JP2001235386A - Leak inspecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leak inspecting device which performs a leak inspection with a simple construction, in a short time SOLUTION: The leak inspecting device wherein after the air in a master chamber 1 and in a chamber 2 containing an object 3 to be inspected with inlet and outlet holes and the like sealed is evacuated, the chambers 1, 2 are sealed, so that leak of the object to be inspected is detected by difference in pressure between the chambers 1, 2, in provided with a released flow recording unit 11 for previously recording a value corresponding to a released flow per hour of a gas contained in the object and released into the chamber 2, a gas releasing means for releasing, into the master chamber 1, a gas corresponding to the released flow recorded in the released flow recording unit 11, and a control unit 16 for comparing a determined value with a differential pressure value obtained when the master chamber 1 and the chamber 2 are sealed, following discharge of the air in the chambers, 1, 2 and a set time is clocked, and for output the result of the comparison.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak inspection apparatus for inspecting whether or not a leak amount of a container is below a standard value.

[0002]

2. Description of the Related Art At present, parts are sometimes hermetically sealed in order to improve the reliability of parts and the like. 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, gas leakage occurs. Therefore, it is necessary to determine whether the leak amount is within a specified value. Conventionally, as a method of inspecting a low leak amount, there are a method using a gas such as halogen and helium, a vacuum standing method, a differential pressure method and the like.

[0004]

The method using gas is 10
The leak amount of about ^-9 Pa · cc / sec can be easily inspected, but the running cost is high because the gas is used, the measuring device for detecting the leaked gas amount is complicated and expensive, and the gas leaks. There is a disadvantage that the time (response time) required until the measurement can be performed becomes long, and that the inspection system is enormous for inspecting the leak of the product produced by the assembly work.

[0005] The vacuum leaving method is a method in which the pressure of the container to be inspected is left at a set pressure (vacuum) and the leak is inspected based on the difference from the pressure of the container after a predetermined time. However, there is a disadvantage that it takes a long time before the leak amount changes to a pressure at which measurement is possible.

[0006] differential pressure method, as shown in FIG. 6, the inspected object 103 mounted on the master chamber 101 and fixture 102 was evacuated by the exhaust pump 105, valve V ₁ and if it is evacuated to a predetermined pressure close the V _2, valve V
₃ and V ₄ by opening and measuring a differential pressure in a differential pressure gauge 104 which measures the amount of leakage.

That is, assuming that the differential pressure measured at time t = T ₁ is DP _1, the differential pressure measured at time t = T ₁ + T is DP ₂ P = exhaust pressure, and the volume of fitting + inspection object is Q, the leakage amount L can be calculated by L = QP (DP ₁ -DP ₂ ) / T (1).

According to this method, the leak amount is 10 ⁻² Pa · cc.
It is possible to easily measure a value of about / sec in a short time. However, the product produced by the flow operation contains a lot of water vapor and other gases, and these gases are released to measure the leak amount of 10 ⁻⁵ Pa · cc / sec or less. The measured amount of leak contained many errors and was not practical.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a leak inspection apparatus capable of accurately performing a leak inspection in a short time with a simple apparatus configuration.

[0010]

[Means for Solving the Problems] Means adopted by the present invention to solve the above problems will be described. In the first aspect of the present invention, the air in the master chamber and the chamber accommodating the inspection object in which the input / output holes are sealed is evacuated and then sealed, and a leak of the inspection object is inspected from a change in a pressure difference between the two. In the leak inspection device, a gas contained in the inspection object is a discharge flow rate recording unit that records in advance a value corresponding to a discharge flow rate per unit time of gas released into the chamber,
A gas discharging means for discharging a gas corresponding to the discharge flow rate recorded in the discharge flow rate recording section to the master chamber at the time of measuring the differential pressure between the two, and a differential pressure measuring the differential pressure between the master chamber and the chamber; Manometer, a judgment pressure recording unit that records the judgment pressure, and a timer that counts a predetermined time,
The master chamber and the chamber are hermetically sealed after being evacuated and the timer is started by the timer, and when a predetermined time is counted, the differential pressure value of the differential pressure gauge and the judgment pressure recording unit are recorded. Comparison with the judgment pressure
And a control unit for outputting the result of the comparison.

