Microwave heating cavity

Abstract

A microwave heating cavity, comprising a metal housing (1). A through middle chamber is formed in the metal housing, and a first mounting chamber (110), an inwardly recessed air cavity (120), and a second mounting chamber (130) are sequentially formed in the middle chamber in the length direction of the middle chamber; a heating sleeve body (2) is mounted in the first mounting chamber, an accommodating cavity (210) is provided inside the heating sleeve body, a dielectric medium (3) is provided in the accommodating cavity, the upper end of the dielectric medium extends to the outside of the heating sleeve body, and the lower end of the heating sleeve body extends into the inwardly recessed air cavity; an antenna support (4) is mounted in the second mounting chamber, a ceramic rod (5) is mounted in the middle of the antenna support, the ceramic rod extends to the accommodating cavity and is in contact with the dielectric medium, and a metal lead (6) externally connected to a power supply is helically wound around the periphery of the ceramic rod.

Description

A microwave heating cavity

[0001] This patent application claims priority to Chinese patent application No. CN 202410197908.X filed on February 22, 2024. The disclosure of the prior application is incorporated herein by reference in its entirety. Technical Field

[0002] The present application belongs to the field of microwave heating technology, and more specifically, relates to a microwave heating cavity. Background Art

[0003] Existing microwave heating technologies commonly utilize frequency bands such as the L band (890MHz-940MHz) and the S band (2400MHz-2500MHz). Microwave heating technology is widely used in food processing, material drying, ceramic sintering, metal smelting, biocidal lamps, and microwave medical treatment. For example, CN109764368A discloses microwave ovens. Miniaturized, portable heating devices primarily utilize resistance wire heating or electromagnetic eddy current heating, as described in CN116763017A.

[0004] Technologies such as microwave ovens utilize multi-feed inputs. Their advantages include volumetric heating, energy conservation, environmental protection, and strong penetration. However, their disadvantages are that microwave heating is theoretically affected by the wavelength of the microwaves, making miniaturization difficult and unfavorable for portable devices. Resistance wire heating or electromagnetic eddy current heating methods utilize surface contact heating, but lack the advantages of microwave heating and lack effective carbonization of the dielectric medium. Furthermore, resistance wire heating requires the addition of a heating plate or rod to the heating chamber (compared to microwave heating). These plates or rods pierce the dielectric medium during heating, which can easily result in residual dielectric material after heating, hindering cleaning of the heating chamber. While electromagnetic eddy current heating eliminates the need for additional heating plates or rods, making it easier to clean the heating chamber, it does require the addition of additional materials such as metal sheets to the dielectric medium. Technical issues

[0005] The purpose of this application is to provide a microwave heating cavity to achieve miniaturization of the equipment, increase energy input utilization, and realize electromagnetic field volume heating within an effective range; the heating method of the microwave heating cavity provided in this application is between surface contact heating and volume heating, and a balance is achieved between the two. Technical Solutions

[0006] To achieve the above-mentioned object, the technical solution adopted in the present application is as follows: providing a microwave heating cavity, comprising a metal shell, wherein a through-intermediate cavity is provided inside the metal shell, wherein the intermediate cavity is sequentially formed along its length into a first mounting cavity, a concave air cavity, and a second mounting cavity;

[0007] A heating sleeve is installed in the first installation chamber, wherein a receiving cavity is provided inside the heating sleeve, wherein a dielectric medium is provided in the receiving cavity, wherein the upper end of the dielectric medium extends to the outside of the heating sleeve, and the lower end of the heating sleeve extends into the concave air cavity;

[0008] An antenna bracket is installed in the second installation cavity, a ceramic rod is installed in the middle of the antenna bracket, the ceramic rod extends to the accommodating cavity and contacts the dielectric medium, and a metal lead of an external power supply is spirally wound around the outer circumference of the ceramic rod.

[0009] In a possible implementation, the metal shell is made of a material with a high electrical conductivity, and an outer wall of the metal shell is provided with an oxide layer.

[0010] In a possible implementation, the heating sleeve is made of a microwave-transmissive material.

