JP3598320B2 - Leak inspection device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a leak inspection device for inspecting whether or not a leak amount of a container is equal to or less than a standard value.
[0002]
[Prior art]
Today, parts are sometimes sealed in containers to improve the reliability of the parts. In this case, the reliability cannot be improved if the container leaks even if the parts are sealed in the container, and it is necessary to inspect the leak of the container.
[0003]
In addition, vehicles and the like are equipped with air conditioning equipment, and if there is a leak in these devices, a gas leak occurs. Therefore, it is necessary to inspect whether the leak amount is within a specified value.
The inventor of the present application has previously devised and filed in Japanese Patent Application Nos. 2000-47501 and 2000-47503 a leak inspection apparatus capable of accurately performing a leak inspection with a simple apparatus configuration.
[0004]
In the above-mentioned application, an inspection object in which input / output holes and the like are sealed is housed in a chamber, air in the chamber is exhausted, and air at atmospheric pressure filling the inspection object leaks and is discharged into the chamber. As a result, the exhaust pressure in the chamber changes, and a leak inspection of the inspection object is performed based on the change in the exhaust pressure.
[0005]
[Problems to be solved by the invention]
However, in the leak inspection apparatus of the above application, when the amount of leak from the inspection object is small, the change in the exhaust pressure in the chamber due to the leak is small, and the time until the change can be detected accurately becomes long, and the inspection time becomes long. It took time.
[0006]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a leak inspection apparatus that can accurately perform a leak inspection in a short time.
[0007]
[Means for Solving the Problems]
Means adopted by the present invention to solve the above-described problem will be described.
In the present invention, a chamber for accommodating an inspection object in which input / output holes are sealed, a pressure gauge for measuring a vacuum pressure in the chamber, and a first valve provided between the pressure gauge and the chamber A determination pressure recording unit that records a determination pressure, a time measurement unit that measures a predetermined time, a pressurization unit that pressurizes the test object housed in the chamber, an exhaust pump, and exhaust by the exhaust pump. And a second valve and a third valve respectively provided between the exhaust pump, the chamber and the tank, and closing the second valve between the chamber and the chamber prior to a leak test. open the third valve between the tank and evacuating the tank to a predetermined pressure by the exhaust pump, the first between the pressure of the tank was evacuated to a said predetermined pressure of said tank Valve maintains close and pressurize housed in the from the pressing at the time of the leak testing chamber within the inspected object at a predetermined pressure, when said pressurized to a predetermined pressure the second and third Open the valve to exhaust the air in the chamber into the tank and start timekeeping in the timekeeping unit, and when the predetermined time has elapsed, open the first valve between the chamber and the pressure gauge to open the first valve. A control unit for comparing the measured pressure value of the chamber with the judgment pressure recorded in the judgment pressure recording unit, and outputting the comparison result. Prior to this, the first valve is closed and the pressure of the pressure gauge is maintained at the exhaust pressure at the end of the inspection.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIGS. 2 and 3 are operation flowcharts of the embodiment.
In FIG. 1, reference numeral 2 denotes a chamber for accommodating the inspection object 3, 5 an exhaust pump for exhausting air in the chamber 2, 8, 9 a pressure gauge, 10 a pressurizing device, 11 a tank, 12 a pressure gauge, and 13 Is a sealing member, 14 is a holding member, 15 is a cover, 16 is a spring, 17 is a tank, V ₁ , V ₂ , V ₃ , V ₄ , V ₈ , V ₉ and V ₁₁ are valves, and 24 is a judgment pressure recording section. , 25 is a clock unit for measuring a predetermined time, 26 is a control unit, 27 is an interface (I / O), and 28 is a processor (CPU) for executing processing. The pressure gauge 8 measures the vacuum pressure in the chamber 2, and the pressure gauge 9 measures the vacuum pressure in the tank 17.
[0009]
When the inspection object 3 has the input hole 3a and the output hole 3b in the inspection object 3, one of the output holes 3b is sealed with the lid 3c, and after being housed in the chamber 2, the chamber 2 is sealed with the lid 2a of the chamber. In addition, 2c is a packing.
[0010]
The inspection object 3 is placed by inserting the other unsealed input hole 3a into the opening of the sealing member 13 made of an elastic material such as rubber, and attached to the upper output hole 3b. 3 c is pressed by the pressing member 14.
[0011]
The holding member 14 is pressed down by a spring 16 provided between a convex portion 14 a provided on the holding member 14 and a sealed cover 15 attached to the lid 2 a of the chamber 2, and holds the inspection object 3. Press toward the bottom of chamber 2.
