IGNITER FOR INTERNAL COMBUSTION ENGINES OPERATING OVER A WIDE RANGE OF AIR FUEL RATIOS
An igniter for ignition over a wide air/fuel ratio range is disclosed. The igniter includes an igniter body including an internal cavity disposed substantially within the igniter body, an internal spark gap disposed substantially within the internal cavity, an external spark gap disposed substantially on an exposed surface of the igniter body, and a fuel charge delivery system for delivering a fuel charge to the internal cavity. A method for compression-igniting an air/fuel mixture in a cylinder of an internal combustion engine is also disclosed. The method comprises introducing a substantially homogeneous charge of a first air/fuel mixture into a cylinder of the internal combustion engine during an intake stroke, compressing the substantially homogeneous charge of the first air/fuel mixture in the cylinder of the internal combustion engine during a compression stroke, and combusting the substantially homogeneous charge of the first air/fuel mixture in the cylinder of the internal combustion engine during a power stroke by injecting partially combusted products of a second air/fuel mixture into the cylinder, with the first air/fuel mixture having a substantially higher ratio, by weight, of air to fuel and the second air/fuel mixture.
This patent application is a continuation-in-part of U.S. patent application Ser. No. 10/451,492, filed on Dec. 23, 2003, which claimed priority to a PCT International Patent Application PCT/US01/28114 in the name of Savage Enterprises, Inc., a United States national corporation and resident, and Applicant for all countries except the United States, and Harold E. Durling, a United States resident and citizen, Applicant for the United States only, on Sep. 7, 2001, designating all countries and claiming priority to U.S. Provisional Patent Application Ser. No. 60/230,982, filed Sep. 7, 2000.
TECHNICAL FIELDThe present invention relates generally to an igniter for use in internal combustion engines. More particularly, the invention relates to an internal combustion igniter, which permits the engine to be operated in a “spark-ignited” mode of operation (with a relatively rich fuel to air ratio) during periods of relatively heavy load and in a diesel mode of operation (with a relatively lean fuel to air ratio) during periods of relatively light load.
BACKGROUNDInternal combustion engines (i.e., those having an intake stroke, a compression stroke, a power stroke, and an exhaust stroke, either as separate strokes (four-stroke) or combined (two-stroke) events) may be divided into two general types: spark-ignited and compression-ignited (e.g., diesel).
Spark-ignited engines and compression-ignited engines each have distinct advantages and disadvantages. For example, as versus compression-ignited engines, spark-ignited engines are generally less expensive to produce, have a greater power density (i.e., horsepower produced per volume of cylinder displacement), and are usually supplied with stoichiometric air/fuel ratios that produce relatively low levels of pollutant emissions. The pollutants that are produced by spark-ignited engines run with stoichiometric air/fuel ratios can also be further reduced to currently acceptable levels by utilizing the post-combustion catalytic converter technology available today.
However, the stoichiometric air/fuel ratios required by spark-ignited engines are generally much richer as compared to the air/fuel ratios utilized in compression-ignited (e.g., diesel) engines. Whereas a spark-ignited engine may run on an air/fuel ratio in the ratio of 20:1, a compression-ignited engine may utilize a much higher air/fuel ratio in the range of 40:1 or 50:1. Therefore, compression-ignited engines generally exhibit better fuel economy.
Compression-ignited engines, which run on such lean air/fuel mixtures and do not operate nearly as close to stoichiometric conditions as spark-ignited engines, tend to produce a higher rate of undesirable emission pollutants. Moreover, the emission pollutants that are produced by compression-ignited engines are not nearly as amenable to treatment by the post-combustion catalytic technology currently available, as are the pollutants produced by spark-ignited engines. Chief among the pollutants produced by combustion-ignition engines are nitrogen-containing compounds (i.e., NOX). Such nitrogen-containing compounds result, at least in part, from the high temperatures produced during compression-ignition. Soot is another pollutant produced in greater quantities during combustion-ignition, and arises primarily from the manner in which fuel droplets sprayed into the hot compressed air burn.
