JPH10293075A - Instrument for measuring amount of leakage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the amount of leakage quickly and accurately by discharging a gas corresponding to a discharge flow rate that is recorded when measuring a differential pressure into a master chamber. SOLUTION: A control part 15 closes a valve V8 and prevents suction to a mounting tool 2, closes valves V3 and V4 , and opens V1 , V2 , and V5 -V7 . A master chamber 1, an inspection object, and the inside of the mounting tool 2 are evacuated by opening the valves V1 and V2 . Then, the control part 15 reads the indicated pressure of a pressure gauge 9 via an I/O 16, judges whether a measurement starting preparation pressure is appropriate or not, opens the valves V3 and V4 when the preparation pressure is reached, and then instructs an operator to close the valves V5 and V6 . The procedure is used to stop the swing of a differential pressure meter 4 quickly. Then, the control part 15 stands by until the instructed pressure of the pressure gauge 9 reaches a set pressure and closes the valves V1 and V2 when the set pressure is reached and then stops exhaust. The control part 15 reads a differential pressure DP1 that is indicated by the differential pressure meter 4 and a differential pressure DP2 after a set time passes. A part 14 for calculating the amount of leakage calculates and output the amount of leakage from the differential pressures DP1 and DP2 based on a specific expression.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak amount measuring device for measuring a leak amount of a container.

[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 measure the leak amount 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, methods for measuring a low leak amount include 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 cc / sec can be easily measured, 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. The time required for the measurement (response time) becomes long, and there is a disadvantage that the measurement system is enormous in measuring the leak amount of the product produced by the assembly work.

[0005] The vacuum leaving method is a method of measuring the leak amount from the difference between the pressure of the container and the pressure of the container after a predetermined period of time, by leaving the container of the test object at a set pressure (vacuum) and leaving it to stand. In the case of (1), there is a disadvantage that it takes a long time until the leak amount changes to a pressure at which measurement is possible.

[0006] differential pressure method, as shown in FIG. 5, the inspected object 3 which is attached to the master chamber 1 and the mount 2 is evacuated by the exhaust pump 5, the valve V ₁ and if it is evacuated to a predetermined pressure close V _2, and measures the amount of leakage by measuring the differential pressure in the differential pressure gauge 4 by opening the valve V ₃ and V _4.

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 the DP ₂ fixture + the volume of the inspection object is Q, the leak amount L is L = Q (DP ₁ −DP ₂ ) / T (1)

According to this method, the leak amount is 10 ⁻² cc / sec.
The degree can be easily measured in a short time. However, the products produced by the line work contain a lot of water vapor and other gases, and these gases are released and measured to measure the leak rate of 10 ^-5 cc / sec or less. The leak amount contained many errors and was not practical.

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

[0010]

[Means for Solving the Problems] Means adopted by the present invention to solve the above problems will be described. In the first invention, a leak amount measuring device for measuring the leak amount of the test object based on a change in a differential pressure between the master chamber and the test object attached to the fixture after exhausting air from the test object and sealing the test object. In the discharge flow rate recording unit that pre-records a value corresponding to the discharge flow rate of the gas released from the inspection object, and at the time of measuring the pressure difference between the two, the discharge flow rate recorded in the discharge flow rate recording unit Gas releasing means for releasing gas into the master chamber.

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.

The gas releasing means for releasing gas into the master chamber is composed of a regulator and a nozzle for adjusting the pressure of the gas, and the amount of release is changed by changing the pressure of the regulator. It is possible to release a gas. In the third invention, the discharge flow rate recorded in the discharge flow rate recording section is obtained by attaching a test object of the same type as the test object to the fixture, evacuating air, and a differential pressure immediately after sealing and after evacuation for a long time or The discharge flow rate is determined from the differential pressure in a state in which the discharge gas amount can be ignored by exhausting a plurality of times.

