JP2018124161A - Leakage inspection device and leakage inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leakage inspection method and a device with which it is possible to appropriately temperature-compensate an effect of a temperature change included in a measurement result.SOLUTION: Before and after a leakage inspection step of measuring a pressure change in a container to be inspected, which is sealed after being pressurized to an inspection pressure, a pre-correction step and a post-correction step of measuring the pressure change in the container to be inspected, which is sealed after exposure to atmospheric air, are carried out. A first temperature compensation value H1 is obtained from a measurement result of the pre-correction step and a second temperature compensation value H2 is obtained from the measurement result of the post-correction step, the first temperature compensation value H1 and the second temperature compensation value H2 are weighted by weighting factors α, β and then averaged, a result obtained as a temperature compensation value H3 at leakage inspection time, with the measurement result of the leakage inspection step thereby temperature-compensated and determination made as to the presence of leakage from the container to be inspected. The weights of the first temperature compensation value H1 and the second temperature compensation value H2 are changed on the basis of at least one of magnitude of an inspection pressure, magnitude of heat capacity of the container to be inspected, magnitude of a coefficient of heat transfer to the outside, and magnitude of a temperature difference between the container to be inspected and an environment.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a leak inspection apparatus and a leak inspection method for inspecting a leakage of a container or a pipeline to be inspected.

  When inspecting for leaks in a container, a method is generally employed in which a gas such as air is pressurized and introduced into the container at a high pressure and then sealed, and the subsequent pressure change is observed.

  However, the observed pressure change includes not only the pressure change due to leakage but also the pressure change due to temperature fluctuation.

  Therefore, various techniques for removing the influence of the pressure change caused by the temperature fluctuation from the pressure change measured by the leak test have been proposed.

  For example, in Patent Document 1 below, a pressure change when a container to be inspected is left in a sealed state after being opened to the atmosphere is measured, and a temperature variation (mainly a change in environmental temperature) that occurs at the time of leakage inspection is measured from the measurement result. ), And an inspection method and apparatus for removing the influence of temperature fluctuation from the actual measurement result of the leakage inspection are disclosed. In this inspection method, in order to more accurately remove the influence of temperature fluctuation, the pressure change caused by the temperature fluctuation is measured before and after the actual leakage inspection, and the average value of the pressure change rate obtained by the previous and subsequent measurements. Based on the above, the effect of temperature fluctuation at the time of leak inspection is removed.

  Patent Document 2 listed below discloses a leakage inspection method that detects the presence or absence of workpiece leakage by measuring a differential pressure between a workpiece that is a container to be inspected and a master that is a container without leakage. Specifically, a leakage inspection is performed in which a change in differential pressure when the workpiece and the master are pressurized to the same pressure and then left in a sealed state is measured for a predetermined time. At this time, one of the workpiece and the master is strongly affected by temperature fluctuations such as the environmental temperature, and a differential pressure may be generated even though it is not leaking. Therefore, before and after this leakage inspection, a temperature compensation measuring step is performed for measuring a change in the differential pressure (degree of influence) when the workpiece and the master are left in a sealed state after being released to the atmosphere for a predetermined time. Do. Then, using the average value of the temperature compensation value (differential pressure change rate) obtained in the previous and subsequent temperature compensation measurement steps, the amount of change in the differential pressure based on the temperature fluctuation during the leak test is estimated, and the leak test Compensate the temperature of the measurement result.

  Further, in Patent Document 2, the first time from when the temperature compensation measurement process before the leak test is performed until the leak test is performed, and the first time until the temperature compensation measurement process after the leak test is performed. In consideration of the case where there is a difference between 2 hours, the temperature compensation value obtained in the temperature compensation measurement process before the leak test and the temperature compensation value obtained in the temperature compensation measurement process after the leak test are set to the first time. It is disclosed that the measurement result at the time of leak inspection is temperature-compensated with a weighted average value with the inverse ratio of the second time.

Japanese Patent No. 348253 Patent No. 4994494

  In both Patent Documents 1 and 2, basically (when the above-mentioned first time and second time are the same), the temperature compensation value obtained by the measurement before and after the leak test (the rate of change in pressure and differential pressure) ) Is used to estimate the temperature compensation value based on the temperature fluctuation during the leak test, and to compensate the temperature of the measurement result of the leak test. The average value is used on the premise that the inspection object (workpiece) is at substantially the same temperature as the environmental temperature, and that the temperature change during measurement occurs gently due to the environmental temperature change. That is, since the environmental temperature changes gently, the difference between the temperature compensation value obtained in the temperature compensation measurement process before the leak inspection and the temperature compensation value obtained in the temperature compensation measurement process after the leak inspection is small. This is based on the fact that the change in temperature compensation value is considered to occur almost linearly.

  However, when the workpiece to be inspected is hot (for example, when it is 3 to 5 degrees higher than the environmental temperature and the master is substantially environmental temperature), the temperature difference between the workpiece temperature and the environmental temperature is initially large. The workpiece temperature changes drastically, and thereafter, as the temperature difference between the workpiece temperature and the environmental temperature becomes smaller, the workpiece temperature change becomes slow. Naturally, the differential pressure between the workpiece and the master also changes drastically at the beginning and gradually becomes slow. As a result, the difference between the temperature compensation value obtained in the temperature compensation measurement process before the leak inspection and the temperature compensation value obtained in the temperature compensation measurement process after the leak inspection is large, and the change in the temperature compensation value during that period is almost linear. The assumption that occurs in The change in the temperature compensation value is considered to occur in a nonlinear curve shape.

  For example, when the workpiece to be inspected is manufactured by brazing, welding, casting process, etc., the temperature of the workpiece immediately after manufacturing is very high, so the difference from the environmental temperature is large, It doesn't hold.

  Furthermore, if the inspection pressure at the time of leakage inspection is set to a high pressure such as 500 KPa (G), the temperature rise due to adiabatic compression when pressurizing to the inspection pressure and the temperature drop due to adiabatic expansion when decompressing are large. The temperature will be lower than before pressurization. As a result, the linear assumption is further inaccurate.

  On the other hand, in order to start leakage inspection after sufficiently cooling the hot workpieces manufactured as described above to the ambient temperature, there is a wide storage place for storing a number of workpieces manufactured one after another until they are cooled. It becomes necessary.

  It should be noted that the heat capacity of the workpiece and the heat transfer coefficient to the outside also affect the temperature change of the workpiece.

  The present invention has an object to solve the above problem, and even when the inspection pressure is high or the inspection is performed in a state where the temperature difference from the environmental temperature is large, the influence of the temperature fluctuation included in the measurement result is appropriately obtained. An object of the present invention is to provide a leak inspection method and a leak inspection apparatus that can compensate for temperature.

  The gist of the present invention for achieving the object lies in the inventions of the following items.

[1] A leak inspection method for inspecting whether there is a leak in a container to be inspected,
A first measurement step of measuring a pressure change in the inspection target container sealed after being opened to the atmosphere in a first period;
A second measurement step of measuring a pressure change in the container to be inspected sealed after being opened to the atmosphere in a second period after the first period;
A pressure change in the inspection target container sealed after pressurizing the inspection target container to a predetermined inspection pressure is measured between the first period and the second period or in a third period after the second period. A third measuring step,
A first temperature compensation value calculating step for obtaining a first temperature compensation value based on the measurement result of the first measuring step;
A second temperature compensation value calculating step for obtaining a second temperature compensation value based on the measurement result of the second measuring step;
A third temperature compensation value calculating step for calculating a third temperature compensation value for temperature compensating the measurement result of the third measurement step based on the first temperature compensation value and the second temperature compensation value;
A determination step of determining the presence or absence of leakage of the inspection target container based on data obtained by performing temperature compensation on the measurement result of the third measurement step with the third temperature compensation value;
Have
In the third temperature compensation value calculation step, at least one of the magnitude of the examination pressure, the magnitude of the heat capacity of the examination target container, the magnitude of the heat transfer rate to the outside, and the magnitude of the temperature difference between the examination target container and the environment The leak inspection method according to claim 1, wherein the weighting of the first temperature compensation value and the second temperature compensation value in calculating the third temperature compensation value is changed based on one.

