JP2015215216A - Airtightness measuring device and airtightness measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify an airtightness measuring device by eliminating a gas flow meter.SOLUTION: An airtightness measuring device is for an object when a first differential pressure between a first pressure inside the object and an installation environment atmospheric pressure is equal to a set differential pressure. The airtightness measuring device includes: a tank for encapsulating a gas of a second pressure; a flow rate adjustment valve for adjusting a gas flow rate between a tank and the object according to a deviation between the first differential pressure and the set differential pressure; a pressure gauge for outputting a first signal when the pressure inside the tank is a third pressure set value between the first pressure and the second pressure and outputting a second signal when the pressure inside the tank is a fourth pressure set value closer to the first pressure than the third pressure; a timer counter for counting an elapsed time between the time occurrences of the first signal and the second signal; and an estimation part for calculating the airtightness from the elapsed time, the third pressure, the fourth pressure, and a tank volume. The second pressure is a pressure in which the differential pressure between the second pressure and the set environmental atmospheric pressure has the same code as the first differential pressure and the absolute value becomes much larger.

Description

  The present invention relates to an airtightness measuring apparatus and an airtightness measuring method for measuring the internal airtightness of an object.

  Airtightness is required for each of clean rooms, houses, elevators, self-standing closed panels installed to control and monitor processing devices and machines in various facilities.

  Patent Document 1 discloses an apparatus and method for measuring the air density of a clean room and a supply / exhaust duct connected to the clean room. According to Patent Document 1, the clean room is hermetically sealed, the external air feed amount or the internal gas discharge amount is controlled by the blower so that the differential pressure detection means indicates the installation value, and the flow rate of the gas flowing through the blower and the reference value are controlled. The airtightness of the clean room is measured from the deviation.

  Patent Document 2 discloses a closed airtightness measuring device and a measuring method for measuring airtightness when an elevator entrance / exit having a smoke shielding function is closed. The airtightness measuring apparatus of Patent Document 2 includes an atmospheric pressure difference generating means for pressurizing or depressurizing a substantially sealed space, an atmospheric pressure measuring means for measuring the atmospheric pressure in the space, and an atmospheric pressure difference generation between the substantially sealed space. Gas flow rate measuring means for measuring the flow rate of gas flowing between the means. The airtightness is evaluated from the measurement result of the gas flow rate.

  In either case, the airtightness is measured by measuring the pressure difference generating means for generating a pressure difference between the inside and outside of the object, the pressure gauge for detecting the pressure inside or outside the object, and the amount of air leakage. A gas flow meter is used to do this.

Japanese Patent Laid-Open No. 04-157335 JP 2004-224532 A

  Thus, in the conventional airtightness measuring apparatus and method, the measurement of the differential pressure or pressure and the measurement of the gas flow rate are essential. Therefore, there is a problem that it is difficult to simplify the airtightness measuring apparatus. In particular, the gas flowmeter is expensive, and there is a demand for simplifying the airtightness measuring apparatus by making it unnecessary.

  The present invention has been made under the above circumstances, and an object thereof is to simplify an airtightness measuring apparatus by eliminating the need for a gas flow meter.

  In the airtightness measuring apparatus according to the present invention, the first differential pressure obtained by subtracting the atmospheric pressure of the installation environment of the object from the first pressure that is the atmospheric pressure inside the object is a preset differential pressure set in advance. Is a gas tightness measuring device for measuring the gas tightness of the object at the same time, a tank that encloses a gas of a second pressure, a differential pressure gauge that measures the first differential pressure, and the first pressure measuring device. According to the difference between the differential pressure and the set differential pressure, the flow rate adjustment valve for adjusting the flow rate of the gas between the tank and the object, the pressure in the tank is measured, and the measured value is When a third pressure set value between the first pressure and the second pressure is reached, a first signal is output, and the first pressure is set to be greater than the third pressure value. A pressure gauge that outputs a second signal when a fourth pressure set value close to the value is reached; A timer counter that measures an elapsed time between the second signal, the elapsed time, the set value of the third pressure, the set value of the fourth pressure, and the volume of the tank; An evaluation unit that evaluates airtightness, and the second pressure obtained by subtracting the atmospheric pressure of the installation environment from the second pressure is the same as the first differential pressure. The reference sign is a pressure set such that the absolute value thereof is larger than the absolute value of the first differential pressure.

  In the airtightness measuring method according to the present invention, the first differential pressure obtained by subtracting the atmospheric pressure of the installation environment of the target object from the first pressure which is the internal pressure of the target object is a preset differential pressure set. Gas tightness measuring method for measuring the gas tightness of the inside of the object when equal to the gas flow step of flowing the gas between the tank for enclosing the gas of the second pressure and the inside of the object And a differential pressure measuring step for measuring the first differential pressure, and a flow rate of the gas in the gas circulation step is controlled according to a deviation between the measurement result of the first differential pressure and the set differential pressure. The flow rate adjustment step and the pressure in the tank are measured, and when the measured value becomes a third pressure set value between the first pressure and the second pressure, the first signal And a set value of the fourth pressure that is closer to the first pressure than the third pressure A pressure measuring step of outputting a second signal, an elapsed time measuring step of measuring an elapsed time between the first signal and the second signal, the elapsed time, and the third time And a step of evaluating the airtightness of the object from the set value of the pressure, the set value of the fourth pressure, and the volume of the tank, and the second pressure is determined from the second pressure. The second differential pressure obtained by subtracting the atmospheric pressure is the same sign as the first differential pressure, and the absolute value of the second differential pressure is set to be larger than the absolute value of the first differential pressure. It is characterized by that.

  According to the airtightness measuring apparatus and the airtightness measuring method according to the present invention, the gas flow meter is not required, and the airtightness measuring apparatus can be simplified.

It is a block diagram which shows the structural example of the airtightness measuring apparatus which concerns on Embodiment 1 of this application. It is a block diagram which shows the structure of the control part of the airtightness measuring apparatus which concerns on Embodiment 1. FIG. It is a schematic diagram which shows the time change of the tank internal pressure of the airtightness measuring apparatus which concerns on Embodiment 1. FIG. 4 is a flowchart showing the contents of measurement preparation of the airtightness measuring apparatus according to the first embodiment. It is a flowchart which shows the content of the airtightness measurement of the airtightness measuring apparatus which concerns on Embodiment 1. FIG. It is a block diagram which shows the structural example of the airtightness measuring apparatus which concerns on Embodiment 2 of this application. It is a schematic diagram which shows the time change of the tank internal pressure of the airtightness measuring apparatus which concerns on Embodiment 2. FIG. 10 is a flowchart showing the contents of the first measurement preparation of the airtightness measuring apparatus according to the second embodiment. 10 is a flowchart showing the contents of measurement preparations for the second and subsequent times of the airtightness measuring apparatus according to the second embodiment. It is a block diagram which shows the structural example of the airtightness measuring apparatus which concerns on Embodiment 3 of this application.

