CA2050357C - Microwave generators and focusing devices for the generators - Google Patents
Microwave generators and focusing devices for the generatorsInfo
- Publication number
- CA2050357C CA2050357C CA 2050357 CA2050357A CA2050357C CA 2050357 C CA2050357 C CA 2050357C CA 2050357 CA2050357 CA 2050357 CA 2050357 A CA2050357 A CA 2050357A CA 2050357 C CA2050357 C CA 2050357C
- Authority
- CA
- Canada
- Prior art keywords
- microwave
- generator
- pattern
- array
- microwave energy
- 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 - Lifetime
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Abstract
There is provided a new and useful apparatus comprising a microwave generator, and a parabolic wave guide associated with the generator for focusing microwave energy over a predetermined area. Multiple such generators are used in an apparatus for treating materials by the application of microwaves.
Description
~ 2050357 FIBLD OF THB INVBNTION
This application relates to microwave generators and focusing devices for the generators; and to apparatus employing focused microwaves.
BACRGROUND OF THB INVBNTION
Microwave generators utilized in industrial processes have generally been very inefficient in that they have utilized in general the technique of simply bombarding a material being treated in a manner which leads to a very non-uniform distribution of microwave energy through the material. The result in such cases is that some parts of the material are undertreated and others overtreated.
In such cases, in order to ensure that all material receives a minimum input of microwave energy, a great deal of lS energy waste occurs.
Furthermore, depending on the material being processed, specific patterns of applied microwaves may be much more efficient than others. With the commonly used general bombarding approach, such varying patterns are not available.
Serious problems of energy loss have also existed in using various wave guide types to distribute generated microwaves.
For example, some wave guides have had elongated and non-linear paths and have resulted in only weak waves reaching the site of a material to be treated.
Further, a view has been firmly held by some manufacturers of microwave units that multiple wave generators are ~ - 2 - 2050~5 7 an impractical solution to the distribution problem because of the problem of interference between waves produced by the various generators.
For these and other reasons there has been an ongoing need for a more efficient manner of applying microwave energy to the material being processed.
It is against this background that a much more efficient apparatus has been developed for generating and delivering microwave energy to a material being processed.
PRIOR ART
The prior art known to the applicant has not provided a means for effectively focusing and distributing microwave energy in an efficient manner.
U.S. Patent 4,123,230, granted October 31, 1978, to Kirkbride, suggests the use of multiple wave sources, but these are used to provide microwaves of different frequencies. There is no suggestion of focusing nor of creating a uniform or preferred distribution pattern.
U.S. Patent 4,184,614, granted April 10, 1979, also to Kirkbride, describes a somewhat different process than that set out in the preceding reference but contains the same material in respect of the microwave energy.
Similarly, a third Kirkbride patent, U.S. Patent 4,234,402, issued November 18, 1980, describes the same microwave generator arrangement.
_ 3 _ 2050357 U.S. Patent 4,376,034, granted March 8, 1983, to Wall, shows use of a pair of microwave generators at opposite ends of a reactor. A very inefficient use of reflected waves is the basis of this microwave application.
The prior art has generally not addressed itself to the more efficient use of microwaves, but has simply incorporated into various processes commercially available microwave generation systems.
It has now been determined that highly efficient microwave application patterns can be developed utilizing a microwave generator in combination with a focusing device.
Multiple such units can be utilized in many instances.
Thus, the invention provides a microwave generating apparatus comprising a microwave generator, and a parabolic wave guide associated with the generator for focusing microwave energy over a predetermined area.
In one preferred embodiment the focus of the microwaves is adjustable.
There is further provided a microwave generating apparatus for applying microwave energy to a material to be treated, the apparatus comprising at least one microwave generator, an antenna connected to each generator for transmitting microwave energy from the generator, and a reflecting surface for reflecting microwave energy from each antenna in a predetermined pattern onto the material to be treated.
