JP2000105165A - Temperature measurement method of leakage inspection device and leakage inspection device for correcting temperature by using the temperature measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the temperature difference of air in pressurization time and the completion time of inspection, and to correct drift that is the fluctuation in pressure being generated by temperature difference by applying pressure to an object to be inspected and fitting a temperature sensor to an exhaust passage from the object to be inspected. SOLUTION: In the drift correction of leakage inspection, temperature measurement being applied to a leakage detection device is made, for example, by applying pneumatic pressure to an object 2 to be inspected from an air source 1, by providing a branch path 13 at piping 12 for the exhaust of the object 2 to be inspected, and connecting a temperature measurement part 14 where a temperature sensor 11 is fitted to the branch path 13. When the pressure is to be applied, an opening/closing valve 15 is opened for a fixed amount of time for measuring the temperature of air when the pressure is applied. On the completion of inspection, the opening/closing valve 15 is opened for measuring the temperature of the air being evacuated from the object 2 to be inspected. Two temperature sensors may be independently used for the press and exhaust passages. The object 2 to be inspected without leakage is used, specific leakage inspection is made, and pressure and temperature are measured, thus obtaining a temperature correction coefficient used for calculating a drift correction value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a leak inspection apparatus for inspecting the presence or absence of leaks of various waterproof devices or instruments which should not leak such as gas fear, and the like. It relates to a temperature measuring method.

[0002]

2. Description of the Related Art A method shown in FIG.
There is a method shown in FIG. In the method shown in FIG. 6, the air pressure is
Is applied, the shutoff valve 3 is shut off after the application, the pressure in the test object 2 is measured by the pressure gauge 4, and the test object 2 leaks depending on whether or not the pressure value maintains a constant value for a predetermined time. This is a method of determining whether or not there is. Reference numeral 5 denotes a three-way solenoid valve, which operates as a means for conducting electricity between B and C after the inspection and exhausting the air pressure applied to the device under test 2 to the atmosphere.

The air pressure source 1 is equipped with a compressor, a pressure regulating valve, and a pressure gauge, and outputs a constant pressure air pressure. In the method shown in FIG. 8, air pressure is applied from the air pressure source 1 to the test object 2 and the reference tank 6 having no leakage, and after the application, the shutoff valve 3
Inspection object 2 and reference tank 6 while A and 3B are shut off
Is measured by the differential pressure gauge 7 to determine whether or not the test object 2 has leaked based on whether or not a differential pressure has occurred.

In any of the methods, if the temperature of the test object 2 is equal to the environmental temperature (air temperature), it is possible to perform a leak test without any particular problem. However, in actuality, the inspection object is carried to the inspection process through the processing process, and thus is often heated or cooled by welding or washing in the processing process. If the temperature of the test object is different from the ambient temperature,
The air applied to the test object expands or contracts depending on the temperature of the test object, and the applied air pressure fluctuates due to the expansion or contraction, so that an erroneous determination may be made.

[0005] Pressure fluctuations caused by the temperature of an object to be inspected are conventionally referred to as drifts, and various methods have been proposed for eliminating the effects of the drifts. For example, Japanese Patent Application Laid-Open No. Sho 59-206737 proposed by the present applicant is an example.
There is a leak inspection device having a temperature compensation function presented in Japanese Patent Application Laid-Open No. H10-260, 1988. Since the leak inspection apparatus presented above has been described in the above-described method, it will be described in the following method. Conventionally, a temperature sensor is brought into contact with the surface of the test object and the reference tank, and the surface temperature of the test object 2 and the reference tank 6 is measured. Is estimated, and a differential pressure value that would be generated due to the influence of heat from the temperature change is stored and prepared in advance as a drift correction value.

At the time of the actual inspection operation, a drift correction value corresponding to the temperature difference is read from the difference between the surface temperature of the test object 2 and the surface temperature of the reference tank 6 measured, and the drift correction value is measured at the time of inspection. Is subtracted from the correction value, and the presence or absence of leakage is determined based on whether or not the corrected differential pressure value is within a specified range.

