Level sensor inspection device and lift unit

Abstract

To provide a level sensor inspection device that can reduce a workload of a worker and can inspect whether or not a level sensor functions normally.SOLUTION: The invention relates to a level sensor inspection device used for inspection of a float-type level sensor which is provided in an upper portion of a liquid storage chamber of a liquid storage tank and which closes a bottom valve in the liquid storage chamber when a float rises. The level sensor inspection device includes: an air supply hose that conveys compressed air of a pressure higher than atmospheric pressure into the liquid storage chamber; and an air ejection pipe that is connected to a distal end portion of the air supply hose and ejects the compressed air to a lower portion of the level sensor from below the level sensor. The float can be raised by ejecting the compressed air from the air ejection pipe toward the float.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a level sensor inspection device for inspecting whether a level sensor installed in a liquid transport vehicle such as a tanker truck or an aircraft refueling truck is operating normally, and a lifting unit equipped with a level sensor inspection device. [Background technology]

[0002] Vehicles for transporting liquid fuel, such as tank trucks and aircraft refueling vehicles, have a liquid tank for storing liquid fuel. The liquid tank has a plurality of liquid storage chambers for storing liquid fuel, separated by partition walls, and each liquid storage chamber is equipped with a level sensor for preventing the injected liquid fuel from overflowing.

[0003] Some level sensors installed in the liquid storage chamber are composed of float-type reed switches. In this type of level sensor, when liquid fuel injected into the liquid storage chamber comes into contact with the float, the float rises. The magnetic force of a magnet embedded in the float magnetizes ferromagnetic metal pieces inside the reed switch, attracting them together and bringing them into contact. The contact between the metal pieces turns on and off various devices connected to the switch. In a float-type reed switch installed in the liquid storage chamber, when a certain amount of liquid fuel is injected into the liquid storage chamber and the float rises, the switch turns on, closing the bottom valve installed to inject liquid fuel into the liquid storage chamber, and stopping the injection of liquid fuel into the liquid storage chamber. In this way, the level sensor installed in the liquid storage chamber as a float-type reed switch can prevent the liquid fuel injected into the liquid storage chamber from overflowing. In other words, the level sensor installed in the liquid storage chamber functions as a safety net when liquid fuel is injected into the liquid storage chamber. Therefore, whether or not the level sensor functions properly plays a very important role in vehicles transporting liquid fuel, and it is mandatory to check whether or not the level sensor functions properly while pouring liquid fuel into the liquid storage chamber. Examples of level sensor inspection devices include those described in Patent Document 1 and Patent Document 2 below.

[0004] Patent Document 1 describes a level sensor inspection device that includes a first vertical pipe equipped with a liquid tank level sensor capable of detecting the liquid level, a second vertical pipe equipped with a scale and disposed outside the liquid tank opposite the first vertical pipe, and a horizontal pipe connecting the lower ends of the first and second vertical pipes. In this level sensor inspection device, it is possible to check whether the liquid tank level sensor is normal or not by injecting some kind of liquid through the horizontal pipe and comparing the scale on the second vertical pipe at the point where the liquid tank level sensor disposed in the first vertical pipe reacts.

[0005] Furthermore, Patent Document 2 describes a configuration in which a support leg is connected to the tip of a wire that can be pulled up from outside a tank that stores liquid fuel, and the float portion of a float-type reed switch can be operated from outside by operating the wire. In a float-type reed switch inspection device configured in this way, the float portion can be raised simply by pulling up the wire, making it possible to check whether the float-type reed switch is functioning normally without injecting liquid. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-18138 [Patent Document 2] Japanese Patent Application Publication No. 9-89634 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the technology of Patent Document 1 requires a liquid to check whether the level sensor is functioning normally. Therefore, the technology of Patent Document 1 cannot determine whether the level sensor is functioning normally unless some liquid is injected, and it cannot determine whether the level sensor is functioning normally while injecting liquid fuel into the liquid storage chamber.

[0008] Furthermore, although the technology of Patent Document 2 makes it possible to check whether the level sensor is functioning normally without injecting liquid into the liquid storage chamber, it is configured to determine whether the level sensor is functioning normally by rotating the pressing member to raise and lower the float, so if the pressing member that moves the float does not function normally due to some factor (for example, rust on the rotating shaft of the pressing member), it is not possible to determine whether the level sensor is functioning normally.

[0009] In addition, a conventional inspection method for checking whether the level sensor is functioning properly involves opening a manhole at the top of the storage tank and having an operator manually operate the level sensor through a hole formed in the storage tank. Directly operating the level sensor in this manner ensures that the level sensor is functioning properly. However, because the inspection is performed by opening the manhole in the storage chamber, there is a risk that the operator may inhale the liquid fuel, especially in the case of volatile liquid fuel, if the operator is asked to determine whether the level sensor is functioning properly while pouring the liquid fuel into the storage chamber. This creates a significant workload for the operator.

