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Title:
METHOD AND SYSTEM FOR THE MODIFICATION AND CONTROL OF COMBUSTION
Document Type and Number:
WIPO Patent Application WO/2008/000096
Kind Code:
A1
Abstract:
A method and system for controlling combustion parameters for a fuel air mixture in a combustion chamber is provided. By applying appropriate frequencies, power levels and patterns of acoustic energy to the contents of the combustion chamber, a wide range of desired results can be obtained which, for an engine employing the present invention, can improve power output, reduce fuel consumption and/or reduce undesired emissions. The frequencies, power levels and patterns of acoustic energy applied to the contents of the combustion chamber can be varied according to engine operating conditions, loading, operating speed, fuel condition and a variety of other factors as will be apparent to those of skill in the art.

Inventors:
SCURTU, Petru, R. (1287 Renfield Drive, Burlington, Ontario L7M 4Z5, CA)
CLELAND, Terry, P. (1769 Woodview Avenue, Pickering, Ontario L1V 1L3, CA)
SPICER, Gary, J. (2120 Rathburn Road East, Unit #77Mississauga, Ontario L4W 2S8, CA)
Application Number:
CA2007/001178
Publication Date:
January 03, 2008
Filing Date:
July 03, 2007
Export Citation:
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Assignee:
LITENS AUTOMOTIVE PARTNERSHIP (730 Rowntree Dairy Road, Woodbridge, Ontario L4L 5T9, CA)
SCURTU, Petru, R. (1287 Renfield Drive, Burlington, Ontario L7M 4Z5, CA)
CLELAND, Terry, P. (1769 Woodview Avenue, Pickering, Ontario L1V 1L3, CA)
SPICER, Gary, J. (2120 Rathburn Road East, Unit #77Mississauga, Ontario L4W 2S8, CA)
International Classes:
F02B51/06; B06B1/02; F02B77/00; F02D45/00
Foreign References:
JP2001263115A
US6450154B1
US5992354A
US5027764A
US2454900A
US2737163A
FR2484018A1
Other References:
FERGUSON C.R. ET AL.: 'Internal Combustion Engines Applied Thermosciences', vol. 2ND ED., 2001, JOHN WILEY AND SONS, INC. pages 7 - 8
Attorney, Agent or Firm:
IMAI, Jeffrey, T. et al. (Magna International Inc, 337 Magna DriveAurora, Ontario L4G 7K1, CA)
Download PDF:
Claims:

We claim:

1. A method of controlling combustion of a mixture of fuel and air in a combustion chamber of an engine, comprising: determining the volume of the combustion chamber and the amount of the mixture of fuel and air therein; applying acoustic energy to the mixture of fuel and air in the combustion chamber to alter the combustion characteristics of the mixture, the acoustic energy being applied at a frequency and power level dependent upon the determined volume and amount of the mixture.

2. The method of claim 1 wherein the acoustic energy forms a substantially standing wave in the mixture of fuel and air.

3. The method of claim 2, wherein forming the standing wave provides relatively higher pressure areas to assist in ignition of the fuel air mixture.

4. The method of claim 3 wherein forming the relatively higher pressure areas are timed for optimal ignition.

5. The method of claim 4, wherein forming the relatively higher pressure areas are timed to be located near a point of ignition.

6. The method of claim 5 wherein the acoustic energy is at a frequency of greater than 20 kilohertz.

7. The method of claim 6 wherein the acoustic energy is at a power of between 1 and 300 watts.

8. The method of claim 7 wherein the acoustic energy is at a frequency of about 34.8 kilohertz.

9. The method of claim 1 wherein the acoustic energy forms a moving wave in the mixture of fuel and air.

10. The method of claim 9 wherein the moving wave distributes the mixture of fuel and air in the combustion chamber, more or less evenly, and the pressure of the mixture is substantially constant throughout combustion chamber enabling combustion of the mixture to propagate relatively smoothly outwardly from an ignition point.

11.The method of claim 9 wherein the moving wave is formed for a first period before or after ignition and a standing wave is formed for a second period after or before ignition.

12. The method of claim 10 or 11 wherein the acoustic energy is at a frequency of greater than 20 kilohertz.

13. The method of claim 12 wherein the acoustic energy is at a power of between 1 and 300 watts.

14. The method of claim 1 wherein the acoustic energy is applied from at least two separate transducers.

15. The method of claim 14 wherein the acoustic energy from each transducer is arranged to create an interference pattern in the mixture of fuel and air.

16. A system for controlling combustion of a mixture of fuel and air in a combustion chamber of a diesel engine, comprising: a crankshaft position sensor; an engine control sensor; at least one acoustic transducer operable to apply acoustic energy to the mixture of fuel and air in the combustion chamber; and a control device responsive to outputs from each of the crankshaft position sensor and fuel control sensor to control the transducer to apply acoustic energy to the mixture of fuel and air in a combustion chamber to achieve a desired configuration of combustion.

17. The system of claim 16 wherein the engine control sensor comprises a mass airflow sensor and a throttle plate position sensor.

18. The system of claim 16 wherein said at least one acoustic transducer comprises: at least one electrically driven source of acoustic energy; and a plate in acoustical communication with the source of acoustical energy, the plate comprising a plurality of acoustic horns on one of its surfaces, each of the horns having a mouth diameter, profile and throat length selected to enhance the transfer of acoustic energy from the plate to a fuel air mixture in the combustion chamber.

19. The system of claim 18 wherein all of the plurality of horns have similar mouth diameters, profiles and throat lengths.

20. The system of claim 18 wherein the plurality of horns are arranged into at least two groups, the horns in each group of horns having a selected diameter, profile and throat length which differs from the horns in each other

group.

21.An acoustic transducer comprising: at least one electrically driven source of acoustic energy; and a plate in acoustical communication with the source of acoustical energy, the plate comprising a plurality of acoustic horns on one of its surfaces, each of the horns having a mouth diameter, profile and throat length selected to enhance the transfer of acoustic energy from the plate to a fuel air mixture in the combustion chamber.

22. The acoustic transducer of claim 21 wherein all of the plurality of horns have similar mouth diameters, profiles and throat lengths.

23. The acoustic transducer of claim 21 wherein the plurality of horns are arranged into at least two groups, the horns in each group of horns having a selected diameter, profile and throat length which differs from the horns in each other group.

24. The acoustic transducer of claim 21 wherein the plate is spaced from said source of acoustic energy.

Description:

Method and System For the Modification and Control of Combustion

FIELD OF THE INVENTION

The present invention relates to a system and method for the modification and control of combustion. More specifically, the present invention relates to a method and system for controlling the combustion of a mixture of fuel and air with acoustical energy.

BACKGROUND OF THE INVENTION

Much effort has been, and is being, expended on improving the combustion of mixtures of fuel and air to improve fuel efficiencies and/or to reduce undesired emissions in the exhaust resulting from the combustion.

In particular, much effort has been directed to optimizing combustion in internal combustion engines, both gasoline and diesel engines, to increase their fuel efficiency (to reduce fuel consumption) and to reduce their exhaust emissions.

Many of the issues and problems associated with optimizing combustion in internal combustion engines are discussed in the article "Mastering Combustion" and its associated articles on pages 20 through 32, from the April 2005 issue of R&D Magazine and the contents of these articles are incorporated herein by reference.

To date, combustion optimization in internal combustion engines has primarily concentrated on creating a proper stoichiometric mixture of fuel and air and appropriately arranging that mixture of fuel and air within the combustion chamber by carefully designing the shape of the combustion chamber. Strategies such as employing stratified fuel air charges of richer and leaner mixtures have been successfully employed, as have various swirl or other fuel air mixing and positioning arrangements.

However, all prior art approaches to combustion optimization known to the present inventor have been limited to establishing, adjusting and/or altering

combustion parameters when forming the fuel air mixture and/or when introducing the fuel into the combustion chamber.

It is desired to have a system and method to alter combustion parameters after the fuel air mixture has been introduced into the combustion chamber and/or as combustion is occurring.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a novel system and method of controlling the combustion of a mixture of fuel and air which obviates or mitigates at least one disadvantage of the prior art.

According to a first aspect of the present invention, there is provided a method of controlling combustion of a mixture of fuel and air in a combustion chamber of an engine, comprising: determining the volume of the combustion chamber and the amount of the mixture of fuel and air therein; applying acoustic energy to the mixture of fuel and air in the combustion chamber to alter the combustion characteristics of the mixture, the acoustic energy being applied at a frequency and power level dependent upon the determined volume and amount of the mixture.

According to another aspect of the present invention, there is provided a system for controlling combustion of a mixture of fuel and air in a combustion chamber of a gasoline engine, comprising: a crankshaft position sensor; a mass airflow sensor; a throttle plate position sensor; at least one acoustic transducer operable to apply acoustic energy to the contents of the combustion chamber; and a control device responsive to outputs from the crankshaft position sensor, mass airflow sensor and throttle plate position sensor to control the transducer to apply acoustic energy to the contents of the combustion chamber to achieve a desired configuration of combustion.

According to yet another aspect of the present invention, there is provided a system for controlling combustion of a mixture of fuel and air in a combustion chamber of a diesel engine, comprising: a crankshaft position sensor; a fuel

control position sensor; at least one acoustic transducer operable to apply acoustic energy to the contents of the combustion chamber; and a control device responsive to outputs from the crankshaft position sensor and fuel control position sensor to control the transducer to apply acoustic energy to the contents of the combustion chamber to achieve a desired configuration of combustion.

According to yet another aspect of the present invention, there is provided a transducer for supplying acoustic energy to the combustion chamber of an internal combustion engine, comprising: at least one electrically driven source of acoustic energy; a plate in acoustical communication with the source of acoustical energy, the plate comprising a plurality of acoustic horns on one of its surfaces, each of the horns having a mouth diameter, profile and throat length selected to enhance the transfer of acoustic energy from the plate to a fuel air mixture in the combustion chamber.

The present invention provides a method and system for controlling combustion parameters for a fuel air mixture in a combustion chamber. By applying appropriate frequencies, power levels and patterns of acoustic energy to the contents of the combustion chamber, a wide range of desired results can be obtained which, for an engine employing the present invention, can improve power output, reduce fuel consumption and/or reduce undesired emissions.

The frequencies, power levels and patterns of acoustic energy applied to the contents of the combustion chamber can be varied according to engine operating conditions, loading, operating speed, fuel condition and a variety of other factors as will be apparent to those of skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein:

Figure 1 shows a schematic cross sectional side representation of a cylinder of an internal combustion engine incorporating a transducer of the present invention;

Figure 2 shows a cross section through a prior art combustion chamber of a cylinder in an internal combustion engine;

Figure 3 shows a cross section, taken along line 3-3 in Figure 1 , where the system and method of the present invention has been employed to create a substantially homogeneous distribution of fuel and air in the combustion chamber;

Figure 4 shows the cross section of Figure 3 with a distribution of a fuel air mixture influenced by the application of acoustic energy in a standing wave to create localized regions of increased and decreased pressure;

Figure 5 shows a perspective view of a multi-horn plate used with an acoustic energy transducer of Figure 1 ;

Figure 6 shows a detailed cross section through a cylinder head with the acoutstic energy transducer mounted on a ;

Figure 7 shows a schematic of the control system of the present invention; and

Figure 8 shows a cross section through a cylinder wall incorporating a transducer and a multi-horn plate of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A portion of a gasoline internal combustion engine, with a combustion control system in accordance with the present invention, is indicated generally at 20 in Figure 1. While the following discussion focuses primarily on controlling combustion in internal combustion engines, and in particular reciprocating piston engines and in both diesel and gasoline configurations, the present invention is not so limited and it is contemplated by the inventor that the present invention can be advantageously employed with a much wider range of internal combustion engines.

For example, it is contemplated that the present invention can be advantageously employed with two stroke gasoline engines, gas turbines, Wankel rotary engines and others. Further, while the discussion below focuses

on normally aspirated engines, the present invention can also be advantageously employed with turbocharged or supercharged engines. Also, while only diesel and gasoline fuels are specifically discussed herein, the present invention is not limited to controlling the combustion of these fuels and it is contemplated that the combustion of any fuel in a fuel air mixture can be controlled with the present invention. In particular, the combustion of other liquid fuels such as kerosene, Jet A, Jet B, bio diesel, bunker oils, etc. can be controlled as can the combustion of fluidized solid fuels such as micro pulverized coal, etc.

In the illustrated embodiment, engine 20 includes at least one cylinder 24 in which a piston 28 can move in a reciprocating manner and piston 28 is connected to a crankshaft 32 by a connecting rod 36. The volume within cylinder 24, above piston 28, below a cylinder head 25, serves as a variable volume combustion chamber 38 in which a mixture of air and fuel is combusted to operate engine 20.

Each cylinder 24 further includes at least one inlet valve 40 and at least one exhaust valve 44. The operation of each of inlet valve 40 and exhaust valve 44 is typically controlled via one or more camshafts (not shown) or any other suitable means, as will occur to those of skill in the art.

Engine 20 is a four cycle engine, so inlet valve 40 opens during the intake stroke of piston 28 to admit a mixture of fuel and air to combustion chamber 38, the fuel and air mixture typically being formed in an inlet manifold (not shown) upstream of inlet valve. When the appropriate amount of the fuel air mixture has been admitted to combustion chamber 38, inlet valve 40 is closed and the fuel air mixture is compressed as the volume of combustion chamber 38 is reduced by the upward movement of piston 28 on the compression stroke.

When piston 28 approaches, or passes, the top of its compression stroke (i.e. - the minimum volume of combustion chamber 38), the fuel air mixture is ignited by one or more spark plugs 52 which are electrically fired to ignite and combust the fuel air mixture.

As the fuel air mixture is combusted and the gases in combustion chamber 38 expand, piston 28 is forced down on its power stroke and, after the power stroke of piston 28, exhaust valve 44 opens as piston 28 again moves up cylinder 24 on its exhaust stroke to allow the combustion waste products (exhaust) to exit combustion chamber 38. The cycle then repeats. While this discussion concerns four cycle engines, the present invention is not limited to four cycle engines and can also be advantageously employed with two cycle, Wankel cycle and other engine cycles.

As mentioned above, in conventional gasoline engines much design effort and consideration is employed in the design of combustion chamber 38 and the positioning and operation of inlet valve 40 and exhaust valve 44 in an attempt to optimize the composition, position, temperature and pressure of the mixture of fuel and air in combustion chamber 38 to obtain as homogeneous a distribution of the fuel air mixture as possible when spark plug 52 is fired to ignite the fuel air mixture.

Once ignition has occurred at an ignition point (preferably adjacent spark plug 52), combustion proceeds throughout the combustion chamber as a combustion front expands outward from the ignition point to the edges of the combustion chamber. This moving combustion front results in several undesired combustion characteristics when compared to a more ideal combustion profile wherein ignition would occur at multiple ignition points to reduce the required time for the combustion of the fuel air mixture to be complete. Some prior engine designs have employed two or more spark plugs 52 per cylinder in an attempt to increase the number of ignition points in combustion chamber 38 and, while such systems can perform somewhat better that single ignition point designs, they are still quite limited in their performance.

Figure 2 shows a distribution of the fuel air mixture in a prior art combustion chamber. In this Figure, and in Figures 3 and 4, the stipple patterns are used to indicate the density and pressure of the mixture of fuel and air in the

cylinder and, as will be apparent to those of skill in the art, the individual dots of the stipple are not intended to indicate individual molecules of the fuel air mixture.

As shown in Figure 2, the distribution of the fuel air mixture is not homogenous (as indicated by the irregular spacing of the stipple dots) and regions of increased fuel (richer mixture) and decreased fuel (leaner mixture) occur, as do variations in the pressure of the mixture. These irregularities in the distribution of the fuel air mixture result in less efficient combustion and increased exhaust emissions as the combustion front does not make a smooth expansion.

In the present invention, engine 20 includes at least one ultrasound transducer 56 per cylinder 24, each mounted externally of the combustion chamber 38. In the simplest embodiment, a plurality of transducers are affixed about the outside wall of cylinder 24. Ultrasound transducer 56 can be a piezoelectric element or any other electrically controllable transducer capable of applying acoustic energy to the fuel air mixture in combustion chamber 38. As discussed in more detail below, transducer 56 applies acoustic energy to the cylinder 24, in the ultrasound range, which inturn transfers the acoustic energy to the fuel air mixture in combustion chamber 38 to alter combustion parameters of that mixture to improve the fuel efficiency of engine 20 and/or to reduce undesired exhaust emissions from engine 20.

In the present invention, acoustic energy, generally at ultrasound frequencies of greater than twenty kilohertz, can be applied to the contents of combustion chamber 38 by transducer 56, although it is contemplated that in some circumstances advantageous effects can be obtained at frequencies lower than twenty kilohertz and the use of such lower frequencies is intended to be within the scope of the present invention. For an average sized cylinder, 34.8 kilohertz has been found to produce advantageous results.