[0011] In one possible implementation, an end plate is provided at the lower end of the heating sleeve, a through hole is provided in the middle of the end plate for the ceramic rod to pass through, a flange is circumferentially provided at the upper end of the heating sleeve, an annular limit groove is provided at the upper end of the first installation chamber, and the flange is provided in the annular limit groove to limit the depth of the heating sleeve inserted into the concave air cavity.

[0012] In a possible implementation, a recess is provided in the middle of the lower end of the dielectric medium, and the recess is arranged corresponding to the through hole to wrap around the upper end of the ceramic rod.

[0013] In a possible implementation, the length of the lower end of the heating sleeve penetrating into the concave air cavity is greater than half the length of the concave air cavity.

[0014] In a possible implementation, the ceramic rod is made of aluminum oxide or zirconium oxide. A spiral groove is formed on an outer wall of the ceramic rod, and the metal lead is wound in the spiral groove.

[0015] In a possible implementation, an outer wall of the ceramic rod is provided with an insulating layer, and the insulating layer is wrapped around the outside of the metal lead.

[0016] In one possible implementation, the concave air cavity includes an upper conical chamber and a lower conical chamber, the diameter of the upper conical chamber increases from top to bottom, the diameter of the lower conical chamber increases from bottom to top, and the lower end of the heating sleeve extends into the lower conical chamber.

[0017] In a possible implementation, an angle between the upper conical chamber and the central axis of the heating jacket is 20° to 45°. Beneficial effects

[0018] The microwave heating chamber provided in this application has the following advantages: compared to the prior art, a dielectric medium is inserted from top to bottom into the accommodating cavity of a heating sleeve. The heating sleeve, along with the dielectric medium, is then inserted from top to bottom into the intermediate chamber of a metal shell. The heating sleeve is installed in a first mounting chamber, with the lower end of the heating sleeve inserted into the concave air cavity. A metal lead is spirally wound around a ceramic rod, which is vertically mounted on an antenna bracket and installed as a whole within a second mounting chamber. The ceramic rod extends into the concave air cavity, with the upper end of the ceramic rod resting against the lower end of the dielectric medium to ensure full contact between the two. The metal lead is then connected to a power source. The metal lead spirally wound around the ceramic rod generates an electromagnetic field within the concave air cavity, which electromagnetically heats the dielectric medium. Simultaneously, a portion of the microwave energy carried by the electromagnetic field is directly converted into heat energy to heat the ceramic rod. The ceramic rod also heats the dielectric medium through heat conduction, resulting in a dual heating of the dielectric medium, allowing it to quickly reach the desired temperature. The microwave heating cavity provided in the present application realizes the miniaturization of the equipment, increases the energy input utilization rate, and can realize electromagnetic field volume heating within the effective range; the heating method of the microwave heating cavity provided in the present application is between surface contact heating and volume heating, and strikes a balance between the two. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] FIG1 is a schematic structural diagram of a microwave heating cavity provided in the present application;

[0021] FIG2 is a schematic structural diagram of a metal shell of a microwave heating cavity provided in the present application;

[0022] FIG3 is a schematic structural diagram of a heating jacket of a microwave heating cavity provided in the present application;

[0023] FIG4 is a schematic diagram of the structure of the dielectric medium of the microwave heating cavity provided by the present application;

[0024] FIG5 is a schematic structural diagram of an antenna support, a ceramic rod, and a metal lead of a microwave heating cavity provided in the present application;

[0025] FIG6 is a schematic structural diagram of a microwave heating cavity provided in another embodiment of the present application;

[0026] FIG7 is a partial enlarged view of point A in FIG6 .

[0027] Description of reference numerals:

[0028] 1. Metal shell; 110. First installation chamber; 120. Concave air chamber; 121. Upper conical chamber; 122. Lower conical chamber; 130. Second installation chamber; 140. Annular limit groove; 150. Oxide layer; 160. Heating layer; 2. Heating sleeve; 210. Accommodating chamber; 220. End plate; 230. Flange; 240. Through hole; 3. Dielectric medium; 310. Recess; 4. Antenna bracket; 5. Ceramic rod; 6. Metal lead. Modes for Carrying Out the Invention

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the following further describes this application in detail with reference to the accompanying drawings and implementation methods. It should be understood that the specific implementation methods described herein are only used to explain this application and are not intended to limit this application.

