JP3382727B2 - Leak test equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention sets the same predetermined pressure inside a reference container and an object to be tested, and then based on the differential pressure generated between these reference container and the object to be tested, The present invention relates to a leak test device for measuring gas leak.

[0002]

2. Description of the Related Art Conventionally, as a device for inspecting leaks of containers and the like that require airtightness, a reference container that is not leaked or can be regarded as not leaked, and the inside of a DUT to be inspected are kept at the same predetermined pressure. After that, there is known a leak test device that measures the gas leak from the DUT based on the differential pressure generated between the reference container and the DUT. FIG. 5 shows an example of the leak test apparatus. The leak test apparatus 50 of this figure has a leak-free reference container 1, a test container 2 to be tested, and a gas supply source 3 for supplying a gas into these containers 1 and 2. Is. The leak test apparatus 50 is provided with a branched pipe 4 that connects the reference container 1, the container under test 2, and the gas supply source 3. A mechanical pressure reducing valve 51 and a three-way solenoid valve 52 that adjust the gas supplied from the gas supply source 3 to a predetermined pressure are provided in the trunk portion 4B on the upstream side of the branch portion 4A of the pipe 4. The three-way solenoid valve 52 includes a downstream side of the pressure reducing valve 51, a branch portion 4A of the pipe 4,
The exhaust pipe 5 is connected to the outside. The three-way solenoid valve 52 allows the branch portion 4A to selectively communicate with either the gas supply source 3 or the exhaust pipe 5.

Of the branch portions 4C and 4D of the branch portion 4A of the pipe 4, the branch portion 4C is connected to the reference container 1 and the branch portion 4D is connected to the container under test 2. The branch portion 4C is provided with a two-way solenoid valve 53, and a pressure guiding pipe 6A is provided downstream of the two-way solenoid valve 53.
Are connected. On the other hand, similarly to the branch portion 4C, the branch portion 4D is provided with a two-way solenoid valve 54, and the pressure guiding pipe 6B is connected to the downstream side of the two-way solenoid valve 54. A differential pressure sensor 7 is connected to the tips of the pressure guiding pipe 6A of the branch portion 4C and the pressure guiding pipe 6B of the branch portion 4D. A pressure gauge 8 is connected to the main portion 4B of the pipe 4 between the three-way solenoid valve 52 and the branch portion 4A.

Here, the three-way solenoid valve 52 and the two-way solenoid valve 5
3, 54 are electrically connected to the pipe switching device 9,
It is driven by an electric signal from the pipe switching device 9, and the drive causes the reference container 1 and the container under test 2 to be pressurized and sealed,
Exhaust is possible. Specifically, two-way solenoid valves 53, 54
By driving only the gas, the gas is supplied from the gas supply source 3 to the side of the reference container 1 and the side of the container 2 to be tested.
Pressurization of 2 is started. When the reference container 1 and the container under test 2 reach a predetermined pressure, the two-way solenoid valves 53, 54 are deactivated, and the reference container 1 side and the test container 2 side are closed. In this state, if there is a leak in the container under test 2, a differential pressure is generated between the reference container 1 side and the container under test 2 side. Therefore, the differential pressure sensor 7 detects the differential pressure between these containers 1 and 2. This will perform a leak test. After the test is completed, the three-way solenoid valve 52 and the two-way solenoid valves 53, 54 are driven to open the interior of the reference container 1 side and the container under test 2 side to the atmosphere and evacuate.

[0005]

Conventional leak test apparatus 50
Then, since the differential pressure sensor 7 connected to the reference container 1 side and the test container 2 side detects the differential pressure generated therebetween,
When the leak of the container under test 2 is large, the pressure of the container under test 2 is rapidly lowered, and the differential pressure thereof exceeds the measurement range of the differential pressure sensor 7. There is a problem that a leak test cannot be performed. On the other hand, if the differential pressure sensor 7 having a large measurement range is adopted, the resolution of the differential pressure sensor 7 becomes large, so that when the leak of the container 2 under test is small, there is a problem that a highly accurate leak test becomes impossible. Occur. Further, when a large differential pressure that clearly indicates that the test apparatus 50 is abnormal is detected, whether the cause is a mechanical failure such as malfunction of the solenoid valves 52 to 54 or clogging of the pipe 4, Alternatively, the differential pressure sensor 7
Since there is no clue to determine whether or not it is an electrical failure such as, there is also a problem that it takes time to find and repair the failed part and start the retest.