There is further provided an apparatus for the controlled reduction of organic materials comprising a microwave tunnel, and an array of microwave generating apparatus for generating focused microwave energy in the tunnel, each apparatus comprising (i) at least one microwave generator, (ii) an antenna connected to each generator for transmitting microwave energy from the generator, and (iii) a reflecting surface for reflecting microwave energy from each antenna in a predetermined pattern onto the material to be treated.
In drawings which illustrate embodiments of the invention, FIGURE 1 is a schematic view of an apparatus according to the invention; and FIGURE 2 is a plan view of a microwave application pattern obtained using the apparatus of the invention.
While the invention will be described in conjunction with illustrated embodiments, it will be understood that it is not intended to limit the invention to such embodiments. On the contrary, it is intended to cover alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
-DBTAILBD DB8CRIPTION OF T~B Yk~nK~v BMBODINENT8 In the following description, similar features in the drawings have been given similar reference numerals.
FIGURE 1 illustrates a microwave generating apparatus 10 according to the invention comprising a magnetron 12, an antenna 14 and a reflecting surface or wave guide 16. The apparatus 10 is illustrated mounted in wall 18 of a microwave chamber 20. The outer extremity 22 of reflecting surface 16 is mounted flush with wall 18. The opening defined by the extremity 22 of reflecting surface 16 is covered by a ceramic plate 24.
The reflecting surface 16 may be designed to achieve a desired pattern of wave application but in the preferred case is substantially parabolic to provide a substantially circular pattern of wave application. The top 17 of the reflecting surface 16 is preferably flattened. This allows for easy mounting of the unit but also allows the antenna 14 to be positioned at or near the focus of the parabola.
The boundaries of the pattern may be adjusted by appropriate design of the wave guide in combination with a particular placement of antenna 14. The focus of the pattern can subsequently preferably be adjusted by adjusting placement of antenna 14. The antenna 14 is preferably adjustable over about one inch of travel axially of the reflector 16.
Thus, for example, in the most preferred configuration the combination of the antenna 14 and reflecting surface 16 is adjusted to provide a slightly off focus application of microwaves _ - 6 -so that the diameter of the area of application of microwaves is greater than the diameter of the extremity 22 of reflecting surface 16.
Application of microwaves is fairly uniform over the circular pattern.
A series of apparatus 10 can then be arranged as illustrated in FIGURE 2 to provide the desired overlapping pattern 26, the area of which is defined by lines 25 through the outer ones 27 of the generators 10 of the array. In this configuration there is produced in effect a microwave cloud which will provide a reasonably uniform distribution of microwave energy to a material 28 in chamber 20.
In a preferred configuration the apparatus 10 is provided with a temperature sensor 30 mountéd in the housing 32 of magnetron 12. Sensor 30 is in turn connected by conductors 31 to a controller 34 which will switch off magnetron 12 via conductors 33 when the sensor 30 registers a limiting temperature and will switch magnetron 12 back on after a preset time period.
Thus, where a non-uniform feed material such as motor vehicle tires is being processed, at times there will be no material beneath an apparatus 10 as, for example, when the open center part of a tire is passing underneath the apparatus. In that case waves reflected from the bottom wall 36 of chamber 20 will cause the apparatus 10 to heat up to the point where the sensor 30 will send a signal to controller 34 causing the magnetron to shut down. After a predetermined period which in the tire case would relate to the time required for the open area of the tire to pass ~050357 _ - 7 -the apparatus 10, magnetron 12 will be switched back on.
This has the combined effect of preventing the apparatus 10 from overheating, and of saving energy.
While the process is widely applicable, and thus highly variable in construction, in a typical case, for example, for reduction of motor vehicle tires, a series of modular tunnels may be used to provide a rectangular tunnel of 40 feet in length and with a cross section of about 14 inches by 36 inches. A series of 12 overlapping magnetrons may be used in each module as shown in FIGURE 2. Each magnetron may have 1.5 kilowatts of power at a wavelength of 2450 MHz.
