Electromagnetic wave feed-in device
By introducing a coupling structure and a heating element into the microwave oven, the reflected electromagnetic waves are monitored and converted into heat, thus solving the problem of poor electromagnetic wave source matching, protecting the equipment and improving energy efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WUXI CARBON TECH CO LTD
- Filing Date
- 2025-05-21
- Publication Date
- 2026-04-24
AI Technical Summary
Existing microwave ovens are prone to damage due to poor matching of electromagnetic wave sources when processing different materials, and the equipment has low energy efficiency. Directional couplers increase cost and complexity.
An electromagnetic wave feeding device is used, which includes a coupling structure and a heating element. The reflected electromagnetic wave energy is converted into heat through the coupling structure, and the matching status is monitored and the electromagnetic wave source is protected by a temperature detector and a temperature control switch.
It achieves protection of electromagnetic wave sources and improves energy efficiency, simplifies equipment structure, reduces costs, and improves the matching of energy transmission.
Smart Images
Figure CN224164912U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of electromagnetic waves, and in particular to an electromagnetic wave feeding device. Background Technology
[0002] Household microwave ovens and tunnel-type industrial microwave ovens are widely used in homes and industrial and agricultural production. Microwaves can process materials located in the processing chamber, including but not limited to heating, defrosting, drying, sterilizing, and sintering.
[0003] A typical microwave oven consists of an electromagnetic wave source, a processing cavity, a feed port, and the material being processed. During microwave oven operation, when heating or deep drying the material, the electromagnetic wave source is often in a mismatched state due to differences in the quantity, density, humidity, and shape of the material in the processing cavity. This reduces the energy efficiency of the equipment and can easily lead to the burnout or shortened lifespan of the electromagnetic wave source.
[0004] To improve matching, we need to monitor the matching status of the electromagnetic wave sources and adjust the parameters of the material being processed, mainly thickness, density, and humidity. For this purpose, directional couplers are commonly used to detect the power reflected back from the material. In microwave tunnel furnaces, the number of electromagnetic wave sources can be large. Equipping each source with a directional coupler and power display significantly increases manufacturing costs and occupies installation space. Furthermore, the directional coupler couples both forward and reverse propagating electromagnetic waves simultaneously. If weak coupling is used to extract a small amount of energy, such as one percent, the microwave energy reaching the material being processed is almost unaffected, resulting in minimal loss of energy efficiency for the micro-electromagnetic wave source. However, detectors and relays are needed to control the power supply to the electromagnetic wave source, leading to complex circuitry and further increasing manufacturing costs. If strong coupling is used to extract a larger amount of energy, such as one-tenth or more, a temperature control switch can be used for simple and effective control of the micro-electromagnetic wave source. However, the microwave energy reaching the material being processed will be significantly reduced, significantly decreasing the energy efficiency of the micro-electromagnetic wave source. Utility Model Content
[0005] To address the aforementioned deficiencies, this invention provides an electromagnetic wave feeding device, which aims to improve at least one of the problems mentioned in the background art.
[0006] The technical solution is: an electromagnetic wave feeding device, comprising an electromagnetic wave source, a transmission line, and at least one coupling structure. The electromagnetic wave source is connected to the transmission line and transmits electromagnetic wave energy through the transmission line, and the coupling structure is connected to the transmission line through the side of the transmission line.
[0007] The number of coupling structures here is generally one, but it can also be two or more.
[0008] The electromagnetic wave source can be connected to one end face of the transmission line or to one side face of the transmission line.
[0009] Preferably, the system further includes at least one heating element made of a wave-absorbing material that converts electromagnetic waves within the coupling structure into heat. The heating element is located inside the coupling structure or at one end away from the transmission line. The system also includes a heat sink, with the heating element in direct or indirect contact with the heat sink.
[0010] The function of the coupling structure is to couple with the electromagnetic waves of the transmission line, and the function of the heating element is to convert the electromagnetic waves in the coupling structure into heat. The heating element is made of electromagnetic wave absorbing materials such as graphite, silicon carbide, and water.
[0011] The core design concept of this utility model is as follows: In order to monitor the degree of matching, protect the electromagnetic wave source when mismatched, and attenuate reflected power when mismatched, it is proposed for the first time to use a coupling structure to couple out the electromagnetic wave energy reflected inside the transmission line and convert it into heat, thereby realizing the detection of reflected power. By adjusting the shape of the processed material, the matching of the electromagnetic wave source is improved, thereby increasing the energy efficiency of the electromagnetic wave source and protecting it. The prerequisite for these functions is the proposed conversion of the coupled reflected electromagnetic wave energy into heat.
