The present invention relates to a high flow pressure relief valve and a process for installing the same, for use in commercial vehicles, for example, and more particularly, to a high flow pressure relief valve that may be installed directly on a fuel tank without additional plumbing positioned between the valve and the tank.
The present invention is particularly intended for use on commercial vehicles, although it may be used with any internal combustion engine connected to a fuel tank. In one particular application, LNG (Liquefied Natural Gas) trucks have one tank for holding natural gas and one smaller tank for holding the diesel used on the LNG truck. LNG engine manufacturers may desire a safety relief valve on the diesel tank to protect the diesel tank if accidental transfer of high pressure from the LNG tank occurs. Such a transfer of high pressure could occur if a pressure seal inside the LNG engine fails. A flow specification of this relief valve might be a flow rate as high as 3,000 standard cubic feet per hour (SCFH) which would prevent rupture of the diesel tank upon occurrence of the accidental transfer of high pressure from the LNG tank. Prior art pressure relief valves are mounted separately from the fuel tank and then plumbed to the fuel tank with hoses and fittings positioned between the valve and the tank. This remote installation of a valve is time intensive and costly and requires more space on the vehicle on which the assembly is installed. There is a need therefore for a safety valve that provides for a high flow rate and which is less time intensive and less expensive to install and which includes a more compact design.
The present invention provides a pressure relief valve and a mating fuel tank bung which are installed directly on a fuel tank, and a process of installing the same. One aspect of the present invention provides a pressure relief valve bung that is welded directly to the tank, and thereafter a pressure relief valve is attached directly to the bung by mating threads. This system and installation method provides a cost savings over prior art devices because the installation process is expedient, no additional plumbing is required, and the resulting installed valve may include additional safety features compared to prior art valves due to the exclusion of additional plumbing positioned between the valve and the fuel tank of the present invention. The present invention is compact and provides for safety release flow rates that meet desired specifications.
The invention discloses a pressure relief valve that is intended for use on commercial vehicles, although it may be used with any internal combustion engine connected to a fuel tank.
In a pressured condition of fuel tank 16, such as at pressures in a range of approximately 6.8 to 8.5 pounds per square inch (psi), as one example, the pressure on slidable shaft 2 may force slidable shaft to begin to move in a direction 34 such that a top portion 36 of slidable shaft 2 is moved away from contact with interior surface 14 of valve body 1, which may allow pressurized air to escape through valve 10 between top portion 36 of slidable shaft 2 and interior surface 14 of valve body 1. At pressures in a range of 10.0 to 15.0 psi, for example, the slidable shaft 2 may be completely clear of interior surface 14 so that the valve 10 may be referred to as completely open, thereby allowing a relatively large flow of pressurized air and/or fluid to escape through valve 10 between top portion 36 of slidable shaft 2 and interior surface 14 of valve body 1, such as allowing a flow rate of 3,000 SCFH, with a maximum back pressure of 13 psi, for example. Such a flow rate of 3,000 SCFH, for example, may prevent rupture of the diesel tank upon pressurization of the fuel tank in the case of an accidental transfer of high pressure from the LNG tank to the fuel tank 16.
In this pressurized condition, as slidable shaft 2 is moved in direction 34, coil spring 4 is compressed thereby drawing baffle 6 and cup washer 7 closer toward valve body 1 in direction 34. Even in a fully pressurized condition wherein coil spring 4 is completely compressed, the spring will normally space baffle 6 a sufficient distance from valve body 1 such that pressured air and/or fluid may still exit the fuel tank 16 through valve body 1 and around top portion 36 of slidable shaft 2.
Pressure relief valve 10 further includes thermal relief ring 5, such as a lead or a silver ring that will deform, such as by melting, for example, at a temperature of approximately 225 degrees Fahrenheit or higher, for example. The deformation of ring 5 may allow bottom portion 38 of slidable shaft 2 to be released from baffle 6 and cup washer 7, thereby allowing shaft 2 to slide freely from valve body 1 and release pressure from fuel tank 16 without compression of coil spring 4. Once slidable shaft 2 is released from baffle 6 and cup washer 7 by activation of thermal relief ring 5, spring 4, baffle 6 and cup washer 7 may no longer be connected to valve body 1 and thereafter spring 4, baffle 6 and cup washer 7 may fall downwardly into an interior the fuel tank 16, further allowing a quick release of pressure through pressure relief valve 10.
In this manner valve body 1 is secured directly on fuel tank 16 such that a portion of coil spring 4 and an entirety of baffle 6 and cup washer 7 are positioned within an interior 44 of fuel tank 16. Moreover, due to this direct installation of pressure relief valve 10 on fuel tank 16, there are no pipes or other plumbing fixtures positioned between valve 10 and fuel tank 16, thereby eliminating safety defects in the present invention that may have been related to such prior art pipes or plumbing fixtures. Moreover, due to this direct installation of pressure relief valve 10 on fuel tank 16, installation costs and component costs are reduced because such prior art pipes and plumbing fixtures need not be purchased or installed in the present inventive installation method. Furthermore, the direct installation process of the present invention results in a more compact size pressure relief valve that requires less space than prior art valves, which included additional pipes and plumbing fixtures.
In this non-roll over position, valve body 1 is positioned vertically above baffle 6 and cup washer 7, as measured in direction 34, such that gravity forces a float 8, such as a float manufactured of a plastic material, and a ball 9, such as a stainless steel ball, downwardly and away from valve body 1 and aperture 46, in downward direction 24. Float 8 includes a seal 10 secured to a side surface 48 of float 8 by a projection 50 and extending over a top surface 52 of float 8. In this non-roll position, seal 10 does not block fluid, air or other gases, from venting through vent aperture 46 in valve body 1 and outwardly to the atmosphere through barb 11.
In a roll over position, such as when a truck and/or a tank to which pressure relief valve 10 is secured, rolls over, such as during an accident, valve body 1 may be positioned other than vertically upright. In particular, in such a roll over position, an axis 54 of relief valve 10 may not be positioned vertically but may be positioned at an angle to vertical, such that baffle 6 and cup washer 7 may be positioned upwardly of or vertically above valve body 1. In such a position, gravity may force float 8 downwardly in a direction 34 such that seal 10 seals against aperture 46, thereby preventing leakage of fuel and/or gases through aperture 46 of relief valve 10, and possibly preventing a fire due to fuel leakage. Float 8 and seal 10 may be held securely against aperture 46 in this position by the downward force of gravity on float 8 and on ball 9, which will force float 8 against aperture 46, wherein ball 9 may be made of a heavily weighted material, such as stainless steel.
Accordingly, there is provided a high flow, pressure relief valve 10 that also allows thermal relief venting during high temperatures in a fuel tank, wherein ring 5 deforms, and also inhibits leakage of fuel during roll-over situations, such that fuel does not leak from a fuel tank during an accident, due to movement of float 8. All of these functions are preformed by compact, sturdy, easily installed relief valve 10.
In the above description numerous details have been set forth in order to provide a more through understanding of the present invention. It will be obvious, however, to one skilled in the art that the present invention may be practiced using other equivalent designs.
This application claims priority on U.S. provisional patent application Ser. No. 61/756,766, filed on Jan. 25, 2013, and claims priority on U.S. provisional patent application Ser. No. 61/734,765, filed on Dec. 7, 2012, both entitled PRESSURE RELIEF VALVE.
Number | Date | Country | |
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61756766 | Jan 2013 | US | |
61734765 | Dec 2012 | US |