JP2010151199A - Liquid quantity display of liquefied gas tanker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid quantity display of liquefied gas tanker which can display an exact liquid quantity and check an oil level at a location distant from the tank. <P>SOLUTION: Owing to a portable information terminal 7 which has a differential pressure data output means 5 for outputting differential pressure data as an electric signal by detecting a pressure difference between an upper part pressure and a lower part pressure within a tank 2 of a liquefied gas tanker 1, an operation part 12 operating the liquid quantity within the tank 2 based on the differential pressure data output, and a display part 13 displaying the operated liquid quantity, the liquid quantity within the tank 2 is operated by outputting the differential pressure data within the tank 2 as the electric signal. Consequently, the number of mechanical operating parts is few unlike conventional analog-type liquid level indicators and, it is hard to break even at vibration application, resulting in stable movement. Therefore, maintenance becomes easy drastically, and cost becomes low sharply. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid level display device for a liquefied gas tank truck that can store an ultra-low temperature liquefied gas such as liquefied natural gas, which is mainly a hydrocarbon fuel gas, and transport it to a desired location.

As a liquid level gauge for liquefied gas such as liquefied natural gas, since the liquefied gas is generally at a very low temperature, a differential pressure type liquid level gauge that can be used even in a low temperature environment is used. In a tank lorry for transporting liquefied gas, since the tank is not equipped with a power source, an analog type liquid level gauge having a mechanical operating part such as a spring is disposed in the rear door of the tank as the liquid level gauge ( For example, the following patent document 1).
JP-A-11-32433 JP 2004-123229 A JP 2002-302200 A

  However, in the liquid level gauge of Patent Document 1, when it is necessary to read the amount of liquid in the tank, the tank truck driver or the operator who transfers and fills the liquefied gas goes to the rear door of the tank. Since the gauge must be read visually, the reading work is inconvenient, and the liquid volume cannot be known in real time, so in the unlikely event that liquid leaks, it may be delayed to notice .

  In addition, since the tank lorry tank is a mobile container, analog level gauges that detect minute pressure differences at the machine operating part are fragile due to vibration of the moving tank, etc. The fact is that it needs to be exchanged again and again. In addition, analog level gauges as described above are very expensive, and in recent economic circumstances, manufacturers of liquid level gauges have withdrawn from work, and transport of liquefied gas by tank trucks has occurred. The situation is likely to affect the business itself.

  On the other hand, the system of Patent Document 2 is disclosed as a system for transmitting the liquid level in the tank, and the system of Patent Document 3 is disclosed as a system for calculating the flow rate of the tank truck.

  However, when the liquefied gas transported by the tank truck is liquefied natural gas, the composition of the liquefied natural gas is not constant depending on the production area of the natural gas, the liquid density also varies, and the characteristics of the ultra-low temperature liquefied gas As a result, the liquid density varies depending on the liquid temperature and pressure. However, in the above conventional liquid level gauge, the scale is fixed, so even if liquefied gases with different liquid densities are stored, the same scale must be read, and the scale of the liquid level gauge accurately indicates the liquid level in the tank. There was a problem that it was not reflected. In order to know the exact amount of liquid in this state, it is necessary to create a correction conversion table for each natural gas production area, liquid temperature, and pressure, and to correct the scale read visually. Due to the complexity, this is not actually done.

  Further, in practice, trading is performed by measuring weight, not volume. The High Pressure Gas Safety Law prohibits loading of 90% or more of the container's internal volume, but weight measurement management is difficult to respond to changes in liquid density, and it is difficult to say that this loading standard can always be guaranteed. There may also be security problems. The systems described in Patent Documents 2 and 3 cannot solve these problems.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a liquid level display device for a liquefied gas tank tank capable of reflecting an accurate liquid amount and confirming a liquid level at a position away from the tank. And

  In order to achieve the above object, a liquid level display device for a liquefied gas tank truck according to the present invention detects a pressure difference between an upper pressure and a lower pressure in a tank of a liquefied gas tank truck and outputs differential pressure data as an electrical signal. The gist is provided with data output means, liquid amount calculation means for calculating the liquid amount in the tank based on the output differential pressure data, and display means for displaying the calculated liquid amount.