A value corresponding to the discharge flow rate of the gas released from the test object is recorded in advance, and the gas corresponding to the discharge flow rate recorded at the time of measuring the differential pressure is discharged to the master chamber. The change in pressure due to the released gas is canceled out, and the true leak amount can be measured.

In the second invention, a regulator for regulating the gas discharge means to a gas set pressure, a nozzle for releasing the gas regulated by the regulator to the master chamber, and a discharge flow recording unit And a flow rate pressure converter for setting the pressure of the regulator so that the discharge amount recorded in the nozzle is discharged from the nozzle.

In a third aspect of the present invention, instead of recording the discharge flow rate in the discharge flow rate recording section, the pressure of the regulator obtained by converting the recorded discharge flow rate by the flow rate pressure conversion section is recorded. The converted pressure of the regulator is read and the pressure of the regulator is adjusted.

The gas discharge means for discharging gas into the master chamber is composed of a regulator and a nozzle for adjusting the pressure of the gas, and the discharge amount is changed by changing the pressure of the regulator. It is possible to release a gas.

In a fourth aspect of the present invention, the gas discharged from the nozzle to the master chamber is air. Since the gas released to the master chamber is air, no special gas is required and the running cost can be reduced.

In the fifth invention, the differential pressure gauge and the differential pressure gauge
A valve between one input of the manometer and the master chamber
(V_Three) With the other input of the differential pressure gauge and the chamber
Valve (V_Four) And the master chamber and
And both the exhaust means for exhausting the chamber and the differential pressure gauge
Each valve (V_Five, V₆), The difference
At the beginning of the pressure measurement, first open both sides connected to the exhaust means
Valve (V_Five, V₆) To said master chamber and said
Both valves connected to the chamber (V_Three, V _FourOpen)
And then both valves (V_Five, V
₆) Is closed to start differential pressure measurement.

At the start of the measurement of the differential pressure, first, both inputs of the differential pressure gauge are connected to the exhaust means to exhaust the gas, and then the differential pressure is measured by connecting the master chamber and the fixture.
The vibration of the differential pressure gauge is eliminated, the differential pressure can be measured immediately, and the accurate leak amount can be measured.

In a sixth aspect of the present invention, the control section outputs an inspection pass when the differential pressure value of the differential pressure gauge is lower than the judgment pressure recorded in the judgment pressure recording section.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of an embodiment of the present invention, and FIGS. 2 and 3 are operation flowcharts of the embodiment. In FIG. 1, 1 is a master chamber, 2 is a chamber for storing the inspection object 3, 4 is a differential pressure gauge, 5 is an exhaust pump,
6 regulator for adjusting the air pressure, 7 nozzles that release the air pressure regulated by the regulator 6 to the master chamber 1, 8 and 9 a pressure gauge, V ₁ ~V ₈ is a valve.

Reference numeral 11 denotes a discharge flow rate recording unit for recording a discharge flow rate discharged to the master chamber, and 12 denotes a pressure of the regulator 6 so that the discharge flow rate recorded in the discharge flow rate recording unit 11 is discharged to the master chamber. 13 is a regulator control unit, 14 is a judgment pressure recording unit that records a judgment pressure, 15 is a clock unit, 16 is a control unit, 17 is an interface (I / O), and 18 is a processor that executes processing. (CPU). The inspection object 3 seals the input / output hole with the lid 3a and, after being housed in the chamber 2, seals the chamber 2 with the lid 2a of the chamber. In addition, 2b is a packing.