  In the said invention, the pressure change in the test object container sealed after open | release to air | atmosphere is measured in the 1st period and the 2nd period, and the pressure change in the test object container sealed after pressurizing to the test pressure is 1st period. Between the first period and the second period or after the second period, the first temperature compensation value is obtained from the measurement result of the first period, the second temperature compensation value is obtained from the measurement result of the second period, Based on the first temperature compensation value and the second temperature compensation value, a third temperature compensation value for the third period is calculated, and the measurement result of the third period is temperature compensated to determine whether there is a leak in the container to be inspected. When calculating the third temperature compensation value, the first temperature compensation value and the second temperature compensation value are weighted according to the magnitude of the examination pressure, the magnitude of the heat capacity of the examination target container, the magnitude of the heat transfer rate to the outside, the examination target container and the environment. And change based on at least one of the temperature differences. Since the relationship between the first temperature compensation value, the second temperature compensation value, and the third temperature compensation value becomes non-linear due to various factors, the non-linearity is approximated by adjusting the weighting factor to obtain the third temperature compensation value.

[2] As a pressure change in the inspection target container,
In the first measurement step and the second measurement step, a differential pressure between the reference container opened to the atmosphere or the reference container sealed after being opened to the atmosphere and the inspection object container sealed after being opened to the atmosphere is measured. And
In the third measuring step, a differential pressure between the reference container sealed after being pressurized to the inspection pressure and the inspection object container sealed after being pressurized to the inspection pressure is measured. The leak inspection method according to [1].

  In the said invention, the differential pressure | voltage of the pressure in a test object container and the pressure in a reference | standard container without a leak is measured.

[3] In the third temperature compensation value calculating step, when the third period is between the first period and the second period and the inspection pressure is a certain level or more, the heat capacity of the inspection object container is small. The weight of the first temperature compensation value is increased as the heat transfer coefficient to the outside increases or as the temperature difference between the container to be inspected and the environment increases [1] or The leak inspection method according to [2].

[4] In the third temperature compensation value calculating step, when the third period is between the first period and the second period, the weight of the first temperature compensation value is increased as the inspection pressure is higher. The leak inspection method according to any one of [1] to [3], wherein:

  In the above invention, the weight of the first temperature compensation value is increased with respect to the effect of the temperature rise due to the adiabatic compression at the time of pressurization in the third measurement step and the effect of the temperature drop due to the adiabatic expansion at the time of decompression. This is reflected in the third temperature compensation value.

[5] The first temperature compensation value, the second temperature compensation value, and the third temperature compensation value are pressure change amounts per unit time when there is no leakage. [1] to [4] ] The leak inspection method according to any one of the above.

  In the above invention, for example, a value obtained by dividing the pressure change amount obtained in the first measurement step by the length (time) of the first period is set as the first temperature compensation value.

[6] A leak inspection apparatus that inspects the presence or absence of leakage of a container to be inspected using the leak inspection method according to any one of [1] to [5].

  According to the leak inspection method and the leak inspection apparatus according to the present invention, even if the inspection pressure is high or the inspection is performed in a state where the temperature difference from the environmental temperature is large, the influence of the temperature fluctuation included in the measurement result is appropriately adjusted to the temperature. Can be compensated.

It is a figure which shows schematic structure and the flow of a test | inspection of the leak test | inspection apparatus based on this invention. It is a flowchart which shows the flow of the inspection process which a leak inspection apparatus performs. It is a figure which shows an example of the measurement result and temperature compensation value in a pre-correction process, a leakage test process, and a post-correction process. It is a figure which shows the outline | summary of the pressure change in a pre correction process, a leakage test process, and a post correction process. It is a figure which shows the temperature change inside a workpiece | work by the pressurization at the time of a leak test, and pressure reduction. It is a figure which shows the relationship between the pressure change rate of a pre-correction process, the pressure change rate of a post-correction process, the average, and the pressure change rate in the measurement period of a leak test process about various test pressures. It is a figure which shows the determination criterion of a weighting coefficient. It is a figure which shows the experimental result for confirming the effect of the correction | amendment by the temperature compensation value of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration and a flow of inspection of a leak inspection apparatus 10 according to the present invention. Hereinafter, all pressures are assumed to be gauge pressures. The leak inspection apparatus 10 is an apparatus that inspects for leaks in pipes (for example, heat exchangers) and containers (for example, hot water storage tanks) to be inspected. The container (or pipe line) to be inspected is the workpiece. Also, a container having the same shape and the same material as that of the workpiece and having been confirmed to have no leakage is taken as a master. The workpiece and master are different containers with the same mechanical and thermodynamic parameters. If the workpiece and the master are different containers having the same mechanical and thermodynamic parameters, the master will be larger if the workpiece is large, and as a result, a large space will be required as the location of the inspection device. There are cases where the master is small and the master is used with the same large size as that of the workpiece, and there is a case where the conversion coefficient is used when the small size is used. A method for dealing with such a case will be described later.

  The leak inspection apparatus 10 includes a pressurization source connection port 11, a work connection port 12, and a master connection port 13. The leak inspection apparatus 10 is connected to the pressurization source connection port 11 as an internal conduit. The first pipe 21 is bifurcated on the way into the second pipe 22 and the third pipe 23, and the other end of the second pipe 22 is connected to the work connection port 12. The other end of the pipe 23 is connected to the master connection port 13.

  A first on-off valve 31 is inserted in the first pipe 21. The second pipe 22 is provided with a second on-off valve 32, a first pressure gauge 41, and a third on-off valve 33 in the order of arrangement from the branch point with the first pipe 21 toward the work connection port 12. The third pipe 23 is provided with a fourth on-off valve 34, a second pressure gauge 42, and a fifth on-off valve 35 in the order of arrangement from the branch point with the first pipe 21 toward the master connection port 13.

  A differential pressure gauge 43 is connected between the second pipe 22 between the second on-off valve 32 and the third on-off valve 33 and the third pipe 23 between the fourth on-off valve 34 and the fifth on-off valve 35. Has been. An exhaust pipe 24 branches from the third pipe 23 at a predetermined position between the first on-off valve 31 and the fourth on-off valve 34, and an exhaust valve 38 is provided in the middle of the exhaust pipe 24. The end of the exhaust pipe 24 is an exhaust port and is open to the atmosphere.

  The leak inspection apparatus 10 includes an inspection processing unit 15 that performs inspection flow control, measurement, and leak determination based on a measurement result. The inspection processing unit 15 is a circuit mainly including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and the CPU executes processing according to a program stored in the ROM. Thus, the control, measurement and determination of the inspection operation in the leak inspection apparatus 10 are performed.

  A pressurized gas supply source 3 is connected to the pressurized source connection port 11 via an electropneumatic regulator 2. A pressure gauge 5 is connected to the pipe between the electropneumatic regulator 2 and the pressure source connection port 11. The electropneumatic regulator 2 functions to prevent the downstream side from exceeding the set pressure. The supply source 3 is installed outdoors, for example, and supplies pressurized gas from the supply source 3 to a machine or the like powered by other pressurized gas (for example, an air tool) (pipe line from the supply source 3 to the electropneumatic regulator 2) Reaches the pressure source connection port 11.

  A work 51 is connected to the work connection port 12. In this example, the work 51 is a through-type container having an inlet and an outlet (for example, a heat exchanger of a water heater). The inlet of the work 51 is connected to the work connection port 12, and the sixth on-off valve 36 is connected to the outlet. When the sixth on-off valve 36 is opened, the outlet of the work 51 is connected to the atmosphere and released to the atmosphere.

