Microwave heating apparatus with high order mode suppression

Abstract

This invention discloses a microwave heating device with high-order mode suppression, belonging to the field of microwave heating technology. It includes: a heater comprising a rectangular waveguide and metal ridges; the rectangular waveguide has a microwave cavity extending laterally; two metal ridges are symmetrically arranged front-to-back within the microwave cavity, with a front-to-back spacing between them, and each ridge has a material passage hole extending front-to-back; and two high-order mode suppressors, respectively located at the front and rear ends of the heater, each high-order mode suppressor having a material cavity for the workpiece to be heated to pass through, extending front-to-back and communicating with the material passage hole. This invention features a compact structure, strong electric field, rapid and uniform heating, and protection against high-frequency radiation, preventing harm to operators from microwave spatial radiation and ensuring the safe use of the microwave heating device.

Description

Technical Field

[0001] This invention belongs to the field of microwave heating technology, and specifically relates to a microwave heating device with high-order mode suppression. Background Technology

[0002] Microwaves are electromagnetic waves with frequencies ranging from 300 MHz to 300 GHz. The heated medium contains polar molecules, whose polar orientation changes with the rapidly changing high-frequency electromagnetic field, causing molecular motion and friction. At this point, the field energy of the microwave field is converted into heat energy within the medium, raising the material's temperature and initiating a series of physicochemical processes, including thermochemical and puffing processes, thus achieving the purpose of microwave heating and drying.

[0003] Microwave heating has the following advantages: (1) Fast heating speed; microwave heating is completely different from traditional heating methods. It makes the material being heated itself a heat source, eliminating the need for heat conduction. Therefore, even materials with poor thermal conductivity can reach the heating temperature in a very short time. (2) Energy-saving and efficient; because substances containing moisture easily absorb microwaves and generate heat, there are almost no other losses except for a small amount of transmission loss, resulting in high thermal efficiency and energy saving. (3) Uniform heating; regardless of the shape of different parts of an object, microwave heating can make electromagnetic waves penetrate the object evenly from the surface to the interior to generate heat energy, resulting in good heating uniformity and preventing the phenomenon of the outside being burnt while the inside is still raw. (4) Anti-mildew, sterilization, and preservation. (5) Advanced technology and easy control. (6) Small footprint and safe and harmless. Therefore, microwave heating is widely used.

[0004] However, microwave heating often encounters severe limitations when the material loss is too high or too low. This is because: with high loss, to achieve uniform energy distribution along the width of the thin sheet, the power dissipation within the heating channel becomes excessive. Conversely, with low loss, increasing the number of heating channels is required to efficiently absorb useful power. Furthermore, prolonged exposure to electromagnetic radiation can negatively impact the health of workers. Therefore, existing microwave heating equipment requires further improvement. Summary of the Invention

[0005] The purpose of this invention is to provide a microwave heating device with high-order mode suppression, which has the advantages of miniaturized overall structure, high electric field strength, fast and uniform heating, and prevention of high-frequency radiation. It can be applied to thin sheet materials with too much or too little loss, and can avoid the health of operators from being affected by the spatial radiation of microwaves, thus ensuring safe use.

[0006] The technical solution adopted to solve the above-mentioned technical problems is as follows:

[0007] This invention discloses a microwave heating device with high-order mode suppression, comprising:

[0008] A heater includes a rectangular waveguide and metal ridges. The rectangular waveguide has a microwave cavity extending in the left and right directions. Two metal ridges are provided and symmetrically arranged in the microwave cavity. The two metal ridges have a front-to-back spacing and each has a material passage hole extending in the front-to-back direction.

[0009] Two high-order mold suppressors are provided and are respectively located at the front end and the rear end of the heater. Each high-order mold suppressor is provided with a material cavity for the workpiece to be heated to pass through. The material cavity extends along the front and rear and communicates with the material passage hole.