[0007]

As described above, conventionally, the surface temperature of an object to be inspected is measured, and the inside air temperature is measured based on the surface temperature. Thus, it is clear that accurate measurements are not always guaranteed. However, temperature changes inside the test object,
Particularly, it is technically extremely difficult to measure the difference between the temperature at the time of pressurizing the air and the temperature at the end of the leak test.

An object of the present invention is to propose a method for measuring a temperature change of air applied to an object to be inspected and a leak inspection apparatus using the temperature measuring method.

[0009]

According to a first aspect of the present invention, there is provided a temperature measuring method applied to a leakage inspection apparatus for performing a leakage inspection by the above method. In a leak tester for applying a positive or negative air pressure to a test object to measure whether or not this air pressure maintains a constant value and to check whether or not the test object has a leak, a pressurizing passage for applying air pressure to the test object And, a temperature sensor is attached to an exhaust passage for exhausting the air pressure given to the test object from the test object,
The present invention proposes a temperature measuring method of a leak inspection device for measuring the temperature of air given at the time of pressurization and the temperature of air exhausted from an object to be inspected by the temperature sensor.

According to the temperature measuring method of the present invention, it is possible to actually measure the temperature change of the air received during the time when the air stays inside the test object. Therefore, by using this measured value, correct drift correction of the leak inspection can be performed. Claim 2 proposes a leak inspection apparatus using the temperature measurement method proposed in claim 1.

According to a third aspect of the present invention, a reference tank is used according to the temperature measuring method of the leak inspection apparatus for performing the leak inspection by the above method. Therefore, the temperature of the air injected into and exhausted from the reference tank depends on the environmental temperature. Can be seen as Therefore, in this case, it is possible to measure the temperature of the air when the test object is pressurized and the temperature of the air during the discharge only by measuring the temperature of the air exhausted from the test object and the reference tank, respectively. .

According to a fifth aspect of the present invention, there is provided a leak inspection apparatus for performing a leak inspection by a method, wherein a temperature sensor is provided only on an object to be inspected, and the temperature sensor measures the air temperature during pressurization and the air temperature during exhaust. It proposes a temperature measurement method. Claim 6 proposes a leak inspection apparatus using the temperature measuring method proposed in claim 5.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a method for measuring the temperature of a leakage inspection device proposed in claim 1 of the present invention and an embodiment of a leakage inspection device proposed in claim 2. The parts corresponding to those in FIG. 6 are denoted by the same reference numerals, and the duplicate description is omitted. However, the temperature measuring method of the leak inspection apparatus proposed in claim 1 of the present invention uses an air pressure The temperature sensor 11 is mounted on both the pressurizing passage for applying the pressure and the exhaust passage for exhausting the air pressure given to the test object from the test object.

In the embodiment shown in FIG. 1, a branch 13 is connected to a pipe 12 connecting the shut-off valve 3 and the device under test 2, and a temperature measuring unit 14 and an on-off valve 15 are connected to this branch 13; The temperature sensor 11 is mounted on the temperature measuring unit 14, and the on-off valve 15 is controlled to be open for a certain period of time during pressurization to measure the temperature of the air at the time of pressurization. Then, a part of the air exhausted from the test object 2 (exhaust is mainly performed by the three-way solenoid valve 5) is exhausted through the temperature measuring unit 14, and the temperature of the air exhausted from the test object 2 is set to 1
This shows a case where the structure is such that measurement is performed by the individual temperature sensors 11.
However, the present invention is characterized in that temperature sensors are attached to both the pressurizing passage and the exhaust passage, and may be configured to use two temperature sensors.

A calibration method when the temperature change of the air of the device under test 2 is measured using this temperature measurement method will be described below. That is, in order to obtain the drift correction value, first, a leak-free test object 2 in a normal temperature state is prepared, and this test object 2 is connected to the pipe 12.
0 and the exhaust air temperature T1 are measured. Further, the pressure difference ΔP1 from the time when a certain time (about several seconds) elapses after a certain equilibrium time after the shutoff valve 3 is shut off during pressurization is measured by the pressure gauge 4. From these measurements, the temperature difference ΔT1 of the air at normal temperature (temperature difference due to adiabatic compression and exhaust) is obtained by ΔT1 = T1−T0 (1).

