Fuel cooling system

A fuel system includes a cooling fuel supply line that conveys a flow of cooling fuel from a storage tank to a mixing device. An upstream fuel return line conveys a flow of heated fuel to the mixing device from an internal combustion engine. The flow of the heated fuel from the upstream fuel return line mixes with the flow of cooling fuel from the cooling fuel supply line in the mixing device to form a flow of mixed fuel. A downstream fuel return line conveys the flow of mixed fuel from the mixing device to the storage tank. The mixing device includes a flow restrictor operable to generate a low pressure zone relative to a fluid pressure of the flow of cooling fuel in the cooling fuel return line that draws the flow of the cooling fuel through the cooling fuel supply line and into the mixing device.

TECHNICAL FIELD

The disclosure relates to a fuel cooling system for a vehicle having a diesel engine.

BACKGROUND

Modern diesel engines include fuel systems that use a high pressure fuel pump to supply fuel to the fuel injectors. Fuel that is not used by the fuel injectors is circulated back to the fuel storage tank. Under some operating conditions, the fuel that is not used for combustion by the fuel injectors and is circulated back to the fuel storage tank may become heated during the circulation process. It is desirable to maintain the temperature of the fuel being circulated back to the fuel storage tank below a predetermined temperature. Accordingly, some vehicles are equipped with a cooling system for cooling the fuel being circulated back to the fuel storage tank.

SUMMARY

A fuel system is provided. The fuel system includes a storage tank, and a mixing device. A cooling fuel supply line is disposed in fluid communication with the mixing device and the storage tank. The cooling fuel supply line conveys a flow of cooling fuel from the storage tank to the mixing device. An upstream fuel return line is disposed in fluid communication with the mixing device. The upstream fuel return line conveys a flow of heated fuel to the mixing device. The flow of the heated fuel from the upstream fuel return line mixes with the flow of cooling fuel from the cooling fuel supply line in the mixing device to form a flow of mixed fuel. A downstream fuel return line is disposed in fluid communication with the mixing device and the storage tank. The downstream fuel return line conveys the flow of mixed fuel from the mixing device to the storage tank. The mixing device includes a lifting injector that is operable to generate a low pressure zone within the mixing device that draws the flow of the cooling fuel through the cooling fuel supply line and into the mixing device.

A vehicle is also provided. The vehicle includes a diesel engine having a high pressure fuel pump, and a plurality of fuel injectors. A high pressure fuel line interconnects the high pressure fuel pump and the plurality of fuel injectors. The vehicle further includes a fuel storage tank for storing fuel. A fuel feed line is disposed in fluid communication with the fuel storage tank and the high pressure fuel pump. The fuel feed line supplies fuel from the storage tank to the high pressure fuel pump. An upstream fuel return line is disposed in fluid communication with the high pressure fuel line. The upstream fuel return line receives heated fuel from the high pressure fuel line. A downstream fuel return line is disposed in fluid communication with the upstream fuel return line and the storage tank. The downstream fuel return line conveys fuel back to the storage tank. A mixing device interconnects the upstream fuel return line and the downstream fuel return line. A cooling fuel supply line is disposed in fluid communication with the mixing device and the storage tank. The cooling fuel supply line conveys a flow of fuel from the storage tank to the mixing device. The mixing device includes a flow restrictor that is operable to generate a low pressure zone in the mixing device relative to a fluid pressure in the cooling fuel supply line to draw fuel through the cooling fuel supply line and into the mixing device to mix with and cool the flow of heated fuel from the upstream fuel return line.

Accordingly, the mixing device mixes the flow of heated fuel from the internal combustion engine, with the flow of cooling fuel from the storage tank. If the temperature of the flow of heated fuel is greater than the temperature of the flow of cooling fuel, the cooling fuel will have a cooling effect, thereby reducing the temperature of the heated fuel prior to being returned to the fuel storage tank. The flow restrictor, e.g., a Venturi device, is used to generate the low pressure zone, relative to the fluid pressure of the cooling fluid in the cooling fuel supply line. The low pressure zone operates to draw the flow of the cooling fluid into the mixing device to mix with the flow of heated fuel.

