Patent Application
20150211446
Embodiments of the invention generally relate to vehicle fuel supply systems including, for example, vehicle fuel supply systems configured to deliver liquefied petroleum gas (LPG) to a combustion engine.
LPG or Autogas is a common low boiling point fuel that includes a combination of propane and butane. It is desirable to use LPG in combustion engines due to its high octane rating and energy content, and low carbon dioxide exhaust emissions.
LPG and other low boiling point fuels must be maintained under pressure at temperatures above their boiling points to maintain the fuels in their liquid state. Examples of low boiling point liquids and fuels are propane (−42F), propylene (−54F), butane (−5F), dimethyl-ether (−5F), and ammonia (−28F).
Autogas tanks for motor vehicles are typically fabricated by welding together steel stampings: the round shell and the end domes. Along with mounting and lifting brackets, fittings for outlet valves, fill valves, and level and pressure sensors are welded to the wall or end domes, as specified by the vehicle manufacturer. The manufacturer is required to pressure test each tank at five times the pressure relief valve setting, which is typically 22 Mpa or 312 psi, or 110 MPa or 1760 psi.
The advent of electronic fuel injection of LPG in the 1990′s brought with it the need to pressurize the fuel system to avoid vaporization prior to injection. However, withdrawing a saturated liquid from a tank with any level of pump suction, even from slightly below the pressure shown in
U.S. Pat. No. 5,291,869, which issued to David Bennett, utilized an in-tank gasoline pump to form a liquid injection propane electronic fuel injection (LPEFI) tank. A schematic diagram of an in-tank LPG fuel injection system is provided in
One technique that has been used to reduce the likelihood of vaporlock, is to place the pump in a short vertical tube that is welded to the bottom of the tank in accordance with gasoline fuel injection practice. This provides the inlet of the pump with a vertical head of fuel due (e.g., 1 inch) to wave action filling the tube. However, in most truck applications, where the bottom of the tank is exposed to the road and associated flying road trash, pump placement to achieve a positive inlet head is especially problematical, as the pump cannot be positioned below the tank.
In-tank fuel injection pumps tend to require frequent servicing due to the propane and the type of pumps that are used. Propane fuel is typically contaminated with particles that resist filtration using the best commercially available autogas filters, which are rated at 3.0 microns and a 99.8% capture rate. These contaminants may adversely affect the operation of in-tank pumps.
Also, most in-tank pumps, both gasoline and propane, have brush-type motors, which are submerged in the fuel. These factors cause in-tank pumps to wear and eventually fail.
When in-tank fuel injection pumps fail, all of the autogas in the tank must be removed before accessing the pump. The removal of the low boiling point fuel involves releasing a significant amount of fuel vapor into the atmosphere, unless an expensive capturing system is used. The process needs to be done outside, away from other vehicles and buildings. Typically 20 to 40 gallons needs to be removed, a process can take over two hours, and it must be watched by the technician. Grounding the tank to avoid static electricity discharge when servicing the open tank is mandatory.
Embodiments of the invention are directed to fuel supply systems for supplying a low boiling point fuel to an internal combustion engine of a vehicle, and methods of supplying a low boiling point fuel to an internal combustion engine of a vehicle using the system. Some embodiments of the system include a fuel tank that encloses a tank volume and includes a primary chamber within the tank volume, a head chamber within the tank volume, and a divider wall. The head chamber is configured to contain fuel up to a head height. The divider wall is attached to a wall of the fuel tank and separates the primary chamber and the head chamber. A fluid pathway guides fuel from along a floor of the tank in the primary chamber through the divider wall and into the head chamber at or above the head height, responsive to movement of the fuel in the primary chamber. An output port is located in a wall of the head chamber adjacent the floor.
In some embodiments of the method, a fuel tank is mounted on a mobile vehicle. The fuel tank encloses a tank volume and includes a primary chamber within the tank volume, a head chamber within the tank volume that is configured to contain fuel up to a head height, and a divider wall that is attached to a wall of the fuel tank and separates the primary chamber and the head chamber. In the method, fuel is guided from along a floor of the tank in the primary chamber and into the head chamber through a fluid pathway responsive to movement of the mobile vehicle. The fuel is pumped from the head chamber through an output port and to the internal combustion engine using a pump that is located externally to the tank volume.