In the present invention, the acoustic energy applied to the contents of the

combustion chamber is at medium to high at power levels, in the range from about one watt to about three hundred or more watts, which are sufficient to physically alter the combustion parameters of the fuel air mixture. Such physical alterations can include movement and/or compression and rarefaction of the fuel and air molecules in the mixture. As described below, in the present invention the acoustic energy can be applied at a variety of specific frequencies, power levels and/or configurations to alter the distribution and/or pressure of the mixture of fuel and air in combustion chamber 38 as desired.

For example, by selecting an appropriate frequency and power level, a moving wave can be induced in the fuel air mixture in combustion chamber 38 to create a more substantially homogeneous distribution, as shown in Figure 3, of the fuel air mixture in combustion chamber 38 prior to, or during, combustion of the mixture. As shown in the Figure, the mixture of fuel and air in combustion chamber 38 is distributed, more or less evenly, and the pressure of the mixture is substantially constant throughout combustion chamber 38. Once ignited by spark plug 52, combustion will propagate relatively smoothly outwardly from the ignition point.

By selecting a different frequency and power level, a standing wave can be induced in the fuel air mixture in combustion chamber 38, as shown in Figure 4, wherein one or more bands 60 of increased pressure (as indicated by the decreased spacing between the stipple dots) can be induced in the fuel air mixture.

As is well known by those of skill in the art, the ratio of fuel to air in the mixture in combustion chamber 38 must be higher for ignition to occur than is otherwise required or desired for optimal combustion. Thus, a conventional gasoline engine typically runs with a higher ratio of fuel to air (a richer mixture) than is otherwise desired to ensure that ignition of the mixture can be properly initiated.

As is known, a leaner mixture of fuel and air can be ignited at an

increased pressure than would be the case at a lower pressure. Thus, by establishing a standing wave for a period immediately prior to ignition or firing of spark plug 52, higher pressure areas can be created when needed to assist in ignition of the fuel air mixture. As these higher pressure areas can be created at the optimal time for ignition, pre-ignition (detonation) which might otherwise occur if the fuel air mixture in combustion chamber 38 was generally at the higher pressure level, can be avoided. Thus, engine 20 can be operated under leaner operating conditions than would otherwise be the case, increasing fuel efficiency and reducing exhaust emissions.

Further, by increasing the pressure of the fuel air mixture in bands 60, propagation of the combustion front can be directed along bands 60 to achieve improved propagation throughout combustion chamber 38.

The frequency and power levels required for transducer 56 to create a standing wave in combustion chamber 38 will depend on the volume of combustion chamber 38, and the amount of fuel air mixture in combustion chamber 38. As will be apparent to those of skill in the art, an engine control unit (not shown), such as those used to control ignition timing and fuel injector operation, or any other suitable control device, can determine the volume of combustion chamber 38 from the position of crankshaft 32 and can determine the amount of fuel air mixture in combustion chamber 38 from various known sensors, such as mass airflow sensors and/or throttle plate position sensors. The engine control unit, or other control device, can then provide the necessary electrical signals directly to transducer 56, or to another controller (not shown) for transducer 56, to have transducer 56 apply the correct frequency and/or power level of acoustic energy to combustion camber 38 to create the desired wave.

The present invention is not limited to the use creation of a standing or moving waves in combustion chamber 38 and any desired pattern of acoustic energy can be created in combustion chamber 38. For example, a moving wave can be induced in combustion chamber 38 for a period prior to the point when

ignition of the fuel air mixture occurs and a standing wave can be applied for a period after ignition to direct the combustion front or alter other parameters of the combustion of the fuel and air mixture. Other combinations or patterns of waves can be applied, as desired, to alter the parameters of the combustion of the fuel air mixture as desired.

It is also contemplated that two or more transducers 56 can be provided for each cylinder 24, each of which can be driven or excited at different frequencies. In such a case, various interference patterns can be imposed on the fuel air mixture to achieve a variety of potentially desirable effects such as inducing a grid or other arrangement of pressure differentials in the fuel air mixture or directing the fuel air mixture away from the walls of cylinder 24, etc.

As mentioned above, the present invention can also be employed with diesel engines. As is known, diesel engines do not employ spark plugs to ignite their fuel air mixture and instead directly inject the fuel into combustion chamber 38 once a desired level of compression of the air therein has been achieved. The heat generated by the compression of the contents of combustion chamber 38 results in the fuel air mixture igniting and combusting.

