JPH0658834A - Absolute pressure detection sensor and inspecting apparatus for leakage condition of container using same - Google Patents

Abstract

PURPOSE:To obtain an inspecting apparatus for leakage conditions of a container which enables measurement without requiring so much time and moreover at a high accuracy. CONSTITUTION:In the measurement of leakage conditions, a tank is filled with an inert gas at a specified pressure. A CPU 100 performs a detection of a pressure in the tank based on a detection value of a semiconductor sensor 22 and moreover, a compensation according to detection values of the upper or lower temperature sensors 18 or 19 which detect temperatures at the upper or lower parts in the tank. The CPU 100 operates a RAM 102 to store the pressure in the tank after the compensation into a RAM 102 at each fixed time. A measurement data stored is analyzed with the CPU 100 and a judgment is given that there is no leakage when a change in the pressure within a specified time is below a fixed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absolute pressure detecting sensor capable of detecting the absolute pressure of a container to be measured with high accuracy and a leak state detecting device for detecting a leak state of the container using the absolute pressure detecting sensor. In particular, the present invention relates to a leak state inspection device that is optimal for detecting leaks in a tank of a tank truck.

[0002]

2. Description of the Related Art Conventionally, petroleum products such as gasoline, light oil, kerosene, and heavy oil, LPG, liquefied gas such as liquid oxygen, chemicals such as hydrochloric acid, sulfuric acid, alcohol, foods such as molasses, milk, olive oil, and coconut oil. Tank trucks are very often used for animal and vegetable oils such as beef tallow and whale oil and for land transportation such as water supply and sprinkling water.

Since many of these loads are subject to the Fire Defense Law, Poisonous and Deleterious Substances Control Law, High Pressure Gas Control Law, Food Sanitation Law, etc., in order to ensure safety during transportation. The structure and airtightness of the tank are subject to very strict regulations.

Regarding this airtightness, for example, except for the pressure tank, a pressure test of 0.7 kg / cm ² is carried out, and a pressure test of the pressure tank is carried out at a pressure 1.5 times the maximum normal pressure for 10 minutes. No modification is required.

As one of the methods for testing the airtightness, there is a water pressure test method in which water is filled in the tank to inspect for leaks. According to this water pressure test method, first, all the contents stored in the tank are discharged, and then water is filled in the tank, and then 0.2 Kg / cm ^{2 to} 0.7 Kg / cm ² m.
Before the measurement, the inside of the tank is pressurized by the pump up to the pressure of, and left as it is for 60 minutes.

If the difference between the pressure in the tank measured 10 minutes after leaving and the pressure measured after 60 minutes is within 10% or less of the pressurizing pressure, it is judged that there is no airtight state. There is. After that, a process for completely removing the water in the tank is performed.

[0007]

However, in such a conventional water pressure test method, since it is necessary to fill the tank with water for the test, the work takes a very long time. Become. In other words, in the case of a tank truck for exclusive use of gasoline transportation, it is necessary to remove the gasoline before the test, fill it with water after that, and completely remove the water after the measurement, and transport the gasoline immediately after the test. Because I can't get there. This does not apply to tank trucks for water supply, but most tank trucks used for normal transportation are not for water supply, so in general,
It can be said that this test will take about a day.

Further, since a Bourdon tube pressure gauge or the like is usually used for this measurement, it is difficult to measure with high accuracy. Further, since it is a reading type meter that normally uses a dial, it can be read. Since there is always an error, it cannot be said that there is no problem in terms of the reliability of the measurement data.

As described above, since it is practically impossible to detect a leak state using a very small hole, a highly accurate measuring device capable of detecting the state even when the leak is very small is desired. Is the current situation.

The present invention has been made in response to such conventional problems and requirements, and a first object of the present invention is to provide an absolute pressure detecting sensor capable of detecting absolute pressure with high accuracy. The second purpose thereof is to provide a container leakage state inspection device to which the absolute pressure detection sensor is applied, which enables high-accuracy measurement in a short time for measurement. And

[0011]

The absolute pressure detection sensor of the present invention for achieving the above first object is such that a constant pressure is maintained by shutting it from the outside in a casing of which one side is open. The partition wall is arranged so as to form one chamber and a second chamber communicating with the outside and having the same pressure as the outside pressure, and the partition wall has a pressure of the first chamber and a pressure of the second chamber. Is configured to be deformable in accordance with the pressure difference, and the partition wall is provided with a pressure detection unit that outputs an electric signal corresponding to the deformation amount.