Additionally, as noted above, compression-ignition engines tend to have a significantly lower “power density” as compared to spark-ignited engines. For example, while a high performance spark-ignited engine may produce in the range of 60 horsepower per liter of engine displacement, a compression-ignited engine may produce only in the range of about 10 horsepower per liter of engine displacement. A need exists for improvements.
SUMMARY OF THE DISCLOSUREAn igniter for an internal combustion engine operating over a substantially wide range of air/fuel ratios, the igniter including an igniter body. The igniter body further includes an internal cavity disposed within the igniter body, an internal spark gap disposed within the internal cavity and an external spark gap disposed substantially on an exposed surface of the igniter body. The igniter also includes a fuel charge delivery system for delivering a fuel charge to the internal cavity.
A method for operating an internal combustion engine including determining a load threshold within a load range of the internal combustion engine, operating the internal combustion engine in a spark-ignited mode of operation when the determined load threshold is exceeded, operating the internal combustion engine in a homogeneous-charge compression-ignited mode of operation when the determined load threshold is not attained. The homogeneous-charge compression-ignited mode of operation further includes introducing a substantially homogeneous charge of an air/fuel mixture into a cylinder of the internal combustion engine during an intake stroke, compressing the substantially homogeneous charge of the air/fuel mixture in the cylinder of the internal combustion engine during a compression stroke, and combusting the substantially homogeneous charge of the air/fuel mixture in the cylinder of the internal combustion engine during a power stroke by injecting active radicals of combustion in to the cylinder.
Another embodiment is directed to a turbine engine arrangement comprising a turbine engine body. The turbine engine body defines an upstream portion and a downstream portion. A compression section is located proximate the upstream portion. A combustor is operable to receive a combustion section fuel/air mixture to be ignited into a stationary flamefront to deliver pressurized downstream heated products of combustion. The combustion section has a wall structure defining an igniter aperture. An exhaust section is located downstream from the combustion section for receiving and passing the heated products of combustion out of the turbine engine body. An igniter is disposed proximate the igniter aperture. The igniter comprises an igniter body defining an ignition prechamber in gaseous communication with the combustion section via a port. The igniter is configured to ignite an air-fuel mixture within the ignition prechamber and to project a jet of flame into the combustion section. In this way, the jet of flame reliably lights the flamefront and reliably relights the flamefront under a flameout condition.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to
In the example embodiment shown, fuel or chemical charge delivery system 16 is a conventional liquid fuel injection nozzle (described more fully below), which is supplied with a fuel or chemical mixture through a delivery conduit 22 that also extends along central axis 20. Delivery conduit 22 passes centrally through a secondary cylindrical insulator member 24, which mates into and is positioned adjacent primary cylindrical insulator member 14. A first jam nut 26 threadingly engages shell 12, through threads 28, and contacts a shoulder 102 of primary cylindrical insulator member 14 to retain it in place against member shell 12. Second cylindrical insulator member 24 is retained through the provision of a second jam nut 30, which threadingly engages first jam nut 26 through threads 32.
The above description of construction details relating to the first and second insulator members 14 and 24, respectively, and the first and second jam nuts 26 and 30, respectively, apply to a prototypical model of igniter 10 presently constructed. One of skill in the art will appreciate that for manufacturability purposes, a mass-produced igniter 10 could employ a single cylindrical insulator member and could also dispense with the jam nuts 26 and 30, respectively, employing instead a crimping of the shell 12 to retain such single cylindrical insulator member in place.
