JP4874726B2 - Container leak detection device and detection method - Google Patents

Description

  The present invention relates to a container leak detection apparatus and detection method for detecting the presence or absence of a container leak.

  Conventionally, as this kind of container leak detection apparatus or method, those described in Patent Documents 1 to 3 are known.

  The one described in Patent Document 1 uses a flowmeter equipped with a float position detection sensor for air leak detection, and after the low pressure air is sealed in the container, the float rises if air is flowing, so the sensor is turned off. Thus, the presence of a pinhole in the container is detected.

  In the device described in Patent Document 2, after the container is filled with compressed air, the flow sensor is connected to the container spout, and the output signal of the flow sensor is evaluated.

  In the method described in Patent Document 3, the inspection object is pressurized to atmospheric pressure or higher, a work process for determining the possibility of leakage by the outflow of gas from the inspection object, and the inspection object at atmospheric pressure. And a work process for judging the possibility of leakage by the outflow of gas from the inspection object or the inflow of gas to the detection object, and considering the data obtained in each process mutually The presence / absence of leakage of the inspection object is determined.

  As described above, in each patent document, the presence or absence of a leak is determined accurately and quickly by detecting a leak by measuring a flow rate instead of detecting a leak by a conventional pressure measurement.

JP 2000-46686 A JP-A-7-159274 JP-A-10-185749

  However, as described in each patent document, it takes time to converge the flow rate measurement value when detecting a change in the flow rate after sending air into the container and filling it with air. There is a problem that it is not possible to appropriately cope with a case where the pinhole is very small and / or when it is attempted to further shorten the determination time. According to the experiments by the present inventors, it has been found that the problem that it takes time to converge the flow rate measurement value cannot be solved only by changing the pressure when feeding air into the container, the feeding time, and the like.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a container leak detection device and a detection method capable of detecting minute leaks or shortening the determination time.

In order to achieve the above object, the invention according to claim 1 of the present invention detects a flow rate in a fluid supply source and a flow path between the fluid supply source and the container in order to detect leakage of the container. A leak detection device that determines whether or not there is a leak based on a measured value of the flow sensor after the fluid from the fluid supply source is fed into the container.
A discharge path connected to the container, and a discharge valve for opening and closing the discharge path, the discharge valve being a discharge path during at least a part of a period during which fluid is sent from the fluid supply source to the container To allow the fluid to be discharged from the container.

The invention according to claim 2 is a step of feeding a fluid from a fluid supply source to the container;
A step of detecting a flow rate generated in a flow path between the fluid supply source and the container after a predetermined time elapses after being sent or after the start of feeding;
Determining the presence or absence of leakage from the measured value of the flow rate;
A container leak detection method comprising:
The discharge of the fluid from the container is allowed during at least a part of the step of feeding the fluid.

  According to the present invention, when the fluid is fed from the fluid supply source to the container, the container can be discharged from the container instead of being sealed. As a result, the flow rate flowing through the container can be increased, and the container after stopping the discharge can be completely filled with the fluid. Accordingly, since the measured value of the flow rate is stabilized thereafter in a short time, it is possible to determine whether or not there is a leak in a short time, and even a small leak can be reliably detected.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view of a container leak detection device representing the principle of the present invention. In the figure, the leak detection device 10 includes an air source 12 that is a fluid supply source and a gas flow path 14 that connects the air source 12 and a container C to be inspected. The air source 12 supplies air as a fluid adjusted to a predetermined pressure, and the pressure can be, for example, an absolute pressure between 110 kPa and 200 kPa. When the pressure is high, the entire apparatus must be robust. When the pressure is low, it is difficult to detect leaks. Therefore, a value determined by these trade-offs is preferable.

  The gas flow path 14 is provided with a sending on / off valve 16 that communicates / shields the gas flow path 14. Further, on the downstream side of the on-off valve 16, the gas flow path 14 is branched into a feed gas flow path 14A and a measurement gas flow path 14B. A flow path switching on / off valve 18 for communicating / shielding the inlet gas flow path 14A is provided, and a flow rate sensor 19 is provided for the measurement gas flow path 14B.

  In this example, in order to prevent the flow rate sensor 19 from flowing a large flow rate at the time of air feeding and at the time of flow measurement, the flow is branched into the feeding gas flow channel 14A and the measurement gas flow channel 14B. However, it is also possible to provide a flow sensor without branching. In this case, the flow path switching on-off valve 18 can be omitted.

  A gas flow path 14 is connected to the container C, and a discharge path 20 is connected to the container C. An exhaust valve or a discharge valve 22 for opening / closing the discharge path 20 is provided at the end of the discharge path 20. A pressure sensor 21 is provided in the discharge path 20.

  The downstream end of the gas flow path 14 and the upstream end of the discharge path 20 are formed in a head 23 that is in close contact with the upper portion of the container C.

  The sending on / off valve 16, the flow path switching on / off valve 18, and the discharge valve 22 can each be constituted by an electromagnetic valve, and the opening / closing operation is controlled by a control signal from the control unit 24. FIG. 2 shows a timing chart of the opening / closing operations of the on-off valve 16, the on-off valve 18 for switching the flow path, and the discharge valve 22. When the control unit 24 receives the inspection start trigger signal for the container C, The inlet on / off valve 16, the channel switching on / off valve 18 and the discharge valve 22 are switched for predetermined times t1, t2, and t3 to communicate the channels and open the discharge path 20. The predetermined time t1 corresponds to the time required to inspect one container C, and the predetermined time t2 corresponds to the time required to send air into the container C. The predetermined time t3 corresponds to a part of the predetermined times t1 and t2. Each relationship may be t1> t2> t3.

  A detection signal from the flow sensor 19 is input to the control unit 24, and the determination means 26 determines whether the container C is good or bad, that is, whether there is a leak.

  The operation of the leak detection apparatus 10 configured as described above will be described. When the head 23 is mounted on the container C that can be transported by an arbitrary method and an inspection start trigger signal is generated from a sensor (not shown), the sending on / off valve 16, the flow path switching on / off valve 18 and The discharge valve 22 is simultaneously switched to the open side. As a result, the air from the air source 12 is sent to the container C through the gas passage 14 and mainly the feeding gas passage 14A, and pressurization is performed. At this time, since the discharge path 20 is also open, there is also a flow from the container C to the discharge path 20. As a result, the flow rate is remarkably increased as compared with the case where the discharge path 20 is not opened.

  Next, when the discharge valve 22 is closed after the elapse of the predetermined time t3, the discharge path 20 is closed, so that the pressure in the container C increases and the flow rate decreases rapidly. However, since the flow rate when the discharge passage 20 is open is high, the integrated value of the flow rate is high, and as a result, a large amount of air flows into the container C.

  After the flow rate has dropped rapidly, when a predetermined time t2 has passed and the flow path switching on-off valve 18 is closed, the flow path in which air is mainly fed into the container C through the gas flow path 14A is Since only the measurement gas flow path 14B is switched, the flow rate measured thereafter increases. The increased flow rate measurement value then converges to a substantially constant value. Since the constant value at this time shows a significant difference depending on the presence or absence of leakage of the container C, the determination unit 26 of the control unit 24 takes in a measurement signal from the flow sensor 19, and uses the measured value of the flow rate as a threshold value. Compared to determine if there is a leak if the measured flow rate is greater than or equal to the threshold or greater than the threshold, and if there is no leak if the measured flow rate is less than or less than the threshold, ensure that there is no leak Can be detected.

  After the detection, the sending on / off valve 16 is closed with the elapse of the predetermined time t1, and the inspection for one container C is finished.

  FIG. 3 is a graph showing the flow rate and pressure (measured in the discharge path) when (a) the discharge is performed by the discharge valve and (b) when the discharge valve is not provided. As is clear from the figure, when the discharge valve is not provided, the pressure immediately saturates to a constant value, but the absolute value of the flow rate cannot be increased. As a result, the flow rate flowing into the container C is small, and the container It is impossible to completely fill C so that air can reach every corner. Therefore, the flow rate does not become stable in a short time, and the variation in data increases to determine the presence or absence of leakage.

  On the other hand, when discharging with the discharge valve, the pressure is small because there is discharge from the container C during discharging, but the flow rate increases, so even after stopping the discharge, it flows into the container at a high flow rate. The container C can be filled up. Therefore, since the change in the flow rate after it becomes full is small, the flow rate converges to a constant value and stabilizes immediately after being full, so that it is possible to determine the presence or absence of leakage in a short time. Since the container C can be filled up reliably, even a small leak can be reliably detected as a change in the flow rate value.

It is the schematic of the leak detection apparatus of the container showing the principle of this invention. It is a figure showing the timing chart of each valve. (A) It is a graph which shows each flow volume and pressure (measured in a discharge channel) when discharging by a discharge valve, and (b) when a discharge valve is not provided, and there is a leak in the container with a dotted line for the flow rate Data, and solid lines represent data when there is no leakage in the container.

Explanation of symbols

10 Leakage detection device 12 Air source (fluid supply source)
14 Gas flow path 19 Flow rate sensor 20 Discharge path 22 Discharge valve C Container

Claims (2)

In order to detect leakage of the container, a fluid supply source and a flow rate sensor that detects a flow rate in a flow path between the fluid supply source and the container, and after the fluid from the fluid supply source is fed into the container In the leak detection device for determining the presence or absence of leak from the measurement value of the flow sensor,
A discharge path connected to the container, and a discharge valve for opening and closing the discharge path, the discharge valve being a discharge path during at least a part of a period during which fluid is sent from the fluid supply source to the container A leak detection device characterized in that the fluid is released from the container by opening the valve. Sending fluid from the fluid supply source to the container;
A step of detecting a flow rate generated in a flow path between the fluid supply source and the container after a predetermined time elapses after being sent or after the start of feeding;
Determining the presence or absence of leakage from the measured value of the flow rate;
A container leak detection method comprising:
A container leak detection method which allows discharge of a fluid from a container during at least a part of the step of feeding the fluid.

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