  A master 52 is connected to the master connection port 13. In this example, the master 52 is a penetrating container having an inlet and an outlet, like the work 51. The inlet of the master 52 is connected to the master connection port 13, and the seventh on-off valve 37 is connected to the outlet. When the seventh open / close valve 37 is opened, the outlet of the master 52 is opened to the atmosphere through the atmosphere.

  The work 51 undergoes the following processes from manufacturing to the end of inspection. Note that the master 52 is maintained in a state of being connected to the master connection port 13. The leak inspection apparatus 10 inspects new workpieces 51 one after another. After the work 51 is manufactured through the brazing process (P1), it is accumulated on the trolley and left for about 10 minutes, and settles to an environmental temperature of about + 10 ° C. (P2). After that, it is placed on the isothermal fan unit 6 that blows air and cooled by applying air for several minutes (P3). Then, it is attached to the leak inspection apparatus 10 and inspected (P4). When the inspection is completed, it is removed from the leak inspection apparatus 10 and sent to the next process (P5).

  FIG. 2 is a flowchart showing a flow of inspection processing performed by the leak inspection apparatus 10. After connecting the work 51 and the master 52 to the leak inspection apparatus 10 as shown in FIG. 1, all the on-off valves 32 to 38 except for the first on-off valve 31 are opened. Thereby, the workpiece | work 51 and the master 52 will be in the air release state (step S101). Thereafter, the exhaust valve 38 is closed, and in this state, the first opening / closing valve 31 is opened for a predetermined time (20 to 30 seconds) and then closed, thereby scavenging (pre-purge) the work 51 and the master 52 (step S102). The scavenging flow rate is, for example, about 50 to 100 liters in terms of atmospheric pressure.

  Thereafter, the sixth on-off valve 36 and the seventh on-off valve 37 are closed, the second on-off valve 32 and the fourth on-off valve 34 are closed, and the workpiece 51 and the master 52 are respectively sealed from the open state. A sealed space is set (step S103).

  Thereafter, a temperature compensation measurement step (referred to as a pre-correction step) is performed in which the differential pressure between the sealed space on the work 51 side and the sealed space on the master 52 side when left for a predetermined time is measured by the differential pressure gauge 43. (Step S104). The amount of change in the differential pressure measured in the pre-correction process (the difference between the differential pressure at the start of the measurement in the pre-correction process and the differential pressure at the end of the measurement in the pre-correction process) is ΔPt1, Let Ta be the measurement time of the change.

  Next, a leakage inspection process is performed. In the leakage inspection process, first, gas is pressurized and introduced to the workpiece 51 and the master 52 from the pressurized gas supply source 3 and pressurized to a predetermined inspection pressure (step S105: pressurization step). Specifically, the second on-off valve 32 and the fourth on-off valve 34 are opened to communicate the work 51 and the master 52, and then the first on-off valve 31 is opened to supply gas from the supply source 3 to the work 51 and the master 52. Introduce under pressure. Whether or not the target inspection pressure has been reached is confirmed by the pressure gauge 5, and when the target inspection pressure is reached, the first on-off valve 31 is closed. Thereafter, the second on-off valve 32 and the fourth on-off valve 34 are closed, and the work 51 and the master 52 are each set into independent sealed spaces pressurized to the inspection pressure (Pd) (step S105).

The amount of pressurization introduced at this time is 500 cc of the work 51 (master 52). For example, the volume of air at 20 ° C. and 500 kPa (G) is [T2] = 273.2 + 20 K [P2] = 101.3 + 500 kPa (abs) [V2] = 0.0005m ³ × 2, so, for example, it is extremely small compared to the scavenging flow rate and is about 6 liters in terms of atmospheric pressure ([T1] = 273.2 + 0 K [P1] = 101.3 + 0 kPa (abs) [V1] = 0.0059 m ³ ).

  Thereafter, after waiting for a settling period until the temperature change (pressure change) settles to some extent, a change in the differential pressure between the sealed space on the workpiece 51 side and the sealed space on the master 52 side is measured by the differential pressure gauge 43 (step S106: Measurement step). The amount of change in the differential pressure measured in the leak test process (difference between the differential pressure at the start of measurement in the leak test process and the differential pressure at the end of measurement in the leak test process) is ΔPr. The measurement time is Tr.

  Next, the work 51 and the master 52 are decompressed and released to the atmosphere (step S107: decompression step). Specifically, the second on-off valve 32 and the fourth on-off valve 34 are opened to allow the work 51 and the master 52 to communicate with each other, and then the exhaust valve 38 is opened to reduce the pressure and release to the atmosphere. At this time, the sixth on-off valve 36 and the seventh on-off valve 37 may be further opened.

  Thereafter, the exhaust valve 38 is closed (if the sixth open / close valve 36 and the seventh open / close valve 37 are opened when the atmosphere is opened, these are also closed), and the second open / close valve 32 and the fourth open / close valve 34 are closed, Each of 51 and the master 52 is set as an independent sealed space sealed from a state of opening to the atmosphere (step S108).

  Thereafter, a temperature compensation measuring step (referred to as a post-correction step) is performed in which the differential pressure between the sealed space on the workpiece 51 side and the sealed space on the master 52 side when left for a predetermined time is measured by the differential pressure gauge 43. (Step S109). The amount of change in the differential pressure measured in the post-correction process (the difference between the differential pressure at the start of measurement in the post-correction process and the differential pressure at the end of measurement in the post-correction process) is ΔPt2, and the differential pressure in the post-correction process The change measurement time is Tb.

  Next, the inspection processing unit 15 calculates the differential pressure per unit time in the pre-correction step from the change amount ΔPt1 of the differential pressure obtained in the pre-correction step and the length (Ta) of the measurement period in which the change amount ΔPt1 is measured. Is obtained as the first temperature compensation value H1. H1 = ΔPt1 / Ta

  Further, from the change amount ΔPt2 of the differential pressure obtained in the post-correction step and the length of the measurement period (time Tb) in which the change amount ΔPt2 was measured, the change amount of the differential pressure per unit time (the differential pressure) in the post-correction step Change rate) is obtained as the second temperature compensation value H2 (step S110). H2 = ΔPt2 / Tb

  Next, the inspection processing unit 15 sets the weighting coefficient (ratio) to be given to the first temperature compensation value H1 and the second temperature compensation value H2 at the time of starting the measurement of the magnitude of the inspection pressure at the time of leak inspection and the pre-correction process. This is determined based on the temperature difference between the workpiece 51 and the ambient temperature, the heat capacity of the workpiece 51, and the heat transfer coefficient of the workpiece 51 (step S111). The weighting factor given to the first temperature compensation value H1 is α, and the weighting factor given to the second temperature compensation value H2 is β. A method for determining the weighting coefficient will be described later.

  The first temperature compensation value H1 and the second temperature compensation value H2 are weighted according to the weighting factors α and β determined in step S111, and a weighted average of these is calculated. This calculation result is set as a temperature compensation value H3 for temperature compensation of the measurement result of the leakage inspection process (step S112). That is, H3 = (αH1 + βH2) / (α + β).

  The temperature compensation value H3 is an estimated value of the amount of change in the differential pressure per unit time based on the temperature variation during the measurement period (Tr) of the leakage inspection process.

  Next, the inspection processing unit 15 corrects the measurement result ΔPr of the leakage inspection with the temperature compensation value H3 to obtain a differential pressure ΔPs based on the leakage of the workpiece 51 (step S113).

Specifically, when the length of the measurement period when ΔPr is measured in the leakage inspection process is Tr, the pressure when the atmosphere is released is Pa, and the inspection pressure is Pd,
The differential pressure ΔPf for the temperature fluctuation included in the measurement result of the leak test is
ΔPf = H3 × Tr × Pd / Pa
It is obtained as Therefore, the differential pressure ΔPs based on leakage is
ΔPs = ΔPr−ΔPf
It is obtained as

  It is determined whether or not the differential pressure ΔPs due to leakage is greater than a predetermined reference value (step S114). If the differential pressure ΔPs due to leakage is greater than a predetermined reference value (step S114; Yes), it is determined that there is a leak. Then, this process ends. If the differential pressure ΔPs due to leakage is equal to or less than a predetermined reference value (step S114; No), it is determined that there is no leakage, and this processing is terminated.