[0030] Please refer to Figures 1 to 5. In one embodiment, the microwave heating cavity provided in the present application includes a metal shell 1, and a through intermediate cavity is provided inside the metal shell 1. The intermediate cavity forms a first installation cavity 110, a concave air cavity 120 and a second installation cavity 130 in sequence along its length direction; a heating sleeve 2 is installed in the first installation cavity 110, and a accommodating cavity 210 is provided inside the heating sleeve 2. A dielectric medium 3 is provided in the accommodating cavity 210, and the upper end of the dielectric medium 3 extends to the outside of the heating sleeve 2, and the lower end of the heating sleeve 2 extends into the concave air cavity 120; an antenna bracket 4 is installed in the second installation cavity 130, and a ceramic rod 5 is installed in the middle of the antenna bracket 4. The ceramic rod 5 extends to the accommodating cavity 210 and contacts the dielectric medium 3. A metal lead 6 for an external power supply is spirally wound around the outer circumference of the ceramic rod 5.

[0031] In this embodiment, the microwave heating cavity provided by the present application has the following beneficial effects compared to the prior art. The dielectric medium 3 is inserted from top to bottom into the accommodating cavity 210 of the heating sleeve 2. The heating sleeve 2 and the dielectric medium 3 are inserted from top to bottom into the middle cavity of the metal shell 1. The heating sleeve 2 is installed in the first installation cavity 110. At this time, the lower end of the heating sleeve 2 is inserted into the concave air cavity 120. The metal lead 6 is spirally wound around the ceramic rod 5. The ceramic rod 5 is vertically mounted on the antenna bracket 4 and the entire assembly is installed in the second installation cavity 130. The ceramic rod 5 extends into the concave air cavity 120. At the same time, the upper end of the ceramic rod 5 abuts against the lower end of the dielectric medium 3 to ensure full contact between the two. The metal lead 6 is powered on. The metal lead 6 spirally wound around the ceramic rod 5 will form an electromagnetic field in the concave air cavity 120, forming electromagnetic field heating on the dielectric medium 3. At the same time, a portion of the microwave energy carried by the electromagnetic field is directly converted into heat energy to heat the ceramic rod 5. The ceramic rod 5 also heats the dielectric medium 3 by heat conduction. The dielectric medium 3 is heated doubly, thereby quickly reaching the desired temperature. The microwave heating cavity provided by this application achieves equipment miniaturization, increases energy input utilization, and can achieve electromagnetic field volume heating within an effective range. The heating method of the microwave heating cavity provided by this application is between surface contact heating and volumetric heating, and strikes a balance between the two.

[0032] The dielectric medium 3 is a heating object and can be a material such as incense, tobacco, etc. Its characteristic is that the microwave attenuation coefficient is large, and it can absorb microwave energy, generate polarized molecules, and convert them into heat energy.

[0033] Optionally, the metal shell 1 can be made of a high-conductivity material, such as aluminum, copper, or other metal materials with high conductivity. The metal shell 1 is used to reflect and shield microwaves, following the skin effect. The metal shell 1 will not theoretically cause microwave energy attenuation, and will cause negligible microwave energy attenuation in engineering. Microwave energy can be effectively converted into heat energy after multiple reflections by the metal shell 1 and absorbed by the dielectric medium 3. At the same time, the metal shell 1 can prevent microwave leakage, generate harmful radiation, and cause damage to the human body. Optionally, the outer wall of the metal shell 1 can be provided with an oxide layer 150. The oxide layer 150 can serve as a microwave boundary. The oxide layer 150 can be obtained by directly oxidizing the outer wall of the metal shell 1.