An inspection object of the same type as the inspection object is mounted on the fixture and exhausted, and the flow rate of the released gas is obtained from the difference between the differential pressure immediately after exhaustion and the leak amount calculated from the differential pressure after exhaustion for a long time. Therefore, the discharge flow rate recorded in the discharge flow rate recording unit can be accurately obtained without requiring a special device.

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.

According to a fifth aspect of the present invention, a measuring system for measuring a differential pressure between the master chamber and an inspection object attached to a fixture is provided by: a differential pressure gauge; one input of the differential pressure gauge; both of the exhaust means and a differential pressure gauge that performs the exhaust valve (V _3), the valve (V ₄₎ between the second input and the fitting of the differential pressure gauge, also the master chamber and inspected between Valves (V ₅ ,
V ₆₎ to provided, both valves of the connected open state to first exhaust means at the start of measurement of the differential pressure (V _5, V ₆₎ two valve wherein connected to the master chamber and fixture (V _3,
V ₄ ) is opened, and then both valves (V ₅ , V ₆ ) connected to the exhaust means are 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.

[0018]

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 fixture for mounting an inspection object 3, 4 is a differential pressure gauge, 5 is an exhaust pump, 6
Is a regulator for adjusting air pressure, 7 is a regulator 6
In the nozzle to release the pressure-regulated air 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 the 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 leak amount calculation unit, 15 is a control unit, and 16 is an interface (I /
O) and 17 are processors (CPU) that execute processing.

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. As the master chamber 1 and the mounting fixture 2, those having no leak and being aged in this way are used.

The discharge flow rate to be recorded in the discharge flow rate recording section is obtained by first mounting the test object of the same type as the test object on the fixture 2, and calculating the differential pressure of the differential pressure gauge 4 when the set vacuum pressure is reached, using the above-mentioned formula (1). ) by substituting the determined amount of leakage L _1. 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. In the case the capacity of the master chamber 1 Q 'and capacity Q fixture 2+ inspected 3 are unequal, (L ₁ -L ₂₎
The Q '/ Q is recorded as the release flow 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 1 can be obtained by precisely measuring the diameter of the nozzle 7, the relationship between the pressure and the discharge flow rate may be obtained 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.

The regulator control unit 13 reads the discharge flow rate recorded in the discharge flow rate recording unit 11 during the leak amount measurement described later, and converts the pressure corresponding to the read discharge flow rate by the flow rate pressure conversion unit 12. Then, the regulator 6 is controlled via the I / O 16 so that the pressure of the pressure gauge 8 input via the I / O 16 becomes the pressure converted by the flow pressure converter 12.

Next, the operation of the embodiment will be described with reference to FIGS. First, the inspection object 3 is attached to the fixture 2, and the operation is started. In step S1, the control unit 15
First performs initial setting of each valve V ₁ ~V _8.

[0027] That is, the air in the mount 2 by closing the valves V ₈ (hereinafter valve and short V _n) is prevented from being intake. The closed V ₃ and _{V 4, V 1, V 2} , V
_5, the V ₆ and V ₇ to open. In step S2, the exhaust pump and V ₁ and V ₂ is opened at step S1 5
As a result, air in the master chamber 1, the inspection object 3, and the fitting 2 is exhausted.

In step S3, the control section 15 reads the pressure indicated by the pressure gauge 9 via the I / O 16, determines whether or not the pressure has reached the measurement start preparation pressure, and waits until the preparation pressure is reached. That is, the process waits until the pressure reaches the pressure (set pressure) at the time of measuring the leak amount (set pressure).

In step S4, the controller 15 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 inputted first, it vibrates greatly, and it takes a long time until the oscillation stops. Therefore, first type having the same pressure the same 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, V ₅ and V ₆
Is closed to start 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
In 5, the control unit 15 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 S6, the control unit 15 determines that V ₁ and V
Close ₂ to stop evacuation.

