Gas leak detection device

Abstract

To reduce the size of a gas leak detector which measures the volume of piping by forcibly exhausting gas in the piping and detects a gas leak from the piping by using the measured volume of the piping.SOLUTION: In the gas leak detector 1, a shut-off valve 2, a discharge control valve 3, and a pressure sensor 4 are arranged in order from the upstream side of a pipe L10, and they are connected to a device body part 6. An orifice 5 is arranged in an exhaust port 33 of the switching valve 3. The device body part 6 measures the piping volume on the basis of a sealing time pressure drop quantity and a discharge time pressure drop quantity measured by switching a piping state to a "gas supply state", a "piping sealing state" and a "piping pressure discharge state" by using the selector valves 2 and 3, and a leakage quantity from the orifice 5 estimated on the basis of the piping pressure. The device body part 6 measures the amount of leakage on the basis of the measured piping volume and the amount of pressure drop at the time of detection measured by switching the piping state to the "gas supply state" and the "piping sealing state" using the switching valves 2 and 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technical field disclosed in this specification relates to a gas leak detection device that detects gas leaks from piping. [Background technology]

[0002] A gas leak detection device detects a gas leak by measuring the pressure change after a certain period of time has elapsed after, for example, pressurizing or depressurizing a pipe to be detected. Gas leaks can be detected based on the pipe volume and the amount of pressure change over a certain period of time. To detect gas leaks with high accuracy, it is desirable to have accurate pipe volume measurements.

[0003] Piping layouts vary from user to user. Therefore, it is difficult to accurately determine the piping volume before assembling the piping. For this reason, some gas leak detection devices supply gas to the piping at the installation destination after the piping is assembled, measure the flow rate and pressure, calculate the piping volume based on the measurement data, and detect gas leaks based on the calculated piping volume.

[0004] For example, the air leak measurement device described in Patent Document 1 pressurizes the pipe to be measured, measures the pressure, and then activates the air blow device to exhaust air from the pipe. The air leak measurement device measures the pressure a predetermined time after exhaust begins. The air leak measurement device estimates the pressure after the predetermined time has elapsed based on the elapsed time since exhaust began and leakage volume pressure drop curve data stored in memory. The air leak measurement device measures the air blow volume using an integrated flow sensor. The air leak measurement device measures the temperature inside the pipe. The air leak measurement device calculates the pipe volume based on the pressure estimated from the time and the measured temperature, pressure, and air blow volume, and calculates the leakage volume based on the calculated pipe pressure and the pressure drop over the predetermined time.

[0005] For example, the gas leakage measuring device described in Patent Document 2 switches between a sealed state in which the pipe is sealed and a discharge state in which gas is discharged from the pipe by opening and closing an exhaust port that opens the pipe to the atmosphere with a valve, or by connecting a tank to the pipe and controlling the connection state between the pipe and the tank with a cock. The leakage measuring device measures the amount of pressure drop over a fixed period of time in the sealed state. The gas leakage measuring device also measures the amount of pressure drop over a fixed period of time in the discharge state. The gas leakage measuring device calculates the pipe volume from these measurement data, and further calculates the leakage amount based on the calculated pipe volume and the amount of pressure drop over a fixed period of time in the sealed state.

[0006] For example, the leak inspection device described in Patent Document 3 supplies a constant amount of inspection gas to a sealed piping line to be inspected and pressurizes it. The leak inspection device detects the flow rate, pressure, and temperature of the inspection gas during pressurization, and calculates the piping volume from the pressurization time until the pressure rise value in the piping line reaches a set value and the amount of inspection gas supplied during that time. Next, the leak inspection device calculates the amount of leakage from the piping line from the amount of pressure drop after a set pressure drop time has elapsed since the piping line was pressurized to a set pressure and the calculated piping volume. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 1-44824 [Patent Document 2] Japanese Patent Application Publication No. 9-288031 [Patent Document 3] Patent No. 4684135 Summary of the Invention [Problem to be solved by the invention]

[0008] The air leak measurement device described in Patent Document 1 and the leak inspection device described in Patent Document 3 require a flow sensor for measuring the amount of air blown and the flow rate, a valve for controlling the flow rate to a set value, etc. As a result, the air leak measurement device described in Patent Document 1 and the leak inspection device described in Patent Document 3 end up being large in size.

[0009] Although the gas leakage measuring device described in Patent Document 2 can detect the pipe volume and leakage amount based on pressure, it requires a valve to open and close the gas outlet, and a tank and cock to vary the pipe volume. Therefore, the gas leakage measuring device described in Patent Document 2 also has a large device size. Therefore, conventional gas leak detection devices have room for improvement in terms of reducing the device size. [Means for solving the problem]

[0010] One aspect of the gas leak detection device disclosed in this specification is (1) a gas leak detection device that is disposed in a pipe that supplies gas and detects gas leaks, the gas leak detection device comprising: an intake valve that controls the supply of the gas; an exhaust valve that is disposed downstream of the intake valve and has an exhaust port and controls the exhaust of the gas from the exhaust port; an orifice that is disposed in the exhaust port and controls the exhaust flow rate to a constant amount; a pressure sensor that is disposed downstream of the exhaust valve and measures pipe pressure, which is the internal pressure of the pipe; and a pressure sensor connected to the pressure sensor, the intake valve, and the exhaust valve. and a controller for controlling the operation of the intake valve and the exhaust valve, wherein the controller controls the piping state of the piping to include a gas supply state in which the gas is supplied to the piping to be measured by causing the intake valve to supply the gas and not causing the exhaust valve to exhaust the gas, a piping sealing state in which the piping to be measured is sealed by causing the intake valve to block the gas and not causing the exhaust valve to exhaust the gas, and a piping pressure state in which the gas in the piping to be measured is exhausted through the orifice by causing the intake valve to block the gas and causing the exhaust valve to exhaust the gas. and a pressure discharge state, and the controller is configured to execute a pipe volume measurement process of setting the piping state to the gas supply state, pressurizing the piping to be measured, and then setting the piping state to the piping pressure discharge state, and measuring, using the pressure sensor, a pressure drop at discharge until a measurement condition is met, and further setting the piping state to the gas supply state, pressurizing the piping to be measured, and then setting the piping state to the piping sealed state, and measuring, using the pressure sensor, a pressure drop at sealing until the measurement condition is met, and calculating a pipe volume of the piping to be measured based on the pressure drop at sealing, the pressure drop at discharge, and a leakage amount from the orifice estimated from the piping pressure; and a leakage amount measurement process of setting the piping state to the gas supply state, pressurizing the piping to be measured, and then setting the piping state to the piping sealed state, and measuring a pressure drop at detection until the measurement condition is met, and calculating the amount of gas leakage in the piping to be measured based on the pipe volume calculated in the pipe volume measurement process and the pressure drop at detection.

[0011] In a gas leak detection device having the above configuration, an orifice disposed in the exhaust port of the exhaust valve controls the amount of gas exhausted from the exhaust port to a constant amount. The amount of leakage from the orifice is proportional to the pipe pressure. Therefore, the gas leak detection device can estimate the amount of leakage from the orifice from the pipe pressure, even if a flow meter or flow control valve is not connected to the exhaust port. The gas leak detection device uses an inlet valve and an exhaust valve to switch the piping state between a "gas supply state," a "pipe pressure discharge state," and a "pipe sealed state," measuring the pressure drop during discharge and the pressure drop during sealing, and calculates the pipe volume based on these measurement data and the amount of leakage from the orifice estimated from the pipe pressure. The gas leak detection device then uses an inlet valve and an exhaust valve to switch the piping state between a "gas supply state" and a "pipe sealed state," measuring the pressure drop during detection, and calculating the amount of leakage from the pipe based on the measurement data and the calculated pipe volume. Therefore, with a gas leak detection device having the above configuration, even if a flow meter or flow control valve is not connected to the exhaust port, the piping volume can be calculated using only the pressure measured by the pressure sensor, and gas leaks can be detected using the calculated piping volume, thereby making it possible to reduce the size of the device.

[0012] (2) In the gas leak detection device described in (1), it is preferable that the measurement condition satisfies either a condition that the pressure drop time, which is the time for measuring the amount of pressure drop, exceeds a time threshold, or a condition that the amount of pressure drop is greater than a pressure threshold.

[0013] A gas leak detection device having the above configuration terminates measurement of the pressure drop amount during the pipe volume measurement process or the leak amount measurement process when the pressure drop amount becomes greater than the pressure threshold, even if the pressure drop time does not exceed the time threshold. Therefore, the gas leak detection device can terminate measurement of the pressure drop amount before the error between the estimated value of the leakage amount from the orifice and the actual leakage amount from the orifice becomes large, which is expected to improve the accuracy of measuring the pipe volume and leakage amount.

[0014] (3) In the gas leak detection device described in (2), it is preferable that the pressure threshold is set to a value equal to or less than 10% of the original pressure of the gas.

[0015] The gas leak detection device having the above configuration is expected to improve the accuracy of measuring the pipe volume and leakage amount by setting the pressure threshold to a value equal to or less than 10% of the original gas pressure. If the pressure threshold is set to a value exceeding 10% of the original gas pressure, the error between the estimated leakage amount from the orifice and the actual leakage amount from the orifice will increase, which may reduce the accuracy of measuring the pipe volume and leakage amount.

[0016] (4) In the gas leak detection device described in (2) or (3), it is preferable to have a measurement condition selection table in which the time threshold is stored in association with the piping volume and a preset leak determination threshold, and the controller sets the time threshold selected from the measurement condition selection table as the time threshold of the measurement condition used in the leak amount measurement process.

[0017] A gas leak detection device having the above configuration can select a time threshold from a measurement condition selection table according to the piping volume and leak judgment threshold, making it possible to calculate the leak amount using the optimal time threshold, which is expected to improve the accuracy of leak amount measurement.

[0018] (5) In the gas leak detection device described in any one of (1) to (4), it is preferable that the gas leak detection device has a memory unit, and the controller executes a first operation detection process to detect a first operation state of one or more directional control valves according to the pipe to be measured in the pipe volume measurement process, and the one or more directional control valves are valves arranged in the pipe and switch the flow of the gas, and the controller stores the calculated pipe volume in the memory unit in association with the first operation state detected in the first operation detection process in the pipe volume measurement process.

[0019] A gas leak detection device having the above configuration stores the pipe volume calculated in association with the pipe being measured in a memory unit, so that the pipe volume of the pipe being measured can be read from the memory unit and used when measuring the leak amount, allowing gas leaks to be detected accurately for each pipe.

[0020] (6) In the gas leak detection device described in (5), it is preferable that the controller executes a second operation detection process to detect a second operation state of the one or more directional control valves according to the piping to be measured in the leakage amount measurement process, the controller stores the calculated leakage amount in the memory unit in association with the second operation state detected in the second operation detection process in the leakage amount measurement process, and the controller further executes an output process to output information related to the leakage based on the leakage amount stored in the memory unit.

