Patent Application
20090301583
The present disclosure relates generally to small engine fuel systems.
Small engine fuel systems are often used in many, gas-powered devices such as, for example, power generating sets, garden tractors, lawn mowers, weed cutters, motorcycles, all-terrain vehicles, boats, small recreational transportation vehicles, and/or the like. The small engine fuel system may include a tank having a refilling inlet with a removable filler cap. These small engine fuel systems may be refilled by removing the filler cap and pouring fluid (e.g., fuel) from a portable fluid container. The fluid may be poured through a spout formed on the portable fluid container, or may be poured into the refilling inlet via a funnel. The fluid may also be transferred by a pump from a large tank to the small engine fuel system through a pipe via a nozzle.
Recently, fuel vapor emission requirements have been mandated on many fuel systems, including small engine fuel systems. These fuel vapor emission requirements generally regulate the amount of fuel vapors that may be emitted into the atmosphere when the fuel system is operating or when the fuel system is at rest. In some instances, fuel vapors may also be emitted into the atmosphere when the engine is not running such as, for example, during a refilling event.
A small engine fuel system includes a tank with at least a portion of a filler pipe defined in the tank. The filler pipe includes an upper portion configured to receive a fluid and a lower portion located at a predetermined depth in the tank, where the predetermined depth defines a liquid fill level of the tank. The small engine fuel system further includes a vent valve disposed within the tank and a spring valve arranged in series with the vent valve. The spring valve is configured to close during a refilling event, thereby substantially preventing overfill of the tank with the fluid.
Features and advantages of embodiment(s) of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to the same or similar, though perhaps not identical components. For the sake of brevity, reference numerals having a previously described function may or may not be described in connection with other drawings in which they appear.
Embodiment(s) of the small engine fuel system as disclosed herein advantageously substantially prevent overfilling of a small engine fuel system tank with fluid during a refilling event. This may be accomplished by providing a spring valve in the system such that the spring valve is operatively arranged in series with a vent valve. The spring valve includes low-flow and high-flow fluid passages that close during the refilling event to substantially prevent the escape of vapors from inside the tank through the spring valve. It is to be understood that vapors inside the tank substantially cannot be displaced by rising liquid within the tank after the lower end of the filler pipe is covered by liquid, as such, additional refilling fluid cannot be added to the tank and, thus the tank cannot be overfilled. Prevention of overfilling of the tank may advantageously improve the operating performance of the small engine fuel system. For example, a vapor space is maintained to allow proper venting of a sealed fuel tank (where a refueling cap has been replaced) during engine running or rest conditions.
With reference to
The tank 12 may be a single-layered polymeric structure, a multi-layered polymeric structure, a steel structure, and/or other structures suitable for use in small engine fuel systems. A filler pipe 14 is at least partially disposed in the tank 12 via an opening 16 formed therein. The filler pipe 14 includes an upper portion 18 that is configured to receive the fluid during a refilling event, and further includes a lower portion 20 that extends into the tank 12 at a predetermined depth. The predetermined depth may be selected, at least in part, based on a desired depth of the liquid portion of the fluid to be retained in the tank 12, thereby defining a liquid fill level L of the tank 12. In a non-limiting example, the liquid portion of the fluid may fill the tank 12 up to the liquid fill level L during a refilling event, whereas the vapor portion of the fluid (if any) enters an ullage space that is defined by any space in the tank 12 not occupied by liquid or tank components.
The small engine fuel system 10 further includes a vent valve 22 disposed therein, where the vent valve 22 is in fluid communication with the tank 12. In an embodiment, the vent valve 22 is a rollover vapor vent valve. It is to be understood, however, that any valve capable of venting vapor in a fuel system may also suitably be used as the vent valve 22. The vent valve 22 substantially regulates the flow of any vapors from the tank 12 to, for example, a vapor retention device 54 (schematically shown in
In an embodiment, the vent valve 22 includes at least one flow passage (not shown), where the flow passage(s) remain open during operation of the small engine fuel system 10, during refilling of the tank 12, and/or combinations thereof. Meanwhile, the liquid portion of the fluid remains at or below the liquid fill level L. It is to be understood that as long as the liquid portion of the fluid does not contact the vent valve 22, the fluid passage(s) of the vent valve 22 will remain open. Thus, the fluid passage(s) are open during substantially normal operating conditions of the fuel system 10 (i.e., during substantially normal and conventional use, during an idle state, or when the system 10 is turned off). When the flow passage(s) are open, the vapors in the ullage space of the tank 12 may flow through the flow passage(s) of the vent valve 22 and to a component exterior to the tank 12, such as, for example, the vapor retention device 54.
In some instances, the small engine fuel system 10 may be operated under substantially rough operating conditions (e.g., when operating through rough terrain, when operating on a steep hill, when the system 10 is tipped beyond a predetermined angle, and/or the like). Such conditions may cause the liquid portion of the fluid in the tank 12 to splash or otherwise slosh within the tank 12. Under these conditions, the liquid level inside the tank 12 may rise above the liquid fill level L and contact the vapor vent valve 22. In these situations, the flow passage(s) of the vent valve 22 close, thereby substantially preventing any liquid or vapor from flowing through the vent valve 22. Furthermore, the closed fluid passage(s) substantially prevents any possible contamination of the vapor retention device 54 by the liquid fluid.
The small engine fuel system 10 also includes a spring valve 26 arranged in series with the vent valve 22 and in fluid communication therewith. The spring valve 26 regulates the flow of the fluid to and from the vent valve 22.
With reference now to
A low-flow fluid passage 32 is formed in the piston 28, and includes a valve seat 40 and a movable valve member 42 disposed therein. The movable valve member 42 is positioned adjacent to the valve seat 40. In a non-limiting example, the movable valve member 42 is a relatively light-weight spherical member or ball that is configured to sit or otherwise be positioned against the valve seat 40 in response to a pressure difference across the spring valve 26 (which will be described further below). The movable valve member 42 is also diametrically large enough to block the low-flow fluid passage 32 when the movable valve member 42 is seated against the valve seat 40. When the movable valve member 42 blocks the low-flow fluid passage 32, the low-flow fluid passage 32 is substantially sealed.
The spring valve 26 also includes a high-flow fluid passage 34 that is defined by a space formed between an outer surface 36 of the piston 28 and an inner surface 38 of the cartridge 30. The high-flow fluid passage 34 may be closed by movement of the piston 28 inside the cartridge 30. The piston 28 is generally moved in response to the movement of a spring 44 disposed in the cartridge 30 and positioned adjacent to the piston 28. The spring 44 moves the piston 28 so that the piston 28 contacts the cartridge 30 and substantially seals the high-flow fluid passage 34. In an embodiment, the spring 44 is configured to bias the piston 28 so that the piston 28 contacts the cartridge 30 to close and seal the high-flow fluid passage 34 up to a threshold pressure. In a non-limiting example, the threshold pressure is determined by preloading the spring 44 with a force substantially equal to a predetermined threshold pressure multiplied by an effective area of the piston 28. It is to be understood that the effective area of the piston 28 is the area acted upon by the pressure.
The spring valve 26 is connected to the vent valve 22 via a first port 46, which may generally be fluid-tight. The first port 46 allows fluid communication between the vent valve 22 and the high-flow and low-flow fluid passages 32, 34. The spring valve 26 also includes a second port 48 for generally fluid tight connection with the vapor retention device 54 (shown in
Also disclosed herein is a method of preventing overfilling of the fluid tank 12 for the small engine fuel system 10. The method includes providing the small engine fuel system 10, and substantially sealing the low-flow and the high-flow fluid passages 34, 36 of the spring valve 26 when the pressure of the fluid at the first port 46 is higher than the substantially atmospheric pressure at the second port 48 by a pressure difference that is less than or equal to the threshold pressure, thereby substantially preventing overfilling of the tank 12 during the refilling event.
In an embodiment, the refilling event may include a free fill, where the rate of refilling is not restricted by the small engine fuel system 10. In a non-limiting example, the rate of free filling ranges from about 1 gpm to about 20 gpm. In another embodiment, the refilling event may include a trickle fill, where the refilling rate is substantially slower than the rate for the free fill. In a non-limiting example, the rate of trickle filling ranges from about 0.25 gpm to about 1 gpm. It is to be understood that the fuel system 10 may be configured for free filling of the fluid, trickle filling of the fluid, and/or combinations thereof.
It is also to be understood that prior to filling the tank 12 with fluid, the inside of the tank 12 may already be occupied by a liquid form of the fluid, a vapor form of the fluid, and/or other vapors. During a refilling event, the liquid fluid fills any space defined in the tank 12 located below the liquid fill level L, and any vapors inside the tank 12 occupy the ullage space defined in the tank 12. As more fluid is added to the tank 12 during the refilling event, the amount of the liquid inside of the tank 12 increases and displaces the vapors, if any, occupying the tank 12. Once the level of the liquid fluid reaches the liquid fill level L, additional fluid introduced inside the tank 12 through the filler pipe 14 may well up in the filler pipe 14 and may potentially spill out of the upper portion 18 of the filler pipe 14 if the filler pipe 14 is overfilled.
It is to be further understood that the vapors occupying the tank 12 may be vapors present in the tank 12 prior to refilling, or may be vapors mixed with or generated by the refilling fluid entering the tank 12. In some instances, the vapors may flow out of the tank 12 through the filler pipe 14 until the level of the liquid fluid present in the tank 12 reaches the liquid fill level L. Once the liquid fluid reaches the liquid fill level L, the lower portion 20 of the filler pipe 14 is covered by liquid and substantially prevents the flow of the vapors out of the tank 12 through the filler pipe 14. It is to be understood that after the lower portion 20 of the filler pipe 14 is covered by liquid, a vapor pressure in the ullage may be balanced by a pressure of a column of liquid in the filler pipe 14. An increase in a height of the column of liquid above the liquid fill level L may be a signal to the operator that the tank is full.
It is yet also to be understood that the term “connect/connected” and/or the like are broadly defined herein to encompass a variety of divergent connection arrangements and assembly techniques. These arrangements and techniques include, but are not limited to (1) the direct connection between one component and another component with no intervening components therebetween; and (2) the connection of one component and another component with one or more components therebetween, provided that the one component being “connect to”, the other component is somehow operatively connected to the other component (notwithstanding the presence of one or more additional components therebetween).
While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified and/or other embodiments may be possible. Therefore, the foregoing description is to be considered exemplary rather than limiting.