[0010] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a level sensor inspection device that can reduce the workload of workers and inspect whether a level sensor is functioning normally. [Means for solving the problem]

[0011] The level sensor inspection device of the present invention is a level sensor inspection device used to inspect whether a float-type level sensor, which is installed at the top of the liquid storage chamber of a liquid storage tank and closes the bottom valve in the liquid storage chamber when the float rises, is functioning normally, and is characterized in that it has an air supply hose that transports compressed air at a pressure higher than atmospheric pressure into the liquid storage chamber, and an air ejection pipe that is connected to the tip of the air supply hose and ejects the compressed air from below the level sensor to the bottom of the level sensor, and is capable of raising the float by ejecting the compressed air from the air ejection pipe onto the float.

[0012] Another aspect of the level sensor inspection device of the present invention is characterized in that a cylindrical sensor housing case is installed between the ceiling and bottom surfaces of the liquid storage chamber, and the level sensor and the air ejection pipe are provided inside the sensor housing case.

[0013] In another aspect of the level sensor inspection device of the present invention, the air ejection portion of the air ejection pipe is provided near the inner peripheral surface of the sensor housing case.

[0014] The lifting unit of the present invention comprises a float-type level sensor that is installed at the top of the liquid storage chamber of a liquid storage tank and closes the bottom valve in the liquid storage chamber when the float rises, and a level sensor inspection device that raises the float by spraying compressed air at the level sensor, wherein the level sensor inspection device comprises an air supply hose that transports compressed air at a pressure higher than atmospheric pressure into the liquid storage chamber, and an air ejection pipe that is connected to the tip of the air supply hose and sprays the compressed air from below the level sensor to the bottom of the level sensor, and wherein the level sensor and the air ejection pipe are formed integrally by a case installed on the ceiling surface of the liquid storage tank. [Effects of the Invention]

[0015] According to the level sensor inspection device of the present invention, a float-type level sensor, which is installed at the top of a liquid storage chamber of a liquid storage tank and closes a bottom valve installed at the bottom of the liquid storage chamber when the float rises, is functioning properly. The level sensor inspection device includes an air supply hose that delivers compressed air at a pressure higher than atmospheric pressure into the liquid storage chamber, and an air outlet pipe connected to the end of the air supply hose that ejects the air from below the level sensor toward the bottom of the level sensor. The float can be raised by ejecting compressed air from the air outlet pipe, so that the level sensor can be checked for proper function without opening the manhole of the liquid storage tank. Furthermore, since the lifting means for lifting and lowering the level sensor uses compressed air, the float of the level sensor can be reliably raised and lowered while liquid fuel is being injected into the liquid storage chamber, thereby reliably inspecting whether the level sensor is functioning properly.

[0016] According to another aspect of the level sensor inspection device of the present invention, a cylindrical sensor housing case is installed between the ceiling and bottom surfaces of the liquid storage chamber, and the level sensor and the air ejection pipe are provided inside the sensor housing case.This allows the compressed air ejected from the air ejection pipe to come into contact with the float without diffusing into the liquid storage chamber, thereby reliably raising the float and reliably inspecting whether the level sensor is functioning normally.

[0017] The lifting unit of the present invention comprises a float-type level sensor that is installed at the top of the liquid storage chamber of the liquid storage tank and closes the bottom valve in the liquid storage chamber when the float rises, and a level sensor inspection device that raises the float by spraying compressed air at the level sensor.The level sensor inspection device comprises an air supply hose that transports compressed air at a pressure higher than atmospheric pressure into the liquid storage chamber, and an air ejection pipe that is connected to the tip of the air supply hose and sprays the compressed air from below the level sensor to the bottom of the level sensor.Since the level sensor and the air ejection pipe are formed integrally in a case installed on the ceiling surface of the liquid storage tank, the level sensor and the air ejection pipe can be easily removed from the liquid storage tank by removing the case, thereby reducing the workload of workers during maintenance. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a side view of an aircraft refueling vehicle equipped with a level sensor according to an embodiment of the present invention. [Figure 2] 1 is a plan view of an aircraft refueling vehicle equipped with a level sensor according to an embodiment of the present invention. [Figure 3] FIG. 2 is a schematic diagram showing the internal structure of a liquid storage chamber according to an embodiment of the present invention. [Figure 4] FIG. 2 is a schematic diagram showing the internal structure of a liquid storage chamber according to an embodiment of the present invention. [Figure 5] 1 is an enlarged cross-sectional side view of a level inspection device according to an embodiment of the present invention. [Figure 6]FIG. 2 is a diagram schematically illustrating a fuel pipe for liquid fuel and an air pipe for compressed air according to an embodiment of the present invention. [Figure 7] FIG. 6 is a cross-sectional view taken along line AA in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention is a lifting unit 7 used to inspect whether or not a level sensor 72 (first level sensor 74 and second level sensor 75) for detecting the liquid level of liquid fuel poured into a liquid storage chamber 43 in a liquid storage tank 4 of an aircraft refueling vehicle V, which is a liquid transport vehicle, is functioning normally, and by devising a means for lifting the level sensor 72 (first level sensor 74 and second level sensor 75), it is possible to reliably lift the level sensor 72 (first level sensor 74 and second level sensor 75) without using liquid fuel or opening the manhole 44 of the liquid storage tank 4. Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] The configuration of the level sensor inspection device 71 according to this embodiment will be described with reference to FIGS. 1 to 7. FIG. 1 is a side view of an aircraft refueling vehicle V equipped with the level sensor inspection device 71, and FIG. 2 is a plan view of the aircraft refueling vehicle V equipped with the level sensor inspection device 71. FIG. 3 is a schematic diagram showing the internal structure of the liquid storage chamber 43. FIG. 4 is a schematic diagram showing the position of the lifting unit 7 of the aircraft refueling vehicle V within the liquid storage chamber 43. FIG. 5 is a diagram illustrating the configuration of the lifting unit 7 within the liquid storage chamber 43 near the level sensor 72. FIG. 6 is a schematic diagram showing the fuel supply piping for liquid fuel supplied from the liquid fuel supply source F and the air piping for compressed air supplied from the air tank T. FIG. 7 is a cross-sectional view taken along line AA in FIG. 5, showing the positional relationship between the sensor housing case 78 and the first and second air ejection pipes 76 and 77. In this embodiment, the liquid transport vehicle will be described using an aircraft refueling vehicle V as an example.