DETAILED DESCRIPTION

Referring to the Figures, wherein like numerals indicate like parts throughout the several views, a vehicle is generally shown at20. The vehicle20may include any type, style, and/or configuration of vehicle20that includes a fuel system22for supplying an internal combustion engine24with a supply of combustion fuel. For example, the vehicle20may include, but is not limited to a car, a truck, a tractor, an ATV, a train, etc. Furthermore, while the exemplary embodiment of the fuel system22is described as being incorporated into the vehicle20, it should be appreciated that the fuel system22may be incorporated into some other stationary device having an internal combustion engine24, such as but not limited to a generator or power source. Accordingly, the fuel system22is not limited to use in the vehicle20. In the exemplary embodiment described herein, the internal combustion engine24is described as a diesel engine that combusts diesel fuel. However, it should be appreciated that the fuel system22described herein may be used with other fuels for other engine types.

As noted above, the internal combustion engine24of the exemplary embodiment described herein is a diesel engine. The diesel engine24includes a high pressure fuel pump26, which supplies a plurality of fuel injectors28with highly pressurized fuel. The specific operation of the engine24, the high pressure fuel pump26, and the fuel injectors28are not pertinent to the teachings of this disclosure, and are therefore not described in detail herein.

The fuel system22further includes a fuel storage tank30, a fuel feed line32, a high pressure fuel line34, an upstream fuel return line36, a mixing device38, a downstream fuel return line40, and a cooling fuel supply line42. The fuel storage tank30stores a supply of fuel for use by the internal combustion engine24. The specific size, shape, and/or construction of the fuel storage tank30are not pertinent to the teachings of this disclosure, and are therefore not described in detail herein. The fuel feed line32is disposed in fluid communication with the fuel storage tank30and the high pressure fuel pump26. The fuel feed line32supplies fuel from the storage tank30to the high pressure fuel pump26. The fuel flowing through the fuel feed line32, between the fuel storage tank30and the high pressure fuel pump26, may be referred to herein as the flow of engine supply fuel44. The engine supply fuel is generally indicated by arrows44aligned parallel with the fuel feed line32. The high pressure fuel pump26receives the flow of engine supply fuel44, increases the fluid pressure of the flow of engine supply fuel44, and directs the flow of engine supply fuel44to the high pressure fuel line34. The high pressure fuel line34directs the flow of engine supply fuel44to the fuel injectors28, as is known in the art.

As the fuel circulates from the fuel storage tank30, through the fuel feed line32, the high pressure fuel pump26, and the high pressure fuel line34, the fuel may absorb heat, and increase in temperature. Not all of the fuel circulated to and through the high pressure fuel pump26is consumed by the fuel injectors28during operation of the internal combustion engine24. The portion of the flow of engine supply fuel44that is not used for combustion may be circulated back to the fuel storage tank30. The upstream fuel return line36is disposed in fluid communication with the high pressure fuel line34for receiving the unused portion of the flow of engine supply fuel44. The unused portion of the flow of engine supply fuel44may be referred to herein as the flow of heated fuel46from the high pressure fuel line34. The heated fuel is generally indicated by arrows46aligned parallel with the upstream fuel return line36. Accordingly, the unused portion of the flow of engine supply fuel44is the flow of heated fuel46flowing through the upstream fuel return line36.

The mixing device38is disposed in fluid communication with the upstream fuel return line36, and receives the flow of heated fuel46from the upstream fuel return line36. The downstream fuel return line40is disposed in fluid communication with the mixing device38and the storage tank30. Accordingly, the mixing device38is disposed in fluid communication with and interconnects the upstream fuel return line36and the downstream fuel return line40. The cooling fuel supply line42is disposed in fluid communication with the mixing device38and the storage tank30. The cooling fuel supply line42conveys a flow of cooling fuel48from the storage tank30to the mixing device38. The cooling fuel is generally indicated by arrows48aligned parallel with the cooling fuel supply line42. The mixing device38mixes the flow of the heated fuel46from the upstream fuel return line36and the flow of cooling fuel48from the cooling fuel supply line42to form a flow of mixed fuel50. The downstream fuel return line40conveys the flow of mixed fuel50from the mixing device38back to the storage tank30. The mixed fuel is generally indicated by arrows50aligned parallel with the downstream fuel return line40.