The typical process will be carried out at a slight positive pressure of about 1/4 to 1/2 inch of water and at maximum temperatures of about 350 C. The sensor 30 will typically switch i5 off the magnetron at a temperature of about 70 C.
Typically the reflectors 16 have a diameter of about 7 1/2 inches to 7 3/4 inches at the extremity of the parabola. The top section 17 is typically about 3 1/8 inches wide and the reflector about 2 1/2 inches deep.
Thus it is apparent that there has been provided in accordance with the invention a microwave generating apparatus that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the invention.
This application relates to microwave generators and focusing devices for the generators; and to apparatus employing focused microwaves.
BACRGROUND OF THB INVBNTION
Microwave generators utilized in industrial processes have generally been very inefficient in that they have utilized in general the technique of simply bombarding a material being treated in a manner which leads to a very non-uniform distribution of microwave energy through the material. The result in such cases is that some parts of the material are undertreated and others overtreated.
In such cases, in order to ensure that all material receives a minimum input of microwave energy, a great deal of lS energy waste occurs.
Furthermore, depending on the material being processed, specific patterns of applied microwaves may be much more efficient than others. With the commonly used general bombarding approach, such varying patterns are not available.
Serious problems of energy loss have also existed in using various wave guide types to distribute generated microwaves.
For example, some wave guides have had elongated and non-linear paths and have resulted in only weak waves reaching the site of a material to be treated.
Further, a view has been firmly held by some manufacturers of microwave units that multiple wave generators are ~ - 2 - 2050~5 7 an impractical solution to the distribution problem because of the problem of interference between waves produced by the various generators.
For these and other reasons there has been an ongoing need for a more efficient manner of applying microwave energy to the material being processed.
It is against this background that a much more efficient apparatus has been developed for generating and delivering microwave energy to a material being processed.
PRIOR ART
The prior art known to the applicant has not provided a means for effectively focusing and distributing microwave energy in an efficient manner.
U.S. Patent 4,123,230, granted October 31, 1978, to Kirkbride, suggests the use of multiple wave sources, but these are used to provide microwaves of different frequencies. There is no suggestion of focusing nor of creating a uniform or preferred distribution pattern.
U.S. Patent 4,184,614, granted April 10, 1979, also to Kirkbride, describes a somewhat different process than that set out in the preceding reference but contains the same material in respect of the microwave energy.
Similarly, a third Kirkbride patent, U.S. Patent 4,234,402, issued November 18, 1980, describes the same microwave generator arrangement.
_ 3 _ 2050357 U.S. Patent 4,376,034, granted March 8, 1983, to Wall, shows use of a pair of microwave generators at opposite ends of a reactor. A very inefficient use of reflected waves is the basis of this microwave application.
The prior art has generally not addressed itself to the more efficient use of microwaves, but has simply incorporated into various processes commercially available microwave generation systems.
It has now been determined that highly efficient microwave application patterns can be developed utilizing a microwave generator in combination with a focusing device.
Multiple such units can be utilized in many instances.
Thus, the invention provides a microwave generating apparatus comprising a microwave generator, and a parabolic wave guide associated with the generator for focusing microwave energy over a predetermined area.
In one preferred embodiment the focus of the microwaves is adjustable.
There is further provided a microwave generating apparatus for applying microwave energy to a material to be treated, the apparatus comprising at least one microwave generator, an antenna connected to each generator for transmitting microwave energy from the generator, and a reflecting surface for reflecting microwave energy from each antenna in a predetermined pattern onto the material to be treated.
There is further provided an apparatus for the controlled reduction of organic materials comprising a microwave tunnel, and an array of microwave generating apparatus for generating focused microwave energy in the tunnel, each apparatus comprising (i) at least one microwave generator, (ii) an antenna connected to each generator for transmitting microwave energy from the generator, and (iii) a reflecting surface for reflecting microwave energy from each antenna in a predetermined pattern onto the material to be treated.
In drawings which illustrate embodiments of the invention, FIGURE 1 is a schematic view of an apparatus according to the invention; and FIGURE 2 is a plan view of a microwave application pattern obtained using the apparatus of the invention.
While the invention will be described in conjunction with illustrated embodiments, it will be understood that it is not intended to limit the invention to such embodiments. On the contrary, it is intended to cover alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
-DBTAILBD DB8CRIPTION OF T~B Yk~nK~v BMBODINENT8 In the following description, similar features in the drawings have been given similar reference numerals.
FIGURE 1 illustrates a microwave generating apparatus 10 according to the invention comprising a magnetron 12, an antenna 14 and a reflecting surface or wave guide 16. The apparatus 10 is illustrated mounted in wall 18 of a microwave chamber 20. The outer extremity 22 of reflecting surface 16 is mounted flush with wall 18. The opening defined by the extremity 22 of reflecting surface 16 is covered by a ceramic plate 24.
The reflecting surface 16 may be designed to achieve a desired pattern of wave application but in the preferred case is substantially parabolic to provide a substantially circular pattern of wave application. The top 17 of the reflecting surface 16 is preferably flattened. This allows for easy mounting of the unit but also allows the antenna 14 to be positioned at or near the focus of the parabola.
The boundaries of the pattern may be adjusted by appropriate design of the wave guide in combination with a particular placement of antenna 14. The focus of the pattern can subsequently preferably be adjusted by adjusting placement of antenna 14. The antenna 14 is preferably adjustable over about one inch of travel axially of the reflector 16.
Thus, for example, in the most preferred configuration the combination of the antenna 14 and reflecting surface 16 is adjusted to provide a slightly off focus application of microwaves _ - 6 -so that the diameter of the area of application of microwaves is greater than the diameter of the extremity 22 of reflecting surface 16.
Application of microwaves is fairly uniform over the circular pattern.
A series of apparatus 10 can then be arranged as illustrated in FIGURE 2 to provide the desired overlapping pattern 26, the area of which is defined by lines 25 through the outer ones 27 of the generators 10 of the array. In this configuration there is produced in effect a microwave cloud which will provide a reasonably uniform distribution of microwave energy to a material 28 in chamber 20.
In a preferred configuration the apparatus 10 is provided with a temperature sensor 30 mountéd in the housing 32 of magnetron 12. Sensor 30 is in turn connected by conductors 31 to a controller 34 which will switch off magnetron 12 via conductors 33 when the sensor 30 registers a limiting temperature and will switch magnetron 12 back on after a preset time period.
Thus, where a non-uniform feed material such as motor vehicle tires is being processed, at times there will be no material beneath an apparatus 10 as, for example, when the open center part of a tire is passing underneath the apparatus. In that case waves reflected from the bottom wall 36 of chamber 20 will cause the apparatus 10 to heat up to the point where the sensor 30 will send a signal to controller 34 causing the magnetron to shut down. After a predetermined period which in the tire case would relate to the time required for the open area of the tire to pass ~050357 _ - 7 -the apparatus 10, magnetron 12 will be switched back on.
This has the combined effect of preventing the apparatus 10 from overheating, and of saving energy.
While the process is widely applicable, and thus highly variable in construction, in a typical case, for example, for reduction of motor vehicle tires, a series of modular tunnels may be used to provide a rectangular tunnel of 40 feet in length and with a cross section of about 14 inches by 36 inches. A series of 12 overlapping magnetrons may be used in each module as shown in FIGURE 2. Each magnetron may have 1.5 kilowatts of power at a wavelength of 2450 MHz.
The typical process will be carried out at a slight positive pressure of about 1/4 to 1/2 inch of water and at maximum temperatures of about 350 C. The sensor 30 will typically switch i5 off the magnetron at a temperature of about 70 C.
Typically the reflectors 16 have a diameter of about 7 1/2 inches to 7 3/4 inches at the extremity of the parabola. The top section 17 is typically about 3 1/8 inches wide and the reflector about 2 1/2 inches deep.