In the example embodiment shown, a lower end 104 of the fuel charge delivery system 16 is received within the interior diameter of a tapering cylinder portion 34 of first electrode member 18, which has a wider upper end portion for seating the fuel charge delivery system 16, and a narrower lower end portion from which rod-shaped central electrode 18 projects downward. Surrounding central electrode 18 and extending downward from tapering cylindrical portion 34 of member first electrode 18, the interior of the igniter is provided with an internal cavity 36, which terminates in an outwardly opening orifice 38. Internal cavity 36 is bounded by primary cylindrical insulator 14, which has an upper substantially cylindrical sidewall portion 40, a lower substantially cylindrical sidewall portion 42, and a tapering sidewall portion 44 extending therebetween.
In the example embodiment shown, an intermediate electrode 46 including a conducting material extends upwardly from orifice 38 to a point proximate the tip of central electrode 18. Preferably, intermediate electrode 46 conforms substantially to the shape of and closely contacts the sidewall portions 40, 42, and 44. More preferably, the intermediate electrode 46 is provided in the form of a coating which overlays the sidewall portions 40, 42, and 44. The coating preferably includes a catalyst to promote rapid combustion of a fuel charge delivered to and combusted within internal cavity 36. Examples of catalysts are platinum and platinum-containing substances and compounds.
Igniter 10 is mounted in a cylinder head 48 and projects through cylinder head 48 (shown in partial view) into a cylinder of an internal combustion engine 50. Igniter 10 engages cylinder head 48 through the provision of interlocking threads 52. In the example embodiment shown in
To initiate combustion, a first voltage potential is applied to first electrode 18, communicated to first electrode 18 from an ignition system (not shown) attachment point 80 on exposed portion of the delivery conduit 22, while shell 12 of igniter 10 is maintained at a reference voltage potential. Preferably, the reference voltage at shell 12 is maintained at ground voltage, and an ignition voltage is applied to first electrode 18. More preferably, delivery conduit 22, outer housing 54 of fuel charge delivery system 16, and tapering cylindrical portion 34 of member first electrode 18, all connect electrically, in series with engine ignition system contact point 80 to the arcing tip of first electrode 18 and form, together, first terminal of the igniter 10. With the first and reference terminals at differing voltage potentials, two separate spark gaps are formed: an internal spark gap 66 between the first electrode 18 and the intermediate electrode 46 and an external spark gap 68 formed between intermediate electrode 46 and the reference electrode shell 12. Internal spark gap 66 is located within cavity 36, while external spark gap 68 is disposed substantially adjacent external surface of the lower tip of cylindrical insulator 14 of igniter 10 and found within the volume of cylinder 50. Internal spark gap 66 and external spark gap 68 are, in the embodiment shown, each of annular shape and are electrically disposed in series with one another.
When, as shown in the example embodiment of
An advantage of the example embodiment shown is that igniter 10 permits an internal combustion engine to be operated in a “spark-ignited” mode of operation (with a relatively rich fuel to air ratio) during periods of relatively heavy load and in a diesel mode of operation (with a relatively lean fuel to air ratio) during periods of relatively light load. When operating in a spark-ignited mode of operation, fuel charge delivery system 16 is not actuated and, therefore, the only combustible mixture delivered to the cylinder 50 is an air/fuel mixture delivered on the intake stroke in a conventional manner, e.g., through a fuel injection or carburetion system. For example, an example of a conventional intake port 70 and a conventional injection/carburetion system 72, as shown in
Preliminary results by the applicants have indicated that the upper limit of the air to fuel ratio (by weight) achievable by this spark-ignited mode of operation is on the order of about 20:1. Leaner mixtures than this approximate 20:1 ratio of air to fuel tend to not ignite sufficiently or not ignite at all. However, leaner mixtures (e.g., above 20:1 of air/fuel) offer the possibility of achieving more efficient fuel consumption. Accordingly, the inventive igniter 10 can additionally be operated in a compression-ignition mode of operation, which preliminary results have indicated permits achieving air/fuel ratios on the order of about 40:1 or even perhaps 50:1.
