown, and the broken line shows the external pressure. This Figure 3
As shown in (1), vacuuming is performed by the first vacuum pump 47 at t ₁ , which causes the pressure inside the engine 10 to rapidly decrease. After that, when the solenoid valve 45 is opened and the fluorescent smoke is introduced, the internal pressure of the engine 10 suddenly returns to the normal pressure. Next, when suction is performed by the second vacuum pump 54 at t ₃ , the pressure inside the closed chamber 51 (that is, outside the engine 10) decreases. Here, if there is a leak portion in the engine 10, gas leaks from the leak portion, so that the internal pressure of the engine 10 also decreases. in this case,
In this embodiment, the feedback control is performed so that the pressure difference between the inside and the outside of the engine 10 becomes a predetermined value.
The pressure inside the sealed chamber 51 also decreases following the decrease in the internal pressure of the engine 10, and as a result, fluorescent smoke is ejected from the engine 10 while the pressure difference between the inside and outside of the engine 10 is kept constant. . For this reason, the fluorescent smoke is not ejected at high speed, and the fluorescent smoke is not diluted. Therefore, in the leak location detecting device according to the present embodiment, the density of the leaking fluorescent smoke can be kept high, which facilitates the detection. Further, since the fluorescent smoke is not press-fitted into the engine 10, the fluorescent smoke does not aggregate and vaporize inside the engine 10.

Incidentally, as shown in FIG.
If the inside of the engine 10 is sucked and the gas leaks from the leaked place, and the fluorescent smoke is supplied by the amount of the decrease in the internal pressure of the engine 10, the internal pressure of the engine 10 can be maintained constant. It is possible to do it. In this case, the opening / closing of the solenoid valve 45 may be feedback-controlled.

In order to detect the leaked smoke and identify the leaked portion, for example, as in the conventional example shown in FIG. 6, a method of irradiating the entire engine 10 with an ultraviolet lamp 16 and visually observing the same is adopted. Of course you can. However, in order to easily and surely detect the leaked smoke, the following method using slit light can be used.

According to the method of identifying a leaked portion using this slit light, the slit light 32 is irradiated along the detection surface of the engine 10 and is directed in a direction orthogonal to the irradiation direction of the slit light 32 (slit light surface). TV camera 4 placed
Leaked smoke is detected by shooting with No. 1 and the leaked portion is specified from the image displayed on the CRT 43 shot by the television camera 41 (FIG. 5). As shown in FIG. 5, when the engine 10 has a leak point, smoke leaking from the leak point reaches the slit light 32, and the smoke is sensitive to the slit light 32. As a result, in the screen of the CRT 43. The fluorescence corresponding to the location of the leaked smoke is displayed on. Therefore, the observer can easily specify the presence or absence of the defect of the engine 10 and the position thereof by searching for the fluorescent spot on the screen of the CRT 43. In this case, since the slit light irradiating unit 33 irradiates only a very limited portion while avoiding the inspection object itself, it is not affected by the reflected light from the background and other structures of the engine 10. , The leakage location of the engine 10 can be specified. In particular, in the leakage point detection device according to the present invention, smoke does not eject at high speed,
Since it leaks as if it stays in the leaked area, the smoke density is high, and the brightness of the bright spots is increased accordingly.
Easy to detect. Therefore, omission of detection can be prevented, and detection accuracy can be improved.

Although there are at least six detection surfaces in the engine 10, slit light irradiation is performed on the left and right side surfaces, the upper surface side, the entire surface side, and the rear surface side, except for the bottom surface side in contact with a mounting table (not shown). Done. For the bottom side,
The direction of placement of the engine 10 is changed to irradiate the slit light to detect all the surfaces of the engine 10.

The combination of the detection light and the smoke sensitive to the detection light includes, for example, (i) a combination of ultraviolet rays and fluorescent smoke containing a fluorescent component, and (ii) a combination of laser light and scattered smoke containing particles (so-called aerosol). , Or (ii
i) A combination of white light and colored smoke containing colored components, and the like are possible. Hereinafter, the case where each of these is combined will be described.

In the above combination (i), when the fluorescent smoke is pressure-fed from the smoke press-fitting portion (inlet) 31 into the sealed engine 10, the fluorescent smoke containing the fluorescent component is produced by the smoke generator 37, and the slit is formed. Ultraviolet slit light is emitted from the light emitting unit 33. When the engine 10 has a leak point, the fluorescent smoke leaking from the leak point reaches the slit light of the ultraviolet rays, and fluorescence is emitted at that position. Therefore, in S104,
By searching for the location of fluorescence emission in the screen of the CRT 43, the location of leakage of the engine 10 can be detected. In this case, electromagnetic waves other than ultraviolet rays such as white light can be used as the detection light, but irradiation with ultraviolet rays has the advantage that the fluorescence intensity is stronger and the ultraviolet rays are invisible, so that the search is easier.