An object of the present invention is to provide a leak test apparatus which can perform a leak test accurately regardless of the amount of leak and which has a short time from failure to restoration.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a leak of an object to be tested is measured based on a differential pressure generated between a reference container and an object to be tested, which are hermetically sealed after the inside is brought to the same predetermined pressure. In the leak test apparatus, a differential pressure sensor for detecting a differential pressure between the reference container and the DUT, a reference pressure sensor for detecting an internal pressure of the reference container, and a measurement for detecting an internal pressure of the DUT. Pressure sensor and the differential pressure sensor
A differential pressure calculating means for calculating a differential pressure generated between the reference container and the DUT from the difference between the output signal of the reference pressure sensor and the output signal of the measuring pressure sensor when the output signal of the sensor reaches a predetermined value. It is characterized by being provided.

[0008]

According to the present invention, even if the differential pressure between the reference container and the device under test exceeds the measurement range of the differential pressure sensor in the leak test, the differential pressure is measured by the reference pressure sensor and measured. It can be detected from the difference from the detected value of the pressure sensor. Therefore, a small differential pressure can be detected with high accuracy by the differential pressure sensor, and a large differential pressure can be accurately detected by the reference pressure sensor and the measurement pressure sensor, so that the differential pressure measurement range is extremely large. Therefore, the leak test of the DUT can be accurately performed regardless of the amount of leak. Also, the internal pressures of the reference container and the DUT are detected in real time by the reference pressure sensor and the measurement pressure sensor, and the values of these internal pressures are used as clues to analyze the cause of the failure and identify the failed part. Since it becomes easy, it becomes possible to recover from a failure in a short time, and these can achieve the above-mentioned object.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the following description, the same members as those already described are designated by the same reference numerals, and the description thereof will be omitted or simplified. FIG. 1 shows a leak test apparatus 10 of this embodiment. The leak test apparatus 10 is provided with the branch portions 4C, 4D of the pipe 4.
Each of the reference pressure sensor 11 and the measurement pressure sensor
12 is provided. The reference pressure sensor 11 is a pressure sensor that detects the internal pressure of the reference container 1, and the measurement pressure sensor 12 is a pressure sensor that detects the internal pressure of the container 2 under test, which is the DUT. The leak test apparatus 10 is provided with a measuring apparatus 20 that measures a leak from the pressure detected by the reference pressure sensor 11 and the measurement pressure sensor 12 and the differential pressure detected by the differential pressure sensor 7.

The measuring device 20 includes a power supply unit 30 which is a power supply means for supplying electric power for measurement to the sensors 7, 11 and 12.
Three amplifiers 21 for amplifying the output signals of the sensors 7, 11 and 12
And a multiplexer that selectively outputs one of the signals from these amplifiers 21 according to a control signal from the outside.
22, an A / D converter 23 for converting the output signal from the multiplexer 22 from analog to digital, and the sensors 7, 11,
An arithmetic unit 40 for detecting leaks from the differential pressure or pressure detected in 12, and an indicator 24 for displaying leaks in the container under test 2
And an alarm device 25 for notifying an abnormality of the test apparatus 10. As shown in FIG. 2, the power supply unit 30 includes a power supply 31 for measurement, electrical contacts 32 to 34 interposed between the sensors 7, 11, 12 and the power supply 31, and a control signal from the arithmetic unit 40. And an operation circuit 35 for opening and closing each of the contacts 32 to 34 in accordance with the above. By this power supply unit 30, electric power is intermittently supplied to the sensors 7, 11 and 12 for, for example, 0.1 second in 2 seconds, heat generation due to energization to the sensors 7, 11 and 12 is suppressed, and a leak test is performed. The measurement error due to temperature fluctuation is reduced.

The arithmetic unit 40 is composed of a digital arithmetic unit such as a microcomputer and has a reference pressure sensor.
It is a differential pressure calculation means for calculating the differential pressure generated between the reference container 1 and the container under test 2 from the difference between the output signals of 11 and the measuring pressure sensor 12. In the input part of the arithmetic unit 40,
As shown in FIG. 3, a signal sorting section 41 is provided to switch the input so that the signals from the sensors 7, 11 and 12 are output to a predetermined destination. The first differential pressure signal, which is the differential pressure signal of the differential pressure sensor 7, is output from the output terminal a of the signal sorting section 41, the pressure signal of the reference pressure sensor 11 is output from the output terminal b, and the measurement signal is output from the output terminal c. The pressure signals of the pressure sensor 12 are output respectively. The output terminal B is connected to one input of the switching unit 42 having two inputs. Each of the output terminals (b) and (c) is connected to the first storage section 43 that stores the signal of the reference pressure sensor 11 and the second storage section 44 that stores the signal of the measurement pressure sensor 12, respectively.