[0010] The present invention has at least the following beneficial effects: microwaves propagate in the left-right direction within the microwave cavity of the rectangular waveguide. When the sheet material enters the feed hole of the heater in the front-back direction, the microwave cavity of the rectangular waveguide has two symmetrical metal ridges, which improves the electric field distribution. A strong and uniform electric field is formed between the ridges of the two metal ridges, which increases the coupling between the sheet material and the low-loss sheet material. This allows the sheet material located between the two metal ridges to absorb microwave energy more quickly and uniformly, achieving rapid heating and uniform heating without increasing the heating channel and the power dissipation within the heating channel. Furthermore, high-order mode suppressors are set on both sides of the heater to limit the energy at the feed and discharge points of the heater, preventing high-frequency radiation leakage and protecting the human body from exposure to the electromagnetic environment, thus improving the safety of the microwave heating device.

[0011] As a further improvement to the above technical solution, the high-order mode suppressor includes a housing, a metal cylinder, and an electromagnetic wave absorber. The housing is connected to the rectangular waveguide. The housing is provided with the material cavity. The upper inner wall and the lower inner wall of the material cavity are provided with the metal cylinder and the electromagnetic wave absorber. The metal cylinder extends vertically and is located between the electromagnetic wave absorber and the heater.

[0012] With this configuration, when microwaves leak from the heater to the higher-order mode suppressor, the reactive metal cylinder causes a severe mismatch in the leaked microwave power, reflecting it back into the heater. Part of the reflected microwave power is absorbed by the sheet material, while the other part is dissipated on the inner wall of the heater, which helps to improve the utilization rate of microwave power. Then, the electromagnetic wave absorber absorbs the microwave power that is not reflected by the metal cylinder, minimizing microwave power leakage. Moreover, both the metal cylinder and the electromagnetic wave absorber are installed vertically inside the housing, which is effective in blocking higher-order modes of the TE mode and provides a wider impedance bandwidth.

[0013] As a further improvement to the above technical solution, the electromagnetic wave absorbing element is a silicon carbide block. By using a silicon carbide block with strong wave absorption capabilities, the thickness of the electromagnetic wave absorbing element can be designed to be smaller, absorbing as many electromagnetic waves as possible and preventing the human body from being affected by more electromagnetic waves.

[0014] As a further improvement to the above technical solution, the higher-order mode suppressor also includes a cooling component for cooling the electromagnetic wave absorber. This configuration allows the cooling component to cool the electromagnetic wave absorber, preventing overheating during operation and ensuring its effectiveness.

[0015] As a further improvement to the above technical solution, multiple metal cylinders are arranged at intervals along the left and right sides, and the multiple metal cylinders are grouped together. The housing is provided with multiple groups of metal cylinders arranged at intervals along the front and back sides. This arrangement, by providing multiple metal cylinders in both the front-back and left-right directions, enhances the microwave power reflection suppression effect of the higher-order mode suppressor, allowing microwave power to be reflected back to the heater as much as possible, thus preventing microwave power leakage.

[0016] As a further improvement to the above technical solution, multiple sets of the metal cylinders are arranged in an array or staggered. This arrangement increases the surface impedance of the high-order mode suppressor, enhances its suppression effect, and allows high-order modes to attenuate more quickly, thus preventing people from being affected by leaked microwave power.

[0017] As a further improvement to the above technical solution, the metal cylinder is a screw. This configuration allows for adjustment of the reactance of the higher-order mode suppressor by adjusting the screw's insertion depth.

[0018] As a further improvement to the above technical solution, the electromagnetic wave absorbing elements on the upper and lower sides are symmetrically arranged with respect to the material passage hole, and the metal cylinders on the upper and lower sides are also symmetrically arranged with respect to the material passage hole. This arrangement can better suppress microwave power leakage from the material passage hole, preventing harm to human health due to microwave power leakage.

[0019] As a further improvement to the above technical solution, from a top view, the metal ridge is high in the middle and low on both sides, and the material passage is located in the middle of the metal ridge. This arrangement increases the electric field strength at the material passage, makes the electric field more uniform, promotes its coupling with the low-loss sheet material, and allows the sheet material to heat up faster and be heated more evenly.

[0020] As a further improvement to the above technical solution, the front-to-back distance between the two metal ridges is set as 'a', and the vertical dimension of the material passage is set as 'b', where 'a' satisfies the following condition: 1.5b < a < 2b. This setting avoids the possibility of arcing and breakdown due to an excessively small gap between the two metal ridges, ensuring the safe operation of the microwave heating device. Furthermore, it prevents an excessively large gap between the two metal ridges from affecting electric field coupling, thereby improving the heating effect of the microwave heating device on sheet materials while ensuring safe operation. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0022] Figure 1 This is a three-dimensional structural view of the microwave heating device with high-order mode suppression provided in an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the internal structure of the microwave heating device with high-order mode suppression provided in an embodiment of the present invention;

[0024] Figure 3 This is a three-dimensional view of the microwave heating device with high-order mode suppression provided in the embodiment of the present invention when heating thin sheet materials;

[0025] Figure 4 yes Figure 3 A cross-sectional view of the microwave heating device with high-order mode suppression provided in the XZ plane;

[0026] Figure 5 This is a schematic diagram of the internal structure of the heater provided in an embodiment of the present invention;

[0027] Figure 6 yes Figure 3 A cross-sectional view of the microwave heating device with high-order mode suppression provided in the XY plane;

[0028] Figure 7 This is an electrical performance curve of the microwave heating device with high-order mode suppression provided in the embodiments of the present invention;

[0029] Figure 8 This is an electric field intensity distribution diagram of a microwave heating device with high-order mode suppression provided in an embodiment of the present invention;

[0030] Figure 9 This is a temperature distribution diagram of a sheet material under the simulation of a microwave heating device with high-order mode suppression provided in the embodiments of the present invention.

[0031] Figure 10This is a temperature rise curve of the sheet material under simulation using the microwave heating device with high-order mode suppression provided in the embodiments of the present invention.

[0032] The following labels are used in the attached diagram: 100, heater; 101, microwave cavity; 102, feed hole; 110, rectangular waveguide; 120, metal ridge; 200, high-order mode suppressor; 201, feed chamber; 210, housing; 220, silicon carbide block; 230, metal cylinder; 300, sheet material. Detailed Implementation

[0033] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0034] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0035] It should be noted that in the attached diagram, the X direction points from the rear to the front of the microwave heating device with high-order mode suppression, the Y direction points from the left to the right of the microwave heating device with high-order mode suppression, and the Z direction points from the lower to the upper side of the microwave heating device with high-order mode suppression.

[0036] In the description of this invention, the use of terms such as "a number" means one or more, with "more than" meaning two or more. Terms like "greater than," "less than," and "exceeding" are understood to exclude the stated number, while terms like "above," "below," and "within" are understood to include the stated number. The use of terms like "first," "second," and "third" is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, the number of indicated technical features, or the sequential relationship between indicated technical features.

[0037] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0038] Reference Figures 1 to 10 The following are several embodiments of the microwave heating device with high-order mode suppression of the present invention.

[0039] like Figures 1 to 10 As shown, Embodiment 1 of the present invention provides a microwave heating device with high-order mode suppression, capable of microwave heating thin sheet materials with high or low loss. The structure of the microwave heating device with high-order mode suppression includes a heater 100 and a high-order mode suppressor 200.

[0040] The heater 100 includes a rectangular waveguide 110 and a metal ridge 120.

[0041] The rectangular waveguide 110 has a microwave cavity 101 extending in the left-right direction, thus allowing microwaves within the cavity to propagate in the left-right direction. The microwave cavity 101 penetrates both the left and right sides of the rectangular waveguide 110, meaning the rectangular waveguide 110 has a left-side opening and a right-side opening. In this embodiment, the right-side opening of the rectangular waveguide 110 is the microwave inlet, and the left-side opening is the microwave outlet. The long side of the rectangular waveguide 110 extends in the vertical direction, and the wide side extends in the front-back direction. It can be understood that a regular metal waveguide made of a metallic material (copper, aluminum, etc.), with a rectangular cross-section and filled with air, is called a rectangular waveguide 110.

[0042] Two metal ridges 120 are disposed within the microwave cavity 101 and arranged symmetrically front to back. Specifically, one metal ridge 120 is connected to the inner front wall of the microwave cavity 101, and the other metal ridge 120 is connected to the inner rear wall of the microwave cavity 101. The metal ridges 120 and the rectangular waveguide 110 can be connected by welding or integral molding. The metal ridges 120 and the rectangular waveguide 110 can be made of 6061 aluminum alloy.

[0043] There is a certain front-to-back distance between the two metal ridges 120, that is, the two metal ridges 120 do not contact each other. Moreover, each metal ridge 120 is provided with a feed hole 102, which extends along the front-to-back direction and communicates with the microwave cavity 101. Furthermore, the central axes of the feed holes 102 of the two metal ridges 120 coincide, one feed hole 102 penetrates the front side of the rectangular waveguide 110, and the other feed hole 102 penetrates the rear side of the rectangular waveguide 110.

[0044] From a frontal view, the feed hole 102 can be located in the middle of the metal ridge 120, and the feed hole 102 is square. The feed hole 102 allows the sheet material 300 to pass through. From a top view, the metal ridge 120 is high in the middle and low on both sides. In some embodiments, the shape of the metal ridge 120 is an isosceles trapezoid from a top view. In other embodiments, the metal ridge 120 is T-shaped. From a top view, the feed hole 102 is located in the middle of the metal ridge 120, which increases the electric field strength at the feed hole 102, makes the electric field more uniform, promotes its coupling with the low-loss sheet material 300, and makes the sheet material 300 heat up faster and heat more evenly. In this embodiment, the central axis of the feed hole 102 coincides with the central axis of the metal ridge 120.

[0045] In some embodiments, such as Figure 4 and Figure 5 As shown, the front-to-back distance between the two metal ridges 120 is set as 'a', and the vertical dimension of the material passage 102 is set as 'b', where 'a' satisfies the following condition: 1.5b < a < 2b. This arrangement between the metal ridges 120 and the material passage 102 avoids the problem of arcing and breakdown due to an excessively small gap between the two metal ridges 120, which could affect the safety of the microwave heating device. Furthermore, it prevents the electric field coupling from being affected by an excessively large gap between the two metal ridges 120, thus ensuring high safety performance of the microwave heating device and improving its heating effect on the sheet material 300.

[0046] There are two higher-order mode suppressors 200, which are spaced apart in the front-to-back direction. One higher-order mode suppressor 200 is located at the front end of the heater 100, and the other higher-order mode suppressor 200 is located at the rear end of the heater 100. In this embodiment, the two higher-order mode suppressors 200 are symmetrical about the heater 100. The higher-order mode suppressors 200 and the heater 100 can be connected and fixed by welding.

[0047] Each higher-order mode suppressor 200 is provided with a feed cavity 201, which extends in the front-to-back direction and passes through the front and rear sides of the higher-order mode suppressor 200 respectively. The feed cavity 201 is used for the passage of the part to be heated, such as a sheet material 300, which moves relative to the microwave heating device in the front-to-back direction. After the higher-order mode suppressor 200 is connected to the rectangular waveguide 110, the feed cavity 201 is connected to the feed hole 102.

[0048] In this embodiment, the high-order mode suppressor 200 located in front of the heater 100 is the inlet high-order mode suppressor 200, and the high-order mode suppressor 200 located behind the heater 100 is the outlet high-order mode suppressor 200. The area between the two metal ridges 120 is the heating zone, which transmits microwave power. Therefore, the sheet material 300 passes through the inlet high-order mode suppressor 200, the heater 100, and the outlet high-order mode suppressor 200 sequentially from front to back. When it stays in the heating zone, it absorbs enough heat and exits the heating zone when the temperature of the sheet material 300 reaches a predetermined value, thereby achieving the heating and temperature rise treatment of the sheet material 300 in the heater 100.

[0049] Understandably, when using this microwave heating device to microwave heat the sheet material 300, as the sheet material 300 moves along the front-to-back direction and moves to the position between the two metal ridges 120 inside the heater 100, the two symmetrical metal ridges 120 inside the rectangular waveguide 110 can improve the electric field distribution, causing a strong and uniform electric field to be formed between the ridges of the two metal ridges 120. This can increase the coupling between the ridges and the low-loss sheet material 300, allowing the sheet material 300 located between the two metal ridges 120 to absorb microwave energy faster and more uniformly. This achieves the goal of rapid heating and uniform heating of the sheet material 300. Compared with the prior art, there is no need to increase the heating channel and the power dissipation within the heating channel. Moreover, the overall structure has fewer parts and is simple to process, enabling the microwave heating device to be miniaturized.

[0050] Since the damage caused by radio frequency and microwaves is mainly divided into thermal and non-thermal effects, human tissues are highly susceptible to microwave radiation. Therefore, it is essential to protect the human body from exposure to the electromagnetic environment. To address this issue, high-order mode suppressors 200 are installed at both ends of the heater 100 to limit the energy at the feed and discharge points of the heater 100, preventing high-frequency radiation leakage. This avoids health risks to workers due to exposure to the electromagnetic environment and improves the safety performance of the microwave heating device.

[0051] In some embodiments, such as Figures 1 to 4 and Figure 6 As shown, the structure of the high-order mode suppressor 200 includes a housing 210, a metal cylinder 230, and an electromagnetic wave absorbing element.

[0052] In this embodiment, viewed from the front, the housing 210 is square, and can be a rectangular waveguide 110 structure. The long side of the housing 210 extends in the left-right direction, and the wide side extends in the up-down direction. The housing 210 is provided with a through-cavity 201 extending from front to back, and the housing 210 is connected and fixed to the rectangular waveguide 110. The housing 210 can be made of 6061 aluminum alloy. A metal cylinder 230 and an electromagnetic wave absorber are disposed within the through-cavity 201 of the housing 210. Viewed from the front, the metal cylinder 230 and the electromagnetic wave absorber are located on the wide side of the housing 210.

[0053] Specifically, two sets of metal cylinders 230 are provided, arranged vertically and alternately, thus creating a vertical gap between the two sets of metal cylinders 230 to allow the sheet material 300 to pass through. One set of metal cylinders 230 is connected to the inner upper wall of the material cavity 201, and the other set of metal cylinders 230 is connected to the inner lower wall of the material cavity 201. It can be understood that each set of metal cylinders 230 includes multiple metal cylinders 230, with both ends of the metal cylinders 230 extending vertically.

[0054] In this embodiment, each group of metal cylinders 230 includes multiple metal cylinders 230 spaced apart in the left-right direction. Furthermore, multiple groups of metal cylinders 230 are arranged at certain intervals along the front-back direction of the housing 210, and these multiple groups of metal cylinders 230 are arranged in an array. It is understood that arranging multiple metal cylinders 230 in the front-back and left-right directions of the material cavity 201 can increase the surface impedance of the higher-order mode suppressor 200, thereby enhancing the reflection and suppression effect of the higher-order mode suppressor 200 on microwave power. This allows the microwave power to be reflected into the heater 100 as much as possible, resulting in faster attenuation of higher-order modes and preventing microwave power leakage.

[0055] In other embodiments, the multiple sets of metal cylinders 230 are arranged in a staggered manner.

[0056] The metal cylinder 230 can be a pin or a screw. In this embodiment, a screw is used, and the housing 210 is provided with a screw hole, which the screw can connect to. Therefore, by adjusting the insertion depth of the screw, the reactance of the higher-order mode suppressor 200 can be adjusted, allowing the susceptance to change continuously from capacitive to inductive.

[0057] In other embodiments, baffles or diaphragms may be used instead of the metal cylinder 230. However, the metal cylinder 230 produces better surface impedance.

[0058] Two sets of electromagnetic wave absorbers are provided, arranged vertically and alternately, with a certain vertical distance between the two sets. One set of electromagnetic wave absorbers is connected and fixed to the upper inner wall of the material cavity 201, and the other set is connected and fixed to the lower inner wall of the material cavity 201. The electromagnetic wave absorbers are located at the end of the housing 210 away from the material passage 102, and the metal cylinder 230 is located between the electromagnetic wave absorbers and the heater 100. It is understood that each set of electromagnetic wave absorbers may include one, two, or more electromagnetic wave absorbers.

[0059] In some embodiments, the electromagnetic wave absorbing element is made of a wave-absorbing material such as graphite or ferrite. In this embodiment, the electromagnetic wave absorbing element is a silicon carbide block 220, which is fixed inside the housing 210 by a silicone rubber adhesive.

[0060] Understandably, microwaves within heater 100 inevitably leak to the higher-order mode suppressor 200 during transmission. In this case, the metal cylinder 230 within housing 210, due to its reactive properties, can cause a severe mismatch in the leaked microwave power, reflecting it back into heater 100. A portion of the reflected microwave power is effectively absorbed by the sheet material 300, while the remaining portion is dissipated on the inner wall of heater 100, preventing microwave power leakage and improving microwave power utilization. Furthermore, electromagnetic wave absorbers can be used to absorb the microwave power not reflected by the metal cylinder 230 (i.e., the remaining microwave power), minimizing microwave power leakage.

[0061] Moreover, both the metal cylinder 230 and the electromagnetic wave absorbing component are installed vertically within the housing 210, which provides good performance for blocking higher-order modes of the TE mode and results in a wider impedance bandwidth.

[0062] To prevent the silicon carbide block 220 from overheating during operation, the high-order mode suppressor 200 also includes a cooling assembly. The cooling assembly cools the electromagnetic wave absorber. In this embodiment, the cooling assembly may include a cooling water pipe, using water to absorb the heat generated by the silicon carbide block 220, thereby preventing the electromagnetic wave absorber from overheating and affecting its performance. The cooling water pipe may be coiled inside the silicon carbide block 220 or located on one side of the silicon carbide block 220.

[0063] In other embodiments, the cooling assembly uses air cooling to cool the silicon carbide block 220.

[0064] In this embodiment, the electromagnetic wave absorbing elements on the upper and lower sides are symmetrically arranged about the material passage hole 102, and the metal cylinders 230 on the upper and lower sides are symmetrically arranged about the material passage hole 102. This can better suppress the microwave power leaking from the material passage hole 102, prevent microwave power leakage from threatening human health, and thus ensure the safety of the staff.

[0065] The microwave heating device in this embodiment adopts the following structural configuration: two symmetrical metal ridges 120 are provided in the rectangular waveguide 110. The metal ridges 120 are high in the middle and low on both sides. The relationship between the front-to-back distance a of the two metal ridges 120 and the vertical dimension b of the feed hole 102 is 1.5b < a < 2b. Furthermore, high-order mode suppressors 200 are symmetrically arranged at both ends of the rectangular waveguide 110. The high-order mode suppressors 200 are composed of silicon carbide blocks 220 and screws. The silicon carbide blocks 220 and screws are symmetrically arranged vertically about the feed hole 102.

[0066] like Figure 7 As shown, the microwave heating device using the above structure was simulated in the microwave frequency range of 2.3 GHz to 2.6 GHz. The results showed that the minimum value of the input reflection coefficient S11 (also known as the input return loss) was -50.79636 dB, and the value of the forward transmission coefficient S21 (also known as the insertion loss) was -0.61069179 dB.