Embodiments of the invention are described more fully hereinafter with reference to the accompanying drawings. Elements that are identified using the same or similar reference characters refer to the same or similar elements. The various embodiments of the invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Specific details are given in the following description to provide a thorough understanding of the embodiments. However, it is understood by those of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, circuits, systems, networks, processes, frames, supports, connectors, motors, processors, and other components may not be shown, or shown in block diagram form in order to not obscure the embodiments in unnecessary detail.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, if an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Thus, a first element could be termed a second element without departing from the teachings of the present invention.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Embodiments of the invention may also be described using flowchart illustrations and block diagrams. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process is terminated when its operations are completed, but could have additional steps not included in a figure or described herein.
It is understood that one or more of the blocks (of the flowcharts and block diagrams) may be implemented by computer program instructions. These program instructions may be provided to a processor circuit, such as a microprocessor, microcontroller or other processor, which executes the instructions to implement the functions specified in the block or blocks through a series of operational steps to be performed by the processor(s) and corresponding hardware components.
In some embodiments, the system 100 includes a fuel tank 106 that encloses a tank volume 108. In some embodiments, the tank 106 has an elongate shape and a longitudinal axis 110, as shown in
In some embodiments, an output port 112 extends through a wall 132 of the fuel tank 106 adjacent a floor 116 of the tank 106. In some embodiments, the output port 112 includes a manual or solenoid actuated shutoff valve (not shown). In some embodiments, the shutoff valve is a conventional valve that includes a built-in excess flow valve per the NFPA 58 requirements. In the event of a major leakage or line failure in the fuel injection system, the excess flow valve will self-close. The excess flow valve is designed to function even when the manual shut off valve is sheared off in an accident.
In some embodiments, the system 100 does not include an electric pump within the tank 106 or tank volume 108. Rather, in some embodiments, the system 100 utilizes an electric pump 120 that is located externally to the tank 106, as shown in
In some embodiments, the system 100 is configured to provide a consistent and deep fluid pressure at an inlet 122 to the external pump 120 to avoid vaporlock in the pump 120. In some embodiments, the tank volume 108 encloses a primary chamber 124 and a head chamber 126, from which the fuel 102 is delivered to the inlet 122. A divider wall 128, located between end walls 130 and 132 of the tank 106, separates the primary chamber 124 from the head chamber 126. In some embodiments, the divider wall 128 is located closer to the end 132 than the end 130 making the primary chamber 124 larger than the head chamber 126. In some embodiments the volume of the head chamber 126 is approximately 5-20% of the volume of the primary chamber 124.
In some embodiments, the divider wall 128 is attached to an interior wall of the tank 106. In some embodiments, a seal is formed between the divider wall 128 and the interior wall of the fuel tank 106 up to at least a head height 136, to which the head chamber 126 can be filled.
The pump 120 draws fuel 102 from within the head chamber 126 through the port 112 and the inlet 122, as indicated in
In some embodiments, fuel 102 that is not delivered for combustion by the fuel injection system is returned to the tank 106, through a return port 144, as shown in
When the engine 104 is fully warmed, some or all of the returning fuel 102 may be vaporous. The vaporized returning fuel 102 increases the pressure in the tank 106 because it cannot be immediately condensed. In some embodiments, an opening 146 is provided between the divider wall 128 and the ceiling of the fuel tank 106, to balance the pressure between the primary chamber 124 and the head chamber 126 and prevent choking of the fluid transfer through the fluid pathway 160 in response to the return of fuel 102 from the fuel injection system. In some embodiments, the opening 146 is formed by deflecting or notching the flange 142 at the twelve o'clock position.
In some embodiments, the system 100 includes a fill port 148, through which fuel may be delivered into the tank 106. In some embodiments, the fill port 148 is configured to discharge fill fuel into the head chamber 126, or the primary chamber 124, as shown in phantom lines. One advantage to configuring the fill port 148 to fill the head chamber 126 is that it allows for a relatively small amount of fuel to be added to the tank 106 to provide a sufficient volume of fuel 102 within the head chamber 126 to allow the engine 104 to operate. When the fill port 148 is located such that fill fuel is discharged into the primary chamber 124, a small bleed hole may be provided in the divider wall 128 slightly below a full level for the primary chamber 124 to ensure that fuel 102 is delivered into the head chamber 126.
In some embodiments, the system 100 includes a stop-fill mechanism or valve 150 that is coupled to the fill port 148 and is configured to prevent overfilling the tank volume 108. In some embodiments, the stop-fill mechanism or valve 150 is configured to limit the filling of the fuel tank 106 to a full level that is above the head height 136. In some embodiments, a filter 152 (e.g., a 3 micron-rated filter) is positioned upstream of the fill port 148 to limit particle introduction into the tank 106.
In some embodiments, the system 100 includes a fluid pathway 160 through which the fuel 102 is transferred from the primary chamber 124 to the head chamber 126 responsive to movement of the fuel 102 within the tank 106. In some embodiments, the tank 106 is mounted to a mobile vehicle 162, as shown in the simplified top view of
In some embodiments, the fluid pathway 160 comprises a tube 164 through which fuel 102 can travel from the primary chamber 124 to the head chamber 126, as shown in
In some embodiments, the tube 164 includes an end 166 that is connected to and/or extends through the divider wall 128 adjacent the floor 116 of the tank 106 (
In some embodiments, the end 166 of the tube 164 includes an opening 170 that may be flared to capture fuel 102 sloshing within the primary chamber 124, as shown in
In some embodiments, the opening 170 of the tube 164 is oriented in the direction of the longitudinal axis 110 of the tank 106, as shown in
In some embodiments, the opening 170 of the tube 164 is oriented in a direction that is perpendicular or transverse to the tank longitudinal axis 110, as shown in
In some embodiments, the tube 164 includes at least one bend 174. In some embodiments, at least one of the bends 174 is oriented in a vertical plane, such as shown in
In some embodiments, the fluid pathway includes a second tube 175 having an end 176 and an end 178. The end 176 of the tube 175 is attached to the divider wall 128 above the end 166 of the tube 164, as shown in
In some embodiments, the fuel guides 182 include an upper guide 182B, which captures the fuel 102 traveling up the divider wall 128 or lower guide 182A, and directs the captured fuel 102 into the head chamber 126, as shown in
In some embodiments, the upper guide 182B is formed by the portion of the divider wall 128 that is cut to form the opening 180. For example, a tab may be cut in the divider wall 128 and bent toward the end wall 130. The tab can then be curved downward to form the upper guide 182B. Alternatively, the upper guide 182B may be a separate component that is attached (e.g., welded, adhered, etc.) to the divider wall 128 adjacent an upper edge of the opening 180.
In some embodiments, a deflector 190 is positioned adjacent the opening 180 on a back side 192 of the divider wall 128 that faces the end wall 132, as best shown in
Additional embodiments of the invention are directed to methods of supplying a low boiling point fuel to an internal combustion engine 104 of a mobile vehicle 162, such as those using embodiments of the system 100 described above. In some embodiments, the fuel supply system 100 in accordance with one or more of the embodiments described herein are mounted to a mobile vehicle 162, as generally illustrated in
In some embodiments of the method, the fluid pathway 160 comprises a tube 164 having a first end 166 connected to the divider wall 128 adjacent the floor 116 and a second end 168 located within the head chamber 126 at or above the head height 136. The fuel 102 in the primary chamber 124 is guided along the floor 116 of the tank 106 in the primary chamber 124 and into the head chamber 126 by delivering fuel 102 along the floor 116 of the primary chamber through the tube 164 and into the head chamber 126 responsive to movement of mobile vehicle 162, as illustrated, for example, in
In some embodiments of the method, the fluid pathway 160 comprises a lower guide 182A extending into the primary chamber 124 from the divider wall 128 toward the floor 116 of the tank 106, and an opening 180 in the divider wall 128 that is at or above the head height 136. The fuel 102 in the primary chamber 124 is guided along the floor 116 of the tank 106 in the primary chamber 124 and into the head chamber 126 by directing the fuel 102 in the primary chamber along the lower guide 182A and into the head chamber 126 through the opening 180 responsive to movement of the fuel in the primary chamber, as illustrated, for example, in
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
| Number | Date | Country | |
|---|---|---|---|
| 61931273 | Jan 2014 | US |
