CA1038936A - Protective transporter for transporting materials to and from a microwave unit - Google Patents
Protective transporter for transporting materials to and from a microwave unitInfo
- Publication number
- CA1038936A CA1038936A CA233,304A CA233304A CA1038936A CA 1038936 A CA1038936 A CA 1038936A CA 233304 A CA233304 A CA 233304A CA 1038936 A CA1038936 A CA 1038936A
- Authority
- CA
- Canada
- Prior art keywords
- housing
- belts
- microwave
- transporter
- casing
- 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
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/78—Arrangements for continuous movement of material
-
- A—HUMAN NECESSITIES
- A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
- A24B—MANUFACTURE OR PREPARATION OF TOBACCO FOR SMOKING OR CHEWING; TOBACCO; SNUFF
- A24B3/00—Preparing tobacco in the factory
- A24B3/12—Steaming, curing, or flavouring tobacco
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/76—Prevention of microwave leakage, e.g. door sealings
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Constitution Of High-Frequency Heating (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
- Treatment Of Fiber Materials (AREA)
- Structure Of Belt Conveyors (AREA)
- Belt Conveyors (AREA)
Abstract
PROTECTIVE TRANSPORTER FOR TRANSPORTING MATERIALS
TO AND FROM A MICROWAVE UNIT
ABSTRACT OF THE DISCLOSURE
A transporter for transporting materials to and from the cavity of a microwave unit is disclosed, said transporter being effective to prevent any undue microwave leakage from escaping therethrough. The transporter includes an endless transporter belt means disposed in a housing connected to the microwave unit, the belt means traversing tunnels in the housing which function as cut-off tubes to prevent escape of microwave leakage from the cavity of the microwave unit, the tunnels having a rectangular cross-section, the longest side-dimension of which is not greater than 2 inches, the length of the tunnels being at least about 10 inches.
TO AND FROM A MICROWAVE UNIT
ABSTRACT OF THE DISCLOSURE
A transporter for transporting materials to and from the cavity of a microwave unit is disclosed, said transporter being effective to prevent any undue microwave leakage from escaping therethrough. The transporter includes an endless transporter belt means disposed in a housing connected to the microwave unit, the belt means traversing tunnels in the housing which function as cut-off tubes to prevent escape of microwave leakage from the cavity of the microwave unit, the tunnels having a rectangular cross-section, the longest side-dimension of which is not greater than 2 inches, the length of the tunnels being at least about 10 inches.
Description
10~8936 It is known to subject various materials to microwave energy in the cavity of a microwave unit for various purposes, e.g., it being known to employ such technique in connection with the treat-ment of tobacco in cut fiber or shred form for expanding the same.
Presently employed apparatus for this purpose usually includes a conveyor belt to transport the material to and from the cavity, together with a choke at inlet and outlet to absorb any microwave leaking from these openings, which energy if the openings are large enough for practical operating volumes, will otherwise usual-ly far exceed the safe value of 10 mM/cm at a distance of 2inches set by government regulations. The choke is made up of energy-absorbing materials that are cooled by flowing water there--to to carry away the heat. Such an arrangement is expensive to install and to operate. Further, it does not always give the re-quired protection as sh~wn in Table 1, from Eure, John A., James - W. Nocolls, and Robert L. Elder, Am. J. Public Health, 62, 1573-77, Dec., 1972.
A second disadvantage of such known system is that the microwave energy that passes through the cavity opening and is ab-sorbed in the choke represents an energy loss or deviation from theintended purpose of the microwave cavity operation. This loss can be a significant fraction of the total energy supplied to the cavity.
For a small opening in a microwave cavity, an effective leak-age seal that prevents the passage of microwave energy consists of a tube filled with a dielectric such as air and having a length/
diameter ratio of approximately six, with a maximum diamete~ of , --1--,: :. - . :
approximately 2.8 inches. This type of seal or cut-off tube does not require water cooling because it does not absorb any microwave energy. Because of its small diameter, however, such a cut-off tube will not allow passage of most shredded or fibrous particulate matter, even in a vertical position unless some form of material conveying assistance is provided. -~
The present invention relates to a protective transporter apparatus for feeding the material to and from the cavity of a -microwave unit. It is particularly intended for use in a continu-10 ous operation of the microwave unit involving continuous transport ~ -of material to and from the said cavity. While the invention is described in terms particular to the treatment of cut or shredded tobacco filler material, it will be apparent that it can be used for transporting any type of particulate material which is to be treated in a microwave unit.
In accordance with the present invention, the protective transporter is adapted to be mounted on the casing of a microwave -unit over an opening in the casing through which the material is intendet to enter or leave the microwave cavity, the apparatus in-cluding a housing which extends outwardly a distance from thecasing opening. Located within the housing are a pair of drums, one an idler drum located at the end of the housing connected to the casing and adjacent the cavity opening, with the other or power driven drum being located adjacent the other end of the housing. --A plurality of transporter belts are mounted on the two drums and traverse endless travel courses within the housing, with the housing having two pairs of opposed side walls, the belts being disposed such that their endless travel course includes straight -~ , , , ,,, , -. ~ ' '' ' ' :' ' ' ' ':
course runs adjacent to and spaced from the inner surface of one of said pairs of housing side walls. In traversing their endless travel courses, the belts generally are disposed substantially parallel one with the others and to maintain such parallel re-lation between the respective belts, one of the drums, the driven drum, is provided with radial flanges which are disposed between adjacent ones of the belts. Further to facilitate the transport of the material on the belts, the belts may be provided with up-standing lugs spaced along the lengths of the belts.
10Means are provided within the housing to define with the inner surfaces of the said pair of opposed housing side walls a corresponding plurality of pairs of tunnels of rectangular cross section associated one pair of tunnels with each belt and which each said belt traverses during the respective straight course runs thereof, with the longest side dimension of each tunnel cross section being not greater than two inches in length and the length of the tunnels being at least about 10 inches. The tunnels which ~- extend between the two drums conveniently can be provided from partitions which extend inwardly from the inner surfaces of said housing ~ide walls alongside the straight run courses of the belts and panels which extend between the said partitions and which are disposed substantially parallel to the said inner wall surfaces with the belt straight run courses being disposed intermediate the said panels and the said opposed wall inner surfaces. Inasmuch as the tunnel cross section is limited to having a longest side dimen-sion of not more than 2 inches, the tunnel functions as a choke or cut-off tube to restrict or prevent microwave leakage outwardly of the housing.
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In accordance with the invention, the tunnel cross sectional configuration is rectangular and can be square rectangular pro- -vided the longest side of the cross section is not greater than
Presently employed apparatus for this purpose usually includes a conveyor belt to transport the material to and from the cavity, together with a choke at inlet and outlet to absorb any microwave leaking from these openings, which energy if the openings are large enough for practical operating volumes, will otherwise usual-ly far exceed the safe value of 10 mM/cm at a distance of 2inches set by government regulations. The choke is made up of energy-absorbing materials that are cooled by flowing water there--to to carry away the heat. Such an arrangement is expensive to install and to operate. Further, it does not always give the re-quired protection as sh~wn in Table 1, from Eure, John A., James - W. Nocolls, and Robert L. Elder, Am. J. Public Health, 62, 1573-77, Dec., 1972.
A second disadvantage of such known system is that the microwave energy that passes through the cavity opening and is ab-sorbed in the choke represents an energy loss or deviation from theintended purpose of the microwave cavity operation. This loss can be a significant fraction of the total energy supplied to the cavity.
For a small opening in a microwave cavity, an effective leak-age seal that prevents the passage of microwave energy consists of a tube filled with a dielectric such as air and having a length/
diameter ratio of approximately six, with a maximum diamete~ of , --1--,: :. - . :
approximately 2.8 inches. This type of seal or cut-off tube does not require water cooling because it does not absorb any microwave energy. Because of its small diameter, however, such a cut-off tube will not allow passage of most shredded or fibrous particulate matter, even in a vertical position unless some form of material conveying assistance is provided. -~
The present invention relates to a protective transporter apparatus for feeding the material to and from the cavity of a -microwave unit. It is particularly intended for use in a continu-10 ous operation of the microwave unit involving continuous transport ~ -of material to and from the said cavity. While the invention is described in terms particular to the treatment of cut or shredded tobacco filler material, it will be apparent that it can be used for transporting any type of particulate material which is to be treated in a microwave unit.
In accordance with the present invention, the protective transporter is adapted to be mounted on the casing of a microwave -unit over an opening in the casing through which the material is intendet to enter or leave the microwave cavity, the apparatus in-cluding a housing which extends outwardly a distance from thecasing opening. Located within the housing are a pair of drums, one an idler drum located at the end of the housing connected to the casing and adjacent the cavity opening, with the other or power driven drum being located adjacent the other end of the housing. --A plurality of transporter belts are mounted on the two drums and traverse endless travel courses within the housing, with the housing having two pairs of opposed side walls, the belts being disposed such that their endless travel course includes straight -~ , , , ,,, , -. ~ ' '' ' ' :' ' ' ' ':
course runs adjacent to and spaced from the inner surface of one of said pairs of housing side walls. In traversing their endless travel courses, the belts generally are disposed substantially parallel one with the others and to maintain such parallel re-lation between the respective belts, one of the drums, the driven drum, is provided with radial flanges which are disposed between adjacent ones of the belts. Further to facilitate the transport of the material on the belts, the belts may be provided with up-standing lugs spaced along the lengths of the belts.