Further, the pressure detecting means includes a semiconductor strain sensor whose resistance value changes in accordance with the deformation amount of the partition wall, and a resistor which always exhibits a constant resistance value regardless of the deformation amount. It is characterized in that they are alternately electrically bridge-connected.

Further, the container leakage state inspection device of the present invention for achieving the above second object includes a sealing means for completely sealing the container to be inspected in a state where the contents are contained, and Gas filling means for pressurizing and filling an inert gas to a predetermined pressure in the container sealed by the sealing means, and absolute pressure for detecting the gas pressure in the container to be inspected, which is pressurized and filled by the gas filling means. It is characterized by having a detection sensor and a storage means for storing the gas pressure detected by the absolute pressure detection sensor for each predetermined time.

Further, a sealing means for completely sealing the container to be inspected while the contents are contained therein, and the container sealed by the sealing means is pressurized and filled with an inert gas to a predetermined pressure. A gas filling means, an absolute pressure detection sensor for detecting the gas pressure in the container under pressure filled by the gas filling means, and a gas pressure for each predetermined time detected by the absolute pressure detection sensor are stored. It is characterized by having a storage means and a determination means for determining the leak state of the inspected container based on the change over time of the gas pressure stored in the storage means.

Further, a sealing means for completely sealing the container to be inspected while the contents are contained therein, and the container sealed by the sealing means is pressurized and filled with an inert gas to a predetermined pressure. Gas filling means, an absolute pressure detection sensor for detecting the gas pressure in the container under pressure filled by the gas filling means, a temperature detecting means for detecting the temperature in the container for inspection, and the absolute pressure It has a temperature compensating means for compensating the gas pressure detected by the detection sensor based on the temperature detected by the temperature detecting means, and a storage means for storing the gas pressure after temperature compensation by the temperature compensating means. It is characterized by

Then, a sealing means for completely sealing the container to be inspected while the contents are contained therein, and the container sealed by the sealing means is pressurized and filled with an inert gas to a predetermined pressure. Gas filling means, an absolute pressure detection sensor for detecting the gas pressure in the container under pressure filled by the gas filling means, a temperature detecting means for detecting the temperature in the container for inspection, and the absolute pressure Temperature compensating means for compensating the gas pressure detected by the detection sensor based on the temperature detected by the temperature detecting means; storage means for storing the gas pressure after temperature compensation by the temperature compensating means; And a determination unit that determines the leaked state of the inspected container based on the change over time of the gas pressure stored in the storage unit.

[0017]

The absolute pressure detecting sensor according to the present invention operates as follows.

The absolute pressure detecting sensor is connected to the first chamber, which is cut off from the outside and kept at a constant pressure, in the casing, one of which is opened, and the second chamber, which has the same pressure as the outside pressure. The partition is arranged so as to form a chamber, and the partition is configured to be deformable according to the pressure difference between the pressure in the first chamber and the pressure in the second chamber. The partition wall is deformed according to the pressure difference with the pressure in one chamber. The pressure detection means outputs an electric signal according to the degree of this deformation. Therefore, the external absolute pressure can be detected by the level of this electric signal.

Specifically, the pressure detecting means is a semiconductor strain sensor whose resistance value changes according to the deformation amount of the partition wall, and a resistor which always exhibits a constant resistance value regardless of the deformation amount. And are alternately electrically bridge-connected, the above electric signal becomes an unbalanced voltage of the bridge circuit which becomes unbalanced according to the deformation state of the partition wall.

Further, the container leakage state inspection apparatus according to the present invention generally operates as follows. The sealing means completely seals the container to be inspected while the contents are contained. The gas filling means pressurizes and fills the container sealed by the sealing means with an inert gas to a predetermined pressure. Then, the absolute pressure detection sensor detects the gas pressure in the container to be inspected that is pressurized and filled by the gas filling means, and the storage means stores the gas pressure at every predetermined time detected by the absolute pressure detection sensor. .

