JP4923957B2 - Leak inspection device - Google Patents

Description

  The present invention relates to a leak inspection apparatus for inspecting whether or not there is a leak from an inspection object.

Known leak inspection apparatuses are described in Patent Documents 1 and 2 described later. In these devices, a test object is filled with a gas under pressure, and a change in pressure in the test object is measured to check whether there is a leak from the test object (hereinafter referred to as a leak test).
JP 2004-177275 A JP 9-33381 A

  In the above-described apparatus, the correction amount is determined based on the temperature of the object to be inspected, and this correction amount is added to the measurement result of the pressure change, thereby reducing the time required for the leak inspection. However, this method is based on the premise that measurement is performed in the same environment. Therefore, when the measurement environment changes, for example, when the temperature of the pressurized gas changes over time, the accuracy of the leak inspection is high. It will decline.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a leak inspection apparatus capable of reducing the time required for the leak inspection and further improving the accuracy of the leak inspection.

In order to solve the above-mentioned problem, the technical means taken in the present invention, as described in claim 1, is to fill a test object with a gas under pressure, and to adjust the gas in the test object. A leak inspection apparatus for inspecting the presence or absence of leakage of the gas from the inspection object by measuring a pressure change, wherein the leakage inspection apparatus is connected to the inspection object and discharges the gas in the inspection object And a flow rate adjusting mechanism that is provided in the discharge path and increases / decreases the flow rate of the gas per unit time in the discharge path so as to be filled with the gas in the inspection object, and from within the inspection object A temperature sensor that measures the temperature of the gas at a predetermined position between the flow rate adjusting mechanisms, and the flow rate adjusting mechanism is capable of linearly adjusting the flow rate of air in the discharge passage. It has a regulating valve, and the measurement result is higher than usual. In some cases, the closing speed of the proportional flow rate adjusting valve is decreased, and when the measurement result of the temperature sensor is lower than usual, the closing speed of the proportional flow rate adjusting valve is increased, and the pressure change is determined according to the measurement result. it is configured to Ru changing the measurement start timing and the fact.

  According to the first aspect of the present invention, since the gas in the inspection object is discharged to the outside through the discharge passage while the inspection object is filled with the gas, the compression heat accompanying the compression of the gas is generated. Can escape to the outside. Thereby, the temperature of the gas in a to-be-inspected object is stabilized quickly, and the time which a leak inspection requires can be shortened.

Further, since the temperature sensor is provided in the portion where the gas flow is created, the temperature in the object to be inspected can be directly measured with high accuracy. Accordingly, it is possible to always monitor whether or not the leak inspection is performed at an appropriate temperature based on the measurement result of the temperature sensor, and it is possible to perform the leak inspection with high accuracy. Even if the measurement result of the temperature sensor deviates from the reference value, the leak test can be performed at an appropriate temperature by changing at least one of the flow rate increase / decrease speed and the pressure change measurement start timing. Can be done accurately.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a leak inspection apparatus 1 according to the present invention. The leak inspection apparatus 1 fills the work 11 (inspected object) with gas under pressure, and measures the pressure change in the work 11 after a predetermined equilibration time has elapsed. (Hereinafter, leak inspection). Specifically, the leak inspection apparatus 1 inspects whether there is a leak from the work 11 based on a change in the differential pressure between the work 11 and the master 12 serving as a reference.

  The leak inspection apparatus 1 measures a pressure difference (differential pressure) between the pressure supply means 10 for applying a predetermined pressure to the inside of the workpiece 11 and the master 12 and the workpiece 11 and the master 12. Differential pressure measuring instrument 6, discharge path 25 for discharging the air in the work 11, proportional flow rate adjusting valve 22 for adjusting the flow rate of air in the discharge path 25 per unit time, and from the work 11 to the discharge path 25. A temperature sensor 24 for measuring the temperature of the flowing air and an arithmetic device 26 connected to the temperature sensor 4 are provided.

  The workpiece 11 is used in a state where a fluid flows through the workpiece 11. For example, a substantially closed space is formed by the workpiece 11 and a plate-like plate, and other than the two openings formed in the plate-like plate. Examples include a case where there is no channel connected to the outside, or a case where the workpiece 11 itself has two or more openings, and there is no channel connected to the outside other than the openings. The master 12 is in the shape of a hollow container with no leakage, and is in a state in which the same pressure is applied simultaneously with the workpiece 11 and is used as a reference for comparison with the workpiece 11 having a pressure that changes with the passage of time.