10Means are provided within the housing to define with the inner surfaces of the said pair of opposed housing side walls a corresponding plurality of pairs of tunnels of rectangular cross section associated one pair of tunnels with each belt and which each said belt traverses during the respective straight course runs thereof, with the longest side dimension of each tunnel cross section being not greater than two inches in length and the length of the tunnels being at least about 10 inches. The tunnels which ~- extend between the two drums conveniently can be provided from partitions which extend inwardly from the inner surfaces of said housing ~ide walls alongside the straight run courses of the belts and panels which extend between the said partitions and which are disposed substantially parallel to the said inner wall surfaces with the belt straight run courses being disposed intermediate the said panels and the said opposed wall inner surfaces. Inasmuch as the tunnel cross section is limited to having a longest side dimen-sion of not more than 2 inches, the tunnel functions as a choke or cut-off tube to restrict or prevent microwave leakage outwardly of the housing.
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.
In accordance with the invention, the tunnel cross sectional configuration is rectangular and can be square rectangular pro- -vided the longest side of the cross section is not greater than
2 inches. The belts which are employed within the housing pre-ferably are provided from a material which has high microwave energy transmission characteristics, such materials including polytetrafluoroethylene, glass fiber-silicone rubber, or any other low-loss material. Further, the invention provides means for adjusting tension in said belts while retaining the feature that the belts travel in tunnels functioning as cut-off tubes.
The invention also provides that the apparatus include a microwave reflector which is supported within the housing adjacent the idler drum and following the contour of said drum in spaced relation therewith, the deflector being located at the side of - -the drum remote from the adjacent end of the housing.
The invention also provides apparatus for subjecting material to microwave treatment which includes a microwave unit having an endless conveyor within the cavity thereof, means for generating microwave energy, an entry opening adjacent one end of the casing and an exit opening for removal of material from the casing. Pro-tective transporter units are provided at both the entry and re-moval openings, such units being of the construction described above.
The invention accordingly comprises the features of construc-tion, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set forth and the scope of the invention will be indicated in the claims.
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According to a broad aspect, the invention relates to a microwave treatment apparatus for treating particulate material by subjecting it to microwave energy, the apparatus comprising a casing enclosing a space defining a microwave cavity, a microwave power source for exciting microwave energy within the casing, and transporters for conveying material to and from said cavity through openings in the casing, each transporter comprising an enclosure comprising a housing having two opposed inner wàll surfaces and means defining with the inner wall surfaces a plurality of pairs of straight tunnels of rectangular cross-section within the housing, the tunnels having wave guide characteristics and predetermined cross-sectional dimensions and length such as to effect attenuation of microwave energy therein resulting from operation of the microwave power source to a level below 10 mw/cm at the tunnel ends remote from the casing opening associated with the transporter, a plurality of separate endless belts, and means for supporting the belts for travel with each belt having two straight runs extending through an associated pair of saia tunnel~
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~038936 A fuller understanding of the nature and objects of the invention will be had from the following detailed description taken in conjunction with the accompanying drawings in which FIGURE 1 is a longitudinal vertical sectional view of improved microwave unit apparatus for subjecting material to microwave energy, the unit also including protective transporter apparatus provided in accordance with the present invention.
FIGURE 2 is a perspective view of the protective transporter apparatus shown at the inlet and outlet openings of the micro-wave apparatus depicted in Figure 1.
FIGURE 3 is a top plan view with portions broken away of the protective transporter apparatus depicted in Figure 2.
FIGURE 4 is a vertical sectional view as taken along the line IV-IV in Figure 3.
FIGURE 5, which is located on the same sheet as Figure 1, is a schematic depiction of a modified form of apparatus which includes means for adjusting tension in the transporter belts.
Throughout the following description like reference numerals are used to denote like parts in the drawings.
Referring to Figure 1, there is depicted apparatus 10 for microwave treatment of material, for example, shredded or cut tobacco filler which is to be subjected to microwaves as an in-cident of expanding the same. Such apparatus 10 includes a casing or microwave unit 12, which is an elongated structure enclosing a cavity 14 into which the material is introduced to subject it to microwave energy. A suitable microwave energy source shown generally at 16 is mounted at the upper part of the casing 12.
The casing 12 is provided with an entry opening 18 and an exit .
.~ . .
opening 20 through which the material can be delivered to and withdrawn from the microwave cavity 14. Entrance opening 1~ con-veniently is located adjacent one end of the casing so that the tobacco material 22 can be deposited therethrough onto a moving endless conveyor belt 24 traversing an endless travel course be-tween roller drums 26 and 28, with the material being transported through the cavity and ultimately being discharged from the belt at the right end of the casing from whence it is delivered through opening 20 for removal from the casing. The apparatus also in-cludes at the entry and discharge openings protective transporterunits 30 which will be described in greater detail below, the transporter units 30 being employed to effectively eliminate any microwave energy leakage through the openings 18 and 20. An in-put hopper 33 can be connected with the protective transporter unit 30 at the entry to the cavity for supplying the material in known manner to the transporter and ultimately delivery into the microwave unit.
