JPH0772032A - Detection of leak spot - Google Patents

Abstract

PURPOSE:To achieve higher reliability of inspection avoiding erroneous detection caused by positioning errors or the like of an object to be inspected by radiating slit light in the state being filled with no smoke, which does not allow smoke to leak, before and after a main inspection to inspect the scattering of light. CONSTITUTION:Smoke of oil particles generated by a smoke generator 14 is introduced into an engine 10 to be inspected to be irradiated with surface-shaped slit light 24 from a slit light radiator 26 and is taken picture by a camera 28. Here, when smoke is leaked at a damaged part of the engine 10 or when a partial surface of the engine 10 is irradiated with the light 24 because of positioning errors or the like, the light 24 is scattered. When the scattering occurs, to distinguish between the leakage of smoke or erroneous detection, the engine 10 filled with smoke is evacuated to be the state filled with no smoke, which does not allow the smoke to leak. The irradiation with the light 24 is performed again, and it is estimated to be the scattering due to positioning errors when the scattering of the light 24 occurs. When no scattering occurs, the engine 10 is filled with smoke again and the irradiation with the light 24 is performed to inspect the presence or absence of the scattering to obtain a correct judgement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a leaked portion, and more particularly to a method for detecting a leaked portion by filling a smoke in an object to be inspected and detecting the leaked smoke.

[0002]

2. Description of the Related Art Leakage location detection using smoke is performed in order to inspect for defective parts joining, member defects, etc. in an object to be inspected such as an engine that requires airtightness.

In the conventional leak location detecting device disclosed in Japanese Patent Laid-Open No. 4-242134, after the fluorescent smoke containing a fluorescent substance is filled in the body to be inspected, ultraviolet rays as detection light are emitted to the body to be inspected. The lamp is illuminated. At that time, if the above-mentioned defect exists, fluorescent smoke leaks from the location,
Fluorescence is emitted with respect to the detection light. Therefore, the light emission is detected and the leaked portion is indirectly detected.

Other conventional leakage location detecting devices or methods are disclosed in Japanese Patent Laid-Open Nos. 61-217734, 61-217735 and 61-212741.
And those described in JP-A-63-204126.

[0005]

However, in the conventional leak point detection, since the detection light is radiated to the entire inspected object, the inspected object itself and the background illuminate due to the irradiation, resulting in erroneous detection. Therefore, the detection accuracy could not be improved.

[0006] Therefore, the inventor of the present invention, the Japanese Patent Application No. 4-2381
No. 84, etc., proposes a leak location detecting method using slit light as the detection light. That is, the slit light is irradiated to the vicinity of the object to be inspected and the leaked smoke flowing out from the leaked portion is detected. According to this method, the slit light is emitted without touching the object to be inspected, and thus is emitted only within a limited range, so erroneous detection can be avoided.

However, in the leakage smoke detection method using such slit light, when there is a positioning error in the inspection object or the like, the inspection object touches the slit light or crosses the slit light, and the inspection object is inspected. As a result of the slit light being scattered on the surface of the body and the portion shining, there is a possibility that erroneous detection may be caused in the same manner as above. By the way, in the case of visual inspection, it is not impossible to distinguish whether or not erroneous detection is made by artificial judgment, but in the case of automatic inspection using image processing, erroneous detection cannot be avoided.

Of course, it is desired to eliminate the positioning error itself. However, for example, when inspecting an engine or the like, there are many errors such as the positioning error of the pallet itself on which the engine is mounted and the positioning error of the engine on the pallet. There are factors, and improving the positioning accuracy of the engine has certain limits due to mechanical restrictions.

Therefore, there has been a demand for a method capable of avoiding erroneous detection by automatically determining the state when a part of the object to be inspected shines due to irradiation.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a method for detecting a leaked portion which can judge only the scattering of slit light due to leaked smoke and eliminate erroneous detection.

[0011]

In order to achieve the above object, the present invention irradiates slit light in the vicinity of an object to be inspected in a filled state in which smoke is filled in the object to scatter the slit light. A main inspection step for inspecting the presence or absence, and a step provided before or after the main inspection step, irradiating the slit light in the vicinity of the object to be inspected in a non-filled state that does not cause leakage smoke and scattering of the slit light And a determination step of determining whether or not there is actually smoke leakage according to the inspection result of the main inspection step and the inspection result of the confirmation inspection step. To do.

[0012]

According to the above construction, in the main inspection process, smoke is leaked into the object to be inspected and the leakage smoke is inspected as in the conventional case. That is, the smoke is sent into the body to be inspected and filled with the smoke, and in that state, the slit light is irradiated in the vicinity of the body to be inspected. In that case, if there is a leak location, leak smoke is generated, and when the leak smoke crosses the slit light, the smoke particles cause scattering of the slit light.