Further, the judging means judges the leaked state of the container to be inspected based on the change with time of the gas pressure stored in the storage means.

Further, in view of the fact that the pressure in the tank changes due to the temperature change during measurement, temperature compensation means for detecting the temperature in the container to be inspected is provided when compensating for the influence of the temperature change. . In this case, the temperature compensating means temperature-compensates the gas pressure detected by the absolute pressure detecting sensor based on the temperature detected by the temperature detecting means, and the gas after temperature compensation by the temperature compensating means is performed. The pressure is stored in the storage means. Then, the judging means judges the leaked state of the inspected container based on the change over time of the gas pressure stored in the storage means.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a container leakage state inspection device according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the configuration of an absolute pressure detection sensor according to the present invention. The absolute pressure detection sensor 10 can detect the external absolute pressure with extremely high accuracy.

The cross section of the absolute pressure detecting sensor 10 is as shown in FIG.

In this pressure detection sensor 10, two chambers are formed in the case 12 by the partition wall 14. Of the two chambers, the first chamber 16 that is completely shielded from the outside by the partition wall 14 seals the closing member 18 that constitutes one end surface of the case 12 in the atmosphere with a coating material as illustrated. To be formed. By doing so, the pressure of the first chamber 16 is always kept at the atmospheric pressure at the time of sealing. The other chamber formed by the partition wall 14 and the case 12, that is, the second chamber 18, is a chamber for introducing atmospheric pressure through an open hole, and in the embodiment described later, a pressure introducing pipe 20. The pressure in the tank of the tank truck is introduced via.

A semiconductor sensor 22 which enables highly accurate pressure measurement is attached to the partition wall 14. The semiconductor sensor 22 is composed of a strain sensor manufactured by double diffusion on a silicon wafer and a fixed resistor. The semiconductor sensor 22 is configured so that even a very small strain can be taken out as an electric signal. In the figure, the distance between the partition wall 14 and the case 12 on the pressure introducing pipe side is exaggeratedly enlarged, but in reality, it is a minute distance of about 0.15 mm. The semiconductor sensor 22 is connected to the case 12 via a platinum lead wire.
Are connected to a stem electrode 24 fixed in an insulated state, and this electrode 24 is connected to an external computer or the like.

Incidentally, FIG. 7B shows the absolute pressure detection sensor 10 as seen from the mounting direction of the stem electrode 24. Although this figure shows an example in which six stem electrodes are attached, it is usually used to extract signals from four of these stem electrodes, and in the case of special use, six stem electrodes are used. Electrodes are used. FIG. 2 is a diagram showing a detailed configuration of the semiconductor sensor 22. The strain sensors 32A and 32B and the fixed resistors 34A and 34B are formed on the silicon wafer 30 by double diffusion as shown in the figure, and the strain sensor 32A, the fixed resistor 34A, and the strain sensor 32B are formed adjacent to each other. The fixed resistor 34B is connected to the connecting wires 35A, 35.
It is bridge-connected by B, 35C and 35D.
Although not shown, these connecting lines 35A, 35B,
Each of 35C and 35D is the stem electrode 2 shown in FIG.
4 connected to each.

The silicon wafer 30 also constitutes the partition wall 14, and is deformed according to the pressure difference between the first chamber 16 and the second chamber 18. This silicon wafer 30
The deformation of the strain sensor 32A and the strain sensor 3
Since the resistance value of 2B is different, the strain sensor 3
The equilibrium state of the bridge formed by 2A, the fixed resistor 34A, the strain sensor 32B, and the fixed resistor 34B collapses, and a voltage corresponding to the amount of deformation appears at the stem electrode 24. A computer or the like connected to the stem electrode 24 will detect the pressure with very high accuracy based on this voltage.

The pressure detection sensor 10 is for measuring absolute pressure. First chamber 16 as described above
When the level of the electric signal output from the semiconductor sensor 22 when forming is stored in the microcomputer as the initial pressure, the absolute pressure is detected by detecting the difference from the reference value. Can be detected. By doing this, the sensor design,
Manufacturing becomes very easy, and at the same time, it becomes possible to realize a sensor that can perform high-accuracy measurement at low cost.

FIG. 3 is a schematic configuration diagram of a tank truck in which a leak state is inspected by the absolute pressure detection sensor described above. Further, FIG. 2 is an explanatory view when the container leakage state inspection device using the absolute pressure detection sensor is attached to the tank truck.

The tank of the tank truck 40 is partitioned into a plurality of chambers (hereinafter, each of these chambers will be referred to as a tank independently) by a plurality of partition plates 42 provided inside the tank truck 40. The wave preventing plate 44 is provided so as to reduce waviness of the contained liquid or the like. A manhole 46 is attached to the upper part of each tank formed by the partition plate 42, and when a load is stored in this tank, the inlet 48 formed in this manhole is opened. The manhole 46 is provided with a safety valve 50 that prevents the pressure of the tank from being destroyed when the pressure in the tank becomes higher than a predetermined value. In addition, the manhole 46 has a measuring port 52.
Although the measuring port 52 is also provided, the measuring port 52 is used when the measuring rod 54 is inserted to measure the liquid amount in each tank. In the device of the present invention, this measuring port 52 is used at the time of measurement.

The apparatus of the present invention is attached to the measuring port 52 provided in the manhole 46 of the tank truck 40 as shown in FIG. The plug 60 is first inserted into the measuring port 52. Then, the screw formed on the stopper plug 60 and the screw formed on the measuring port 52 are engaged with each other. Next, the sensor portion 61, which is the main part of the present invention, is attached by engaging the screw provided on the sensor portion 61 with the screw formed on the plug plug 60, and the measuring port 52 is completely sealed. Since this plug plug 60 is provided with a release valve 62 to which a one-touch socket is attached, it cannot be said that it is in a completely sealed state as it is, but this release valve 62 has a cylinder filled with nitrogen gas. 63 is attached via a hose 64. In this state, the tank as the container to be inspected having the manhole 46 is completely shut off from the outside.

Although nitrogen gas is exemplified as the inert gas in this embodiment, it is needless to say that it is not limited to this. A hose 64 that connects the cylinder 63 and the release valve 62 is provided with a pressure reducing valve 65 and a safety valve 66.
This is to raise the tank to a predetermined pressure, and to prevent the occurrence of an accident at the time of an abnormality. After the measurement is completed, a release plug 67 is attached to the release valve 62 in place of the hose 64 so that the nitrogen gas filled in the tank is emitted into the atmosphere with low noise. In the above configuration, the measuring port 52, the plug 60, the sensor unit 6
1, the release valve 62 constitutes a sealing means, and the cylinder 6
3, the hose 64, the pressure reducing valve 65, and the safety valve 66 constitute gas filling means.

The sensor unit 61 functioning as an absolute pressure detection sensor is provided with a sensor and a microcomputer necessary for measurement. The sensor unit 61 is provided with two temperature sensors 68 and 69 connected to the outside via lead wires. Here, among the temperature sensors, the temperature sensor located above the tank when the sensor unit 61 is attached is referred to as an upper temperature sensor 68, and the temperature sensor located below is referred to as a lower temperature sensor 69. These temperature sensors 68 and 69 function as temperature detecting means. As shown in FIGS. 4 and 5, a power switch 70, a connector 71 for outputting accumulated measurement data to an external device, a measurement temperature display section 72, and a measurement pressure display section 73 are provided on the upper surface of the sensor section 61, respectively. It is provided.

In this embodiment, the temperature sensor is 2
Since there are two, each of the measured temperatures is displayed on the measured temperature display section 72. Further, a high-precision pressure sensor that detects the pressure in the tank via the plug 60 is built in the sensor unit 61, and the temperature is detected based on the detected values from the pressure sensor and the temperature sensor. There is also a built-in microcomputer that calculates the tank pressure after compensation and stores the calculated value at predetermined time intervals.