[0021] The gas leak detection device having the above configuration stores the calculated leakage amount associated with the pipe being measured in the memory unit 62, and outputs information about the leakage of each pipe based on the stored leakage amount, thereby making it possible to notify of gas leaks for each pipe.

[0022] (7) In the gas leak detection device described in any one of (1) to (6), it is preferable that the piping has an intake pipe for supplying the gas and a plurality of branch pipes branching off from the intake pipe, a directional control valve is provided for controlling the flow of the gas from the intake pipe to the plurality of branch pipes, and the intake valve, the exhaust valve, and the pressure sensor are provided in the intake pipe.

[0023] The gas leak detection device having the above configuration is provided with an air intake valve in addition to the directional control valve, so that the pipe volume and leakage amount can be measured for each pipe with a small number of devices, making it easy to identify the location of the leak.

[0024] (8) In the gas leak detection device described in any one of (1) to (6), it is preferable that the piping has an intake pipe for supplying the gas and a plurality of branch pipes branching from the intake pipe, a directional control valve is provided for controlling the flow of the gas from the intake pipe to the plurality of branch pipes, the intake valve is the directional control valve, the exhaust valve is connected to the branch pipe connected to the directional control valve, and the pressure sensor is provided in the plurality of branch pipes.

[0025] The gas leak detection device having the above configuration has a directional control valve that switches the flow of gas and seals the pipe to be measured, so that the pipe volume and leakage amount can be calculated for each branch pipe, making it easy to identify the location of the leak.

[0026] A control method for realizing the functions of the above-described device, a computer program, and a computer-readable storage medium storing the computer program are also novel and useful. [Effects of the Invention]

[0027] According to the above configuration, a gas leak detection device forcibly evacuates gas inside a pipe, measures the pipe volume, and detects gas leaks in the pipe using the measured pipe volume, and a technology for reducing the size of the device is realized. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a diagram illustrating a schematic configuration of a gas leak detection device according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating the electrical configuration of the device main body. [Figure 3] FIG. [Figure 4] FIG. 10 is a diagram showing an example of orifice leakage information. [Figure 5] FIG. 10 is a diagram showing the relationship between measurement time and pipe pressure. [Figure 6] FIG. 10 is a diagram showing the relationship between measurement time and pipe pressure. [Figure 7]10 is an example of a measurement condition selection table. [Figure 8] 10 is a flowchart showing an example of a control procedure for a pipe volume measurement process and a leakage amount measurement process. [Figure 9] 10 is a flowchart showing an example of a control procedure for a leakage amount measurement process. [Figure 10] 10 is a flowchart illustrating an example of a control procedure for output processing. [Figure 11] 1A and 1B are diagrams illustrating an application example of the gas leak detection device according to the first embodiment. [Figure 12] FIG. 10 is a diagram showing a schematic configuration of a gas leak detection device according to a second embodiment. [Figure 13] 5A and 5B are diagrams illustrating the relationship between a switching valve state and a piping state. [Figure 14] 10A and 10B are diagrams illustrating an application example of the gas leak detection device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, a gas leak detection device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. This embodiment discloses a gas leak detection device for detecting leaks in a supply line for supplying gas or compressed air.

[0030] (First embodiment) <Outline of the pneumatic system> As shown in FIG. 1, the gas leak detection device 1 of the first embodiment is incorporated into a pneumatic system 100 and detects leaks from a pipe L10 that supplies compressed air. In the pneumatic system 100, a directional control valve 130 is disposed in the pipe L10 that supplies compressed air from a gas supply source 110 to a pneumatic actuator 120. Compressed air is an example of a "gas." In FIG. 1, the sealing control valve 2 of the gas leak detection device 1 is in a "shutoff state." The exhaust control valve 3 is in an "exhaust state." The directional control valve 130 disposed in the pipe L10 is in a state in which it supplies compressed air to the first chamber 122.

[0031] In the pneumatic actuator 120, a piston 124 is slidably mounted in a cylinder 121. The cylinder 121 is airtightly divided into a first chamber 122 and a second chamber 123 by the piston 124. A drive rod 125 is connected to the piston 124. The drive rod 125 is inserted into the cylinder 121 so that its tip protrudes outside the cylinder 121. In the pneumatic actuator 120, when the first chamber 122 is pressurized, the drive rod 125 retracts toward the cylinder 121, and when the second chamber 123 is pressurized, the drive rod 125 protrudes from the cylinder 121.

[0032] The directional control valve 130 includes an input port 131, a first output port 132, a first exhaust port 133, a second output port 134, and a second exhaust port 135. The directional control valve 130 switches the flow of compressed air in response to the energization of a first solenoid 136 and a second solenoid 137.

[0033] Specifically, when the first solenoid 136 is energized and the second solenoid 137 is not energized, the input port 131 of the directional control valve 130 communicates with the first output port 132, and the second output port 134 communicates with the second exhaust port 135. This causes the directional control valve 130 to be switched to the "first output position" where compressed air is output from the first output port 132.

[0034] On the other hand, when the first solenoid 136 is not energized and the second solenoid 137 is energized, the input port 131 of the directional control valve 130 communicates with the second output port 134, and the first output port 132 communicates with the first exhaust port 133. This causes the directional control valve 130 to switch to the "second output position" where compressed air is output from the second output port 134.

[0035] The piping L10 has an air supply piping L11, a first branch piping L12, and a second branch piping L13. The air supply piping L11 connects the gas supply source 110 and an input port 131 of the directional control valve 130, and supplies compressed air to the directional control valve 130. The first branch piping L12 connects a first output port 132 of the directional control valve 130 and a first chamber 122 of the pneumatic actuator 120, and supplies compressed air to the first chamber 122. The second branch piping L13 connects a second output port 134 of the directional control valve 130 and a second chamber 123 of the pneumatic actuator 120, and supplies compressed air to the second chamber 123.

[0036] <General configuration of gas leak detection device 1> The gas leak detection device 1 of this embodiment is disposed upstream of the directional control valve 130, i.e., in the air supply pipe L11. The gas leak detection device 1 switches the pipe to be measured in accordance with the operation of the directional control valve 130. The gas leak detection device 1 has a sealing switching valve 2, a discharge switching valve 3, a pressure sensor 4, an orifice 5, and a device main body 6.

[0037] The sealing selector valve 2 controls the supply of gas by opening and closing the air supply pipe L11. The discharge selector valve 3 is disposed downstream of the sealing selector valve 2 and is equipped with an exhaust port 33. The discharge selector valve 3 controls the exhaust from the exhaust port 33. An orifice 5 is disposed in the exhaust port 33. The pressure sensor 4 is disposed downstream of the discharge selector valve 3 and detects the pipe pressure, which is the internal pressure of the pipe L10.

[0038] The device main body 6 is a well-known microcomputer, and is connected to the sealing selector valve 2, the discharge selector valve 3, and the sealing pressure sensor 4. The device main body 6 is connected to a user device 150 that manages the pneumatic system 100, and can send and receive data to the user device 150. The device main body 6 detects the piping pressure based on the pressure sensor signal output by the pressure sensor 4, and controls the operation of the sealing selector valve 2 and the discharge selector valve 3. The device main body 6 will be described later. The sealing selector valve 2 is an example of an "air supply valve." The discharge selector valve 3 is an example of an "exhaust valve." The device main body 6 is an example of a "controller."

[0039] The sealing selector valve 2 and the discharge selector valve 3 of this embodiment are configured in the same manner except for the sealing plug 7 and the orifice 5. Specifically, the sealing selector valve 2 and the discharge selector valve 3 each include input ports 21, 31, output ports 22, 32, and exhaust ports 23, 33. The sealing selector valve 2 and the discharge selector valve 3 can be switched between two positions, an "air supply position" and an "exhaust position," depending on whether solenoids 26, 36 are energized, and switch the flow of compressed air.

[0040] When the solenoids 26, 36 are energized and turned ON, the sealing selector valve 2 and the discharge selector valve 3 are switched to an "air supply position" that connects the input ports 21, 31 and the output ports 22, 32 against the force of the springs 27, 37. On the other hand, when the solenoids 26, 36 are not energized and turned OFF, the sealing selector valve 2 and the discharge selector valve 3 are switched to an "exhaust position" that connects the output ports 22, 32 and the exhaust ports 23, 33 by the biasing force of the springs 27, 37. Note that when the solenoids 26, 36 are de-energized and switched from ON to OFF, the sealing selector valve 2 and the discharge selector valve 3 automatically return to the "exhaust position" by the biasing force of the springs 27, 37.

[0041] The sealing selector valve 2 has an input port 21 connected to the gas supply source 110. The output port 22 is connected to the discharge selector valve 3. The exhaust port 23 is sealed by a sealing plug 7. When the sealing selector valve 2 is in the "air supply position", it opens the pipe L10 and supplies compressed air to the discharge selector valve 3. When the sealing selector valve 2 is in the "exhaust position", it cannot exhaust compressed air from the exhaust port 23. The sealing selector valve 2 closes the pipe L10 and does not supply compressed air to the discharge selector valve 3.

[0042] The discharge switching valve 3 has an input port 31 connected to the output port 22 of the sealing switching valve 2. The output port 32 is connected to the input port 131 of the directional control valve 130. The exhaust port 33 is open to the atmosphere via the orifice 5. When the discharge switching valve 3 is in the "air supply position", it closes the exhaust port 33 and does not discharge air. The discharge switching valve 3 outputs compressed air to the directional control valve 130. When the discharge switching valve 3 is in the "exhaust position", it exhausts compressed air from the exhaust port 23 via the orifice 5 and does not output it to the directional control valve 130. The orifice 5 may also be detachable. When leak measurement is not being performed, the orifice 5 may be removed and the discharge switching valve 3 may be used as a normal residual pressure release valve.

[0043] The orifice 5 controls the exhaust flow rate of the compressed air exhausted from the exhaust port 33 to a constant amount. The amount of leakage from the orifice 5 will be described later.

[0044] It should be noted that the sealing selector valve 2 only needs to have the function of controlling the supply of gas, and may be a valve of a different type or structure from the exhaust selector valve 3, such as a poppet-type two-port valve. However, by having the sealing selector valve 2 and the exhaust selector valve 3 have a similar structure, the gas leak detection device 1 can be expected to use fewer types of valves, thereby reducing costs.

[0045] <Electrical configuration of the device main body> The electrical configuration of the device main body 6 will be described with reference to Fig. 2. In the device main body 6, a CPU 61 is connected to a storage unit 62. The device main body 6 includes a display unit 63, a communication unit 64, a switching valve control unit 65, a switching valve state detection unit 66, a pressure sensor detection unit 67, and a timing unit 68, all of which are connected to the CPU 61.

