CN113411929A

CN113411929A - Waveguide tube for microwave heating device and microwave heating device

Info

Publication number: CN113411929A
Application number: CN202010185154.8A
Authority: CN
Inventors: 邓亘皓; 曹明雄; 陈汉颖
Original assignee: Hongshuo System Co ltd
Current assignee: Hongshuo System Co ltd
Priority date: 2020-03-17
Filing date: 2020-03-17
Publication date: 2021-09-17
Anticipated expiration: 2040-03-17
Also published as: EP3883344B1; EP3883344A1; CN113411929B

Abstract

The invention relates to a waveguide tube of a microwave heating device and the microwave heating device, wherein the microwave heating device comprises a waveguide tube, two microwave transmitting modules and a conveying module; the wave guide tube forms a traveling wave path and is provided with at least one conveying opening pair and at least one wave guide plate pair; the conveying opening pair is provided with two conveying openings which are respectively formed on two opposite side walls of the waveguide tube along a conveying direction; the wave guide plate pair is positioned in the wave guide pipe and is provided with two wave guide plates extending along the traveling wave path, and the two wave guide plates are respectively arranged on the top wall and the bottom wall of the wave guide pipe; the two microwave transmitting modules are respectively arranged at two opposite ends of the waveguide tube; the conveying module penetrates through the conveying opening pair along the conveying direction; by arranging two microwave transmitting modules and the waveguide plate pair, the invention can further improve the uniform heating degree of the high microwave absorbing material in the waveguide tube and can heat the object to be heated with high unit price.

Description

Waveguide tube for microwave heating device and microwave heating device

Technical Field

The present invention relates to a microwave heating device, and more particularly, to a waveguide tube of a microwave heating device and a microwave heating device capable of uniformly heating both a high microwave absorbing material and a low microwave absorbing material.

Background

The microwave heating devices in the prior art can be mainly classified into the following three types:

the principle of the closed resonant cavity is that an object to be heated moves or rotates in the closed resonant cavity so as to reduce the heating nonuniformity of the object to be heated caused by microwave hot spots and cold spots in the resonant cavity.

The principle of the open resonant cavity is similar to that of a closed resonant cavity, and the heated substance passes through a standing wave hot spot in the cavity in a continuous circulation mode to ionize the to-be-heated substance, and the open resonant cavity is mainly applied to light source generation (such as a sulfur lamp) or waste treatment.

The principle of the traveling wave type heater is that a substance to be heated is heated by traveling waves along a microwave transmission path, so that heating nonuniformity caused by the hot spot and cold spot effects of standing waves is avoided.

The closed resonant cavity and the open resonant cavity heat the object to be heated by standing waves, however, the standing waves form distinct hot spots and cold spots in the space and cannot heat the object to be heated uniformly, so that the closed resonant cavity and the open resonant cavity can only be applied to the market with low price in practice, such as wood dehydration or tobacco drying.

The traveling wave heater can not form obvious hot spots and cold spots, so that when the object to be heated is made of the low microwave absorbing material, the traveling wave heater can uniformly heat the object to be heated; however, when the object to be heated is a high microwave absorbing material, the microwave energy is rapidly absorbed by the object to be heated which is close to the heating source, so that the object to be heated which is far from the heating source cannot be sufficiently heated, and the object to be heated cannot be uniformly heated.

Therefore, the microwave heating apparatus of the prior art needs to be improved.

Disclosure of Invention

In view of the above-mentioned drawbacks and disadvantages of the prior art, the present invention provides a waveguide tube of a microwave heating device capable of uniformly heating a high microwave absorbing material and a microwave heating device, so as to solve the problem that an object to be heated cannot be uniformly heated.

In order to achieve the above object, the present invention provides a microwave heating device, comprising:

a waveguide forming a traveling wave path, the waveguide having:

at least one heating section having:

a front opening wall;

a rear opening wall spaced from the front opening wall in a transport direction;

a top wall connecting said front opening wall and said rear opening wall;

a bottom wall connecting the front opening wall and the rear opening wall and disposed opposite the top wall;

at least one conveying opening pair having two conveying openings formed in the front opening wall and the rear opening wall of the at least one heating section, respectively;

at least one wave guide plate pair arranged in the at least one heating section, wherein the position of the at least one wave guide plate relative to the traveling wave path corresponds to the position of the at least one conveying opening relative to the traveling wave path; the at least one wave guide plate pair comprises: two wave guide plates respectively connected to the top wall and the bottom wall of the at least one heating section and extending along the traveling wave path; the two wave guide plates are both made of dielectric materials;

the two microwave emission modules are respectively arranged at two opposite ends of the waveguide along the traveling wave path;

and the conveying module penetrates through the at least one conveying opening pair of the waveguide tube along the conveying direction.

Further, each of the delivery openings of the waveguide has a top side circumference and a bottom side circumference, and the distance between the top side circumference and the bottom side circumference defines the opening width of the delivery opening; the opening width of each of the transport openings along opposite ends of the traveling wave path is reduced.

Further, each of the delivery openings of the waveguide has a centerline, and the top side circumference and the bottom side circumference of each of the delivery openings are respectively formed on both sides of the centerline;

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

two first upper straight line segments located on opposite sides of the top body segment along the traveling wave path, respectively;

the bottom side periphery of each of the delivery openings has:

a bottom body segment extending along the traveling wave path;

two first lower straight line segments located on opposite sides of the bottom body segment along the traveling wave path, respectively;

the first upper straight line section and the first lower straight line section at either end of the two opposite ends of the traveling wave path of each conveying opening respectively extend towards the middle line, and the tail end of the first upper straight line section is connected with the tail end of the first lower straight line section.