However, in the scattering detected in the main inspection process, in addition to the scattering due to the presence of the above-mentioned leakage smoke, there is a possibility of unnecessary scattering on the surface of the object to be inspected due to the positioning error described above. I can't deny it.

Therefore, in the confirmation and inspection process, the slit light is irradiated in a non-filled state that does not cause leakage smoke. This is based on the fact that when the slit light is scattered even though there is no leaked smoke, unnecessary scattering on the surface of the object to be inspected is considered.

Then, in the judgment step, from the above principle,
According to the inspection results of the main inspection process and the confirmation inspection process, it is determined whether or not there is actually smoke leakage.

The confirmation inspection process can be executed after the main inspection process or before the main inspection process. Further, it is possible to provide a reconfirmation step in which smoke is filled again for inspection, a reconfirmation step in which decompression is performed after that, and the like, and the like, which can be determined according to the inspection time and required inspection accuracy. desirable. By the way, if a plurality of inspections by filling / unfilling are repeated, scattering due to leaked smoke repeatedly occurs, and the degree of identification is improved due to the intermittent scattering, and consequently the detection accuracy for weak scattering can be improved. In any case, in order to improve the detection accuracy as compared with the conventional one, one or more confirmation inspection steps are required.

As is clear from the above-mentioned principle, the non-filled state includes not only the state in which smoke does not exist in the body to be inspected, but also the depressurized state in which smoke does not leak even if there is a leak portion.

[0018]

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

FIG. 1 shows the overall configuration of a leak location detecting apparatus to which the leak location detecting method according to the present invention is applied.

In FIG. 1, an engine 10 is an object to be inspected for defective assembly, defective members and the like. A smoke generating device 14 that generates smoke is connected to the engine 10 via a pipe 12, and a smoke amount control that controls the compressor 16 that introduces air and the amount of smoke that is generated is connected to the smoke generating device 14. The device 18 is connected.

In the engine 10, all openings other than the opening to which the pipe 12 is connected are closed to form an airtight state. In the middle of the pipe 12, a switching valve 20
Is provided, and a vacuum pump 22 for evacuating the inside of the object to be inspected as a pre-process of the smoke filling process is connected to the branch passage.

On the other hand, in the vicinity of the engine 10 to be inspected,
That is, the planar slit light 24 generated by the slit light irradiating device 26 is irradiated to a position parallel to the inspection surface of the engine and separated from the inspection surface by a predetermined distance. In addition,
Although only one slit light is shown in FIG. 1, it is also possible to irradiate a plurality of inspection surfaces with slit light and simultaneously detect leaked smoke over the entire engine 10.

In the direction orthogonal to the plane of the slit light,
A camera 28 is arranged to capture the scattering of the slit light when the leaked smoke crosses, the output signal thereof is output to the image processing device 30 that specifies the presence and the position of the scattering, and the processing result is displayed on the display 32. To be done.

In FIG. 1, a control unit 34 controls the entire apparatus and is connected to each component via a signal line. First inspection step and second step, which will be described in detail later
The inspection process and the third inspection process are executed under the control of the control unit 34. The control unit 34 has a determination circuit 38, and this determination circuit determines the presence or absence of leakage which is theoretically derived from the inspection result in each inspection process. The opening / closing of the valve 20 is controlled by the control unit 34 via the switch 36.

In the case of detecting the leaked portion by the apparatus described above, first, the engine as the inspection object is sealed and the pipe 12 is connected, and then the leaked portion detecting step shown in FIG. 2 is executed. It

In FIG. 2, this series of steps includes a first inspection step (S101), a second inspection step (S102), a third inspection step (S103), and a determination step (S104-1), as shown in the figure. , S104-2).

The first inspection step (S101) is a step of detecting leaked smoke as in the conventional case. First, in S201, the injection of smoke into the engine 10 (filling) is started. More specifically, first, the valve 20 is switched to the vacuum pump 22 side to operate the vacuum pump, and the inside of the engine 10 is made a negative pressure. This is because the smoke is smoothly filled at a low pressure. After the negative pressure state is formed, the valve 20 is switched and the smoke consisting of the oil particles generated in the smoke generating device 14 is introduced into the engine 10 together with the air from the compressor 16 until it reaches a constant filling pressure. Continued. In S202, the elapse of the set time until the predetermined filling pressure is measured.

Then, in S203, the slit light 24 is applied to the vicinity of the engine 10. At that time, if there is a leaked portion such as a defective portion or a defective portion, the smoke leaks out. Therefore, when the leaked smoke crosses the slit light 24, the slit light 24 is scattered at the crossing point by the action of smoke particles. On the other hand, due to the above-mentioned positioning error and the like, the slit light 24
When a part of the outer surface of the engine 10 is irradiated with, the scattering occurs on the surface of the engine 10.

The presence or absence of such scattering is determined in S204. Specifically, by performing binarization processing on the captured image and extracting points that are bright due to scattering, the presence or absence and the position thereof can be calculated.