[0046] The CPU 61 executes various processes in accordance with programs read from the storage unit 62 and based on user operations. The storage unit 62 stores various programs including a detection program 71, and various data including orifice leakage information 72, a measurement condition selection table 73, and pipe volume information 74.

[0047] The detection program 71 is a program for causing the CPU 61 of the gas leak detection device 1 to switch the piping state of the piping L10 using the sealing switching valve 2 and the exhaust switching valve 3, and to measure the piping volume and leakage amount. The process of switching the piping state, measuring the piping volume, and measuring the leakage amount will be described later.

[0048] The orifice leakage information 72 stores the leakage amount from the orifice 5 and the piping pressure in association with each other. The orifice leakage information 72 is stored for each type of orifice 5. The type of orifice 5 is, for example, the orifice diameter and leakage amount. The measurement condition selection table 73 stores the piping volume, leakage amount, and time threshold in association with each other. The time threshold is a threshold that indicates the upper limit of the time for measuring the pressure drop amount (hereinafter referred to as "pressure drop time"). The time threshold is an example of a "measurement condition." The piping volume information 74 stores the piping volume measured by the detection program 71. The orifice leakage information 72, the measurement condition selection table 73, and the piping volume information 74 will be described later.

[0049] The display unit 63 notifies the user of information. The display unit 63 is, for example, an LED lamp or an LCD screen. In addition to the display function, the display unit 63 may be provided with a switch having an operation function. For example, the display unit 63 receives and displays the device status, such as the presence or absence of a leak and the amount of leakage, from the CPU 61. Furthermore, the display unit 63 can also display an abnormal state and notify the user when the amount of leakage in the pipe being measured exceeds a leak determination threshold. The leak determination threshold is a threshold value set in advance by the user to determine the occurrence of a leak in the measurement object.

[0050] The communication unit 64 includes an interface that controls communication with external devices such as the user device 150. For example, the communication unit 64 may receive from the user device 150 various setting values, such as a switching valve control instruction output by the user device 150 to the directional control valve 130, the source pressure of the gas supply source 110, and a leak detection threshold, and pass them to the CPU 61. The communication unit 64 may receive various data, such as the device status, leakage amount, and pressure value, from the CPU 61 and transmit them to the user device 150. The communication method of the communication unit 64 may be wired or wireless. The communication unit 64 may also use a combination of multiple communication methods.

[0051] The switching valve control unit 65 is communicatively connected to the sealing switching valve 2, the discharge switching valve 3, and the directional switching valve 130. The switching valve control unit 65 transmits control signals for controlling the operation of the sealing switching valve 2, the discharge switching valve 3, and the directional switching valve 130 in accordance with the control of the CPU 61 that executes the detection program 71.

[0052] The switching valve state detection unit 66 acquires the control signal output from the switching valve control unit 65 and passes the switching valve state indicating the operating states of the sealing switching valve 2, the discharge switching valve 3, and the directional switching valve 130 to the CPU 61. Note that instead of the control signal, the switching valve state detection unit 66 may inquire about the state of the sealing switching valve 2, the discharge switching valve 3, and the directional switching valve 130 and pass the switching valve state to the CPU 61 based on the response.

[0053] The pressure sensor detection unit 67 acquires the pressure sensor signal output by the pressure sensor 4 and passes the pipe pressure of the pipe L10 to the CPU 61. When the timing unit 68 receives a timing start signal from the CPU 61, it starts measuring time and passes the measured time from the start of measurement to the present time to the CPU 61.

[0054] <Switching piping status> The above-mentioned switching of the piping state will be described with reference to Fig. 3. The piping state of the piping L10 is switched among a "gas supply state," a "piping sealed state," and a "piping pressure discharge state" according to the operation of the sealing switch valve 2 and the discharge switch valve 3.

[0055] The piping state is switched to a "gas supply state" in which compressed air is circulated through the piping L10 by turning on the sealing selector valve 2 and the discharge selector valve 3. The piping state is switched to a "piping sealed state" in which a sealed space is formed in the piping L10 by turning off the sealing selector valve 2 and turning on the discharge selector valve 3. The piping state is switched to a "piping pressure discharge state" in which compressed air is discharged from the piping L10 by turning off the discharge selector valve 3. Note that the piping L10 is shut off by turning off the discharge selector valve 3. Therefore, the detection program 71 may control the sealing selector valve 2 to either ON or OFF.

[0056] <Method for measuring pipe volume and leakage rate> The gas leak detection device 1 of this embodiment pressurizes the pipe to be measured, measures the amount of pressure drop after a certain time has passed, and measures the pipe volume and leakage amount based on the amount of pressure drop.

[0057] For example, Q1 is the leakage rate (L / min) of the pneumatic system 100. Q2 is the leakage rate (L / min) from the orifice 5. V is the piping volume of the piping to be measured. P R is the supply source pressure (MPa). ΔP1 is the pressure drop (MPa) measured in the "piping sealed state". ΔP2 is the pressure drop (MPa) measured in the "piping pressure discharge state". P0 is a constant. In this embodiment, P0 is atmospheric pressure 0.1013 [MPa]. T1 is the pressure drop time (sec) measured in the "piping sealed state". T2 is the pressure drop time (sec) measured in the "piping pressure discharge state".

[0058] In this case, the leakage amount Q1 of the pneumatic system 100, that is, the leakage amount Q1 leaking from the leaking point when the piping to be measured is in a "piping sealed state", can be calculated using Equation 1.

[0059]

number

[0060] On the other hand, when the piping state is set to the "piping pressure discharge state" and forced exhaust is performed from the exhaust port 33, the leakage amount is the sum of the leakage amount Q1 from the pneumatic system 100 (leakage amount from the leaking point) and the leakage amount Q2 from the orifice 5 (exhaust flow rate from the exhaust port 33). The leakage amount Q1+Q2 during forced exhaust can be calculated using Equation 2.

[0061]

number

[0062] By substituting Equation 1 into Equation 2, Equation 3 for calculating the piping volume V can be obtained.

[0063]

number

[0064] By using Equation 3, the gas leak detection device 1 can calculate the pipe volume V based on the leakage amount Q2 from the orifice 5 (exhaust flow rate from the exhaust port 33) and the pipe pressure detected by the pressure sensor 4.

[0065] <About orifice leakage information> Conventionally, when measuring the amount of pressure drop, in addition to measuring the pressure with a pressure sensor, the exhaust flow rate is controlled to a constant rate by a flow sensor or flow control valve. In contrast, the gas leak detection device 1 of this embodiment has an orifice 5 disposed in the exhaust port 33, and controls the exhaust flow rate to a constant rate by the orifice 5 without using a flow meter or flow control valve. The leakage rate Q2 from the orifice 5 varies depending on the piping pressure (primary pressure). Therefore, in the gas leak detection device 1 of this embodiment, orifice leakage information 72 that associates the leakage rate from the orifice 5 with the piping pressure is stored in the memory unit 62.

[0066] An example of the orifice leakage information 72 will be described with reference to FIG. 4. The vertical axis of FIG. 4 indicates the leakage rate (L / min), and the horizontal axis indicates the piping pressure (MPa). The black circles in FIG. 4 represent values ​​obtained by measuring the leakage rate from the first orifice while changing the piping pressure (primary pressure) acting on the first orifice. L1 in the figure is an approximation line of the measured values ​​indicated by the black circles. The white circles in FIG. 4 represent values ​​obtained by measuring the leakage rate from the second orifice while changing the piping pressure (primary pressure) acting on the second orifice. L2 in the figure is an approximation line of the measured values ​​indicated by the white circles.

[0067] As shown by L1 and L2 in the figure, the leakage rate of orifice 5 tends to increase in proportion to the increase in piping pressure, regardless of the orifice diameter. The larger the orifice diameter, the greater the rate at which the leakage rate increases with respect to piping pressure. For example, if a first orifice is set to leak 1.0 L / min when the piping pressure is 0.5 MPa and a second orifice is set to leak 0.5 L / min when the piping pressure is 0.5 MPa, the leakage rate of the first orifice will be twice that of the second orifice, provided that the piping pressure is the same.

[0068] Therefore, even if a flow control valve is not connected to the exhaust port 33 of the exhaust switching valve 3, the gas leak detection device 1 can adjust the exhaust flow rate of compressed air exhausted from the exhaust port 33 by changing the type of orifice 5 (orifice diameter, leakage amount). In addition, the type of orifice 5 selected is one that results in a leakage amount close to the leak determination threshold. The leak determination threshold will be described later.

[0069] 4, the gas leak detection device 1 of this embodiment stores the relationship between the piping pressure and the leakage amount for each type of orifice 5 (orifice diameter in this embodiment) in the orifice leakage information 72. Even if a flow meter is not connected to the exhaust port 33, the gas leak detection device 1 can estimate the leakage amount Q2 from the orifice 5, that is, the exhaust flow rate from the exhaust port 33 or the leakage amount from the measurement object, by comparing the type of orifice 5 disposed in the exhaust port 33 and the piping pressure measured by the pressure sensor 4 with the orifice leakage information 72.

[0070] <Pressure measurement conditions> Conventional gas leak detection devices have no limit on the amount of pressure drop, and only a time threshold is used as a measurement condition for measuring pressure. However, the gas leak detection device 1 of this embodiment uses not only a time threshold but also an upper limit value for the amount of pressure drop (pressure threshold) as a measurement condition. The reason for using two types of measurement conditions is as follows.

[0071] <About pressure threshold> Figure 5 shows the relationship between pressure drop time and pipe pressure when the leakage rate of the measurement target is 1.0 L / min and 0.5 L / min. The vertical axis represents pipe pressure (MPa). The horizontal axis represents pressure drop time (s). In Figure 5, black circles M5 represent the actual measured values ​​of pipe pressure measured repeatedly at a specified sampling interval when the leakage rate is 1.0 L / min. Black diamond marks L5 represent the linear approximation values ​​obtained from the linear approximation formula calculated from the data of pipe pressures between 0.5 MPa and 0.47 MPa among the measured values ​​indicated by black circles M5. Gray circles M6 represent the actual measured values ​​of pipe pressure measured repeatedly at a specified sampling interval when the leakage rate is 0.5 L / min. White diamond marks L6 represent the linear approximation values ​​obtained from the linear approximation formula calculated from the data of pipe pressures between 0.5 MPa and 0.47 MPa among the measured values ​​indicated by gray circles.

[0072] In Figure 5, M5 and M6 are the measured values ​​(pressure sampling data) of the pressure drop when the leakage rate of the measurement target is 1.0 L / min and 0.5 L / min, respectively. Meanwhile, L5 and L6 in the figure are estimated values ​​using a linear approximation formula calculated from the data of the measured values ​​M5 and M6 when the pipe pressure is between 0.5 MPa and 0.47 MPa. The leakage rate of the measurement target decreases as the pipe pressure decreases. Therefore, the time required for pressure drop due to compressed air flowing out of orifice 5 increases as the pipe pressure decreases. Therefore, M5 and M6 in the figure deviate more from L5 and L6 as the pipe pressure decreases. Therefore, if a high pressure threshold is set for the supply pressure, the error between the linear approximation value and the measured value increases, which may reduce the accuracy of pipe volume and leakage rate measurements.