  For example, if a container with a capacity of 980 ml is pressurized to 500 KPa, waits for the lapse of a set period, and is left for 30 seconds, the amount of change in the differential pressure before and after being left is temperature compensated and the value is ± 36 Pa or more. Is determined.

  FIG. 3 shows the temperature at the time of leakage inspection from the first temperature compensation value H1 based on the differential pressure ΔPt1 measured in the pre-correction step and the second temperature compensation value H2 based on the differential pressure ΔPt2 measured in the post-correction step. The compensation value H3 is estimated, and the pressure difference ΔPf based on temperature fluctuation is removed from the pressure difference ΔPr measured in the leak test, and the pressure difference ΔPs due to leakage (mass change) is derived. ing.

  Next, a method for determining a weighting factor will be described.

  FIG. 4 shows an outline of a change in pressure difference between the workpiece 51 and the master 52 (pressure in the workpiece 51−pressure in the master 52 = pressure in the workpiece 51 with reference to the master 52) (hereinafter, pressure change). Yes. In this figure, the pressure change in the pre-correction step and the post-correction step is indicated by straight lines having the first temperature compensation value H1 and the second temperature compensation value H2 as slopes. In the leak inspection process, a rapid pressure change is made during the settling period after pressurizing to the inspection pressure, and when the pressure change gradually becomes gentle, a measurement step for measuring the pressure change is performed (Tr).

  If there is no settling period (Ts2 = 0) before the post-correction process, the degree of change in the differential pressure between the work 51 and the master 52 due to the influence of temperature in the entire leakage inspection process (settling period Ts1 + measurement step Tr) ( Hereinafter, the pressure change rate can be expressed by an average value of the first temperature compensation value H1 and the second temperature compensation value H2. However, the pressure change in the leakage inspection process is suddenly generated in the settling period (Ts1) of the leakage inspection process and is gentle in the measurement step (Tr) of the leakage inspection process, so the pressure change rate in the measurement step (Tr). Is smaller than the average value of the first temperature compensation value H1 and the second temperature compensation value H2 (element 1).

  To explain this point in detail, the master reaches a substantially predetermined temperature (for example, a substantially predetermined temperature at which the temperature has dropped from the surrounding environment) after a plurality of inspections (the temperature with the workpiece 51 at room temperature depending on the case). In order to become a difference problem, a plurality of workpieces 51 may be rotated to cope with the temperature difference problem. However, when the workpiece 51 to be inspected is hotter than the master 52 as in the present application (for example, even if cooling by air cooling is performed after argon welding but still has preheating), the leakage inspection process In the settling period (Ts1), the temperature of the work 51 is larger than that of the master 52 (because both of them are not greatly lowered in temperature but fall in a state where the temperature drop rates of the two are greatly different), The amount of change in the differential pressure between the two is abrupt.

  Since the temperature difference between the master 52 and the work 51 becomes close after the temperature of the work 51 has dropped greatly, the temperature drops (both of them are not the same temperature drop, but the temperature drop rate between the two is close) In order to descend), in the measurement step (Tr) of the leakage inspection process, the amount of change in the differential pressure between the two is moderate. Thus, since the change in the differential pressure between the two in the leakage inspection process is not the same in the first half and the second half, the pressure change rate cannot be expressed by the average value of the first temperature compensation value H1 and the second temperature compensation value H2.

  In step S102, the work 51 and the master 52 are scavenged (pre-purge). However, since the work 51 to be inspected is hotter than the master 52, the gas in the work 51 expands even during the scavenging (pipe resistance is reduced). And the gas density in the work 51 and the master 52 sealed in step S103 is different (even in the work 51, the third on-off valve 33 and the second There is a difference in gas density in the vicinity of the 6 on-off valve 36). In the pressurizing step of step S105, the work 51 and the master 52 are pressurized and filled to the same pressure. Even if the work 51 and the master 52 have the same volume, the initially sealed volumes are different (the same). Since the volume is different but the volume is different when converted to the same temperature), naturally, a differential pressure is generated after a predetermined time, and the filling amount is also different. As a result, due to adiabatic compression, which will be described later, there is a difference in the degree of internal temperature rise between the work 51 and the master 52 (the work 51 has a larger amount of filling than the master 52 because the filling amount is larger = master. The gas in the work 51 becomes an independent sealed space pressurized to the inspection pressure (Pd) in a state filled with a gas having a low gas density with respect to 52. In this way, temperature fluctuations (mainly in the leak inspection) The difference in the gas density in the work 51 sealed in step S103 and the master 52 affects the leakage inspection stage of the measurement step in step S106).

  Since it is impossible to measure the gas temperature (density) in the work 51 sealed in step S103, it is natural to estimate characteristics when the temperature of the object decreases (for example, simple temperature decrease characteristics such as exponential decay). It is impossible to specify the starting temperature to be estimated), and therefore it is also impossible to estimate the amount of change in the differential pressure between the two in the leak test at the measurement step in step S106. It is also affected by the quality of air used for scavenging (for example, the influence of specific heat such as argon partial pressure and humidity). The result affected by the starting temperature or the like appears as the amount of change in the differential pressure between the two at the measurement step (Tr). For example, the gas temperature difference between the master 52 and the work 51 is large (the gas temperature in the work 51 is The first temperature compensation value H1 is the same when the humidity is low and the argon partial pressure is high, and when the gas temperature difference between the master 52 and the work 51 is small but the humidity is high or the argon partial pressure is low. Therefore, the temperature cannot be compensated only by the first temperature compensation value H1.

  This is because, for example, as long as the first temperature compensation value H1 is not zero, the filling amount of the work 51 and the master 52 in step S105 is different (for example, the filling amount of the work 51 is larger), and the work 51 in adiabatic compression. This is because there is a difference in the degree of internal temperature rise between the master 52 and the master 52 (which affects the amount of change in the differential pressure between the two at the measurement step (Tr)) (in other words, when a plurality of unknowns are included, The unknown cannot be obtained unless a set of a plurality of continuous cubes is given. However, in this application, in order to compensate the temperature when the work 51 to be inspected is hotter than the master 52, two or more, for example, at least The first temperature compensation value H1, the second temperature compensation value H2, and weighting are used.) In the case where a pressure change in the inspection target container sealed after pressurizing the inspection target container to a predetermined inspection pressure is measured in a third period after the second period, at least the first temperature compensation value H1. From the second temperature compensation value H2, it is necessary to calculate the difference in gas density between the work 51 and the master 52 sealed in step S103.

  FIG. 5 shows the temperature change inside the workpiece in the leakage inspection process. The internal temperature of the work 51 rises due to adiabatic compression when pressurizing to the inspection pressure (420 KPa in this example), and then changes so as to gradually decrease after abruptly decreasing. The period until the internal temperature after pressurization is settled to some extent is set at regular intervals, and the pressure change is measured over a predetermined period thereafter (measurement step). After the measurement is completed, the pressure is reduced to release the atmosphere. Due to the adiabatic expansion at this time, the internal temperature of the work 51 rapidly decreases, and thereafter gradually changes to the environmental temperature. Accordingly, when the inspection pressure is high, as shown by the broken line in FIG. 5, the ratio that the residual heat of the work 51 is offset by the heat absorption due to the reduced pressure increases, so that the differential pressure ΔPt2 measured in the post-correction process is increased. Influencing (element 2).

  To explain this point in detail, the heat absorption due to the reduced pressure is greatly increased by the reduced pressure speed (the reduced pressure speed depending on the piping distance between the workpiece 51 and the end of the air release end of the exhaust valve 38 = the outlet piping resistance from the workpiece 51). In contrast, the greater the pressure reduction rate (the shorter the outlet piping distance), the greater the amount of heat absorption (the piping distance and piping resistance are also factors of the inspection pressure). When the amount of heat absorption is large, the settling time TS2 apparently becomes longer and the heat dissipation amount at the internal temperature of the work 51 is increased.