First, the discharge flow rate recorded in the discharge flow rate recording section 11 will be described. When the test object is at a certain vacuum pressure,
Since the test object contains water vapor and other gases,
Gas is released as shown in FIG. The gas discharge flow rate is initially large and decreases with time. When a vacuum is applied for a long time, most of the gas is released and the gas is not released. Master chamber 1 and chamber 2 have no leak,
In addition, an aged state is used.

The discharge flow rate to be recorded in the discharge flow rate recording unit is firstly stored in the chamber 2 by sealing the input / output holes and the like with the test object of the same type as the test object. determining the leakage amount L ₁ of the differential pressure into equation (1) described above. Also it includes discharge gas amount in addition to the true amount of leakage in the thus determined was L _1.

Next, after maintaining the vacuum state for a long time, or by repeating the vacuum state many times, the set vacuum pressure is again set in a state where the released gas can be neglected. Ask for ₂ . Thus L ₂ obtained by the is only true leakage quantity. Therefore, the discharge flow rate L ₃ is calculated by performing the calculation of L ₁ −L ₂ and recorded in the discharge flow rate recording unit 11 in advance. If the capacity Q 'of the master chamber 1 is not equal to the capacity Q of the chamber 2 containing the inspection object 3, (L ₁
-L ₂₎ records the Q '/ Q as release rate L _3.

Next, the flow rate pressure converter 12 will be described. If the diameter of the hole of the nozzle 7 and the vacuum pressure of the master chamber 1 are determined, the relationship between the pressure regulated by the regulator 6 and the discharge flow discharged to the master chamber 1 can be obtained.

Although the pressure of the regulator 6 can be determined by precisely measuring the diameter of the nozzle 7, the relationship between the pressure and the discharge flow rate may be determined by the method using gas described in the conventional example. The pressure of the regulator corresponding to the discharge flow rate thus obtained is recorded in the flow rate pressure converter 12 in advance.

During a leak test described later, the regulator control section 13 reads the discharge flow rate recorded in the discharge flow rate recording section 11 and converts the pressure corresponding to the read out discharge flow rate by the flow rate pressure conversion section 12. , The regulator 6 is controlled via the I / O 17 so that the pressure of the pressure gauge 8 becomes the pressure converted by the flow pressure converter 12 via the I / O 17.

Next, the operation of the embodiment will be described with reference to FIGS. In step S1, the operator places the inspection object 3 sealed with the lid on the input / output hole or the like in the chamber 2, and seals the chamber 2 with the lid. In step S2, the control unit 16 first performs initial setting of each valve V ₁ ~V _8.

That is, the valve V ₈ (hereinafter, abbreviated to V _n ) is closed to prevent air from being sucked into the chamber 2. The closed V ₃ and _{V 4, V 1, V 2} ,
The V _5, V ₆ and V ₇ to open. In step S3,
V ₁ and V ₂ in step S2 is air in the master chamber 1 and the chamber 2 is exhausted by an exhaust pump 5 is opened.

In step S4, the control section 16 reads the pressure indicated by the pressure gauge 9 via the I / O 17, determines whether or not the pressure has become the measurement start preparation pressure, and waits until the measurement pressure becomes the preparation pressure. That is, the process waits until the pressure reaches the preparatory pressure provided until the pressure at the time of the leak test (set pressure) is reached.

In step S5, the control unit 16 sets the preparatory pressure
V when it comes to strength_ThreeAnd V_FourAnd then V_Fiveand
V₆To close. Thus, first, V_FiveAnd
And V₆With V open_ThreeAnd V_FourOpen and V _FiveYou
And V₆The reason for closing is that the swing of differential pressure gauge 4 stops in a short time.
It is to stop.

A high-sensitivity differential pressure gauge has a long oscillation cycle, and when a signal having a large differential pressure is input first, it vibrates greatly, and it takes a long time until the oscillation stops. Therefore, first type having the same pressure V ₅ and V ₆ is opened condition, then even open V ₃ and V _4, the influence due to the pressure difference becomes negligible, the V ₅ and V ₆ It closes and starts measuring the differential pressure.