In the first inspection step (S101),
If it is determined that the scattering has not occurred, it is considered that there is no leakage smoke and erroneous detection, and the determination of "no leakage" is made in S213 (see FIG. 3).

On the other hand, if it is determined in the first inspection step (S101) that scattering has occurred, it is necessary to distinguish between leaked smoke and erroneous detection, so the second inspection step (S102) is performed. Done.

In this step, in S205, in order to remove the smoke from the inside of the engine 10 which is filled with the smoke, the depressurization of the engine 10 is started by activating the vacuum pump 22 or the like. Then, in S206, the pressure reduction is performed until a certain set time elapses, and the pressure is reduced to a certain pressure. The pressure reduction (exhaust) is preferably performed until the smoke completely disappears, but in order to realize a quick inspection, the internal pressure of the engine 10 can be reduced to such an extent that the leaked smoke does not substantially leak from the leaked portion. Is enough. In any case, in S206, a non-filled state in which no leakage smoke is generated is formed.

Then, in S207, the slit light 24 is irradiated again and the presence or absence of scattering is detected. Here, if there is scattering, it is presumed that the slit light is scattered on a partial surface of the engine 10 due to a positioning error or the like. On the other hand, if there is no scattering, it can be seen that there is no scattering on a part of the surface of the engine 10, that is, a normal state.

If there is scattering in S208, S213
Then, "erroneous detection" is determined (see FIG. 3). That is, the scattering occurs in both the smoke filled state and the non-filled state. In the image processing by the image processing device 30, the position of the scattering point is also calculated and specified, and when there are a plurality of scattering points, the determination shown in FIG. 3 is made for each.

On the other hand, if it is determined in S208 that there is no scattering, in the present embodiment, the third inspection step (S103) is executed to obtain a more accurate determination.

In the third inspection process, first, S209 and S
At 210, the smoke is pressed again (filled). Then, in S211, the slit light 24 is irradiated, and S212
The presence or absence of scattering is determined by. Here, if there is scattering, it is reconfirmed that scattering is caused by leaked smoke,
In S214, it is determined that there is a leak.

On the other hand, when the scattering does not occur, there is a mismatch in the inspection result, so that "a trouble has occurred" is determined. The trouble was that the leaked smoke from the previous leak location detection remained and caused scattering in the next first inspection step, but it was diffused by the third inspection step, and in the third inspection step, If there is no scattering, or if the engine position changes during inspection, etc.
An unexpected situation is expected to occur.

Therefore, the decision circuit 34 makes a decision according to the decision table of FIG. 3 based on the above inference. When it is determined that “a trouble has occurred”, it is desirable to perform each step shown in FIG. 2 again after performing visual confirmation by the device administrator.

After the process shown in FIG. 2 is completed, the inspection of the other inspection surfaces of the engine is executed, and when there is no uninspected surface, the smoke is completely exhausted and the entire inspection process is completed.

In the above embodiment, the slit light irradiation is performed in the second inspection step without producing the leaked smoke, so that the erroneous detection or the like can be judged by such a confirmation inspection step. Further, since the third inspection step is provided, the presence of residual smoke, the occurrence of trouble, etc. can be determined, and the determination result can be made more reliable.

The second inspection process can be performed before the first inspection process. Further, the inspection result can be made more reliable by repeating the above inspection process. In that case, since the scattered light to be observed blinks intermittently, there is also an advantage that the detection accuracy for a small amount of leaked smoke can be improved.

[0042]

As described above, according to the present invention,
In addition to the main inspection process, a confirmation inspection process is provided, so
It is possible to avoid erroneous detection due to a positioning error of the object to be inspected and improve the reliability of the inspection.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a leakage location detection device to which a leakage location detection method according to the present invention is applied.

FIG. 2 is a process drawing showing each process of the leakage point detection method according to the present invention.

FIG. 3 is an explanatory diagram showing a determination table of the determination circuit shown in FIG.

[Explanation of symbols]

 10 Engine (Inspected Object) 24 Slit Light 34 Control Section S101 First Inspection Step (Main Inspection Step) S102 Second Inspection Step (Confirmation Inspection Step) S103 Third Inspection Step (Reconfirmation Inspection Step)

Claims (1)

[Claims] 1. A method of detecting a leaked portion by detecting scattering of slit light with respect to leaked smoke from an inspected body filled with smoke, which is a filling state in which the inspected body is filled with smoke. In irradiating the slit light in the vicinity of the object to be inspected, a main inspection step of inspecting the presence or absence of scattering of the slit light, and a step provided before or after the main inspection step,
A confirmation inspection step of irradiating the slit light in the vicinity of the object to be inspected in a non-filled state that does not cause leaked smoke, and inspecting the presence or absence of scattering of the slit light, an inspection result of the main inspection step, and the confirmation inspection step. A method of detecting a leaked portion, comprising: a determination step of determining whether there is actually smoke leakage according to the inspection result in 1.