By applying acoustic energy from transducer 56, various parameters of the ignition and combustion of the mixture of diesel fuel and air in combustion chamber 38 can be achieved. In particular, it is contemplated that extremely lean mixtures, such as those proposed in Homogenous Charge Compression Ignition (HCCI) systems can be subjected to acoustic energy to create localized areas of higher and lower pressures to inhibit the undesired simultaneous ignition of the entire contents of combustion chamber 38. The induced higher pressure regions in the contents of combustion chamber 38 would ignite first, followed by the ignition of the induced lower pressure regions.

With diesel engines, or other direct injection engines, it is contemplated that transducer 56 can be part of the fuel injector. In such a case, transducer 56 can be used to better atomize the fuel as it is injected and can then be used to

apply acoustic energy to combustion chamber 38, as described above. However, it is also contemplated that in many circumstances at least two transducers 56 will be employed with each cylinder 24 and that one of these two transducers 56 can be part of the injector while the other transducer 56 will be separate from the injector.

It is contemplated that for gasoline or diesel engines, in addition to, or instead of, having transducers 56 as part of the fuel injector, transducers 56 can be located on or connected to either or both of inlet valve 40 or exhaust valve 44, a wall of cylinder 24, the head gasket between the cylinder block and the head of cylinder 24, the inlet or exhaust manifold of engine 20, etc.

In particular, a transducer 56" for a cylinder 24 can be an acoustic lens transducer which is included as a component in the head gasket of engine 20 or otherwise located between the cylinder block and the cylinder head. In such a case, the acoustic lens transducer 56" can be annular as shown in Figure 9 and can act as a seal between the top of cylinder 24 and the head on engine 20. Transducer 56" comprises an inner annular ring 71 and an outer annular ring 73. A piezoelectric element or elements 75 is sandwiched between the inner annular ring 71 and outer annular ring 73. The inner diameter of the inner annular ring 71 is the same as the cylinder 24, with which the transducer 56" is to be used.

By locating transducer 56" in this manner, electrical connections to the transducer can be routed through the head gasket and transducer 56" can be in direct (albeit limited) contact with the interior of combustion chamber 38.

Further, by providing transducers 56" in the head gasket, it is contemplated that existing engine designs can be retrofit with the present invention without requiring redesign or re-machining merely by providing the transducer equipped head gasket and providing the necessary electrical control and sensor devices.

It is also contemplated that, to achieve the necessary power levels of

acoustic energy in combustion chamber 38, a stepped plate transducer as shown in Figure 6, may be preferred but the present invention can be employed with any other suitable transducer construction or configuration as will occur to those of skill in the art. In this Figure, the transducer 56' comprises a pair of annular rings 91 , 93 that are mounted on opposite sides of piezoelectric elements 95. Bolt 97 urges or sandwiches the piezoelectric elements 95 together. Plate 81 has a cylindrical core 85 that has a threaded portion 99 that receives and mounts transducer 56'. The plate 81 is affixed to the cylinder head 25 at convenient locations via bolts 83. The core 85 has a stem 87 that is affixed to the cylinder head 25 by screw 89. Plate 81 is sized and configured such that plate 81 will be at a node of the wave generated by the transducer 56'. Additionally, plate 81 is spaced from the cylinder head so that the cylinder head 25 is also at a maximum or crest of the wave being generated. Thus, plate 81 is relatively stationary in supporting transducer 56'. As transducer 56' vibrates, the stem 87 transfers this vibration to the cylinder head 25, which will then transfer the vibration to the combustion chamber 38. The plate 81 is not limited to being oriented parallel to the cylinder head 25. Plate 81 may be oriented at an angle relative to the cylinder head 25 to enable the transducer 56' to be mounted amongst the other engine elements, such an valves, spark plugs, fuel injectors etc. that are also normally located there.

The large differences between the density of the metal cylinder and cylinder head and the density of the fuel air mixture can make the transfer of acoustic energy from the transducer 56 to the fuel air mixture difficult to achieve. In a presently preferred embodiment, transducer 56' includes a multi-horn plate 100, as illustrated in Figure 5, which transducer 56' drives and which serves as an impedance matching radiation source of acoustic energy. As illustrated in Figure 8, the multi-horn plate 100 is mounted on an inside surface of the cylinder 24, preferably on the inside surface of the cylinder head 25. The multi-horn plate 100 is spaced from the cylinder head 25 by a small gap, preferably in the 40 to

50 micron range, depending on the size and type of the cylinder 24.