At the output of the first storage unit 43 and the output of the second storage unit 44, a subtracting unit 45 for subtracting the measuring pressure sensor 12 from the signal of the reference pressure sensor 11 and outputting a second differential pressure signal. The output of the subtraction unit 45 is connected to the other input of the switching unit 42. The switching unit 42 receives the first differential pressure signal and the second differential pressure signal, and selectively outputs one of the first differential pressure signal and the second differential pressure signal in response to a switching command from the outside. It is a switching means. The differential pressure signal output from the switching unit 42 is input to the display output unit 46. The display output unit 46 is a control unit that controls the entire arithmetic unit 40.
The differential pressure signal of the switching unit 42 is directly output to the switch 47, and the indicator 24 and the alarm device 25 connected to the outside are driven according to the magnitude of the differential pressure signal. Output unit for display
The output of the first storage unit 43 and the output of the second storage unit 44 are also input to the 46 in order to monitor the pressures detected by the reference pressure sensor 11 and the measurement pressure sensor 12. Controller 47
While receiving the differential pressure signal output by the switching unit 42,
It is a control means that outputs a switching command to the switching unit 42 when the received differential pressure signal reaches a predetermined value within the measurement range of the differential pressure sensor 7. Further, the control unit 47 outputs a control signal to the external power supply unit 30 and the multiplexer 22.

Next, the operation of this embodiment will be described. In the leak test, in addition to the test process of performing the test, two processes, a pressurizing process and an equilibrium process, are performed as a preparatory process before the test process, and an exhaust process is performed as a post-treatment process after the test process. In performing each of these steps, as shown in Table 1, the solenoid valves 52 to 54 of the leak test apparatus 10 are sequentially opened and closed to switch the pipe 4.

[0014]

[Table 1]

Specifically, the container under test 2 which is the device under test
When the operation switch (not shown) of the pipe switching device 9 is turned on after setting the leak test device 10 to the leak test device 10, the two-way solenoid valves 53 and 54 are driven, and the gas is supplied from the gas supply source 3 to the reference container 1 and the container under test 2. The supply is started, and the reference container 1 and the container under test 2 are pressurized until the inside reaches a predetermined pressure. The pipe switching device 9 uses the internal timer to set a predetermined pressurizing process time T.
The pressurizing operation is continued until 1 has elapsed. Pressing process time T
After the passage of 1, the two-way solenoid valves 53, 54 are closed, the gas supply is stopped, and the next equilibration process is started. Equilibration process time T
After the lapse of 2, the test process is started and the leak test of the container 2 under test is performed. The operation of the measuring device 20 in the equilibrium and test process will be described in detail later. After the elapse of the predetermined test process time T3, the three-way solenoid valve 52 and the two-way solenoid valves 53, 54 are driven, the reference container 1 side and the container under test 2 side are opened to the atmosphere, and the predetermined exhaust process time is reached. After the elapse of T4, the evacuation process ends and the leak test is completed.

Subsequently, a measuring device in the equilibrium and test process
The operation of 20 etc. will be described. Calculation unit 40 during the equilibration process
Transmits a control signal for sequentially outputting the outputs of the differential pressure sensor 7, the reference pressure sensor 11, and the measurement pressure sensor 12 to the power supply unit 30 and the multiplexer 22, and the respective sensors 7, 11, 13 until the balance process is completed. Signal is sequentially monitored every predetermined period. Here, the reference pressure sensor 11, the measurement pressure sensor
By monitoring the signals of 12, it is possible to confirm whether the insides of the reference container 1 and the measured container 2 are pressurized to a predetermined pressure. Further, when the first differential pressure signal from the differential pressure sensor 7 becomes equal to or higher than a predetermined value, the test can be interrupted by notifying the display 24 and the alarm device 25 to that effect.
Further, in this case, for the container under test 2 in which the determination of leakage is made within the range of the first differential pressure signal, the test can be terminated when the first differential pressure signal becomes equal to or more than the predetermined value. By ending at that point, the test time is significantly reduced. In the test process, the calculation unit
The reference numeral 40 transmits a control signal for causing the power supply unit 30 and the multiplexer 22 to output only the output of the differential pressure sensor 7, and monitors the first differential pressure signal from the differential pressure sensor 7. This first
If the differential pressure signal of is less than or equal to the predetermined value, the above detection operation is repeated every predetermined period to measure the leak. Then, due to gas leakage, the internal pressure of the container under test 2 decreases,
When the first differential pressure signal reaches a predetermined value, the arithmetic unit 40
A control signal that causes the power supply unit 30 and the multiplexer 22 to output only the outputs of the reference pressure sensor 11 and the measurement pressure sensor 12 is transmitted, and the second differential pressure signal is output from the respective signals of the reference pressure sensor 11 and the measurement pressure sensor 12. Is calculated and the second differential pressure signal is monitored. Until the test process is completed, the above calculation operation is repeated every predetermined period to measure leakage.