[0012] In addition, since the heating element requires support, a heat sink can be used for support and heat dissipation. The heat sink can adopt other conventional structures or the coupling structure itself. The coupling structure plays a triple role in coupling electromagnetic waves, supporting the heating element, and dissipating heat from the heating element. Specifically, the coupling structure can act as a heat sink, with at least one heating element in direct contact with the wall of the coupling structure or indirect contact through a heat conductor; at least one dimension of the coupling structure in a direction perpendicular to the axis of the transmission line is greater than 0.4 times the operating wavelength of the electromagnetic wave.
[0013] Preferably, it also includes a temperature detector, which is directly mounted on the heating element or mounted on the indirect contact path between the heating element and the heat sink, or on the heat sink or the coupling structure.
[0014] Preferably, it also includes a temperature control switch connected in series in the electromagnetic wave source power supply circuit. The temperature control switch is directly mounted on the heating element or mounted on the indirect contact path between the heating element and the heat sink, or on the heat sink or the coupling structure.
[0015] Preferably, it also includes a cooling structure, which is directly mounted on the heating element or mounted on the indirect contact path between the heating element and the heat sink, or on the heat sink or on the coupling structure.
[0016] Because a mismatch can occur between the heated material and the electromagnetic wave source—for example, when materials of uneven thickness, such as tea leaves, are heated—this invention converts the electromagnetic waves coupled to the coupling structure, especially reflected electromagnetic waves, into heat to visually observe the mismatch. This heat is then directly reflected by a temperature detector, and the degree of mismatch is indicated by the current temperature reading. Similarly, to protect the equipment in cases of severe mismatch, this invention also innovatively proposes a temperature control switch to control the power supply circuit of the electromagnetic wave source. Likewise, to maintain equipment operation in cases of severe mismatch, this invention also innovatively proposes a cooling structure to dissipate heat from the heating element.
[0017] Specifically, electromagnetic waves here include various frequencies. The most widely used frequency in industrial and agricultural production is the microwave frequency.
[0018] Monitoring Function: A temperature detector can be installed outside the coupling structure. Increased reflection in the transmission line leads to increased electromagnetic wave power entering the coupling structure. This causes the heat-generating components within the coupling structure to heat up, raising the temperature of its outer shell. This temperature can be detected and displayed by the temperature detector on the coupling structure's outer shell. By monitoring the temperature of the coupling structure's outer shell, we can determine the matching status of the electromagnetic wave source in the transmission line.
[0019] Protection Function: We can also install a temperature control switch on the outer casing of the coupling structure, allowing the power supply line of the electromagnetic source to supply power to the electromagnetic source through the temperature control switch. When the mismatch in the transmission line is poor, the power entering the coupling structure is large, causing the outer casing temperature of the coupling structure to rise. The temperature control switch will then disconnect from the connected state, and the electromagnetic source will stop working. This prevents the electromagnetic source from being damaged due to long-term mismatch (serving as a protection action triggered by mismatch). After a period of time, when the temperature of the temperature control switch drops to a certain value, the temperature control switch will reconnect, and the electromagnetic source will start working again. In this way, we can protect the electromagnetic source by allowing it to operate intermittently.
[0020] Energy dissipation function: To prevent the electromagnetic wave source from being in a severely mismatched state when operating at high power, we can divert a portion of the higher-power electromagnetic waves through the coupling structure, thereby reducing the reflected power received by the electromagnetic wave source. At this time, some of the forward-transmitting electromagnetic wave power will also be coupled to the coupling structure, thus sacrificing the energy efficiency of the electromagnetic wave source to some extent. To reduce the temperature of the coupling structure, a cooling structure can be incorporated into it. A common cooling structure is a cooling pipe, which can be wound around the coupling structure and contact the outer shell of the coupling structure.
[0021] In a preferred design, the transmission line is a rectangular waveguide, and the coupling structure is a hollow rectangular metal tube containing a columnar metal body. The short side of the coupling structure's cross-section is parallel to the axis of the transmission line. This design allows for very low electromagnetic wave power entering the coupling structure during matching, while significantly increasing the power during severe mismatch. The position of the metal body near the transmission line can be adjusted and fixed outside the coupling structure. Sometimes, the metal body can penetrate the outer shell of the transmission line and extend into it to increase the coupled electromagnetic wave power on the coupling structure.
[0022] The simplest design is also the best design; here, there is only one columnar metal body. Of course, there can also be multiple. When using multiple columnar metal bodies, they should be parallel to each other.
[0023] In another design, both the coupling structure and the internal metal body are columnar, with the heating element located at the far end of the coupling structure, away from the transmission line. In this case, the heating element acts as a matching resistor. The electromagnetic wave power coupled from the transmission line is absorbed by the heating element, heating it. We can use a temperature detector to monitor the temperature of the heating element and thus the reflected power on the transmission line, or we can use a temperature control switch to shut off the power supply to the electromagnetic wave source when the reflected power on the transmission line becomes too high. After a period of time, the temperature of the heating element decreases, the temperature control switch reconnects, and the electromagnetic wave source resumes operation.
[0024] The length of the tubular coupling structure must be chosen such that all electromagnetic waves entering the coupling structure from the transmission line are absorbed by the heating element within the coupling structure without being reflected. Therefore, the lengths of both the coupling structure and the heating element should be sufficiently long: the length of the heating element in the axial direction of the coupling structure should be greater than two-thirds of the length of the coupling structure itself.
[0025] In a preferred design, the electromagnetic wave feed device has a mirror-symmetrical structure. The transmission line and the coupling structure are rectangular waveguides, and a columnar metal body is disposed inside the coupling structure.
[0026] The columnar metal body can be a screw, and the closer its tip is to the transmission line, the higher the electromagnetic wave power coupled from the transmission line through the coupling structure. The position of the columnar metal body in the coupling structure can be adjusted and fixed outside the coupling structure.
[0027] The location of the junction between the coupling structure and the transmission line is crucial. Preferably, the coupling structure is columnar, and the distance between its central axis and the crest of the electric field of the transmission line along the axial direction of the transmission line is less than 0.1 times the waveguide wavelength of the transmission line at the center frequency of the electromagnetic wave. Even more preferably, the central axis of the coupling structure coincides with the crest of the electric field of the transmission line along the axial direction of the transmission line.
[0028] The working principle of this utility model is described as follows:
[0029] We vertically insert a rectangular tubular coupling structure onto the transmission line, with the shorter side of the coupling structure's cross-section parallel to the axis of the transmission line. A columnar metal body is incorporated within the coupling structure. This columnar metal body is located within or passes through the coupling structure into the transmission line. The following objectives are achieved by selecting the cross-sectional dimensions of the coupling structure: When the transmission line is terminated with matching, due to the symmetry of the entire structure and the relatively small size of the coupling structure along the transmission line axis, the power coupled from the transmission line to the coupling structure is low, ensuring that the electromagnetic wave power coupled into the coupling structure is very small, for example, one percent. When the transmission line terminates with total internal reflection, because the coupling structure is located at the peak of the electric field on the transmission line, the standing wave in the transmission line will excite several times the power within the coupling structure, which is used to heat the heating element located within or at the top of the coupling structure. The heating element reaches the highest temperature.
[0030] When the reflection in the transmission line results in partial heating, the temperature of the heating element falls between the temperatures during matching and total reflection. Therefore, we can monitor the reflected power on the transmission line by detecting the temperature of the heating element.
[0031] Therefore, we have developed a simple transmission line reflection monitoring technology and an electromagnetic wave source protection technology.
[0032] This invention provides a coupling structure for reflected signals. The coupling structure is positioned at a specific location on a transmission line. One end of the transmission line is an electromagnetic wave source, and the other end is the material being processed. When the transmission line is in a matched state, the electromagnetic wave primarily propagates along the transmission line to the processed material, with only a small amount of energy entering the coupling structure, resulting in a very low temperature. When the transmission line experiences significant reflection, the electromagnetic wave in the transmission line exhibits a standing wave state. Because the coupling structure is located near the peak of the standing wave electric field in the transmission line, the electromagnetic wave entering the coupling structure has high energy and heats the coupling structure. Thus, a one-to-one correspondence is established between the temperature of the coupling structure and the reflected signal in the transmission line. The matched state of the electromagnetic wave source load can be displayed by monitoring the temperature at a point on the coupling structure. By changing the heated material, the matched load of the electromagnetic wave source can be achieved, increasing the energy efficiency of the electromagnetic wave source and protecting it from damage caused by radiant energy.
[0033] This invention can be used in various electromagnetic wave processing systems, such as household microwave ovens, industrial microwave ovens, and microwave tunnel ovens, for the expansion, sterilization, deep drying, and sintering of materials. Attached Figure Description
[0034] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of this utility model;
[0035] Figure 2 This is a schematic diagram of the overall structure of Embodiment 2 of this utility model;
[0036] Figure 3 This is a schematic diagram of the overall structure of Embodiment 3 of this utility model;
[0037] Figure 4 This is a schematic diagram of the overall structure of Embodiment 4 of this utility model.
[0038] Figure 5 This is a schematic diagram of the overall structure of Embodiment 5 of this utility model.
[0039] In the diagram, 1-electromagnetic wave source, 2-transmission line, 3-coupling structure, 4-metal body, 5-heating element, 6-temperature detector, 7-temperature control switch, 8-cooling structure, 9-material cavity. Detailed Implementation
[0040] The present invention will be further described below with reference to the accompanying drawings.
[0041] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal connection of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0042] In the description of this utility model, it should be understood that the terms "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model 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, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, "a plurality of" means two or more, unless otherwise precisely specified.
[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0044] The technical solution of this utility model will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.
[0045] In this invention, a temperature control switch, also known as a temperature controller, refers to a type of control element that opens or closes wires based on changes in the temperature of the working environment. It generally includes a temperature sensing part, a thermistor, and two wires. The temperature sensing part is in contact with the object being monitored. When the temperature change of the temperature sensing part reaches a critical value, the thermistor is triggered, causing the two wires to open or close.
[0046] Example 1
[0047] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the overall structure of this embodiment.
[0048] The technical solution is as follows: An electromagnetic wave feeding device includes an electromagnetic wave source 1, a transmission line 2, and a coupling structure 3. The electromagnetic wave source 1 is connected to the transmission line 2 and transmits electromagnetic wave energy through the transmission line 2. The coupling structure 3 is connected to the transmission line 2 through its side. The transmission line 2 is connected to the material cavity chamber 9 of the material being processed.
[0049] The electromagnetic wave source 1 is connected to one end face of the transmission line 2.
[0050] The electromagnetic waves here are microwaves.
[0051] A temperature detector 6 is installed outside the coupling structure 3.
[0052] The transmission line 2 is a waveguide, and the coupling structure 3 is a hollow metal tube with a metal body 4 inside. The metal body 4 passes through the outer shell of the transmission line 2 and extends into the transmission line 2.
[0053] A heating element 5 is provided in the coupling structure 3.
[0054] The length of the heating element 5 in the axial direction of the coupling structure 3 is greater than two-thirds of the length of the coupling structure 3.
[0055] The coupling structure 3 is columnar, and the distance between the central axis of its cross-section and the peak of the electric field of the transmission line 2 in the axial direction of the transmission line 2 is less than 0.1 times the waveguide wavelength of the transmission line 2 at the center frequency of the electromagnetic wave.
[0056] Example 2
[0057] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the overall structure of this embodiment.
[0058] Compared to Example 1, the only difference is that the electromagnetic wave source 1 is located on the side of the transmission line 2. The transmission line 2 is a rectangular waveguide, the coupling structure 3 is a circular waveguide, and the metal body 4 is a circular metal rod. Two heating elements 5 are located on both sides of the metal body 4 in the coupling structure 3. The entire electromagnetic wave feeding device has a mirror-symmetric structure. No temperature detector 6 is located on the outside of the coupling structure 3, but a temperature control switch 7 is provided. The temperature control switch 7 is connected in series with the power line of the electromagnetic wave source 1.
[0059] Example 3
[0060] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the overall structure of this embodiment.
[0061] Compared to Example 2, the only difference is that no temperature control switch 7 is provided. A cooling structure 8, specifically a cooling water pipe, is provided outside the coupling structure 3. The heat generated by the coupling structure 3 is carried away by the cooling water in the cooling water pipe, thereby preventing overheating.
[0062] Example 4
[0063] Please refer to Figure 4 , Figure 4 This is a schematic diagram of the overall structure of this embodiment.
[0064] The only difference from Embodiment 2 is that we have provided two coupling structures 3. The two coupling structures 3 are respectively disposed on the upper and lower surfaces of the transmission line 2. A temperature detector 6 is disposed on the surface of one coupling structure 3, and a temperature control switch 7 is disposed on the surface of the other coupling structure 3.
