Heating body with electromagnetic heating and resistance heating functions

Abstract

The utility model relates to a kind of heating body with electromagnetic heating and resistance heating function, including the paste-like paint with electromagnetic heating and resistance heating function, insulating heat-conducting plate and electrode, the paste-like paint printing coating is formed composite heating film on the insulating heat-conducting plate surface, the electrode is set on the insulating heat-conducting plate surface and with the composite heating film electric connection.This heating body simultaneously has electromagnetic heating and resistance heating function in same structure, by controlling input current type or frequency, can flexibly select to heat with electromagnetic induction or resistance joule effect, to realize double-mode controllable heating.It has high structure integration, without respectively setting electromagnetic coil and resistance heating piece, significantly simplify system structure and manufacturing process.

Description

Technical Field

[0001] This utility model relates to a heating element that combines electromagnetic heating and resistive heating functions. Background Technology

[0002] Existing heating technologies are mainly divided into two categories: electromagnetic induction heating and resistance heating. The former relies on high-frequency magnetic fields to generate eddy currents and hysteresis losses in magnetically conductive metals. It heats up quickly but is sensitive to the material of the heated body and coupling conditions. Non-metallic or weakly magnetic carriers are difficult to heat efficiently. The latter utilizes the Joule effect, is compatible with a wide range of materials, and is simple to control, but has greater thermal inertia and is limited in energy efficiency and temperature uniformity. In existing products and publicly available solutions, only a single mechanism is generally used, or two independent heating units are placed in parallel within the same device, which has problems such as structural dispersion, increased volume and cost, fragmented heat paths, and complex control. There is still a lack of solutions that can achieve both electromagnetic heating and resistive heating in the same heating element or even the same film layer. Utility Model Content

[0003] The purpose of this invention is to provide a heating element that combines and synergistically integrates electromagnetic heating and resistive heating.

[0004] The purpose of this utility model is achieved as follows: A heating element that combines electromagnetic heating and resistive heating functions includes a viscous coating, an insulating heat-conducting plate, and electrodes. The viscous coating is printed and coated on the surface of the insulating heat-conducting plate to form a composite heating film. The electrodes are disposed on the surface of the insulating heat-conducting plate and electrically connected to the composite heating film.

[0005] This heating element integrates both electromagnetic and resistive heating functions within a single structure. By controlling the type or frequency of the input current, it can flexibly select between electromagnetic induction and resistive Joule effect for heating, thus achieving dual-mode controllable heating. Its high structural integration eliminates the need for separate electromagnetic coils and resistive heating elements, significantly simplifying system construction and manufacturing processes. Compared to traditional single heating mechanisms, this design achieves efficient electromagnetic heating on metallic substrates and uniform heating via resistance on non-metallic or weakly magnetic materials, expanding its applicability, improving thermal response speed and temperature control accuracy, and balancing high energy efficiency and reliability.

[0006] The objective of this utility model can also be achieved by the following technical measures: Furthermore, the insulating heat-conducting plate is provided with printed guide lines, and the viscous coating is printed on the printed guide lines to form the composite heating film.

[0007] By setting printed guide lines on the insulating heat-conducting plate, the viscous coating can be filmed along a predetermined path, which can significantly reduce line width / spacing deviation, ensure repeatability of equivalent resistance and inductance parameters, and achieve more uniform current distribution, thus suppressing local overcurrent and hot spots from the source. At the same time, it facilitates online detection and mass production control, improving consistency, yield and long-term reliability.

[0008] Furthermore, the printed guide line is a coil-shaped printed guide line.

[0009] When energized, the coil-shaped pattern forms a concentrated and controllable alternating magnetic field, which improves the electromagnetic coupling efficiency to the metal carrier. At the same time, it extends the conductive path and increases the equivalent resistance, making it easier for Joule heating to spread evenly. This achieves the synergy of electromagnetic and resistive mechanisms, taking into account both rapid heating and temperature uniformity.

[0010] Furthermore, the coil-shaped printed guide line is a circular coil-shaped printed guide line or a square coil-shaped printed guide line.