The mixing device38includes what may be referred to as a lifting injector51. As used herein, the term “lifting injector” is defined as a device that uses the Venturi effect of a flow restrictor, e.g., a converging section, to convert pressure energy of a motive fluid to velocity energy, which creates a low pressure zone52that draws in and entrains a suction fluid. As used herein, the term “Venturi effect” is described as the reduction in fluid pressure that results when a fluid flows through a constricted section of a pipe. Accordingly, the lifting injector51of the mixing device38is operable to generate a low pressure zone52in the mixing device38, relative to a fluid pressure in the cooling fuel supply line42, to draw fuel through the cooling fuel supply line42(i.e., the suction fluid) and into the mixing device38to mix with and cool the flow of heated fuel46from the upstream fuel return line36. The lifting injector51may use the flow of heated fuel46from the upstream return line as the motive fluid, described as a first embodiment of the fuel system22and shown inFIGS. 1 and 2, or may alternatively use the flow of the engine supply fuel44from the fuel feed line32as the motive fluid, described as a second embodiment of the fuel system22and shown inFIGS. 3 and 4.

The lifting injector51includes a Venturi device, hereinafter referred to as a flow restrictor54, which is disposed in fluid communication with a flow of motive fuel56. The motive fuel is generally indicated by arrows56. The flow restrictor54is used to induce the venture effect required to operate the lifting injector51. The flow restrictor54is operable to restrict the flow of motive fuel56, thereby increasing a velocity of the flow of motive fuel56and decreasing a fluid pressure of the flow of motive fuel56. The increase in velocity and the decrease in fluid pressure of the motive fluid generates the low pressure zone52within the mixing device38, which creates a suction effect in the cooling fuel supply line42that draws the flow of cooling fluid from the fuel storage tank30, through the cooling fuel supply line42, and into the mixing device38.

The flow restrictor54may include, for example, a device, which includes an aperture58having a reduced diameter60relative to an upstream diameter62of the supply line conducting the flow of the motive fuel56to the lifting injector51, e.g., the upstream fuel return line36or the fuel feed line32. For example, the flow restrictor54may include but is not limited to, a plate defining the aperture58. Alternatively, the flow restrictor54may include a converging section64that narrows in a direction of fluid flow through the lifting injector51to define the aperture58. The direction of fluid flow through the lifting injector51is generally indicated by arrow66, and is in the direction moving from the upstream fuel return line36, to the downstream fuel return line40, and back to the fuel storage tank30. The converging section64includes a converging diameter68that decreases in size with movement in the direction of fluid flow through the lifting injector51.

The lifting injector51may include a diverging section70as well, such as shown in the Figures. However, it should be appreciated that the lifting injector51is not required to include the diverging section70. The diverging section70widens in the direction of fluid flow through the lifting injector51. The downstream fuel return line40is disposed in fluid communication with the diverging section70of the lifting injector51. The diverging section70includes a diverging diameter72that increases in size with movement in the direction of fluid flow through the lifting injector51. The flow of mixed fuel50enters the lifting injector51downstream of the flow restrictor54. For example, and as shown in the Figures, the flow of mixed fuel50enters the lifting injector51between the converging section64and the diverging section70.

The above description of the fuel system22is applicable to both the first embodiment of the fuel system22shown inFIGS. 1 and 2, and the second embodiment of the fuel system22shown inFIGS. 3 and 4. Features common to both the first embodiment of the fuel system22and the second embodiment of the fuel system22, which are described above, are identified throughout all ofFIGS. 1 through 4by their respective reference numerals.

Referring toFIGS. 1 and 2, the first embodiment of the fuel system22is described in greater detail. As noted above, the first embodiment of the fuel system22uses the flow of heated fuel46from the upstream fuel return line36as the flow of motive fuel56for the lifting injector51. Accordingly, the flow restrictor54, and more specifically, the converging section64of the lifting injector51, is disposed in fluid communication with the upstream fuel return line36for receiving the flow of heated fuel46through the flow restrictor54. The flow of heated fuel46from the upstream fuel return line36flows through the lifting injector51, whereby the converging section64restricts the flow of heated fuel46. The flow restrictor54in the lifting injector51, e.g., the converging section64of the lifting injector51best shown inFIG. 2, restricts the flow of heated fuel46from the upstream fuel return line36, which generates the low pressure zone52at or near the aperture58of the flow restrictor54. The low pressure zone52includes a fluid pressure that is lower than a fluid pressure of the fuel in the cooling fuel supply line42, which operates to draw fuel from the storage tank30, through the cooling fuel supply line42, and into the mixing device38. The fuel from the cooling fuel supply line42is drawn into the diverging section70of the lifting injector51, along with the flow of heated fuel46from the upstream fuel return line36, to form the flow of mixed fuel50in the downstream fuel return line40. If the fuel in the storage tank30is at a temperature that is less than the temperature of the flow of heated fuel46in the upstream fuel return line36, the mixing of the flow of cooling fuel48with the flow of heated fuel46will decrease the temperature of the heated fuel46, such that the flow of mixed fuel50includes a temperature that is less than the flow of heated fuel46, but higher than the flow of cooling fuel48.

Referring toFIGS. 3 and 4, the second embodiment of the fuel system22is described in greater detail. As noted above, the second embodiment of the fuel system22uses the flow of engine supply fuel44from the fuel feed line32as the flow of motive fuel56for the lifting injector51. Accordingly, the flow restrictor54, and more specifically, the converging section64of the lifting injector51, is disposed in fluid communication with the fuel feed line32for receiving a portion of the flow of the engine supply fuel44through the flow restrictor54. The fuel feed line32may include a branch line74for supplying the lifting injector51.

The fuel system22may include a control valve76that is selectively operable to control fluid flow through the fuel feed line32, to the mixing device38. The control valve76is positioned in the branch line74so as to not interrupt fluid flow to the internal combustion engine24. The control valve76may be actuated to regulate fluid flow through the lifting injector51. For example, the control valve76may completely close fluid flow through the lifting injector51, or may allow variable amounts of fluid flow through the lifting injector51to control the amount of suction generated within the mixing device38. The control valve76may include any type and/or style of valve suitable for use in a fuel system22. The control valve76may be controlled by a vehicle20controller, such as but not limited to an engine control module or other similar device.

The mixing device38includes a mixing chamber78that is disposed in fluid communication with the upstream fuel return line36, the downstream fuel return line40, and the cooling fuel supply line42. The flow of heated fuel46is mixed with the flow of cooling fuel48, within the mixing chamber78, prior to being drawn into and discharged through downstream fuel return line40. As noted above, the flow restrictor54, and more specifically, the converging section64of the lifting injector51, is disposed in fluid communication with the fuel feed line32via branch line74for receiving the flow of engine supply fuel44through the flow restrictor54. The flow of engine supply fuel44from the fuel feed line32flows through the lifting injector51, whereby the converging section64restricts the flow of heated fuel46. The flow restrictor54in the lifting injector51, e.g., the converging section64of the lifting injector51best shown inFIG. 4, restricts the flow of engine supply fuel44from the fuel feed line32, which generates the low pressure zone52at or near the aperture58of the flow restrictor54.

The low pressure zone52includes a fluid pressure that is lower than a fluid pressure of the cooling fuel48in the cooling fuel supply line42, which draws fuel from the storage tank30, through the cooling fuel supply line42, and into the mixing chamber78. The cooling fuel48mixes with the heated fuel46in the mixing chamber78. The fuel from mixing chamber78is drawn into the diverging section70of the lifting injector51, to form the flow of mixed fuel50in the downstream fuel return line40. If the fuel in the storage tank30is at a temperature that is less than the temperature of the flow of heated fuel46in the upstream fuel return line36, then the mixing of the flow of cooling fuel48with the flow of heated fuel46will decrease the temperature of the heated fuel46, such that the flow of mixed fuel50includes a temperature that is less than the flow of heated fuel46, but higher than the flow of cooling fuel48.