[0067] Understandably, a smaller value for S11 is better, generally recommended to be S11 < 0.1, i.e., -20dB; a larger value for S21 is better, ideally 1, i.e., 0dB. A larger S21 results in higher transmission efficiency, generally recommended to be S21 > 0.7, i.e., -3dB. Specifically, when the microwave frequency is around 2.45GHz, S11 is less than -50dB, and S21 reaches -0.6dB, resulting in low input return loss and good transmission performance of the microwave heating device, enabling rapid and uniform heating of the sheet material 300.

[0068] like Figure 8 As shown, when the heater 100 uses microwave transmission with a microwave power of 2.45 GHz, the electric field strength is large and the electric field strength distribution is uniform at the middle position of the two metal ridges 120. Figure 9 and Figure 10 As shown, the sheet material 300 located between the two metal ridges 120 is heated uniformly and the temperature rises rapidly. Therefore, this microwave heating device can be applied to sheet materials 300 with too much or too little loss.

[0069] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A microwave heating device with high-order mode suppression, characterized in that, include: A heater includes a rectangular waveguide and metal ridges. The rectangular waveguide has a microwave cavity extending left and right, penetrating the left and right sides of the waveguide to allow microwaves to propagate in the left-right direction. Two metal ridges are symmetrically arranged in the microwave cavity, with a front-to-back distance between them, and each ridge has a material passage extending front-to-back. One metal ridge is connected to the inner front wall of the microwave cavity, and the other is connected to the inner rear wall. The material passage communicates with the microwave cavity. Viewed from above, the metal ridges are higher in the middle and lower on both sides, with the material passage located in the middle of the ridges. The central axis of the material passage coincides with the central axis of the metal ridges. The material passage allows sheet material to pass through. Two high-order mold suppressors are provided and are respectively located at the front end and the rear end of the heater. Each high-order mold suppressor is provided with a material cavity for the workpiece to be heated to pass through. The material cavity extends along the front and rear and communicates with the material passage hole.

2. The microwave heating device with high-order mode suppression according to claim 1, characterized in that, The higher-order mode suppressor includes a housing, a metal cylinder, and an electromagnetic wave absorber. The housing is connected to the rectangular waveguide. The housing is provided with a material cavity. The upper inner wall and the lower inner wall of the material cavity are provided with the metal cylinder and the electromagnetic wave absorber. The metal cylinder extends vertically and is located between the electromagnetic wave absorber and the heater.

3. The microwave heating device with high-order mode suppression according to claim 2, characterized in that, The electromagnetic wave absorbing element is a silicon carbide block.

4. The microwave heating device with high-order mode suppression according to claim 3, characterized in that, The higher-order mode suppressor also includes a cooling assembly for cooling the electromagnetic wave absorber.

5. The microwave heating device with high-order mode suppression according to claim 2, characterized in that, The metal cylinders are provided in multiple groups and arranged at intervals along the left and right sides. The multiple metal cylinders are arranged as a group, and the shell is provided with multiple groups of metal cylinders arranged at intervals along the front and back sides.

6. The microwave heating device with high-order mode suppression according to claim 5, characterized in that, The multiple sets of the metal cylinders are arranged in an array or staggered.

7. The microwave heating device with high-order mode suppression according to claim 6, characterized in that, The metal cylinder is a screw.

8. The microwave heating apparatus with high-order mode suppression according to any one of claims 2 to 7, characterized in that, The electromagnetic wave absorbing elements on the upper and lower sides are symmetrically arranged with respect to the material passage hole, and the metal cylinders on the upper and lower sides are symmetrically arranged with respect to the material passage hole.

9. The microwave heating device with high-order mode suppression according to claim 1, characterized in that, The front-to-back distance between the two metal ridges is set as a, and the vertical dimension of the feed hole is set as b. a satisfies the following condition: 1.5b < a < 2b.

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