According to this embodiment as described above, there are the following effects. That is, a reference pressure sensor 11 for detecting the internal pressure of the reference container 1 and a measurement pressure sensor 12 for detecting the internal pressure of the container under test 2 are provided, and the differential pressure between the reference container 1 and the container under test 2 is tested in the leak test. Even if the pressure exceeds the measurement range of the differential pressure sensor 7, the differential pressure is detected based on the difference between the detection value of the reference pressure sensor 11 and the detection value of the measurement pressure sensor 12. Is extremely large, and the leak test of the DUT can be accurately performed regardless of the amount of leak. Moreover, since the differential pressure sensor 7 can detect a small differential pressure with high accuracy and a large differential pressure can be accurately detected by the reference pressure sensor 11 and the measurement pressure sensor 12, the differential pressure measurement range is extremely small. Despite being large, leak tests can be performed with extremely high accuracy.

Further, since the internal pressure of each of the reference container 1 and the container 2 to be tested is detected in real time by the reference pressure sensor 11 and the measurement pressure sensor 12, even if the leak test apparatus 10 should fail. The values of these internal pressures serve as clues to facilitate the analysis of the cause of the failure and the identification of the failure part, so that the failure can be recovered in a short time.

Further, the power supply unit 30 for intermittently supplying electric power to the sensors 7, 11, 12 is provided to suppress heat generation due to energization of the sensors 7, 11, 12, so that a measurement error due to temperature fluctuation in the leak test may occur. The leakage test can be carried out with extremely high accuracy.

Although the present invention has been described with reference to the preferred embodiment, the present invention is not limited to this embodiment, and various improvements and design changes can be made without departing from the gist of the present invention. It is possible. For example, the means for adjusting the pressure of the gas supplied from the gas supply source is not limited to the pressure reducing valve 51, but an electronic control type such as an electro-pneumatic regulator that adjusts the pressure of the supply gas according to an electric signal from the outside. You may employ the thing.

Further, in the above embodiment, the solenoid valves 52 to 54 are used for switching the pipe 4, but instead of the solenoid valves, an electrically operated valve, a manual valve, and an operating device utilizing fluid pressure are used for driving. Valves can be used.

Further, in the measuring device 20 of the above-mentioned embodiment, the amplifier 21 is arranged before the multiplexer 22.
The position of 21 is, as shown in FIG.
It may be in the latter stage. In this way, only one amplifier 21 is needed and the other amplifiers 21 can be omitted.

The leak test apparatus according to the present invention can be used not only for the container test but also for the airtight test of pneumatic equipment or piping driven by gas pressure.

[0024]

As described above, according to the present invention, it is possible to accurately perform a leak test regardless of the amount of leak and to shorten the time from failure to recovery.

[Brief description of drawings]

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

FIG. 2 is a schematic configuration diagram showing a power supply unit that is the power supply means of the embodiment.

FIG. 3 is a schematic configuration diagram showing an arithmetic unit which is a differential pressure calculating means of the embodiment.

FIG. 4 is a diagram corresponding to FIG. 1 showing a modified example of the present invention.

FIG. 5 is a diagram corresponding to FIG. 1 showing an entire conventional example.

[Explanation of symbols]

1 standard container 2 Container under test as DUT 3 gas supply source 7 Differential pressure sensor 10 Leak test equipment 11 Reference pressure sensor 12 Pressure sensor for measurement 30 Power supply unit as power supply means 40 Arithmetic unit as means for calculating differential pressure 42 Switching unit as switching means 47 Control unit as control means

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-194257 (JP, A) JP-A-58-73836 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01M 3/26 G01M 3/02

Claims (3)

(57) [Claims] 1. A gas is supplied from a gas supply source to the inside of a reference container that has no leakage or is considered to be nonexistent and the DUT whose leakage is unknown, and the inside of these reference containers and the DUT are the same. In a leak test device for measuring the leakage of the DUT based on the differential pressure generated between the reference container and the DUT, the reference container and the DUT are sealed under the predetermined pressure of A differential pressure sensor that detects a differential pressure, a reference pressure sensor that detects the internal pressure of the reference container, a measurement pressure sensor that detects the internal pressure of the DUT, and an output signal of the differential pressure sensor is a predetermined value. a differential pressure calculation means for calculating a pressure difference generated between the difference in the output signal and the output signal of the measurement pressure sensor of the reference pressure sensor of the reference vessel and the DUT, that was provided Leakage test apparatus for the butterflies. 2. The leak test apparatus according to claim 1, wherein a difference between a first differential pressure signal obtained by the differential pressure sensor and an output signal of the reference pressure sensor and an output signal of the measurement pressure sensor is used. A switching means for inputting a certain second differential pressure signal and selectively outputting one of the first differential pressure signal and the second differential pressure signal in response to a switching command from the outside, and this switching means. While receiving the output differential pressure signal,
A leak testing apparatus, comprising: a control unit that outputs a switching command to the switching unit when the received differential pressure signal reaches a predetermined value. 3. The leak test apparatus according to claim 1, wherein the differential pressure sensor, the reference pressure sensor and the measurement pressure sensor are supplied with power for measurement intermittently. A leak test apparatus comprising means.