As is known, the lower cut-off frequency of a horn is determined by the profile of the horn while the higher cut off frequency of the horn is determined by the total curvature of the radiated wave front at the mouth of the horn. For a given throat diameter and mouth diameter, the bandwidth of a given horn increases with the length of the horn.

While good results can be obtained with a transducer driving a single, large horn, the design of internal combustion engines typically prevents the use of such a horn within the confines of an engine. Instead, the present inventors have designed multi-horn plate 100 which features a plurality of small horns 104 on the surface of multi-horn plate 100 facing into the combustion chamber. Each horn 104 can be appropriately designed to efficiently transfer acoustic energy from multi-horn plate 100 to the fuel air mixture in the combustion chamber, when multi-horn plate 100 is driven by transducer 56. In use, each horn 104 transfers acoustic energy to the fuel air mixture immediately adjacent its mouth.

It is contemplated that groups of horns 104 of multi-horn plate 100 can be created with different diameters and profiles from other groups of horns 104 such that multi-horn plate 100 can efficiently transfer acoustic energy to fuel air mixtures which are at different densities and/or pressures, such as when the engine is operating at different speeds and/or load conditions. In such a case, one group of horns 104 which are optimized for a first set of pressure and/or density conditions can be arranged about multi-horn plate 100 plate and a second group of horns 104 which are optimized for another set pressure and/or density conditions can be also arranged about multi-horn plate 100. As should be apparent to those of skilled in the art, multi-horn plate 100 can include more than two groups of such horns 104, if desired.

It is also contemplated that multi-horn plate 100 can be driven by more than one transducer 56, if desired.

As shown in the Figure, multi-horn plate 100 can include apertures 108 to

allow inlet or exhaust valves to open, apertures 112 for fuel injectors and/or spark plugs to access the cylinder, etc.

Referring to Figure 7, it is also contemplated that transducer 56, 56' and 56" can be employed as both the above-described combustion modification system and as a sensor to determine various parameters of combustion within cylinder 24. Specifically, if transducer 56, 56' and 56" employs an element, such as a piezoelectric element or similar device, to convert electrical energy to acoustic energy, such elements typically also operate to convert acoustical energy into electrical energy. Accordingly, transducer 56, 56" and 56" can provide an electrical signal to a control device 59, such as an engine control unit, and this signal can provide useful information, such as pressure changes, amplitudes, combustion timing, etc., regarding the combustion of the fuel air mixture with each cylinder 24. This signal can be brought by a feedback loop to the control device to modify the parameters of the ultrasonic wave in terms of power, amplitude, and/or frequency. In such a way the combustion process can be closely monitored and kept under control towards the optimum.

Further, it is thus possible to burn in the same engine different types of fuels, with different caloric capacities. For example diesel, gasoline and other mineral fuels, or canola and other bio fuels could be burned in the same engine. The engine can be preprogrammed to operate with a randomly picked fuel and initiates a sequence of combustion. The transducer 56, 56' and 56" senses the pressure wave produced by the combustion. The control device will vary the parameters around this combustion pressure point, targeting the path towards the optimal function of the engine to produce maximum output power at minimum emissions.

It is further contemplated that multi-horn plate 100 will assist by effectively amplifying the signals provided by transducer 56, 56' and 56".

Thus, in addition to the above-mentioned known engine control sensors 61 , such as the mass airflow sensors 63 and throttle plate position sensors 65,

the present invention can also employ signals from transducer 56, 56' and 56" to appropriately control combustion in cylinder 24.

As should now be apparent to those of skill in the art, the present invention provides a method and system for controlling combustion parameters for a fuel air mixture in a combustion chamber. By applying appropriate frequencies, power levels and patterns of acoustic energy to the contents of the combustion chamber, a wide range of desired results can be obtained which, for an engine employing the present invention, can improve power output, reduce fuel consumption and/or reduce undesired emissions.

The frequencies, power levels and patterns of acoustic energy applied to the contents of the combustion chamber can be varied according to engine operating conditions, loading, operating speed, fuel condition and a variety of other factors as will be apparent to those of skill in the art. Compromises in the design of the combustion chamber, which previously required sacrifices under some operating conditions to achieve desired performance under other operating conditions can be mitigated, or avoided, as combustion parameters for the fuel air mixture in the combustion chamber can be varied with the acoustic transducers of the present invention.

The above-described embodiments of the invention are intended to be examples of the present invention and alterations and modifications may be effected thereto, by those of skill in the art, without departing from the scope of the invention which is defined solely by the claims appended hereto.