[0065] Implementation Example 5
[0066] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the overall structure of this embodiment.
[0067] Transmission line 1 is a standard BJ26 rectangular waveguide with a cross-sectional area of 86.36 mm wide and 43.16 mm narrow. Coupling structure 3 is also a rectangular waveguide with a cross-sectional area of 26 mm wide and 10 mm narrow. The metal body 4 in the coupling structure is a 5.6 mm diameter metal pillar. This pillar is inserted 4.7 mm into transmission line 1. The distance from the axis of the metal pillar to the open end of the transmission line is 41.74 mm. Simulation results show that, assuming the electromagnetic wave power generated by the electromagnetic source is 1000 watts, when the open end of the transmission line is matched, the power coupled to the coupling structure within the operating bandwidth of 2.4 GHz to 2.5 GHz is approximately 10 watts. When the open end of the transmission line is short-circuited, the power coupled to the coupling structure is approximately 40 watts.
[0068] Therefore, it can be inferred that as the matching state at the open end of the transmission line changes from matched to total reflection, the power on the coupling structure monotonically increases from 10 watts to 40 watts. This power will be used to heat the heating elements located inside or at the top of the coupling structure, resulting in different temperatures. Thus, we can monitor the reflection coefficient at the open end of the transmission line by monitoring the temperature of the heating elements.
[0069] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. An electromagnetic wave feeding device, comprising an electromagnetic wave source (1), a transmission line (2), and at least one coupling structure (3), characterized in that, The electromagnetic wave source (1) is connected to the transmission line (2) and transmits electromagnetic wave energy through the transmission line (2). The coupling structure (3) is connected to the transmission line (2) through the side of the transmission line (2).
2. The electromagnetic wave feeding device according to claim 1, characterized in that, It also includes at least one heating element (5) made of wave-absorbing material that converts electromagnetic waves inside the coupling structure (3) into heat.
3. The electromagnetic wave feeding device according to claim 2, characterized in that, The heating element (5) is located inside the coupling structure (3) or at one end away from the transmission line (2).
4. The electromagnetic wave feeding device according to claim 2, characterized in that, It also includes a heat sink, and the heat source (5) is in direct or indirect contact with the heat sink.
5. An electromagnetic wave feeding device according to claim 2, characterized in that, The coupling structure (3) serves as a heat sink, and at least one heat-generating element (5) is in direct contact with the wall of the coupling structure (3) or indirect contact through a heat conductor; at least one of the coupling structures (3) has a dimension in a direction perpendicular to the axis of the transmission line (2) that is greater than 0.4 times the working wavelength of the electromagnetic wave.
6. An electromagnetic wave feeding device according to any one of claims 2-5, characterized in that, It also includes a temperature detector (6), which is directly mounted on the heating element (5) or on the indirect contact path between the heating element (5) and the heat sink, or on the heat sink or on the coupling structure (3).
7. An electromagnetic wave feeding device according to any one of claims 2-5, characterized in that, It also includes a temperature control switch (7) connected in series in the power supply circuit of the electromagnetic wave source (1). The temperature control switch (7) is directly mounted on the heating element (5) or mounted on the indirect contact path between the heating element (5) and the heat sink or on the heat sink or on the coupling structure (3).
8. An electromagnetic wave feeding device according to any one of claims 2-5, characterized in that, It also includes a cooling structure (8), which is directly mounted on the heating element (5) or mounted on the indirect contact path between the heating element (5) and the heat sink or on the heat sink or on the coupling structure (3).
9. An electromagnetic wave feeding device according to any one of claims 1-5, characterized in that, The transmission line (2) and the coupling structure (3) are rectangular waveguides, and a columnar metal body (4) is provided inside the coupling structure (3); the length of the heating element (5) in the coupling structure (3) in the axial direction of the coupling structure (3) is greater than two-thirds of the length of the metal body (4).
10. An electromagnetic wave feeding device according to any one of claims 1-5, characterized in that, The electromagnetic wave feeding device is a mirror-symmetric structure; the short side of the cross-section of the rectangular tubular coupling structure (3) is parallel to the axial direction of the transmission line (2); the coupling structure (3) is columnar, and the distance between the central axis of its cross-section and the peak of the electric field of the transmission line (2) in the axial direction of the transmission line (2) is less than 0.1 times the waveguide wavelength of the transmission line (2) at the center frequency of the electromagnetic wave.