  By the way, when the work 51 is small, it can be inspected by placing it next to the leak inspection apparatus 10 (for example, on the inspection table), but the work 51 is a large tank such as a 370 liter used in an electric water heater or the like. In such a case, the leak inspection apparatus 10 cannot be placed right next to the leak inspection apparatus 10 and is inspected on the nearby ground. Of course, there are many cases where the outlet side pipe resistance is different for each inspection object (by the size of the work 51). If the workpiece 51 and the master 52 have the same temperature before inspection (if the gas density in the workpiece 51 and the master 52 sealed in step S103 does not differ and the outlet piping distance is the same), the difference Although there is no effect on the pressure ΔPt2, if the temperature is not the same before the inspection, the side where the temperature difference with the environmental temperature appears greatly may be reversed due to the endothermic effect due to the reduced pressure (the side where the temperature difference appears larger is the pressure change). Since the ratio increases, it affects the differential pressure ΔPt2 measured in the post-correction process.

  In FIG. 5, the temperature rise due to adiabatic compression at the time of pressurization and the temperature drop due to the endothermic amount at the time of pressure reduction (change temperature: X axis, change degree: area) are greatly different. For example, it is pressurized over time from a supply source 3 placed outdoors over a long pipe distance (pipe resistance is large), but when the pressure is reduced, the pressure is reduced in a short time (pipe resistance is small) and the pressure is reduced in a short time. (In other words, the electropneumatic regulator 2 (corresponding to the piping resistance) is passed during pressurization, and the electropneumatic regulator 2 is not passed during depressurization).

  As described above, the difference between the gas density in the workpiece 51 and the master 52 sealed in step S103 affects the leakage inspection stage of the measurement step in step S106. The piping resistance from the work 51 (or the electropneumatic regulator 2 to the master 52) is also involved. From the electropneumatic regulator 2 to the work connection port 12, the manufacturer of the leak inspection apparatus 10 is involved, and from the work connection port 12 to the work 51, the manufacturer of the leak inspection apparatus 10 that inspects the work 51 is involved. It is preferable that the manufacturer of the leak inspection apparatus 10 makes it possible for the manufacturer of the apparatus 10 to change the weighting according to the piping and other usage conditions.

  In detail, when the workpiece 51 is small, it can be inspected by placing it next to the leak inspection apparatus 10 (for example, on the inspection table). However, the workpiece 51 is 370 liters used in, for example, an electric water heater or the like. In the case of such a large tank, it is not possible to place it next to the leak inspection apparatus 10, and inspection is performed on the nearby ground. Naturally, the piping from the workpiece connection port 12 to the workpiece 51 is appropriately set by the manufacturer of the leak inspection apparatus 10, so that the piping distance (hereinafter referred to as the inlet side piping resistance) is different. In the case where the work 51 sealed in step S103 has a lower sealed gas density, even if the work 51 and the inlet side pipe to the master 52 are the same, if both are short (the inlet side pipe resistance is small), the case is long. As compared with the pressure difference ΔPt2, the pressure difference is greatly affected. Accordingly, the shorter the inlet piping distance (the smaller the inlet piping resistance), the greater the difference in the degree of internal temperature rise between the work 51 and the master 52 in adiabatic compression. Therefore, the inlet piping distance must be taken into account for weighting. (For example, it is necessary to change the weighting table or change the standard (center) value according to the conditions under which the leak inspection apparatus 10 is installed).

  More specifically, when the inspection pressure is low, the pressure change rate in the leakage inspection process is more gradual (for example, the pressure change) than the pressure change rate H1 in the pre-correction process in FIG. 4 (step 104). The rate of pressure change at the measurement step is likely to be smaller than (H1 + H2) / 2 (with a gradient that emphasizes the pressure change rate H2 in the post-correction step). On the other hand, when the inspection pressure is high, the pressure change rate in the leakage inspection process, for example, may be steeper than the pressure change rate H1 in FIG. 4 (step 104). In some cases, the pressure change rate in the measurement step is larger than (H1 + H2) / 2 (a gradient that emphasizes the pressure change rate H2 in the previous correction step) (see the gray line in FIG. 4).

  In step S105, the flow rate and flow rate of the pressurizing gas are changed, or the supply pressure of the work connection port 12 is changed and the inlet side pipe resistance, or the pressure change pressure of the work 51 and the master 52 is changed (for example, Since the internal pressure of the work 51 and the master 52 is increased in step S105 and the flow velocity is decreased, the internal temperature rise of the work 51 and the master 52 in the adiabatic compression is not considered from the mere pressure. It is necessary to obtain the difference in degree by calculation (according to the piping and other conditions used by the manufacturer of the leak inspection apparatus 10).

  FIG. 6 conceptually shows the relationship between the magnitude of the inspection pressure and the pressure change rate in each process. When the inspection pressure is small, for example, the influence of the element 2 is small and the influence of the element 1 is large. On the other hand, when the inspection pressure increases, for example, the influence of the element 1 does not change, but the influence of the element 2 increases.

  For example, in FIG. 6, when the inspection pressure is small, the average value of the pressure change rate H1 (−2) in the pre-correction process and the pressure change rate H2 (−1.4) in the post-correction process is −1.7. However, since the pressure change rate H3 in the measurement period (measurement step) of the actual leakage inspection process is −1.6, the influence of the pressure change rate H2 in the post-correction process is large. Therefore, when the temperature compensation value H3 in the measurement period of the leakage inspection process is obtained by the weighted average of the first temperature compensation value H1 and the second temperature compensation value H2, the weighting factor β given to H2 is obtained from the weighting factor α given to H1. Enlarge. In this example, the ratio of α: β is 1: 2.

  When the inspection pressure is medium, the inspection pressure is higher than when the inspection pressure is small. Therefore, the influence of the element 2 appears, and the residual heat of the work 51 is slightly offset by the heat absorption due to the reduced pressure. For this reason, the difference between the workpiece 51 and the environmental temperature at the start of the post-correction process becomes small and the temperature change becomes gradual, and the pressure change rate in the post-correction process is -1.2. In this case, the average value of the pressure change rate H1 (−2) in the pre-correction process and the pressure change rate H2 (−1.2) in the post-correction process is −1.6, and the measurement period of the actual leak inspection process This corresponds to the pressure change rate H3. Therefore, the weighting factor α given to the first temperature compensation value H1 and the weighting factor β given to the second temperature compensation value H2 may be 1: 1.

  When the inspection pressure is large 1, the inspection pressure is further increased, and accordingly, the influence of the element 2 appears strongly, and the rate at which the residual heat of the work 51 is offset by the heat absorption due to the reduced pressure increases. Therefore, the pressure change rate in the post-correction process is −1.0. In this case, the average value of the pressure change rate H1 (−2) in the pre-correction process and the pressure change rate H2 (−1.0) in the post-correction process becomes −1.5, and the measurement period of the actual leak inspection process The pressure change rate at H3 is smaller than (−1.6). Therefore, the weighting factor α given to the first temperature compensation value H1 is made larger than the weighting factor β given to the second temperature compensation value H2. Specifically, in this example, the ratio of α: β is 3: 2.

  In the case where the inspection pressure is the highest (large 2), the influence of the element 2 appears more strongly, so that the rate at which the residual heat of the work 51 is offset by the heat absorption due to the reduced pressure is further increased. Therefore, the pressure change rate in the post-correction process is −0.4. In this case, the average value of the pressure change rate H1 (−2) in the pre-correction process and the pressure change rate H2 (−0.4) in the post-correction process becomes −1.2, and the measurement period of the actual leak inspection process It is considerably smaller than the pressure change rate H3 (−1.6). Therefore, the weighting factor α given to the first temperature compensation value H1 is considerably larger than the weighting factor β given to the second temperature compensation value H2. Specifically, in this example, the ratio of α: β is 3: 1.