In the compression-ignition mode of operation, a well-dispersed and relatively lean air/fuel mixture (e.g., on the order of about 40:1 to about 50:1) is delivered to cylinder 50 during the intake stroke, and some of this relatively lean air/fuel mixture is forced into internal chamber 36 of igniter 10 during the compression stroke. At or just before ignition, a small charge of a relatively rich air/fuel mixture is delivered by fuel charge delivery system 16 to internal cavity 36 and adjacent internal spark gap 66. When the elevated ignition voltage is applied to central electrode 18, internal spark gap 66 and external spark gap 68 again fire in series, on the order of microseconds apart. The charge delivered by fuel charge delivery system 16 to internal cavity 36, together with the relatively lean mixture forced into internal cavity 36, combine into a relatively rich mixture, and are ignited by the annular spark formed between central electrode 18 and internal electrode 44. A torch jet is thereby created, which ejects partially combusted products through orifice 38. Such partially combusted products are dispersed within cylinder 50 and ignite the already compressed and relatively lean main charge therein, resulting in a rapid and thorough combustion of the main charge. The resulting combustion of the main charge results primarily from compression but is triggered by the dispersion throughout the main charge of the partially combusted products emitted from internal cavity 36. An advantage of this method is that an engine using igniter 10 under a light load accomplishes homogeneous compression ignition of lean air/fuel ratios by introducing charged radicals, not limited to the form of a flame, but also being heated above ambient operating conditions, into the cylinder. One of skill in the art will appreciate that, optimally, igniter 10 is timed to fire when the state of compression is optimum for lean, fuel-efficient, compression ignition, for example, by controlling the timing of compression ignition in a homogeneous air/fuel mixture by “seeding” cylinder 50 with active chemical radicals-produced on demand by igniter 10. An advantage of this method of engine operation is that ignition is not limited to initiation only by a spark or only by compression, but rather by allowing the engine to choose spark and seeded compression ignition, depending on load at which the engine is operating.
This fuel/air mixture is provided to an igniter 160 via a sealed cable 162. The igniter 160 may be implemented, for example, as the igniter 10 of
When activated, the igniter 160 ignites the fuel/air mixture within the ignition prechamber and projects a jet of flame into the combustor within the combustion chamber 172. This jet of flame reliably lights a stationary flamefront 174 to deliver downstream heated products of combustion. Should a flameout condition occur the jet of flame can be manually or automatically activated to reliably relight the flamefront. The igniter 160 is capable of firing a jet rapidly, for example, 5-10 times per second. It is anticipated that an engine with a flameout could be re-ignited in a second or two after flame-out, rather than requiring the pilot to place the aircraft into a dive to get the compressor turning and help restart the engine.
The heated products of combustion are received by an exhaust section (not shown in
In other types of turbine engines, the turbine section defines an rotating wheel of turbine blades and an exhaust stack through which the heated products of combustion are passed out of the turbine engine body. A turbine wheel shaft located in the turbine section is rotatable by the heated products of combustion. The turbine shaft is coupled to the upstream compressor and may also be coupled to any of a number of structures for producing movement. For example, the turbine can be coupled to an aircraft propeller for driving the propeller in a rotational manner. Alternatively, the turbine can be coupled to an industrial power shaft for rotating a mechanism that has an industrial application, such as generators or pumps. As another alternative, the turbine can be configured to propel a ground vehicle or a water vehicle.
An ignition control system 196 controls the operation of the charging solenoid 186, the firing solenoid 190, and the fuel solenoid 194. When the ignition control system 196 actuates the firing solenoid 190 and the fuel solenoid 194, a compressed air charge and a fuel charge are delivered from the storage chamber 188 and the engine fuel system 192, respectively, into a mixing chamber 198 to form a fuel/air mixture.
This mixing chamber 198 is directly connected to an igniter 200. The igniter 200 may be implemented, for example, as the igniter 10 of
When activated, the igniter 200 ignites the fuel/air mixture within the ignition prechamber and projects a jet of flame into the combustion chamber 208. This jet of flame reliably lights a stationary flamefront 210 to deliver downstream heated products of combustion. Should a flameout condition occur, the jet of flame can be manually or automatically reactivated to reliably relight the flamefront.
The heated products of combustion are received by an exhaust section (not shown in
In other types of turbine engines, the turbine section defines a rotating shaft with turbine blades on a wheel and an exhaust stack through which the heated products of combustion are passed out of the turbine engine body. A turbine shaft wheel is rotated by the heated products of combustion expanding through multiple stages of turbine blades. The turbine shaft is coupled to the upstream compressor and may also be coupled to any of a number of structures for producing movement. For example, the turbine can be coupled to an aircraft propeller for driving the propeller in a rotational manner. Alternatively, the turbine can be coupled to an industrial power shaft for rotating a mechanism that has an industrial application, such as generators or pumps. As another alternative, the turbine can be configured to propel a ground vehicle or a water vehicle.
While the present invention has been disclosed by way of a detailed description of a number of particularly preferred embodiments, it will be clear to those of ordinary skill that the art that various substitutions of equivalents can be affected without departing from either the spirit or scope of the invention as set forth in the appended claims.
It will be understood by those who practice the embodiments described herein and those skilled in the art that various modifications and improvements may be made without departing from the spirit and scope of the disclosed embodiments. Accordingly, the scope of protection afforded is to be determined solely by the claims and by the breadth of interpretation allowed by law.
Claims
1. A turbine engine arrangement comprising:
- a turbine engine body defining an upstream portion and a downstream portion, a compression section proximate the upstream portion, a combustor operable to receive a combustion section fuel/air mixture to be ignited into a stationary flamefront to deliver pressurized downstream heated products of combustion, the combustion section having a wall structure defining an igniter aperture, and an exhaust section downstream from the combustion section for receiving and passing the heated products of combustion out of the turbine engine body; and
- an igniter disposed proximate the igniter aperture, the igniter comprising an igniter body defining an ignition prechamber in gaseous communication with the combustion section via a port to receive an igniter fuel mixture, the igniter being configured to ignite the igniter fuel mixture within the ignition prechamber and to project a jet of flame into the combustion section,
- whereby the jet of flame reliably lights the flamefront and reliably relights the flamefront under a flameout condition.
2. The turbine engine arrangement of claim 1, wherein the exhaust section comprises an expansion chamber downstream from the combustion section, the expansion chamber defining a jet engine output port that provides a thrust force in an upstream direction in response to the heated products of combustion passing out of the turbine engine body.
3. The turbine engine arrangement of claim 1, wherein the exhaust section comprises a turbine section downstream from the combustion section, the turbine section defining an exhaust nozzle through which the expanding heated products of combustion are passed out of the turbine engine body.
4. The turbine engine arrangement of claim 3, further comprising a turbine located in the turbine section, the turbine being rotatable by the expanding heated products of combustion passing through the turbine section.
5. The turbine engine arrangement of claim 4, wherein the turbine is coupled to an aircraft propeller for driving the propeller in a rotational manner.
6. The turbine engine arrangement of claim 4, wherein the turbine is configured to propel a ground vehicle.
7. The turbine engine arrangement of claim 4, wherein the turbine is configured to propel a water vehicle.
8. The turbine engine arrangement of claim 4, wherein the turbine is coupled to an industrial power shaft for rotating a mechanism having an industrial application.
9. The turbine engine arrangement of claim 8, wherein the mechanism having an industrial application comprises at least one of a pump and an electrical generator.
10. The turbine engine arrangement of claim 1, wherein the igniter comprises an igniter fuel mixture delivery arrangement configured to, when actuated, deliver an igniter fuel mixture into the igniter from an external source.
11. The turbine engine arrangement of claim 10, wherein the igniter comprises an electrode arrangement disposed within the igniter body and defining an internal spark gap, the electrode arrangement being configured to, when actuated, generate a spark across the internal spark gap to ignite the igniter fuel mixture to generate the jet of flame, whereby the jet of flame is projected from the ignition prechamber into the combustion section.