By enabling the measurement of the differential pressure to be started in a short time, an accurate leak amount can be measured. That is, the amount of released gas greatly changes with time as described with reference to FIG. Therefore, if the time until the vibration stops is greatly different, a difference occurs between the discharge flow rate recorded in the discharge flow rate recording unit 11 and the gas amount actually discharged from the inspection object, and the measurement result of the leak amount Although a large error occurs, if it can be measured in a short time, it will be the same as the recorded discharge flow rate, and the error will not be included.

Next, returning to the operation, step S
At 6, the control unit 16 determines whether the pressure indicated by the pressure gauge 9 has reached the set pressure, and waits until the pressure reaches the set pressure. In step S7, the control unit 16 determines that V ₁ and V
₂ is closed to stop the evacuation and to instruct the timer unit 15 to start time measurement.

In step S8, when the set time (T) has elapsed, the control section 16 proceeds to step S9 and shifts to the differential pressure DP.
Take in. In step S10, the control unit 16 determines whether the differential pressure value DP captured in step S9 is smaller than the determination pressure P recorded in the determination pressure recording unit 14.

If the determination in step S10 is YES, the process proceeds to step S11, and if the determination is NO, the process proceeds to step S12 to output an inspection failure, and the process proceeds to step S13.

As shown in FIG. 5, at time t = T ₀ , V
Differential pressure values D of the differential pressure gauge 4 at the time of stopping the exhaust of the master chamber 1 and chamber 2 closes the ₁ and V ₂
P is 0. In the evacuated vacuum state, the water vapor adhering to the inspection object 3 stored in the chamber 2 evaporates and releases gas into the chamber 2. However, since the gas corresponding to the amount of the released gas is released into the master chamber 1, the differential pressure value DP becomes 0 when the inspection object 3 has no leak.

If the inspection object 3 has a leak, the inspection object 3
The air sealed at atmospheric pressure is released into the chamber 2, and the pressure difference between the master chamber 1 and the chamber 2 increases with time, as shown in FIG. 5. Therefore, the differential pressure value DP = P corresponding to the leak amount that satisfies the standard when the time T has elapsed from the time T ₀ is recorded in advance in the determination pressure recording unit 14 as the determination pressure. If> P, a failure is output.

In step S13, the control unit 16
Proceeds to step S14 to close the V _3, V ₄ and V _7,
To atmospheric pressure pouring air into the chamber 2 by a V ₈ to open. In step S15, the inspection object 3 is replaced by opening the lid of the chamber 2.

[0039] When the replacement of the test object 3 in the step S15 is completed, the flow proceeds to step S16, the control unit 16 closes the V _8, the V ₁ and V ₂ as well as the V _5, V ₆ and V ₇ to Open Open , And the process proceeds to step S3, and steps S3 to S16 are repeated.

In the embodiment, the discharge flow rate recorded in the discharge flow rate recording unit 11 is set to one point.
When the time T set in the above is small, and when T is large, a plurality of discharge flow rates within the time T may be recorded, and the discharge flow rate may be changed over time.

In the embodiment, the discharge flow rate recorded in the discharge flow rate recording section is read out and converted into the pressure by the flow rate pressure conversion section. However, the converted pressure is recorded, and the recorded pressure is converted into the pressure. The reading may be performed to regulate the pressure of the regulator.

[0042]

As described above, according to the present invention, the following effects can be obtained. A value corresponding to the release flow rate of the gas released from the test object is recorded in advance, and the gas corresponding to the release flow rate recorded at the time of measuring the differential pressure is released to the master chamber. The change in pressure due to the gas is canceled out by the measured differential pressure value and is not detected, and only the true leak amount can be obtained.