[0011] Circular coils are advantageous for obtaining an axisymmetric magnetic / temperature field and have good temperature uniformity at the center; square coils have high area utilization and sufficient coverage of the edges and corners, making them easy to match with rectangular cavities or plate-type heating surfaces; the choice of these two forms enhances the structural adaptability and overall design freedom, helping to achieve higher energy efficiency and temperature field consistency in different applications.

[0012] Furthermore, the electrode includes a positive electrode and a negative electrode. The insulating heat-conducting plate is provided with a positive electrode positioning point at the entrance position of the printed guide line, and the positive electrode is located at the positive electrode positioning point. The insulating heat-conducting plate is provided with a negative electrode positioning point at the exit position of the printed guide line, and the negative electrode is located at the negative electrode positioning point.

[0013] Setting positive and negative electrode positioning points at the inlet / outlet of the guide wire ensures that the connection position between the electrode and the heating film is stable and repeatable, reduces contact resistance and current congestion, and lowers the risk of end overheating and failure; at the same time, it facilitates automated placement and subsequent interconnection, improving assembly efficiency and product consistency.

[0014] Furthermore, the positive electrode is a silver paste electrode, which is screen-printed onto the positive electrode positioning point of the insulating heat-conducting plate, and the thickness of the positive electrode is 5–30 μm; The negative electrode is a silver paste electrode, which is screen-printed onto the negative electrode positioning point of the insulating heat-conducting plate, and the thickness of the negative electrode is 5–30 μm.

[0015] The silver paste electrodes are formed by screen printing with a thickness controlled in the range of 5–30 μm, which can achieve a balance between low sheet resistance and high conductivity reliability. The thickness is sufficient to provide good adhesion and mechanical strength, while avoiding stress peeling and cost increases caused by excessive thickness. It is beneficial for welding / conductive adhesive connection, reducing contact loss and extending life.

[0016] Furthermore, the insulating heat-conducting plate is a ceramic plate or a metal plate with an insulating heat-conducting layer on its surface.

[0017] Ceramic substrates or metal plates covered with insulating and thermally conductive layers combine high dielectric strength and low thermal resistance, ensuring electrical safety isolation while quickly conducting heat to the heated surface, adapting to high power density and long-term operation; the flexibility in material selection also facilitates optimization between thinness, temperature shock resistance and cost.

[0018] Furthermore, the viscous coating includes a coating formulation and an adhesive that have the functions of generating a magnetic field and generating heat, wherein the coating formulation and the adhesive are mixed to form the viscous coating.

[0019] The coating formulation and adhesive work together to create a film that has both a conductive network to generate Joule heating and can efficiently establish a magnetic field under alternating current in conjunction with a coil structure, achieving dual-mechanism heating. The adhesive improves the density and adhesion of the coating, enhances its resistance to damp heat and aging, and ensures long-term stable output.

[0020] Furthermore, the thickness of the composite heating film is 10–100 μm.

[0021] By controlling the composite heating film within the range of 10–100 μm, it is possible to balance sheet resistance, dielectric strength, interfacial thermal resistance, and printability: thin films have fast response and low thermal resistance; thick films have better voltage resistance and mechanical strength, and can effectively suppress pinhole breakdown and edge carbonization, thereby improving safety and reliability.

[0022] Furthermore, the line width of the coil-shaped printed guide line is 0.2–0.8 mm, the spacing between adjacent lines is 0.2–1.2 mm, and the number of coil turns is 5–40 turns; the positive electrode and the coil start point, and the negative electrode and the coil end point are respectively overlapped with the composite heating film with an overlap length of 0.5–2.0 mm; and an uncoated insulating isolation strip with a width of 0.5–2.0 mm is left along the circumference of the outer edge of the composite heating film.