[0073] Therefore, the gas leak detection device 1 of this embodiment sets a pressure threshold value that is as close as possible to the supply pressure and in a range where the error due to pressure drop is small, and terminates pressure measurement if the actual measured value of the pressure drop exceeds the pressure threshold value even before the predetermined time threshold has elapsed.

[0074] If the pressure threshold is small, the time required to measure the pressure drop will be short. As a result, the number of pressures acquired from the pressure sensor 4 will be small, which may result in lower measurement accuracy. Therefore, it is desirable to set the pressure threshold appropriately to a value that allows a predetermined number of data points or more to be acquired from the pressure sensor 4, taking into account the accuracy of the pressure sensor used and fluctuations in the pressure drop time due to the magnitude of the leakage amount of the measurement target.

[0075] In this embodiment, the upper limit of the pressure drop amount (pressure threshold) is set to a value within a range N of less than 10% of the source pressure of the gas supply source 110 (for example, 0.5 MPa to 0.47 MPa), as shown in FIG. 5. If a large pressure drop amount exceeding 10% of the source pressure is set as the pressure threshold, measurement errors due to a decrease in leakage rate accompanying the pressure drop will increase, and there is a possibility that the piping volume and leakage rate will not be measured accurately. However, if the leakage rate to be measured is large or the volume of the object to be measured is small, and there is a concern that the measurement accuracy will decrease due to an extremely short pressure drop time, a pressure drop amount exceeding 10% may be set as the pressure threshold.

[0076] In this embodiment, the pressure threshold is more preferably set to a value in the range of 6% to 8% of the original pressure of the gas supply source 110. If a value less than 6% of the original gas pressure is set as the pressure threshold, there will be little pressure sampling data, and the measurement accuracy of the pipe volume and leakage amount will be low. If a value exceeding 8% of the original gas pressure is set as the pressure threshold, there will be a large error between the estimated value of the leakage amount from the orifice and the actual leakage amount from the orifice, and the measurement accuracy of the pipe volume and leakage amount may be low.

[0077] <About time threshold> As shown in Figure 5, the smaller the leak amount of the object being measured, the smaller the pressure drop rate. The time it takes for the pipe pressure drop to reach the pressure threshold varies depending on the leak amount of the object being measured. For example, if the pressure threshold is 0.03 MPa, the time it takes for the pipe pressure to drop from 0.5 MPa to 0.47 MPa is approximately 25 seconds for the large leak amount L5, and approximately 45 seconds for the small leak amount L6. If the time threshold is set based on the large leak amount L5, then for the small leak amount L6, measurement will end before the pressure drop reaches the pressure threshold. Therefore, the gas leak detection device 1 needs to set a time threshold appropriate for the leak amount of the object being measured.

[0078] Figure 6 shows the relationship between pressure drop time and pipe pressure when the leakage rates of the measurement targets are 1.0 L / min and 0.5 L / min, as in Figure 5, but the pipe volume is larger than that of Figure 5. The vertical axis represents pipe pressure (MPa). The horizontal axis represents pressure drop time (s). The black circles in Figure 6 represent the actual values ​​obtained by repeatedly measuring the pipe pressure at a predetermined sampling interval when the leakage rate is 1.0 L / min. L4 in the figure is a graph of a linear approximation calculated from the data of the pipe pressures between 0.5 MPa and 0.47 MPa among the actual values ​​indicated by the black circles. The gray circles in Figure 5 represent the actual values ​​obtained by repeatedly measuring the pipe pressure at a predetermined sampling interval when the leakage rate is 0.5 L / min. L3 in the figure is a graph of a linear approximation calculated from the data of the pipe pressures between 0.5 MPa and 0.47 MPa among the actual values ​​indicated by the gray circles.

[0079] As shown by L6 and L5 in FIG. 5 and L3 and L4 in FIG. 6, even if the leak rate is the same, the larger the pipe volume, the smaller the pressure drop rate. The time it takes for the pipe pressure drop to reach the pressure threshold varies depending on the pipe volume. For example, when the leak rate is 1.0 L / min, the time it takes for the pipe pressure to drop from 0.5 MPa to 0.47 MPa is approximately 25 seconds when the pipe volume is small, as shown by L5 in FIG. 5, whereas it takes approximately 40 seconds when the pipe volume is large, as shown by L4 in FIG. 6. Also, when the leak rate is 0.5 L / min, the time it takes for the pipe pressure to drop from 0.5 MPa to 0.47 MPa is approximately 45 seconds when the pipe volume is small, as shown by L6 in FIG. 5, whereas it takes approximately 80 seconds when the pipe volume is large, as shown by L4 in FIG. 6. If the time threshold is set based on the piping with a large piping volume in Figure 6, then in piping with a smaller piping volume, the piping pressure will drop to the target value before reaching the time threshold, making the pressure measurement time longer than necessary, as shown in Figure 5. Therefore, the gas leak detection device 1 needs to set an appropriate time threshold for each piping volume.

[0080] Therefore, the gas leak detection device 1 stores a measurement condition selection table 73 shown in Fig. 7 that associates the piping volume, the leakage amount of the measurement object, and the time threshold, and selects the time threshold based on the piping volume and the leakage amount of the measurement object. In this embodiment, the gas leak detection device 1 can select an appropriate time threshold for the measurement object by comparing the piping volume V of the measurement object piping and the leak determination threshold set in advance by the user for determining the leakage state of the measurement object with the measurement condition selection table 73 shown in Fig. 7.

[0081] For example, if the pipe volume is 1 L or less and the leak determination threshold is 0.5 L / min, a time threshold of 60 seconds is selected, and if the pipe volume is 1 L or less and the leak determination threshold is 1.0 L / min, a time threshold of 20 seconds is selected.Also, if the pipe volume is greater than 1 L but less than or equal to 2 L and the leak determination threshold is 0.5 L / min, a time threshold of 120 seconds is selected, and if the pipe volume is greater than 1 L but less than or equal to 2 L and the leak determination threshold is 1.0 L / min, a time threshold of 60 seconds is selected.

[0082] <Pipe volume measurement processing procedure> Next, the procedure of the above-mentioned pipe volume measurement process will be described with reference to FIG. 8(A). When the gas leak detection device 1 receives a pipe volume measurement instruction from the user device 150, for example, the CPU 61 executes the pipe volume measurement process shown in FIG. 8(A) based on the detection program 71 stored in the storage unit 62. The pipe volume measurement instruction may include measurement target identification information that identifies the pipe to be measured and data set or managed by the user, such as the source pressure of the gas supply source 110. The gas leak detection device 1 may also receive the pipe volume measurement instruction from a source other than the user device 150. The gas leak detection device 1 may execute the measurement process from the point in time when it detects that the pipe state has changed to a sealed state and a discharge state based on the switching valve state detected by the switching valve state detection unit 66, or when the user device 150 controls the sealing switching valve 2 and the discharge switching valve 3 to change the pipe state to a sealed state and a discharge state.

[0083] The piping volume remains the same unless the layout is changed. Therefore, the piping volume measurement process only needs to be performed at least once after the gas leak detection device 1 is incorporated into the pneumatic system 100. The piping volume measurement process may be performed, for example, when the gas leak detection device 1 is first started up after being incorporated into the pneumatic system 100. The piping volume measurement process may be performed every time before the leak amount measurement process, which will be described later, is performed. The piping volume measurement process may be performed periodically, such as once a day or once a month, or may be performed during maintenance.

[0084] At the start of the piping volume measurement process, the directional control valve 130 is in the position to which it was switched immediately before. The sealing control valve 2 and the exhaust control valve 3 are turned off and in the exhaust position. The following describes an example in which the piping volume of the first branch piping L12 is measured.

[0085] In the pipe volume measurement process, first, the CPU 61 controls the switching operation of the directional control valve 130 based on the measurement target specifying information attached to the pipe volume measurement instruction (S11).

[0086] For example, suppose the measurement target identification information includes information specifying the first branch pipe L12 shown in Fig. 1 as the measurement target. In this case, the CPU 61 energizes the first solenoid 136 of the directional control valve 130 via the switching valve control unit 65, switching the directional control valve 130 to the first position. As a result, the air supply pipe L11 is connected to the first branch pipe L12, and compressed air is supplied to the first chamber 122 of the pneumatic actuator 120. Compressed air is not supplied to the second chamber 123. The CPU 61 acquires the control signal sent to the directional control valve 130 using the switching valve state detection unit 66, and detects the switching valve state in which the directional control valve 130 is located in the first position.

[0087] 8, the CPU 61 executes a pressure filling process (S12) in which compressed air is supplied to the pipe to be measured, thereby increasing the pipe pressure.

[0088] Specifically, as shown in FIG. 9(A), the CPU 61 sets the piping state to the "gas supply state" (S31). That is, the CPU 61 energizes the solenoid 26 of the sealing switch valve 2 and the solenoid 36 of the discharge switch valve 3 via the switch valve control unit 65, turning on the sealing switch valve 2 and the discharge switch valve 3. The sealing switch valve 2 and the discharge switch valve 3 are placed in the "air supply position." Compressed air supplied from the gas supply source 110 is supplied to the first chamber 122 of the pneumatic actuator 120 via the air supply pipe L11 and the first branch pipe L12. This increases the pipe pressure in the first branch pipe L12.

[0089] The CPU 61 waits for a certain period of time, and when the pipe pressure of the first branch pipe L12 to be measured stabilizes (S32), the process proceeds to S13 in Fig. 8A. The pipe pressure rises to the original pressure of the gas supply source 110 and stabilizes.

[0090] 8A, the CPU 61 executes a piping pressure discharge measurement process. In the piping pressure discharge measurement process, gas is forcibly discharged from the first branch piping L12 to be measured, and a pressure drop amount ΔP2 during discharge and a pressure drop time ΔT2 during discharge are measured.

[0091] Specifically, as shown in FIG. 9(B), the CPU 61 sets the piping state to the "piping pressure discharge state" (S41). That is, the CPU 61 stops the power supply to the discharge switching valve 3 via the switching valve control unit 65, turning off the discharge switching valve 3. The discharge switching valve 3 is switched from the "air supply position" to the "exhaust position," and the compressed air in the first branch piping L12 is discharged from the orifice 5 disposed in the exhaust port 33. The piping pressure in the first branch piping L12 begins to decrease in response to the exhaust from the orifice 5.

[0092] The air supply pipe L11 is blocked by the exhaust switching valve 3. Therefore, the switching state of the sealing switching valve 2 does not affect the exhaust. Therefore, the CPU 61 may or may not output a control signal to the sealing switching valve 2.

[0093] When the CPU 61 switches the piping state to the "piping pressure discharge state" and starts forced exhaust from the exhaust port 33, it acquires a pressure sensor signal from the pressure sensor 4 at a fixed sampling period using the pressure sensor detection unit 67 (S42). That is, the CPU 61 starts measuring the amount of pressure drop and the pressure drop time. Each time the CPU 61 acquires a pressure sensor signal, it determines whether the pressure drop time has exceeded a time threshold (S43). If the CPU 61 determines that the pressure drop time has not exceeded the time threshold (S43: NO), it calculates the difference between the piping pressure at the start of pressure measurement and the current piping pressure as the amount of pressure drop, and determines whether the amount of pressure drop is greater than the pressure threshold (S44).

[0094] The detection program 71 of this embodiment calculates a pressure threshold within a range of 10% or less of the source pressure of the gas supply source 110 attached to the pipe volume measurement instruction. The detection program 71 may store the calculated pressure threshold in the storage unit 62 and read the pressure threshold from the storage unit 62 when executing the subsequent pipe volume measurement process or the leak amount measurement process described below. This avoids repeatedly calculating the pressure threshold when, for example, the source pressure of compressed air rarely changes, thereby reducing the processing load on the gas leak detection device 1. The detection program 71 uses a time threshold that is uniformly set in advance, or a time threshold that the user registers in the device main body 6 via the user device 150.

[0095] If the pressure drop time does not exceed the time threshold (S43: NO) and the pressure drop amount is not greater than the pressure threshold (S44: NO), the CPU 61 returns to the process of S43 and continues measuring the pressure drop time and the pressure drop amount. If the pressure drop time exceeds the time threshold (S43: YES), the CPU 61 ends the pressure measurement without determining whether the pressure drop amount is greater than the pressure threshold, and proceeds to S45. If the pressure drop time does not exceed the time threshold (S43: NO) but the pressure drop amount is greater than the pressure threshold (S44: YES), the CPU 61 ends the pressure measurement and proceeds to S45. S43 and S44 are examples of "measurement conditions."

[0096] In S45, the CPU 61 temporarily stores the pressure drop amount ΔP2 and pressure drop time ΔT2 at the time when the pressure measurement is completed in the storage unit 62. Hereinafter, the pressure drop amount ΔP2 and pressure drop time ΔT2 stored in S45 of the piping volume measurement process are also referred to as the "pressure drop amount ΔP2 at the time of discharge" and the "pressure drop time ΔT2 at the time of discharge." The CPU 61 ends the piping pressure measurement process at the time of discharge and proceeds to S14 in FIG. 8(A).

[0097] 8A, the CPU 61 executes a pressure filling process (S14) and then executes a measurement process when the pipe is sealed (S15). The pressure filling process in S14 is the same as S12, and therefore a description thereof will be omitted. In the measurement process when the pipe is sealed, the pressure drop amount ΔP1 and the pressure drop time ΔT1 are measured with the first branch pipe L12 to be measured sealed.

[0098] Specifically, as shown in FIG. 9(C), the CPU 61 sets the piping state to the "piping sealed state" (S51). That is, the CPU 61 de-energizes the solenoid 26 of the sealing selector valve 2 and energizes the solenoid 36 of the discharge selector valve 3 via the selector valve control unit 65. The sealing selector valve 2 is turned OFF and placed in the "exhaust position." The discharge selector valve 3 is turned ON and placed in the "air supply position." The sealing selector valve 2 closes the air supply pipe L11, thereby sealing the first branch pipe L12. The discharge selector valve 3 closes the exhaust port 33, so the compressed air in the first branch pipe L12 is not exhausted from the exhaust port 33. At this time, if there is a leak in the first branch pipe L12, the compressed air will leak from the leak, and the pipe pressure in the first branch pipe L12 will begin to drop. On the other hand, if there is no leak in the first branch pipe L12, the compressed air will not leak from the first branch pipe L12, and the pipe pressure will be maintained.

[0099] The CPU 61 acquires a pressure sensor signal at a fixed sampling period using the pressure sensor detection unit 67 (S52). The CPU 61 determines whether the pressure drop time exceeds a time threshold (S53) and whether the pressure drop amount is greater than a pressure threshold (S54). Steps S52 to S54 are the same as steps S42 to S44 in FIG. 9B, and therefore will not be described here. The pressure threshold and time threshold used in steps S53 to S54 are the same as those used in steps S43 to S44.

[0100] In S55, the CPU 61 temporarily stores the pressure drop amount ΔP1 and pressure drop time ΔT1 at the time when the pressure measurement is completed in the storage unit 62. Hereinafter, the pressure drop amount ΔP1 and pressure drop time ΔT1 stored in S55 of the piping volume measurement process will also be referred to as the "pressure drop amount ΔP1 at the time of sealing" and the "pressure drop time ΔT1 at the time of sealing." The CPU 61 ends the piping sealed measurement process and proceeds to S16 in FIG. 8(A).

[0101] 8A, the CPU 61 calculates the piping volume V using the above-mentioned formula 3. Specifically, the CPU 61 compares the type of orifice 5 installed in the discharge switching valve 3 and the piping pressure measured by the pressure sensor 4 at the time when pressure measurement is started with the orifice leakage information 72, and estimates the leakage amount Q2 from the orifice 5. For example, if the orifice 5 is the second orifice and the piping pressure measured by the pressure sensor 4 at the time when pressure measurement is started is 0.50 (MPa), the CPU 61 estimates the leakage amount Q2 from the orifice 5 to be 0.5 (L / min) based on L2 in FIG. The CPU 61 reads out the pressure drop amount ΔP2 at the time of discharge, the pressure drop amount ΔP1 at the time of sealing, the pressure drop time ΔT2 at the time of discharge, and the pressure drop time ΔT1 at the time of sealing from the memory unit 62, and applies these data and the estimated value of the leakage amount Q2 to Equation 3 to calculate the piping volume V of the first branch piping L12.

[0102] The CPU 61 acquires the control signal sent from the switching valve control unit 65 to the directional switching valve 130 using the switching valve state detection unit 66, and detects the "first position" operating state of the directional switching valve 130. The CPU 61 associates the calculated pipe volume V of the first branch pipe L12 with the detected "first position" operating state of the directional switching valve 130, and stores this as pipe volume information 74 in the storage unit 62 (S17). The process of detecting the operating state of the directional switching valve 130 in S17 is an example of a "first operation detection process." The detected operating state of the directional switching valve 130 is an example of a "first operating state." Thereafter, the CPU 61 ends the pipe volume measurement process.

[0103] For example, when the CPU 61 receives a pipe volume measurement command accompanied by measurement target identification information specifying the second branch pipe L13, it calculates the pipe volume V of the second branch pipe L13 in the same manner as described above and stores it in the storage unit 62 in association with the operating state "second position" of the directional control valve 130. Thus, the gas leak detection device 1 can measure and store the pipe volume for each pipe to be measured.

[0104] <Leak measurement procedure> Next, the procedure for the leak amount measurement process described above will be explained with reference to Fig. 8(B). When the gas leak detection device 1 receives a leak detection instruction from the user device 150, for example, the CPU 61 executes the leak amount measurement process shown in Fig. 8(B) based on the detection program 71 stored in the storage unit 62. The leak detection instruction may be accompanied by data set or managed by the user, such as measurement target identification information and the source pressure of the gas supply source 110.

[0105] If a leak occurs in the pipe L10, the pneumatic actuator 120 may not operate normally. Therefore, the leakage amount measurement process is repeatedly executed after the pipe volume measurement process is executed. The leakage amount detection process may be executed in response to an instruction from the user device 150 when the pneumatic system is stopped, such as during a lunch break or at night. The leakage amount detection process may be executed at a predetermined timing, such as when the pneumatic system 100 is started or once a week. The leakage amount detection process may be executed in response to a user operation, such as during maintenance.

[0106] At the start of the leakage measurement process, the directional control valve 130 is in the position to which it was previously switched. The sealing control valve 2 and the exhaust control valve 3 are turned off and in the exhaust position. The following describes an example in which the leakage rate of the first branch pipe L12 is measured.

[0107] In the leakage amount measurement process, first, the CPU 61 switches the directional control valve 130 to the "first position" based on the measurement target identification information that specifies the first branch pipe L12 (S70). S70 is similar to S11 in Fig. 8(A), so a description thereof will be omitted. The CPU 61 acquires the control signal sent to the directional control valve 130 by the switching valve control unit 65 using the switching valve state detection unit 66, and detects the operating state of the directional control valve 130.

[0108] The CPU 61 acquires a time threshold and a pipe volume (S71). Specifically, the CPU 61 reads out the pipe volume V associated with the operating state "first position" of the directional control valve 130 detected in S70 from the pipe volume information 74 in the memory unit 62 based on the first branch pipe L12 to be measured. The CPU 61 compares the pipe volume V of the first branch pipe L12 acquired from the memory unit 62 with the leak determination threshold set by the user against the measurement condition selection table 73, and automatically selects the time threshold. Note that if the gas leak detection device 1 has an operation unit that accepts user operations, the time threshold may be manually selected using the operation unit. The CPU 61 may acquire the time threshold by receiving the time threshold selected by the user device 150.

[0109] The CPU 61 executes a pressure filling process to stabilize the pipe pressure in the pipe to be measured (S72). S72 is similar to S12 in Fig. 8(A), and therefore a description thereof will be omitted.

[0110] The CPU 61 executes a measurement process when the pipe is sealed (S73). S73 is executed in the same manner as S15 in FIG. 8A. However, the time threshold value used in S73 is the time threshold value acquired in S71. Therefore, the time threshold value used in the leak amount measurement process is changed depending on the pipe volume of the first branch pipe L12 to be measured and the leak determination threshold value set by the user. Therefore, the leak amount measurement process can appropriately measure pressure changes. Hereinafter, the pressure drop amount ΔP1 and the pressure drop time ΔT1 stored in the memory unit 62 in S73 are also referred to as the "pressure drop amount ΔP1 at detection" and the "pressure drop time ΔT1 at detection."

[0111] The CPU 61 calculates the leakage amount Q1 from the first branch pipe L12 using the above-mentioned formula 1 (S74). Specifically, the CPU 61 calculates the leakage amount Q1 from the first branch pipe L12 by applying the pipe volume V of the first branch pipe L12 acquired from the memory unit 62 in S71, and the pressure drop amount ΔP1 at detection and the pressure drop time ΔT1 at detection stored in the memory unit 62 in S73 to formula 1.