  As described above, the weight given to the first temperature compensation value H1 when obtaining the temperature compensation value H3 for temperature compensation of the measurement result of the leak test by the weighted average of the first temperature compensation value H1 and the second temperature compensation value H2. By setting the ratio of the coefficient α and the weighting factor β given to the second temperature compensation value H2 in consideration of the influence of the element 1 and the element 2, it is possible to appropriately compensate the temperature of the measurement result of the leakage inspection process. it can.

  Here, the influence of the element 1 becomes more prominent as the temperature difference between the work 51 and the environmental temperature is larger, the heat capacity of the work 51 is smaller, and the heat transfer coefficient of the work 51 is larger. On the other hand, the influence of the element 2 becomes more prominent as the temperature difference between the workpiece 51 and the environmental temperature is larger, the heat capacity of the workpiece 51 is smaller, and the heat transfer coefficient of the workpiece 51 is larger. The influence of the element 2 increases as the inspection pressure increases.

  Therefore, when the inspection pressure is low, the weight coefficient given to the second temperature compensation value H2 is larger as the temperature difference between the workpiece 51 and the ambient temperature is larger, the heat capacity of the workpiece 51 is smaller, and the heat transfer coefficient of the workpiece 51 is larger. β is set larger than the weighting factor α given to the first temperature compensation value H1. On the other hand, when the inspection pressure is high, the weight coefficient given to the first temperature compensation value H1 is larger as the temperature difference between the workpiece 51 and the environmental temperature is larger, the heat capacity of the workpiece 51 is smaller, and the heat transfer coefficient of the workpiece 51 is larger. α is made larger than the weighting coefficient β given to the second temperature compensation value H2.

  Based on the above, weighting factors are given according to the determination criteria as shown in FIG. FIG. 4A shows the relationship between the magnitude of the inspection pressure, the magnitude of the heat capacity of the work 51, and the weighting factors given to the first temperature compensation value H1 and the second temperature compensation value H2. When the inspection pressure is low, the weight coefficient α given to the first temperature compensation value H1 is increased and the weight coefficient β given to the second temperature compensation value H2 is decreased as the heat capacity of the work 51 is increased. When the inspection pressure is high, the weighting coefficient α given to the first temperature compensation value H1 is reduced and the weighting coefficient β given to the second temperature compensation value H2 is increased as the heat capacity of the work 51 is increased. Further, the higher the inspection pressure, the larger the ratio of the weight coefficient β to the weight coefficient α even if the heat capacity is the same.

  FIG. 7B shows the relationship between the magnitude of the inspection pressure, the magnitude of the temperature of the workpiece 51 and the environmental temperature at the start of the previous process, and the weighting coefficient applied to the first temperature compensation value H1 and the second temperature compensation value H2. Is shown. When the inspection pressure is low, the weighting coefficient α applied to the first temperature compensation value H1 is decreased and the weighting coefficient β applied to the second temperature compensation value H2 is increased as the temperature difference is increased. When the inspection pressure is high, the weighting coefficient α applied to the first temperature compensation value H1 is increased and the weighting coefficient β applied to the second temperature compensation value H2 is decreased as the temperature difference is increased. Further, as the inspection pressure is higher, the ratio of the weighting factor α to the weighting factor β is increased even if the temperature difference is the same.

  FIG. 4C shows the relationship between the magnitude of the inspection pressure, the magnitude of the heat transfer coefficient of the work 51, and the weighting coefficients given to the first temperature compensation value H1 and the second temperature compensation value H2. When the inspection pressure is low, the weighting coefficient α given to the first temperature compensation value H1 is reduced and the weighting coefficient β given to the second temperature compensation value H2 is increased as the heat transfer coefficient is increased. When the inspection pressure is high, the weighting coefficient α given to the first temperature compensation value H1 is increased and the weighting coefficient β given to the second temperature compensation value H2 is decreased as the heat transfer coefficient is increased. Further, as the inspection pressure is higher, the ratio of the weighting coefficient α to the weighting coefficient β is increased even if the heat transfer coefficient is the same.

  It is desirable to determine the weight (ratio) of the first temperature compensation value H1 and the second temperature compensation value H2 in consideration of all of the inspection pressure, the heat capacity, the temperature difference from the environmental temperature, and the heat transfer coefficient. The weights of the first temperature compensation value H1 and the second temperature compensation value H2 may be determined based on at least one of the following. If the inspection pressure is always high, a weighting coefficient corresponding to the heat capacity, the temperature difference from the environmental temperature, and the heat transfer coefficient may be used on the assumption.

  If this point is explained in full detail, for example, there are a hot water heater No. 16 and a hot water heater No. 24 according to the capability. In this water heater, there is a sensible heat exchanger (for example, 80% exchange efficiency) for exchanging hot water for 25 degup and 16 liters per minute, and a sensible heat exchanger for exchanging gas for liquid heat for 25 degup and 24 liters per minute (for example, The exchange efficiency is 80%), and the two have substantially the same heat transfer coefficient. When inspecting while mixing the two, the inspection pressure, the heat capacity, the temperature difference from the environmental temperature, and the heat transfer coefficient are substantially the same as the inspection pressure, the temperature difference from the environmental temperature, and the heat transfer coefficient. It is possible to perform the mixed inspection only by changing the weight (ratio) of the first temperature compensation value H1 and the second temperature compensation value H2 according to the difference.

  FIG. 8 is a graph showing experimental results for confirming the effect of correction by the temperature compensation value. In this experiment, leakage inspection was performed on 549 980 ml containers without leakage. The graph is a frequency distribution showing variation in results. The graph before the correction shows the variation in the measurement result when the temperature is not corrected, and the graph after the correction shows the variation in the result obtained by correcting the measurement result with the temperature compensation value H3.

  Before the correction, the measurement time of 30 seconds may vary to around 200 Pa. When 36 Pa is set as a threshold value for determining that there is no leakage, 36% of 549 containers without leakage are erroneously determined as having leakage. On the other hand, after correcting the measurement result of the leak test with the temperature compensation value H3, the frequency of appearance is concentrated in the vicinity of the differential pressure of 0, although there is variation up to about 90 Pa. After correction, when 36 Pa is set as a threshold value for determining that there is no leakage, only about 3% of the 549 containers without leakage are erroneously determined to be leaking, and it can be seen that the determination accuracy is increased.

  To elaborate on this point, from the measurement results of the container leak inspection without leakage, the weighting coefficient corresponding to the inspection pressure, heat capacity, temperature difference from the ambient temperature, and heat transfer coefficient is obtained by calculation, and the determination accuracy is based on this. The weight (ratio) of the first temperature compensation value H1 and the second temperature compensation value H2 to be increased may be obtained (correction is performed), the test pressure, the heat capacity, the temperature difference from the ambient temperature, and the heat transfer coefficient. , And the weight (ratio) of the first temperature compensation value H1 and the second temperature compensation value H2 that directly increases the determination accuracy (the mode value increases) is obtained by, for example, calculation (for example, discrete differentiation). For example, a calculation (for example, a regression calculation) may be performed so as to change (correct) the weight (ratio) between the first temperature compensation value H1 and the second temperature compensation value H2 according to the heat capacity difference.

  By the way, in the sensible heat exchanger mentioned above, each part may be brazed and taken out from the furnace in the furnace, but the temperature at which the brazing material can be melted is constant (the furnace temperature is constant). The temperature difference from the ambient temperature is small in summer and large in winter. On the other hand, the room temperature (one of the environmental temperature factors) where the leak inspection is measured is changed so that it is not burdened by the inspector according to the office hygiene standard rules. Accordingly, the weight (ratio) between the first temperature compensation value H1 and the second temperature compensation value H2 may be changed (corrected). Thereby, it is possible to change the inspection pressure, the heat capacity, the temperature difference from the environmental temperature, and the heat transfer rate while maintaining a state in which the determination accuracy is high.