[0012]
The opening of the seal member 13 is connected to the tank 11 and the pressurizing device 10 by a pipe through the bottom of the chamber 2, and air pressurized by the pressurizing device 10 is supplied to the inspection object 3 through the tank 11. And pressurizes the inspection object 3.
[0013]
Next, the principle of the present embodiment will be described with reference to FIG.
Closing the valves V ₂ and V _11, the valve V ₄ as a third valve closing the valve V ₁ of the a second valve with pressurized to a predetermined pressure inside the inspection object 3 and the V ₈ and V ₉ in the open open allowed to exhaust previously tank 17 by the exhaust pump 5, as shown in FIG. 4, the pressure in the chamber 2 when the open valve V ₁ at time t = T ₁ is rapidly reduced to P ₃ than atmospheric pressure I do.
Therefore, it is possible to reduce the time to reduce the pressure in the chamber 2 to the pressure P ₃ than atmospheric pressure. As described above, when the pressure in the chamber decreases in a short time, a large pressure difference is generated between the pressure in the test object and the air in the test object leaks into the chamber. There is a pressure difference between the presence and absence of a leak.
Therefore, the inspection can be performed in a short time by reducing the pressure in the chamber in a short time.
[0014]
Incidentally, when the valve V ₁ is opened, so that the pressure in each chamber is P _3, so that measured by the pressure gauge 9 the pressure in the tank 17 prior to opening the valve V ₁ reaches a predetermined pressure adjustment are doing.
[0015]
Now, when there is no leak in the inspection object 3 stored in the chamber 2, the pressure in the chamber 2 decreases with time as indicated by A, but when the inspection object 3 has a leak, the air in the inspection object 3 Is leaked and released into the chamber 2, and as shown by B, a decrease in pressure with respect to time is reduced as compared with the case where there is no leak. By pressurizing the inside of the test object 3, the amount of leak from the test object 3 increases, and the decrease in pressure with respect to time decreases.
[0016]
The present invention is an application of this principle, in which a test object having a known allowable leak amount is stored in a chamber, and the relationship between time and pressure shown in FIG. 4 is obtained.
Next, a predetermined time T (T = T ₂ −T ₁ , T ₁ : valve opening time, T ₂ : measurement time) at which a certain pressure difference occurs with respect to no leak shown in FIG. The pressure P ₂ at the measurement time T ₂ is read, the read predetermined time T is set in the timer section 25, and the pressure P ₂ is recorded in the determination pressure recording section 24.
[0017]
When the pressure in the chamber 2 decreases, moisture or the like adhering to the outer surface of the inspection object 3 housed in the chamber 2 is released as a gas, and the released gas is added to the leak. The judgment pressure is recorded in the judgment pressure recording unit 24.
[0018]
Next, the operation of this embodiment will be described with reference to FIGS.
In step S21, the operator puts the inspection object 3 sealed with the lid on the input / output hole or the like in the chamber 2, covers the chamber 2 with the lid 2a, and seals it.
At step S40, the control unit 26 closes the valve V _1, and the valve V ₄ to open to start evacuation of air in the tank 17, the flow proceeds to step S41, the pressure gauge 9 pressure value predetermined vacuum pressure value wait until proceeds to step S22 to close the valve V ₄ proceeds to step S42 when a predetermined pressure value, in step S22, the control unit 26 closes the valve V _1, V ₈ and V ₉ Is opened to start pressurizing the test object 3 and the tank 11.
[0019]
In step S23, the control unit 26 reads the pressure value of the pressure gauge 12, determines whether or not the pressure has reached a predetermined pressure, and waits until the pressure reaches a predetermined pressure of, for example, 5 atm.
In step S24, the control unit 26 closes the valve V _9, maintain the pressure in the inspection object 3 and the tank 11 to a predetermined pressure. Thereafter, by closing the valve V ₂ proceeds to step S43, to exhaust the air in the chamber 2 by opening valve V ₁ and V _4.
[0020]
When by opening the valve V ₁ and valve V ₄ at step S43 to start the evacuation of the chamber 2 proceeds to step S44, immediately close the valve V _4, eliminate the exhaust of from tank 17. Subsequently, in step S26, when starting the evacuation of the chamber 2, the control unit 26 instructs the timer unit 25 to start measuring time.
[0021]
In step S27, the control unit 26 waits until the clocking unit 25 outputs a clocking completion signal for the predetermined time T '.
At step S28, the control unit 26, once opened again to close later valve V ₃ as a first valve of the pressure gauge 8.
[0022]
In step S29, the control unit 26 waits until the clocking unit 25 outputs a clocking completion signal for the predetermined time T ″.
In step S30, the control unit 26, the valve V ₃ to open.