Further, a second upper straight line section is formed on the periphery of the top side of each conveying opening at two opposite ends of the conveying opening, and the second upper straight line section is located between the corresponding first upper straight line section and the top main body section;

a second lower straight line section is formed on the periphery of the bottom side of each conveying opening at two opposite ends of the conveying opening respectively, and the second lower straight line section is located between the corresponding first lower straight line section and the corresponding bottom main body section;

the included angle between the first upper straight line segment and the central line is larger than the included angle between the extension line of the second upper straight line segment and the central line, and the included angle between the first lower straight line segment and the central line is larger than the included angle between the extension line of the second lower straight line segment and the central line.

Further, each of the delivery openings of the waveguide has a centerline, and the top side circumference and the bottom side circumference of each of the delivery openings are formed on both sides of the centerline;

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

two first upper arc segments located on opposite sides of the top body segment along the traveling wave path, respectively;

the bottom side periphery of each of the delivery openings has:

a bottom body segment extending along the traveling wave path;

two first lower arc segments located on opposite sides of the bottom body segment along the traveling wave path, respectively;

the first upper arc line segment and the first lower arc line segment at any one end of the two opposite ends of the traveling wave path of each conveying opening respectively extend towards the center line, and the tail end of the first upper arc line segment is connected with the tail end of the first lower arc line segment.

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

two upper step sections located on opposite sides of the top body section along the traveling wave path, respectively;

the bottom side periphery of each of the delivery openings has:

a bottom body section disposed opposite the top body section;

two lower step sections located on opposite sides of the bottom body section along the traveling wave path, respectively;

wherein the upper step section and the lower step section at either end of the opposite ends of each of the delivery openings along the traveling wave path extend toward the centerline, respectively, and ends of the upper step section are connected to ends of the lower step section.

Further, the plate body thickness of the opposite ends of each wave guide plate of the at least one wave guide plate pair is reduced.

Furthermore, one side of each wave guide plate, which is connected with the wave guide tube, is provided with an abutting plane, and the abutting plane extends along the traveling wave path; the other side of the wave guide plate is provided with:

a body surface extending along the traveling wave path, the body surface having a length in the traveling wave path that is less than a length of the abutment plane in the traveling wave path;

the two first inclined planes are respectively positioned on two opposite sides of the main body surface along the traveling wave path, and extend to the attaching plane from two opposite sides of the main body surface respectively so as to form two opposite end edges of the wave guide plate along the traveling wave path.

Furthermore, each wave guide plate is also provided with two second inclined planes, and each second inclined plane is positioned between one first inclined plane and the main body surface;

the inclination degree of the second inclined surface of each wave guide plate relative to the abutting plane is smaller than that of the first inclined surface relative to the abutting plane.

a body surface extending along said traveling wave path, said body surface having a length along said traveling wave path that is less than a length of said abutment plane along said traveling wave path;

the two cambered surfaces are respectively positioned on two opposite sides of the main body surface along the traveling wave path, and extend to the attaching plane from two opposite sides of the main body surface respectively so as to form two opposite end edges of the wave guide plate along the traveling wave path.

two ladder faces, it is located respectively the main part face is followed the relative both sides on travelling wave route, two ladder faces are respectively certainly the relative both sides of main part face extend to paste the plane, in order to form the wave guide plate is followed two relative edges of holding of travelling wave route.

Further, the microwave heating device is also provided with an air exhaust module which is communicated with the internal space of the waveguide tube; the outside cladding of module of bleeding has a zone of heating.

Further, the air extraction module is provided with a water collecting tank.

Further, the microwave heating device also has at least one microwave isolation module, which has:

the seat body is connected with the waveguide tube and forms a channel which surrounds the outside of the conveying module and is communicated with one conveying opening of the waveguide tube;

the microwave suppression pieces penetrate through the outer side surface of the seat body; each microwave suppressing member is a pipe body, two ends of the microwave suppressing member are respectively a closed end and an open end, the open end protrudes out of the base body, and the closed end is located in the channel.

Further, the direction of the microwave electric field between the two wave guide plates of the at least one wave guide plate pair is parallel to the conveying direction.

In order to achieve the above object, the present invention further provides a waveguide of a microwave heating apparatus, comprising:

at least one heating section having:

a front opening wall;

a rear opening wall spaced from the front opening wall in the conveying direction;

a top wall connecting said front opening wall and said rear opening wall;

at least one conveying opening pair having two elongated conveying openings extending along a traveling wave path, the two conveying openings being formed in the front opening wall and the rear opening wall of the at least one heating section, respectively;

at least one wave guide plate pair arranged in the wave guide pipe, wherein the position of the at least one wave guide plate in the length direction of the wave guide pipe corresponds to the position of the at least one conveying opening in the length direction of the wave guide pipe; the at least one wave guide plate pair comprises:

two wave guide plates respectively connected to the top wall and the bottom wall of the at least one heating section and extending along the traveling wave path; the two wave guide plates are both made of dielectric materials.