  The pressure supply means 10 supplies compressed air to the work 11 and the master 12 at a predetermined pressure to apply a positive pressure. The pressure supply means 10 is connected to the air pressure source 13 and the output side of the air pressure source 13. The pipes 14a and 14b for supplying compressed air to the workpiece 11 and the master 12 and valves 2 and 3 for opening and closing the pipes 14a and 14b, respectively, are connected. . A differential pressure measuring device 6 is provided between the pipe lines 14 a and 14 b via the pipe line 15. A valve 4 and a valve 5 are provided in the pipe line 15.

  The discharge path 25 is a pipe line that is connected to the inside of the work 11 and discharges the air in the work 11 to the outside. The discharge path 25 is provided with a valve 21, a proportional flow rate adjustment valve 22, and an exhaust device 23 such as a silencer. The air in the work 11 passes through the discharge path 25 and is discharged from the exhaust device 23 to the outside. The valve 21 opens and closes the discharge path 25. The proportional flow rate adjustment valve 22 (flow rate adjustment mechanism) can linearly adjust the flow rate of air in the discharge path 25. The valve 21 may not be provided as long as the proportional flow rate adjustment valve 22 can completely close the discharge path 25.

  The flow rate adjustment mechanism is not limited to the proportional flow rate adjustment valve 22 described above. For example, a flow rate adjusting valve (speaker) that determines the flow rate in advance may be applied in place of the proportional flow rate adjusting valve 22, and a sealed tank having a predetermined capacity may be applied in place of the exhaust device 23. In this case, the flow rate adjustment valve and the tank function as a flow rate adjustment mechanism.

  The temperature sensor 24 is a sensor such as a thermocouple, for example. The position of the temperature sensor 24 may be, for example, in the work 11 or in the connection part 30 between the work 11 and the discharge path 25 or the discharge path 25, and the temperature of the fluid in the work 11 is increased by compression due to pressurization. Any position that changes can be used. Here, the position of the temperature sensor 24 changes more than the internal volume and shape of the workpiece 11, and is obtained experimentally. In this embodiment, it is provided in the connection part 30 between the workpiece 11 and the discharge path 25.

  The computing device 26 is connected to the temperature sensor 24, and a measurement result (signal) at the temperature sensor 24 is input. The arithmetic device 26 is connected to a storage device 27. The storage device 27 stores data (leak inspection pattern) such as the temperature measured by the temperature sensor 24 and the opening / closing timing of each valve corresponding to this temperature. The arithmetic unit 26 compares the temperature (measurement result) measured by the temperature sensor 24 with the data in the storage device 27, and operates each valve based on the leak test pattern corresponding to the measurement result by the temperature sensor 24. . In addition to the temperature sensor 24 described above, a temperature sensor may be provided on the inlet side of the workpiece 11. In this case, the leak inspection can be more suitably performed using the measurement results of the two temperature sensors.

  Next, the leak inspection by the leak inspection apparatus 1 will be described with reference to FIG. FIG. 2 is a diagram illustrating the operation of each valve over time in the leak test. When the time T0 elapses from the start of the leak test, the valve 2 and the valve 3 are opened, and the valve 21 and the proportional flow rate adjusting valve 22 are opened. When the time T1 elapses, the proportional flow rate adjustment valve 22 starts to close. During time T <b> 1, the air supplied into the work 11 by the pressure supply means 10 is discharged to the outside through the discharge path 25, the valve 21, the proportional flow rate adjustment valve 22, and the exhaust device 23, and exists in the work 11. Exhaust atmospheric pressure air to the outside. Therefore, since the adiabatic compression of air is not performed in the work 11, the air temperature in the work 11 does not rise. When the time T2 elapses, the proportional flow rate adjustment valve 22 is completely closed and the valve 21 is also closed. During the time T2, since the proportional flow rate adjusting valve 22 is gradually closed, the resistance at the flow rate adjusting valve 22 is increased, and the pressure in the work 11 is increased. At this time, the air in the work 11 is adiabatically compressed and the temperature rises. However, since the air is immediately discharged to the outside from the proportional flow control valve 22, the temperature rises while the temperature rise is suppressed, and the heat quantity reaches the work 11 and the like. Since the heat is radiated, the air temperature in the work 11 is lowered.

When the time T3 elapses, the valves 2 and 3 are closed, the work 11 is filled with air, and the pressure in the work 11 becomes a predetermined test pressure in the leak inspection. Due to the action of the valve 21 and the proportional flow rate adjusting valve 22 described above, the air temperature in the work 11 is approaching a steady state when the time T3 has elapsed.