Turning now to Figures 2-4, the protective transporter unit 30 comprises an elongated housing which is connected at one of its ends to the microwave unit over the associated cavity with the housing including four side walls 32, 34, 36 and 38, the side walls being arranged in opposed pairs of such walls with the inner surfaces of the walls being of relatively smooth configura-tion and such ~hat each wall inner surface is in parallel spaced disposition with an opposite side wall inner surface, the con-figuration of housing desirably being generally rectangular. At one end of the housing 30 there is provided a flange 40 with which the housing can be connected to the microwave unit. The ' ~ '. .
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~ 038936 opposite end also includes a flange 42 which can be used for a like purpose, for example, in connecting an input hopper unit 33 at the entrance to the transporter unit.
Disposed within the transporter unit housing are a pair of drums 44 and 46 which provide means for supporting a plurality of endless belts 50 for travel through an endless travel course within the housing, the belts in the depicted embodiment tra-versing straight course runs adjacent to and spaced from opposed side walls, 32 and 34. The belts also may be provided with a series of upstanding lugs 52 at spaced locations along the length of each belt, the plurality of belts further being arranged to travel in generally parallel travel courses within the housing and drum 44 being provided with radial flanges 56 disposed be-tween adjacent ones of the belts to maintain them in such parallel disposition. The drum 44 which is remote from the end of the housing that is connected to the microwave cavity, is a driven unit and for such purpose suitable driving mechanism as at 60 can be provided, the shaft 62 associated with drum 44 being rotatably mounted in the other pair of opposed side walls 36, 38.
Idler drum 46 which also is rotatably supported in the housing desirably is electrically insulated from the structure of the walls 36 and 38 and to that end drum 46 is at the opposite ends provided with bushings 68 of electrically insulative material, as for example, polytetrafluoroethylene or other suitable polymer material which are rotatably received on fixed pins 67 carried on the housing walls, the fixed pins being part of the fixed struc- ~ :
ture generally depicted at 69.
In accordance with the present invention and to reduce a microwave leakage to any but inconsequential values, the housing is provided with pairs of tunnels 70 associated one pair each with one of the belts so that during the straight course run of the belt it will travel through the pair of tunnels, with the tunnels having a rectangular cross section the longest side di-mension of which is not greater than 2 inches. Further the tunnels 70 desirably have a length at least about 10 inches. As can be best seen in Figure 4, the tunnels 70 extend between the -two drums 44, 46 and are comprised of partitions 72 extending ~:
inwardly from the opposed side walls 32, 34 at substantially a right angle therewith with the partitions extending alongside the ~ ~
8traight run courses of the belts. Further panels 74 extend ~ -between the partitions and are disposed substantially parallel to and spaced from the inner surfaces of the walls 32, 34. The . :
belts 50 as can be seen in Figure 4 travel in their straight run courses intermediate the inner surfaces of the side walls 32, 34 :
and the panels 74. As indicated above, the cross sectional con- ` :
figuration and dimension of the tunnel is selected such as to produce a cut-off effect without the use of any special dielectric in order to reduce microwave leakage to levels which are below The transporter unit 30 also is provided with a reflector 80 for reflecting microwaves which said reflector is supported in the housing adjacent drum 46 and adjacent to the side of said drum remote from the end of the housing which is connected to the ~ . .
microwave cavity, with the reflector following closely the contour of the drum 46 and being disposed further in spaced relation there-: -8-with. The reflector extends substantlally the full width of the , housing between the side walls 36, 28.
In order to avoid heating the belts, it is desirable that the belts 50 be provided with a material which has low-loss characteristics and for this purpose material such as polytetra-fluoroethylene, glass fiber and silicone rubber can be used for the belts. The structure of the housing desirably is made from any suitable metal as for example stainless steel or aluminum.
The cross section of the tunnels 70 is as mentioned rectan-gular and can be square rectangular so long as the longest sideof said rectangle is not more than two inches in length.
The protective transporter 30 was employed to feed cut tobacco filler into a microwave cavity charged with 30 Kw at a frequency of 2450 MHz. The feeding went smoothly and leakage ;
from the top opening of the feeder was less than 5 mw/cm , measured at the top of tunnels 70.
Figure 5 depicts a modified form of protective transporter unit 130 in which means are provided for adjusting the tension in each of the respective transporter belts.150. Thus the unit 130 includes tunnels 170a associated with the entry travel course run of the belt to the microwave cavity and tunnels 170b, 170c associated with the return travel course run of the belts, the return travel associated tunnels being disposed at angles as shown relative to the entry travel course run tunnels to permit the belts to traverse a course around the pulleys 179 of tensioning units 180, the tunnels 170b, 170c otherwise being in all respects as to dimension and function, the same as earlier described. The side wall structure 181 of the housing is also disposed at an ~0389;~6 angle to the opposite wall structure 183, the structure 181 being for example provided in sections associated with each tunnel 170b, 170c. Thus each belt can be provided with its own tensioning control device without interferring with the purpose of providing effective cut-off tube means at the microwave cavity end of the unit. .
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The invention also provides that the apparatus include a microwave reflector which is supported within the housing adjacent the idler drum and following the contour of said drum in spaced relation therewith, the deflector being located at the side of - -the drum remote from the adjacent end of the housing.