Thus it is apparent that there has been provided in accordance with the invention a microwave generating apparatus that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the invention.
Claims (18)
1. A microwave generating apparatus for the controlled reduction of organic materials in a microwave chamber, said apparatus comprising:
at least one microwave generator;
an antenna connected to each said generator for transmitting microwave energy from said generator; and a reflecting surface for reflecting microwave energy from each said antenna in a specific predetermined pattern onto said material to be reduced.
at least one microwave generator;
an antenna connected to each said generator for transmitting microwave energy from said generator; and a reflecting surface for reflecting microwave energy from each said antenna in a specific predetermined pattern onto said material to be reduced.
2. The apparatus of claim 1 wherein the position of said antenna relative to said reflector is adjustable.
3. The apparatus of claim 1 wherein said reflecting surface is parabolic, having an open face.
4. The apparatus of claim 3 having a ceramic plate across said open face.
5. The apparatus of claim 1 including an array of said generators.
6. The apparatus of claim 5 wherein each said pattern is circular.
7. The apparatus of claim 6 wherein an outer edge of each said pattern overlaps with an outer edge of at least one adjacent pattern.
8. The apparatus of claim 6 wherein each said circular pattern is of slightly greater diameter than the diameter across said face of said reflecting surface.
9. The apparatus of claim 5 wherein said array is a 3 by 4 array.
10. The apparatus of claim 6 wherein said patterns overlap to cover the entire area encompassed within lines through the outer ones of said generators in the array.
11. An apparatus for the controlled reduction of organic materials comprising:
a microwave tunnel; and an array of microwave generating apparatus for generating focused microwave energy in said tunnel;
each said apparatus comprising (i) at least one microwave generator; (ii) an antenna connected to each generator for transmitting microwave energy from said generator; and (iii) a reflecting surface for reflecting microwave energy from each said antenna in a predetermined pattern onto said material to be treated.
a microwave tunnel; and an array of microwave generating apparatus for generating focused microwave energy in said tunnel;
each said apparatus comprising (i) at least one microwave generator; (ii) an antenna connected to each generator for transmitting microwave energy from said generator; and (iii) a reflecting surface for reflecting microwave energy from each said antenna in a predetermined pattern onto said material to be treated.
12. The apparatus of claim 11 wherein each said reflecting surface is parabolic and is mounted with an open face of the parabola substantially flush with a wall of said tunnel.
13. The apparatus of claim 12 having a ceramic plate across said open face.
14. The apparatus of claim 13 wherein said tunnel is of rectangular cross-section having a top wall.
15. The apparatus of claim 14 wherein said array is mounted in said top wall.
16. The apparatus of claim 15 wherein each said predetermined pattern is circular.
17. The apparatus of claim 16 wherein an outer edge of each said pattern overlaps with an outer edge of at least one adjacent pattern.
18. The apparatus of claim 17 wherein said tunnel has a bottom surface and wherein said patterns together cover substantially all of said surface with a substantially uniform amount of microwave energy.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2050357 CA2050357C (en) | 1991-08-30 | 1991-08-30 | Microwave generators and focusing devices for the generators |
| US08/188,350 US5507927A (en) | 1989-09-07 | 1993-09-01 | Method and apparatus for the controlled reduction of organic material |
| US08/539,721 US5877395A (en) | 1989-09-07 | 1995-10-05 | Method and apparatus for the controlled reduction of organic material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2050357 CA2050357C (en) | 1991-08-30 | 1991-08-30 | Microwave generators and focusing devices for the generators |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2050357A1 CA2050357A1 (en) | 1993-03-01 |
| CA2050357C true CA2050357C (en) | 1997-08-19 |
Family
ID=4148278
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2050357 Expired - Lifetime CA2050357C (en) | 1989-09-07 | 1991-08-30 | Microwave generators and focusing devices for the generators |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2050357C (en) |
-
1991
- 1991-08-30 CA CA 2050357 patent/CA2050357C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2050357A1 (en) | 1993-03-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |