CA1077575A - System for improving combustion in an internal combustion engine - Google Patents
System for improving combustion in an internal combustion engineInfo
- Publication number
- CA1077575A CA1077575A CA263,385A CA263385A CA1077575A CA 1077575 A CA1077575 A CA 1077575A CA 263385 A CA263385 A CA 263385A CA 1077575 A CA1077575 A CA 1077575A
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- CA
- Canada
- Prior art keywords
- combustion
- combustion chamber
- energy
- mode
- chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
- F02P23/00—Other ignition
- F02P23/04—Other physical ignition means, e.g. using laser rays
- F02P23/045—Other physical ignition means, e.g. using laser rays using electromagnetic microwaves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
- F02P23/00—Other ignition
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Ignition Installations For Internal Combustion Engines (AREA)
- Combustion Methods Of Internal-Combustion Engines (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A technique for increasing the efficiency, and for decreasing the exhaust emissions, of an internal combustion type engine in which rf energy is generated at a frequency which both (a) is suitable for coupling the energy to a com-busting plasma air-fuel mixture (preferably at a plasma frequency) and (b) excites at least one resonant mode of the engine's combustion chamber; so as to enhance both pre-combus-tion conditioning of the mixture and combustion reactions.
A technique for increasing the efficiency, and for decreasing the exhaust emissions, of an internal combustion type engine in which rf energy is generated at a frequency which both (a) is suitable for coupling the energy to a com-busting plasma air-fuel mixture (preferably at a plasma frequency) and (b) excites at least one resonant mode of the engine's combustion chamber; so as to enhance both pre-combus-tion conditioning of the mixture and combustion reactions.
Description
~77575 1 This invention pertains generally to apparatus and a method for increasing efficiency and/or decreasing exhaust emissions of an internal combustion engine.
The concern over air pollution and the dwindling of petroleum resources has resulted in legislation which has caused a shif~ in emphasis from powerful, high compression engines to small, low compression ones. As the degree of pollution which an automobile introduces into the air is measured in parts per mile, a smaller, lower compression engine, burning a leaner mixture (i.e., a higher ratio of air to fuel) can more readily satisfy the pollution requirements.
It is known on the one hand that the level of C0 (carbon monoxide) produced by the internal combustion engina decreases as the air-fuel ratio is increased, and cc)ntinues to decroa~e beyond the "chemlcally ideal" ratlo of 1~.7, and the decrease extends to the "lean limit", i.e., the limit at which flame speed drops to zero and at which the air-fuel mixture does not ordinarily ignite. The production of N0x (oxides of nitrogen), on the other hand, is most sensitive to the time at which the spark is fired ~given in degrees before top dead center, BTDC). The production of N0x in parts per mile, jumps from approximately 1,000 to 3,000 parts when the spark timing is advanced over a 20 range. In order to reduce carbon monoxide, oxides of nitrogen and also other hydrocarbons, therefore, one must operate the internal combustion engine with an air-fuel ratio lying at the lean end of the scale, and ignite the mixture as close to TDC as possi~le. The difficulties associated with these conditions are t~o-fold: firstly, as the mixture is made leaner, it will become increasingly more difficult to ignite with the spark, since the spark constitutes a constant external ~ , '''' ' ::
~77575 .
1 energy source of approximat~ly 0.1 joule/spark energy capacity, and secondly, the resultant drop in flame speed along with spark timing near TDC will result in late combu;tion of the mixture and hence reduced efficiency as well as increased discharge of unburnt hydrocarbons through the exhaust. (On the other hand it is known that in order to increase engine efficiency as well as decrease exhaust emissions it is very desirable to ignite and sustain combustion of a lean mixture in an internal combustion engine).
In view of the foregoing it is a principal object of the present invention to provide a system which increases the efficiency, and a}so reduces the exhaust emissions of an internal combustion engine, which can be installed in existing internal combustion engines, with a minimum of engine modification, and i5 relatively cheap and easy to manufacture and install, and requires relatively low power in operation.
Other objects are to enhance combustion and increase flame speed in the combustion chambers of internal combustion engines and to provide an improved ignition support system fox an internal combustion engine.
Other objects and advantages of the invention will become apparent from the following description of particular preferred embodiments of the invention when read in conjunction with the accompanying drawings.
Briefly, the invention features a system for use with an internal combustion engine having a combustion chamber of predetermined shape, means for producing a combustible mixture therein, and means for igniting the mixture. The system comprises means for generating, and for conducting to the combustion ch~mber, electromagnetic energy at an opera~ing S
~L0775~5 1 frequency, fO, which (a) is of the order of the plasma frequency of a species of charged particles of the mixture, and (b) excites at least one resonant mode of the combustion chamber continuously during the conduction of energy to the combustion chamber. Preferrably, for a combustion chamber that is cylindri-cal in shape, fO is such that a cylindrical resonant cavity mode of the type TM~mo is continuously excited, whereby resonance can be maintained in said combustion chamber independent of its length; the cylindrical resonant cavity mode is the TMolo mode;
and the internal combustion engine is a piston engine having a plurality of combustion chambers with a moveable piston in each and the means for igniting comprise a spark plug for each chamber, each spark plug also connected to deliver the energy at frequency fO to its associated combustion chamber.
Other obiects, ~eatures and advantages o~ the invention will appear from the description below, tc~ken togekher with the accompanying drawing which is a generally schematic illustration of a four cylinder piston engine incorporating the features of the present invention.
The present invention is concerned with coupling microwave energy to igniting and/or combusting air-fuel mixture~
in internal combustion engines so as to enhance the breakdown processes and to increase the speed of combustion reactions.
In oxder to more effectively couple microwave energy to the flame plasma ~and spark plasma where applicable), it is proposed to maintain high electric fields in the vicinity of the flame plasma. It has been realized that this can be accomplished quite easily by operating at electromagnetic wave frequencies with corresponding wavelengths of the orcler of, and less than, the dimensions of the combustion chamber, where ~he 1 chamber is constructed of electrically conductive material.
Typical combustion chamber dimensions lie in the 1 cm to 1 meter range. Frequencies correspondillg to this length range lie in the 3 x 108 Hz to 3 x 101 Hz range. Hence, since wavelengths should be of the order of and less than the 1 cm to 1 meter range, a practical working frequency range for energy supplied to the combustion chamber is 108 ~z to l2 Hz.
Another criterion for effective coupling of microwave energy to flame plasmas is based on the realization that a plasma responds differently at different frequencies. Generally speaking, when the angular electron plasma frequency is of the order of (i.e., withln one order of magnitude) khe electron neutral collision ~requency, one obtains optimum coupling of microwave energy to the plasma by operating at a frequency of the order of the plasma frequency. The angular electron plasma frequency is defined by Wpe = ne me~O
where ne and me are the e}ectron number density and mass, respectively; e is the electronic charge; and ~O is the dielectric constant of free space~
According to the present invention, it has been realised that the electron plasma frequency fp of electrons in hydrocarbon-air flames at atmospheric pressures where fp = Wp/21~ , is of the order of 101 Hz, a number well in the frequency range that was specified above as being ideal for more effective coupling to flames in engines. Hence, a metallic combustion chamber is an ideal environment for coupling of microwaves to hydrocarbon flame plasmas.
. , .
10~7575 1 For combustion chambers of arbitrary shape or changing shape, one can optimize coupling of the microwave energy by operating at frequencies with corresponding wavelengths smaller than the chamber dimensions. In this way microwave energy can be radiated out to the flame, and also one or more standing waves, or cavity modes, can be set up which permits the main-tenance of continuous high electric fields. Generally speaking, the chamber acts as a storage system of electrical field energy, and an equilibrium is maintained between the microwave power that is absorbed by the flame plasma (and walls) and that which is fed to the chamber by the microwave source. In the chamber, the power stored will be many times that dissipated in the flame plasma ~and walls), and i5 directly related to the Quality Factor (Q) o~ the chamber, where Q is:
Q - 2~rf ttime-average energy stored in system) energy loss per second in system For combustion chambers with some degree of symmetry, one can attempt to excite one particular cavity mode. This may be advantageous for at least two reasons:
1. It will allow one to predetermine the electric ~0 field configuration in the cavity and hence pick that particular mode which optimizes coupling of microwave energy to the Elame plasma; and
The concern over air pollution and the dwindling of petroleum resources has resulted in legislation which has caused a shif~ in emphasis from powerful, high compression engines to small, low compression ones. As the degree of pollution which an automobile introduces into the air is measured in parts per mile, a smaller, lower compression engine, burning a leaner mixture (i.e., a higher ratio of air to fuel) can more readily satisfy the pollution requirements.
It is known on the one hand that the level of C0 (carbon monoxide) produced by the internal combustion engina decreases as the air-fuel ratio is increased, and cc)ntinues to decroa~e beyond the "chemlcally ideal" ratlo of 1~.7, and the decrease extends to the "lean limit", i.e., the limit at which flame speed drops to zero and at which the air-fuel mixture does not ordinarily ignite. The production of N0x (oxides of nitrogen), on the other hand, is most sensitive to the time at which the spark is fired ~given in degrees before top dead center, BTDC). The production of N0x in parts per mile, jumps from approximately 1,000 to 3,000 parts when the spark timing is advanced over a 20 range. In order to reduce carbon monoxide, oxides of nitrogen and also other hydrocarbons, therefore, one must operate the internal combustion engine with an air-fuel ratio lying at the lean end of the scale, and ignite the mixture as close to TDC as possi~le. The difficulties associated with these conditions are t~o-fold: firstly, as the mixture is made leaner, it will become increasingly more difficult to ignite with the spark, since the spark constitutes a constant external ~ , '''' ' ::
~77575 .
1 energy source of approximat~ly 0.1 joule/spark energy capacity, and secondly, the resultant drop in flame speed along with spark timing near TDC will result in late combu;tion of the mixture and hence reduced efficiency as well as increased discharge of unburnt hydrocarbons through the exhaust. (On the other hand it is known that in order to increase engine efficiency as well as decrease exhaust emissions it is very desirable to ignite and sustain combustion of a lean mixture in an internal combustion engine).
In view of the foregoing it is a principal object of the present invention to provide a system which increases the efficiency, and a}so reduces the exhaust emissions of an internal combustion engine, which can be installed in existing internal combustion engines, with a minimum of engine modification, and i5 relatively cheap and easy to manufacture and install, and requires relatively low power in operation.
Other objects are to enhance combustion and increase flame speed in the combustion chambers of internal combustion engines and to provide an improved ignition support system fox an internal combustion engine.
Other objects and advantages of the invention will become apparent from the following description of particular preferred embodiments of the invention when read in conjunction with the accompanying drawings.
Briefly, the invention features a system for use with an internal combustion engine having a combustion chamber of predetermined shape, means for producing a combustible mixture therein, and means for igniting the mixture. The system comprises means for generating, and for conducting to the combustion ch~mber, electromagnetic energy at an opera~ing S
~L0775~5 1 frequency, fO, which (a) is of the order of the plasma frequency of a species of charged particles of the mixture, and (b) excites at least one resonant mode of the combustion chamber continuously during the conduction of energy to the combustion chamber. Preferrably, for a combustion chamber that is cylindri-cal in shape, fO is such that a cylindrical resonant cavity mode of the type TM~mo is continuously excited, whereby resonance can be maintained in said combustion chamber independent of its length; the cylindrical resonant cavity mode is the TMolo mode;
and the internal combustion engine is a piston engine having a plurality of combustion chambers with a moveable piston in each and the means for igniting comprise a spark plug for each chamber, each spark plug also connected to deliver the energy at frequency fO to its associated combustion chamber.
Other obiects, ~eatures and advantages o~ the invention will appear from the description below, tc~ken togekher with the accompanying drawing which is a generally schematic illustration of a four cylinder piston engine incorporating the features of the present invention.
The present invention is concerned with coupling microwave energy to igniting and/or combusting air-fuel mixture~
in internal combustion engines so as to enhance the breakdown processes and to increase the speed of combustion reactions.
In oxder to more effectively couple microwave energy to the flame plasma ~and spark plasma where applicable), it is proposed to maintain high electric fields in the vicinity of the flame plasma. It has been realized that this can be accomplished quite easily by operating at electromagnetic wave frequencies with corresponding wavelengths of the orcler of, and less than, the dimensions of the combustion chamber, where ~he 1 chamber is constructed of electrically conductive material.
Typical combustion chamber dimensions lie in the 1 cm to 1 meter range. Frequencies correspondillg to this length range lie in the 3 x 108 Hz to 3 x 101 Hz range. Hence, since wavelengths should be of the order of and less than the 1 cm to 1 meter range, a practical working frequency range for energy supplied to the combustion chamber is 108 ~z to l2 Hz.
Another criterion for effective coupling of microwave energy to flame plasmas is based on the realization that a plasma responds differently at different frequencies. Generally speaking, when the angular electron plasma frequency is of the order of (i.e., withln one order of magnitude) khe electron neutral collision ~requency, one obtains optimum coupling of microwave energy to the plasma by operating at a frequency of the order of the plasma frequency. The angular electron plasma frequency is defined by Wpe = ne me~O
where ne and me are the e}ectron number density and mass, respectively; e is the electronic charge; and ~O is the dielectric constant of free space~
According to the present invention, it has been realised that the electron plasma frequency fp of electrons in hydrocarbon-air flames at atmospheric pressures where fp = Wp/21~ , is of the order of 101 Hz, a number well in the frequency range that was specified above as being ideal for more effective coupling to flames in engines. Hence, a metallic combustion chamber is an ideal environment for coupling of microwaves to hydrocarbon flame plasmas.
. , .
10~7575 1 For combustion chambers of arbitrary shape or changing shape, one can optimize coupling of the microwave energy by operating at frequencies with corresponding wavelengths smaller than the chamber dimensions. In this way microwave energy can be radiated out to the flame, and also one or more standing waves, or cavity modes, can be set up which permits the main-tenance of continuous high electric fields. Generally speaking, the chamber acts as a storage system of electrical field energy, and an equilibrium is maintained between the microwave power that is absorbed by the flame plasma (and walls) and that which is fed to the chamber by the microwave source. In the chamber, the power stored will be many times that dissipated in the flame plasma ~and walls), and i5 directly related to the Quality Factor (Q) o~ the chamber, where Q is:
Q - 2~rf ttime-average energy stored in system) energy loss per second in system For combustion chambers with some degree of symmetry, one can attempt to excite one particular cavity mode. This may be advantageous for at least two reasons:
1. It will allow one to predetermine the electric ~0 field configuration in the cavity and hence pick that particular mode which optimizes coupling of microwave energy to the Elame plasma; and
2. It will allow one to operate at a lower microwave frequency, which may permit using power microwave solid state sources. These are currently more readily available at frequencies below 5 x 109 Hz. Microwave solid state sources are typically powered by low voltage DC, such as 12v DC (the standard automobile voltage).
, 30 .
~7757~
1 For chambers with cylindrical s~mm~try (or even merely circular symmetry, such as combustion charnbers of jet engines, gas turbines, etc), one can excite cylindrical transverse magnetic TMe m n modes or transverse elec~ric TE~ m n modes, where the subscripts ~,m,n denote the numher of standing waves (half wavelengths) in the angular direction, radial direction, and axial direction, respectively. The electromagnetic field components associated with these various modes are known to those skilled in microwave engineering. For example, the transverse magnetic mode TMomo has the following non-zero elec-tromagnetic field components: Ez ~r), He (r), where r, o, z are the radial, angular and axial po~ition variables, Ez is the axial electric ~ield Ho is the angular magnetic field.
~z ~r), El~ ~r) vary as a ~unction o~ radiu~ but are constant in the angular and axial directions. The TMomo mode will have m half wavelength variations in the radial direction.
The T~ mO modes are particularly interesting in that they can be continuously excited and maintained, in a conventional cylindrical piston-type engine with a fixed frequency of elec-tromagnetic energy while the engine i8 running, since khe modedoes not depend upon the axial displacement. Only the Q o the combustion chamber will vary signiicantly with plston position;
the resonant frequency for TM~mo modes, for practical purposes, remains constant.
As is known, there is a spark plasma associated with the high voltage breakdown fields generated by the spark plugs of a conventional piston-type internal combustion engine. In order to optimize coupling of microwave energy to the spark plasma (as well as flame plasma), one can ground the spark to the piston face when firing occurs near ~Itop dead centor"
~ 6 --~775~5 1 in the piston's cycle. In this way, the larger resonant cavity chamber electric fields (the Ez(r) field) are available and can be dumped into the spark plasma (with obvious lowering of cavity Q) to increase both the spark magnitude and duration. ~s the microwave-enhanced DC spark dissipates, t.he resonant field Ez(r) builds up again (cavity Q increases) and microwave energy is transferred to the initial flame plasma to maintain lean mixture flame propagation and increase flame speed.
For illustrative purposes, there is shown in the drawing a schematic illustration of a four cylinder piston-type internal combustion engine incorporating features of the present invention. Referring now to the drawing, there is shown a high frequency power oscillator or source 10, wh:;ch may be one o~ many commercial CW magnetrons. The source 10 ma~ be powered by an alltomotive power system (not shown). ~ remotely actuated coaxial relay switch 12 is coupled to the source 10 via coaxial cable 14. A distributor 16 provides the timing or introducing -the DC electrical energy into each cylinder.
Coaxial cables 18a-d electrically couple the output of switch 12 with spark plugs 20. (To simplify the drawing only a single spark plug 20, cylinder 22, and pist.on 23 are shown).
Suitable spark plug designs for receiving, and for conveying to the combustion chamber 22, high Erequency ene:rgy are described in the applicant's U.S. patent 3,934,566 which issued January 27, 1976. High voltage DC blocks 24a-d are provided in the coaxial . .lines 18a-d between the sources 10 and the spark plugs 20 to insure that high voltage does not reach the microwave sources 10, while allowing the microwave energy to propagate with small reflection. The distributor 16, which distributes the DC high .30 voltage to each cylinder, is coupled via coaxial cables 26a-d to ' .~
/ - 7 _ . ,,~--^, . .
~, :~77~i'75 1 cables 18a-d above the spark plugs. Po~er high frequency filters 28a-d are provided in cables 26a d between distributor 16 and cables 18a-d to insure that high frequency power does not reach the distribu-tor and the environ~ent, but are chosen to carry with-out breakdown the high voltage DC. Lines 30a-d couple the switch 12 to the distributor 16, which provides t:he timing for the operation of switch 12. High voltage breakdown fields are produced between the tip of the central conductor of the spark plug 20 and the surface of the piston 23.
Typically, the cylindrical combustion chamber 22 will have dimensions dictated by conven~ional design criteria for internal combustion engines. For the particular combustion chamber dimensions of any particular engine, the high Ere~uency chosen is one which excites at least one of the r~onant cylindrical cavity mode~, as discussed ~bove. ~s also discussed above, if a TM~mo mode is to be excited, the movement of the piston 23 will not "de-tune" the cylindrical cavity 22 despite its reciprocating motion which continuously changes the length of the cylindrical cavity. Thus, higher levels of electric field can be maintained within the cavity 2~ than would be the case if no resonant mode were being excited. These higher field levels, of course, indicate that more hig}l frequency energy is available in the combustion chamber or coupling to the plasma in the flame front of a combusting : air-fuel mixture.
While particular preferred embodiments of the present invention have been described in detail herein and illustrated in the accompanying drawing, other embodiments are within the scope of the invention and -the following claims.
, 30 .
~7757~
1 For chambers with cylindrical s~mm~try (or even merely circular symmetry, such as combustion charnbers of jet engines, gas turbines, etc), one can excite cylindrical transverse magnetic TMe m n modes or transverse elec~ric TE~ m n modes, where the subscripts ~,m,n denote the numher of standing waves (half wavelengths) in the angular direction, radial direction, and axial direction, respectively. The electromagnetic field components associated with these various modes are known to those skilled in microwave engineering. For example, the transverse magnetic mode TMomo has the following non-zero elec-tromagnetic field components: Ez ~r), He (r), where r, o, z are the radial, angular and axial po~ition variables, Ez is the axial electric ~ield Ho is the angular magnetic field.
~z ~r), El~ ~r) vary as a ~unction o~ radiu~ but are constant in the angular and axial directions. The TMomo mode will have m half wavelength variations in the radial direction.
The T~ mO modes are particularly interesting in that they can be continuously excited and maintained, in a conventional cylindrical piston-type engine with a fixed frequency of elec-tromagnetic energy while the engine i8 running, since khe modedoes not depend upon the axial displacement. Only the Q o the combustion chamber will vary signiicantly with plston position;
the resonant frequency for TM~mo modes, for practical purposes, remains constant.
As is known, there is a spark plasma associated with the high voltage breakdown fields generated by the spark plugs of a conventional piston-type internal combustion engine. In order to optimize coupling of microwave energy to the spark plasma (as well as flame plasma), one can ground the spark to the piston face when firing occurs near ~Itop dead centor"
~ 6 --~775~5 1 in the piston's cycle. In this way, the larger resonant cavity chamber electric fields (the Ez(r) field) are available and can be dumped into the spark plasma (with obvious lowering of cavity Q) to increase both the spark magnitude and duration. ~s the microwave-enhanced DC spark dissipates, t.he resonant field Ez(r) builds up again (cavity Q increases) and microwave energy is transferred to the initial flame plasma to maintain lean mixture flame propagation and increase flame speed.
For illustrative purposes, there is shown in the drawing a schematic illustration of a four cylinder piston-type internal combustion engine incorporating features of the present invention. Referring now to the drawing, there is shown a high frequency power oscillator or source 10, wh:;ch may be one o~ many commercial CW magnetrons. The source 10 ma~ be powered by an alltomotive power system (not shown). ~ remotely actuated coaxial relay switch 12 is coupled to the source 10 via coaxial cable 14. A distributor 16 provides the timing or introducing -the DC electrical energy into each cylinder.
Coaxial cables 18a-d electrically couple the output of switch 12 with spark plugs 20. (To simplify the drawing only a single spark plug 20, cylinder 22, and pist.on 23 are shown).
Suitable spark plug designs for receiving, and for conveying to the combustion chamber 22, high Erequency ene:rgy are described in the applicant's U.S. patent 3,934,566 which issued January 27, 1976. High voltage DC blocks 24a-d are provided in the coaxial . .lines 18a-d between the sources 10 and the spark plugs 20 to insure that high voltage does not reach the microwave sources 10, while allowing the microwave energy to propagate with small reflection. The distributor 16, which distributes the DC high .30 voltage to each cylinder, is coupled via coaxial cables 26a-d to ' .~
/ - 7 _ . ,,~--^, . .
~, :~77~i'75 1 cables 18a-d above the spark plugs. Po~er high frequency filters 28a-d are provided in cables 26a d between distributor 16 and cables 18a-d to insure that high frequency power does not reach the distribu-tor and the environ~ent, but are chosen to carry with-out breakdown the high voltage DC. Lines 30a-d couple the switch 12 to the distributor 16, which provides t:he timing for the operation of switch 12. High voltage breakdown fields are produced between the tip of the central conductor of the spark plug 20 and the surface of the piston 23.
Typically, the cylindrical combustion chamber 22 will have dimensions dictated by conven~ional design criteria for internal combustion engines. For the particular combustion chamber dimensions of any particular engine, the high Ere~uency chosen is one which excites at least one of the r~onant cylindrical cavity mode~, as discussed ~bove. ~s also discussed above, if a TM~mo mode is to be excited, the movement of the piston 23 will not "de-tune" the cylindrical cavity 22 despite its reciprocating motion which continuously changes the length of the cylindrical cavity. Thus, higher levels of electric field can be maintained within the cavity 2~ than would be the case if no resonant mode were being excited. These higher field levels, of course, indicate that more hig}l frequency energy is available in the combustion chamber or coupling to the plasma in the flame front of a combusting : air-fuel mixture.
While particular preferred embodiments of the present invention have been described in detail herein and illustrated in the accompanying drawing, other embodiments are within the scope of the invention and -the following claims.
Claims (22)
1. A system for use with an internal combustion engine having a combustion chamber of predetermined shape, means for producing a combustible mixture therein, and means for igniting said mixture, the system comprising means for generat-ing, and for conducting to said combustion chamber, electro-magnetic energy at an operating frequency, fo, which (a) is of the order of the plasma frequency of a species of charged particles of said mixture, and (b) excites at least one resonant mode of said combustion chamber continuously during the conduction of said energy to said combustion chamber.
2. The system of claim 1 wherein said combustion chamber possesses circular symmetry and said frequency fo is such that at least one waveguide resonant combustion chamber mode is continuously excited during combustion, thereby enabling large electric fields to be maintained in the region of combustion in said combustion chamber.
3. The system of claim 2 wherein said combustion chamber is cylindrical in shape and at least one cylindrical waveguide resonant combustion chamber mode is continuously excited during combustion.
4. The system of claim 3 wherein said combustion chamber is a jet engine combustion chamber.
5. The system of claim 3 wherein said combustion chamber is a gas turbine combustion chamber.
6. The system of claim 1 wherein said combustion chamber is cylindrical in shape and wherein said operating frequency, fo, is such that a cylindrical resonant cavity mode of the
6. The system of claim 1 wherein said combustion chamber is cylindrical in shape and wherein said operating frequency, fo, is such that a cylindrical resonant cavity mode of the
Claim 6 continued:
type TM?mo is continuously excited during said conduction of electromagnetic energy to said combustion chamber, whereby resonance can be maintained in said combustion chamber independent of its length.
type TM?mo is continuously excited during said conduction of electromagnetic energy to said combustion chamber, whereby resonance can be maintained in said combustion chamber independent of its length.
7. The system of claim 6 wherein said internal combustion engine is a piston engine having a plurality of said combustion chambers with a movable piston in each, said electromagnetic energy being conducted to each of said combustion chambers.
8. The system of claim 6 wherein said cylindrical resonant cavity mode is the TM010 mode.
9. The system of claim 8 wherein said internal combustion engine is a piston engine having a plurality of said combustion chambers with a movable piston in each, said electromagnetic energy being conducted to each of said combustion chambers.
10. The system of claim 7 wherein said means for igniting said mixture comprise a spark plug extending into each of said combustion chambers, each of said spark plugs having a control conductor for generating high voltage breakdown fields, said breakdown fields being produced between the tip of said central conductor and the surface of the associated piston facing the spark plug.
11. The system of claim 10 wherein said frequency, fo, is such that the particular TM?mo mode which is excited has its maximum electric field component in the vicinity of the region where said high voltage breakdown fields are produced, so as to enhance the breakdown and combustion processes.
12. The system of claim 11 wherein said means for generating and for conducting to said combustion chamber electro-magnetic energy at an operating frequency, fo, comprise a micro-wave source coupled to said spark plug.
13. In a system for use with an internal combustion engine having a cylindrical combustion chamber and means for producing a combustible mixture therein, the system comprising an energy source means for generating rf electro-magnetic energy, where rf energy is energy having a frequency in the range of about 108 Hz to about 1012 Hz, and for generating high voltage breakdown fields, and means for conducting said rf energy and said high voltage breakdown fields to said chamber to precondition said mixture for combustion, ignite said mixture, and enhance combustion reactions, the improvement wherein energy source generates rf electromagnetic energy at a frequency such that one of the TM?m0 cylindrical resonant cavity modes is continuously excited when said rf electromagnetic energy is conducted to said chamber.
14. The system of claim 13 wherein said cylindrical resonant cavity mode is the TM010 mode.
15. The system of claim 13 wherein said internal combustion engine is a piston engine and said means for generat-ing high voltage breakdown fields comprise the central conductor of a spark plug, said breakdown fields being produced between the tip of said central conductor and the surface of the associated piston facing said spark plug.
16. The system of claim 15 wherein said rf energy is conducted to said chamber through said spark plug.
17. The system of claim 15 wherein said energy source generates electromagnetic energy at a frequency such that the particular TM?m0 mode which is excited has its maximum electric field component in the vicinity of the region where said high voltage breakdown fields are produced, thereby enhancing the breakdown and combustion processes.
18. The system of claim 17 wherein said internal combustion engine has a plurality of said combustion chambers and associated pistons, said electromagnetic energy being conducted to each of said combustion chambers.
19. The system of claim 18 wherein said means for generating high voltage breakdown fields comprise the central conductor of a spark plug, and said rf energy is conducted to said chamber through said spark plug.
20. The method of operating an internal combustion engine comprising at least one generally cylindrical combustion chamber, the method comprising supplying to each said combus-tion chamber continuously during ignition and combustion therein electromagnetic energy at an operating frequency, fo, which (a) is of the order of the plasma frequency of a species of charged particles of the combustion in the combustion chamber, and (b) excites at least one resonant mode of said combustion chamber continuously during the conduction of said electromag-netic energy to said combustion chamber.
21. The method of claim 20 wherein a cylindrical resonant cavity mode of the type TM?m0 is continuously excited during said conduction of electromagnetic energy to said combustion chamber.
22. The method of claim 21 wherein said cylindrical resonant cavity is the TM0m0 mode.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US62216575A | 1975-10-14 | 1975-10-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1077575A true CA1077575A (en) | 1980-05-13 |
Family
ID=24493159
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA263,385A Expired CA1077575A (en) | 1975-10-14 | 1976-10-14 | System for improving combustion in an internal combustion engine |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5274708A (en) |
| CA (1) | CA1077575A (en) |
| DE (1) | DE2646446A1 (en) |
| GB (1) | GB1544461A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017066398A1 (en) * | 2015-10-13 | 2017-04-20 | H Quest Partners, LP | Wave modes for the microwave induced conversion of coal |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2924910A1 (en) * | 1979-06-20 | 1981-01-22 | Selim Dipl Ing Mourad | IC engine spark plug using laser energy - has condenser lens system focussing laser light to point within combustion chamber |
| DE102006005792B4 (en) * | 2006-02-07 | 2018-04-26 | Fachhochschule Aachen | High frequency ignition system for motor vehicles |
| WO2013011967A1 (en) * | 2011-07-16 | 2013-01-24 | イマジニアリング株式会社 | Internal combustion engine |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2617841A (en) * | 1949-01-03 | 1952-11-11 | Rca Corp | Internal-combustion engine ignition |
| US3934566A (en) * | 1974-08-12 | 1976-01-27 | Ward Michael A V | Combustion in an internal combustion engine |
-
1976
- 1976-10-13 GB GB4249076A patent/GB1544461A/en not_active Expired
- 1976-10-14 DE DE19762646446 patent/DE2646446A1/en not_active Ceased
- 1976-10-14 CA CA263,385A patent/CA1077575A/en not_active Expired
- 1976-10-14 JP JP12235476A patent/JPS5274708A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017066398A1 (en) * | 2015-10-13 | 2017-04-20 | H Quest Partners, LP | Wave modes for the microwave induced conversion of coal |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5274708A (en) | 1977-06-23 |
| GB1544461A (en) | 1979-04-19 |
| DE2646446A1 (en) | 1977-04-21 |
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