The invention also provides apparatus for subjecting material to microwave treatment which includes a microwave unit having an endless conveyor within the cavity thereof, means for generating microwave energy, an entry opening adjacent one end of the casing and an exit opening for removal of material from the casing. Pro-tective transporter units are provided at both the entry and re-moval openings, such units being of the construction described above.
The invention accordingly comprises the features of construc-tion, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set forth and the scope of the invention will be indicated in the claims.
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According to a broad aspect, the invention relates to a microwave treatment apparatus for treating particulate material by subjecting it to microwave energy, the apparatus comprising a casing enclosing a space defining a microwave cavity, a microwave power source for exciting microwave energy within the casing, and transporters for conveying material to and from said cavity through openings in the casing, each transporter comprising an enclosure comprising a housing having two opposed inner wàll surfaces and means defining with the inner wall surfaces a plurality of pairs of straight tunnels of rectangular cross-section within the housing, the tunnels having wave guide characteristics and predetermined cross-sectional dimensions and length such as to effect attenuation of microwave energy therein resulting from operation of the microwave power source to a level below 10 mw/cm at the tunnel ends remote from the casing opening associated with the transporter, a plurality of separate endless belts, and means for supporting the belts for travel with each belt having two straight runs extending through an associated pair of saia tunnel~
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~038936 A fuller understanding of the nature and objects of the invention will be had from the following detailed description taken in conjunction with the accompanying drawings in which FIGURE 1 is a longitudinal vertical sectional view of improved microwave unit apparatus for subjecting material to microwave energy, the unit also including protective transporter apparatus provided in accordance with the present invention.
FIGURE 2 is a perspective view of the protective transporter apparatus shown at the inlet and outlet openings of the micro-wave apparatus depicted in Figure 1.
FIGURE 3 is a top plan view with portions broken away of the protective transporter apparatus depicted in Figure 2.
FIGURE 4 is a vertical sectional view as taken along the line IV-IV in Figure 3.
FIGURE 5, which is located on the same sheet as Figure 1, is a schematic depiction of a modified form of apparatus which includes means for adjusting tension in the transporter belts.
Throughout the following description like reference numerals are used to denote like parts in the drawings.
Referring to Figure 1, there is depicted apparatus 10 for microwave treatment of material, for example, shredded or cut tobacco filler which is to be subjected to microwaves as an in-cident of expanding the same. Such apparatus 10 includes a casing or microwave unit 12, which is an elongated structure enclosing a cavity 14 into which the material is introduced to subject it to microwave energy. A suitable microwave energy source shown generally at 16 is mounted at the upper part of the casing 12.
The casing 12 is provided with an entry opening 18 and an exit .
.~ . .
opening 20 through which the material can be delivered to and withdrawn from the microwave cavity 14. Entrance opening 1~ con-veniently is located adjacent one end of the casing so that the tobacco material 22 can be deposited therethrough onto a moving endless conveyor belt 24 traversing an endless travel course be-tween roller drums 26 and 28, with the material being transported through the cavity and ultimately being discharged from the belt at the right end of the casing from whence it is delivered through opening 20 for removal from the casing. The apparatus also in-cludes at the entry and discharge openings protective transporterunits 30 which will be described in greater detail below, the transporter units 30 being employed to effectively eliminate any microwave energy leakage through the openings 18 and 20. An in-put hopper 33 can be connected with the protective transporter unit 30 at the entry to the cavity for supplying the material in known manner to the transporter and ultimately delivery into the microwave unit.
Turning now to Figures 2-4, the protective transporter unit 30 comprises an elongated housing which is connected at one of its ends to the microwave unit over the associated cavity with the housing including four side walls 32, 34, 36 and 38, the side walls being arranged in opposed pairs of such walls with the inner surfaces of the walls being of relatively smooth configura-tion and such ~hat each wall inner surface is in parallel spaced disposition with an opposite side wall inner surface, the con-figuration of housing desirably being generally rectangular. At one end of the housing 30 there is provided a flange 40 with which the housing can be connected to the microwave unit. The ' ~ '. .
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~ 038936 opposite end also includes a flange 42 which can be used for a like purpose, for example, in connecting an input hopper unit 33 at the entrance to the transporter unit.
Disposed within the transporter unit housing are a pair of drums 44 and 46 which provide means for supporting a plurality of endless belts 50 for travel through an endless travel course within the housing, the belts in the depicted embodiment tra-versing straight course runs adjacent to and spaced from opposed side walls, 32 and 34. The belts also may be provided with a series of upstanding lugs 52 at spaced locations along the length of each belt, the plurality of belts further being arranged to travel in generally parallel travel courses within the housing and drum 44 being provided with radial flanges 56 disposed be-tween adjacent ones of the belts to maintain them in such parallel disposition. The drum 44 which is remote from the end of the housing that is connected to the microwave cavity, is a driven unit and for such purpose suitable driving mechanism as at 60 can be provided, the shaft 62 associated with drum 44 being rotatably mounted in the other pair of opposed side walls 36, 38.
Idler drum 46 which also is rotatably supported in the housing desirably is electrically insulated from the structure of the walls 36 and 38 and to that end drum 46 is at the opposite ends provided with bushings 68 of electrically insulative material, as for example, polytetrafluoroethylene or other suitable polymer material which are rotatably received on fixed pins 67 carried on the housing walls, the fixed pins being part of the fixed struc- ~ :
ture generally depicted at 69.
In accordance with the present invention and to reduce a microwave leakage to any but inconsequential values, the housing is provided with pairs of tunnels 70 associated one pair each with one of the belts so that during the straight course run of the belt it will travel through the pair of tunnels, with the tunnels having a rectangular cross section the longest side di-mension of which is not greater than 2 inches. Further the tunnels 70 desirably have a length at least about 10 inches. As can be best seen in Figure 4, the tunnels 70 extend between the -two drums 44, 46 and are comprised of partitions 72 extending ~:
inwardly from the opposed side walls 32, 34 at substantially a right angle therewith with the partitions extending alongside the ~ ~
8traight run courses of the belts. Further panels 74 extend ~ -between the partitions and are disposed substantially parallel to and spaced from the inner surfaces of the walls 32, 34. The . :
belts 50 as can be seen in Figure 4 travel in their straight run courses intermediate the inner surfaces of the side walls 32, 34 :
and the panels 74. As indicated above, the cross sectional con- ` :
figuration and dimension of the tunnel is selected such as to produce a cut-off effect without the use of any special dielectric in order to reduce microwave leakage to levels which are below The transporter unit 30 also is provided with a reflector 80 for reflecting microwaves which said reflector is supported in the housing adjacent drum 46 and adjacent to the side of said drum remote from the end of the housing which is connected to the ~ . .
microwave cavity, with the reflector following closely the contour of the drum 46 and being disposed further in spaced relation there-: -8-with. The reflector extends substantlally the full width of the , housing between the side walls 36, 28.
In order to avoid heating the belts, it is desirable that the belts 50 be provided with a material which has low-loss characteristics and for this purpose material such as polytetra-fluoroethylene, glass fiber and silicone rubber can be used for the belts. The structure of the housing desirably is made from any suitable metal as for example stainless steel or aluminum.
The cross section of the tunnels 70 is as mentioned rectan-gular and can be square rectangular so long as the longest sideof said rectangle is not more than two inches in length.
The protective transporter 30 was employed to feed cut tobacco filler into a microwave cavity charged with 30 Kw at a frequency of 2450 MHz. The feeding went smoothly and leakage ;
from the top opening of the feeder was less than 5 mw/cm , measured at the top of tunnels 70.
Figure 5 depicts a modified form of protective transporter unit 130 in which means are provided for adjusting the tension in each of the respective transporter belts.150. Thus the unit 130 includes tunnels 170a associated with the entry travel course run of the belt to the microwave cavity and tunnels 170b, 170c associated with the return travel course run of the belts, the return travel associated tunnels being disposed at angles as shown relative to the entry travel course run tunnels to permit the belts to traverse a course around the pulleys 179 of tensioning units 180, the tunnels 170b, 170c otherwise being in all respects as to dimension and function, the same as earlier described. The side wall structure 181 of the housing is also disposed at an ~0389;~6 angle to the opposite wall structure 183, the structure 181 being for example provided in sections associated with each tunnel 170b, 170c. Thus each belt can be provided with its own tensioning control device without interferring with the purpose of providing effective cut-off tube means at the microwave cavity end of the unit. .
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Claims (26)
1. In a microwave unit including a casing enclosing a space defining a microwave cavity in which material can be subjected to microwave energy, said casing having an opening therein, protective transporter apparatus for feeding said material to and from said cavity through said opening while preventing any but inconsequential escape of microwave leakage from said cavity, said apparatus comprising an elongated housing connected at one end to said casing and extending outwardly from said casing opening, said housing including two opposed inner wall surfaces, transporter belt means, means for supporting said transporter belt means for travel in an endless travel course within said housing and with oppositely directed straight course runs passing adjacent to and spaced from said inner wall surfaces, and means defining with said inner wall surfaces a pair of tunnels of rectangular cross-section within said housing which said transporter belt means traverse during the respective straight course runs thereof, the longest side dimension of each tunnel cross section being not greater than 2 inches in length, the length of said tunnels being at least about 10 inches.
2. The apparatus of claim 1 in which said transporter belt means comprises a plurality of separate belts each of which tra-verses straight course runs extending parallel with those of the other belts, there being provided a corresponding plurality of pairs of tunnels, each pair being associated with one of said belts.
3. The apparatus of claim 1 in which said tunnels are square-rectangular in cross section.
4. The apparatus of claim 1 in which said transporter belt means is provided with upstanding lugs at spaced locations along the length thereof.
5. The apparatus of claim 1 in which said transporter belt means is made of a material which has low-loss characteris-tics.
6. The apparatus of claim 5 in which said transporter belt means is made of one of polytetrafluoroethylene, glass fiber and silicone rubber.
7. The apparatus of claim 1 in which the said opposed inner wall surfaces are those of a pair of spaced housing side walls, there being a further pair of spaced housing side walls extending between said first-mentioned pair, the means for supporting said transporter belt means comprising a first drum extending between and rotatably supported in said further pair of housing side walls at said one end thereof and adjacent said cavity opening, and a second drum extending between and rotatably supported in said further pair of housing side walls adjacent the other end thereof.
8. The apparatus of claim 7 in which said first drum is electrically insulated from the structure of said housing.
9. The apparatus of claim 7 in which said transporter belt means comprises a plurality of separate belts each of which traverses straight course runs extending parallel with those of the other belts, there being provided a corresponding plurality of pairs of tunnels, each pair being associated with one of said belts, said second drum being provided with radial flanges extend-ing between adjacent ones of said belts for maintaining said belts disposed parallel with the others.
10. In a microwave unit including a casing enclosing a space defining a microwave cavity in which material can be subject-ed to microwave energy, said casing having an opening therein, protector transporter apparatus for feeding said material to and from said cavity, through said opening while preventing any but inconsequential escape of microwave leakage from said cavity, said apparatus comprising an elongated housing connected at one end to said casing and extending outwardly from said casing opening, said housing including a pair of opposed parallel spaced side walls, and a further pair of spaced side walls extending between said first pair of side walls, a plurality of belts, means for supporting said belts for travel in an endless course within said housing and with oppositely directed straight course runs passing adjacent to and spaced from the inner surfaces of the first-mentioned pair of housing side walls, said means including a first drum extending between and rotatably supported in said further pair of side walls at said one end thereof and adjacent said cavity opening, and a second drum extending between and rotatably supported in said further pair of housing side walls adjacent the other end thereof, said second drum being provided with radial flanges extending between adjacent ones of said belts for maintaining said belts disposed parallel one with the others, and means defining with the inner surfaces of said first-mentioned pair of housing side walls, a corresponding plurality of pairs of tunnels of rectangular cross section within said housing associated one pair with each belt and which each said belt traverses during the respective straight run courses thereof, the longest side dimension of each tunnel cross section being not greater than 2 inches in length, said tunnel defining means including partitions extending inwardly from the inner surfaces of the first-mentioned pair of housing side walls alongside the straight run courses of said belts, and panels extending between said partitions and disposed substantial-ly parallel to said inner surfaces, said belt straight run courses being disposed intermediate said panels and said inner surfaces, said partitions and panels extending longitudinally of said hous-ing between said drums for a length of at least about 10 inches.
11. The apparatus of claim 10 further comprising a micro-wave reflector supported in said housing adjacent said first drum adjacent to the side of said first drum remote from said one end of said housing and following the contour of said drum in spaced relation therewith.
12. Apparatus for subjecting a material to microwave energy comprising a casing enclosing a space constituting a microwave cavity, said casing having a first opening through which said material can be introduced to said cavity and a second opening through which said material can be removed from said cavity, microwave energy source means in said casing, means within said casing for conveying material between said first and said second openings, said source means being disposed to direct microwaves at said material during conveyance thereof between said first and second openings, and, protective transporter units connected to said casing and covering the first and second openings therein, each said protective transporter unit comprising an elongated housing connected at one end to said casing and extending out-wardly from the associated casing opening, said housing including two opposed inner wall surfaces, transporter belt means, means for supporting said transporter belt means for travel in an end-less travel course within said housing and with oppositely directed straight course runs passing adjacent to and spaced from said inner wall surfaces, and means defining with said inner wall surfaces a pair of tunnels of rectangular cross-section within said housing which said transporter belt means traverses during the respective straight course runs thereof, the longest side di-mension of each tunnel cross section being not greater than 2 inches in length, the length of said tunnels being at least about 10 inches.
13. The apparatus of claim 2 further comprising means for separately adjusting the tension in each of said belts.
14. A microwave treatment apparatus for treating particulate material by subjecting it to microwave energy, the apparatus comprising a casing enclosing s space defining a microwave cavity, a microwave power source for exciting microwave energy within the casing, and transporters for conveying material to and from said cavity through openings in the casing, each transporter comprising an enclosure comprising a housing having two opposed inner wall surfaces and means defining with the inner wall surfaces a plurality of pairs of straight tunnels of rectangular cross-section within the housing, the tunnels having wave guide characteristics and predetermined cross-sectional dimensions and length such as to effect attenuation of microwave energy therein resulting from operation of the microwave power source to a level below 10mw/cm2 at the tunnel ends remote from the casing opening associated with the transporter, a plurality of separate endless belts, and means for supporting the belts for travel with each belt having two straight runs extending through an associated pair of said tunnels.