(Embodiment 1)
With reference to FIG. 1, the airtightness measuring apparatus 50 according to Embodiment 1 of the present application will be described by taking as an example a case where the airtightness measurement target is the self-standing closed type panel 1. Here, the case where the air pressure in the self-standing closed type panel 1 is higher than the environment where the self-standing closed type board 1 is set in advance, that is, the case where air leaks outside from the self-standing closed type board 1 explain.

  The airtightness measuring device 50 includes a tank filled with air of a predetermined pressure in place of the gas flow meter, and air corresponding to the amount of air leaking from the self-closing closed platen 1 from this tank. It is characterized by replenishing. The replenishment of air is executed under conditions controlled so that the pressure difference between the inside and outside of the self-supporting closed type panel 1 becomes a predetermined pressure difference value. In order to achieve this function, the airtightness measuring apparatus 50 according to the first embodiment has the configuration shown in FIG.

  As shown in FIG. 1, the airtightness measuring device 50 measures the pressure difference between the inside and outside of the tank 2, the atmospheric pressure difference generating unit 3 configured by a compressor that injects compressed air into the tank 2, and the self-standing closed platen 1. Differential pressure gauge 4, a flow control valve 5 that controls the flow rate of air injected from the tank 2 into the self-standing closed panel 1, a pressure gauge 6 with two contacts that measures the pressure in the tank 2, and a pressure gauge 6 is provided with a timer counter 7 for starting and stopping time measurement by two contact signals from 6 respectively. In addition, the airtightness measuring device 50 is a compressed air that connects the gas flow path 8 that is an air passage connecting the inside of the self-supporting closed disk 1 and the inside of the tank 2 and the inside of the tank 2 and the pressure difference generating unit 3. The gas flow path 9 is a flow path, and a flow control valve 5 is disposed in the gas flow path 8, and an opening / closing valve 10, a pressure reducing valve 13, and an opening / closing valve 19 for bypassing the pressure reducing valve 13 are provided. In addition, the gas flow path 9 includes an on-off valve 11. Further, a pressure switch 12 provided in the tank 2 is provided. In addition, the airtightness measuring apparatus 50 includes a control unit 14 that controls the operation of the entire airtightness measuring apparatus 50. Note that the bypass on-off valve 19 of the pressure reducing valve 13 is used in a modified example to be described later, and is in a closed state here.

The tank 2 is a tank having a capacity V ₁ that supplies air to the self-standing closed-type board 1 via the gas flow path 8 in order to compensate for air leakage from the self-standing closed-type board 1. At the start of the airtightness measurement, the tank 2 is filled with compressed air having a pressure P ₂ that is sufficiently higher than the pressure P ₁ in the self-standing closed panel 1. At the start of the airtightness measurement, air corresponding to the amount of air leakage from the self-closed mold 1 is supplied from the tank 2 into the self-closed mold 1 via the on-off valve 10, the pressure reducing valve 13 and the flow control valve 5. The Therefore, the pressure in the tank 2 airtightness measurement period is reduced from P _2, to a pressure P _3. Note that the pressure P ₃ is set to a value higher than the pressure P ₁ in the self-supporting closed type panel 1.

  The pressure difference generating unit 3 is a compressor composed of a motor and a compressor, and supplies compressed air to the tank 2 via the gas flow path 9. When compressed air is supplied to the tank 2, as shown by the broken arrow in FIG. 1, in response to a control signal from the control unit 14, the on-off valve 11 is opened, the on-off valve 10 is closed, and the pressure difference generating unit 3 starts. The on-off valve 19 is closed as mentioned above. The atmospheric pressure difference generation unit 3 stops operation in response to a control signal from the pressure switch 12 installed in the tank 2.

Pressure switch 12 provided in the tank 2 is to monitor the pressure in the tank 2, the pressure difference generating unit 3 a control signal pressure is P _2, and outputs to the on-off valve 11. This control signal is an operation stop signal for the pressure difference generator 3 and a valve closing signal for the on-off valve 11. Thus, air in the tank 2 is maintained at a pressure P _2.

The differential pressure gauge 4 is attached to the self-standing closed-type panel ₁ and measures a differential pressure ΔP ₁ inside and outside the self-standing closed-type board 1. Further, as indicated by a broken arrow in FIG. 1, the deviation between the measurement result and a predetermined differential pressure ΔP ₀ is output to the flow control valve 5 as a control signal. Assuming that the atmospheric pressure of the installation environment of the self-standing closed type panel 1 is P ₀ and the atmospheric pressure in the self-standing closed type panel 1 (hereinafter referred to as pressure) is P ₁ , the pressure difference ΔP ₁ inside and outside the self-standing closed type panel ₁ is ΔP ₁ = is a _P 1 -P _0. The deviation control signal is used to maintain the differential pressure ΔP ₁ at a predetermined value ΔP ₀ set in advance. In the case of the self-supporting closed-type panel 1, since the pressure difference between the inside and outside of the self-standing closed-type board 1 at the time of measuring the airtightness is small, a fine differential pressure gauge is usually used as a differential pressure gauge.

The flow rate control valve 5 controls the flow rate of the air flowing through the gas flow path 8 by a deviation control signal output from the differential pressure gauge 4 as indicated by a broken arrow in FIG. As a result, the pressure difference ΔP ₁ inside and outside of the self-supporting closed platen 1 is maintained at ΔP ₀ . Here, since it is assumed that air leaks from the inside of the self-standing closed platen 1 toward the outside, air flows from the tank 2 toward the inside of the self-standing closed platen 1 in the gas flow path 8. At this time, the flow rate control valve 5 restricts the flow rate of the air flowing through the gas flow path 8 if the pressure difference ΔP ₁ is equal to or greater than the specified value ΔP ₀ , and increases the flow rate if it is small. This pressure P ₁ of the self-closing panel 1 by the deviation of the [Delta] P ₁ and [Delta] P ₀ is controlled to be less than ε error that is set in advance.

The pressure switch 12 is activated when the pressure in the tank 2 reaches P ₂ , and outputs a control signal to the atmospheric pressure difference generation unit 3, the on-off valve 11, and the control unit 14 as indicated by a broken arrow in FIG. In response to this control signal, the operation of the atmospheric pressure difference generator 3 is stopped and the on-off valve 11 is closed. The control unit 14 receives the control signal, the air pressure P ₂ is sealed in the tank 2, recognizes that the state of air-tightness measurement can be started.

The pressure gauge 6 is a two-contact pressure gauge and measures the pressure in the tank 2. 2 contacts is higher than the pressure _{P 1} of the self-closing panel 1, and the pressure _{P 2} less pressure _{P 4,} is set to the pressure _{P 3} or more pressure _{P 5} lower than the pressure _{P 4.} When the measured value of the pressure gauge 6 reaches the set pressures P ₄ and P ₅ , the respective contact signals are output to the timer counter 7.

The timer counter 7 measures the elapsed time. Timer counter 7 starts measuring time by contact signal corresponding to the setting pressure P ₄ that is output from the pressure gauge 6, and stops the time measurement by the contact signal corresponding to the setting pressure P _5. Furthermore, the timer counter 7 is provided with a display unit, when the stop time measurement by contact signal corresponding to the setting pressure P _5, and displays on the display section elapsed time Δt is the time measurement result at that time, As shown by an arrow broken line in FIG.

  The control unit 14 receives the start signal of the airtightness measurement, and controls the sealing of the compressed air into the tank 2 which is a preparation work for the airtightness measurement of the self-closing closed platen 1 and the airtightness measurement of the self-closing closed platen 1. Perform execution control.

  As shown in FIG. 2, the control unit 14 includes a CPU (Central Processing Unit) 140, an internal memory 141, an external memory 142, an input device 143, an output device 144, and a bus line 145 that connects each other. The CPU 140 reads the program stored in the external memory 142 via the bus line 145, and implements the following functions by executing the read program using the internal memory 141, the input device 143, and the output device 144. .

  The control unit 14 receives a measurement start signal input via an external input device (not shown) and the input device 143 of the control unit 14, and the arrow in FIG. 1 is input via the input device 143 and the output device 144. Along with control for inputting / outputting control signals indicated by broken lines and inputting measurement results, airtightness is evaluated based on the input measurement results. A site where the airtightness evaluation is performed may be referred to as an evaluation unit. Details of the control contents of the control device will be described below.

The operation principle of the airtightness measuring apparatus 50 according to the first embodiment will be described in detail.
This airtightness measuring device 50, while maintaining the self-closing panel 1 and out of the differential pressure [Delta] P ₁ [Delta] P ₀ predetermined, the air leaking to the outside from the self-closing panel within 1 to tank 2 volume V ₁ refilling with compressed air enclosed pressure P _2.

The differential pressure ΔP ₁ is measured by the differential pressure gauge 4, and a deviation from ΔP ₀ is sent as a control signal to the flow control valve 5, and the pressure reducing valve is supplied from the tank 2 so that the deviation falls within a preset error range. 13, the flow rate of air injected into the self-closing closed platen 1 through the on-off valve 10 and the flow rate control valve 5 is controlled.

By this replenishment, the pressure in the tank 2 decreases with time. The pressure in the tank 2 is P ₂ or less, it becomes set pressure P ₄ that is set in advance, when the further reaches the set pressure P ₅ which is set in advance decreases, the pressure in the tank 2 from P ₄ to P ₅ The time Δt required to decrease is measured. The amount of air replenished from the tank 2 to the self-closing closed platen 1 within this time Δt is proportional to (P ₄ −P ₅ ) · V ₁ . If the proportionality coefficient at this time is k, the replenishment amount of air per unit time, in other words, the leak rate Q of the air leaking outside from the self-standing closed mold plate 1 is expressed by the following equation (1). In the formula (1), (P ₄ −P ₅ ) is described as | P ₄ −P ₅ |. Airtightness means this air leakage rate Q.
Q = k · | P ₄ −P ₅ | · V ₁ / Δt (1)
k: coefficient of unit conversion, P ₄ , P ₅ ; set pressure of pressure gauge 6, V ₁ ; volume of tank 2 Δt; evaluation unit of elapsed time control unit 14 is a value of k stored in external memory 142 in advance , P ₄ and P ₅ , and Δt which is the elapsed time input from the timer counter 7 to the control unit 14, the air leak rate Q is calculated based on the equation (1).

The above explanation regarding the replenishment amount of air is based on the well-known formula PV = nRT. In this equation, P is the pressure of the gas, V is the volume of the gas, n is the number of moles of the gas, R is the Avogadro number, and T is the temperature (temperature) of the gas. When the amount of air is expressed in moles, n = PV / T. At the temperature T, the number of moles Δn of air decreased in the tank 2 when the pressure in the tank 2 having the volume V ₁ is decreased from P ₄ to P ₅ is (P ₄ −P ₅ ) · V ₁ / T. Become. The above equation (1) is the amount of air replenishment when the coefficient for converting the number of moles of air into, for example, the volume of air at 1 atm at a temperature T = 25 ° C., that is, the amount of air leakage. .

Thus, the airtightness measuring device 50 according to the first embodiment, it is necessary to process the measurement preparation encapsulating the compressed air pressure P ₂ in the prior tank 2 airtightness measurement. Airtightness measurement is performed after the compressed air pressure P ₂ enclosed in the tank 2. The content is that an elapsed time Δt during which the pressure in the tank 2 changes from the set pressure P ₄ to P ₅ in the process of replenishing air from the tank 2 to the self-closing closed-type panel 1 is measured. Is to calculate Q.

FIG. 3 shows the change over time of the pressure in the tank 2 when the airtightness test is executed a plurality of times. The horizontal axis is a time axis, and the vertical axis is the pressure of air in the tank 2. In FIG. 3, the pressure change with time is schematically illustrated as a linear change. The time range described as “measurement preparation” on the horizontal axis is the period of preparation for measurement of airtightness. Similarly, the time range indicated as “airtightness measurement” on the horizontal axis is the period of airtightness measurement. In FIG. 3, it is assumed that the inside of the tank 2 is initially the same as the atmospheric pressure (pressure) P _{0 in} the installation environment of the self-standing closed type panel 1. For airtightness measurement. During that period, the pressure of the compressed air in the tank 2 decreases from P ₂ to P ₃ via P ₄ and P ₅ . Therefore, to P ₂ from the pressure P ₀ the pressure by injecting compressed air into the tank 2 in the measurement preparation at locations described first time measured in FIG. In contrast, the measurement preparation of the second and subsequent measurements to P ₂ the pressure in the tank 2 from the pressure P _3.

  Based on the operation principle of the airtightness measuring apparatus 50 described above, first, the contents of the airtightness measurement preparation after the operation of the airtightness measuring apparatus 50 is started will be specifically described in accordance with the flowchart of FIG.

  The control unit 14 closes the opening / closing valve 10 of the gas flow path 8 located at the outlet valve of the tank 2, that is, the outlet of the compressed air from the tank 2, and the inlet valve of the tank 2, that is, the inlet of the compressed air to the tank 2. Control is performed to open the on-off valve 11 of the gas flow path 9 located at (Step S1).

  Next, the control part 14 performs control which starts the driving | operation of the atmospheric | air pressure difference generation part 3 (step S2). Thereafter, compressed air is injected into the tank 2 by the pressure difference generating unit 3, and the pressure in the tank 2 increases with time. The increase in the tank internal pressure during the period described as “Preparation for measurement” in FIG. 3 corresponds to this.