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

the bottom side periphery of each of the delivery openings has:

a bottom body segment extending along the traveling wave path;

Further, in the present invention,

a second upper straight line section is formed on the periphery of the top side of each conveying opening at two opposite ends of the conveying opening respectively, and the second upper straight line section is positioned between the corresponding first upper straight line section and the top main body section;

a second lower straight line section is formed on the periphery of the bottom side of each conveying opening at two opposite ends of the conveying opening, and the second lower straight line section is located between the corresponding first lower straight line section and the corresponding bottom main body section;

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

the bottom side periphery of each of the delivery openings has:

a bottom body segment extending along the traveling wave path;

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

the bottom side periphery of each of the delivery openings has:

a bottom body section disposed opposite the top body section;

Furthermore, each wave guide plate is also provided with two second inclined planes, and each second inclined plane is positioned between one first inclined plane and the main body surface; the inclination degree of the second inclined surface of each wave guide plate relative to the abutting plane is smaller than that of the first inclined surface relative to the abutting plane.

a body surface extending along the traveling wave path, the body surface having a length along the traveling wave path that is less than a length of the abutment plane along the traveling wave path;

The invention has the following advantages:

firstly, an object to be heated is conveyed by the conveying module to pass through the waveguide tube and is heated in the waveguide tube by microwaves emitted by the microwave emitting modules.

Second, by further providing a pair of wave guides made of a dielectric material in the wave guide, the present invention can process a material having a strong microwave absorption property and an object to be heated having a metal object, thereby improving a range of heatable materials of the present invention, and thus can process a high-price object to be heated, which cannot be processed by a conventional microwave heating apparatus, such as a wet circuit board, various electronic products containing metal components, a semiconductor wafer containing metal, a solar wafer containing metal wires, and wet clothes having metal fittings, thereby increasing the production value of the present invention.

Drawings

Fig. 1 is a perspective external view of a first embodiment of a microwave heating apparatus of the present invention.

Fig. 2 is a partially exploded view of a first embodiment of the microwave heating apparatus of the present invention.

Fig. 3 is another partially exploded view of the first embodiment of the microwave heating device of the present invention.

Fig. 4 is a schematic partial cross-sectional view of the components of a first embodiment of the microwave heating apparatus of the present invention.

Fig. 5 is a schematic cross-sectional view of a heating section in a first embodiment of the microwave heating apparatus of the present invention.

Fig. 6 is a schematic front view of a heating section in a first embodiment of the microwave heating apparatus of the present invention.

Fig. 7 is a schematic front view of a heating section in a second embodiment of the microwave heating apparatus of the present invention.

Fig. 8 is a partially enlarged view of fig. 7.

Fig. 9 is a schematic front view of a heating section in a third embodiment of the microwave heating apparatus of the present invention.

Fig. 10 is a schematic front view of a heating section in a fourth embodiment of the microwave heating apparatus of the present invention.

Fig. 11 is a schematic sectional view of a microwave heating apparatus according to a first embodiment of the present invention, showing a microwave suppressing member.

Fig. 12 is a perspective view of a waveguide of a fifth embodiment of the microwave heating apparatus according to the present invention.

Fig. 13 is an exploded view of the waveguide of the fifth embodiment of the microwave heating apparatus of the present invention.

Fig. 14 is a schematic sectional view of a waveguide tube according to a fifth embodiment of the microwave heating apparatus of the present invention.

Fig. 15 is a microwave electric field distribution diagram at the waveguide of fig. 5.

FIG. 16 is a graph of reflection coefficient versus frequency for mode-switched impedance matching of a waveguide of the present invention versus section of a waveguide plate.

FIG. 17 is a graph of transmission coefficient versus frequency for mode-switched impedance matching of a waveguide to a segment of a waveguide plate in accordance with the present invention.

Reference numerals and description:

10. a waveguide tube; 10D, a waveguide; 11. a heating section; 111. a front opening wall; 112. a rear opening wall; 113. a top wall; 114. a bottom wall; 12. a communicating section; 13. a pair of delivery openings; 131. a delivery opening; 131B, a delivery opening; 131C, a delivery opening; 131D, a delivery opening; 1311. a midline; 1311A, midline; 1312. a top side periphery; 1313. a bottom side periphery; D. a direction of conveyance; 14. a wave guide plate pair; 14D, a wave guide plate pair; 141. a wave guide plate; 141A, a wave guide plate; 141B, a wave guide plate; 141C, a wave guide plate; 141D, a wave guide plate; 15D, block body; 16D, a mounting end; 17D, a guide ring wall; 171D, a shielding surface; 20. a microwave transmitting module; 21. a microwave source; 22. a circulator; 23. a directional coupler; 24. a water loader; 30. a delivery module; 40. an air extraction module; 41. a tube assembly; 42. A heating layer; 43. a water collection tank; 50. a microwave isolation module; 51. a base body; 511. a channel; 52. a microwave suppression component; 521. a closed end; 522. an open end; 53. an isolation flange; 61. a top main body section; 61A, a top body segment; 62. A bottom body section; 62A, a bottom body section; 63. a first upper straight line segment; 63A, a first upper straight line segment; 63B, a first upper arc segment; 64. a first lower straight line segment; 64A, a first lower straight line segment; 64B, a first lower arc segment; 64C, a lower step section; 65A, a second upper straight line segment; 66A, a second lower straight line segment; 71. a flat surface is attached; 71A, an abutting plane; 71B, an abutting plane; 71C, an abutting plane; 72. a main body surface; 72A, a main body surface; 72B, a main body surface; 72C, main body surface; 73. a first inclined plane; 73A, a first inclined plane; 73B, an arc surface; 73C, a step surface; 73D, a first bevel; 74A, a second bevel; 74D, a second bevel; theta 1, an included angle between the first upper straight line segment and the central line; theta 2, and an included angle between the extension line of the second upper straight line segment and the central line; theta 3, an included angle between the normal of the second inclined plane and the normal of the attaching plane; theta 4, and the included angle between the normal line of the first inclined plane and the normal line of the abutting plane.

Detailed Description

The technical means adopted by the invention to achieve the preset purpose are further described below by combining the accompanying drawings and the preferred embodiments of the invention.

Referring to fig. 1 to 4, the microwave heating apparatus of the present invention includes a waveguide 10, two microwave emitting modules 20 and a conveying module 30; in the embodiment, the microwave isolation module further includes an air pumping module 40 and a microwave isolation module 50.

The waveguide 10 in this embodiment is formed by connecting a plurality of heating sections 11 and a plurality of communicating sections 12, the heating sections 11 are arranged in parallel and in sequence along a conveying direction D, and the communicating sections 12 are connected between two adjacent heating sections 11; in the present embodiment, the heating section 11 is a straight pipe, the connection section 12 is a bent pipe, the heating section 11 and the connection section 12 form the waveguide 10 into a substantially S-shaped pipe, and form the waveguide 10 into an S-shaped traveling wave path, but the waveguide 10 may be any pipe having openings at both ends thereof communicated with each other, and for example, the waveguide 10 may be only the heating section 11 having a straight pipe shape. The two microwave emitting modules 20 are respectively disposed at two opposite ends of the waveguide 10 along the traveling wave path, and the waveguide 10 transmits the microwaves emitted by each microwave emitting module 20 from one end of the waveguide 10 to the other end of the waveguide 10 along the traveling wave path, so that even if the distance between an object (not shown) to be heated in the waveguide 10 and one of the microwave emitting modules 20 is different, the heating power of each object to be heated by the microwave emitting module 20 is different, and the difference can be complemented with the other microwave emitting module 20, so that the total heating power of each object to be heated is more uniform. Specifically, if the percentage of microwave energy absorbed by the material to be heated is defined as the usage efficiency (%), the maximum value (P) of microwave energy is absorbed by the material to be heated along the traveling wave path_max) Minus a minimum value (P)_min) Divided by the mean value (P)_average) Uniformity is defined as, i.e., uniformity (%) is:

from the calculation results of table 1, it can be seen that: the use of two microwave emitter modules 20 can greatly improve the uniformity of heating at the same efficiency of use.

Table 1: the relationship between the uniformity and the efficiency of the single microwave emitting module 20 and the dual microwave emitting module 20 is as follows:

in the embodiment, the microwave emitting module 20 emits microwave with a frequency of 2450 mhz toward the waveguide 10, and the cross-sectional shape of the waveguide 10 matches the microwave with the frequency, and the cross-sectional shape is a WR340 rectangular cross-section defined by Electronic Industry Alliance (EIA), which enables the microwave to operate in TE10 mode to reduce complexity, but the frequency of the microwave emitted by the microwave emitting module 20 is not limited to 2450 mhz.

In addition, each microwave emitting module 20 in the present embodiment includes a microwave source 21, a circulator 22, a directional coupler 23, and a water loader 24. The microwave source 21 and the directional coupler 23 are respectively located at two ends of the microwave emitting module 20, the circulator 22 is connected with the microwave source 21 and the directional coupler 23, the water loader 24 is connected with one side surface of the circulator 22, and the directional coupler 23 is connected with one end of the waveguide 10. The circulator 22 utilizes the gyromagnetic phenomenon to control the microwave to be transmitted in a specific direction, thereby protecting the microwave source 21. The directional coupler 23 can measure the microwave power transmitted by the microwave transmitting module 20 toward the waveguide 10, and measure the microwave power transmitted by the waveguide 10 toward the microwave transmitting module 20.

Referring to fig. 3, 5 and 6, each heating section 11 of the waveguide 10 is formed with a conveying opening pair 13, each conveying opening pair 13 has two conveying openings 131 extending along the traveling wave path, and the two conveying openings 131 are respectively formed on two opposite side walls of the corresponding heating section 11 along a conveying direction D; specifically, each heating section 11 of the waveguide 10 has a front opening wall 111, a rear opening wall 112, a top wall 113 and a bottom wall 114, and the front opening wall 111 and the rear opening wall 112 are spaced apart in the conveying direction D; the top wall 113 and the bottom wall 114 are both connected to the front opening wall 111 and the rear opening wall 112, the top wall 113 and the bottom wall 114 are disposed opposite to each other, and the two conveying openings 131 of the conveying opening pair 13 of each heating section 11 are respectively formed on the front opening wall 111 and the rear opening wall 112 of the heating section 11.

The transport module 30 described above penetrates the pair of transport openings 13 of the waveguide 10 in the transport direction D. The conveying module 30 is preferably a conveyor belt, and the object to be heated is sequentially passed through the heating sections 11 of the waveguide 10 by the pair of conveying openings 13 in the conveying direction D, and the object to be heated is heated by absorbing the microwave energy emitted from the microwave emitting module 20 while passing through the heating sections 11.

