Patent Application
20110068188
Fuel injectors are commonly used to supply fuel to the combustion chamber of an engine. The combustion occurs as soon as the injected fuel spray (fuel plume) has mixed with the air within combustible limits. The following are involved in aiding the bursting of the fuel droplets in the fuel plume in order to start the combustion process: air entrainment (which mixes air with fuel droplets), vaporization, homogenization, pressure, and heat. In a diesel engine, combustion already begins before homogenization begins.
The fuel droplet size typically has a Santer Mean Diameter (SDM) of, for example, approximately 10 micron-meters or less. SDM is measured as a 3rd power of volume and 2nd power of surface. The fuel plume has a high kinetic energy, with typical speed within the range of, for example, approximately 500 meters-per-second to approximately 700 meters-per second. The fuel plume will typically have an opening angle of approximately 3 degrees to approximately 4 degrees.
Two current examples of common types of fuel injector tips that are used are the MicroSac Tip and the VCR tip. Referring initially to
In a standard engine, the multiple fuel injection passages 160 form an umbrella-like arrangement. As will be discussed below, embodiments of the invention can be used with a fuel injector that has the MicroSac tip or the VCR tip.
It would be advantageous to improve the process of mixing of fuel and air, in order to achieve more efficient combustion. Therefore, improvements in the current technology would be desirable in order to overcome current constraints and deficiencies.
Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.
In the description herein, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details, or with other apparatus, systems, methods, components, materials, parts, and/or the like. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of embodiments of the invention.
In an embodiment of the invention as shown in
In an embodiment of the invention as shown in
As a non-limiting example, the fuel injection passage 305 has a diameter D1 of approximately 0.15 mm while the air passage 315 has a diameter D2 of approximately 0.08 mm. However, D1 and D2 can be at other values. Also, as will be discussed below, each of the diameters D1 and D2 are not required to be constant.
In a preferred embodiment of the invention, the air passage diameter D2 (i.e., second diameter D2) of the air passage 325 is less than the fuel injection passage diameter D1 (i.e., first diameter D1) of the fuel passage 305.
In an embodiment of the invention as shown in
In an embodiment of the invention as shown in
In an embodiment of the invention as shown in
The features of various embodiments of the invention can be used with a fuel injector that has a MicroSac tip, a VCR tip, or other injector tip types that are currently available or that may be developed as the state of the art improves.
The air passage outlet 339 of air passage 315 is connected at a location 340 which is between the fuel injection passage inlet 335 and fuel injection passage outlet 336 of the fuel injection passage 305. The location 340 in the fuel injection passage 305 will contain an opening 341 for receiving the air flow 345 that is flowing along the air passage 315. The opening 341 will also permit the air flow 345 to mix with fuel 350 that is flowing along the fuel injection passage 305. The fuel 350 will first flow along the inner cylinder wall 355 and then will flow along the fuel injection passage 305. The fuel 350 will then exit from the outlet 336 as a fuel plume 360. The fuel plume 360 will contain fuel droplets and air 345 that is entrained with the fuel droplets.
The injection pressure for the fuel 350 is, for example, approximately 2,000 bar or other suitable values. This large amount of pressure can lead to the compressibility of the fuel liquid at up to, for example, approximately 5% to approximately 6%. Additionally, the injector tip 301 can have, for example, approximately 280 degrees to approximately 300 degrees of heat.
The fuel 350 can be, for example, diesel, gasoline, ethanol, ammonia, or other types of fuel such as other hydrocarbons, alcohols, or other diesel. It is also noted that embodiments of the invention can be used for direct injection or other types of fuel injections such as, for example, manifold injection.
The location 340 is between the fuel injection passage inlet 335 and fuel injection passage outlet 336. In one preferred embodiment, the location 340 is at an approximate midpoint in the passage 305 between the ends 335 and 336.
The fuel plume 360 exits the fuel passage 305 via outlet 336 into a combustion chamber which is shown symbolically as chamber 362 in
The air flow 345 (which flows along the air passage 315) is generated, for example, from the natural engine suction or pressurized flow from a turbocharger or supercharger, from air in the chamber 362 or from other suitable air generation sources. Standard air flow driving devices (not shown in
The passages 305 and 315 can be metal pipes, or metal alloys, iron, or other suitable materials that form the cylinders of passages 305/315. The passages 305/315 can be connected to each other by use of standard methods such as welding, molding, or other suitable known techniques for connecting metal materials, metal alloys, iron, or other suitable passages to each other.