The pressure in the tank 2 the pressure switch 12 operates becomes a P _2. Using this operation signal as a control signal, the pressure difference generator 3 stops operating, and at the same time, the on-off valve 11 that is the inlet valve of the tank 2 is closed (step S3). Further, the operation signal of the pressure switch 12 is sent to the control unit 14 (step S3), and the measurement preparation is completed.

The pressure _{P 2,} the pressure _{P 1} (e.g., 0.2 MPa) sufficiently higher than the self-closing panel 1 is set to, for example, 0.6 MPa.

Next, the airtightness measurement after the measurement preparation is completed will be described according to the flowchart shown in FIG.
The control unit 14 receives the operation signal of the pressure switch 12 and turns on the power supply of the timer counter 7 (step S10).

Then, the control part 14 performs control which opens the on-off valve 10 which is an outlet valve of the tank 2 (step S11). Thereby, the airtightness measurement is substantially started. When the on-off valve 10 is opened, the air can flow from the tank 2 to the self-standing closed mold 1. At this time, the pressure in the tank 2 is continuously measured by the pressure gauge 6 (step S12). The flow rate of air flowing from the tank 2 to the self-supporting closed panel 1 is controlled by the flow control valve 5 so that the deviation between the measurement results ΔP ₁ and ΔP ₀ of the differential pressure gauge 4 is within a predetermined error range. Leakage of air self-closing panel 1 in a state in which such a differential pressure conditions i.e. [Delta] P ₁ is maintained to be within the error range of [Delta] P _0, the amount of air corresponding to the leakage amount of air tanks 2 Is refilled in the self-supporting closed-type disc 1. The pressure of the result tank 2 decreases with time, a pressure P ₃ set as the termination condition of airtightness measured. P ₃ is a value equal to or greater than P ₁ , and the portion indicated as “air tightness measurement” on the horizontal axis in FIG. 3 corresponds to the air tightness measurement period.

Tank pressure in 2, At the set pressure P ₄ that is set in the range of greater than P ₃ with P ₂ below, the pressure gauge 6 outputs a contact signal to the timer counter 7. Receiving this signal, the timer counter 7 starts measuring time with the signal reception time set to 0 (step S13).

Reduced pressure in the tank 2 is further, at the set pressure P ₅ which is set in the small P ₃ or more range than the set pressure P _4, the pressure gauge 6 outputs again contact signal to the timer counter 7. Upon receiving this signal, the timer counter 7 stops time measurement, displays the measurement result on the display unit as the elapsed time, and outputs it to the control unit 14 (step S14).

The control unit 14 inputs the measurement result of the elapsed time output from the timer counter 7 and calculates the leak rate Q according to the equation (1). This value is the evaluation result of the airtightness at the differential pressure ΔP ₀ (step S15).

  As described above, according to the air tightness measuring apparatus 50 according to the first embodiment, air tightness can be measured without using a gas flow meter. Therefore, the apparatus for measuring the airtightness can be simplified as compared with the conventional case. Moreover, since an expensive gas flow meter is not required, the cost of the apparatus can be reduced.

  Note that the air filled in the tank 2 by the pressure difference generating device 3, that is, the compressor may be air obtained from an environment different from the installation environment of the self-standing closed type panel 1. If the installation environment of the self-supporting closed panel 1 is an environment containing corrosive gas, etc., the air containing the corrosive gas or the like is replenished in the self-closing closed panel 1 and stored in the self-closing closed panel 1. There is a risk of damage to the equipment. To avoid this situation, air from a cleaner environment is used for filling. Specifically, for example, a hose or the like is connected to the intake side of the compressor, and air from a clean environment is sucked through the hose or the like.

(First Modification of Embodiment 1)
Although only one tank 2 is shown in FIG. 1, the airtightness measuring apparatus 50 according to the first modification of the first embodiment includes two tanks 2 in parallel. Specifically, the tank 2, the pressure gauge 6, the pressure switch 12, the on-off valve 11, and the on-off valve 10 are provided as one set, and two sets are provided between the pressure difference generating unit 3 and the pressure reducing valve 13. These tanks 2 are connected in parallel. The connection of control signals between the devices constituting each set and the control unit 14 is the same as in the case of FIG. 1 for each set. Further, the contact signals from the pressure gauge 6 provided for each tank 2 are connected to the same timer counter 7 respectively.

This airtightness measuring device 50, the control of the control unit 14, after the two pressure tanks 2 of the procedure shown in FIG. 4 to P _2, using one tank 2, in the procedure shown in FIG. 5 Perform a tightness measurement. In the second measurement, the airtightness measurement is performed using the other tank 2. At this time, one tank 2, while the airtightness measured according to the procedure of measurement preparation shown in FIG. 4, the pressure to P _2. In this way, by switching between the tank 2 used for measurement preparation and the tank 2 used for airtightness measurement every time measurement is completed, no additional time is required for measurement preparation, and gas is used as in the first embodiment. Without a flow meter, it becomes possible to perform hermeticity measurements continuously. The set of tanks 2 need not be limited to two sets.

(Second Modification of Embodiment 1)
Until now, the airtightness measuring device 50 is used when the air pressure (pressure) in the self-standing closed panel 1 is higher than the air pressure (pressure) of the installation environment, that is, when air leaks from the inside of the self-closing closed panel 1 to the outside. Although the configuration and operation are described as being used, the airtightness measuring apparatus 50 according to the second modification of the first embodiment is configured such that the atmospheric pressure (pressure) in the self-supporting closed panel 1 is the atmospheric pressure ( Even if it is lower than (pressure), it can be used for airtightness measurement without a gas flow meter.

The airtightness measuring apparatus 50 according to the second modification has the same configuration as that shown in FIG. However, the pressure difference generating unit 3 shown in FIG. 1 is not a compressor but an exhaust device or a vacuum exhaust device. Further, the on-off valve 19 is opened, and the pressure reducing valve 13 is bypassed in the gas flow path 8. The pressure P ₂ in the tank 2 is set to be lower than the pressure P ₁ of the self-closing panel 1. Therefore, air flows from the self-supporting closed mold 1 toward the tank 2. Therefore, the time change of the pressure in the tank 2 of the air tightness measuring apparatus 50 according to the second modification is symmetrical with respect to the value of the vertical axis P _{0 in} the graph of the pressure change of the tank 2 in FIG. It will be folded back. That is, airtightness measuring pressure in the tank 2 takes place in a range until the P ₃ increases from a low P ₂ than P _0. Note that the pressure P ₃ is set lower than the pressure P ₁ in the self-standing closed mold 1.

In the “measurement preparation” of FIG. 3, the pressure in the tank 2 becomes a pressure P ₂ lower than the initial pressure P ₀ due to the operation of the atmospheric pressure difference generation unit 3 that is an exhaust device. The content of the “measurement preparation” is the same as the content of the flowchart shown in FIG. 4 except that the pressure P ₂ in the tank is lower than the internal pressure P ₁ of the self-standing closed type panel 1.