In step S7, the control unit 15 controls the differential pressure gauge
Differential pressure DP indicated by 4₁And proceed to step S8.
After a set time (T) has elapsed, the process proceeds to step S9, where the differential pressure
DP _TwoTake in. In step S10, the leak amount calculation unit
14 is DP based on equation (1).₁And DP_TwoMore
The calculated amount L is output.

In step S11, the control unit 15
Close V ₃ , V ₄ and V ₇ and move to step S12,
To atmospheric pressure pouring air and the V ₈ to open the inspection object 3 and the mount 2. In step S13, the inspection object 3 is exchanged.

[0035] When the replacement of the test object 3 in step S13 is completed, the flow proceeds to step S14, the control unit 15 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 S2, and steps S2 to S14 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 are recorded, and if the discharge flow rate is changed with time, an accurate leak amount can be measured. it can.

In the embodiment, the leak amount is calculated in steps S7 to S10.
May be performed a plurality of times to calculate a plurality of leak amounts, and output the calculated plurality of average values as the leak amount.

[0038]

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 differential pressure measurement value and is not measured, and the true leak amount can be measured.

Further, the gas discharging means for discharging gas into the master chamber is composed of a regulator for adjusting the gas pressure and a nozzle, and the discharge amount is changed by changing the pressure of the regulator. And accurate gas release can be performed. In addition, the same type of inspection object as the inspection object is attached to the fixture and exhausted, and the flow rate of the released gas is obtained from the difference between the differential pressure immediately after exhaustion and the leak amount calculated from the differential pressure after long-time exhaustion. Therefore, the discharge flow rate recorded in the discharge flow rate recording section can be accurately obtained without requiring any special device.

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 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. Gone
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 configuration diagram of a conventional example.

[EXPLANATION OF SYMBOLS] 1 master chamber 2 fixture 3 inspected 4 differential pressure gauge 5 exhaust pump 6 regulator 7 nozzles 8,9 manometer V ₁ ~V ₈ valve 11 discharge flow rate recording unit 12 flow pressure converter unit 13 regulator control section 14 Leakage amount calculation unit 15 Control unit 16 Interface (I / O) 17 Processor (CPU)

Claims (5)

[Claims] 1. A leak amount measuring device for measuring a leak amount of an inspection object from a change in a differential pressure between the master chamber and an inspection object attached to a fixture after exhausting air from the inspection object, A discharge flow rate recording unit that records in advance a value corresponding to the release flow rate of the gas released from the inspection object, and a gas corresponding to the release flow rate recorded in the release flow rate recording unit when measuring the differential pressure between the two. A gas discharging means for discharging the gas into the master chamber. 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. The leak amount measuring device according to claim 1, further comprising: a flow rate pressure conversion unit that sets a pressure of the regulator so that the discharge amount is discharged from the nozzle. 3. An inspection object of the same type as an inspection object is attached to the fixture by measuring an emission flow recorded in the emission flow recording unit.
The discharge flow rate is obtained from the differential pressure immediately after the air is exhausted and sealed and the differential pressure after the exhaust for a long time or a plurality of times and the amount of the released gas is negligible. Item 3. The leak amount measuring device according to Item 1 or 2. 4. The leak amount measuring apparatus according to claim 1, wherein the gas discharged from the nozzle to the master chamber is air. 5. A measuring system for measuring a differential pressure between the master chamber and a test object attached to a fixture, comprising a differential pressure gauge, a valve between one input of the differential pressure gauge and the master chamber. V ₃ ), a valve (V ₄ ) between the other input of the differential pressure gauge and the fixture, and a valve (V ₄ ) between the exhaust means for exhausting the master chamber and the test object and both inputs of the differential pressure gauge. Valves (V ₅ , V ₆ ) are provided, and at the start of measurement of the differential pressure, both valves (V
₅ and V ₆ ), open both valves (V ₃ and V ₄ ) connected to the master chamber and the fixture, and then close both valves (V ₅ and V ₆ ) connected to the exhaust means. The method according to claim 1, wherein the differential pressure measurement is started.
The leak amount measuring apparatus according to 2, 3, or 4.