[0021] The aircraft refueling vehicle V has a driving section 2 at the front of a body frame 1, and from the driving section 2 to the rear of the vehicle are a refueling work section 3, a liquid storage tank 4, and a control section 5. Wheels 6 that support the body are attached to the bottom of the body frame 1, which extends in the fore-and-aft direction of the aircraft refueling vehicle V.

[0022] The liquid storage tank 4 has a tank body 41 extending in the front-to-rear direction of the vehicle, four partition walls 42 provided at predetermined intervals within the tank body 41, and five liquid storage chambers 43 formed independently within the tank body 41 by the partition walls 42. The tank body 41 is made of a conductive material.

[0023] 2, a manhole is provided in the ceiling surface 43a, located approximately in the center of each liquid storage chamber 43 in the longitudinal direction and slightly to the right in the lateral direction when the vehicle travel direction is the front, as a hole that connects the inside and outside of each approximately circular liquid storage chamber 43. A removable manhole cover 44a is attached to each manhole. Each manhole cover 44a is equipped with an openable / closable cover 44b, a forced release valve, a safety valve, and a measuring scale.

[0024] A head cover 46 is provided on the ceiling surface 43a of each liquid storage chamber 43, in front of the manhole cover 44a. Below the head cover 46, i.e., inside the liquid storage chamber 43, is a lifting unit 7. The lifting unit 7 comprises a level sensor inspection device 71 and a level sensor 72. The level sensor inspection device 71 has a sensor housing case 78 suspended from the case 47 and air ejection pipes (a first air ejection pipe 76 and a second air ejection pipe 77) housed within the sensor housing case 78. The first air ejection pipe 76 and the second air ejection pipe 77 are connected to the tip of an air supply hose 73, which is located at the rear lower part of the driver's unit 2 and whose base end is connected to an air tank T that controls the aircraft refueling vehicle V. The level sensor 72 comprises a first level sensor 74 and a second level sensor 75. The manhole cover 44a is made of a conductive material.

[0025] As shown in FIG. 6 , a bottom valve 45 is provided on the bottom surface of each liquid storage chamber 43 for supplying or discharging liquid fuel to or from the liquid storage chamber 43. An inlet / outlet pipe P is connected to the bottom valve 45 for transporting liquid fuel from a liquid fuel supply source F to the liquid storage chamber 43 or for discharging liquid fuel from the liquid storage chamber 43. An air supply hose 73, the base end of which is connected to an air tank T, is also connected to the bottom valve 45. The bottom valve 45 is connected to the inlet / outlet pipe P and controls the opening and closing of the valve connected to the inlet / outlet pipe P by compressed air generated in the air tank T. That is, when compressed air is supplied from the air tank T through the air supply hose 73, the bottom valve 45 is opened, allowing the liquid fuel to be supplied to or discharged from the liquid storage chamber 43. When the supply of compressed air from the air tank T is stopped, the bottom valve 45 is closed, restricting the inflow or outflow of liquid fuel into or from the liquid storage chamber 43.

[0026] The inflow / outflow pipe P connected to the bottom valve 45 is connected to an inflow pipe P1 that supplies liquid fuel from a liquid fuel supply source F to each liquid storage chamber 43, a branch pipe P2 that branches off and connects the liquid fuel supplied from the inflow pipe P1 to each liquid storage chamber 43, an outflow branch pipe P3 that is connected to the branch pipe P2 and transports the liquid fuel stored in each liquid storage chamber 43 to the fuel filler port of the aircraft, and a return pipe P4 that draws off the liquid fuel from the aircraft tank.

[0027] The inlet pipe P1 has a base end connected to a liquid fuel supply source F and a tip end connected to an inlet / outlet pipe P. An on-off valve D4 and a drain pipe P7 are provided between the inlet pipe P1 and the inlet / outlet pipe P. The drain pipe P7 is provided between the on-off valve D4 and the liquid fuel supply source F.

[0028] The outflow branch pipe P3 has a base end connected to the inflow / outflow pipe P and a tip connected to a fuel supply pipe P6 that connects to the aircraft's fuel filler port. The outflow branch pipe P3 has a return pipe P4, a first three-way valve D1, and a second three-way valve D2 between the inflow / outflow pipe P and the fuel supply pipe P6.

[0029] The return pipe P4 has its base end connected to the outflow branch pipe P3 and its tip end connected to the first three-way valve D1. The return pipe P4 is provided to extract fuel from the aircraft tank and return the fuel to the reservoir chamber 43. The fuel passes from the aircraft tank through the bypass pipe P5, the second three-way valve D2, the pressure pump PP, the flow meter M, and the first three-way valve D1 in that order, and then passes through the return pipe P4 and the inflow / outflow pipe P and flows into the reservoir chamber 43.

[0030] A bypass pipe P5 is connected to the second three-way valve D2, which is provided midway through the outflow branch pipe P3. The base end of the bypass pipe P5 is connected to the second three-way valve D2, and the tip end is connected to the outflow branch pipe P3 between the first three-way valve D1 and the fuel supply pipe P6. A pressure pump PP and a flow meter M are provided in the outflow branch pipe P3, which is located between the second three-way valve D2 and the first three-way valve D1. In FIG. 6, P7 and P8 are drain pipes for discharging liquid fuel remaining in each pipe or the liquid storage chamber 43 to the outside. D3, D4, D5, and D6 are on-off valves for the liquid fuel flowing through each pipe. D7 and D8 are on-off valves for supplying compressed air generated in the air tank T via an air supply hose 73 to the bottom valve 45 and the forced release valve, or to the first air ejection pipe 76 and the second air ejection pipe 77.

[0031] With the inflow and outflow pipes P configured as described above, by pumping liquid fuel from the liquid fuel supply source F while opening the on-off valve D4 provided midway through the inflow pipe P1, the liquid fuel can be supplied from the inflow pipe P1 through the inflow and outflow pipes P and through the branch pipe P2 to the liquid storage chamber 43. At this time, the bottom valve 45 is opened by opening the on-off valve D7 to supply compressed air from the air tank T, thereby bringing the branch pipe P2 and the liquid storage chamber 43 into communication.

[0032] Then, by closing the on-off valve D4 provided midway through the inlet pipe P1 while opening the on-off valve D6, and then switching the flow path of the first three-way valve D1 and the second three-way valve D2 attached to the outlet branch pipe P3 to a direction that allows fuel to be supplied to the fuel supply pipe P6, and driving the pressure pump PP, the liquid fuel stored in the liquid storage chamber 43 can be supplied to the aircraft from the branch pipe P2 via the outflow branch pipe P3 and the fuel supply pipe P6.

[0033] The opening and closing of the on-off valve D4 and the bottom valve 45 is controlled by a control signal from the control unit 5, and when the level sensor 72 (first level sensor 74 and second level sensor 75) is activated, the bottom valve 45 and the on-off valve D4 are closed via the control unit 5, thereby automatically stopping the supply or discharge of liquid fuel to the storage tank 4.

[0034] For example, when either the first level sensor 74 or the second level sensor 75 in the liquid storage chamber 43 closest to the driving unit 2 is activated, the control unit 5 controls the bottom valve 45 in the liquid storage chamber 43 closest to the driving unit 2 to be closed. Furthermore, when all of the first level sensors 74 in each liquid storage chamber 43 are activated, or when any of the second level sensors 75 provided in each liquid storage chamber 43 is activated, the control unit 5 controls the on-off valve D4 to be closed. This configuration, in which the bottom valve 45 of the liquid storage chamber 43 having the activated level sensor 72 is closed in response to the activation of the level sensor 72, prevents liquid fuel from being poured into the liquid storage chamber 43 in excess of its storable amount. Furthermore, by closing the on-off valve D4 provided in the supply path for liquid fuel supplied from the liquid fuel supply source F in accordance with the above-described conditions, the supply of liquid fuel to the liquid storage tank 4 and the inlet / outlet pipe P can be reliably shut off.

[0035] In addition, a forced release valve is attached to the ceiling surface of the liquid storage chamber 43. The forced release valve is configured to communicate with the outside air so that the pressure inside the liquid storage chamber 43 does not decrease when liquid fuel is discharged from the liquid storage chamber 43 through the branch pipe P2. This makes it possible to prevent deformation or damage to the liquid storage chamber 43. The forced release valve is controlled to open and close in conjunction with the bottom valve 45, so that if any one of the bottom valves 45 provided in each liquid storage chamber 43 is open, the forced release valves of all the liquid storage chambers 43 are opened.

[0036] In the above-described configuration, the gist of the present invention lies in the structure of the lifting unit 7 provided in each liquid storage chamber 43, and the detailed structure of the lifting unit 7 will be described below.

[0037] 3 to 5 and 7, the lifting unit 7 is provided in each liquid storage chamber 43, forward of approximately the center of the vehicle in the longitudinal direction and slightly to the right in the lateral direction relative to the direction of travel of the vehicle. As described above, the lifting unit 7 comprises the level sensor inspection device 71 and the level sensor 72.

[0038] The level sensor inspection device 71 has a sensor accommodating case 78 suspended from a case 47 provided below the head cover 46, an air supply hose 73 that transports compressed air generated in an air tank T into the sensor accommodating case 78, and a first air ejection pipe 76 and a second air ejection pipe 77 that are connected to the tip of the air supply hose 73 and have air ejection sections (first air ejection section 76a, second air ejection section 77a) that eject the compressed air transported by the air supply hose 73 from below to above the level sensor 72.

[0039] The level sensor 72 has a first level sensor 74 and a second level sensor 75 that have a liquid fuel overload prevention function that prevents an excessive amount of liquid fuel from being loaded into the liquid storage chamber 43. The second level sensor 75 is provided above the first level sensor 74 inside the liquid storage chamber 43 of the aircraft refueling vehicle V.

[0040] The head cover 46 protrudes upward from the ceiling surface 43a and has a generally inverted cup-shaped head cover main body 46a that is hollow inside and open at the bottom, and a disk-shaped flange portion 46b that extends radially outward from the lower peripheral edge of the head cover main body 46a. The head cover 46 is fixed by inserting fixing means such as bolts into the flange portion 46b and screwing the tip of the fixing means into a mounting flange portion 43e provided on the ceiling surface 43a. A case 47 is provided below the head cover main body 46a.

[0041] The case 47 is attached to a mounting flange 43e provided on the ceiling surface 43a. Specifically, the case 47 has a hollow cylindrical case body 47a, a flange 47b extending radially outward from the upper peripheral edge of the case body 47a, and a fixing plate 47c provided inside the case body 47a at approximately the center in the up-down direction so as to close the inside of the case body 47a. The case 47 is attached to the mounting flange 43e by fitting the flange 47b into a counterbore in the mounting flange 43e.

[0042] Fixing plate 47c is configured to be provided at a position below mounting flange 43e when case body 47a is attached vertically to mounting flange 43e. Fixing plate 47c has sensor fixing holes 47d and 47e for fixing first level sensor 74 and second level sensor 75, respectively, and pipe insertion holes 47f and 47g for inserting and fixing first air ejection pipe 76 and second air ejection pipe 77, respectively.

[0043] The pipe insertion holes 47f, 47g are located near the center of the fixed plate 47c in a plan view. As shown in Fig. 7, the pipe insertion holes 47f, 47g are located such that a line connecting the centers of the respective insertion holes is oblique to the opening 78a. The first air ejection pipe 76 and the second air ejection pipe 77 are fixed to the pipe insertion holes 47f, 47g, respectively. The distance between the centers of the pipe insertion holes 47f, 47g and the axis C1 of the sensor housing case 78 is substantially constant. In other words, the centers of the pipe insertion holes 47f, 47g are located on a circumference about the axis C1 in a plan view.

[0044] The sensor fixing holes 47d, 47e are located radially outward of the case body 47a relative to the pipe insertion holes 47f, 47g and are provided in the fixing plate 47c near the inner peripheral wall surface of the case body 47a. The centers of the sensor fixing holes 47d, 47e are located on a circumference centered on the axis C1 of the sensor housing case 78. In other words, the centers of the sensor fixing holes 47d, 47e and the centers of the pipe insertion holes 47f, 47g are located on concentric circles centered on the axis C1 of the sensor housing case 78.

[0045] The upper ends of the first level sensor 74 and the second level sensor 75 are connected and fixed to the sensor fixing holes 47d and 47e, respectively.

[0046] In addition, near the lower end of the case body 47a, there is a sensor fixing hole 47h drilled in a direction perpendicular to the axes C2, C3 of the first level sensor 74 and the second level sensor 75, and the fixing plate 47c has an air vent hole 47k that connects the liquid storage chamber 43 and the sensor storage case 78.

[0047] Sensor fixing hole 47h is a hole for inserting a fixing means such as a bolt, and has an internal thread formed on the inner peripheral surface of the hole. By threading a fixing means such as a bolt into sensor fixing hole 47h and pressing the outer peripheral surface of sensor housing case 78 against the inner peripheral surface of case 47 with the tip of the fixing means, sensor housing case 78 can be fixed vertically within liquid storage chamber 43 between bottom cover 43c provided on bottom surface 43b and case 47.

[0048] Additionally, air vent hole 47k is a hole that connects the interior of sensor housing case 78 with liquid storage chamber 43. Sensor housing case 78 is configured with air vent hole 47k provided in case body 47a, so that the pressure near the upper end of sensor housing case 78 does not rise even when liquid fuel is stored in liquid storage chamber 43. In other words, the pressure inside sensor housing case 78 can be made substantially the same as the pressure inside liquid storage chamber 43, and the liquid levels of liquid fuel injected into sensor housing case 78 and liquid storage chamber 43 can be maintained substantially the same.

[0049] 4 and 5, sensor housing case 78 is a hollow cylindrical body. The upper end of sensor housing case 78 is fixed to case 47, and the lower end is fitted and fixed to bottom cover 43c provided on bottom surface 43b of liquid storage chamber 43.

[0050] The bottom cover body 43c is fixed to a receiving boss 43f provided on the bottom surface of the liquid storage chamber 43 by a fixing means such as a bolt, and has a bottomed, cylindrical position control portion 43g consisting of a bottom portion 43g1 and a side portion 43g2, and a storage case receiving portion 43h extending radially from the lower end peripheral portion of the position control portion 43g.

[0051] The bottom portion 43g1 is provided with a plurality of communication holes 43d that allow the internal space of the sensor housing case 78 to communicate with the liquid storage chamber 43. This allows the liquid level in the liquid storage chamber 43 and the liquid level of the liquid fuel that has flowed into the sensor housing case 78 through the communication holes 43d to be the same liquid level. The position restricting portion 43g is hollow and cylindrical. The outer diameter of the side portion 43g2 of the position restricting portion 43g is smaller than the inner diameter of the sensor housing case 78. In other words, by inserting the position restricting portion 43g into the lower end of the sensor housing case 78 and supporting the lower end of the sensor housing case 78 with the housing case receiving portion 43h, the sensor housing case 78 is restricted from swinging within the liquid storage chamber 43.

[0052] The sensor housing case 78 also has an opening 78a near the case 47 for checking the state of the level sensor 72. In this embodiment, the opening 78a is formed in an oval shape with the vertical direction as the longitudinal direction, and is provided on the rear side in the front-to-rear direction of the vehicle. In other words, the sensor housing case 78 has an opening on the manhole side near the upper end, and is configured so that the state of the level sensor 72 can be checked by opening the opening / closing cover 44b. The shape of the opening 78a is not limited to an oval shape, and may be any shape as long as the first level sensor 74 and the second level sensor 75 that make up the level sensor 72 can be checked through a single opening.

[0053] As shown in Fig. 5, the first level sensor 74 is composed of a sensor support 74a hanging down from the case 47 and a sensor main body 74b attached to the lower end of the sensor support 74a. The sensor support 74a is a hollow cylindrical body. The upper end of the sensor support 74a is fixed to the case 47, and the sensor main body 74b is attached to the lower end.

[0054] As shown in the enlarged view within the dashed dotted line S1 in Figure 5, the sensor main body 74b has a stem 74c connected to the lower end of the sensor support body 74a, upper and lower stoppers 74d, 74e provided near the upper and lower ends of the stem 74c, a reed switch 74f provided in the stem 74c between the upper and lower stoppers 74d, 74e, and a float 74g that surrounds the stem 74c between the upper and lower stoppers 74d, 74e and can move up and down along the stem 74c.

[0055] The stem 74c is formed in a hollow cylindrical shape and is connected and fixed to the lower end of the sensor support 74a, which is fixed to the case 47. The stoppers 74d and 74e are disk-shaped enlarged diameter portions that extend radially outward near the upper and lower ends of the stem 74c and are formed as part of the stem 74c. The upper and lower stoppers 74d and 74e define the range of vertical movement of the float 74g.

[0056] Reed switch 74f has ferromagnetic metal rods inside a glass tube. Reed switch 74f controls the ON / OFF state of the switch by the contact and separation of the metal rods inside the glass tube. The glass tube is filled with nitrogen gas to prevent oxidation of the metal rods that function as the switch.

[0057] The float 74g has a float body 74h and a magnet 74k embedded in the float body 74h. The float body 74h is cylindrical in shape with a hole formed vertically through it in approximately the center in a plan view, and the upper and lower end faces are horizontal. A stem 74c is inserted into the hole formed vertically through the float body 74h, and the axis C2 of the float body 74h is aligned with the axis of the stem 74c.

[0058] The first level sensor 74 thus configured controls the ON / OFF state of the reed switch 74f as the float 74g rises and falls along the stem 74c. In other words, when the float 74g rises, the magnet 74k built into the float 74g approaches a ferromagnetic metal rod. The metal rods become magnetized, attracting each other. When the metal rods come into contact, the reed switch 74f turns ON. When the reed switch 74f turns ON, the on-off valve D7, which supplies compressed air from the air tank T to the bottom valve 45, closes, closing the bottom valve 45 and stopping the supply of liquid fuel to the liquid storage chamber 43. Conversely, when the float 74g is supported by the lower stopper 74e, the magnetization of the metal rod inside the reed switch 74f is released, causing the metal rod to move away, turning the reed switch 74f OFF. When the reed switch 74f is in the OFF state, compressed air can be supplied to the bottom valve 45, and in conjunction with other switch operations, the bottom valve 45 can be opened to supply liquid fuel into the liquid storage chamber 43.

[0059] 5 and the enlarged view of the dashed-dotted line S2 in FIG. 5, the second level sensor 75 is located higher than the first level sensor 74 within the liquid storage chamber 43, but its structure is identical to that of the first level sensor 74. Therefore, the reference numeral 74 assigned to the first level sensor 74 will be referred to as the reference numeral 75, and detailed description thereof will be omitted. The second level sensor 75 also has a float 75g formed in a cylindrical shape like the float 74g of the first level sensor 74, and the axis C3 of the float 75g is aligned with the axis of the stem 75c.

[0060] Like the first level sensor 74, the second level sensor 75 controls the ON / OFF state of the reed switch 75f by the rise and fall of the float 75g along the stem 75c. In other words, when the float 75g rises, the magnet 75k built into the float 75g approaches a ferromagnetic metal rod. The metal rods become magnetized, attracting each other. When the metal rods come into contact, the reed switch 75f turns ON. When the reed switch 75f turns ON, the supply of compressed air to the bottom valve 45 is cut off, closing the bottom valve 45 and stopping the injection of liquid fuel into the liquid storage chamber 43. Conversely, when the float 75g is located near the lower stopper 75e, the magnetization of the metal rod inside the reed switch 75f is released, causing the metal rod to move away, turning the reed switch 75f OFF. When the reed switch 75f is in the OFF state, compressed air can be supplied to the bottom valve 45, and in conjunction with other switch operations, the bottom valve 45 can be opened to inject liquid fuel into the liquid storage chamber 43.

[0061] The level sensor 72 (first level sensor 74 and second level sensor 75), the first air ejection pipe 76, and the second air ejection pipe 77 are fixed to the case 47 together with the sensor housing case 78. Therefore, the level sensor 72 is configured so that the first level sensor 74, the second level sensor 75, the first air ejection pipe 76, and the second air ejection pipe 77 can be removed from the liquid storage chamber 43 together with the case 47 by removing the head cover 46 attached to the ceiling surface 43a of the liquid storage chamber 43 from the mounting flange portion 43e and loosening fastening means such as bolts inserted into the sensor fixing holes 47h of the case body 47a to separate the sensor storage case 78 from the case 47 and then lifting the case 47 upward. This configuration, in which the case 47 and the level sensor 72 can be removed together, facilitates maintenance and the like.

[0062] 5, the air supply hose 73 is a hollow, cylindrical pipe whose base end is connected to the air tank T and whose tip end extends to the inside of the case 47 of each liquid storage chamber 43. The air supply hose 73 has a main hose 73a whose base end is connected to the air tank T and which has a pressure gauge and an on-off valve D8 along the way, a third three-way valve D9 connected to the tip end of the main hose 73a for switching the supply destination of the compressed air, and a first hose 73b and a second hose 73c whose base ends are connected to the third three-way valve D9 and whose tip ends are housed inside the case 47.

[0063] The distal ends of the first hose 73b and the second hose 73c are connected to a first air ejection pipe 76 and a second air ejection pipe 77, respectively. The base end of the first air ejection pipe 76 is connected to the distal end of the first hose 73b and hangs down from the distal end of the first hose 73b along the axis C1 of the sensor housing case 78. The distal end of the first air ejection pipe 76 is folded back 180 degrees to form a roughly J-shape in front view, and has a first air ejection portion 76a at its distal end for ejecting high-pressure air. With the distal end of the first air ejection pipe 76 folded back 180 degrees in this manner, compressed air supplied from the air tank T via the air supply hose 73 can be supplied to the lower part of the float 74g. The first air ejection portion 76a is located at a position offset from the axis C2 of the float 74g, i.e., below the lower peripheral edge of the float 74g. In this embodiment, the float 74g is provided near the inner circumferential surface of the sensor housing case 78. As a result, the float 74g of the first level sensor 74 rises along the stem 74c when compressed air is ejected from the first air ejection part 76a through each hose, and descends along the stem 74c when the supply of compressed air is stopped.

[0064] The second air ejection pipe 77 has its base end connected to the tip of the second hose 73c and extends downward from the tip of the second hose 73c along the axis C1 of the sensor housing case 78. The tip of the second air ejection pipe 77 is folded back 180 degrees to form a generally J-shape in front view, and has a first air ejection port 76a at its tip for ejecting high-pressure air. This 180-degree folded tip of the second air ejection pipe 77 allows compressed air supplied from the air tank T via the air supply hose 73 to be supplied to the lower part of the float 75g. The second air ejection port 77a is located at a position offset from the axis C3 of the float 75g, i.e., below the lower periphery of the float 75d. In this embodiment, the second air ejection port 77a is located near the inner circumferential surface of the sensor housing case 78. As a result, the float 75g of the second level sensor 75 rises along the stem 75c when compressed air is ejected from the second air ejection part 77a through each hose, and descends along the stem 75c when the supply of compressed air is stopped.

[0065] 5 and 7, the first air ejection pipe 76 and the second air ejection pipe 77 are inserted into the sensor housing case 78 from pipe insertion holes 47f, 47g provided in approximately the center of the case 47, extend along the axis of the sensor housing case 78 to a position below the sensor main bodies 74b, 75b of the first level sensor 74 and the second level sensor 75, and then bend so that their tips face upward near the inner circumferential surface of the sensor housing case 78. In other words, the tips of the first air ejection pipe 76 and the second air ejection pipe 77 are configured so that compressed air ejected from each pipe is supplied to the lower parts of the sensor main bodies 74b, 75b on the inner circumferential surface side of the sensor housing case 78, as shown in FIG.

[0066] The level sensor inspection device 71 of the present invention is configured as described above and is positioned in front of the manhole cover 44a of each liquid storage chamber 43, and the sensor accommodating case 78 of the level sensor inspection device 71 is connected to the liquid storage chamber 43 by multiple communication holes 43d, so that the liquid level of the liquid fuel in the liquid storage chamber 43 and the liquid level of the liquid fuel in the sensor accommodating case 78 can be maintained on the same horizontal plane.

[0067] Furthermore, since the level sensor 72 (first level sensor 74 and second level sensor 75) and the air ejection pipe (first air ejection pipe 76 and second air ejection pipe 77) are provided inside the sensor housing case 78, even if the vehicle is driven with liquid fuel stored in the liquid storage chamber 43 and the liquid level in the liquid storage chamber 43 fluctuates, the change in the liquid level in the sensor housing case 78 can be kept small, and the load generated by the liquid fuel fluctuating on the first level sensor 74, the second level sensor 75, the first air ejection pipe 76, and the second air ejection pipe 77 can be reduced, thereby minimizing the risk of deformation of each sensor and each pipe.

[0068] In addition, the sensor housing case 78, the case 47 with the upper end of the sensor housing case 78 attached to the ceiling surface 43a of the liquid storage chamber 43, and the bottom cover 43c connected to the lower end of the sensor housing case 78 and attached to the bottom of the liquid storage chamber 43 are all made of a conductive material, just like the tank body 41 and the manhole cover 44a. This makes it possible to remove any bias in the electric charge generated in the liquid fuel in the liquid storage chamber 43 to the outside of the liquid storage tank 4, preventing charging and preventing explosions caused by static electricity.

[0069] Furthermore, since the level sensor inspection device 71 of the present invention has the level sensor 72 and the air supply hose 73 fixed integrally to the case 47, the head cover 46 can be removed from the mounting flange portion 43e and the connection between the sensor storage case 78 and the case 47 by the fixing means screwed into the sensor fixing hole portion 47h of the case 47 can be released, thereby easily removing the device from the ceiling surface 43a of the liquid storage chamber 43, making maintenance easy to perform.

[0070] Furthermore, by providing the first air ejection pipe 76 and the second air ejection pipe 77 inside the sensor housing case 78, the compressed air ejected from each air ejection pipe can come into contact with the float 74g (or the float 75g) without diffusing into the liquid storage chamber 43, thereby reliably lifting the float 74g (or the float 75g). In detail, the compressed air ejected from the first air ejection portion 76a (or the second air ejection portion 77a) of each air ejection pipe is branched into direct air that presses against the float 74g (or the float 75g) after ejection, lifting the float 74g (or the float 75g), and indirect air that rises between the outer circumferential surface of the float 74g (or the float 75g) and the inner circumferential surface of the sensor housing case 78. At this time, the float 74g (or the float 75g) can be reliably raised along the stem 74c (or the stem 75c) due to the interaction between the pressing force of the direct air and the frictional force generated in the float 74g (or the float 75g) as the indirect air passes between the outer surface of the float 74g (or the float 75g) and the inner surface of the sensor housing case 78.

[0071] Furthermore, since it is possible to check whether first level sensor 74 and second level sensor 75 are functioning normally using compressed air generated in air tank T via air supply hose 73, first air ejection pipe 76, and second air ejection pipe 77, it is possible to easily check the operation of level sensor 72 while supplying liquid fuel into liquid storage chamber 43. Furthermore, when checking the operation of level sensor 72, it is possible to check the operation of level sensor 72 without opening opening / closing cover 44b provided on manhole cover 44a on ceiling surface 43a of liquid storage chamber 43, and therefore it is possible to check the operation of level sensor 72 without an operator having to inhale the volatile liquid fuel injected into liquid storage chamber 43.

[0072] It should be noted that the present invention is not limited to the above-described embodiments, but also includes configurations in which the components disclosed in the above-described embodiments are substituted with each other or the combinations are changed, known inventions, and configurations in which the components disclosed in the above-described embodiments are substituted with each other or the combinations are changed, etc. Furthermore, the technical scope of the present invention is not limited to the above-described embodiments, but extends to the matters set forth in the claims and their equivalents. [Explanation of symbols]

[0073] 1 Body frame 2. Driving section 3 Refueling Work Section 4. Storage tank 5. Control section 6 wheels 7 Level sensor inspection equipment 41 Tank body 42 Partition Wall 43 Liquid storage chamber 43a Ceiling surface 43b Bottom 44 Manhole 45 Bottom valve 46 Headcover 71 Sensor storage case 72 Level Sensor 73 Air supply hose 74 First level sensor 74g float 75 Second level sensor 75g float 76 First air jet pipe 76a First air outlet 77 Second air jet pipe 77a Second air outlet T Air Tank PP pressure pump V Aircraft Refueling Truck

Claims

1. A level sensor inspection device is used to inspect whether a float-type level sensor, which is installed at the top of a liquid storage chamber of a liquid storage tank and closes a bottom valve in the liquid storage chamber when the float rises, functions normally. an air supply hose that delivers compressed air at a pressure higher than atmospheric pressure into the liquid storage chamber; an air ejection pipe connected to a tip end of the air supply hose and ejecting the compressed air from below the level sensor to a lower portion of the level sensor; and A level sensor inspection device characterized in that the float can be raised by jetting the compressed air from the air jet pipe onto the float.

2. a cylindrical sensor housing case is installed between the ceiling surface and the bottom surface of the liquid storage chamber; 2. The level sensor inspection device according to claim 1, wherein the level sensor and the air ejection pipe are provided inside the sensor housing case.

3. 3. The level sensor inspection device according to claim 1, wherein the air ejection portion of the air ejection pipe is provided near the inner peripheral surface of the sensor housing case.

4. a float-type level sensor that is provided at the top of the liquid storage chamber of the liquid storage tank and closes a bottom valve in the liquid storage chamber when the float rises; a level sensor inspection device that ejects compressed air onto the level sensor to raise the float; and The level sensor inspection device includes: an air supply hose that delivers compressed air at a pressure higher than atmospheric pressure into the liquid storage chamber; an air ejection pipe connected to a tip end of the air supply hose and ejecting the compressed air from below the level sensor to a lower portion of the level sensor; and a lifting unit in which the level sensor and the air ejection pipe are integrally formed in a case provided on the ceiling surface of the liquid storage tank;

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