  That is, the present invention provides a differential pressure data output means for detecting an upper pressure and a lower pressure in a tank of a liquefied gas tank lorry and outputting differential pressure data as an electrical signal, and a tank based on the output differential pressure data. Liquid amount calculating means for calculating the amount of liquid and display means for displaying the calculated liquid amount. In this way, because the differential pressure data in the tank is output as an electrical signal and the amount of liquid in the tank is calculated, there are few machine operating parts like the conventional analog level gauge, so depending on the operation of the vehicle Even if vibration is applied, it is hard to break and the operation is stable. For this reason, the maintenance becomes much easier and the cost is greatly reduced.

  In the present invention, the liquid amount calculation means receives input of liquid density information related to the liquid density of the liquefied gas stored in the tank, and based on the liquid density and differential pressure data corresponding to the received liquid density information. When calculating the liquid volume, the liquid volume in the tank is calculated based on the liquid density and the differential pressure. Therefore, the liquid volume calculated by the liquid volume calculation means and displayed on the display means is the liquid volume in the tank. Is reflected very accurately. Therefore, for example, when the liquefied gas is liquefied natural gas, the amount of liquid is calculated based on the density corresponding to the natural gas production area. Even when the pressure is different, it is possible to reflect the exact amount of liquid in the tank. For this reason, the inconvenience of the distribution cost in the case of transporting with a tank truck is eliminated, and the error when it is actually gas is almost eliminated, and it is possible to trade with an accurate gas amount. In addition, safety is ensured. In this case, for example, the input of the production area information of the natural gas stored in the tank as the liquid density information is received, and the liquid amount in the tank is calculated based on the liquid density corresponding to the production area of the received production area information. It is also possible to perform calculation using the liquid density obtained by analysis.

  In the present invention, the differential pressure data output means is provided in the tank, and the liquid amount calculation means and the display means are provided in a portable information terminal that can be separated from the tank and the tow vehicle. When wireless transmission means for wirelessly transmitting the differential pressure data output from the output means to the portable information terminal is provided, the inside of the tank calculated by the liquid amount calculation means and displayed on the display means Can be known from a portable information terminal that can be separated from the tank and the towing vehicle. For this reason, even if you do not bother to go to the rear door of the tank, check the amount of liquid in the tank in real time at a place away from the tank such as the driver's seat, office, rest area, etc. Can do. Therefore, it is possible to check and monitor the amount of liquid in the tank at any time while moving or stopping, so even if a liquid level abnormality such as liquid leakage occurs, you can immediately know it and prevent accidents in advance. Correspondence becomes possible.

  In the present invention, the wireless transmission means receives the differential pressure data from the differential pressure data output means provided in the tank via a relay connector and a data transmission cable, and the received differential pressure data is transmitted to the portable information terminal. On the other hand, when configured to wirelessly transmit, differential pressure data is reliably transmitted from the differential pressure data output means to the wireless transmission means, and the data transmission cable can be disconnected and connected at the relay connector portion. Therefore, even when the tank is disconnected from or connected to the towing vehicle, it can be handled without problems.

  In the present invention, when the differential pressure data output means provided in the tank is configured to be supplied with power from a power supply unit provided in the towing vehicle via a relay connector, Since no power source is originally provided, differential pressure data can be output as an electrical signal without bothering to provide a power source for the tank.

  In the present invention, the calculated “liquid amount” includes all values such as liquid volume (for example, liter), liquid weight (for example, ton), liquid level (for example, cm), and differential pressure (for example, kPa). It is the purpose.

  Next, the best mode for carrying out the present invention will be described.

  FIG. 1 and FIG. 2 are diagrams showing an embodiment of a liquid amount display device for a liquefied gas tank truck to which the present invention is applied.

  The liquid amount display device is a device that displays the liquid amount in the tank 2 in a tank truck 1 that includes a tank 2 that stores liquefied gas and a towing vehicle 3 that pulls the tank 2.

  The liquid amount display device includes a differential pressure data output means 5, a wireless transmission means 6, and a portable information terminal 7.

  The differential pressure data output means 5 is provided in the tank 2, detects the pressure difference between the upper pressure and the lower pressure in the tank 2 of the liquefied gas tank truck 1, and outputs the differential pressure data as an electrical signal. The internal pressure data of the upper part of the tank 2 is detected and the internal pressure data is output as an electric signal.

  The portable information terminal 7 can be separated from the tank 2 and the towing vehicle 3 and serves as a liquid amount calculation means for calculating the amount of liquid in the tank 2 based on the differential pressure data output from the differential pressure data output means 5. A calculating unit 12 that functions and a display unit 13 that functions as display means for displaying the calculated liquid amount are provided.

  The traction vehicle 3 is provided with wireless transmission means 6 for wirelessly transmitting the differential pressure data output from the differential pressure data output means 5 to the portable information terminal 7.

  The wireless transmission means 6 receives the differential pressure data from the differential pressure data output means 5 provided in the tank 2 via the relay connector 9 and the data transmission cable 10, and uses the received differential pressure data as the portable information terminal. 7 is transmitted wirelessly.

  More specifically, as the differential pressure data output means 5, for example, a differential pressure transmitter can be used. For example, a differential pressure for detecting a pressure difference between an upper side pressure and a lower side pressure inside the tank 2. A sensor 23 and an internal pressure sensor 24 for detecting the pressure (internal pressure) on the upper side inside the tank 2 are provided.

  In the differential pressure data output means 5, the differential pressure sensor 23 detects the pressure on the upper side and the lower side in the tank 2 through, for example, a diaphragm seal or a capillary tube, and detects the differential pressure. Data is output from the data transmission cable 10 as an electrical signal (for example, a current of 4 to 20 mA in this example). The differential pressure data can be converted into a differential pressure value such as kPa and displayed on the display 25 provided in the differential pressure data output means 5.

  In the differential pressure data output means 5, the internal pressure sensor 24 detects the pressure inside the tank 2 through, for example, a diaphragm seal or a capillary tube to detect the pressure value, and the internal pressure data is The signal is output from the data transmission cable 10 as a signal (for example, a current of 4 to 20 mA in this example). The internal pressure data can be converted into an internal pressure value such as kPa and displayed on the display 25 provided in the differential pressure data output means 5.

  The wireless transmission means 6 is connected to the network board 18 to which the differential pressure data and the internal pressure data output from the differential pressure data output means 5 through the data transmission cable 10 are input, and is connected to the network board 18 so that the input And a wireless LAN access point 19 for wirelessly transmitting the differential pressure data and the internal pressure data via the external antenna 20. The wireless transmission means 6 is supplied with power from a power supply unit 11 for an automobile provided in the towing vehicle 3 and can use the supplied power (for example, 24V) on the network board 18 (for example, 5V). A transformer 21 is provided for transforming.

  The wireless transmission means 6 includes a power cable 22 for supplying the supplied power of the power supply unit 11 as the power of the differential pressure data output means 5 via the relay connector 9. Thus, the differential pressure data output means 5 provided in the tank 2 is configured to be supplied with power from the power supply unit 11 provided in the traction vehicle 3 via the relay connector 9.

  The relay connector 9 can connect and disconnect the power cable 22 and the data transmission cable 10. When the tank 2 is disconnected from the towing vehicle 3, the relay connector 9 is disconnected. When the tank 2 is connected to the towing vehicle 3, the relay connector 9 is relayed. The connector 9 is connected.

  The portable information terminal 7 includes a transmitter / receiver 14 for receiving and controlling differential pressure data and internal pressure data wirelessly transmitted from the wireless transmitter 6, and a liquid in the tank 2 based on the differential pressure data received by the transmitter / receiver 14. A calculation unit 12 that functions as a liquid amount calculation unit that calculates the amount and a display unit 13 that functions as a display unit that displays necessary information including the calculated liquid amount are provided.

  The portable information terminal 7 includes an input unit 17 for inputting necessary information including liquid density information related to the liquid density of the liquefied gas stored in the tank 2. The liquid density information input by the input unit 17 is received by the calculation unit 12, and the liquid amount in the tank 2 is calculated based on the liquid density and differential pressure data corresponding to the liquid density information received by the calculation unit 12.

  The portable information terminal 7 includes a storage unit 15 and a storage unit 16. A program stored in the storage unit 16 is expanded in the storage unit 15, and the above transmission / reception and calculation are performed under the control of the program. At the same time, the control described later is executed.

  For example, when a numerical value of liquid density data is input as the liquid density information input by the input unit 17, the calculation unit 12 determines the amount of liquid in the tank 2 based on the input liquid density data and the received differential pressure data. Is calculated.

Further, when the liquefied gas stored in the tank 2 is liquefied natural gas, the liquid density of the liquefied natural gas varies depending on the production area of the natural gas. For example, Alaska (Kenai) production is 420.0kg / ^{m 3,} Brunei (Lumut) production is 463.7kg / ^{m 3,} East Kalimantan, Indonesia (Bontang) production is 455.0kg / ^{m 3,} Indonesia North Sumatra (Arun) production Is 454.3 kg / m ³ , Australia (Wisnel Bay) is 464.5 kg / m ³ , Malaysia (Bintulu) is 464.2 kg / m ³ , Qatar (Rasraphan) is 457.4 kg / m ³ (Source) : LNG Small Base Japan Gas Association, Japan Gas Association December 2000, P.1).

  Therefore, for example, the production area information and the liquid density data are associated with each other and stored in the storage unit 16 in advance, and the input of the natural gas production area information is received as the liquid density information input by the input unit 17. The liquid density data corresponding to the production area is read from the storage unit 16 based on the above, and the calculation unit 12 calculates the liquid amount in the tank 2 based on the read liquid density data and the received differential pressure data. Also good.

  In the above-described calculation, the calculated “liquid amount” is calculated to a value such as a liquid volume (for example, liter), a liquid weight (for example, ton), a liquid level (for example, cm), and a differential pressure (for example, kPa). The liquid amount calculated as described above is displayed on the display unit 13.

  As the portable information terminal 7, for example, a PDA terminal, a small notebook personal computer or the like can be used.

  3-5 is a figure which shows an example of the display screen of the display part 13 of the said portable information terminal 7. As shown in FIG. Hereinafter, the operation of the liquid amount display device of the present invention will be described with reference to these display screens.

  First, when the power of the wireless transmission means 6 is turned on, power is supplied from the power supply unit 11 to the wireless transmission means 6, and the differential pressure data is output via the wireless transmission means 6 via the power cable 22 and the relay connector 9. The means 5 is also supplied with power. Thereby, the output of the differential pressure data and the internal pressure data is started from the differential pressure data output means 5, and the differential pressure data and the internal pressure data are received by the wireless transmission means 6 via the data transmission cable 10 and the relay connector 9. At this time, the differential pressure data and the internal pressure data are displayed on the display 25 of the differential pressure data output means 5.

  Next, when the mobile information terminal 7 is turned on, a startup screen shown in FIG. 3 is displayed on the display unit 13. On this startup screen, a liquid level monitor start button 27 and a liquid density change button 28 are displayed.

The liquid density change button 28 displays the liquid density that was set at the time of activation, that is, immediately before the previous end. In this example, 420.0 (kg / m ³ ) is set and displayed. When changing the set liquid density, an input operation of touching the liquid density change button 28 with a touch pen is performed.

  In this example, an example in which a PDA terminal is used as the portable information terminal 7 is described, and the display unit 13 is a screen that also serves as a touch panel as the input unit 17, and a predetermined display displayed on the screen. A desired input operation can be performed by touching the position of the button with a touch pen. A selection button and an input button as the input unit 17 including the OK button 31 are also arranged below the display unit 13, and an input operation is performed using these selection buttons and input buttons as necessary. You can also.

When an input operation for touching the liquid density change button 28 with a touch pen is performed, a liquid density setting screen shown in FIG. 4 is displayed on the display unit 13. On this liquid density setting screen, a numeric keypad 29 and a liquid density display unit 30 are displayed. When liquid density data is input by touching each numeric key of the numeric keypad 29 with a touch pen, the input liquid density data is displayed as a liquid density display. Displayed on the unit 30. In this example, 463.7 (kg / m ³ ) is input and displayed. After inputting the liquid density data, for example, when the OK button 31 is pressed, the liquid density data input here is set to be used for the subsequent liquid volume calculation, and the liquid volume calculation is started.

  Here, when the liquid density is not changed on the start-up screen shown in FIG. 3, the liquid level monitor start button 27 on the start-up screen is touched with a touch pen, and calculation of the liquid amount is started using the already set liquid density. Is done. That is, the differential pressure data and the internal pressure data output from the differential pressure data output unit 5 are received by the wireless transmission unit 6, wirelessly transmitted by the wireless LAN, and received by the portable information terminal 7. Then, the liquid amount is calculated by the calculation unit 12 based on the received differential pressure data and the set liquid density data.

  At this time, when calculating the liquid weight (for example, ton) as the liquid amount, it is calculated from the differential pressure data and the liquid density data, and when calculating the liquid level (for example, cm), it is added to the differential pressure data and the liquid density data. The calculation is performed using data on the capacity, inclination angle, radius, structure, etc. of the tank 2. At this time, it is also possible to detect the ambient temperature and perform correction in consideration of the variation of the liquid density due to the ambient temperature.

  FIG. 5 shows a display screen of the liquid amount and the internal pressure. When the liquid level monitor start button 27 is touched with the touch pen on the startup screen of FIG. 3 or the liquid density data is input on the liquid density setting screen of FIG. 4 and the OK button 31 is pressed, the calculation of the liquid amount is started. The liquid amount and the received internal pressure are displayed on the display unit 13.

  In FIG. 5A, the liquid amount is calculated as weight (ton) and liquid level (m) and displayed together with the internal pressure data (MPa) received from the differential pressure data output means 5. In this example, the liquid volume is 13.4 ton by weight, the liquid level is 1.76 m, the internal pressure is numerically displayed as 0.35 MPa, and the liquid volume level with respect to the full tank volume is displayed as a horizontal bar graph. . FIG. 5B is an example in which the level of the liquid amount relative to the full tank amount is displayed as a vertical bar graph. FIG. 5C shows the liquid volume as a numerical value of 8.28 kPa as a differential pressure and an internal pressure as 0.35 MPa, and also displays the level of the liquid volume relative to the full tank volume as an image of the indicating instrument. The level of the liquid amount with respect to the full tank amount is calculated using data regarding the liquid weight when the tank is full, the capacity of the tank 2, the tilt angle, the radius, the structure, and the like.

  The liquid volume and internal pressure display screen can accept a switching input by a touch pen or the like, and can switch the display of FIGS. 5A, 5B, and 5C as necessary.

  The above-described output of differential pressure data and internal pressure data from the differential pressure data output means 5, reception of differential pressure data and internal pressure data by the wireless transmission means 6, and wireless transmission by LAN are performed at any time while the power of the wireless transmission means 6 is turned on. Is called. The reception and calculation of the differential pressure data and the internal pressure data by the portable information terminal 7 and the display of the calculated fluid amount and the received internal pressure are performed for a predetermined time while the power of the wireless transmission means 6 and the portable information terminal 7 is ON. Every time (eg every 1 minute). Thereby, the liquid amount can be monitored periodically.

  At this time, the upper limit threshold and lower limit threshold of the liquid amount are set in advance, and when the calculated liquid amount exceeds the upper limit threshold or falls below the lower limit threshold, a screen notification for changing the color of the display of a graph or the like It is also possible to perform control so that an alarm is issued by notification such as voice notification that sounds.

  When the calculation and display are finished, the portable information terminal 6 is turned off and the wireless transmission means 6 is turned off.

  In the tank lorry 1 described above, when there are a plurality of tank lorries 1, the differential pressure data and the internal pressure data wirelessly transmitted by the wireless transmission means 6 are received by the portable information terminal 7 unique to each tank lorry 1 and the liquid amount is calculated. Alternatively, the differential pressure data and the internal pressure data of a plurality of tank trucks 1 may be received by one portable information terminal 7 and the liquid amount of each tank truck 1 may be calculated and displayed.

  FIG. 6 shows a state where the tank 2 is separated from the towing vehicle 3 in the tank lorry 1. Thus, when the tank 2 is disconnected from the towing vehicle 3, the relay connector 9 is disconnected and the data transmission cable 10 and the power cable 22 are disconnected. Then, by connecting the portable power source 8 to the relay connector 9 and supplying the power source 22 to the power cable 22, the differential pressure data output means 5 is operated in the tank 2 separated from the towing vehicle 3, and attached Data such as differential pressure can be confirmed on the display 25.

  FIG. 7 shows a computer connected to the receiving terminal 33 instead of receiving the differential pressure data and the internal pressure data wirelessly transmitted by the wireless transmitting means 6 in the tank truck 1 at the portable information terminal 7 unique to each tank truck 1. Received by device 32. For example, the differential pressure data and internal pressure data of a plurality of tank trucks 1 waiting in a parking lot or the like may be received by the computer device 32 installed in the office or the like, and the liquid amount of each tank truck 1 may be calculated and displayed. . Thereby, the liquid quantity of the plurality of tank trucks 1 waiting in the parking lot or the like can be monitored, and it should be possible to cope with any abnormal liquid level.

  FIG. 8 shows a state where the tank 2 is separated from the towing vehicle 3 in the tank lorry 1. Then, the wireless transmission means 6 to which the portable power supply 8 is connected is connected to the relay connector 9, and the power of the portable power supply 8 is supplied to the power cable 22 via the wireless transmission means 6. Then, the differential pressure data output means 5 is operated in the tank 2 separated from the towing vehicle 3, and the differential pressure data and the internal pressure data output by the differential pressure data output means 5 are transmitted by the wireless transmission means 6 via the data transmission cable 10. Receive. Furthermore, the differential pressure data and the internal pressure data wirelessly transmitted by the wireless transmission means 6 are received not by the portable information terminal 7 unique to each tank truck 1 but by the computer device 32 to which the receiving terminal 33 is connected. For example, the differential pressure data and internal pressure data of a plurality of tank trucks 1 waiting in a parking lot or the like may be received by the computer device 32 installed in the office or the like, and the liquid amount of each tank truck 1 may be calculated and displayed. . Thereby, the liquid quantity of the some tank 2 waiting in a parking lot etc. can be monitored, and when a liquid level abnormality should be coped with by any chance.

  As described above, according to the present embodiment, the differential pressure data output means 5 that detects the upper pressure and the lower pressure in the tank 2 of the liquefied gas tank truck 1 and outputs the differential pressure data as an electrical signal, and the above output. And a display section 13 as a display means for displaying the calculated liquid volume. The calculation section 12 is a liquid volume calculation means for calculating the liquid volume in the tank 2 based on the differential pressure data. As described above, since the differential pressure data in the tank 2 is output as an electrical signal and the amount of liquid in the tank 2 is calculated, there are few machine operating parts such as a conventional analog level gauge. It is hard to break even if vibrations from operation are applied, and the operation is stable. For this reason, the maintenance becomes much easier and the cost is greatly reduced.

  The computing unit 12 receives input of liquid density information related to the liquid density of the liquefied gas stored in the tank 2, and calculates the amount of liquid in the tank 2 based on the liquid density and differential pressure data corresponding to the received liquid density information. In the case of calculation, since the liquid amount in the tank 2 is calculated based on the liquid density and the differential pressure, the liquid amount calculated in the calculation unit 12 and displayed on the display unit 13 is the same as the liquid amount in the tank 2. Reflected very accurately. Therefore, for example, when the liquefied gas is liquefied natural gas, the amount of liquid is calculated based on the density corresponding to the natural gas production area. Even when the pressures are different, the exact amount of liquid in the tank 2 can be reflected. For this reason, the inconvenience of the distribution cost when transported by the tank lorry 1 is solved, and it becomes possible to trade with an accurate gas amount. In addition, safety is ensured. In this case, for example, input of the production area information of the natural gas stored in the tank 2 is received as the liquid density information, and the amount of liquid in the tank 2 is calculated based on the liquid density corresponding to the production area of the received production area information. The liquid density obtained by liquid analysis can also be used for calculation.

  The differential pressure data output means 5 is provided in the tank 2, and the calculation unit 12 and the display unit 13 are provided in the portable information terminal 7 that can be separated from the tank 2 and the towing vehicle 3. When wireless transmission means 6 for wirelessly transmitting the differential pressure data output from the pressure data output means 5 to the portable information terminal 7 is provided, it is calculated by the calculation unit 12 and displayed on the display unit 13. The displayed liquid amount in the tank 2 can be known from the portable information terminal 7 that can be separated from the tank 2 and the towing vehicle 3. For this reason, even if you do not bother to go to the rear door of the tank 2, the amount of liquid in the tank 2 can be measured in real time at a location away from the tank 2, such as a driver's seat, office, or rest area, as long as it is within radio range. Can be confirmed. Therefore, since the amount of liquid in the tank 2 can be checked and monitored at any time while moving or stopped, even if a liquid level abnormality such as liquid leakage occurs, it can be immediately known, and accidents can occur in advance. Preventive measures can be taken.

  The wireless transmission means 6 receives the differential pressure data from the differential pressure data output means 5 provided in the tank 2 via the relay connector 9 and the data transmission cable 10, and uses the received differential pressure data as the portable information terminal. 7, the differential pressure data is reliably transmitted from the differential pressure data output means 5 to the wireless transmission means 6, and the data transmission cable 10 is connected to the relay connector 9 portion. Since separation and connection are possible, it is possible to handle the tank 2 without any problem when it is disconnected from or connected to the towing vehicle 3.

  When the differential pressure data output means 5 provided in the tank 2 is configured to be supplied with power from the power supply unit 11 provided in the towing vehicle 3 via the relay connector 9, Since 2 does not originally have a power source, the differential pressure data can be output as an electrical signal without providing the tank 2 with a power source.

  In the above embodiment, the wireless LAN is used as the wireless transmission means. However, the present invention is not limited to this, and various wireless transmissions can be applied. Further, the liquefied gas to be applied is not limited to natural gas, and various liquefied gases can be applied.

  Further, the liquefied gas applicable to the present invention is not limited to hydrocarbon fuels such as liquefied natural gas, but other industrial gases such as liquefied oxygen, liquefied nitrogen, liquefied argon, liquefied carbon dioxide gas, etc. It is also possible to apply the liquefied gas.

It is a figure which shows one Embodiment of the liquid amount display apparatus of the liquefied gas tank truck of this invention. It is a system block diagram which shows the said liquid amount display apparatus. It is a figure which shows an example of the display screen of a portable information terminal. It is a figure which shows an example of the display screen of a portable information terminal. It is a figure which shows an example of the display screen of a portable information terminal. It is a figure which shows the 2nd usage example of the said liquid quantity display apparatus. It is a figure which shows the 3rd usage example of the said liquid quantity display apparatus. It is a figure which shows the 4th usage example of the said liquid quantity display apparatus.

Explanation of symbols

1: Tank truck 2: Tank 3: Traction vehicle 5: Differential pressure data output means 6: Wireless transmission means 7: Portable information terminal 8: Portable power supply 9: Relay connector 10: Data transmission cable 11: Power supply section 12: Calculation section 13: Display unit 14: Transmission / reception unit 15: Storage unit 16: Storage unit 17: Input unit 18: Network board 19: Wireless LAN access point 20: External antenna 21: Transformer 22: Power cable 23: Differential pressure sensor 24: Internal pressure sensor 25 : Display 27: Liquid level monitor start button 28: Liquid density change button 29: Numeric keypad 30: Liquid density display part 31: OK button 32: Computer device 33: Reception terminal

Claims (5)

Differential pressure data output means for detecting the pressure difference between the upper pressure and the lower pressure in the tank of the liquefied gas tank truck and outputting differential pressure data as an electrical signal;
A liquid amount calculating means for calculating a liquid amount in the tank based on the output differential pressure data;
A liquid level display device for a liquefied gas tank lorry, comprising display means for displaying the calculated liquid level.   The liquid amount calculation means receives input of liquid density information related to the liquid density of the liquefied gas stored in the tank, and calculates the liquid amount in the tank based on the liquid density and differential pressure data corresponding to the received liquid density information. The liquid amount display device for a liquefied gas tank truck according to claim 1. The differential pressure data output means is provided in the tank, and the liquid amount calculation means and the display means are provided in a portable information terminal that can be separated from the tank and the towing vehicle,
3. The liquefied gas tank truck according to claim 1, wherein the traction vehicle is provided with wireless transmission means for wirelessly transmitting the differential pressure data output from the differential pressure data output means to the portable information terminal. Liquid volume display device.   The wireless transmission means receives differential pressure data from a differential pressure data output means provided in the tank via a relay connector and a data transmission cable, and wirelessly transmits the received differential pressure data to the portable information terminal. The liquid amount display device of the liquefied gas tank truck according to claim 3, which is configured to do so.   The liquefied gas tank truck according to claim 3 or 4, wherein the differential pressure data output means provided in the tank is configured to be supplied with power from a power supply section provided in the towing vehicle via a relay connector. Liquid volume display device.

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