As described above, when the on-off valve 10 is opened during the airtightness measurement, air flows through the on-off valve 19 from the self-standing closed panel 1 toward the tank 2 through the gas flow path 8. At this time decreases the pressure P ₁ of the self-controlled panel 1, the differential pressure [Delta] P ₁ is a measurement result of the differential pressure gauge 4 is reduced. A deviation from ΔP _{0 of the} differential pressure ΔP ₁ (where the sign is opposite to that in the first embodiment) is output to the flow control valve 5 as a control signal. The flow control valve 5 controls the flow rate of air in the gas flow path 8 based on the deviation so that the deviation does not exceed a predetermined error ε. This point is not different from the case of the first embodiment.

During airtightness measurement, and increases with the initial P ₂ pressure in the tank 2 times, close to the pressure P ₁ of the self-closing panel 1 than P _2, comprising a lower P ₃ than P _1. Set pressure _{P 4} of the pressure gauge 6 is set to a lower range than _{P 1} at _{P 2} or more, the set pressure _{P 5} higher than _{P 4,} is set in the range of _{P 3} or less. Except for the point that the magnitude relationship between the pressure P ₂ and the pressure P _{3 and} the magnitude relationship between the set pressure P ₄ and the set pressure P ₅ are reversed, the contents of the “air tightness measurement” shown in FIG. The contents of the flowchart shown in FIG. The airtightness at this time is the air leakage rate Q from the outside to the inside of the self-closing closed type panel 1, and this Q can be calculated by the equation (1). Since P ₄ <P ₅ , P ₄ -P ₅ is negative. Therefore, in the expression (1), the absolute value is taken as | P ₄ −P ₅ |.

  As described above, according to the airtightness measuring apparatus 50 according to the second modification of the first embodiment in which the pressure difference generating device 3 is an exhaust device, the pressure in the self-closing closed panel 1 is made lower than the pressure in the installation environment. Even in the case, as in the case of the first embodiment, the airtightness can be measured without the gas flow meter.

  Even when the first modification is applied when the pressure in the self-supporting closed panel 1 is made lower than the pressure of the installation environment, the gas tightness is eliminated without the gas flow meter, as in the second modification. Can be measured.

Note that the setting of the pressure P ₂ in the tank 2 described in the first embodiment and the second modification thereof is expressed in the following manner, in either case of the first embodiment or the second modification thereof. In other words, it can be applied regardless of the sign of the pressure difference inside and outside the self-standing closed-type panel 1. That is, the first differential pressure from the pressure P ₁ of the self-closing panel 1, a pressure difference obtained by subtracting the pressure P ₀ of the installation environment, by subtracting the pressure P ₀ from the pressure P ₂ in the tank to give The pressure P ₂ is the same as that of the first differential pressure, and the absolute value of the second differential pressure is the absolute value of the first differential pressure. Is set to be larger than

(Third Modification of Embodiment 1)
The airtightness measuring device 50 according to the third modification includes both a compressor and an exhaust device as the atmospheric pressure difference generation unit 3 and is connected to the tank 2 and between the compressor and the tank 2 and between the exhaust device and the tank 2. Open / close valves provided between the two. The control unit 14 performs control for operating only the opened compressor or exhaust device by opening one of the on-off valves and closing the other. At this time, the controller 14 closes the on-off valve 19 when operating the compressor, and opens the on-off valve 19 when operating the exhaust system. According to the airtightness measuring apparatus 50 configured in this way, airtightness measurement can be performed in both cases where the internal / external differential pressure of the self-standing closed type panel 1 is positive and negative. Furthermore, this third modification can be combined with the first modification, and the same effect as the first modification can be obtained.

(Embodiment 2)
The airtightness measuring device according to the embodiment 2, when air pressure P ₁ of the self-closing panel 1 is higher than the pressure P ₀ of the installation environment, in addition to the tank 2 described in embodiment 1, from tank 2 A supplementary tank filled with compressed air of high pressure is also provided. This airtightness measuring device is characterized in that compressed air is injected from the auxiliary tank into the tank 2 whose pressure has been reduced every time the airtightness measurement is completed, and the pressure is returned to the pressure at the start of the airtightness measurement. To do.

  FIG. 6 shows a configuration example of the airtightness measuring apparatus according to the second embodiment. The airtightness measuring device 60 shown in FIG. 6 differs from the airtightness measuring device 50 shown in FIG. 1 in the following points. The airtightness measuring device 60 includes an auxiliary tank 15, a gas flow path 16 connected to the auxiliary tank 15 and the gas flow path 8, and an on-off valve 17 connected to the gas flow path 16. The gas flow path 16 is connected to the gas flow path 8 between the tank 2 and the on-off valve 10. Furthermore, a back pressure valve 22 installed in the tank 2 and an on-off valve 21 installed between the tank 2 and the back pressure valve 22 are provided. Further, a pressure reducing valve 18 connected to the gas flow path 16 and an on-off valve 20 arranged in parallel with the pressure reducing valve 18 are provided. The on-off valve 20 is used for bypassing the pressure reducing valve 18. In addition to the content of the control in the case of the first embodiment, the control unit 14 further performs opening / closing control of the opening / closing valves 17, 19, 20 and 21.

The auxiliary tank 15 is a tank having a volume V ₂ that encloses air having a pressure P ₆ higher than the pressure P ₂ at the time of starting the airtightness measurement of the tank 2.

Pressure switch 12, unlike the case of Embodiment 1, the set pressure is P _6. When the pressure in the tank 2 (at this time, the pressure in the auxiliary tank 15 is the same) becomes P ₆ , the pressure switch 12 is activated, and the control signal is sent to the atmospheric pressure difference generating unit 3, the on-off valve 11, and the control unit 14. Send to. This pressure difference generating unit 3 by stops operating, the on-off valve 11 is closed, it recognizes that the control unit 14 the pressure in the tank 15 for the auxiliary tank 2 becomes P _6.

Back pressure valve 22, when on-off valve 21 is in the open state, is opened and the pressure in the tank 2 is greater than P _2, the compressed air in the tank 2, to the outside of the tank 2 until the pressure is P ₂ Released. Back pressure valve 22 will close and the pressure in the tank 2 is P ₂ or less. Therefore, the pressure in the tank 2 is maintained at P _2. When the back pressure valve 22 is opened / closed, an opening / closing signal is transmitted to the control unit 14 as a control signal.

  The operating principle of the airtightness measuring device 60 will be described with reference to FIG. FIG. 7 shows the time change of the internal pressure of the auxiliary tank 15 and the time change of the internal pressure of the tank 2 when the airtightness measurement is performed a plurality of times. In FIG. 7, the pressure change with time is schematically illustrated as a linear change. When the air tightness measurement is executed in the air tightness measuring device 60, as in the case of the air tightness measuring device 50 of the first embodiment, as shown in FIG. 7, the measurement preparation period and the actual air tightness measurement are executed. The period to perform is arranged alternately.

As shown in FIG. 6, the auxiliary tank 15 is connected to the atmospheric pressure difference generation unit 3 through the tank 2. Accordingly, the pressure difference generating unit 3 injects compressed air into both the tank 2 and the auxiliary tank 15. The time range described as “first air filling” in FIG. 7 is a period during which compressed air is injected into both the tank 2 and the auxiliary tank 15. At time t ₁ corresponding to the end of this period, the auxiliary tank 15 and tank 2 are filled with air of pressure P ₆ . In this state, the auxiliary tank 15 is disconnected from the gas flow path 8 with the on-off valve 17 closed. Therefore the pressure in the tank 15 for the auxiliary is maintained at P _6.

The period from time t ₂ to t ₃ is a period of “fixed pressure adjustment”. Here, to adjust the pressure in the tank 2 from _{P 6} to _{P 2.} The back pressure valve 22 to the set pressure of the valve opening was P ₂ is available for adjustment.

When the pressure in the tank 2 is P _2, airtightness measuring device 60 (the period of t ₄ from time t ₃ in FIG. 7) to perform similarly airtightness measured as in Embodiment 1 with this tank 2. Therefore, the pressure in the tank 2 is decreased from _{P 2} to _{P 3.}

When performing airtightness measurement for the second time, similarly to the embodiment 1, it is necessary to return the pressure in the tank 2 to P _2. In Embodiment 2, in order to return the pressure in tank 2 to P _2, it utilizes compressed air at a pressure P ₆ which is sealed in the tank 15 for the auxiliary (period t ₆ from the time t ₅ in FIG. 7). Therefore, in a short time as compared with the case of Embodiment 1, it is possible to return the pressure in the tank 2 from P ₃ to P _2. The air in the tank 15 for the auxiliary becomes P ₇ decreases the pressure by replenishing to the tank 2. The pressure in the tank 2 changes in the same manner when the third and subsequent airtightness measurements are performed, and the pressure in the auxiliary tank 15 changes from P ₆ every time the second air filling shown in FIG. It decreases like P ₇ , P ₈ , P ₉ . When the pressure in the tank 15 for the auxiliary approaches the pressure P _2, replenishment of the compressed air from the tank 15 for replenishment to the tank 2 is completed.

  With reference to FIGS. 8 and 9, the operation of the airtightness measuring apparatus 60 will be described more specifically. FIG. 8 shows the contents of the first measurement preparation.

  Here, it is assumed that the atmospheric pressure difference generation unit 3 is a compressor as in the case of the first embodiment. In preparation for first injecting compressed air into the auxiliary tank 15, the control unit 14 closes the on-off valves 10 and 21, and then opens the on-off valves 11, 17, and 20 (step S20). The reason for opening the on-off valve 20 is to bypass the corresponding pressure reducing valve 18. Thus, the compressed air injected from the pressure difference generating unit 3 is efficiently injected not only into the tank 2 but also into the auxiliary tank 15, and the pressure of the air in the tank 2 and the auxiliary tank 15 is reduced. Be the same. The on-off valve 19 is closed here for the same reason as in the first embodiment. In the modification, it is opened.

Next, the control part 14 starts the atmospheric | air pressure difference generator 3 (step S21). Thus, compressed air is injected into the tank 2 and the auxiliary tank 15. The air pressure in the tank 2 and the auxiliary tank 15 is automatically and continuously measured by the pressure gauge 6 and the pressure switch 12 installed in the tank 2. When air pressure in the tank 2 reaches a pressure P _2, the control signal output from the pressure switch 12, along with the operation of the pressure difference generator 3 is stopped by the control signal, the on-off valve 11 is closed (Step S22) . The above corresponds to “first air filling” in FIG. 7.

The control unit 14 recognizes that the pressure in the auxiliary tank 15 has become P ₆ by the control signal output from the pressure switch 12. Then it closes the on-off valve 17 and 20, a tank 15 for the auxiliary, separated from left gas passage 8 maintained its air pressure P ₆ (step S23).

Next, the control unit 14 opens the on-off valve 21 (step S24). This opening is performed at the timing of time t ₂ in FIG. As a result, the back pressure valve 22 functions. Back pressure valve 22 is set to open at a pressure P _2. The pressure in the tank 2, initially, since it is higher P ₆ than P _2, the back pressure valve 22, the pressure in the tank 2 is reduced until the P _2. This corresponds to the portion described as “constant pressure control” in FIG.

Back pressure valve 22 is closed when the pressure in the tank 2 is P _2, and outputs a closing signal. The control unit 14 recognizes that the pressure in the tank 2 is complete, "constant pressure adjustment" becomes P ₂ by the closing signal (step S25). The above is the content of the first measurement preparation.

  Thereafter, the control unit 14 performs the airtightness measurement using the tank 2 as in the flowchart shown in FIG.

  In FIG. 9, the content of the measurement preparation in the case of implementing the airtight measurement after the 2nd time is shown. The portion described as “second air filling” in FIG. 7 corresponds to this measurement preparation.

When the airtightness measurement is completed, the control unit 14 closes the on-off valve 10 and opens the on-off valves 17 and 21 (step S30). Thereby, the compressed air having the pressure P ₆ in the auxiliary tank flows through the pressure reducing valve 18 into the tank 2 having the lower pressure P ₃ . As a result, the pressure in the tank 2 increases (corresponding to “second air filling” in FIG. 7). When the pressure in tank 2 exceeds _{P 2} back pressure valve 22 is opened, the pressure in the tank 2 is maintained at _{P 2} (corresponding to a range of _t 6 ~t ₇ in FIG. 7). The back pressure valve 22 outputs an open signal as a control signal.

The control unit 14 receives the control signal from the back pressure valve 22 and closes the on-off valves 17 and 21 (step S31). Thus, the tank 15 for the auxiliary is disconnected from the gas channel 8, the tank 2 is the situation of functional pressure reducing valve 13 is in a state of the pressure P _2. The closing of the on-off valve 21 in step S31 may be omitted. If omitted, it is not necessary to open the release valve 21 in step S30 in the measurement preparation when performing the third and subsequent dense measurements. The above is the content of the measurement preparation when the second and subsequent airtightness measurements are performed.

  The content of the airtightness measurement is the same as the content shown in the flowchart of FIG.

  As described above, according to the airtightness measuring apparatus 60 according to the second embodiment, airtightness can be measured without using a gas flow meter. Therefore, the apparatus for measuring the airtightness can be simplified as compared with the conventional case. Further, since an expensive gas flow meter is not required, the cost of the apparatus can be reduced. Furthermore, since the auxiliary tank 15 is provided and compressed air can be injected from the auxiliary tank 15 to the tank 2, the time required for sealing the compressed air into the tank 2 at that time can be shortened.