In the case of the combination of the above (ii), that is, when the laser light is used as the slit light of the detection light and the scattered smoke made of a gas containing fine particles such as aerosol is used as the smoke sensitive to the detection light, the smoke generating device is used. At 37, aerosol (scattered smoke) is produced, and the laser light is emitted as slit light from the slit light emitting section 33. In this case, since the laser light is not visible from the side, the CRT 43
Although it is not displayed on the screen of, when the laser light is irradiated on the aerosol, the laser light scatters and becomes visible from the side. Therefore, when there is a leaked portion in the engine 10, the laser light scattered by the aerosol leaking from the leaked portion appears in the screen of the CRT 43. By detecting this, the leaked portion of the engine 10 is detected. Can be easily detected.

Further, in the case of the combination of (iii), that is, when white light is used as the slit light of the detection light and colored smoke containing a colored component is used as the smoke sensitive to the detection light, the smoke generation device 37 Colored smoke is produced, and the slit light irradiation unit 33 emits white light slit light. The colored component in the colored smoke absorbs its complementary color from the white light to generate a color. When the engine 10 has a leaked spot, the colored smoke leaking from this leaked spot is colored, and this color appears on the screen of the CRT 43. By detecting this, the leaked spot of the engine 10 can be detected. It can be easily detected.

In each of the above cases, since the slit light of the detection light is emitted along the detection surface of the engine 10, the reflected light from the background and other structures of the engine 10 is emitted. The leak location of the engine 10 can be detected without being affected by. Further, the aerosol generation device and the colored smoke generation device can be made in the same configuration as the fluorescent smoke generation device.

[0037]

As described above, according to the leakage spot detecting apparatus of the present invention, since smoke is not pressed in, it is possible to prevent the smoke from condensing (liquefying) in the body to be inspected. At the same time, since the smoke is not pressed in gently, the smoke comes out gently from the leak point, so the density of the leak smoke increases, and the leak point can be detected for any type of inspected object. You will be able to do it easily. Further, omission of detection can be prevented, and detection accuracy can be improved.

Furthermore, since the object to be inspected is enclosed in a closed chamber, it is possible to detect the leaked portion without being affected by wind and the like, and the detection accuracy is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a leak location detecting device according to a preferred embodiment of the present invention.

FIG. 2 is a flow chart showing the operation of the leak point detection device according to the preferred embodiment of the present invention.

FIG. 3 is a diagram for explaining a detection operation of the leakage point detection device according to the present embodiment.

FIG. 4 is a diagram for explaining another detection operation of the leaked part detection apparatus according to the present embodiment.

FIG. 5 is a diagram showing a configuration of a leak point detection device according to the present embodiment, and is a diagram for explaining specifications of a television camera used for specifying a jetting position of fluorescent smoke.

FIG. 6 is a diagram showing a configuration of a leak point detecting device described in Japanese Patent Laid-Open No. 4-242134.

[Explanation of symbols]

 10 Engine (Inspection Object) 11 Compressor 13 Smoke Generator 16 Ultraviolet Lamp 17 Fluorescent Smoke 25 Vacuum Pump 26 Switching Valve 31 Smoke Inlet 32 Slit Light 33 Slit Light Irradiator 35 Smoke Detector 37 Smoke Generator 39 Smoke Control Device 41 Television camera 43 CRT 44 Inlet pipe 45 Solenoid valve 46 Outlet pipe 47 First vacuum pump 48 First pressure regulator 49 First pressure control device 50 First pressure sensor 51 Closed chamber 53 Suction pipe 54 Second vacuum Pump 55 Second pressure sensor 56 Seal 57 Second pressure regulator 58 Second pressure control device

Claims (2)

[Claims] 1. A method of sending smoke, which is sensitive to detection light, into a sealed body to be inspected, and detecting a leaked portion of the body to be inspected from the leaked smoke, the method being sensitive to the detection light in the body to be inspected. And a decompression step of decompressing the outside of the object to be inspected into which the smoke has been sent and setting a predetermined pressure difference between the inside and outside of the object to be inspected, and a predetermined pressure difference between the inside and the outside. An irradiation step of irradiating the inspection object with detection light in a set state, a detection step of detecting the presence or absence of smoke sensitive to this detection light in the outer shell of the inspection object, and the inspection object When smoke that is sensitive to the detected light is detected in the outer shell, a leak location detection method that includes the step of identifying the leak location by identifying the position where the smoke is ejected. 2. A device for sending smoke sensitive to detection light into a sealed body to be inspected and detecting a leaked portion of the body to be inspected from the leaked smoke, the enclosure containing the body to be inspected. Chamber, a smoke supply device for sending smoke sensitive to the detection light into the inspected body, a first pressure control device for controlling the pressure in the inspected body, and a second pressure for controlling the pressure in the closed chamber. A control device, a differential pressure setting device that controls the first and second pressure control devices to set a predetermined pressure difference inside and outside the inspected body, and a lamp that irradiates the inspected body with detection light. A detection device for detecting a leak location by specifying the position of the smoke ejected that is sensitive to the detection light of this lamp, and a leak location detection device including: