EP2488742A2

EP2488742A2 - Fuel economizer fuel vapor system for internal combustion engine

Info

Publication number: EP2488742A2
Application number: EP10824074A
Authority: EP
Inventors: Christopher Smart
Original assignee: Advanced Mileage Technologies LLC
Current assignee: Advanced Mileage Technologies LLC
Priority date: 2009-10-15
Filing date: 2010-10-14
Publication date: 2012-08-22
Also published as: US20110091286A1; JP2013508600A; EP2488742A4

Abstract

A fuel vaporizer for an internal combustion engine having a closed pressure chamber defining a volume, to be heated, and a liquid fuel supply system disposed to emit a liquid fuel spray. The closed pressure chamber may be constructed and arranged relative to the heat-transfer surface to establish between the at least one outlet and the heat-transfer surface a mixing domain in which the fuel spray, as it progresses through the volume from the outlet, is substantially heated and vaporized by mixing with re-circulated, heated fuel vapor that previously has moved over and received heat from the heat transfer surface. The fuel vaporizer may be associated with a vapor outflow passage through which pressurized vapor exits the closed pressure chamber for supply to said at least one combustion region. The heat-transfer surface may be arranged to be heated by engine coolant circulating around the exterior of the closed pressure chamber.

Description

FUEL ECONOMIZER FUEL VAPOR SYSTEM

FOR INTERNAL COMBUSTION ENGINE

BACKGROUND OF THE INVENTION

1. Field of the Invention.

The present invention relates to a system that transforms liquid fuel into fuel vapor to improve combustion in internal combustion engines.

2. Prior Art.

The manner in which fuel is provided to an engine significantly affects both fuel efficiency and exhaust emissions. In a piston engine with a carburetor, liquid gasoline is introduced centrally to a flow of combustion air, following which the air- fuel mixture is divided and distributed to the engine cylinders. In a piston engine with fuel injectors at the cylinders, pressurized liquid fuel is forced through nozzles of the injectors to inject sprays of liquid fuel particles. The sprays are injected into combustion air at the inlet ports of the cylinders or directly into the combustion regions. Incomplete combustion of the fuel in these and other engines detrimentally affects fuel economy and produces harmful emissions.

Over many decades, suggestions have been made to pre-vaporize fuel as a way to improve fuel efficiency and decrease emissions of internal combustion engines.

Cooke (U.S. Patent No. 5,746,188) and Shetley (U.S. Patent No. 6,758,194) illustrate examples of fuel vaporization systems using electric heating elements.

Notwithstanding the foregoing, there is considerable room to improve fuel efficiency and decrease emissions. SUMMARY OF THE INVENTION

A fuel vaporizer for an internal combustion engine, includes a first closed chamber defining a first volume enclosed at least partially by a wall, a heat transfer surface within the first closed chamber, a second closed chamber at least partially surrounding the first closed chamber defining a second volume, a liquid fuel supply system comprising a liquid fuel supply line and a fuel injector, the fuel injector disposed to emit into the first volume, under super-atmospheric pressure, an expanding pattern of liquid fuel spray from at least one orifice spaced from the heat transfer surface. A thermal fluid system is configured to introduce heated fluid into the second volume and transfer heat from the heated fluid through all of the first closed chamber, and a vaporized fuel outlet is configured to direct vaporized fuel from the first closed chamber to a combustion fuel supply line that supplies fuel to at least one combustion region of the engine.

In some embodiments, the heat transfer surface of the first closed chamber is the wall of the first closed chamber. Optionally, the heat transfer surface may be a member of increased surface area that is in thermal communication with the wall of a supply stem.

The vaporizer system may also include an optional pressure relief valve that may be configured to open when the pressure inside the first closed chamber exceeds a predetermined threshold and direct vaporized fuel to the liquid fuel supply system. The first closed chamber may also include an upper end and a lower end, wherein the vaporized fuel outlet may be configured on the upper end and the liquid fuel return may be configured on the lower end.

Some embodiments may provide a method of supplying fuel to at least one combustion region of an internal combustion engine including introducing a heated fluid into a volume, the volume at least partially surrounding a vapor chamber, transferring heat from the heated fluid to the vapor chamber, supplying fuel to the vapor chamber via a liquid fuel supply line, emitting into the vapor chamber a substantially liquid fuel at super-atmospheric pressure, vaporizing the substantially liquid fuel in the vapor chambers and expelling the vaporized fuel from the vapor chamber to a combustion chamber fuel supply line.

Methods of the present invention may further include receiving, at a liquid fuel bypass valve, a signal indicating that the vaporized fuel from the vapor chamber is not sufficient to meet the fuel demands of the combustion region, at least partially opening the liquid fuel bypass valve, and bypassing the vapor chamber by diverting liquid fuel from the liquid fuel supply line to the combustion chamber fuel supply line. Methods may also include returning liquid fuel from the vapor chamber to the liquid fuel supply line. Further, methods may include opening a pressure relief valve upon the pressure in the vapor chamber exceeding a predetermined threshold.

Embodiments of the present invention may include a fuel vaporizer for an internal combustion engine comprising a closed pressure chamber defining a volume, a heat transfer surface associated with the volume and arranged to be heated, and a liquid fuel supply system disposed to emit into the volume, under super-atmospheric pressure, an expanding pattern of liquid fuel spray from at least one orifice spaced from the heat transfer surface, the liquid fuel supply system emitting fuel into the volume for vaporization and supply to at least one combustion region of the internal combustion engine. The closed pressure chamber and the liquid fuel supply system may be constructed and arranged relative to the heat-transfer surface to establish between the at least one outlet and the heat-transfer surface a mixing, domain in which the fuel spray, as it progresses through the volume from the outlet, is substantially heated and vaporized by mixing with recalculated, heated fuel vapor that previously has moved over and received heat from the heat transfer surface. The fuel vaporizer may be associated with a vapor outflow passage through which pressurized vapor exits the closed pressure chamber for supply to said at least one combustion region. The heat-transfer surface may be arranged to be heated at least partially by end a coolant circulating around the exterior of the closed pressure chamber. Embodiments may further include a second closed chamber that at least partially surrounds the closed pressure chamber and defines a volume through which the engine coolant is circulated. Further, embodiments may include an engine coolant inlet and an engine coolant outlet where the engine coolant entering through the engine coolant inlet is of a higher temperature than the engine coolant exiting through the engine coolant outlet.

Embodiments may also include a flow control associated with the vaporizer outflow passage, the flow control including at least one fuel vapor injector each of the at least one fuel vapor injectors communicating directly or indirectly with a respective at least one combustion region adapted to be actuated in response to end were requirements, the fuel vaporizer being constructed and arranged to enable flow of pressurized fuel vapor to the engine while maintaining substantial super-atmospheric pressure within the volume in which the vapor is generated. The fuel vaporizer may also include a liquid fuel return outlet.

The details of selected designs within the scope of the invention are set forth in the accompanying drawings and the description below.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross-sectional view of a fuel vaporizer system for an internal combustion engine according to an exemplary embodiment of the present invention;

Figure 2 is a cross-sectional view of a fuel vaporizer system for an internal combustion engine according to another exemplary embodiment of the present invention;

Figure 3 is a simplified schematic illustration of a fuel system including a fuel vaporizer system according to an exemplary embodiment of the present invention; and

Figure 4 is a simplified schematic illustration of the present invention in relation to an internal combustion engine and fluid coolant system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments discussed herein are merely illustrative of specific manners in which to make and use the invention and are not to be interpreted as limiting the scope of the instant invention.

While the invention has been described with a certain degree of particularity, it is to be noted that many modifications may be made in the details of the invention's construction and the arrangement of its components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification.

Preferred embodiments of the present invention are illustrated in Figures 1 through 4 wherein engine coolant is used to heat the vapor chamber. In the vaporizer embodiment illustrated in Figure 1 , a vapor chamber 900 is at least partially surrounded by a coolant chamber 905 thereby creating a coolant cavity 910.

In known liquid cooled internal combustion engines, a liquid such as a coolant is delivered to and through channels running through the engine and cylinder head. The liquid may be water but is commonly a mixture of water and anti-freeze, such as ethylene glycol or propylene glycol. The coolant is thereafter delivered to and through a radiator, so that heat is transferred from the fluid inside to the atmospheric air outside. A pump, such as a centrifugal pump, circulates the coolant through the system. The coolant operates in a closed system and is recirculated.

In the embodiment in Figure 1 , relatively hot coolant enters through the coolant inlet 915 into the coolant cavity, flows around the exterior of the vapor chamber 900 and exits the coolant cavity 910 at the coolant exit 920. The hot coolant serves to heat the vapor chamber 900 by transferring heat from the coolant to the relatively cooler vapor chamber. In various embodiments, the exterior of the vapor chamber may include fins or other surface-enhancing elements to increase the amount of heat transfer from the coolant to the vapor chamber 900. Further, the vapor chamber may be made of a material with a high thermal conductivity to promote heat transfer from the coolant through the walls of the vapor chamber to the fuel in the vapor chamber. The coolant chamber 905 may be made of an insulative material or material with a low thermal conductivity to promote retention of heat within the coolant chamber 905, further promoting heat transfer to the vapor chamber 900.

In the embodiment of Figure 1, the coolant may be drawn from a standard cooling system of a vehicle as is well known in the art, preferably when the coolant is at or near its highest temperature such as at the thermostat. Directing the highest temperature coolant available to the vaporize provides more efficient operation.

Further to the embodiment illustrated in Figure 1 , the fuel inlet 925 for the vapor chamber may be a fuel injector as described above. A vaporized fuel outlet 930 is provided to allow vaporized fuel to exit the vapor chamber 900 for supplying to at least one combustion region. The vaporized fuel outlet 930 is shown as being at the same end of the vapor chamber 900 as the fuel inlet 925, i.e., the vaporized fuel outlet is not generally aligned with the fuel injector along the direction in which fuel is injected. This arrangement helps to promote a recirculation of fuel vapor in the chamber before the vapor exits the chamber through the vaporized fuel outlet 930. A baffle 935 may be provided to preclude newly injected, substantially liquid fuel from being expelled through the vaporized fuel outlet 930. The baffle 935 may further serve as a heat sink to aid in the vaporization of the newly injected fuel entering through the fuel inlet 925.

A liquid fuel outlet 940 may be provided in the vapor chamber 900 to allow liquid fuel to exit the vaporization volume 901. Liquid fuel remaining in the vapor chamber 900 may be detrimental to the generation of vapor in the chamber as the liquid fuel may absorb heat from the coolant and the liquid fuel compromises the volume available for the fuel entering the vapor chamber to be vaporized. The liquid fuel outlet may be isolated from the coolant cavity 910 by a shield 945 to prevent any exiting liquid fuel from further removing heat from the system. The liquid fuel removed from the vapor chamber 900 may be returned to the fuel tank or to the fuel line supplying the vaporizer.

Another exemplary embodiment of the present invention is illustrated in the vaporizer of Figure 2. The embodiment of Figure 2 is similar to that of Figure 1. The vapor chamber, 950 is substantially surrounded by a coolant chamber 955 forming a coolant cavity 960 and includes both a coolant inlet 965 and a coolant outlet 970. The illustrated embodiment further includes a fuel inlet 975, shown as a fuel injector, a vaporized fuel outlet 980 for supply to at least one combustion region, and a liquid fuel outlet 985 for return to the fuel system. The embodiment of Figure 2 further includes a heat-exchange element 990 for efficient heat transfer between the vapor chamber 950 and the incoming fuel spray. The heat-exchange element may be a mesh or a finned member, but generally includes a region of greater surface area than would be available without the heat exchange element 990. The increased surface area provides a greater heat-exchange surface available to the incoming fuel surface providing more complete and efficient vaporization of the liquid fuel. The heat-exchange element may be of any material but is preferably of a material with a high thermal conductivity to promote heat exchange between the vapor chamber 950 wall and the heat-exchange element.

The fuel vaporization system of the present invention, particularly embodiments that do not include electrical heating elements, may further include provisions to ensure the combustion regions are adequately supplied with fuel under varying conditions such a cold starts and heavy load scenarios.

Figure 3 is a schematic illustration of an exemplary embodiment of the present invention including exempt cold-start and a high load provisions. Electrical paths are represented by dashed lines while fluid paths are represented by solid lines. The vaporizer 1000 represented diagrammatically, includes a coolant inlet 1005 and a coolant outlet 1010. The vaporizer 1000 further includes a liquid fuel inlet 1015 and a vaporized fuel outlet 1020. A liquid fuel outlet may be included; however, for ease of explanation the liquid fuel outlet is not illustrated. Liquid fuel is supplied from the fuel tank via fuel line 1025 and fuel line 1030 supplies fuel in liquid and/or vapor form to at least one combustion region of an engine. A high-load liquid fuel bypass valve 1040 and a cold start liquid fuel by-pass valve 1045 are illustrated separately for ease of explanation; however, these valves may, be combined into a single valve while providing the same functionality, While the general components of the schematic have been described, further operating, scenarios will be described herein.

Referring again to Figure 3 under normal operating conditions (i.e., engine coolant at operating temperature, normal load conditions) the heated engine coolant enters the vaporizer system through the coolant inlet line 1005 and exits the vaporizer system through the coolant outlet line 1010. The liquid fuel is introduced from the fuel tank, along the liquid fuel line 1025, through valve 1055, and into the vaporizer liquid fuel inlet 1015. Vaporized fuel exits the vaporizer at the vaporized fuel outlet 1020, through valve 1055. and to the at least one combustion region of the engine through the fuel line 1030.

In the illustrated embodiment, under cold start conditions, the temperature sensor 1070 in communication with the coolant circulating in the vaporizer 1000 indicates that the coolant is not teat the normal operating temperature, generally between 180°F and 220°F. An electrical signal is sent from the temperature sensor to the cold-start liquid fuel bypass valve 1045 opening the valve, allowing liquid fuel to pass from the fuel line 1025 to line 1030 in liquid form to ensure the at least one combustion region receives the necessary fuel for proper operation. Further, when the coolant temperature is below normal operating temperature, the temperature sensor 1070 sends a signal to valve 1085 and valve 1055 to close, or to remain closed. This prevents liquid fuel from entering the vaporizer which would fill the vaporizer with liquid fuel and delay or prevent the vaporizer from reaching the temperature necessary to vaporize the fuel.

While operating under normal conditions as defined above, an engine may experience demand for high power, which may occur in a vehicle engine while accelerating, passing, or going up hill or in a generator engine when the wattage demand is increased by an added electrical load. Under these conditions, an instantaneous spike in fuel demand may not be sufficiently accommodated by a vaporizer sized for optimum efficiency for the application; therefore additional fuel may be required. In the illustrated schematic, a high-load liquid fuel bypass valve 1040 is provided to allow liquid fuel to pass the vaporizer 1000 sending liquid fuel from fuel line 1025, through the high- load liquid fuel by-pass valve 1040, and through fuel line 1030 to the combustion region. In such a scenario, valve 1085 and valve 1055 may or may not be closed as the liquid fuel bypassing through valve 1040 may supplement the vaporized fuel produced by the vaporizer. The high-load liquid fuel bypass valve control signal 1080 may be provided by an electrical signal from a control module, such as from a vehicle's power control module (PCM or a generator's engine controller, or a vacuum switch using increased intake manifold vacuum as an indication of increased power demand.

Referring again to the schematic of Figure 3, after a vaporizer has been operating at steady-state operating temperatures for a time, the vaporizer will retain a significant amount of heat. When the engine is turned off, the coolant flow to the vaporizer may also cease, though generation of vapor within the chamber may continue for some time, particularly if any fuel puddling had previously occurred within the vapor chamber. In the illustrated example, a blow-off valve 1050 is provided to allow excess pressure built up in vaporizer to be returned safely to the fuel system while limiting the maximum pressure in the vapor chamber. A fuel-pressure regulator 1075 may provide a signal to a valve, or the valve may be configured to open upon reaching a pre-determined threshold pressure.

Testing of the present system show marked improvement in the following areas of governmental emissional requirements - lowered hydrocarbon (HC) content of at least 25 %, lowered nitrous oxide (NOx) content of at least 70% and raised oxygen (0₂) content of at least 75%.

Whereas, the present invention has been described in relation to the drawings attached hereto, it should be understood that other and further modifications, apart from those shown or suggested herein, may be made within the spirit and scope of this invention.

Claims

WHAT IS CLAIMED IS:

1. A fuel vaporizer system for an internal combustion engine, comprising:

a first closed chamber defining a first volume, said closed chamber having a heat transfer surface, wherein said first closed chamber is a pressure chamber having a cylindrical center and spherical ends;

a second closed chamber at least partially surrounding the first closed chamber defining a second volume;

a liquid fuel supply system comprising a liquid fuel supply line to emit into the first volume an expanding pattern of liquid fuel spray from at least one orifice spaced from the heat-transfer surface;

a thermal fluid system from said engine configured to circulate heated fluid through the second volume and transfer heat from the heated fluid through the first closed chamber and vaporize said liquid fuel;

a vaporized fuel outlet configured to direct vaporized fuel from the first closed chamber to supply fuel to at least one combustion region of the internal combustion engine via a combustion fuel supply line; and

a pressure relief valve configured to open when the pressure inside the first closed chamber exceeds a predetermined threshold and to direct vaporized fuel to the liquid fuel supply system.

2. A fuel vaporizer system according to Claim 1 wherein the heat transfer surface comprises a wall.

3. A fuel vaporizer system according to Claim 2 wherein the heat transfer surface further comprises a member of increased surface area in thermal communication with the wall of the first closed chamber.

4. A fuel vaporizer system according to Claim 1 further comprising a liquid fuel bypass configured to allow liquid fuel to pass from the liquid fuel supply line to the combustion fuel supply line.

5. A fuel vaporizer system according to Claim 4 wherein the liquid fuel bypass is configured to be opened only when the first closed volume cannot supply sufficient vaporized fuel to satisfy demands of the internal combustion engine.

6. A fuel vaporizer system according to Claim 1 further comprising a liquid fuel return drain outlet configured to return non- vaporized fuel to the liquid fuel supply system.

7. A fuel vaporizer system according to Claim 1 wherein the first closed chamber includes an upper end and an opposed lower end, wherein the vaporized fuel outlet is arranged proximate the upper end.

8. A fuel vaporizer system according to claim according to Claim 7 wherein a fuel spray nozzle is located proximate the upper end.

9. A method of supplying fuel to at least one combustion region of an internal combustion engine, comprising:

circulating a heated fluid through a chamber that at least partially surrounds a vapor chamber; transferring heat from the heated fluid to the vapor chamber;

supplying substantially liquid fuel to the vapor chamber via a liquid fuel supply line;

vaporizing the substantially liquid fuel in the vapor chamber to create a super- atmospheric pressurized fuel vapor;

expelling the super-atmospheric pressurized fuel vapor from the vapor chamber to a combustion chamber fuel supply line;

opening a pressure relief valve and directing vaporized fuel to the liquid fuel supply system if pressure in the vapor chamber exceeds a predetermined threshold; and ensuring sufficient fuel to meet fuel demands of the combustion region by: receiving an electrical signal at a liquid fuel bypass valve if the super- atmospheric pressurized fuel vapor from the vapor chamber is not sufficient to meet fuel demands of the combustion region;

opening, at least partially, the liquid fuel bypass valve upon receiving the signal; and

at least partially bypassing the vapor chamber by diverting liquid fuel from the liquid fuel supply line to the combustion chamber fuel supply line through the liquid fuel bypass valve.

10. A method of supplying fuel to at least one combustion region according to Claim 9, further comprising:

returning liquid fuel from the vapor chamber to the liquid fuel supply line.

11. A fuel vaporizer for an internal combustion engine, the fuel vaporizer comprising: a closed pressure chamber defining a volume;

a heat-transfer surface associated with the volume and arranged to be heated; a liquid fuel supply system disposed to emit into the volume, under super- atmospheric pressure, an expanding pattern of liquid fuel spray from at least one orifice spaced from the heat-transfer surface, the liquid fuel supply system emitting fuel into the volume for vaporization and supply to at least one combustion region of the internal combustion engine; and a flow control comprising at least one fuel vapor injector, each of the at least one fuel vapor injectors communicating directly or indirectly with a respective at least one combustion region and adapted to be actuated in response to engine power requirements, such that pressurized fuel vapor may flow to the engine while substantial super-atmospheric pressure is maintained within the closed pressure chamber;

the closed pressure chamber and the liquid fuel supply system being constructed and arranged relative to the heat-transfer surface to establish between the at least one orifice and the heat-transfer surface a mixing domain in which the fuel spray, as it progresses through the volume from the orifice, is substantially heated and vaporized by mixing with recirculated, heated fuel vapor that previously has moved over and received heat from the heat transfer surface;

the fuel vaporizer being associated with a vapor outflow passage through which pressurized vapor exits the closed pressure chamber for supply to said at least one combustion region; and

the heat-transfer surface arranged to be heated at least partially by engine coolant circulating around the exterior of the closed pressure chamber. 15

12. A fuel vaporizer according to Claim 11 , wherein a second closed chamber at least partially surrounds the closed pressure chamber and defines a volume through which the engine coolant is circulated.

13. A fuel vaporizer according to Claim 12, where the second closed chamber further comprises an engine coolant inlet and an engine coolant outlet, wherein the engine coolant entering through the engine coolant inlet is of a higher temperature than the engine coolant exiting through the engine coolant outlet.

14. A fuel vaporizer according to Claim 11, the closed pressure chamber further comprising a liquid fuel return outlet configured to return non-vaporized fuel to the liquid fuel supply system.