As an example of an external device connected to the connector 71 of the sensor section 61 as needed, a recorder as shown in FIG. 6 can be cited. This recorder 8
Reference numeral 0 indicates that the measurement data stored in the microcomputer of the sensor unit 61 is read out and displayed on the display unit 81 or printed out as necessary. Commands such as reading and printing out are performed by the keys arranged on the operation unit 82. The recorder 80 does not need to be connected during the measurement of the tank pressure by the sensor unit 61, and after transferring the measurement data stored in the microcomputer after the measurement,
Only this recorder can analyze the measurement data.

FIG. 7 is a block diagram of a control system of the container leakage state detecting device according to the present invention. A semiconductor sensor 22 in the figure measures a change in pressure inside the tank,
The upper temperature sensor 68 and the lower temperature sensor 69 respectively measure the temperatures of the upper and lower parts in the tank. C
PU100, according to the program stored in advance,
The detection data detected by each of the above sensors is processed or stored in the RAM 102 as it is. The recorder 80 has a sensor unit 61 if necessary.
Connected to the connector 71 provided in the RAM 102
It reads out the measurement data stored in and prints out or displays the data. In addition, necessary statistical processing and data printing can be performed by operating the keys provided on it.

The container leakage state inspection device of the present invention constructed as described above operates as follows in accordance with the flowcharts of FIGS. 8 and 9. Figure 8
The flowchart shown in is a flowchart which is processed when pressure measurement is performed. As a premise for this measurement, it is assumed that the sensor unit 61 is attached to the metering port 52 of the tank truck and that the tank is filled with nitrogen gas at a predetermined pressure. When the measurement start command is output in this state, first, the CPU 100 and all the elements and sensors connected thereto are initialized (S
1) The CPU 100 inputs the pressure in the tank detected by the semiconductor sensor 22 (S2) and simultaneously inputs the temperature detected by the upper temperature sensor 68 and the lower temperature sensor 69 (S2, S3). , These input values are temporarily stored in the RAM 102.

Next, the CPU 100 corrects and calculates the pressure detection value detected by the semiconductor sensor based on the temperatures detected by the both temperature sensors (S5), and stores the corrected value in the RAM 102 ( S6). The recording process of the above measurement data is performed at every predetermined data collection time, and this data collection is performed until the measurement time ends (S7, S8). In the above embodiment, the actually operating device has a measurement time of 60 minutes in step S7, and the data collection time of S8 is every 5 minutes from the start of measurement. Therefore, 12 points of measurement data can be obtained in an actual device.

Next, the flow chart shown in FIG. 9 relates to the operation of the recorder 80. When the recorder 80 is connected to the connector 71 of the sensor unit 61 and a command to transfer the data stored in the RAM 102 is output, the measurement data stored in the RAM 102 is measured by the CPU 100 and the CPU built in the recorder 80. It is transferred to the recorder 80 (S11). next,
The transferred data is analyzed according to the operation of various keys provided on the recorder 80 (S1
2) If there is a print command, the above analysis result is printed out based on the command (S13, S14).
This analysis result is, specifically, the detected pressure for each time series,
It is the detection temperature, the pressure fluctuation value within the measurement time (after temperature compensation), and the judgment result.

As described above, according to the container leakage state inspection apparatus of the present invention, it is not necessary to perform the conventional work of once extracting the contents in the tank and then filling it with water. It is very simple, and the measurement is performed almost completely automatically, and the analysis is done automatically by the computer, so there is no measurement error and the temperature compensation The reliability of the measurement data is very high. Further, since the obtained measurement data is digital data, it can be easily stored and becomes very useful basic data for later data analysis.

[0043]

As described above, according to the apparatus of the present invention, the container to be inspected is filled with the inert gas, and the leakage state of the container is detected based on the change with time of the gas pressure in the container. Therefore, the measurement work can be performed quickly regardless of the type of contents in the container. Further, since the absolute pressure detection sensor having a structure capable of high precision measurement is used for the measurement, the measurement can be performed with extremely high precision, and the reliability of the determination of the leakage state is improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an absolute pressure detection sensor of the present invention.

FIG. 2 is a diagram showing a configuration of a semiconductor sensor portion of the sensor shown in FIG.

FIG. 3 is a schematic configuration diagram of a commonly used tank truck.