Note will be explained later why opening and closing the valve V ₃ at step S27 to S30.
[0023]
In step S31, the control unit 26 waits until the clocking unit 25 outputs the clocking completion signal for the predetermined time T.
In step S32, the control unit 26 captures the pressure value P output from the pressure gauge 8 via the I / O 27, and proceeds to step S33 to determine that the captured pressure value P is recorded in the determination pressure recording unit 24. It determines whether less than the pressure P _2.
[0024]
In step S33, when the pressure value P is an inspection pass is lower than the reference pressure P ₂ is moved to step S34, also high proceeds to step S36 to output the inspection failure proceeds to step S35.
[0025]
At step S36, the control unit 26 stops the pressurization of the valve V ₈ to inspection object 3 in the closed stops the evacuation of the chamber 2 by closing the valves V ₁ and V _3. Further, the valves V ₂ and V ₁₁ are opened to bring the inside of the chamber 2 and the inside of the inspection object 3 to atmospheric pressure.
[0026]
In step S37, the operator opens the lid 2a of the chamber 2 to take out the inspection object 3, and moves to step S21 to start inspection of the next inspection object.
[0027]
Next, the reason for opening and closing the valve V ₃ at step S28, S30 and S36.
Inspection is completed, the pressure in the chamber 2 when the intake into the chamber 2 by opening the valve V ₂ in a state where the valve V ₃ to open at step S36 described above is abruptly changed to the atmospheric pressure than the exhaust pressure. For this reason, the pressure gauge 8 is damaged.
[0028]
Thus, by closing the valve V ₃ maintaining the pressure of the pressure gauge 8 to exhaust pressure at the completion of the inspection, the valve V ₃ starts examination of the next inspection object 3, open when approaching the time for determination of the leakage test To
[0029]
In the embodiment, the test object 3 and the tank 11 are pressurized. However, when the test object 3 has a large capacity, the pressurized pressure in the test object 3 can be increased even if a small leak occurs. The tank 11 may be removed because it is kept constant with little change.
In addition, if the pressurized device 10 sends out the pressurized air of a predetermined pressure, the test object 3 may be directly pressurized by the pressurizing device 10 during the inspection period.
[0030]
【The invention's effect】
As described above, according to the present invention, the inspection object is pressurized at the time of inspection, so that the amount of air leaked from the inspection object into the chamber increases, and the change in the exhaust pressure in the chamber decreases. The leak test can be performed accurately in a short time.
[Brief description of the drawings]
FIG. 1 is a block diagram of the present onset Ming embodiment.
FIG. 2 is a diagram showing a part of an operation flowchart of the embodiment of FIG. 1;
FIG. 3 is a diagram showing another portion of the operation flowchart of the embodiment of FIG. 1;
FIG. 4 is a diagram for explaining the principle of the embodiment of FIG. 1;
[Explanation of symbols]
2 Chamber 3 Inspection object 5 Exhaust pump 8, 9, 12 Pressure gauge 10 Pressurizing device 11, 17 Tank V ₁ Valve (second valve)
V ₃ Valve (first valve)
V ₄ Valve (third valve)
24 determination pressure recording unit 25 clock unit 26 control unit 27 interface (I / O)
28 Processor (CPU)

Claims (1)

A chamber for accommodating an inspection object in which input / output holes are sealed,
A pressure gauge for measuring a vacuum pressure in the chamber;
A first valve provided between the pressure gauge and the chamber;
A judgment pressure recording unit that records the judgment pressure,
A timing unit for measuring a predetermined time;
A pressurizing unit that pressurizes the inside of the inspection object housed in the chamber;
An exhaust pump,
A tank evacuated by the exhaust pump,
Second and third valves respectively provided between the exhaust pump, the chamber, and the tank;
Prior to the leak inspection, the second valve between the chamber and the chamber is closed, and the third valve between the tank and the tank is opened, and the tank is evacuated to a predetermined pressure by the exhaust pump. said third holding the valve closed predetermined inside the inspection object housed by Ri in the chamber to the pressure portion during the leak test between the tank pressure of the tank was evacuated to a When the pressure is increased to a predetermined pressure, the second and third valves are opened to exhaust the air in the chamber into the tank and to start timing at the timing unit. Open the first valve between the chamber and the pressure value of the chamber measured by the pressure gauge is compared with the determination pressure recorded in the determination pressure recording unit, and the comparison result output And a control unit that,
The leak control apparatus according to claim 1, wherein the control unit closes the first valve before sucking air into the chamber after the end of the inspection, and maintains the pressure of the pressure gauge at the exhaust pressure at the end of the inspection.

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