[0112] The CPU 61 acquires the control signal sent from the switching valve control unit 65 to the directional switching valve 130 using the switching valve state detection unit 66, and acquires the state of the directional switching valve 130, which is "first position." The CPU 61 stores the leakage amount Q1 calculated in S74 in association with the acquired operating state of the directional switching valve 130, "first position" (S75), and ends the leakage amount measurement process. The process of detecting the operating state of the directional switching valve 130 in S74 is an example of a "second operation detection process." The detected operating state of the directional switching valve 130 is an example of a "second operating state." The operating state of the directional switching valve 130 detected in S71 may be stored in the storage unit 62, and the leakage amount Q1 calculated in association with the stored operating state may be stored in the storage unit 62.

[0113] For example, when the CPU 61 receives a leakage amount measurement instruction accompanied by measurement target identification information specifying the second branch pipe L13, it calculates the leakage amount Q1 from the second branch pipe L13 in the same manner as described above and stores it in the storage unit 62 in association with the "second position" state of the directional control valve 130. Thus, the gas leak detection device 1 can measure and store the leakage amount Q1 for each pipe to be measured.

[0114] <Output processing> The procedure of the output process for outputting the detection result will be described with reference to Fig. 10. When the CPU 61 receives an output instruction, it reads and acquires the leakage amount Q1 from the storage unit 62 (S101). The output instruction may be received, for example, from the user device 150, or may be received at a timing set in the detection program 71. Alternatively, the output instruction may be received at a timing when the leakage amount measurement process is completed.

[0115] The CPU 61 determines the equipment status based on the leakage amount Q1 read out in S101 (S102). The equipment status may be, for example, the leakage amount Q1 itself. The CPU 61 may compare each leakage amount Q1 with a leakage determination threshold, and determine that "leakage is present" if the leakage amount Q1 exceeds the leakage determination threshold, or determine that "leakage is not present" if the leakage amount Q1 does not exceed the leakage determination threshold, and include the determination result in the equipment status. The leakage amount Q1 is stored, for example, in association with the state of the directional control valve 130. Therefore, the gas leak detection device 1 can determine the presence or absence of a leak and the amount of leakage for each branch pipe, making it easy to identify the location of the leak in the pipe L10.

[0116] The CPU 61 outputs the equipment status determined in S102 to the display unit 63 and displays it (S103). The CPU 61 may transmit the equipment status to the user device 150 via the communication unit 64 and display it. The display method may be, for example, lighting an LED lamp, displaying a list of the presence or absence of a leak and the amount of leakage for each pipe, or identifying the location of the leak on a circuit diagram of the pneumatic system 100 and displaying it together with the amount of leakage. After outputting the equipment status, the CPU 61 ends the output process. Therefore, the user can check the location of the leak and the amount of leakage by looking at the equipment status displayed on the display unit 63 or the user device 150.

[0117] Example 1 11, for example, in a pneumatic system 100, a plurality of pneumatic actuators 120A, 120B...120X are connected to a welding jig, and the welding jig evenly presses down on the workpiece. In this case, the pipe L10 has branch pipes L12A, L12B...L12X and L13A, L13B...L13X, the number of which is twice the number of pneumatic actuators 120, branching from the air supply pipe L11. In the pipe L10, a directional control valve 130A, 130B...130X is provided for each of the pneumatic actuators 120A, 120B...120X.

[0118] When the welding jig is raised to release the workpiece, the directional control valves 130A, 130B... 130X are switched to the first position. When the welding jig is lowered to hold down the workpiece, the directional control valves 130A, 130B... 130X are switched to the second position. For example, if a leak occurs in branch pipe L12B, the force with which pneumatic actuator 120B holds down the welding jig will be weaker than that of the other pneumatic actuators, which could result in poor welding. For this reason, in pneumatic system 100, gas leak detection device 1 is disposed in air supply pipe L11.

[0119] The piping volumes of the branch pipes L12A, L12B...L12X and L13A, L13B...L13X differ depending on the positions of the pneumatic actuators 120A, 120B...120X. For example, the branch pipes L12B, L13B are longer and have a larger piping volume than the branch pipes L12A, L13A.

[0120] However, the gas leak detection device 1 measures the piping volume V with the directional control valves 130A, 130B... 130X placed in the first position, and stores the measured piping volume V associated with the state in which the directional control valves 130A, 130B... 130X are located in the first position in the memory unit 62. Similarly, the gas leak detection device 1 stores the measured piping volume V associated with the state in which the directional control valves 130A, 130B... 130X are located in the second position in the memory unit 62. This allows the memory unit 62 to grasp the piping volumes V separately for the piping that raises the welding jig and the piping that lowers the welding jig.

[0121] When detecting the amount of leakage, the gas leak detection device 1 reads from the storage unit 62 the piping volume V associated with the state in which the directional control valves 130A, 130B... 130X are placed in the first position, measures the pressure drop amount at detection ΔP1 and the pressure drop time at detection ΔT1 with the directional control valves 130A, 130B... 130X placed in the first position, and calculates the amount of leakage Q1. The gas leak detection device 1 stores the calculated amount of leakage Q1 associated with the state in which the directional control valves 130A, 130B... 130X are placed in the first position in the storage unit 62. Similarly, the gas leak detection device 1 may also calculate the amount of leakage Q1 with the directional control valves 130A, 130B... 130X placed in the second position and store the calculated amount of leakage Q1 in the storage unit 62. Therefore, the gas leak detection device 1 can detect the leakage amount Q1 and the presence or absence of leakage separately for the piping that raises the welding jig and the piping that lowers the welding jig, determine the equipment status, and easily identify the location of the leak even in complex circuits.

[0122] <Effects of gas leak detection device> As described above, in the gas leak detection device 1 of the first embodiment, the orifice 5 disposed in the exhaust port 33 of the exhaust switching valve 3 controls the amount of compressed air exhausted from the exhaust port 33 to a constant amount. There is a proportional relationship between the leakage amount from the orifice 5 and the piping pressure. Therefore, the gas leak detection device 1 can estimate the leakage amount from the orifice 5 from the piping pressure even if a flow meter or flow control valve is not connected to the exhaust port 33. The gas leak detection device 1 uses the sealing switching valve 2 and the exhaust switching valve 3 to switch the piping state of the piping L10 between the "gas supply state," "piping pressure exhaust state," and "piping sealed state" to measure the pressure drop amount ΔP2 during discharge and the pressure drop amount ΔP1 during sealing, and calculates the piping volume V based on these measurement data and the leakage amount Q2 from the orifice 5 estimated from the piping pressure. The gas leak detection device 1 then measures the pressure drop ΔP1 during detection by switching the piping state of the piping L10 between the "gas supply state" and the "piping sealed state" using the sealing selector valve 2 and the exhaust selector valve 3, and calculates the leakage amount Q1 from the piping L10 based on the measurement data and the calculated piping volume. Therefore, according to the gas leak detection device 1 of the first embodiment, even if a flow meter or flow control valve is not connected to the exhaust port 33, the piping volume V can be calculated using only the pressure measured by the pressure sensor 4, and a gas leak can be detected using the calculated piping volume V, thereby making it possible to reduce the size of the device.

[0123] The gas leak detection device 1 of the first embodiment terminates measurement of the pressure drop amount during the pipe volume measurement process or the leak amount measurement process when the pressure drop amount becomes greater than the pressure threshold, even if the pressure drop time does not exceed the time threshold. Therefore, the gas leak detection device 1 can terminate measurement of the pressure drop amount before the error between, for example, the estimated value of the leakage amount from the orifice 5 or the measurement object and the actual leakage amount from the orifice 5 or the measurement object becomes large, which is expected to improve the measurement accuracy of the pipe volume V and the leakage amount Q1.

[0124] The gas leak detection device 1 of the first embodiment selects a time threshold from the measurement condition selection table 73 according to the pipe volume V and the leak determination threshold, making it possible to calculate the leak amount Q1 using the optimal time threshold, which is expected to improve the measurement accuracy of the leak amount Q1.

[0125] The gas leak detection device 1 of the first embodiment is provided with a sealing switching valve 2 in addition to the directional control valve 130, so that the pipe volume V and leakage amount Q1 can be measured for each pipe with a small number of devices, making it easy to identify the location of the leak.

[0126] (Second embodiment) Next, a gas leak detection device of a second embodiment will be described. A gas leak detection device 201 of the second embodiment shown in Fig. 12 has a directional control valve 230 that is disposed in the first and second branch pipes L212, L213 and has the function of switching the flow of compressed air and the function of sealing the pipes. This differs from the gas leak detection device 1 of the first embodiment, which is disposed in the air supply pipe L11 and has a sealing control valve 2 that is separate from the directional control valve 130 that switches the flow of compressed air and has the function of sealing the pipes. Here, differences from the first embodiment will be mainly described, and points in common with the first embodiment will be designated by the same reference numerals in the drawings as in the first embodiment, and explanations thereof will be omitted as appropriate.

[0127] <General configuration of gas leak detection device> As shown in FIG. 12, the gas leak detector 201 is disposed in a pipe L210 of a pneumatic system 200 that supplies compressed air from a gas supply source 110 to a pneumatic actuator 120 to operate the pneumatic actuator 120.

[0128] The pneumatic system 200 includes a directional control valve 230 and a pneumatic actuator 120. The directional control valve 230 includes an input port 231, a first output port 232, a first exhaust port 233, a second output port 234, and a second exhaust port 235. The input port 231 is connected to the gas supply source 110 via an air supply pipe L211. The first output port 232 is connected to the first chamber 122 of the pneumatic actuator 120 via a first branch pipe L212. The second output port 234 is connected to the second chamber 123 of the pneumatic actuator 120 via a second branch pipe L213. The first and second exhaust ports 233, 235 are open to the atmosphere.

[0129] The directional control valve 230 switches between a "first position," a "second position," and a "third position" depending on whether a first solenoid 236 and a second solenoid 237 are energized, thereby switching the flow of compressed air. The "first position" is a position in which the input port 231 is connected to the first output port 232 and the second output port 234 is connected to the second exhaust port 235, thereby supplying compressed air to the first branch pipe L212. The "second position" is a position in which the input port 231, the first output port 232, and the second output port 234 are not connected to other ports, thereby sealing both the first and second branch pipes L212 and L213. The "third position" is a position in which the input port 231 is connected to the second output port 234 and the first output port 232 is connected to the first exhaust port 233, thereby supplying compressed air to the second branch pipe L213. When the first and second solenoids 236, 237 are not energized and are turned off, the direction switching valve 230 is biased by the springs 238, 239 and is positioned in the "second position." Note that Fig. 12 illustrates the direction switching valve 230 positioned in the "second position."

[0130] A discharge switching valve 203 is connected to the first branch pipe L212 and the second branch pipe L213. The discharge switching valve 203 has a first input port 2031, a first exhaust port 2032, a second input port 2033, and a second exhaust port 2034. The first input port 2031 is connected to the first branch pipe L212. The second input port 2033 is connected to the second branch pipe L213. The first and second exhaust ports 2032, 2034 are open to the atmosphere. An orifice 5 is provided in each of the first and second exhaust ports 2032, 2034.

[0131] The first and second branch pipes L212 and L213 are provided with pressure sensors 412 and 413, respectively. The pressure sensor 412 is disposed downstream of a connection position D1 where the discharge switching valve 203 connects to the first branch pipe L212. The pressure sensor 412 detects the pipe pressure of the first branch pipe L212. The pressure sensor 413 is disposed downstream of a connection position D2 where the discharge switching valve 203 connects to the second branch pipe L213. The pressure sensor 413 detects the pipe pressure of the second branch pipe L213. The apparatus main body 6 receives pressure sensor signals from the pressure sensors 412 and 413 and can individually acquire the pipe pressure of the first branch pipe L212 and the pipe pressure of the second branch pipe L213.

[0132] The discharge switching valve 203 controls gas discharge by switching between a "non-exhaust position" and an "exhaust position" in response to energization of the solenoid 2036. The "non-exhaust position" is a position in which the first and second input ports 2031, 2033 are not connected to the first and second exhaust ports 2032, 2034, thereby not discharging gas from the first and second branch pipes L212, L213. The "exhaust position" is a position in which the first input port 2031 is connected to the first exhaust port 2032 and the second input port 2033 is connected to the second exhaust port 2034, thereby discharging gas from the first and second branch pipes L212, L213. When the solenoid 2036 is energized and turned ON, the discharge switching valve 203 is positioned in the "exhaust position," and when the solenoid 2036 is not energized and turned OFF, the discharge switching valve 203 is biased by a spring 2037 to be positioned in the "non-exhaust position." FIG. 12 shows the exhaust switching valve 203 in the "non-exhaust position."

[0133] Gas leak detection device 201 includes directional control valve 230, exhaust control valve 203, and pressure sensors 412 and 413, which are connected to device main body 6. Directional control valve 230 is an example of an "air intake valve." Exhaust control valve 203 is an example of an "exhaust valve."

[0134] <Switching piping status> The above-mentioned switching of the piping state will be described with reference to Fig. 13. The detection program 71 controls the gas leak detection device 1 to switch the piping state of the piping L10 between a "first branch piping gas supply state," a "second branch piping gas supply state," a "piping sealed state," and a "piping pressure discharge state" by controlling the switching operation of the sealing switch valve 2 and the discharge switch valve 3.

[0135] The "first branch piping gas supply state" is a piping state in which compressed air is circulated through the first branch piping L212 by energizing the first solenoid 236 to turn on the directional control valve 230 and turn off the exhaust control valve 203. In other words, the detection program 71 can switch the piping state of the piping L210 to the "first branch piping gas supply state" by placing the directional control valve 230 in the "first position" and the exhaust control valve 203 in the "non-exhaust position."

[0136] The "second branch pipe gas supply state" is a piping state in which compressed air is circulated through the second branch pipe L213 by energizing the second solenoid 237 to turn on the directional control valve 230 and turn off the exhaust switch valve 203. In other words, the detection program 71 can switch the piping state of the pipe L210 to the "second branch pipe gas supply state" by placing the directional control valve 230 in the "third position" and placing the exhaust switch valve 203 in the "non-exhaust position."

[0137] The "piping sealed state" is a piping state in which a sealed space is formed in the piping L210 by turning off the directional control valve 230 and the discharge control valve 203. In other words, the detection program 71 can switch the piping state of the piping L210 to the "piping sealed state" by placing the directional control valve 230 in the "second position" and placing the discharge control valve 203 in the "non-exhaust position."

[0138] The "piping pressure discharge state" is a piping state in which the compressed air in the piping L10 is discharged by turning off the directional control valve 230 and turning on the discharge switching valve 203. In other words, the detection program 71 can switch the piping state of the piping L210 to the "piping pressure discharge state" by placing the directional control valve 230 in the "second position" and placing the discharge switching valve 203 in the "exhaust position."

[0139] <Pipe volume measurement processing procedure> The gas leak detection device 201 of the second embodiment calculates the pipe volume according to the procedure shown in Fig. 8(A) A brief explanation will be given of an example in which the first branch pipe L212 is the object of measurement.

[0140] The CPU 61 of the gas leak detection device 201 sets the piping state of the piping L210 to the "first branch piping gas supply state" and supplies compressed air to the first branch piping L212 to stabilize the piping pressure (S11, S12). In this case, the directional control valve 230 is placed in the "first position," and the exhaust switching valve 203 is placed in the "non-exhaust position." Therefore, compressed air is supplied from the air supply piping L11 to the first chamber 122 of the pneumatic actuator 120 via the input port 231, the first output port 232, and the first branch piping L212. This increases the pressure in the first branch piping L212 and the first chamber 122. Accordingly, the compressed air in the second chamber 123 is exhausted via the second branch piping L213, the second output port 234, and the second exhaust port 235 of the directional control valve 230. The pneumatic actuator 120 operates with good responsiveness in response to the pressurization of the first chamber 122. Therefore, the gas leak detection device 1 can smoothly stabilize the pipe pressure of the first branch pipe L212.

[0141] Once the pipe pressure in the first branch pipe L212 has stabilized, the CPU 61 sets the pipe state of the pipe L210 to the "exhaust pressure discharge state," measures the pressure drop amount ΔP2 during discharge and the pressure drop time ΔT2 during discharge, and stores these values ​​in the memory unit 62 (S13). In this case, the directional control valve 230 is placed in the "second position," and the discharge selector valve 203 is placed in the "exhaust position." Therefore, the compressed air filling the first branch pipe L212 is exhausted from the first exhaust port 2032 of the discharge selector valve 203 through the orifice 5. As a result, the internal pressure of the first branch pipe L212 and the first chamber 122 drops. The second chamber 123 is connected to the atmosphere via the second branch pipe L213, the second input port 2033 of the discharge selector valve 203, and the second exhaust port 2034. Therefore, as the pressure in the first chamber 122 drops, outside air flows into the second chamber 123. The pneumatic actuator 120 operates with good responsiveness in response to the exhaust from the first branch pipe L212, and therefore the gas leak detection device 1 can accurately measure the pressure drop ΔP2 during exhaust.

[0142] When either the condition that the pressure drop time exceeds the time threshold or the condition that the pressure drop amount is greater than the pressure threshold is satisfied, the CPU 61 stores the discharge pressure drop amount ΔP2 and the discharge pressure drop time ΔT2 in the memory unit 62.

[0143] Furthermore, the CPU 61 sets the piping state of the piping L210 to the "first branch piping gas supply state" and supplies compressed air to the first branch piping L212 to stabilize the piping pressure (S14).

[0144] Thereafter, the CPU 61 sets the piping state of the piping L210 to the "piping sealed state," measures the sealed pressure drop amount ΔP1 and the sealed pressure drop time ΔT1, and stores them in the memory unit 62 (S15). In this case, the directional control valve 230 is placed in the "second position," and the discharge switching valve 203 is placed in the "non-exhaust position." Therefore, the compressed air filling the first branch piping L212 is not exhausted from the orifice 5. If there is a leak in the first branch piping L212, compressed air is exhausted only from the leak, and the internal pressure of the first branch piping L212 and the first chamber 122 drops. The second chamber 123 is connected to the atmosphere via the second branch piping L213, the second output port 234 of the directional control valve 230, and the second exhaust port 235. Therefore, when the internal pressure of the first branch pipe L212 and the first chamber 122 drops due to leakage from the leak location, outside air flows into the second chamber 123. The pneumatic actuator 120 operates with good responsiveness in response to leakage from the leak location. Therefore, the gas leak detection device 1 can accurately measure the amount of pressure drop ΔP1 when sealed.

[0145] The CPU 61 calculates the piping volume V by applying the leakage amount Q2 from the orifice 5 disposed in the first exhaust port 2032 of the discharge switching valve 203, the measured pressure drop amount ΔP2 at the time of discharge, the pressure drop time ΔT2 at the time of discharge, the pressure drop amount ΔP1 at the time of sealing, and the pressure drop time ΔT1 at the time of sealing to the above-mentioned Equation 3 (S16). The CPU 61 stores the calculated piping volume V in the memory unit 62 as piping volume information 74 in association with the state (first position) of the directional control valve 230 in S11 (S17). As a result, the memory unit 62 stores the piping volume V of the first branch piping L212. Similarly, the gas leak detection device 201 calculates the piping volume V of the second branch piping L213 and stores it in the memory unit 62 as piping volume information 74 in association with the state of the directional control valve 230.

[0146] <Leak measurement procedure> The gas leak detection device 201 of the second embodiment calculates the pipe volume according to the procedure shown in Fig. 8(B) A brief explanation will be given of an example in which the first branch pipe L212 is the object of measurement.

[0147] The CPU 61 of the gas leak detection device 201 sets the piping state of the piping L210 to the "first branch piping gas supply state" and supplies compressed air to the first branch piping L212 to stabilize the piping pressure (S70, S72). Thereafter, the CPU 61 sets the piping state of the piping L210 to the "piping sealed state," measures the amount of pressure drop ΔP1 at the time of detection and the pressure drop time ΔT1, and stores them in the memory unit 62 (S73).

[0148] The CPU 61 reads out the piping volume V corresponding to the state of the directional control valve 230 controlled in S70 from the storage unit 62, and calculates the leakage amount Q1 by applying the read-out piping volume V, the measured pressure drop amount at detection ΔP1, and the pressure drop time at detection ΔT1 to the above-mentioned Equation 1 (S74). The CPU 61 stores the calculated leakage amount Q1 in the storage unit 62 in association with the state of the directional control valve 230 controlled in S70 (S75).

[0149] <Example 2> 14, for example, in a pneumatic system 200, a plurality of pneumatic actuators 120A, 120B...120X are coupled to a welding jig, and the workpiece is evenly held down by the welding jig. In this case, in a piping L210, branch piping L212A, L212B...L212X, L213A, L213B...L213X, the number of which is twice the number of pneumatic actuators 120, branches off from the air supply piping L11. In the piping L210, a directional control valve 230A, 230B...230X and a discharge control valve 203A, 203B...203X are provided for each of the pneumatic actuators 120A, 120B...120X. Further, pressure sensors 412A, 412B...412X, 413A, 413B...413X are respectively provided in the branch pipes L212A, L212B...L212X, L213A, L213B...L213X.

[0150] The device main body 6 is connected to the directional control valves 230A, 230B...230X, the discharge control valves 203A, 203B...203X, and the pressure sensors 412A, 412B...412X, 413A, 413B...413X, and controls the operation of the directional control valves 230A, 230B...230X and the discharge control valves 203A, 203B...203X.

[0151] For example, when branch pipe L12B is the measurement target, gas leak detection device 201 switches the positions of directional control valve 230B and exhaust control valve 203B and detects only the pressure detection signal from pressure sensor 412B to measure pipe volume V and leakage amount Q1. At this time, gas leak detection device 201 sets the other directional control valves 230 to the "second position" and the other exhaust control valves 203 to the "non-exhaust position," and does not supply or exhaust compressed air to branch pipes other than branch pipe L12B.

[0152] Therefore, the gas leak detection device 201 measures the pipe volume V and the leakage amount Q1 by identifying the measurement target from the branch pipes L212A, L212B . . . L212X, L213A, L213B .

[0153] <Effects of gas leak detection device> As described above, in the gas leak detection device 201 of the second embodiment, the orifices 5 disposed in the first exhaust port 2032 and the second exhaust port 2034 of the exhaust switching valve 203 respectively control the amount of compressed air exhausted from the first exhaust port 2032 and the second exhaust port 2034 to a constant amount. There is a proportional relationship between the amount of leakage from the orifice 5 and the piping pressure. Therefore, the gas leak detection device 201 can estimate the amount of leakage from the orifice 5 from the piping pressure even if a flow meter or a flow control valve is not connected to the first exhaust port 2032 or the second exhaust port 2034. The gas leak detection device 201 uses the directional control valve 230 and the discharge switching valve 203 to switch the piping state of the piping L210 between "gas supply state," "piping pressure discharge state," and "piping sealed state" to measure the pressure drop amount ΔP2 at the time of discharge and the pressure drop amount ΔP1 at the time of sealing, and calculates the piping volume V based on the measurement data and the leakage amount Q2 from the orifice 5 estimated from the piping pressure.The gas leak detection device 201 then uses the directional control valve 230 and the discharge switching valve 203 to switch the piping state of the piping L210 between "gas supply state" and "piping sealed state," measure the pressure drop amount ΔP1 at the time of detection, and calculates the leakage amount Q1 from the piping L210 based on the measurement data and the calculated piping volume. Therefore, according to the gas leak detection device 201 of the second embodiment, even if a flow meter or flow control valve is not connected to the first exhaust port 2032 or the second exhaust port 2034, the piping volume V can be calculated using only the pressure measured by the pressure sensors 412, 413, and gas leaks can be detected using the calculated piping volume V, thereby making it possible to reduce the size of the device.

[0154] In the gas leak detection device 201 of the second embodiment, the directional control valve 230 has the function of switching the gas flow and the function of sealing the pipe to be measured, so that the pipe volume V and leakage amount Q1 can be calculated for each of the branch pipes L212A, L212B, L212X...L213A, L213B, L213X, making it easy to identify the location of the leak.

[0155] The present invention is not limited to the above-described embodiments, and various applications are possible without departing from the spirit of the invention. For example, the gas detected by the gas leak detection device 1 may be any gas suitable for the device into which the gas leak detection device 1 is incorporated, and may be a gas other than compressed air. For example, the system into which the gas leak detection device 1 is incorporated may be a system other than the pneumatic system 100. Specifically, the gas leak detection device 1 may be incorporated in a semiconductor manufacturing system that supplies gas to a chamber, and may detect leaks of purge gas. The sealing switching valve 2, the exhaust switching valve, and the directional switching valve 230 may be manual valves, and the flow paths may be switched appropriately in response to manual operation.

[0156] For example, if the user device 150 controls the directional control valve 130, the gas leak detection device 1 may omit the processes of S11 and S70. In this case, the gas leak detection device 1 may detect the state of the directional control valve 130 by acquiring the state from the user device 150.

[0157] For example, the pressure threshold may be a uniformly set value in advance, or may be a value arbitrarily set by the user before executing the piping volume measurement process using the user device 150. However, the gas leak detection device 1, 201 is expected to improve the accuracy of measuring the piping volume and leakage amount by setting the pressure threshold to a value that is 10% or less of the original gas pressure.

[0158] For example, the gas leak detection device 1, 201 does not need to use the time threshold selected from the measurement condition selection table 73 in the leak amount measurement process. However, by selecting a time threshold from the measurement condition selection table 73 according to the piping volume V and a preset leak determination threshold, the gas leak detection device 1, 201 can calculate the leak amount Q1 using the optimal time threshold, which is expected to improve the measurement accuracy of the leak amount Q1.

[0159] For example, the gas leak detection device 1, 201 does not need to store the calculated pipe volume V in the memory unit 62 in association with the state of the directional control valves 130, 230. However, by storing the calculated pipe volume V in association with the pipe to be measured in the memory unit 62, the gas leak detection device 1, 201 can read out and use the pipe volume V to be measured from the memory unit 62 when measuring the leak amount, and can accurately detect gas leaks for each pipe.

[0160] For example, the gas leak detection device 1, 201 does not need to store the calculated leakage amount Q1 in the storage unit 62 in association with the state of the directional control valves 130, 230. However, by storing the calculated leakage amount Q1 in association with the piping to be measured in the storage unit 62 and outputting information about the leakage in each piping based on the stored leakage amount Q1, it becomes possible to notify of a gas leak for each piping.

[0161] For example, the leakage amount shown in Fig. 7 does not have to be set by applying linear approximation to the pressure sampling data, as in the linear approximation values ​​L5 and L6 in Fig. 5 or the graph obtained from the linear approximation formula in Fig. 6. For example, the leakage amount shown in Fig. 7 may be set by applying filter processing other than linear approximation, such as smoothing. By applying filter processing such as linear approximation or smoothing to the pressure sampling data to set the leakage amount shown in Fig. 7, it is possible to suppress variations in the pressure sampling data acting on the external nozzle and improve the measurement accuracy of the pipe volume and leakage amount.

[0162] Furthermore, in any flowchart disclosed in the embodiments, the execution order of multiple processes in any multiple steps can be changed or they can be executed in parallel as long as no contradiction occurs in the processing content.

[0163] The processes disclosed in the embodiments may be executed by hardware such as a single CPU, multiple CPUs, or ASIC, or a combination thereof. The processes disclosed in the embodiments may be realized in various ways, such as a recording medium on which a program for executing the processes is recorded, or a method. [Explanation of symbols]

[0164] 1,201 Gas leak detection devices 2. Sealing switching valve 3. Discharge switching valve 4 Pressure Sensors 5 Orifice 6. Device main body 230 Directional valve 203 Discharge switching valve 412,413 Pressure Sensors

Claims

1. A gas leak detection device that is disposed in a gas supply pipe and detects gas leaks, an air supply valve for controlling the supply of the gas; an exhaust valve disposed downstream of the intake valve, the exhaust valve having an exhaust port, and controlling exhaust of the gas from the exhaust port; an orifice disposed in the exhaust port for controlling the exhaust flow rate to a constant value; a pressure sensor disposed downstream of the exhaust valve for measuring a pipe pressure, which is an internal pressure of the pipe; a controller connected to the pressure sensor, the intake valve, and the exhaust valve, and controlling the operation of the intake valve and the exhaust valve; and The controller determines the piping state of the piping by a gas supply state in which the gas is supplied to the piping to be measured by causing the intake valve to supply the gas and not causing the exhaust valve to exhaust the gas; a piping sealing state in which the piping to be measured is sealed by causing the intake valve to block the gas and not allowing the exhaust valve to exhaust the gas; a piping pressure exhaust state in which the gas in the piping to be measured is exhausted through the orifice by causing the intake valve to shut off the gas and the exhaust valve to exhaust the gas; It is possible to switch to The controller a pipe volume measurement process in which the piping state is set to the gas supply state, the piping to be measured is pressurized, and then the piping state is set to the piping pressure discharge state, and a pressure drop amount during discharge until the measurement condition is met is measured using the pressure sensor; further, the piping state is set to the gas supply state, the piping to be measured is pressurized, and then the piping state is set to the piping sealed state, and a pressure drop amount during sealing until the measurement condition is met is measured using the pressure sensor; and a pipe volume of the piping to be measured is calculated based on the pressure drop amount during sealing, the pressure drop amount during discharge, and the amount of leakage from the orifice estimated from the piping pressure; a leakage amount measurement process for setting the piping state to the gas supply state, pressurizing the piping to be measured, and then setting the piping state to the piping sealed state, measuring a pressure drop at detection until the measurement condition is satisfied, and calculating the amount of gas leakage in the piping to be measured based on the piping volume calculated in the piping volume measurement process and the pressure drop at detection; To execute A gas leak detection device configured as follows.

2. 2. The gas leak detection device according to claim 1, The measurement condition is to satisfy either a condition that a pressure drop time, which is a time for measuring the amount of pressure drop, exceeds a time threshold, or a condition that a pressure drop amount, which is a pressure drop amount, is greater than a pressure threshold. A gas leak detection device configured as follows.

3. 3. The gas leak detection device according to claim 2, The pressure threshold is set to a value equal to or less than 10% of the original pressure of the gas. A gas leak detection device configured as follows.

4. 3. The gas leak detection device according to claim 2, a measurement condition selection table in which the time threshold is stored in association with a piping volume and a preset leak determination threshold, the controller sets the time threshold selected from the measurement condition selection table as the time threshold of the measurement condition used in the leakage amount measurement process. A gas leak detection device configured as follows.

5. 2. The gas leak detection device according to claim 1, A storage unit is included, The controller a first operation detection process is executed to detect a first operation state of one or more directional control valves according to the pipe to be measured in the pipe volume measurement process, the one or more directional control valves being valves disposed in the pipe and switching the flow of the gas; The controller, in the piping volume measurement process, The calculated piping volume is stored in the storage unit in association with the first operation state detected in the first operation detection process. A gas leak detection device configured as follows.

6. 6. The gas leak detection device according to claim 5, The controller execute a second operation detection process to detect a second operation state of the one or more directional control valves according to the piping to be measured in the leakage amount measurement process; The controller, in the leakage amount measurement process, storing the calculated leakage amount in the storage unit in association with the second operation state detected in the second operation detection process; The controller further comprises: executing an output process for outputting information about leakage based on the leakage amount stored in the storage unit; A gas leak detection device configured as follows.

7. 2. The gas leak detection device according to claim 1, the piping includes an air supply piping for supplying the gas and a plurality of branch pipings branching from the air supply piping, and a directional control valve is provided to control the flow of the gas from the air supply piping to the plurality of branch pipings; the intake valve, the exhaust valve, and the pressure sensor are disposed in the intake pipe; A gas leak detection device configured as follows.

8. 2. The gas leak detection device according to claim 1, the piping includes an air supply piping for supplying the gas and a plurality of branch pipings branching from the air supply piping, and a directional control valve is provided to control the flow of the gas from the air supply piping to the plurality of branch pipings; the air intake valve is the directional control valve, the exhaust valve is connected to a branch pipe connected to the directional control valve, The pressure sensors are disposed in the plurality of branch pipes. A gas leak detection device configured as follows.

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