  Time T4 (equilibrium time) is a waiting time for stabilizing the air temperature in the workpiece 11. The valves 4 and 5 are opened in the middle of the time T4, and the differential pressure measuring device 6 communicates with the work 11 and the master 12. When the time T <b> 4 elapses, the differential pressure measuring device 6 starts measuring the differential pressure between the workpiece 11 and the master 12. This differential pressure is measured while the time T5 elapses. The valves 4 and 5 are closed while the time T5 elapses and the time T6 elapses. Based on the measurement result of the differential pressure at time T5, the presence or absence of leakage from the workpiece 11 is inspected.

  In the above-described leak inspection, for example, when the measurement result of the temperature sensor 24 after the time T1 has elapsed is higher than usual, the speed at which the proportional flow rate adjustment valve 22 closes, that is, the flow rate in the discharge passage 25 is It is also possible to increase the time T2 by decreasing the decrease rate. Similarly, when the measurement result of the temperature sensor 24 is lower than normal, the time T2 can be shortened by increasing the speed at which the proportional flow rate adjusting valve 22 closes. In addition to changing the time T2 according to the measurement result of the temperature sensor 24, changing the time T4 (equilibrium time) according to the measurement result of the temperature sensor 24 after the time T2 has elapsed, that is, It is also possible to change the measurement start timing of the pressure change of the air in the work 11 by the differential pressure measuring device 6. Even if an unexpected situation such as a sudden temperature change outside the work 11 occurs, whether the leak inspection conditions are normal according to the measurement result of the temperature sensor 24 during the time T4 and T5. Whether or not can be determined by the arithmetic unit 26, and if it is determined that there is an abnormality, it is possible to take measures such as restarting the leak inspection.

  FIG. 3 is a diagram illustrating a change in the air temperature in the workpiece 11 in the leak inspection. As shown in the figure, according to the leak inspection apparatus 1 of the present invention, the air in the work 11 is discharged to the outside through the discharge path 25 while the work 11 is filled with air. The compression heat accompanying the compression can be released to the outside, and the generation of the compression heat can be suppressed. Thereby, the temperature of the air in the workpiece | work 11 is stabilized quickly, and the time which a leak inspection requires can be shortened. Moreover, since the temperature sensor 24 is provided in the part where the air flow is created, the temperature in the workpiece 11 can be directly measured with high accuracy. Thereby, based on the measurement result of the temperature sensor 24, it can always be monitored whether the leak inspection is performed at an appropriate temperature, and a highly accurate leak inspection can be performed.

  Further, even when the measurement result of the temperature sensor 24 deviates from the reference pattern, the flow rate reduction rate and the time T4 (equilibrium time) by the proportional flow rate adjustment valve 22 are changed according to the measurement result of the temperature sensor 24. Thus, the leak inspection can be accurately performed at an appropriate temperature.

The figure which shows the structure of the leak test | inspection apparatus 1 which concerns on this invention. The figure which shows operation | movement of each valve | bulb with the time passage in a leak test | inspection. The figure which shows the change of the air temperature in the workpiece | work 11 in a leak test | inspection.

Explanation of symbols

1 Leak inspection device 11 Workpiece (inspection object)
22 Proportional flow control valve (flow control mechanism)
24 Temperature sensor 25 Discharge path T4 Time (equilibrium time)

Claims (1)

A leak inspection apparatus for inspecting the presence or absence of leakage of the gas from the inspection object by filling the inspection object with gas under pressure and measuring the pressure change of the gas in the inspection object. And
A discharge path connected to the inside of the inspection object, and for discharging the gas in the inspection object;
A flow rate adjusting mechanism that is provided in the discharge path and increases or decreases a flow rate of gas in the discharge path per unit time in order to fill the inspection object with the gas;
A temperature sensor that measures the temperature of the gas at a predetermined position between the flow rate adjusting mechanism from the inside of the inspection object, and
The flow rate adjustment mechanism has a proportional flow rate adjustment valve capable of linearly adjusting the flow rate of air in the discharge path,
When the measurement result of the temperature sensor is higher than normal, the closing speed of the proportional flow rate adjustment valve is decreased, and when the measurement result is lower than normal, the speed of closing the proportional flow rate adjustment valve is increased. the measurement result by the leak testing apparatus according to claim Rukoto changing the measurement start timing of the pressure change.

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