[0034] Optionally, the heating jacket 2 can be made of a microwave-transparent material, such as plastic or ceramic. The heating jacket 2 is designed with an independent cavity (accommodation cavity 210) that serves as the heating chamber for the dielectric medium 3. This independent cavity facilitates cleaning even if residual dielectric material remains on its inner walls. Furthermore, the dielectric medium 3 is heated using a hybrid heating method: thermal conduction heating by the ceramic rod 5 and microwave heating within the concave air cavity 120. This hybrid heating method rapidly heats the dielectric medium 3 to the desired temperature, with microwave heating facilitating uniform heating.

[0035] The lower end of the heating jacket 2 is provided with an end plate 220, and a through hole 240 is provided in the middle of the end plate 220 for the passage of the ceramic rod 5. The upper end of the heating jacket 2 is provided with a flange 230 circumferentially. The upper end of the first mounting chamber 110 is provided with an annular limiting groove 140. The flange 230 is arranged in the annular limiting groove 140 to limit the depth of the heating jacket 2 inserted into the concave air cavity 120.

[0036] A recess 310 is provided in the middle of the lower end of the dielectric medium 3. The recess 310 is arranged corresponding to the through hole 240 to wrap around the upper end of the ceramic rod 5, so that the ceramic rod 5 can more fully contact the dielectric medium 3 and improve the heat conduction efficiency of the dielectric medium 3.

[0037] The length of the lower end of the heating sleeve 2 penetrating into the concave air cavity 120 is greater than half the length of the concave air cavity 120, so that more of the dielectric medium 3 is located in the concave air cavity 120, thereby obtaining sufficient microwave heating and improving the efficiency of microwave heating of the dielectric medium 3.

[0038] Ceramic rod 5 is made of aluminum oxide or zirconium oxide, which offers excellent insulation, a highly stable molecular structure, no polarization under microwaves, and minimal microwave attenuation. Ceramic rod 5 is used to attach metal lead 6, forming a microwave heating cavity. The outer wall of ceramic rod 5 can be provided with a spiral groove, around which metal lead 6 is wound, ensuring the stability of metal lead 6.

[0039] The metal lead 6 can be made of a nickel alloy with low resistivity. The metal wire diameter of the metal lead 6 can be φ0.2 mm, and the metal wire is wound according to a certain length to form a microwave heating cavity antenna suitable for the S segment (2400MHz-2500MHz).

[0040] Optionally, an insulating layer can be provided on the outer wall of the ceramic rod 5, and the insulating layer can be wrapped around the outside of the metal lead 6. The insulating layer can be formed by high-temperature glass glaze, which is applied to the outer wall of the ceramic rod 5 after the metal lead 6 is wrapped. This can protect the stability of the metal lead 6 and optimize the surface smoothness of the ceramic rod 5, achieving a bandwidth of 160MHz to 180MHz.

[0041] Optionally, the concave air cavity 120 includes an upper conical chamber 121 and a lower conical chamber 122. The diameter of the upper conical chamber 121 increases from top to bottom, while the diameter of the lower conical chamber 122 increases from bottom to top. The lower end of the heating jacket 2 extends into the lower conical chamber 122. The metal lead 6 spirally wound around the ceramic rod 5 generates an alternating electromagnetic field at the end of the ceramic rod 5. This alternating electromagnetic field formed at the upper end of the ceramic rod 5 penetrates the heating jacket 2, heating the dielectric medium 3 with microwaves. The concave air cavity 120 facilitates the upward propagation of microwaves emitted from the metal lead 6 to the dielectric medium 3, thereby improving the efficiency of microwave heating. Specifically, the angle between the upper conical chamber 121 and the central axis of the heating jacket 2 can be 20° to 45°. In this case, microwaves are transmitted in the concave air cavity 120, pass through the dielectric medium 3, and are converted into heat.