Next, a leak-free test object 2 heated to a high temperature, for example, about several tens of degrees, is prepared, and this test object 2 is connected to a pipe 12. In this connection state, the air temperature T
0, the air temperature T2 at the time of exhaust, and the pressure change (pressure difference ΔP2) from the time when the shut-off valve 3 is shut off to the start of exhaust after a certain equilibrium time. From these measurements, the temperature difference ΔT2 of the air received by the high-temperature test object can be obtained by ΔT2 = T2−T0 (2).

Next, a temperature correction coefficient is obtained. The difference between the air temperature and the differential pressure value obtained by measurement under two different conditions is as follows: ΔT2−ΔT1 = Δt (3) ΔP2−ΔP1 = Δp (4) From these values Δt and Δp, the temperature correction coefficient is obtained. K can be obtained by the following equation: K = Δp / Δt (5)

When the temperature correction coefficient K is obtained, the drift correction value ΔP is determined by measuring the difference ΔT between the air temperature at the time of pressurization and the air temperature at the time of exhaustion at the time of an actual leak test, so that the drift correction value ΔP = K (ΔT− ΔT1)... (6)

The actual drift correction value ΔPs is as follows: ΔPs = K (ΔT−ΔT1) + ΔP1 (7) Therefore, by previously calculating and storing the temperature correction coefficient K, even when subsequently inspecting the test object 2 for leakage at an arbitrary temperature, the difference ΔT between the air temperature during pressurization and the air temperature during exhaustion can be calculated. By calculating, the drift correction value ΔP or ΔPs can be calculated. Since the drift correction value thus obtained is a result obtained by actually measuring the temperature of the air, the drift correction value is accurate and the inspection accuracy can be increased.

The embodiment shown in FIG. 1 shows a case where the temperature sensor 11 is provided and the branch path 13, the temperature measuring section 14, the on-off valve 15, and the throttle 16 are specially provided. As shown in FIG.
It is also conceivable to attach 1. For this purpose, for example, as shown in FIG. 3, a branch pipe 17 that can be connected in the middle of the pipe 12 is prepared, a branch port 17A is formed in the branch pipe 17, and an insulator is formed in the branch port 17A. Attach the sensor support plate 18 via the O-ring 18C,
7A, a cylindrical portion 18D protrudes from the center of the sensor support plate 18, and the temperature sensor 11 is mounted on the right side of the cylindrical portion 18D. Two conductive terminals 18A and 18A are provided on both sides of the cylindrical portion 18D. 18B, and the two conductive terminals 18A,
A temperature sensor 11 such as, for example, a thermistor is soldered and supported on the tip of 18B. This supporting position is selected near the position of the axis of the pressurizing and exhausting passages, and the temperature sensor 11 directly contacts the air passing through the pipe 12 at the time of pressurizing and exhausting, and measures the temperature of the air.

FIG. 4 shows an embodiment of a temperature measuring method of a leak inspection apparatus proposed in claims 3 and 4 of the present invention and a leak inspection apparatus using this temperature measuring method. A method for measuring the temperature of a leak inspection device proposed in claim 3 is a temperature measurement method for measuring the temperature of air at the time of pressurization and the temperature of air at the time of exhaust in a leak inspection device for inspecting the presence or absence of leakage by the above method. The one that suggests.

In FIG. 4, portions corresponding to those in FIG. 8 are denoted by the same reference numerals, and the description of the overlapping portions will be omitted.
In the present invention, pressurized air is supplied to the test object 2 and the pipe 12A through which the air exhausted from the test object 2 is passed at the end of the pressure change detection, and the pressurized air and the air exhausted are supplied to the reference tank 6. Each of the branch paths 13
A, 13B and the temperature measuring units 14A, 14B are connected to the ends of the branch paths 13A, 13B.
Opening / closing valves 15A, 15B and throttles 16A, 1 are provided before 14B.
6B are connected, and temperature sensors 11A and 11B are mounted inside the temperature measuring units 14A and 14B to form a temperature measuring unit.

According to this configuration, the temperature of the air exhausted from the reference tank 6 and the test object 2 is maintained at the normal temperature T0 and T1.
Can be seen as equal to the temperature of Therefore, in this embodiment, if the temperature of the air exhausted from the reference tank 6 and the temperature of the air exhausted from the device under test 2 are measured, the temperature of the air during pressurization and the temperature of the air during exhaust can be measured. .