(Modification of Embodiment 2)
In the description so far of the second embodiment, the airtightness measuring device 60 is used when the pressure in the self-standing closed type panel 1 is higher than the pressure in the installation environment, that is, when air leaks from the inside of the self-standing closed type board 1 to the outside. However, the airtightness measuring device 60 according to the modification of the second embodiment is the case where the atmospheric pressure in the self-standing closed panel 1 is lower than the atmospheric pressure in the installation environment. Can also be used for hermeticity measurements.

  In the airtightness measuring apparatus 60 according to the modification, the atmospheric pressure difference generating unit 3 shown in FIG. 6 is not a compressor but an exhaust device or a vacuum exhaust device. Further, the on-off valve 19 is opened, and the pressure reducing valve 13 is in a bypass state. These are the same as those in the second modification of the first embodiment. In this modification, the back pressure valve 22 of the tank 2 is further attached to the tank 2 in the opposite direction.

In the airtightness measuring apparatus 60 according to the modified example, the air flow direction is opposite to that of the airtightness measuring apparatus 60 according to the second embodiment, as in the description of the second modified example of the first embodiment. Therefore, the time change of the pressure in the auxiliary tank 15 and the time change of the pressure in the tank 2 of the airtightness measuring apparatus 60 according to the modified example are shown in the graph of the time change of each pressure shown in FIG. _It is arranged symmetrically with respect to the ₀ horizontal line.

Airtightness measuring device 60 according to the second embodiment, the "constant pressure adjustment" in FIG. 7, the pressure in the tank 2, the P ₂ by discharging the air to the outside from the tank 2 via a back pressure valve 22 Adjust as follows. However, airtightness measuring device 60 according to this modification, at the portion corresponding to the "constant pressure adjustment" in FIG. 7, to adjust the pressure in the tank 2 to P ₂ by causing air to flow from outside the tank 2 . Therefore, the back pressure valve 22 is installed in the opposite direction to that in the second embodiment. Assuming that the pressure range is different and the set value related to the pressure is changed, and that the installation direction of the back pressure valve 22 is changed, the measurement preparation shown in FIGS. The contents of can be directly applied to the airtightness measuring apparatus 60 according to this modification. Further, as described in the second modification of the first embodiment, the contents of the airtightness measurement shown in FIG. 5 can be applied to the airtightness measuring apparatus 60 according to this modification.

  As described above, according to the airtightness measuring device 60 according to the modification of the second embodiment in which the pressure difference generating device 3 is an exhaust device and the installation direction of the back pressure valve 22 is reversed, the pressure in the self-standing closed platen 1 is installed. Even when the pressure is lower than the environmental pressure, the airtightness can be measured without a gas flow meter, as in the case of the second embodiment. Furthermore, since the auxiliary tank 15 is provided and air can pass between the auxiliary tank 15 and the tank 2, the time required to set the pressure inside the tank 2 can be shortened.

It should be noted that the setting of the pressure P ₂ in the tank 2 and the setting of the auxiliary tank P ₆ described in the second embodiment and its modification are expressed as follows, so that either of the second embodiment or its modification is described. This can be applied to both cases. That is, the first differential pressure from the pressure P ₁ of the self-closing panel 1, a pressure difference obtained by subtracting the pressure P ₀ of the installation environment, by subtracting the pressure P ₀ from the pressure P ₂ in the tank to give The pressure P ₂ is the same as that of the first differential pressure, and the absolute value of the second differential pressure is the absolute value of the first differential pressure. Is set to be larger than Further, when the third differential pressure obtained by subtracting the pressure P ₀ from the pressure P ₆ in the tank for the auxiliary pressure P _6, the third differential pressure have the same sign as the second differential pressure The absolute value of the third differential pressure is set to be larger than the absolute value of the second differential pressure.

(Other Modifications of Embodiment 2)
The airtightness measuring apparatus 60 according to the second embodiment and the modification thereof performs “constant pressure adjustment” in FIG.
The back pressure valve 22 is used. However, the airtightness measuring device 60 according to another modification does not use the back pressure valve 22. Therefore, the on-off valve 21 is also unnecessary.

The pressure in the tank 2 changes due to the leakage of the self-standing closed platen 1. The airtightness measuring apparatus 60 according to another modified example waits for the pressure in the tank ₂ to become P2 using this leakage.

  According to the airtightness measuring apparatus 60 according to another modified example, the time required for constant pressure control is increased, but the on-off valve 21 and the back pressure valve 22 are not required, and further, the difference between the self-standing closed mold 1 and the installation environment. Since there is no need to change the installation direction of the back pressure valve 22 depending on the sign of the pressure, it is possible to measure the hermeticity of the self-closing closed platen 1 without using a gas flow meter with a more simplified device configuration. Become.

(Embodiment 3)
As in the second embodiment, the airtightness measuring apparatus according to the third embodiment includes an auxiliary tank in which compressed air having a pressure higher than that of the tank 2 is sealed in addition to the tank 2. The difference from the second embodiment is the arrangement of the tank 2 and the auxiliary tank 15.

  FIG. 10 shows a configuration example of the airtightness measuring apparatus 70 according to the third embodiment. Differences from the second embodiment shown in FIG. 6 are as follows.

  The pressure difference generating unit 3 is directly connected to the auxiliary tank 15 via the on-off valve 11 instead of the tank 2. The pressure switch 12 is not installed in the tank 2 but is installed in the auxiliary tank 15. The other configurations are the same as those shown in FIG.

  In the airtightness measuring apparatus 70 configured in this way, the tank 2 and the auxiliary tank 15 are connected by the gas flow paths 16 and 8, so that the respective pressures are the same as in FIG. 7 of the second embodiment. Can be changed over time. That is, since the compressed air can be injected from the auxiliary tank 15 into the tank 2, the time required for filling the tank 2 with the compressed air can be shortened. The content of the measurement preparation in this case is the same as the flowchart shown in FIGS. 8 and 9 of the second embodiment. Further, the contents of the airtightness measurement are the same as those in the flowchart shown in FIG.

The difference from the second embodiment is that the auxiliary tank 15 is connected to the pressure difference generating unit 3 without going through the tank 2, so that the airtightness measurement is performed using the tank 2. it is that it is possible to return to the original P ₆ the pressure in the tank 15 for the auxiliary driving a pressure difference-generating apparatus 3.

First the airtightness measuring device 60 according to the embodiment 2, in the example shown in FIG. 7, when the pressure of the auxiliary tank 15 is dropped to P _9, the pressure in the tank 15 for replenishment at rest airtightness measurement processing for returning to P ₆ (for example the first filling of the air in FIG. 7) is executed. However, according to the airtightness measuring device 70 according to the third embodiment, in parallel with the airtightness measurement, since the pressure of the auxiliary tank 15 can be returned to the original P _6, a number of times out the airtightness measurement In this case, the total time required for measurement can be further reduced. Incidentally, as in the embodiment 2, for returning the pressure in the tank 2 by utilizing a tank 15 for the auxiliary to the first P _6, it can be shortened time for it. Of course, it is also possible to measure the airtightness of the self-closing closed panel 1 without using a gas flow meter.

  In the description of the first to third embodiments, the target of the airtightness measurement is the self-standing closed platen 1, but the measurement target is not limited to this. As long as there is a need for airtightness measurement, anything such as a clean room, an elevator, or a building may be used.

  In addition, each airtightness measuring device includes a control unit 14, and the control unit 14 controls the opening and closing of various on-off valves. However, the opening / closing valve is not necessarily controlled to be opened / closed by the control unit 14. It may be opened and closed by a person. In that case, the person looks at the instruction of the pressure value measured by the pressure gauge 6 and opens and closes the on-off valve described as being executed by the control unit 14. Thus, even when a person opens and closes the on-off valve, the configuration of the airtightness measuring device according to each embodiment described so far is the same except for the control unit 14, and each airtightness measuring device is the same. The effect of can be produced. Further, the control of the flow control valve 5 based on the measurement result of the differential pressure gauge 4 may be operated by a person. Furthermore, the back pressure valve 22 can be omitted. As described above, the back pressure valve 22 needs to reverse the installation direction when the pressure in the self-standing closed panel 1 is higher and lower than the pressure in the installation environment. However, if it is not necessary to install the back pressure valve 22, such a change in the arrangement is not necessary. Therefore, it is possible to simplify the apparatus and the measurement preparation.

  When the tank 2 and the auxiliary tank 15 are filled with compressed air, the pressure reducing valve is used, but it is not always necessary to use it.

  Until now, although the gas used for an airtightness measurement was air, it is not limited to this. Any gas can be used.

1 Self-supporting closed panel (object)
2 Tank 3 Pressure difference generating part 4 Differential pressure gauge 5 Flow control valve 6 Pressure gauge 7 Timer counter 8, 9 Gas flow path 10, 11, 17, 19, 20, 21 Open / close valve 12 Pressure switch 13, 18 Pressure reducing valve 14 Control part 15 Auxiliary tank 16 Auxiliary flow path 22 Back pressure valve 50, 60, 70 Airtightness measuring device

Claims (6)

Airtightness of the object when the first differential pressure obtained by subtracting the atmospheric pressure of the installation environment of the object from the first pressure, which is the atmospheric pressure inside the object, is equal to a preset differential pressure An airtightness measuring device for measuring
A tank containing a gas of a second pressure;
A differential pressure gauge for measuring the first differential pressure;
A flow rate adjusting valve that adjusts a flow rate of the gas between the tank and the object according to a deviation between the first differential pressure and the set differential pressure;
Measuring the pressure in the tank, and outputting a first signal when the measured value is a third pressure set value between the first pressure and the second pressure; A pressure gauge that outputs a second signal when the fourth pressure set value is closer to the first pressure value than the third pressure value;
A timer counter for measuring an elapsed time between the first signal and the second signal;
An evaluation unit that evaluates airtightness inside the object from the elapsed time, the set value of the third pressure, the set value of the fourth pressure, and the volume of the tank, and
The second pressure is obtained by subtracting the atmospheric pressure of the installation environment from the second pressure, and the second differential pressure has the same sign as the first differential pressure, and its absolute value is the first difference. Pressure set to be greater than the absolute value of pressure,
An airtightness measuring device characterized by that. A first on-off valve for opening and closing the gas flow path;
The gas has a function of either injecting the gas into the tank or exhausting the gas from the tank, and the gas is brought into the tank at the second pressure with the first on-off valve closed. A pressure difference generator configured to form a state enclosed in
The airtightness measuring apparatus according to claim 1, comprising: A first tank and a second tank of known capacity connected to each of the pressure difference generator and the gas flow path;
A pair of first selection on-off valves installed at respective connection sites of the first tank, the pressure difference generation unit, and the gas flow path;
A pair of second selection opening / closing valves installed at respective connection sites of the second tank, the pressure difference generation unit, and the gas flow path,
The tank is one of the first tank and the second tank selected by opening and closing the first selection on-off valve and the second selection on-off valve.
The airtightness measuring apparatus according to claim 2. A first on-off valve for opening and closing the gas flow path;
An auxiliary tank for enclosing the gas at a fifth pressure;
An auxiliary channel that is the gas channel connecting the auxiliary tank and the gas channel; and
A second on-off valve for opening and closing the auxiliary flow path;
With
The first on-off valve is installed between the flow control valve and the tank,
The auxiliary channel is connected to the gas channel between the first on-off valve and the tank,
As for the fifth pressure, a third differential pressure obtained by subtracting the atmospheric pressure of the installation environment from the fifth pressure has the same sign as the second differential pressure, and an absolute value thereof is the second pressure. The pressure is set to be larger than the absolute value of the differential pressure,
The second pressure in the tank is formed by the gas flowing between the tank and the auxiliary tank by opening and closing the first on-off valve and the second on-off valve. Including being,
The airtightness measuring apparatus according to claim 1. The gas has a function of either the gas injection into the auxiliary tank or the gas exhaust from the tank, and the gas is discharged at the fifth pressure with the first on-off valve closed. A pressure difference generator configured to form a state enclosed in the tank;
The airtightness measuring apparatus according to claim 4, comprising: When the first differential pressure obtained by subtracting the atmospheric pressure of the installation environment of the target object from the first pressure that is the internal pressure of the target object is equal to the preset differential pressure, An airtightness measuring method for measuring airtightness,
A gas flow step of flowing the gas between a tank containing a gas of a second pressure and the inside of the object;
A differential pressure measuring step of measuring the first differential pressure;
A flow rate adjusting step for controlling the flow rate of the gas in the gas flow step according to a deviation between the measurement result of the first differential pressure and the set differential pressure;
Measuring the pressure in the tank, and outputting a first signal when the measured value is a third pressure set value between the first pressure and the second pressure; A pressure measuring step of outputting a second signal when the fourth pressure is closer to the first pressure than the third pressure;
An elapsed time measuring step of measuring an elapsed time between the first signal and the second signal;
Evaluating the airtightness of the object from the elapsed time, the set value of the third pressure, the set value of the fourth pressure, and the volume of the tank, and
The second pressure is obtained by subtracting the atmospheric pressure of the installation environment from the second pressure, and the second differential pressure has the same sign as the first differential pressure, and its absolute value is the first difference. Pressure set to be greater than the absolute value of pressure,
An airtightness measuring method characterized by the above.

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