[0023] The parameter window of 0.2–0.8 mm line width, 0.2–1.2 mm spacing, and 5–40 turns allows for precise matching of inductance and resistance according to target power and frequency band, achieving efficient coupling and uniform temperature; the 0.5–2.0 mm overlap between the electrode and coil end significantly reduces contact resistance and current spikes; the 0.5–2.0 mm circumferential insulation strip on the outer edge increases creepage distance and withstand voltage margin, reduces edge discharge and EMC risks, and improves overall safety and yield.

[0024] The beneficial effects of this utility model are as follows: This invention's heating element possesses both electromagnetic and resistive heating functions. By controlling the type or frequency of the input current, it can flexibly select between electromagnetic induction and resistive Joule effect heating, thus achieving dual-mode controllable heating. Its high structural integration eliminates the need for separate electromagnetic coils and resistive heating elements, significantly simplifying system construction and manufacturing processes. Compared to traditional single heating mechanisms, this design can achieve efficient electromagnetic heating on metallic substrates and uniform heating via resistance on non-metallic or weakly magnetic materials, expanding its applicability, improving thermal response speed and temperature control accuracy, and balancing high energy efficiency and reliability. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the heating element in Example 1.

[0026] Figure 2 This is a schematic diagram of the heating element in Example 2. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments: Example 1, combined with Figure 1 As shown, a heating element that combines electromagnetic heating and resistive heating functions includes a viscous coating that combines electromagnetic heating and resistive heating functions, an insulating heat-conducting plate 2, and electrodes. The viscous coating is printed and coated on the surface of the insulating heat-conducting plate 2 to form a composite heating film 1. The electrodes are disposed on the surface of the insulating heat-conducting plate 2 and electrically connected to the composite heating film 1.

[0028] Furthermore, the insulating heat-conducting plate 2 is provided with printed guide lines, and the viscous coating is printed on the printed guide lines to form the composite heating film 1.

[0029] Furthermore, the printed guide line is a coil-shaped printed guide line.

[0030] Furthermore, the coil-shaped printed guide line is a circular coil-shaped printed guide line.

[0031] Furthermore, the electrode includes a positive electrode 3 and a negative electrode 4. The insulating heat-conducting plate 2 is provided with a positive electrode positioning point at the entrance position of the printed guide line, and the positive electrode 3 is located at the positive electrode positioning point. The insulating heat-conducting plate 2 is provided with a negative electrode positioning point at the exit position of the printed guide line, and the negative electrode 4 is located at the negative electrode positioning point.

[0032] Furthermore, the positive electrode 3 is a silver paste electrode, which is screen-printed on the positive electrode positioning point of the insulating heat-conducting plate 2, and the thickness of the positive electrode 3 is 5–30 μm; The negative electrode 4 is a silver paste electrode, which is screen-printed on the negative electrode positioning point of the insulating heat-conducting plate 2, and the thickness of the negative electrode 4 is 5–30 μm.

[0033] Furthermore, the insulating heat-conducting plate 2 is a ceramic plate or a metal plate with an insulating heat-conducting layer on its surface.

[0034] Furthermore, the viscous coating includes a coating formulation and an adhesive that have the functions of generating a magnetic field and generating heat, wherein the coating formulation and the adhesive are mixed to form the viscous coating.

[0035] Furthermore, the thickness of the composite heating film 1 is 10–100 μm.

[0036] Furthermore, the line width of the coil-shaped printed guide line is 0.2–0.8 mm, the spacing between adjacent lines is 0.2–1.2 mm, and the number of coil turns is 5–40 turns; the positive electrode 3 and the coil start point, and the negative electrode 4 and the coil end point are respectively overlapped with the composite heating film 1 with an overlap length of 0.5–2.0 mm; and an uncoated insulating isolation strip with a width of 0.5–2.0 mm is left along the circumference of the outer edge of the composite heating film 1.

[0037] The viscous coating comprises Cu, Sn, P, Fe, Si, Ag, and Zn, wherein each component is expressed as follows by mass percentage: Cu 60–70 wt%, Sn 0.005–0.05 wt%, P 0.001–0.01 wt%, Fe 0.005–0.05 wt%, Si 0.001–0.02 wt%, Ag 0.001–0.05 wt%, and Zn 30–40 wt%, and the total of all components is 100 wt%.

[0038] Example 2, combined with Figure 2 As shown, the difference between Example 2 and Example 1 is that the circular printed guide line in Example 2 is a square coil printed guide line.

[0039] Resistance heating: When the user adjusts the controller to DC or low-frequency PWM mode, current flows through the composite heating film 1, generating Joule heat. The heat is rapidly conducted to the bottom of the pot through the insulating heat-conducting plate 2, achieving uniform surface heating. This mode has almost no restrictions on the material of the pot; non-magnetic pots such as glass, ceramic, aluminum, and copper can all be used. It is also insensitive to the placement of the pot, resulting in more even heating and more stable temperature control, making it particularly suitable for precise temperature control scenarios such as heat preservation and slow cooking.

[0040] Electromagnetic heating: When the user adjusts the controller to high-frequency AC mode, the coil-like structure inside the composite heating film 1 generates an alternating magnetic field, which induces eddy currents and hysteresis losses at the bottom of ferromagnetic cookware such as stainless steel and cast iron, allowing heat to be generated directly inside the pot. This mode features rapid heating, high thermal efficiency, and sensitive response, resulting in more concentrated and even heating of the food. At the same time, the heating element itself experiences a lower temperature rise, ensuring better safety and lower energy consumption, making it particularly suitable for cooking methods that require high heat, such as stir-frying and quick boiling.

[0041] The composite heating film 1 achieves resistance heating or electromagnetic heating based on the following principle: A composite heating film with both high conductivity and certain magnetic response is formed by printing / curing a viscous coating mainly composed of Cu (60–70 wt%) and Zn (30–40 wt%), doped with Sn, P, Fe, Si, and Ag. Cu and a small amount of Ag form a continuous conductive network, Zn adjusts the sheet resistance and temperature coefficient and improves oxidation resistance, trace amounts of Fe increase the relative permeability to facilitate magnetic field concentration, Sn improves sintering wetting and grain boundary bonding, and P and Si play a role in deoxidation / solution strengthening to stabilize the microstructure.

[0042] When the controller outputs DC or low-frequency PWM, the current flows along the coil-shaped trace in the network, generating Joule heat, which is then transferred to the bottom of the pot via the insulating heat-conducting plate 2, manifesting as resistance heating. When the controller switches to high-frequency AC, the coil-shaped traces establish an alternating magnetic field in the conductive / magnetic film and form a surface current distribution under the influence of the skin effect, electromagnetically coupling energy to the bottom of the ferromagnetic pot to induce eddy currents and hysteresis losses. Heat is generated directly inside the pot, which manifests as electromagnetic heating.

[0043] Therefore, by simply adjusting the shape / frequency of the input current, switchable operation of both resistive and electromagnetic heating mechanisms can be achieved on the same composite heating film 1.

[0044] In other embodiments, the viscous coating comprises Cu, Cr, Al, Mn, Si, Mg, Fe, and Ag, wherein the components are expressed as follows by mass percentage: Cu 90–99 wt%, Cr 0.5–2.5 wt%, Al 1–3 wt%, Mn 0.05–0.3 wt%, Si 0.01–0.1 wt%, Mg 0.001–0.05 wt%, Fe 0.005–0.05 wt%, and Ag 0.01–0.05 wt%, and the total of all components is 100 wt%.

[0045] The composite heating film 1 achieves resistance heating or electromagnetic heating based on the following principle: Using Cu (90–99 wt%) as the continuous conductive phase, supplemented with small amounts of Cr (0.5–2.5 wt%), Al (1–3 wt%), Mn, Si, Mg, Fe and Ag for microalloying, a dense, highly adhesive and conductive composite heating film is formed after printing and curing. Cu and trace amounts of Ag construct a low sheet resistance conductive network and improve wetting / interconnection. Cr and Al easily form a dense oxide layer at the interface to enhance oxidation resistance and film-substrate bonding. Mn / Si is beneficial for grain refinement and stable resistance. Mg plays a deoxidizing role. A small amount of Fe increases the relative permeability to facilitate the concentration and coupling of alternating magnetic fields.