In the present embodiment, each of the delivery openings 131 of the waveguide 10 has a central line 1311, a top peripheral edge 1312 and a bottom peripheral edge 1313, the top peripheral edge 1312 and the bottom peripheral edge 1313 are respectively formed on two sides of the central line 1311, and the distance between the top peripheral edge 1312 and the bottom peripheral edge 1313 is defined as the opening width of the delivery opening 131; the opening widths of the two opposite ends of each of the feeding openings 131 along the traveling wave path are respectively reduced, so that the impedance matching effect of the microwaves in the waveguide 10 on the transmission path can be improved, and the object to be heated in the waveguide 10 can be heated more uniformly.

The specific shapes of the opposite ends of each delivery opening 131 are as follows: the top peripheral edge 1312 of each delivery opening 131 has a top body section 61 and two upper necked-down sections, the top body section 61 extending along the traveling wave path, the two upper necked-down sections being connected to opposite sides of the top body section 61 along the traveling wave path. The bottom side peripheral edge 1313 of each delivery opening 131 has a bottom body section 62 and two lower necked-down sections, the bottom body section 62 extending along the traveling wave path, the two lower necked-down sections being located on opposite sides of the bottom body section 62 along the traveling wave path. The upper and lower converging sections at either end of the opposite ends of the traveling wave path of each transport opening 131 extend toward the corresponding centerline 1311, respectively, and the ends of the upper and lower converging sections are connected to form the ends of the transport opening 131. To further adjust the impedance matching, the shape of the upper and lower necking sections may be one of four:

1. linear gradual change: each necking section (i.e., the upper necking section and the lower necking section) is a straight line, i.e., each upper necking section is a first upper straight line section 63, and each lower necking section is a first lower straight line section 64.

2. Multi-fold structure: each necking section (i.e., the upper necking section and the lower necking section) has more than two connected straight line segments, for example, in the second embodiment of the present invention (as shown in fig. 7 and 8), each upper necking section has a first upper straight line segment 63A and a second upper straight line segment 65A, the second upper straight line segment 65A is located between the corresponding first upper straight line segment 63A and the top main body segment 61A, and an included angle θ 1 between the first upper straight line segment 63A and the central line 1311A is greater than an included angle θ 2 between an extension line of the second upper straight line segment 65A and the central line 1311A; each of the lower necking sections has a first lower straight line section 64A and a second lower straight line section 66A, the second lower straight line section 66A is located between the corresponding first lower straight line section 64A and the bottom body section 62A, and an included angle between the first lower straight line section 64A and the central line 1311A is larger than an included angle between an extension line of the second lower straight line section 66A and the central line 1311A. The first upper straight line segment 63A is connected to the end of the second upper straight line segment 65A extending toward the center line 1311A. In this embodiment, the length of each straight line segment and the included angle between the straight line segment and the central line 1311A may be designed according to the theory of Chebyshev Multi-section Matching Transformer (Chebyshev Multi-section Matching Transformer), so as to obtain the best Matching effect within the range of the frequency band in the premise of reducing the size of the system.

3. Curvature gradual change: each of the throat sections (i.e., the upper throat section and the lower throat section) is an arc, such as the third embodiment of the present invention (as shown in fig. 9), each of the upper throat sections is a first upper arc section 63B, and the first upper arc section 63B preferably protrudes toward the outside of the delivery opening 131B; each of the lower necking sections is a first lower arc section 64B, and the first lower arc section 64B preferably protrudes toward the outside of the conveying opening 131B.

4. Step structure: each of the throat sections (i.e., the upper throat section and the lower throat section) is stepped, for example, in the fourth embodiment of the present invention (as shown in fig. 10), each of the upper throat sections is an upper stepped section 63C, each of the lower throat sections is a lower stepped section 64C, and the distance between the upper stepped section 63C and the lower stepped section 64C decreases in a direction away from the center of the conveying opening 131C. In this embodiment, each step section forms a plurality of right angles, but each step section may form only one right angle. The size of each step can be designed according to the theory of the Chebyshev impedance matching converter, so that the optimal matching effect can be obtained within the range of the use frequency band on the premise of achieving the purpose of reducing the size of the system.

In the above embodiments, the shapes and positions of the upper and lower necking sections of the conveying openings 131 are symmetrical to each other, but not limited thereto.

Referring to fig. 3, 5 and 6, in the first embodiment of the present invention, the waveguide 10 further includes a plurality of waveguide plate pairs 14 respectively disposed in each heating section 11, that is, each of the conveying opening pairs 13 is correspondingly disposed with one waveguide plate pair 14. The positions of the waveguide plate pairs 14 on the traveling wave path correspond to the positions of the pairs of transport openings 13 on the traveling wave path in the same heating section 11. Each wave guide plate pair 14 includes two wave guide plates 141, the two wave guide plates 141 are respectively connected to the top wall 113 and the bottom wall 114 of the heating section 11, and both wave guide plates 141 extend along the traveling wave path. The material of the waveguide plate 141 is a dielectric material, and is preferably alumina ceramic, but not limited thereto, and the material of the waveguide plate 141 may also be aluminum nitride ceramic or boron nitride ceramic having better thermal conductivity than alumina ceramic. The waveguide pair 14 can modulate the traveling wave mode of the microwave in the waveguide 10 from the original fundamental mode TE10 to a specific higher-order mode, so as to have the following effects:

first, when the microwave absorbing property of the object to be heated is strong, the pair of wave guide plates 14 can uniformly heat the object to be heated.

Second, once a metal object appears in the conventional waveguide, the microwave in the waveguide is completely reflected by the metal object to the incident end (i.e., the impedance is lost), so that the conventional waveguide cannot heat the object to be heated containing metal at all. In the waveguide 10 of the present embodiment, even if a metal object is mixed with the object to be heated, the microwave can pass around the metal object as usual and uniformly heat the object to be heated.

By providing the pair of wave guide plates 14, the present invention can treat the material having strong microwave absorption property and the object to be heated having a metal object, thereby improving the range of the material which can be heated in the present invention, and thus can treat the objects to be heated having high unit price which cannot be treated by the conventional microwave heating apparatus, such as a wet circuit board, various electronic products containing metal components, semiconductor wafers containing metal, solar wafers containing metal wires, and wet clothes having metal fittings, thereby increasing the value of the present invention.

In the present embodiment, the correspondence between the positions of the wave guide plate pair 14 and the conveying opening pair 13 specifically means: the center of mass of each waveguide plate 141 in each heating stage 11 and the center of shape of each transport opening 131 are all located on the same plane, but not limited to this, it is sufficient if the position of each waveguide plate 141 is substantially the same as the position of each transport opening 131, so that the waveguide plate 141 can adjust the impedance matching of the waveguide 10, and the object to be heated passing through the waveguide 10 can be uniformly heated.

Specifically, in the traveling wave heating method, the magnitude of the microwave energy in the heating material in the traveling direction is P_propagation(z)＝P₀e^-αzThe material absorbs energy in a unit distance along the traveling direction of the microwave, and the energy absorption amount is P_absorption(z)＝αP₀e^-αzIn which P is₀For the initial incident energy, α is the attenuation coefficient, and the value of α is determined by the frequency of the traveling wave and the mode used, in addition to the dielectric constant and dielectric loss of the material.

Referring to fig. 5, 15 and 16, the pair of waveguides 14 made of dielectric material is added to the waveguide 10, so that the pair of waveguides 14 converts the traveling wave mode from the original fundamental mode TE10 to the parallel electric field mode of a higher-order mode in the TE mode; in the parallel electric field mode, the microwave electric field direction is parallel to the conveying direction D. Specifically, the traveling wave mode between the two wave guides 141 of the wave guide pair 14 is completely converted from the fundamental mode TE10 to the TE mode as shown in fig. 15, and the corresponding impedance-matched reflection S11 parameter (i.e., reflection coefficient) versus frequency is shown in fig. 16, wherein the abscissa of fig. 16 is given in gigahertz (Ghz) and the ordinate is given in dB. In addition, as shown in FIG. 17, the relationship between the transmission S21 parameter (i.e., transmission coefficient) and the frequency corresponding to the TE mode impedance matching converted from the fundamental mode TE10 to the TE mode of FIG. 15 is 0dB in all frequency bands.

The advantage of converting the traveling wave mode from the original fundamental mode TE10 to the parallel electric field mode is that the attenuation coefficient α can be modulated, so that even if the microwave absorption characteristic of the object to be heated is strong, the wave guide plate pair 14 can still uniformly heat the object to be heated, and the problem that the existing microwave heating device can only heat the front edges of two ends of the object to be heated is improved; in addition, the parallel electric field mode allows the microwaves to bypass the metal object, and therefore, even if the metal object is mixed with the object to be heated, the microwaves can bypass the metal object to uniformly heat the object to be heated as usual.

In addition, in the present embodiment, the plate thicknesses of the two opposite ends of each waveguide plate 141 are reduced toward the center away from the waveguide plate 141 to further improve the impedance matching, and in order to further adjust the impedance matching, the plate thicknesses of the two opposite ends of the waveguide plate 141 are reduced in a manner similar to that of the two opposite ends of the transmission opening 131, which has four variations:

1. linear gradual change: the opposite ends of each waveguide 141 are specifically shaped as follows, as shown in fig. 6, wherein the side of the waveguide 10 connected to the waveguide 141 has a flat abutment surface 71, and the flat abutment surface 71 extends along the traveling wave path; the other side of the wave guide plate 141 is provided with a main body surface 72 and two first inclined surfaces 73, the main body surface 72 extends along the traveling wave path, and the length of the main body surface 72 along the traveling wave path is smaller than that of the abutting plane 71 along the traveling wave path; the two first inclined surfaces 73 extend from two opposite sides of the main body surface 72 to the abutting plane 71 respectively to form two opposite end edges of the wave guide plate 141 along the traveling wave path. In the present embodiment, the sectional shape of the wave guide plate 141 is an isosceles trapezoid as viewed from the conveying direction D.

2. Multi-fold structure: referring to fig. 7 and 8, in the second embodiment of the present invention, the structure of the wave guide plate 141A with the multi-fold structure at both ends is substantially the same as that of the wave guide plate 141 with the linearly tapered structure at both ends, and the difference is that the wave guide plate 141A further has two second inclined planes 74A, and each second inclined plane 74A is located between one of the first inclined planes 73A and the main body plane 72A; the second inclined surface 74A of each wave guide plate 141A is inclined to the abutment plane 71A to a lesser extent than the first inclined surface 73A is inclined to the abutment plane 71A, i.e., the angle θ 3 between the normal of the second inclined surface 74A and the normal of the abutment plane 71A is smaller than the angle θ 4 between the normal of the first inclined surface 73A and the normal of the abutment plane 71A. In addition, in other preferred embodiments, a plurality of slopes with different slopes may be connected between the first slope 73A and the main body surface 72A, so that a plurality of folding points are formed on the edge of the wave guide plate in this embodiment. In addition, the size of each inclined plane can be designed according to the theory of the Chebyshev impedance matching converter so as to achieve the optimal matching effect.

3. Curvature gradual change: referring to fig. 9, in the third embodiment of the present invention, the wave guide plate 141B with gradually changing curvatures at two ends has substantially the same structure as the wave guide plate 141 with linearly changing curvatures at two ends, and the difference is that the two arc surfaces 73B are respectively located at two opposite sides of the main body surface 72B along the traveling wave path, and the two arc surfaces 73B respectively extend from two opposite sides of the main body surface 72B to the contact plane 71B to form two opposite end edges of the wave guide plate 141B along the traveling wave path. The arc surface 73B preferably protrudes toward the outside of the wave guide plate 141B.

4. Step structure: referring to fig. 10, in the fourth embodiment of the present invention, the wave guide plate 141C with two stepped ends has substantially the same structure as the wave guide plate 141 with two linearly tapered ends, and the difference is that two stepped surfaces 73C are respectively located at two opposite sides of the main body surface 72C along the traveling wave path, and the two stepped surfaces 73C respectively extend from the two opposite sides of the main body surface 72C to the contact plane 71C to form two opposite end edges of the wave guide plate 141C along the traveling wave path. In the present embodiment, each stepped surface 73C is formed with a plurality of straight corner portions, but each stepped surface 73C may be formed with only one straight corner portion. The size of each step surface 73C can be designed according to the chebyshev impedance matching transformer theory to achieve the best matching effect.

Referring to fig. 1, 2 and 5, the air-extracting module 40 is connected to the inner space of the waveguide 10 to extract the water vapor released from the wet object to be heated; the air-extracting module 40 comprises a pipe assembly 41, a heating layer 42 and a water collecting tank 43; the tube assembly 41 is disposed above the waveguide 10 and communicates with the internal space of the waveguide 10; the heating layer 42 is coated outside the tube assembly 41 to prevent the water vapor from condensing and flowing back into the waveguide 10; the water collection tank 43 is connected to one end of the tube assembly 41 opposite to the waveguide 10 to collect water condensed from water vapor in the waveguide 10.

Referring to fig. 1, fig. 5 and fig. 11, the microwave isolation module 50 has two seat bodies 51, a plurality of microwave suppressing members 52 and a plurality of isolation flanges 53; the two seat bodies 51 are respectively connected with the heating sections 11 on two opposite sides of the waveguide tube 10 along the conveying direction D; the base 51 forms a passage 511, the passage 511 surrounds the outside of the conveying module 30 and communicates with a conveying opening 131 of the connected heating section 11 facing outwards. The microwave suppressing element 52 is disposed through the top surface of the base 51, each microwave suppressing element 52 is a tube, two ends of the microwave suppressing element 52 are respectively a closed end 521 and an open end 522, the open end 522 protrudes from the top surface of the base 51, and the closed end 521 is located in the passage 511. The microwave inhibitor 52 can limit the microwave passing through the passage 511, thereby preventing the microwave of the waveguide 10 from leaking to the outside from the delivery opening 131. The microwave suppression element 52 is not limited to be inserted through the top surface of the seat body 51, and may be inserted through any outer side surface of the seat body 51. A plurality of isolation flanges 53 are respectively connected between two adjacent heating sections 11, and two opposite openings of the isolation flanges 53 respectively communicate with the conveying openings 131 of the two heating sections 11 facing each other, so as to avoid microwave leakage.

Finally, referring to fig. 12 to 14, in the fifth embodiment of the present invention, the waveguide 10D is a linear tube formed by combining two blocks 15D, two ends of the linear tube are respectively the mounting ends 16D of the microwave transmitting modules 20, the waveguide 10D is provided with a waveguide pair 14D having a multi-fold structure, and each waveguide 141D of the waveguide pair 14D has a first inclined surface 73D and a second inclined surface 74D. The outer periphery of each delivery opening 131D further protrudes outward to form a guiding annular wall 17D, the guiding annular wall 17D surrounds the delivery opening 131D and forms a shielding surface 171D, and the shielding surface 171D shields the two opposite ends of the delivery opening 131D to reduce microwave leakage.

Referring to fig. 1 and 5, when the present invention is used, an object to be heated is placed at one end of the conveying module 30, the conveying module 30 drives the object to be heated to move along the conveying direction D, so that the object to be heated penetrates into the waveguide 10 through the conveying opening 131, and the waveguide 10 absorbs microwave energy to be heated. When the present invention is used for dehydrating moist objects to be heated by heating, the air extraction module 40 extracts and stores water vapor released from the objects to be heated in the water collection tank 43.

In summary, the present invention improves the uniformity of the heat of the high microwave absorbing material in the waveguide 10 by providing one microwave emitting module 20 at each of the opposite ends of the waveguide 10, and enables the heat treatment of the object to be heated at a high price.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A microwave heating apparatus, comprising:

a waveguide forming a traveling wave path, the waveguide having:

at least one heating section having:

a front opening wall;

a top wall connecting said front opening wall and said rear opening wall;

a bottom wall connecting the front opening wall and the rear opening wall and disposed opposite the top wall; at least one conveying opening pair having two conveying openings formed in the front opening wall and the rear opening wall of the at least one heating section, respectively;

2. A microwave heating apparatus as in claim 1 wherein each of the delivery openings of the waveguide has a top side perimeter and a bottom side perimeter, the distance between the top side perimeter and the bottom side perimeter defining the opening width of the delivery opening; the opening width of each of the transport openings along opposite ends of the traveling wave path is reduced.

3. A microwave heating apparatus according to claim 2,

each delivery opening of the waveguide tube is provided with a midline, and the top side periphery and the bottom side periphery of each delivery opening are respectively formed at two sides of the midline;

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

two first upper straight line segments located on opposite sides of the top body segment along the traveling wave path, respectively; the bottom side periphery of each of the delivery openings has:

a bottom body segment extending along the traveling wave path;

4. A microwave heating apparatus according to claim 3,

5. A microwave heating apparatus as in claim 2 wherein each of the delivery openings of the waveguide has a centerline, and the top and bottom side peripheries of each of the delivery openings are formed on either side of the centerline;

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

two first upper arc segments located on opposite sides of the top body segment along the traveling wave path, respectively; the bottom side periphery of each of the delivery openings has:

a bottom body segment extending along the traveling wave path;

6. A microwave heating apparatus according to claim 2,

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

two upper step sections located on opposite sides of the top body section along the traveling wave path, respectively; the bottom side periphery of each of the delivery openings has:

a bottom body section disposed opposite the top body section;

7. A microwave heating apparatus as in claim 1 wherein the plate body thickness of each of the waveguiding plates of the at least one pair is reduced at opposite ends thereof.

8. A microwave heating apparatus as in claim 7 wherein the side of each waveguide plate to which the waveguide is connected has an abutting plane, the abutting plane extending along the traveling wave path; the other side of the wave guide plate is provided with:

9. A microwave heating apparatus as in claim 8 wherein each of said waveguide plates further has two second inclined surfaces, each of said second inclined surfaces being located between one of said first inclined surfaces and said body surface;

10. A microwave heating apparatus as in claim 7 wherein the side of each waveguide plate to which the waveguide is connected has an abutting plane, the abutting plane extending along the traveling wave path; the other side of the wave guide plate is provided with:

11. A microwave heating apparatus as in claim 7 wherein the side of each waveguide plate to which the waveguide is connected has an abutting plane, the abutting plane extending along the traveling wave path; the other side of the wave guide plate is provided with:

12. A microwave heating apparatus according to any one of claims 1 to 11, wherein the microwave heating apparatus further has a pumping module which communicates with an inner space of the waveguide; the outside cladding of module of bleeding has a zone of heating.

13. A microwave heating apparatus as in claim 12 wherein the pumping module has a water collection tank.

14. A microwave heating apparatus as in any of claims 1 to 11 further comprising at least one microwave isolation module having:

15. A microwave heating apparatus as in any of claims 1 to 11 wherein the direction of the microwave electric field between the two waveplates of the at least one pair of waveplates is parallel to the conveying direction.

16. A waveguide tube for a microwave heating apparatus, comprising:

at least one heating section having:

a front opening wall;

a top wall connecting said front opening wall and said rear opening wall;

17. A waveguide for a microwave heating device according to claim 16 wherein each of the delivery openings of the waveguide has a top perimeter and a bottom perimeter, the distance between the top perimeter and the bottom perimeter defining the opening width of the delivery opening; the opening width of each of the transport openings along opposite ends of the traveling wave path is reduced.

18. A waveguide for a microwave heating apparatus as in claim 17, wherein each of the delivery openings of the waveguide has a centerline, and the top side circumference and the bottom side circumference of each of the delivery openings are formed on both sides of the centerline, respectively;

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

a bottom body segment extending along the traveling wave path;

19. A waveguide tube for a microwave heating apparatus according to claim 18,

20. A waveguide for a microwave heating apparatus as in claim 17, wherein each of the delivery openings of the waveguide has a centerline, and the top side circumference and the bottom side circumference of each of the delivery openings are formed on both sides of the centerline;

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

a bottom body segment extending along the traveling wave path;

21. A waveguide tube for a microwave heating apparatus according to claim 17,

the top side peripheral edge of each of the delivery openings has:

a top body segment extending along the traveling wave path;

a bottom body section disposed opposite the top body section;

22. A waveguide tube for a microwave heating apparatus as claimed in claim 16, wherein the plate body thickness of opposite ends of each of the waveguide plates of the at least one waveguide plate pair is reduced.

23. A waveguide for a microwave heating apparatus as in claim 22, wherein a side of each waveguide plate connected to the waveguide has an abutting plane, the abutting plane extending along the traveling wave path; the other side of the wave guide plate is provided with:

24. A waveguide for a microwave heating apparatus as in claim 23 wherein each waveguide plate further has two second angled surfaces, each second angled surface being located between one of the first angled surfaces and the body surface; the inclination degree of the second inclined surface of each wave guide plate relative to the abutting plane is smaller than that of the first inclined surface relative to the abutting plane.

25. A waveguide for a microwave heating apparatus as in claim 22, wherein a side of each waveguide plate connected to the waveguide has an abutting plane, the abutting plane extending along the traveling wave path; the other side of the wave guide plate is provided with:

26. A waveguide for a microwave heating apparatus as in claim 22, wherein a side of each waveguide plate connected to the waveguide has an abutting plane, the abutting plane extending along the traveling wave path; the other side of the wave guide plate is provided with:

27. A waveguide for a microwave heating apparatus according to any of claims 17 to 26 wherein the direction of the microwave electric field between the two waveguides of the at least one pair of waveguides is parallel to the transport direction.