FIG. 4 is an explanatory diagram of a measuring operation of the container leakage state inspection device according to the present invention.

FIG. 5 is an external view of a sensor portion of the leakage state inspection device for a container according to the present invention.

FIG. 6 is an external view of a recording / calculating device in the leakage state inspection device for a container according to the present invention.

FIG. 7 is a block diagram showing a configuration of a control system of the container leakage state inspection device according to the present invention.

8 is an operation flowchart showing a measurement process of the apparatus shown in FIG.

9 is an operation flowchart showing data processing of the apparatus shown in FIG.

[Explanation of symbols]

10 ... Pressure detection sensor, 14 ... Partition wall, 16 ... First chamber, 18 ...
Second chamber, 22 ... Semiconductor sensor, 3
0 ... Silicon wafer, 32A, 32B ... Strain sensor,
40 ... Tank truck, 52 ... Measuring port,
61 ... Sensor part, 63 ... Cylinder, 68, 69 ... Temperature sensor, 80 ... Recorder, 85 ...
Pressure detection sensor, 100 ... CPU,
102 ... RAM.

Claims (6)

[Claims] 1. A first chamber, which is cut off from the outside and kept at a constant pressure, and a second chamber, which communicates with the outside and exhibits the same pressure as the outside pressure, are formed in a casing of which one side is open. The partition is configured to be deformable according to the pressure difference between the pressure in the first chamber and the pressure in the second chamber, and the partition has an electric signal corresponding to the amount of deformation. An absolute pressure detection sensor characterized in that a pressure detection means for outputting is provided. 2. The pressure detecting means includes a semiconductor strain sensor whose resistance value changes in accordance with the deformation amount of the partition wall, and a resistor which always exhibits a constant resistance value regardless of the deformation amount. The absolute pressure detection sensor according to claim 1, wherein the absolute pressure detection sensor is configured so as to be electrically bridged alternately. 3. Sealing means for completely sealing the container to be inspected in a state where the contents are contained, and the container sealed by the sealing means is pressurized and filled with an inert gas to a predetermined pressure. A gas filling means, an absolute pressure detection sensor for detecting the gas pressure in the container under pressure filled by the gas filling means, and a gas pressure for each predetermined time detected by the absolute pressure detection sensor are stored. A leak state inspection device for a container, comprising: storage means. 4. A sealing means for completely sealing the container to be inspected in a state where the contents are contained, and the container sealed by the sealing means is pressurized and filled with an inert gas to a predetermined pressure. A gas filling means, an absolute pressure detection sensor for detecting the gas pressure in the container under pressure filled by the gas filling means, and a gas pressure for each predetermined time detected by the absolute pressure detection sensor are stored. A leak state inspection device for a container, comprising: a storage unit; and a determination unit that determines a leak state of the inspected container based on a change over time of a gas pressure stored in the storage unit. 5. Sealing means for completely sealing the container to be inspected in a state where the contents are accommodated, and the container sealed by the sealing means is pressurized and filled with an inert gas to a predetermined pressure. Gas filling means, an absolute pressure detection sensor for detecting the gas pressure in the container under pressure filled by the gas filling means, a temperature detecting means for detecting the temperature in the container for inspection, the absolute pressure It has a temperature compensating means for compensating the gas pressure detected by the detection sensor based on the temperature detected by the temperature detecting means, and a storing means for storing the gas pressure after temperature compensation by the temperature compensating means. An apparatus for inspecting leakage state of a container, which is characterized in that 6. Sealing means for completely sealing the container to be inspected in a state where the contents are accommodated, and the container sealed by the sealing means is pressurized and filled with an inert gas to a predetermined pressure. Gas filling means, an absolute pressure detection sensor for detecting the gas pressure in the container under pressure filled by the gas filling means, a temperature detecting means for detecting the temperature in the container for inspection, the absolute pressure Temperature compensating means for compensating the gas pressure detected by the detection sensor based on the temperature detected by the temperature detecting means; storage means for storing the gas pressure after temperature compensation by the temperature compensating means; A leakage state inspection device for a container, comprising: a determination unit configured to determine a leakage state of the container to be inspected based on a temporal change in gas pressure stored in the storage unit.