[0046] Its working principle is as follows: When the controller outputs DC or low-frequency PWM, the current flows in a closed loop within the membrane along the coil-shaped trace, generating Joule heat according to P=I²RP=I²RP=I²R, which is then transferred to the bottom of the pot via the insulating heat-conducting plate 2, thus achieving resistive heating. When the controller switches to high-frequency AC, the coil-shaped traces establish an alternating magnetic field inside the membrane. The membrane acts as an excitation coil, coupling energy to the bottom of the ferromagnetic pot, inducing eddy currents and accompanied by hysteresis loss, so that heat is generated directly inside the vessel, realizing electromagnetic heating (the membrane itself mainly undertakes the excitation and transmission of the field due to the skin effect and low magnetic loss).

[0047] Therefore, by simply adjusting the shape / frequency of the input current, switchable operation of resistance heating and electromagnetic heating can be achieved on the same composite heating film 1.

Claims

1. A heating element that combines electromagnetic heating and resistive heating functions, comprising a viscous coating that combines electromagnetic heating and resistive heating functions, an insulating heat-conducting plate, and electrodes, characterized in that: The viscous coating is printed and coated on the surface of the insulating heat-conducting plate to form a composite heating film, and the electrode is disposed on the surface of the insulating heat-conducting plate and electrically connected to the composite heating film.

2. The heating element with both electromagnetic and resistive heating functions according to claim 1, characterized in that: The insulating heat-conducting plate is provided with printed guide lines, and the viscous coating is printed on the printed guide lines to form the composite heating film.

3. The heating element with both electromagnetic and resistive heating functions according to claim 1, characterized in that: The printed guide line is a coil-shaped printed guide line.

4. The heating element with both electromagnetic heating and resistive heating functions according to claim 3, characterized in that: The coil-shaped printed guide line can be a circular coil-shaped printed guide line or a square coil-shaped printed guide line.

5. The heating element with both electromagnetic heating and resistive heating functions according to claim 1, characterized in that: The electrode includes a positive electrode and a negative electrode. The insulating heat-conducting plate is provided with a positive electrode positioning point at the entrance position of the printed guide line, and the positive electrode is located at the positive electrode positioning point. The insulating heat-conducting plate is provided with a negative electrode positioning point at the exit position of the printed guide line, and the negative electrode is located at the negative electrode positioning point.

6. The heating element with both electromagnetic heating and resistive heating functions according to claim 5, characterized in that: The positive electrode is a silver paste electrode, which is screen-printed onto the positive electrode positioning point of the insulating heat-conducting plate, and the thickness of the positive electrode is 5–30 μm. The negative electrode is a silver paste electrode, which is screen-printed onto the negative electrode positioning point of the insulating heat-conducting plate, and the thickness of the negative electrode is 5–30 μm.

7. The heating element with both electromagnetic and resistive heating functions according to claim 1, characterized in that: The insulating heat-conducting plate is a ceramic plate or a metal plate with an insulating heat-conducting layer on its surface.

8. The heating element with both electromagnetic heating and resistive heating functions according to claim 1, characterized in that: The viscous coating includes a coating formulation and an adhesive that have the functions of generating a magnetic field and generating heat, wherein the coating formulation and the adhesive are mixed to form the viscous coating.

9. The heating element with both electromagnetic heating and resistive heating functions according to claim 1, characterized in that: The thickness of the composite heating film is 10–100 μm.

10. The heating element with both electromagnetic heating and resistive heating functions according to claim 3, characterized in that: The coil-shaped printed guide line has a line width of 0.2–0.8 mm, an adjacent line spacing of 0.2–1.2 mm, and a coil turn count of 5–40 turns; the positive electrode and the coil start point, and the negative electrode and the coil end point, are respectively overlapped with the composite heating film with an overlap length of 0.5–2.0 mm; and an uncoated insulating isolation strip with a width of 0.5–2.0 mm is left along the circumference of the outer edge of the composite heating film.

Images