Therefore, in the leak inspection apparatus having this structure, the measured value required for the calibration can be obtained only by measuring the temperature of the air exhausted from the test object 2 and the reference tank 6 even during the calibration. That is, at the time of calibration, the test object 2 in a normal temperature state with no leakage is prepared, and in this connection state, air pressure is applied from the pneumatic source 1 to the test object 2 and the reference tank 6. After applying
The shut-off valves 3A and 3B are closed, and the on-off valves 15A and 15B are controlled to be opened for a certain period of time after the time required for the inspection (about several seconds).
0 and T1 are determined. T0 is the temperature of the air exhausted from the reference tank 6, and T1 is the temperature of the air exhausted from the device under test 2. From this measurement, Δ shown in equation (1)
T1 can be determined. Further, a differential pressure value ΔP1 generated in the differential pressure gauge 7 at the time of opening and closing the exhaust gas is measured. After the measurement of the exhaust gas temperature, the three-way solenoid valve 5 is communicated between B and C to exhaust air from the test object 2 and the reference tank 6.

Next, a test object in a high temperature state without leakage is prepared, this test object 2 is connected to the pipe 12A, and pressurized air is applied to the test object 2 and the reference tank 6 in the connected state. I do. At the time when the time required for the inspection has passed after closing the shutoff valves 3A and 3B, the differential pressure value ΔP2 generated in the differential pressure gauge 7 is measured, and the open / close valves 15A and 15B are controlled to be open for a certain period of time.
The air is exhausted to the atmosphere through the temperature measuring units 14A and 14B, and the temperature of the exhausted air is measured. Thereafter, the three-way solenoid valve 5 is controlled to the exhaust state, and the air is exhausted from the test object 2 and the reference tank 6. The temperature of the air measured at this time corresponds to T2 and T0 shown in equation (2). Here, T2 is the temperature of the air exhausted from the test object 2 in the high temperature state, and T0 is the temperature of the air exhausted from the reference tank 6.

By these calibration operations, the equations (1) and (2)
ΔT1 and ΔT2 shown in the equations can be obtained, and Δt and Δp shown in the equations (3) and (4) can be obtained from the measured differential pressure values ΔP1 and ΔP2. As a result,
The temperature correction coefficient K shown in the equation (5) can be obtained. When the temperature correction coefficient K is obtained, the temperature correction coefficient K is stored, and the calibration is completed.

By storing the temperature correction coefficient K, the test object 2 having an arbitrary temperature can be connected to the pipe 12 in the actual test mode.
, The drift correction value ΔP can be obtained as shown in Expression (6) by measuring the temperature difference ΔT between the test object 2 and the air exhausted from the reference tank 6 at the time of exhaustion. In order to ensure accuracy, the drift correction value ΔPs shown in the equation (7) may be obtained.

As described above, in the case of the leak inspection apparatus using the reference tank 6, the temperature of the air exhausted from the reference tank 6 can be treated as the temperature of the air at the time of pressurization. The advantage is obtained that only the temperature of the air exhausted from the body 2 and the reference tank 6 needs to be measured. FIG. 5 shows a modification of the embodiment shown in FIG. In this embodiment, a case is shown in which the temperature of air at the time of exhaustion is measured using the branch pipe 17 shown in FIG.

FIG. 6 shows an embodiment of a temperature measuring method of a leak inspection device proposed in claims 5 and 6, and a leak inspection device using this temperature measuring method. The temperature measuring method and the leakage inspection device proposed in claims 5 and 6 are the inspection object 2 and the reference tank 6.
And a temperature measuring method for measuring the temperature of air at the time of pressurization and the temperature of air at the time of exhaust by using the temperature sensor 11. The present invention proposes a leak inspection apparatus configured to obtain a drift correction value ΔP from the temperature difference.

According to the temperature measuring method and the leak inspection apparatus proposed in the fifth and sixth aspects, only one temperature sensor can be used, so that the advantage that the configuration can be simplified can be obtained.

