Patent Application
20140026869
Fuel stored in a fuel tank and fuel delivery system may be exposed to high temperatures during engine operation. As a result, the temperature of the fuel in the fuel delivery system, and in particular the fuel tank, may exceed a threshold temperature. The excessive temperature condition may degrade the fuel tank and other components (e.g., a fuel pump) in the fuel delivery system. Furthermore, the over-temperature fuel delivered to the engine by the fuel system to downstream components may also reach undesirable temperatures, which may decrease combustion efficiency.
Attempts have been made to reduce the temperature of the fuel delivery system via the engine cooling system. For example, coolant may be redirected from an engine cooling circuit to various portion of the fuel delivery system to provide cooling. However, certain components in the fuel delivery system may require a greater level of cooling than the engine cooling circuit can provide. For example, the temperature of the coolant in some engine cooling circuits may not fall below 100° C. However, the desired temperature of certain components in the fuel delivery system, the fuel in the fuel delivery system, etc., may be below 70° C.
Other attempts have been made to reduce the temperature of the fuel delivery system via an air cooler. The air cooler may be packaged in the front of vehicle or in an area where there is a desired amount of air flow. However, damage to the air cooler from a collision is a concern in these locations.
Attempts have also been made to further reduce the temperature of various components in the fuel delivery system, such as a fuel injector, by other heat transfer mechanisms. U.S. Pat. No. 3,945,353 discloses a fuel injection nozzle having a heat pipe coupled thereto. The heat pipe removes heat from the nozzle and therefore reduces the temperature of the fuel traveling through the nozzle. In this way, fuel traveling through the injector may be cooled.
However, the Inventors have also recognized several drawbacks with the system disclosed in U.S. Pat. No. 3,945,353. To achieve a desired amount of cooling, the condenser of the heat pipe may need to be positioned in a section of the engine or vehicle having a low temperature. However, these low temperature regions may not be close to the fuel injector. Therefore, to reach the low temperature region, the length of the heat pipe is increased. Lengthening the heat pipe may have deleterious effects on the heat pipe's functionality and efficiency, as well as increase the cost of the heat pipe. Moreover, the fuel upstream of the fuel injector may reach undesirable temperatures. This may be particularly problematic in plastic fuel tanks which are more susceptible to thermal degradation than metal fuel tanks. The thermal loading may be exacerbated during periods of engine operation when the ambient temperature surrounding the engine is high. Furthermore, packaging constraints in the fuel injector may limit the size of the heat pipe, thereby limiting the amount of heat that may be removed by the heat pipe.
As such, in one approach a fuel delivery system is provided. The fuel delivery system includes a fuel tank storing a liquid fuel, a return fuel line including an outlet opening into the fuel tank, and a heat pipe assembly including a first end positioned in a surrounding atmosphere, and a second end positioned at and coupled to the return fuel line. In some examples, the heat pipe assembly and specifically the first end may be positioned external (e.g., below) the vehicle frame. In this way, the airflow around the first end may be increased during vehicle travel thereby increasing the cooling provided to the return fuel line.
The heat pipe may be positioned in a more protected zone in the vehicle, for example spaced away from the vehicle body with one or more crush zones between the body and the heat pipe. Such a position may be less susceptible to damage during a collision than the front end of the vehicle, thereby reducing the likelihood of heat pipe damage. Furthermore, the heat pipe and specifically the condenser may also be positioned in a location in the vehicle with a desired amount of airflow, increasing the amount of heat that may be removed from the return fuel line via the heat pipe. Further in some examples, the working fluid of the heat pipe may be water, which may provide desired heat transfer characteristics for petroleum fuel.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
A fuel delivery system is provided herein. The fuel delivery system may include a fuel tank storing a liquid fuel, a return fuel line including an outlet opening into the fuel tank, and a heat pipe assembly including a condenser section dissipating heat from a condenser end of a sealed pipe to the surrounding environment and an evaporator section receiving heat from the return fuel line and transferring heat to an evaporator end of the fluidly sealed pipe.
In this way, the heat pipe assembly may be used to passively remove heat from the return fuel line, thereby reducing the temperature of the fuel returned to the fuel tank. As a result, the temperature of the fuel tank may be reduced to a desirable level. Moreover, lower cost materials may be used to construct the fuel tank, such as plastic if desired, when the temperature of the fuel is reduced.
Referring to
Fuel injector 66 is shown positioned to inject fuel directly into cylinder 30, which is known to those skilled in the art as direct injection. Additionally or alternatively, fuel may be injected to an intake port, which is known to those skilled in the art as port injection. Fuel injector 66 delivers liquid fuel in proportion to the pulse width of signal FPW from controller 12. Fuel is delivered to fuel injector 66 by a fuel delivery including a fuel tank, fuel pump, and fuel rail (not shown). Fuel injector 66 is supplied operating current from driver 68 which responds to controller 12. In addition, intake manifold 44 is shown communicating with optional electronic throttle 62 which adjusts a position of throttle plate 64 to control air flow from intake boost chamber 46. In other examples, the engine 10 may include a turbocharger having a compressor positioned in the induction system and a turbine positioned in the exhaust system. The turbine may be coupled to the compressor via a shaft. A high pressure, dual stage, fuel delivery system may be used to generate higher fuel pressures at injectors 66.
Distributorless ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12. However, in other examples the ignition system 88 may not be included in the engine 10 and compression ignition may be utilized. Universal Exhaust Gas Oxygen (UEGO) sensor 126 is shown coupled to exhaust manifold 48 upstream of catalytic converter 70. Alternatively, a two-state exhaust gas oxygen sensor may be substituted for UEGO sensor 126.
Converter 70 can include multiple catalyst bricks, in one example. In another example, multiple emission control devices, each with multiple bricks, can be used. Converter 70 can be a three-way type catalyst in one example.
Controller 12 is shown in
In some examples, the engine may be coupled to an electric motor/battery system in a hybrid vehicle. The hybrid vehicle may have a parallel configuration, series configuration, or variation or combinations thereof. Further, in some examples, other engine configurations may be employed, for example a diesel engine.
During operation, each cylinder within engine 10 typically undergoes a four stroke cycle: the cycle includes the intake stroke, compression stroke, expansion stroke, and exhaust stroke. During the intake stroke, generally, the exhaust valve 54 closes and intake valve 52 opens. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder so as to increase the volume within combustion chamber 30. The position at which piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g. when combustion chamber 30 is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC). During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head so as to compress the air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g. when combustion chamber 30 is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition means such as spark plug 92, resulting in combustion. Additionally or alternatively compression may be used to ignite the air/fuel mixture. During the expansion stroke, the expanding gases push piston 36 back to BDC. Crankshaft 40 converts piston movement into a rotational torque of the rotary shaft. Finally, during the exhaust stroke, the exhaust valve 54 opens to release the combusted air-fuel mixture to exhaust manifold 48 and the piston returns to TDC. Note that the above is described merely as an example, and that intake and exhaust valve opening and/or closing timings may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples.
The fuel delivery system 202 further includes a pump 206 having a pick-up tube 208 including an inlet 210 positioned in the fuel tank 204. The pump 206 is positioned external to the fuel tank 204, in the depicted embodiment. However, other pump locations have been contemplated.
The fuel delivery system 202 further includes a supply fuel line 212 in fluidic communication with an outlet 214 of the pump 206 and various components in the engine 10. For example, the supply fuel line 212 may be configured to provide fuel to a fuel rail and fuel injectors (e.g., port and/or direct injectors). Arrow 224 denotes the flow of fuel from the pump 206 to the engine 10.
A return fuel line 216 is also included in the fuel delivery system 202. The return fuel line 216 includes an inlet 218 in fluidic communication with the supply fuel line 212 and an outlet 220 in fluidic communication with the fuel tank 204. Thus, the return fuel line 216 extends into the fuel tanks and the outlet 220 is enclosed by the housing of the fuel tank 204. Arrow 226 denotes the general direction of fuel flow through the return fuel line 212. A valve 222 may be positioned in the return fuel line 216. The valve 222 may be configured to allow fuel to pass therethrough when the fuel pressure in the return fuel line 216 is above a predetermined pressure. In this way, the fuel pressure of the fuel in the fuel delivery system 202 may be regulated. The valve 222 may be a passively operation valve such as a check valve or an actively controlled valve such as a solenoid valve controllable via controller 12, shown in
It will be appreciated that the fuel delivery system 202 may include additional components that are not depicted, if desired. For example, a number of valves for regulating the fuel pressure may be included in the fuel delivery system. Moreover, a second pump may also be included in the fuel delivery system 202.
A heat pipe assembly 230 is also shown in
A fuel passage denoted generically, via box 242, is in fluidic communication with the fuel inlet 234 and the fuel outlet 236. The fuel passage 242 flows fuel around at least one fluidly sealed pipe 244. Thus, the fuel passage 242 may at least partially surround a portion of the fluidly sealed pipe 244. The fluidly sealed pipe may be referred to as a fluidly sealed heat pipe or a heat pipe. In this way, heat may be transferred from the fuel to the fluidly sealed pipe 244. Additionally, the fluidly sealed pipe 244 includes an evaporator end, discussed in greater detail herein, at least partially enclosed by the fuel passage 242.
The heat pipe assembly 230 also includes a condenser section 246. The condenser section 246 is configured transfer heat from the heat pipe assembly to the surrounding environment. The condenser section 246 is spaced away from the evaporator section 232. The condenser section 246 is included in a first end 280 of the heat pipe assembly 230. Likewise, the evaporator section 232 is included in a second end 282 of the heat pipe assembly 230. The first end 280 may be positioned in a surrounding atmosphere. In this way, heat may be transferred from the end to the surrounding environment. The second end 282 is positioned at and coupled to the return fuel line 216. The fluidly sealed pipe 244 extends between the condenser section 246 and the evaporator section 232. Specifically, the fluidly sealed pipe 244 further includes an intermediary section 248. The intermediary section 248 extends between the evaporator section 232 of the heat pipe assembly 230 and a condenser section 246 of the heat pipe assembly.
The condenser section 246 and the evaporator section 232 are shown in
Continuing with
Moreover, the heat pipe assembly 230, and specifically the condenser section 246, is positioned below the vehicle frame 303 and the leaf spring 302. In some examples, the heat pipe and specifically the condenser section may be positioned above the vehicle ground line. A vertical axis 400 is provided for reference. It will be appreciated that the heat pipe assembly 230 may receive a greater amount of airflow during vehicle travel when positioned below the vehicle frame. As a result, the amount of heat removed from the fuel via the heat pipe assembly 230 may be increased when compared to heat pipes that are positioned vertically above the vehicle frame. Additionally, the evaporator section 232 is positioned adjacent to a fuel filter 402.
The evaporator section 232 includes an evaporator housing 502. The evaporator housing 502 may define the boundary of the fuel passage 242, shown in
The condenser section 246 includes a condenser casing 504. The condenser casing may include material extending between and surrounding at least a portion of the plurality of fluidly sealed pipes 304. Specifically, in the depicted example the condenser casing 504 is in direct contact with the plurality of fluidly sealed pipes 304. However, other condenser casing configurations have been contemplated. Heat fins may be coupled to the condenser casing 504 and/or the evaporator housing 502 to increase the heat removed from the heat pipe assembly 230. The heat fins may comprise metal such as aluminum. Additionally, the evaporator section 232 and/or the condenser section 246 may comprise plastic and/or a metal such as copper, aluminum, and/or steel (e.g., stainless steel). Furthermore, the fluidly sealed pipes 304 have cross-sections forming a grid pattern.
Additionally, the wicking material 702 encloses a vapor cavity 704. The vapor cavity 704 extends down the fluidly sealed pipe 244 enabling vapor to flow from one section of the fluidly sealed pipe to another. Vapor may flow through the vapor cavity from the evaporator end to the condenser end.
The fluidly sealed pipe 244 includes an evaporator end 710 and a condenser end 712. The evaporator end 710 is partially enclosed via the evaporator housing 502. The condenser end 712 is partially enclosed via the condenser casing. Therefore, the fluidly sealed pipe 244 extends into the evaporator section 232 and into the condenser section 246.
The evaporator section 232 includes the evaporator housing 502 defining the boundary of fuel passage 242. The fuel passage 242 partially surrounds the evaporator end 710. The fuel inlet 234 and the fuel outlet 236 of the fuel passage 242 are also shown. In this way, fuel may be flowed around the fluidly sealed pipe 244. As previously discussed the fuel inlet 234 and the fuel outlet 236 are in fluidic communication with the return fuel line 216. Furthermore, the working fluid in the fluidly sealed pipe may include at least one of water, alcohol, and sodium. In some embodiment, the working fluid may include just water. Water may provide the desired heat transfer properties for cooling of petroleum fuel.
At 802 the method includes, transferring heat to an evaporator section in a heat pipe assembly from a return fuel line having an outlet positioned in a fuel tank of a fuel delivery system, the heat pipe assembly including a fluidly sealed pipe having an evaporator end included in the evaporator section. At 804 the method includes flowing vapor through a vapor cavity of the fluidly sealed pipe, the vapor cavity extending from the evaporator end to a condenser end of the fluidly sealed pipe, the condenser end included in a condenser section of the heat pipe assembly. At 806 the method includes transferring heat from the condenser section to the surrounding environment, the condenser section positioned below a vehicle frame. At 808 the method includes flowing liquid condensed in the condenser end through a wicking material in the fluidly sealed pipe to the evaporator end. Therefore, when a wicking material is used in the heat pipe the evaporator end may be positioned vertically above the condenser end. However, in other embodiments, the wicking material may be omitted from the heat pipe and the condenser end may be positioned vertically above the evaporator end. Therefore, the method may include flowing condensed fluid from the condenser end to the evaporator end via gravity at 808, in some embodiments. In this way, heat may be removed from the return fuel line via a passively operated heat pipe assembly. After 808 the method returns to 802 or ends in other embodiments. Additionally, the heat pipe may not be coupled to a controller. In this way, the heat pipe can be passively operated without the use of a controller, if desired. Method 800 may be implemented during engine operation when fuel is flowing through the return fuel line.
This concludes the description. The reading of it by those skilled in the art would bring to mind many alterations and modifications without departing from the spirit and the scope of the description. For example, single cylinder, inline engines, V-engines, and horizontally opposed engines operating in natural gas, gasoline, diesel, or alternative fuel configurations could use the present description to advantage.