  In the leakage inspection process, the workpiece 51 and the master 52 are pressurized to a predetermined inspection pressure, and at this time, the gas in the workpiece 51 and the master 52 is adiabatically compressed and the temperature rises. In other words, the temperatures of the workpiece 51 and the master 52 that have fallen during the pre-correction process rise once before starting the measurement of the differential pressure in the leakage inspection process. For this reason, the temperature of the work 51 and the master 52 that has decreased from the start of the pre-correction process to the start of pressurization in the leakage inspection process rises again due to the pressurization, and the work 51 and the master 52 are disclosed when the measurement step of the leakage inspection is disclosed. The temperature of the gas inside falls again from the high temperature.

  That is, the temperature difference between the workpiece 51 and the environmental temperature at the start of the measurement step of the leakage inspection process and the temperature difference between the master 52 and the environmental temperature are both larger than at the end of the pre-correction process, but to the extent that they are larger. Since a difference occurs (refer to [0059] to [0071] for details of the reason), the differential pressure between the workpiece 51 and the master 52 (the amount of change in the differential pressure) is affected. Therefore, the weight of the first temperature compensation value H1 when determining the temperature compensation value H3 is increased in consideration of the increase difference in the temperature difference between the internal temperature of the work 51 and the master 52 and the environmental temperature based on the temperature rise due to the adiabatic compression. To do. If the settling time is the same, the temperature difference at the start of the measurement step increases as the inspection pressure increases. Therefore, the weight of the first temperature compensation value increases as the inspection pressure during the leak inspection increases. As a result, the temperature rise due to adiabatic compression can be taken into account, and the measurement result at the time of leak inspection can be appropriately temperature compensated.

  Further, in the pressure reduction step of the leakage inspection process, heat absorption due to pressure reduction occurs in the measurement step. To explain this point in detail, the heat absorption due to depressurization varies greatly depending on the depressurization speed (the depressurization speed that depends on the piping distance between the work 51 and the end of the air release end of the exhaust valve 38). The shorter the side piping distance), the greater the amount of heat absorbed. When the amount of heat absorption is large, the settling time TS2 apparently becomes longer and the heat dissipation amount at the internal temperature of the work 51 is increased. By the way, when the work 51 is small, it can be inspected by placing it next to the leak inspection apparatus 10 (for example, on the inspection table), but the work 51 is a large tank such as a 370 liter used in an electric water heater or the like. In such a case, the leak inspection apparatus 10 cannot be placed right next to the leak inspection apparatus 10 and is inspected on the nearby ground. Therefore, the degree of heat absorption due to the reduced pressure depends not only on the inspection pressure (pressure difference from the atmospheric pressure at the time of reduced pressure) but also on the outlet side piping distance (pipe resistance) to the release end that releases the pressure in the work 51. .

<Modification>
The leakage inspection process was performed between the pre-correction process and the post-correction process, but the correction process for obtaining the first temperature compensation value H1 (as indicated by the gray line in FIG. Used step) and a correction step for obtaining the second temperature compensation value H2 (as shown by the gray line in FIG. 4), the differential pressure changes more slowly than the location sampled to obtain the first temperature compensation value H1. After performing the process using the location to be performed), the leakage compensation process may be performed to obtain the temperature compensation value H3.

  When the leakage inspection process is performed between the pre-correction process and the post-correction process, the temperature compensation value H3 is obtained by interpolating the first temperature compensation value H1 and the second temperature compensation value H2 at a predetermined ratio (weighting). On the other hand, when the leakage inspection process is performed after the correction process for obtaining the first temperature compensation value H1 and the correction process for obtaining the second temperature compensation value H2 as described above, the first temperature compensation value H1. And the second temperature compensation value H2 are extrapolated at a predetermined ratio (weighting) to obtain the temperature compensation value H3.

  For example, when the time between the first correction step and the second correction step is equal to the time of the second correction step and the leakage inspection step (for example, zero), the first time obtained in the first correction step The relationship between the temperature compensation value H1 and the second temperature compensation value obtained in the second correction step and the temperature compensation value H3 at the time of leakage inspection is as follows: if the change of the temperature compensation value is linear, H3 = −H1 + 2 × H2. Become. Therefore, a weighting coefficient is given to this, H3 = −αH1 + 2βH2, and α and β may be determined according to the nonlinearity. In this case, since the second correction process is performed before the leakage inspection process, the second correction process is not affected by the temperature drop due to the adiabatic expansion at the time of decompression. In the case of extrapolation, the magnitude relationship of weighting is reversed from that in the case of interpolation. Therefore, the smaller the heat capacity of the work 51, the greater the temperature difference, and the greater the heat transfer coefficient, the larger α and the smaller β.

  By the way, a gas higher than the environmental temperature is often supplied from the pressurized gas supply source 3. Therefore, the leakage inspection apparatus 10 is reached from the supply source 3 while radiating heat, for example. On the other hand, what is determined to have about 3% leakage shown in FIG. 8 is inspected again in the retry process, but naturally the removal and attachment process is omitted, and for example, S115 is followed by S101. Therefore, since the inspection is performed again while the heat radiation of the gas reaching the leak inspection device 10 is small while radiating heat from the supply source 3, the weight may be changed depending on whether or not the reinspection is performed.

  Further, for example, when inspecting when the supply of pressurized gas is large from a supply source 3 to a machine powered by another pressurized gas or when inspecting when the supply of pressurized gas is small, the leakage inspection apparatus 10 is radiated from the supply source 3 while radiating heat. Since the inspection is performed while the degree of heat radiation of the gas to reach is small, the weighting may be changed according to the operating status of the equipment using other pressurized gas as power.

  Furthermore, although the case where the workpiece 51 to be inspected is inspected while the temperature is high has been described, the present application is also effective when the inspection is performed while the temperature is substantially close to the environmental temperature, such as a gas meter. For example, the weighting may be changed depending on whether the inspection is performed when the amount of pressurized gas supplied to a machine or the like powered by another pressurized gas from the supply source 3 is large and when the amount is small. For example, the weight may be changed according to the quality of the gas supplied from the supply source 3.

  For example, when the inspection room is a narrow temperature-controlled room where only the work 51, the master 52, the leak inspection apparatus 10, etc. can be arranged, the work 51 is set in the leak inspection apparatus 10 by hand and the inspection room door is closed. When performing the inspection, the room temperature of the inspection room fluctuates depending on the body temperature of the inspector when the work 51 is set, and the effect appears strongly in ΔPt1, but there is almost no effect in ΔPr, and no effect in ΔPt2. (Influence degree: ΔPr>...> ΔPr> ΔPt2). Even in such a case, if the weighting can be changed due to the temperature difference from the environment (environmental temperature fluctuation due to body temperature due to inspector work in the inspector), for example, the non-defective product is the first time (influence: ΔPr>... > ΔPr> ΔPt2), it is easy to misdetermine that it is defective. If it is determined that the second inspection (influence: ΔPr≈ΔPr≈ΔPt2) is acceptable, the weighting is changed and the first inspection is performed. The inspection time can be shortened by reducing the number of erroneous determinations. That is, when changing the weighting based on the magnitude of the temperature difference between the workpiece 51 and the environment, there are cases where there is a main cause of the temperature difference on the workpiece 51 side as inspecting the hot workpiece 51, and the environment as described above. There is a case where there is a main cause of the temperature difference on the side, and it is not necessary to ask the location of the cause, and if the weight can be changed, the inspection time can be shortened.

  In this regard, when the object to be inspected is an object made by water jet cutting or an object to be fitted (for example, metal seal) using liquid nitrogen or the like, the work 51 is in a state where the temperature is lower than the environmental temperature. Will be inspected. More specifically, when the work 51 is colder than the master 52, the temperature of the work 51 is larger than that of the master 52 during the settling period (Ts1) in the leakage inspection process. The amount of change in the differential pressure becomes abrupt, and when the measurement step (Tr) for measuring the pressure change is performed, the pressure change becomes gradual. Therefore, the present application is effective even in such a case.

