Fuel tank fluid level sensor

Abstract

A fuel level sensor for a fast refill fuel system is presented having a T shaped valve for positive and negative pressure relief, and a non-spill valve that is overcome when there is a risk of over-pressurization. The level sensor is configured with first and second pilot lines located fully inside the fuel tank to avoid externally pilot lines. The jet level sensor is adjustable to set a height of the sensor corresponding to a selected fuel level.

Description

FUEL TANK FLUID LEVEL SENSORBACKGROUND

[0001] The present invention relates generally to a refueling system for a heavy duty vehicle, and more specifically to a fluid level sensor that cooperates with a fuel supply system to provide rapid refueling of vehicles without over-pressurizing the fuel tank.

[0002] Some heavy duty vehicles have high capacity fuel tanks that can hold up to 1200 gallons or more, and these high capacity tanks utilize rapid fill systems to quickly transfer fuel to fill the large volume of the tanks. Refueling receivers commonly work in conjunction with a fast fill automatic shutoff nozzle that monitors the tank back pressure build up to prevent over-pressurization. In order to use a pressurized refueling system, some fuel tanks have to be structurally designed to withstand internal pressures of up to 10 psi. Such fuel tanks typically are not appropriate for use in lighter vehicles.

[0003] Some high capacity refueling systems involve filling a fuel tank with a release or spill valve that allows excess fuel to spill out of the tank when it is full, indicating to an operator to manually shut off the flow of fuel. However, operators tend to force automatic shutoff nozzles open in order to completely fill pressurized tanks, resulting in frequent fuel spills through the overflow valve or vent. In addition, should a nozzle shutoff valve and a tank overflow valve fail at the same time, excessive pressure in the fuel tank can cause the tank to suffer catastrophic failure.

[0004] For non-pressurized tank refueling, it has been found that a conventional jet level sensor that automatically shuts off flow of fuel through a fuel receiver commonly transmits a significant residual hydraulic signal even when the jet sensor is fully submerged in fuel, such as when the fuel tank is completely full. It is desirable to minimize any residual fluid flow signal when the sensor is fully submerged in order to allow a flow control valve in the fuel receiver to close completely. In addition, non-pressurized refueling systems typically make use of a single signal hose and a hydraulic signal that is controlled by a float valve, so that if the single signal hose is damaged or detached, or if the float valve fails to completely seat, the main fuel flow may not shut off and tank overflow can occur. It is therefore desirable to provide a closed-loop, non-pressurized refueling shut off system such that in the event a signal hose is damaged or detached, the refueling system will fail in a safer condition which results in preventing overfill and over-pressurization of the tank. It is also desirable toprovide a non-pressurized refueling shut off system having a jet sensor with substantially no moving parts, which is less susceptible to wear, and that, even if damaged, would result in an inability to fill the tank, which is a safer condition than if a fuel flow into the tank could not, or would not, be stopped.

[0005] The cost of fuel lost through fuel spills and recent environmental laws make it desirable to avoid fuel spills at refueling stations, so that it would be desirable to provide an automated fuel delivery system for large vehicles which is capable of properly filling fuel tanks and that can avoid the risks of fuel spills and over-pressurization of fuel tanks. The present invention addresses these and other needs.SUMMARY OF THE INVENTION

[0006] The present invention is a fluid level sensor to be used in conjunction with a fuel supply valve to ensure a high fuel transfer rate while protecting against damage to the fuel tank and a failed open condition that could lead to spillage and tank rupture. The sensor of the present invention isolates the fuel lines by locating them inside the fuel tank rather than having them exposed on the tank exterior. The sensor of the present invention exhibits increased resistance to weight and movement of the pilot lines, and is adjustable so that the height of the fuel triggering shutoff is selected by the user. This can be accomplished in various ways, including adding or subtracting cylindrical spacers to position the fuel cut-off height.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is an elevated, perspective view of a prior art fuel tank and sensor arrangement;

[0008] FIG. 2 is a side view diagram of a fuel tank and sensor of the present invention;

[0009] FIG. 3 is an enlarged, perspective cross sectional view of an embodiment of the sensor;

[0010] FIG. 4 is an enlarged, cross sectional view of the embodiment of FIG. 3;

[0011] FIG. 5 is a partial view of the relief valve portion of the sensor under normal filling conditions;

[0012] FIG. 6 is a partial view of the relief valve portion of the sensor approaching max tank capacity condition;

[0013] FIG. 7 is a partial view of the relief valve portion of the sensor in the event the vehicle is rolled over;

[0014] FIG. 8 is a partial view of the relief valve portion in the event of an overpressure condition;

[0015] FIG. 9 is an enlarged cross sectional view of the filter portion of the valve;

[0016] FIG. 10 is an enlarged cross sectional view of the collar and locking rings;

[0017] FIG. 11 illustrates the steps to install the sensor and select the adjustable fluid level height; and

[0018] FIG. 12 shows an alternate version of the fluid level sensor with a splash guard.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Figure 1 illustrates a fuel tank refilling system of the prior art, such as the JN125 system offered by Adel Wiggins Group: https: / / www.transnet.net / DropOffLibrary / Annexure%2014%20Rolling%20Stock%20Specifi cation%20-%20Fuel%20Nozzle.pdf.The tank is supplied with fuel by the nozzle that is connected to a pressurized supply of fuel and introduced into the tank at a fuel receiver disposed on the peripheral wall of the tank. Reference is made to United States Patent No. 9,458,006 for a background and operation of the fuel system, the content of which is fully incorporated herein by reference. Located adjacent the upper surface of the tank is a fuel level sensor which determines when the fuel in the tank is approaching the maximum fill capacity. The sensor is connected to the fuel receiver such that when the sensor determines that the maximum capacity is achieved, a signal from the sensor to the receiver terminates the filling operation and prevents overfilling and / or spillage. The pick-up and return pilot lines are located outside the tank and run along the exterior surface of the tank.

[0020] Figure 2 illustrates a first embodiment of fuel refilling system including a sensor for use with the present invention. A fuel tank 10 is shown in cross section with a fuel levelsensor 12 and a fuel shutoff valve 13. In this figure of a first embodiment of the present invention, that both pilot lines 14, 16 (signal pickup and return) connecting the level sensor 12 and the shutoff valve 13 have been relocated inside the fuel tank 10 and connect to the fuel shutoff valve within the tank’s interior space 15. The positioning of the pilot lines 14, 16 inside the tank 10 eliminates the existence of pressurized fuel lines outside of the tank, providing a system that has an increased fire prevention capability. Moreover, there is less opportunity for the lines to suffer damage, wear, etc. within the protection of the tank, thus providing a more robust refueling system.

[0021] Figure 3 is a cross sectional view of an embodiment of the level sensor 12 of the present invention. The sensor 12 includes a cylindrical valve housing 18 that forms a T valve, with one side 20 leading to a positive pressure relief valve 30 and a second side 22 having a negative pressure relief valve or vent 28. On the positive side 22, a concentric and redundant secondary relief valve 33 may be included to overcome excessive negative pressure in the tank. As fuel enters the tank 10, air escapes past the two buoyant spheres 26 and one non-buoyant sphere 26a, through the cylindrical housing 18, and exits through valve 30. When fuel is consumed during use, the negative pressure / vacuum is relieved by either the negative pressure relief valve 28, which opens in the presence of a negative pressure to allow air to enter the tank, and in cases of excessive negative pressure, through the concentric relief valve 33.

[0022] The valve housing 18 is mounted to a collar 32, which in turn mounts an elongate tubular member 36 from which the sensor detection elements extend. The cylindrical valve housing 18 includes a coil spring 38 that biases a relief plate 40 downward against the collar 32 to seal the juncture of the collar 32 and the valve housing 18. The relief plate 40 includes a central passage 42 having a diameter that is less than the diameter of one or more buoyant spheres 26. The spheres 26 normally sit below the relief plate central passage 42 so that trapped air in the tank 10 can more easily escape the tank through the sensor 12 as the tank fills with fuel, and the air may exit through the designated valve 30.

[0023] Figure 4 is another cross sectional view of the sensor of FIG. 3. The jet sensor body 50 is located at the lowermost end of the elongate tubular member 36 and includes an inlet pilot line (signal pickup) fitting 52 and a pilot return line fitting 54, where the inlet line is typically of a larger diameter than the return line. A fuel channel 56 is formed at the pilot line inlet fitting 52 which is formed with a U-shaped passage and directs a pressurized jet offuel from the inlet pilot line fitting 52 to a fuel jet outlet orifice 58 having a tapered section 60. The tapered section 60 accelerates the fluid while forming a high velocity stream of fuel that shoots across a void and into a fuel jet inlet orifice 62 opposite the void.

[0024] The void exposes the stream of fuel between the fuel jet outlet orifice 58 and the fuel jet inlet orifice 62 to the presence of either air or fuel inside the tank 10, depending upon the fuel level inside the tank. It has been found that when the void is filled with liquid fuel, a significant residual hydraulic signal can still be transmitted across the void in a jet sensor under sufficient hydraulic pressure. To deter this undesirable condition, an intermediary mixing chamber 64 downstream of the fuel outlet orifice 58 advantageously includes a peripheral port 66. The peripheral port 66 is oriented perpendicular to the stream of fuel that shoots across the void. When the jet sensor body 50 is submerged (i.e., fuel has risen to the level of the sensor) and fuel is drawn into the mixing chamber 64 via peripheral port 66 by the Venturi effect, it creates a lateral flow which intersects the stream of fuel moving toward the void. This has the effect of dramatically reducing any residual fluid flow signal when the sensor is fully submerged, allowing the flow control valve in the fuel receiver to close completely.

[0025] When the sensor 12 is not submerged in fuel, the inlet orifice 62 directs the fuel received across the void first into a narrow path 70 that widens at a second tapered section 72, and then the fuel enters a transition section 74 before flowing out through the pilot return line fitting 54. The sensor 12 thus operates to pressurize the flow pilot return line 16 when fuel is below the predetermined level of fuel within the fuel tank, and to not pressurize the pilot return line 16 when fuel is at or above the predetermined level of fuel within the fuel tank 10. Once the fuel level in the fuel tank 10 reaches the void, the stream of fuel from the outlet orifice 58 to the inlet orifice 62 is interrupted and attenuated by the fuel in the tank, thereby stopping the transmission of sufficient velocity head or pressure generated by the jet to the narrow path 70 and transition section 74. There will then be a pressure decrease in pilot return line 16 causing the flow control / shutoff valve 13 to close off the fuel flow into the tank. The interruption of the fuel stream followed by the decrease of pressure in the flow control chamber results in accurate refueling of the tank without under- or over-filling. The void is the detection mechanism in this embodiment, however, other means to interrupt the fuel flow in the fuel channel have been contemplated, and include, but are not limited to, theuse of a flotation device to interrupt the flow through the fuel channel and the use of electrical means to disrupt the fuel flow.

[0026] Figure 5 illustrates the condition of the sensor 12 while the vehicle is operating and during a normal filling operation. The fuel level is not at the level of the sensor and the spheres 26 are away from the relief plate central passage 42. Air can flow freely around the spheres 26 and exit through the relief vent to prevent over-pressurization. The spring 38 continuously pushes down on the relief plate 40 to seal the relief plate against the collar 32 such that the only fluid passage is through the central passage 42 in the relief plate.

[0027] Figure 6 illustrates a condition during refueling whereby the fuel has reached beyond the sensor 12 such that the buoyant spheres 26 have risen up to the point that the top sphere bears against the relief plate central passage 42. No fuel can escape through the relief plate (preventing spillage), as the spring 38 seals the relief plate 40 against the collar 32 and the uppermost sphere seals the central passage 42 in the relief plate 40. If further fueling is experienced, an over-pressurization condition may result.

[0028] Figure 7 illustrates the condition where the vehicle has rolled over and is upside down. Normally this would allow fuel in the tank to pour through the sensor and exit the vehicle, causing a fuel spill and possible fire hazard. To prevent fuel from escaping in this situation, a non-buoyant solid sphere 26a settles against the inverted relief plate 40 to block the central passage 42 and fluidly seal the tank, preventing fuel from spilling out of the tank.

[0029] Figure 8 illustrates the over-pressure condition where the pressure in the tank rises above a determined maximum safe pressure, as might occur during over-filling of the tank. To prevent tank rupture, the internal pressure in the tank 10 overcomes the bias of the spring 38 to move the relief plate 40 off the collar 32 as indicated by arrows 41 and allow air / fuel to bypass the relief plate central passage 42 and exit the relief valve. When the overpressure condition is relieved, the spring 38 will then push the relief plate 40 back against the collar 32 to seal the valve and limit the loss of fuel.

[0030] Figure 9 is an enlarged view of the filter portion of the relief valve 12. As fuel is consumed by the vehicle, a vacuum is formed in the tank that must be relieved to allow a normal flow of fuel. The filter portion introduces air into the tank through an inlet port 90 as the fuel is removed to eliminate a negative pressure in the tank. A coarse mesh filter 92 prevents debris from entering the orifice 90.

[0031] Figure 10 illustrates the collar’s interior, which includes a plurality of cylindrical spacers 80 stacked vertically against the relief plate 40. The spacers 80 can be used to establish a variable height of the level sensor so that the amount of fuel the tank carries can be chosen by the user depending upon the number and height of the spacers.

[0032] Figures 11 A - F illustrate the assembly of the sensor 12 onto the valve body at the collar 32. In Step 1 , over the elongate tubular member 36, a first retaining ring 82 is loosely placed. In Step 2, cylindrical spacers 80 are stacked over the tubular member 36 above the retaining ring 82. A smaller retaining ring 84 is installed into a retaining ring groove 86 over the spacers 80 in Step 3, and in Step 4 the remaining spacers 80 are inserted into the collar 32 below the relief plate 40. In step 5, the elongate tubular member 36 is inserted into the collar 32 such that the smaller retaining ring 84 abuts the lowermost spacer in the collar 32. This sets the height of the fluid level sensor. In Step 6, the larger retainer ring 82 is slid up the elongate tubular member 36 and installed into a retaining ring groove to lock the elongate tubular member 36 into the collar 32 as shown. By adding and subtracting the number of spacers 80 captured on the elongate tubular member, the height of the fluid level sensor can be moved up and down to control the amount of fuel in the tank triggering the shut off. Also, the spacers between the retaining rings act as bushings that allow the pilot lines 14, 16 to swivel without twisting during installation, and permits the device to withstand the forces resulting from the weight and movement of the pilot lines 14, 16. The use of the retaining rings 82, 84 also eliminates the need for adhesive bonding of the tubular member 36 inside the collar 32.

[0033] Figure 12 illustrates an alternate embodiment of the level sensor with a panel 95 surrounding the void of the sensor. The panel 95, which serves as a splash guard, permits fuel to enter the void but prevents fuel that may be sloshing or splashing during the refilling operation from affecting the sensor’s function.

[0034] The benefits of the present invention are important and improve the safety of the system. The fuel level sensor has no moving parts and is less prone to wear and / or breakage. Moreover, the ability to select the height of the fuel level cut-off provides increased flexibility and function to the system. The valve is designed to prevent over-pressurization of the tank even in failure, and the placement of the pressurized fuel lines for the level sensor inside the tank prevents issues relating to failure, spillage, accidental dislodgement, etc. The ability of the cylindrical housing to swivel on the collar allows for the vent to be reorientedafter installation, and the ability of the elongate tubular member to rotate within the collar reduces the opportunity for the internal pilot lines to become twisted and dislodged or damage during installation. The configuration is also more structurally resistant to forces resulting from the weight or movement of the fluid lines.

Claims

We Claim:

1. A fluid level sensor for a vehicle, comprising: a valve housing forming a T section wherein a first side is adapted to impart positive pressure relief and a second side is adapted to impart negative pressure relief; a collar cooperating with the valve housing; a relief plate seated on the collar, the relief plate configured with a central opening; at least one buoyant sphere and one non-buoyant sphere having a diameter larger than a diameter of the central opening; a spring in the valve housing biasing the relief plate against the collar; an elongate tubular member depending from the collar, the elongate tubular member including a first retaining ring for establishing an elevation of the elongate tubular member relative to the collar, and a second retaining ring for affixing the elongate tubular member inside the collar; and a jet level sensor mounted to a lower end of the elongate tubular member, the jet level sensor including a primary pilot inlet fitting and a pilot return outlet fitting.

2. The fluid level sensor of Claim 1, wherein the jet level sensor comprises a U- shaped passage between the primary pilot inlet fitting and the pilot return outlet fitting.

3. The fluid level sensor of Claim 2, further comprising a tapered jet portion opposed a jet inlet orifice separated by a void.

4. The fluid level sensor of Claim 3, wherein the void is enclosed.

5. The fluid level sensor of Claim 3, wherein the void is not enclosed.

6. The fluid level sensor of Claim 3, further comprising an intermediate port between the tapered jet portion and the jet inlet orifice, the intermediate port arranged perpendicular to a direction of flow between the tapered jet portion and the jet inlet orifice.

7. The fluid level sensor of Claim 3, further comprising a plurality of cylindrical spacers within the elongate tubular member.

8. The fluid level sensor of Claim 3, wherein the primary pilot inlet fitting and a pilot return outlet fitting are positioned at a lowermost location of the jet level sensor.

9. The fluid level sensor of Claim 1 , wherein said first side also imparts negative pressure relief through a redundant concentric relief valve.

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