[0031]

As described above, according to the present invention, since the temperature of the air exhausted from the device under test 2 is measured, the influence of the temperature of the device under test 2 can be accurately grasped. As a result, the reliability of the temperature correction coefficient K obtained as the calibration value is high, and highly accurate drift correction can be realized.

[Brief description of the drawings]

FIG. 1 is a connection diagram for explaining an embodiment of a method and an apparatus for measuring a temperature of a leakage inspection device proposed in claims 1 and 2 of the present invention.

FIG. 2 is a connection diagram for explaining a modified embodiment of the embodiment shown in FIG. 1;

FIG. 3 is a sectional view for explaining an example of a mounting structure of a temperature sensor used in the embodiment shown in FIG. 2;

FIG. 4 is a connection diagram for explaining one embodiment of a method and an apparatus for measuring a temperature of a leakage inspection device proposed in claims 3 and 4 of the present invention.

FIG. 5 is a connection diagram for explaining a modification of the embodiment shown in FIG. 4;

FIG. 6 is a connection diagram for explaining one embodiment of a method and an apparatus for measuring a temperature of a leakage inspection device proposed in claims 5 and 6 of the present invention.

FIG. 7 is a connection diagram for explaining a conventional technique.

FIG. 8 is a connection diagram similar to FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pneumatic pressure source 2 Inspection object 3, 3A, 3B Shut-off valve 4 Pressure gauge 5 3-way solenoid valve 6 Reference tank 7 Differential pressure gauge 11, 11A, 11B Temperature sensor 12, 12A, 12B Pipe 13, 13A, 13B Branch path 14 , 14A, 14B Temperature measuring unit 15, 15A, 15B On-off valve 16, 16A, 16B Restrictor 17 Branch pipe 17A Branch port

Claims (6)

[Claims] 1. A leak inspection apparatus for applying a positive or negative air pressure to an object to be inspected and measuring whether or not the air pressure maintains a constant value to inspect whether or not the object to be inspected has a leak. A temperature sensor is mounted on a pressurizing passage for applying air pressure to the object to be inspected and an exhaust passage for releasing the air pressure applied to the object to be inspected from the object to be inspected. A temperature measuring method for a leak inspection apparatus, comprising: measuring a temperature of air and a temperature of air released from the test object. 2. A difference between the temperature of air at the time of pressurization measured by the temperature measuring method according to claim 1 and the temperature of air at the time of exhaustion is calculated, and a drift correction value is calculated based on the temperature difference.
A leak inspection apparatus characterized in that a pressure fluctuation component due to thermal expansion or contraction of air inside the inspection object is removed by the drift correction value. 3. A method for applying a positive or negative air pressure to an object to be inspected and a reference tank having no leakage, and inspecting whether or not the object to be inspected has a leak based on whether or not a difference occurs in the air pressure therebetween. A leak inspection device, wherein a temperature sensor is attached to an air release passage between the test object and the reference tank, and a temperature of air released from the test object and the reference tank is measured. Temperature measurement method. 4. A difference between the temperature of the air released from the test object and the temperature of the air released from the reference tank measured by the temperature measuring method according to claim 3, and a drift correction value is calculated based on the temperature difference. A leak inspection apparatus that calculates and removes a pressure fluctuation component due to thermal expansion or contraction of the air inside the inspection object by using the drift correction value. 5. A method for applying a positive or negative air pressure to an object to be inspected and a reference tank having no leakage, and inspecting whether or not the object to be inspected has a leak based on whether or not there is a difference in air pressure between them. In a leak inspection apparatus, a temperature sensor is mounted on a pressurized passage for applying air pressure to the object to be inspected and an exhaust passage for exhausting air pressure from the object to be inspected. A temperature measuring method for a leak inspection device, comprising: measuring a temperature and a temperature of air exhausted from the inspection object. 6. A temperature of air at the time of pressurization applied to the test object measured by the temperature measuring method according to claim 5,
Obtain the difference between the temperature of the air at the time of the exhaust and the temperature difference, calculate the drift correction value based on the temperature difference, and remove the pressure fluctuation component due to the thermal expansion or contraction of the air inside the test object using the drift correction value. Leakage inspection device characterized.