Note that additional fuel passages 305 (for permitting fuel flow) can be connected to the injector tip 301. For example, an additional fuel passage (not shown in
The fuel plume 360 will be an air-fuel mixture that is exiting from the fuel injection passage outlet 336 and will reach a certain depth penetration (i.e., length) into the combustion chamber 362, and will also roll up adjacent to the injector tip 301 due to the back pressure in the surrounding air in the combustion chamber 362. The core of the air-fuel mixture (in the plume 360) is liquid formed by the fuel droplets that travel together. The fuel droplets in the air-fuel mixture will burst up during the conversion of the kinetic energy of the flow of the air-fuel mixture and vaporize partly, which delays the combustion due to the removal of the vaporization heat. For combustion to occur, the correct amount of fuel and correct amount of air are needed to be present within the combustion limits.
By connecting the air passage 315 to the fuel injection passage 305 at location 340, an enhanced mixing of fuel 350 and air 345 in the fuel injection passage 305 is achieved, prior to fuel combustion in the combustion chamber 362 and to take advantage of the Venturi principle during the mixing of fuel and air prior to combustion. The air flow 345 will enter via the air passage inlet 338, will flow along the air passage 315, and will then mix with the fuel 350 in the fuel injection passage 305. The air-fuel mixture (which is formed due to mixing of air flow 345 with the fuel 350 and due to the air entrainment in the fuel 350) will exit from the fuel injection passage outlet 336 as a fuel plume 360 which is formed by an air-fuel mixture.
Since there is more air content in the air-fuel mixture of the plume 360 that exits the outlet 336 (due to the increased air entrainment provided by the air passage 315 to the fuel 350 in the fuel passage 305), the plume angle 365 of the fuel plume 360 will be wider, as compared to the plume angle that is achieved by previous approaches. The larger surface area of the plume 360 (due to the wider plume angle 365) results in the surrounding air in chamber 362 in breaking down the fuel droplets (in the plume 360) at a faster rate. The wider plume angle 365 can also result in a shorter length of the plume 360. Since the plume 360 will have a wider plume angle 365, the fuel droplets (in the plume 360) will be smaller in size and will disintegrate more quickly, resulting in an improved and efficient fuel combustion process.
In contrast, in current technology, there is a longer ignition delay due to the rich fuel mixture that is received by the combustion chamber and due to the vaporization heat that is extracted during vaporization. Soot and particulates are formed due to the rich fuel mixture and insufficient air, because the meeting of air and fuel does not happen in a desirable way or time.
On the other hand, an embodiment of the invention provides more air 345 to the fuel stream 350 at an earlier time as compared to conventional technology, and consequently, provides a wider plume angle 365, as discussed above. As a result, the fuel droplets will disintegrate at a faster rate in the combustion chamber 362 and the soot formation problems of previous approaches are advantageously avoided or reduced.
The passages 505 and 515 are non-perpendicular to each other, and, therefore, the angle B3 between the passages 505 and 515 is acute. For example, the angle B3 is 80 degrees or another acute angle value. In another embodiment of the invention, the angle B4 is 90 degrees, and, therefore, the passages 505 and 515 are perpendicular to each other.
The fuel injection passage 505 is connected via injection hole A13 to the injection tip 301, and the air passage 515 that is connected to the fuel injection passage 505 at location 540. Since the inlet 535 and the outlet 536 are conical, a Venturi is formed at the location 540.
The conical inlet 535 reduces the flow restriction on the fuel that is entering into the fuel injection passage 505. A conical inlet 535 (or a substantially rounded inlet) reduces cavitation in the fuel injection passage 505. Cavitation is caused by burbling on the passage inner wall near the intake opening that receives the fuel flow because the fuel flow would not immediately contact that passage inner wall. When the flow pressure at that passage inner wall falls below the vapor pressure, cavitation occurs and this can lead to the tearing of parts of the passage material. Therefore, a conical inlet 535 (or a substantially rounded inlet) advantageously reduces the occurrences of cavitation.
Since the inlet 535 and outlet 536 of the fuel injection passage 505 are conical, the passage 505 will not have a constant diameter D1. Instead, the fuel injection passage 505 will have a diameter D1 that varies in value, depending on the particular location along the fuel injection passage 505. For example, at location 540 where the air passage 515 connects to the fuel injection passage 505, the diameter DM of the fuel injection passage 505 is at a minimum value (e.g., approximately 0.08 mm). The diameter Dinlet (e.g., approximately 0.12 mm) at inlet 535 of fuel injection passage 505 and the diameter Doutlet (e.g., approximately 0.12 mm) at outlet 536 of fuel injection passage 505 are each greater than the diameter DM at location 540, in order to have the Venturi in the fuel injection passage 505. In other words, Dinlet>DM and Doutlet>DM.
Therefore, the fuel injection passage 505 will not be cylindrical in shape, but will instead be a conical shape from the inlet 535 and from the outlet 536, with each of the inlet 535 and outlet 536 having a larger diameter than the diameter DM at location 540. Since Dinlet>DM and Doutlet>DM, a Venturi is present in the fuel passage 505. As a result, a depression occurs in the fuel flow 350 in the fuel injection passage 505 and air can be efficiently entrained in the fuel flow in fuel injection passage 505.
As known to those skilled in the art, the Venturi effect is described by Bernoulli's Equation:
P
1+(1/2)(d1)(v1)2=P2+(1/2)(d2)(v2)2 (1)
where,
P1=pressure at the inlet of the Venturi;
P2=pressure at the throat of the Venturi;
d1=air density at the inlet of the Venturi;
d2=air density at the throat of the Venturi;
v1=air velocity at the inlet of the Venturi; and
v2=air velocity at the throat of the Venturi.
Based on the law of conservation of impulse (Newton/second), mass can neither be created nor destroyed in a closed system, and as such, the volumetric flow rate at a first area A must equal the volumetric flow rate at a second area A″. When area A″ is smaller than area A, the flow traveling through A″ must travel faster in order to maintain the same volumetric flow rate. The increased velocity of the flow results in a decrease in pressure according to the Bernoulli equation.
Therefore, there is less pressure at location 540 where the air flow 345 meets that fuel 350. Therefore, air entrainment in the flow of fuel 350 is efficiently achieved at location 540 because of the lesser pressure at this location.
An air passage 615 is connected to the fuel passage 605 at location 640. The air passage 615 can be perpendicular to the fuel passage 605 or can be at an acute angle B1 (e.g., approximately 80 degrees) with respect to fuel passage 605.
The fuel passage 605 will not have a constant diameter D1. Instead, the fuel passage 605 will have a diameter D1 that varies in value, depending on the particular location along the fuel passage 605. For example, at location 640 where the air passage 615 connects to the air passage 605, the diameter DM of the fuel passage 605 is at a minimum value (e.g., 0.08 mm). The diameter Dinlet at inlet 635 of fuel passage 605 and the diameter Doutlet at outlet 636 of fuel passage 605 are each greater than the diameter DM at location 630. In other words, Dinlet>DM and Doutlet>DM.
In an embodiment of the invention, the inlet 635 will have a substantially bottleneck shape or other geometric shape. The outlet 636 can also have a substantially bottleneck shape (as shown in
Note also that the conical air passage inlet 538 of
The inlet 735 can also have a bottleneck shape (as shown in
Note also that the conical air passage inlet 538 of
The centerlines 860A and 860B (of air passages 815A and 815B, respectively) are substantially parallel or can have a slight angle difference. For example, the centerline 860A and 860B can have zero degrees of angle difference (i.e., are parallel) or can have an acute angle difference (e.g., approximately 10 degrees or less).
Since two air passages 815A and 815B are provided, more air 345 are provided for air entrainment in the fuel 350. The air passages 815A and 815B also provide the swirl 870 that provides a twisting movements to the fuel 225. The swirl 870 is an air flow direction that will aid in bursting the fuel droplets in the fuel plume that exits the fuel passage 805 because the swirl 870 (in a counter-clockwise direction in the example of
The air passages 1015A/1015B are tangentially offset in configuration. For example, as best shown in
As another option in an embodiment of the invention, the tangential offset to the air passages 1015A and 1015B is based on distance between the respective tangential junctions of the air passages 1015A and 1015B. For example, in
The tangentially offset air passages 1115A/1115B provide a swirl (rotation) movement to fuel in the fuel passage 1105. The air passages 1115A/1115B are tangentially offset in configuration. For example, this tangential offset is achieved by connecting the air passage 1115A to the front surface of the fuel passage 1105 and connecting the air passage 1115B to the rear surface of the fuel passage 1105.
To permit improved air flow 345 into the air passages 1115A and 1115B, each of the inlet 1138A and inlet 1138B has a geometric shape, such as, for example, conical shape, bell-mouth shape (funnel shape), bottleneck shape, or another suitable geometric shape that reduces the flow restriction on the air 345. In the example of
Additionally, the outlet 1152A (of air passage 1115A) and the outlet 1152B (of air passage 1115B) can be rounded (or expanded) in shape, as best illustrated in
The conical jet 1105A reduces cavitation. The conical jet 1105A can be a conical passage with a rounded inlet that receives the fuel flow 350 or can be conical inlet. The conical jet 1105A can be at a minimum conical jet diameter D3 of, for example, approximately 0.08 mm, at conical jet outlet 1160 and at a maximum conical jet diameter D4 of, for example, approximately 0.15 mm at the conical jet inlet 1135. The conical jet diameter decreases from the conical jet inlet 1135 to the conical jet outlet 1160. The cone formed by the conical jet 1105A can be at a cone angle of, for example, approximately 8 degrees.
The conical diffusor 1105B has a larger increasing diameter toward the conical diffuser outlet 1136 and allows for more air 345 to be entrained with the fuel 350. The conical diffusor 1105B can be at a maximum conical diffusor diameter D6 of, for example, approximately 0.24 mm, at conical diffusor outlet 1136. The conical diffusor 1105B can be at a minimum conical diffusor diameter D7 at conical diffusor inlet 1136, where D7<D6 and where the conical diffuser diameter increases from the conical diffuser inlet 1137 to the conical diffuser outlet 1136. The cone formed by the conical diffusor 1105B can be at a cone angle of, for example, approximately 25 degrees.
The conical shape of the conical diffuser 1105B permits the laser machining to swivel via outlet 1136 in order to shape the conical diffusor 1105B and conical jet 1105A into the desired configurations. Other types of standard machining (such as, e.g., electrical discharge machining or EDM) may be used to shape the conical jet 1105A and conical diffusor 1105B.
Since the fuel 350 is traveling from the wider diameter D4 at conical jet inlet 1135 to the narrower diameter D3 at conical jet outlet 1160, a high speed movement is applied to the flow of fuel 350 and the swirl, movement of the air 345 from air passages 1115A and 1115B will also entrain air into the fuel flow, leading to a wider plume angle 365 of the plume 360.
The laval nozzle 1215 creates a high speed flow (or increased speed flow) for the air 345 that will be entrained with the fuel 350 that flows along the fuel injection passage 1205. The laval nozzle 1215 includes an inlet opening 1220 of a wide geometric shape opening such as a round opening, rectangular opening, elliptical opening, or other geometric opening. The laval nozzle inlet 1225 can also have conical shape, bell-mouth shape (funnel shape), bottleneck shape, or another suitable geometric shape that reduces the flow restriction on the air 345. In the example of
A narrow passage 1230 is adjacent to the inlet 1225. The narrow passage 1230 is the minimum laval nozzle diameter D8 value for the laval nozzle 1215. As an example, the diameter D8 is approximately 0.08 mm.
A laval nozzle diffusor 1235 is adjacent to the narrow passage 1230. The diffusor 1235 can have a conical shape or other increasing geometric shape that permits diffusion of the air flow 345 from the narrow passage 1230. The diffused air flow 345 flows from the diffusor 1230 to a volume 1242. The volume 1240 could have a suitable geometric shape such as, for example, a cylinder shape. The volume 1242 will have a widest section S1. As an example, the widest section S1 is approximately 0.6 mm.
Within the volume 1242, the air flow 345 mixes with and is entrained into the fuel 350 that flows from the conical jet 1205A. The air/fuel mixture then flows through the conical diffuser 1205B and exits through the conical diffusor outlet 1236. The outlet 1236 will have a diameter of, for example, approximately 0.52 mm.
The conical jet 1205A will have the smallest diameter value at location 1240 where the conical jet 1205A connects to the volume 1242. The use of the laval nozzle 1215, volume 1242, conical jet 1205A, and conical diffusor 1205B allow the improved entrainment of air 345 into the fuel 350, resulting in a broad plume angle 365 for the plume 360 that exits the outlet 1236 or non-homogenous patterns of decreased fuel droplet sizes in the fuel plume 360.
The laval nozzle 1315(1) is connected to the conical jet 1305A(1) and conical diffusor 1305B(1). The laval nozzle 1315(2) is connected to the conical jet 1305A(2) and conical diffusor 1305B(2). The laval nozzle 1315(3) is connected to the conical jet 1305A(3) and conical diffusor 1305B(3). The details of a laval nozzle has been previously described above.
The plume angle 365 would be wider due to air entrainment with the fuel droplets and the compression pressure against the fuel droplets. For example, the plume angel 365 is approximately 25 degrees. More entrainment of air 345 in the fuel results in a wider plume angel 365 for a plume 1406C (and for the other plumes 1406A-1406B).
The injector offset angle 1416 is the angle of a fuel injection passage with respect to an orientation of an injector axis 1420. In
The fuel injection passage 1405A is offset by an injector offset angle 1416 of, e.g., 30 degrees from the injector axis 1420. As a result, the plume 1406A travels in a direction that is substantially along the offset axis 1418.
Similarly, the fuel injection passage 1405C is offset by an injector offset angle from the injector axis 1420. A
The fuel injection passage 1405B has an orientation that is substantially along the injector axis 1420. As a result, the plume 1406B travels in a direction that is substantially along the injector axis 1420.
Embodiments of the invention advantageously provide a broader fuel plume angle which will reduce large air pocket areas in the combustion chamber by filling these large air pocket areas with fuel droplets. In other words, an embodiment of the invention allows the improved entrainment of air into the fuel, resulting in a broad plume angle for the air-fuel mixture that is transmitted to the combustion chamber or/and non-homogenous patterns of decreased fuel droplet sizes for the air-fuel mixture.
The twisted fuel inlets 1505A is formed by, for example, the fuel paths 1505(1)-1505(3) which are separate holes that are drilled through the material that forms the fuel injection passage 1505. The fuel paths 1505(1)-1505(3) may be drilled by, for example, laser drilling or other suitable machining methods. The number of fuel paths may vary in number.
The fuel paths 1505(1), 1505(2), and 1505(3) will have axis lines (center lines) 1510(1), 1510(2), and 1510(3), respectively, as best shown in
The non-parallel fuel flows 225(1)-225(3) will introduce a swirl-like or twist-like (or other disturbance) to the fuel flow in the fuel passage 1505. Therefore, the kinetic energy of the fuel flow through fuel passage 1505 will be higher than the air flow 345 through the air passage 1515. If the fuel 350 through fuel passage 1505 has approximately 2000 bar of potential energy and approximately 700 meters/second of kinetic energy, then the impulse created by the meeting of the fuel flows 350(1)-350(3) and air 345 along the volume 1542 improves air entrainment in the fuel flow. As similarly discussed above, the air entrainment in the fuel flow permits a wider angle 365 in the fuel plume 360 that exits the outlet 1536 and aid in the bursting of fuel in the combustion chamber.
The fuel paths 1705(1)-1705(2) will have the axis lines (center lines) 1710(1)-1710(2), respectively, that are non-parallel (i.e., are skewed, offset, or twisted). Therefore, the non-parallel fuel flows 350(1)-350(2), along the non-parallel fuel paths 1705(1)-1705(2), respectively, introduces a swirl or twist to the fuel flow 350 in order to improve the air entrainment in the fuel flow.
The twin tangential air passages 1715A and 1715B are connected to the fuel injection passage 1705 at a tangential junction, as similarly discussed above. The air passages 1715A and 1715B have inlets 1738A and 1738B, respectively. Each of the inlets 1738A and 1738B has a shape that decreases the flow resistance for the air 345. For example, each of the inlets 1738A and 1738B has a bell-mouth shape as shown in the example of
The air passages 1715A/1715B also provide the air swirl 1780 that provides a twisting movements to the fuel flows 350(1)-350(2). Therefore, the fuel 350 and air 345 will each have a swirl 1780 that improves air entrainment in the fuel 350 and the air entrainment will aid in bursting the fuel plume that exits the conical diffusor 1705B (
The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.
These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.
This application claims a priority to and claims the benefit of U.S. Provisional Application No. 61/275,812. U.S. Provisional Application No. 61/275,812 is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61275812 | Sep 2009 | US |