  Furthermore, when inspecting an object having a common inlet and outlet, for example, a tank-like tank manufactured by argon welding or the like, scavenging may not be performed sufficiently even if the scavenging time is extended, It is easy to inspect with argon remaining in the tank during welding. That is, since the workpiece 51 and the master 52 are easily inspected in a state where the gas composition is different, whether or not the workpiece 51 and the master 52 are manufactured by, for example, argon welding or the like in the gas supplied from the supply source 3. The weighting may be changed in consideration of whether the argon used in the argon welding is not mixed, or if it is mixed, how much argon is mixed = situation such as argon partial pressure).

  Furthermore, if the workpiece 51 and the master 52 are different containers having the same mechanical and thermodynamic parameters, the master 52 is larger when the workpiece 51 is large, and as a result, a large space is required as a place for possessing the inspection apparatus. Therefore, there is a case where the master 52 is made small, and the master 52 uses the same large size as that of the work 51, and the conversion coefficient is used when the small size is used. Even in such a case, it is the same that the gas having different gas density is sealed in the hot work 51 and the small-sized master 52 at room temperature sealed in step S103, and the pressure is increased in step S105. Sometimes the internal temperature rise of the workpiece 51 and the master 52 due to adiabatic compression is the same in that the workpiece 51 sealed with air having a low gas density generates more heat than the master 52. The same. However, paying attention to the inlet side pipe resistance, for example, when inspecting a 370 liter hot water storage tank (work 51), the small master 52 can be placed on the same inspection table as the leak inspection apparatus 10 (small inlet side pipe resistance = On the other hand, the large workpiece 51 cannot use the short piping used for the small master 52 (if the workpiece 51 and the master 52 are of the same size, the input side piping resistance is reduced). Although the workpiece 51 and the master 52 can be connected to the leak inspection apparatus 10 with the same piping, the purpose of using the small master 52 is often to narrow the inspection location, so the piping with the same inlet side piping resistance is often not used. ), Such an input side pipe resistance (or an output side pipe resistance) may also be dealt with by weighting.

  Further, the weighting (weighting coefficient) may be not only a positive value but also a negative value, or both may be negative values.

  Furthermore, two or more correction processes for measurement when the atmosphere is open may be performed, and the number of weighting coefficients corresponding to the number of correction processes may be provided. Furthermore, the measurement pressure in the pre-correction process and the post-correction process may be other than the pressure in the leakage inspection process, and a minute pressurization step is inserted in the pre-correction process or the post-correction process to obtain the respective pressure change rates. Anyway.

By the way, for example, when an argon welded object is to be inspected, the inspection air introduction port (compressor air supply port) may be near the place where the argon welding is being performed. Argon may be mixed with the working air. In addition, when the test air inlet is in the north, even when the humidity is low, the humidity of the test air changes between when there is no wind and when the wind blows. There is.
Therefore, in this way, the quality of air to be filled may be different for each inspection (each work). Therefore, in this application, the quality of the air to be filled is assumed to be substantially the same (using the fact that the quality of the air enclosed in the successive pre-correction process, leak inspection process, and post-correction process is approximate), and pressurization This is characterized in that the pressure change rate (ratio of H1 and H2) in the leakage inspection process is determined based on the pressure change rates in a plurality of processes (for example, the pre-correction process and the post-correction process) having different conditions.

  The embodiment of the present invention has been described with reference to the drawings. However, the specific configuration is not limited to that shown in the embodiment, and there are changes and additions within the scope of the present invention. Are also included in the present invention.

  In the embodiment, an example in which the differential pressure between the workpiece 51 and the master 52 is measured as the leak inspection apparatus 10 is shown, but a configuration in which the pressure of the workpiece 51 is directly measured may be used.

  The present invention is not limited to a leak inspection apparatus, and includes a leak inspection method.

DESCRIPTION OF SYMBOLS 2 ... Electropneumatic regulator 3 ... Supply source of pressurized gas 5 ... Pressure gauge 6 ... Isothermal fan unit 10 ... Leak inspection apparatus 11 ... Pressurization source connection port 12 ... Work connection port 13 ... Master connection port 15 ... Inspection processing part DESCRIPTION OF SYMBOLS 21 ... 1st piping 22 ... 2nd piping 23 ... 3rd piping 24 ... Exhaust pipe 31 ... 1st on-off valve 32 ... 2nd on-off valve 33 ... 3rd on-off valve 34 ... 4th on-off valve 35 ... 5th on-off valve 36 ... 6th open / close valve 37 ... 7th open / close valve 38 ... Exhaust valve 41 ... 1st pressure gauge 42 ... 2nd pressure gauge 43 ... Differential pressure gauge 51 ... Work 52 ... Master H1 ... 1st temperature compensation value H2 ... 2nd temperature compensation Value H3: Third temperature compensation value ΔPt1: Differential pressure measured in the previous correction process ΔPt2: Differential pressure measured in the post-correction process ΔPr: Differential pressure measured in the measurement step of the leakage inspection process ΔPs: ΔPr Differential pressure due to leakage ΔPf ... Pressure difference due to Pd ... Inspection pressure Pa ... Pressure at atmospheric release Ta ... Measurement time of differential pressure change in pre-correction process Tb ... Measurement time of differential pressure change in post-correction process Tr ... Measurement time of differential pressure change in leak inspection process

Claims (6)

A leak inspection method for inspecting whether there is a leak in a container to be inspected,
A first measurement step of measuring a pressure change in the inspection target container sealed after being opened to the atmosphere in a first period;
A second measurement step of measuring a pressure change in the container to be inspected sealed after being opened to the atmosphere in a second period after the first period;
A pressure change in the inspection target container sealed after pressurizing the inspection target container to a predetermined inspection pressure is measured between the first period and the second period or in a third period after the second period. A third measuring step,
A first temperature compensation value calculating step for obtaining a first temperature compensation value based on the measurement result of the first measuring step;
A second temperature compensation value calculating step for obtaining a second temperature compensation value based on the measurement result of the second measuring step;
A third temperature compensation value calculating step for calculating a third temperature compensation value for temperature compensating the measurement result of the third measurement step based on the first temperature compensation value and the second temperature compensation value;
A determination step of determining the presence or absence of leakage of the inspection target container based on data obtained by performing temperature compensation on the measurement result of the third measurement step with the third temperature compensation value;
Have
In the third temperature compensation value calculation step, at least one of the magnitude of the examination pressure, the magnitude of the heat capacity of the examination target container, the magnitude of the heat transfer rate to the outside, and the magnitude of the temperature difference between the examination target container and the environment The leak inspection method according to claim 1, wherein the weighting of the first temperature compensation value and the second temperature compensation value in calculating the third temperature compensation value is changed based on one. As a pressure change in the inspection target container,
In the first measurement step and the second measurement step, a differential pressure between the reference container opened to the atmosphere or the reference container sealed after being opened to the atmosphere and the inspection object container sealed after being opened to the atmosphere is measured. And
In the third measuring step, a differential pressure between the reference container sealed after being pressurized to the inspection pressure and the inspection object container sealed after being pressurized to the inspection pressure is measured. The leak inspection method according to claim 1. In the third temperature compensation value calculating step, when the third period is between the first period and the second period and the inspection pressure is equal to or higher than a certain value, the heat capacity of the inspection target container is smaller, or The weight of the first temperature compensation value is increased as the heat transfer rate to the outside is larger or the temperature difference between the container to be inspected and the environment is larger. Leak inspection method. In the third temperature compensation value calculating step, when the third period is between the first period and the second period, the weight of the first temperature compensation value is increased as the inspection pressure is higher. The leak inspection method according to any one of claims 1 to 3, wherein The first temperature compensation value, the second temperature compensation value, or the third temperature compensation value is a pressure change amount per unit time when there is no leakage. Leak inspection method described in 1.   A leak inspection apparatus for inspecting whether or not a container to be inspected leaks using the leak inspection method according to claim 1.