[0042] In another embodiment, referring to Figures 6 and 7 , the concave air cavity 120 can be a spherical cavity, with the lower end of the heating jacket 2 positioned below the center of the spherical cavity. The inner wall of the spherical cavity is formed with multiple tapered cavities spaced evenly from top to bottom. The inner diameter of each tapered cavity gradually decreases from top to bottom, thereby forming an inclined conical surface around the circumference of the conical cavity. A heating layer 160 coated with high-purity iron powder, gravel particles, and a catalyst can be adhered to the inclined conical surface. The catalyst can be a mixture of activated carbon and an inorganic salt. The magnetic flux lines formed at the upper end of the ceramic rod 5 penetrate the heating sleeve 2 and act on the heating layer 160. By changing the current on the metal lead 6, the trajectory of the magnetic flux lines can be changed, so that the high-purity iron powder in the heating layer 160 is displaced under the action of the magnetic flux lines, and the high-purity iron powder rubs against the gravel particles; at the same time, under the action of the catalyst, the high-purity iron powder is oxidized with the air in the concave air cavity 120, generating heat to further heat the dielectric medium 3 in the above-mentioned heating sleeve 2, forming a triple heating method with the combination of contact heating and electromagnetic field heating.

[0043] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A microwave heating cavity, characterized in that: The invention comprises a metal shell (1), wherein a through-intermediate chamber is provided inside the metal shell (1), and the intermediate chamber sequentially forms a first installation chamber (110), an inwardly concave air chamber (120), and a second installation chamber (130) along its length direction; A heating sleeve (2) is installed in the first installation chamber (110), a receiving chamber (210) is provided inside the heating sleeve (2), a dielectric medium (3) is provided in the receiving chamber (210), an upper end of the dielectric medium (3) extends to the outside of the heating sleeve (2), and a lower end of the heating sleeve (2) extends into the concave air cavity (120); An antenna bracket (4) is installed in the second installation chamber (130), a ceramic rod (5) is installed in the middle of the antenna bracket (4), the ceramic rod (5) extends to the accommodating chamber (210) and contacts the dielectric medium (3), and a metal lead (6) for an external power supply is spirally wound around the outer periphery of the ceramic rod (5).

2. A microwave heating cavity according to claim 1, characterized in that: The metal shell (1) is made of a high-conductivity material, and an outer wall of the metal shell (1) is provided with an oxide layer (150).

3. A microwave heating cavity according to claim 1, characterized in that: The heating sleeve (2) is made of a microwave-transmissive material.

4. A microwave heating cavity according to claim 3, characterized in that: The lower end of the heating sleeve (2) is provided with an end plate (220), the middle part of the end plate (220) is provided with a through hole (240) for the ceramic rod (5) to pass through, the upper end of the heating sleeve (2) is provided with a flange (230) in the circumferential direction, the upper end of the first installation chamber (110) is provided with an annular limiting groove (140), and the flange (230) is provided in the annular limiting groove (140) to limit the depth of the heating sleeve (2) inserted into the concave air cavity (120).

5. A microwave heating cavity according to claim 4, characterized in that: A recess (310) is provided in the middle of the lower end of the dielectric medium (3), and the recess (310) is arranged corresponding to the through hole (240) to wrap around the upper end of the ceramic rod (5).

6. A microwave heating cavity according to claim 4, characterized in that: The length of the lower end of the heating sleeve (2) penetrating into the concave air cavity (120) is greater than half the length of the concave air cavity (120).

7. The microwave heating cavity according to claim 1, characterized in that: The ceramic rod (5) is made of aluminum oxide or zirconium oxide. A spiral groove is provided on the outer wall of the ceramic rod (5), and the metal lead (6) is wound in the spiral groove.

8. A microwave heating cavity according to claim 7, characterized in that: The outer wall of the ceramic rod (5) is provided with an insulating layer, and the insulating layer is wrapped around the outside of the metal lead (6).

9. The microwave heating cavity according to claim 1, characterized in that: The concave air cavity (120) comprises an upper conical chamber (121) and a lower conical chamber (122), the diameter of the upper conical chamber (121) increases from top to bottom, the diameter of the lower conical chamber (122) increases from bottom to top, and the lower end of the heating jacket (2) extends into the lower conical chamber (122).

10. The microwave heating cavity according to claim 9, characterized in that: The angle between the upper conical chamber (121) and the central axis of the heating jacket (2) is 20° to 45°.

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