Further, the gas discharging means for discharging gas into the master chamber is composed of a regulator and a nozzle for adjusting the pressure of the gas, and the discharge amount is changed by changing the pressure of the regulator. And accurate gas release can be performed.

Further, since the gas released to the master chamber is air, no special gas is required, and the running cost can be reduced. Also, at the start of measuring the differential pressure, first, both inputs of the differential pressure gauge are connected to the exhaust means to exhaust the gas, and then the differential pressure is measured by connecting the master chamber and the chamber. Thus, the differential pressure can be measured immediately, and the accurate leak amount can be measured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an operation flowchart of the embodiment.

FIG. 3 is an operation flowchart of the embodiment.

FIG. 4 is a diagram for explaining a released gas amount with respect to time.

FIG. 5 is a diagram for explaining a differential pressure value with respect to time.

FIG. 6 is a configuration diagram of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Master chamber 2 Chamber 3 Inspection object 4 Differential pressure gauge 5 Exhaust pump 6 Regulator 7 Nozzle 8,9 Pressure gauge V ₁ -V ₈ Valve 11 Release flow recording part 12 Flow pressure conversion part 13 Regulator control part 14 Judgment pressure recording part 15 Timing Unit 16 Control unit 17 Interface (I / O) 18 Processor (CPU)

Claims (6)

[Claims] 1. A leak test for evacuating air from a master chamber and a chamber containing a test object in which input / output holes and the like are sealed, and then sealing the test object and checking a leak of the test object based on a change in a pressure difference between the two. In the apparatus, a gas contained in the inspection object is configured to previously record a value corresponding to a release flow rate per unit time of a gas released into the chamber. A gas discharging means for discharging a gas corresponding to a discharge flow rate recorded in a flow rate recording unit to the master chamber; a differential pressure gauge for measuring a differential pressure between the master chamber and the chamber; a determination pressure for recording a determination pressure A recording unit, a timing unit for timing a predetermined time, and sealing after exhausting the air in the master chamber and the chamber and starting the timing in the timing unit for a predetermined time. When the time is measured, the differential pressure value of the differential pressure gauge is compared with the judgment pressure recorded in the judgment pressure recording unit,
And a control unit for outputting the result of the comparison. 2. A regulator for regulating the pressure of the gas to a predetermined pressure, a nozzle for discharging the gas regulated by the regulator to the master chamber, and a gas recorded in the discharge flow rate recording unit. 2. The leak inspection apparatus according to claim 1, further comprising: a flow rate pressure converter configured to set a pressure of the regulator so that a discharge amount is discharged from the nozzle. 3. The pressure of the regulator obtained by converting the recorded discharge flow rate by the flow rate pressure conversion section instead of recording the discharge flow rate of the discharge flow rate recording section, and recording the recorded converted flow rate. 3. The leak inspection apparatus according to claim 2, wherein the pressure of the regulator is read to adjust the pressure of the regulator. 4. A gas discharged from the nozzle to the master chamber is air.
Or the leak inspection device according to 3. 5. A valve (V ₃ ) between one input of the differential pressure gauge and the master chamber, a valve (V ₄ ) between the other input of the differential pressure gauge and the chamber, and A valve (V) is provided between the exhaust means for exhausting the master chamber and the chamber and both inputs of the differential pressure gauge.
_5, V ₆₎ to provided, both valves (V ₅ of the connected open state to first exhaust means at the start of measurement of the differential pressure, V the master chamber and the is connected to the chamber both valves ₆₎ (V ₃ , V ₄ ), and then both valves (V ₅ , V ₆ ) connected to the exhaust means are closed to start differential pressure measurement.
The leak inspection device as described. 6. The control unit according to claim 1, wherein the control unit outputs an inspection pass when the differential pressure value of the differential pressure gauge is lower than a judgment pressure recorded in the judgment pressure recording unit. The leak inspection apparatus according to 2, 3, 4 or 5.