12. The turbine engine arrangement of claim 11, wherein the electrode arrangement comprises a first inner electrode and a second inner electrode.
13. The turbine engine arrangement of claim 11, further comprising an electrode shell disposed proximate an outer surface of the igniter body and defining an external spark gap.
14. The turbine engine arrangement of claim 13, further comprising a capacitor coupled to the electrode arrangement to cause the internal spark gap and the external spark gap to fire sequentially.
15. The turbine engine arrangement of claim 11, wherein the electrode arrangement is disposed within the igniter body proximate the ignition prechamber.
16. The turbine engine arrangement of claim 11, wherein the electrode arrangement is disposed within the igniter body proximate the port.
17. The turbine engine arrangement of claim 10, further comprising a fuel and air storage module operatively coupled to the igniter fuel mixture delivery arrangement and configured to provide selectively and under pressure the igniter fuel mixture to the igniter fuel mixture delivery arrangement, the pressure actuating the igniter fuel mixture delivery arrangement to provide the igniter fuel mixture to the ignition prechamber.
18. The turbine engine arrangement of claim 17, further comprising a solenoid operatively coupled to the fuel storage module and configured to provide selectively the igniter fuel mixture to the fuel storage module.
19. The turbine engine arrangement of claim 10, further comprising an engine control subsystem operatively coupled to the igniter fuel mixture delivery arrangement and configured to control the igniter fuel mixture delivery arrangement to provide under pressure the igniter fuel mixture to the igniter fuel mixture delivery arrangement.
20. The turbine engine arrangement of claim 19, further comprising a voltage source in electrical communication with the engine control subsystem and configurable to cause the igniter to ignite the igniter fuel mixture.
21. The turbine engine arrangement of claim 10, wherein the igniter fuel mixture delivery arrangement facilitates pulsed delivery of the igniter fuel mixture, the igniter fuel mixture delivery arrangement comprising:
- a delivery conduit to receive the igniter fuel mixture;
- a valve arrangement operatively coupled to the delivery conduit and configured to open when the delivery conduit receives the igniter fuel mixture; and
- a closure arrangement operatively coupled to the valve arrangement and configured to maintain the valve arrangement in a closed position when the delivery conduit does not receive the igniter fuel mixture.
22. The turbine engine arrangement of claim 21, wherein the closure arrangement comprises a spring.
23. The turbine engine arrangement of claim 10, wherein the igniter fuel mixture delivery arrangement facilitates continuous delivery of the igniter fuel mixture, the igniter fuel mixture delivery arrangement comprising:
- a delivery conduit to receive the igniter fuel mixture; and
- a flame regulation arrangement to prevent a jet of flame from moving into the delivery conduit.
24. The turbine engine arrangement of claim 23, wherein the flame regulation arrangement comprises a flame arrestor.
25. The turbine engine arrangement of claim 1, wherein the igniter fuel mixture comprises at least one of a gaseous fuel and a liquid fuel in combination with at least one of air and oxygen.
26. The turbine engine arrangement of claim 1, further comprising means for evacuating the heated products of combustion from the ignition prechamber.
27. The turbine engine arrangement of claim 1, further comprising an afterburner engine arrangement, the afterburner engine arrangement comprising an afterburner igniter, the afterburner igniter comprising an afterburner fuel mixture delivery arrangement configured to, when actuated, deliver an afterburner fuel mixture into the afterburner igniter from an external source, the afterburner igniter configured to ignite the afterburner fuel mixture and to project a jet of flame into an afterburner chamber, whereby the jet of flame reliably lights the afterburner flame.
Type: Application
Filed: Apr 4, 2006
Publication Date: Feb 1, 2007
Inventors: Harold E. Durling (Elsie, MI), Steven Kensinger (Burnsville, MN), Bradley Dennis (Fridley, MN)
Application Number: 11/278,597
International Classification: F02C 7/264 (20060101);