15. Apparatus according to claim 14, in which the microwave power source operates at 2450 MHz and with a power output of 30 Kw, the longest side dimension of the tunnel cross-section being substantially 2 inches with each of the tunnels being 10 inches long.
16. Apparatus according to claim 15, in which the tunnels are square in cross-section.
17. Apparatus according to claim 16, in which the endless belts are provided with upstanding lugs at spaced locations along the length thereof.
18. Apparatus according to claim 17, in which the endless belts are made of a material which has low-loss characteristics.
19. Apparatus according to claim 18, in which said endless belts are made of polytetrafluoroethylene, glass fiber or silicone rubber.
20. Apparatus according to claim 19, in which the said opposed inner wall surfaces are those of a pair of spaced housing side walls, there being a further pair of spaced housing side walls extending between said first-mentioned pair, the means for supporting said transporter belt means comprising a first drum extending between and rotatably supported in said further pair of housing side walls at said one end thereof and adjacent said cavity opening, and a second drum extending between and rotatably supported in said further pair of housing side walls adjacent the other end thereof.
21. Apparatus according to claim 20, wherein the various endless belts are each disposed in parallel planes perpendicular to the drum axes.
22. Apparatus according to claim 21, wherein the second drum is provided with radial flanges extending between adjacent ones of the belts for maintaining the alignment of the belts relative one with the other.
23. Apparatus according to claim 20, 21 or 22, in which the first drum is electrically insulated from the structure of the housing.
24. Apparatus according to claim 20, 21 or 22, wherein the tunnel defining means includes partitions extending inwardly within the housing from the inner surfaces of the opposed housing side walls alongside the straight run courses of the belts, and panels extending between the partitions and disposed substantially parallel to said inner surfaces, said straight belt runs being disposed intermediate the panels and the inner surfaces with the partitions and panels extending longitudinally between the drums through said predetermined distance.
25. Apparatus according to claim 20, wherein a microwave reflector is supported in the housing adjacent the first drum adjacent to the side of the first drum remote from the cavity, said reflector following the contour of the drum in spaced relationship thereto.
26. Apparatus according to claim 25, including means for separately adjusting the tension in each of the belts.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US50604274A | 1974-09-16 | 1974-09-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1038936A true CA1038936A (en) | 1978-09-19 |
Family
ID=24012927
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA233,304A Expired CA1038936A (en) | 1974-09-16 | 1975-08-12 | Protective transporter for transporting materials to and from a microwave unit |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5156044A (en) |
| CA (1) | CA1038936A (en) |
| CH (1) | CH614035A5 (en) |
| DE (1) | DE2541112C3 (en) |
| FR (1) | FR2284945A1 (en) |
| GB (1) | GB1490027A (en) |
| SU (1) | SU585804A3 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0014121B1 (en) * | 1979-01-22 | 1987-04-22 | JD-Technologie AG | Microwave heating apparatus |
| NZ246520A (en) * | 1992-01-15 | 1996-11-26 | Scallop Processing Equipment P | Shucking scallops by spraying with hot water prior to eviscerating |
| DE10062633C2 (en) * | 2000-12-15 | 2002-12-05 | Advanced Photonics Tech Ag | Method and device for heating continuously conveyed, lattice-shaped material or similar structures |
| DE10159045B4 (en) * | 2001-10-29 | 2004-01-29 | Johann Haas | Conveying conveyed material with dust [dust (with) conveyance] |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1095428B (en) * | 1959-05-16 | 1960-12-22 | Mikrowellen Ges M B H Deutsche | Continuous microwave oven |
| DE2013627A1 (en) * | 1970-03-21 | 1971-10-14 | Knapsack Ag, 5033 Knapsack | Pastes containing acids, amines and phosphoric acid esters, and processes for their production |
| JPS5122348Y2 (en) * | 1971-06-21 | 1976-06-09 |
-
1975
- 1975-08-12 CA CA233,304A patent/CA1038936A/en not_active Expired
- 1975-08-20 GB GB3465075A patent/GB1490027A/en not_active Expired
- 1975-08-27 CH CH1110175A patent/CH614035A5/en not_active IP Right Cessation
- 1975-08-28 FR FR7526535A patent/FR2284945A1/en active Granted
- 1975-09-05 SU SU752178146A patent/SU585804A3/en active
- 1975-09-12 JP JP11083775A patent/JPS5156044A/en active Pending
- 1975-09-15 DE DE19752541112 patent/DE2541112C3/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| SU585804A3 (en) | 1977-12-25 |
| CH614035A5 (en) | 1979-10-31 |
| FR2284945B1 (en) | 1980-08-08 |
| DE2541112B2 (en) | 1979-07-05 |
| DE2541112A1 (en) | 1976-04-01 |
| GB1490027A (en) | 1977-10-26 |
| FR2284945A1 (en) | 1976-04-09 |
| DE2541112C3 (en) | 1984-10-11 |
| JPS5156044A (en) | 1976-05-17 |
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