CN106958806B

CN106958806B - Steam generator and steam heating equipment

Info

Publication number: CN106958806B
Application number: CN201710210134.XA
Authority: CN
Inventors: 司鹏; 周宇; 陈茂顺; 黄志飞
Original assignee: Midea Group Co Ltd; Guangdong Midea Kitchen Appliances Manufacturing Co Ltd
Current assignee: Midea Group Co Ltd; Guangdong Midea Kitchen Appliances Manufacturing Co Ltd
Priority date: 2017-03-31
Filing date: 2017-03-31
Publication date: 2020-04-07
Anticipated expiration: 2037-03-31
Also published as: CN106958806A

Abstract

The invention discloses a steam generator and steam heating equipment, wherein the steam generator comprises a cavity and an electric heating element, the cavity is provided with a steam generating chamber, the steam generator comprises a water spray nozzle positioned at the upper end of the cavity, the water spray nozzle is communicated with the steam generating chamber, the electric heating element is arranged on the cavity, the electric heating element comprises a heat-conducting substrate and an electric heating film, the electric heating film is fixed on one side of the substrate, the substrate separates the electric heating film and the steam generating chamber, the substrate comprises a flow guide surface positioned in the steam generating chamber, the water spray nozzle faces the flow guide surface, and a layer of heat-conducting concave-convex structure is formed on the flow guide surface. The concave-convex structure increases the surface area of the flow guide surface, so that when water sprayed to the flow guide surface from the water spray nozzle flows along the concave-convex structure on the flow guide surface, the concave-convex structure can improve the effective area of heat transfer between the electric heating film and the water, thereby improving the steam generation efficiency of the steam generator.

Description

Steam generator and steam heating equipment

Technical Field

The invention relates to the technical field of steam heating, in particular to a steam generator and steam heating equipment.

Background

In the related art, the steam generator heats water into steam to heat by directly contacting the water with an electric heating element. However, the existing electric heating element has a small effective area for heat transfer with water, so that the steam generator has low steam generation efficiency.

Disclosure of Invention

The present invention has been made to solve at least one of the problems occurring in the related art. Therefore, the present invention is to provide a steam generator and a steam heating apparatus.

The steam generator comprises a cavity and an electric heating element, wherein the cavity is provided with a steam generating chamber, the steam generator comprises a water spraying opening positioned at the upper end of the cavity, the water spraying opening is communicated with the steam generating chamber, the electric heating element is installed on the cavity, the electric heating element comprises a heat-conducting substrate and an electric heating film, the electric heating film is fixed on one side of the substrate, the substrate separates the electric heating film and the steam generating chamber, the substrate comprises a flow guide surface positioned in the steam generating chamber, the water spraying opening faces the flow guide surface, and a layer of heat-conducting concave-convex structure is formed on the flow guide surface.

In the steam generator of the embodiment of the invention, the layer of heat-conducting concave-convex structure is formed on the flow guide surface, and the concave-convex structure increases the surface area of the flow guide surface, so that when water sprayed to the flow guide surface from the water spray nozzle flows along the concave-convex structure on the flow guide surface, the concave-convex structure can increase the effective area of heat transfer between the electric heating film and the water, thereby increasing the steam generation efficiency of the steam generator.

In one embodiment, the relief structure is a layered structure formed on the flow guide surface, the relief structure completely covering the flow guide surface.

In one embodiment, the concave-convex structure comprises a plurality of water storage grooves which are concave relative to the diversion surface, and the water storage grooves are arranged at intervals.

In one embodiment, the flow guiding surface is formed into the concave-convex structure by a surface modification process.

In one embodiment, the electrical heating element comprises a thermally conductive, hydrophilic coating covering the flow guiding surface and the surface of the relief structure.

In one embodiment, the shape of the coating layer matches the shape of the flow guiding surface and the shape of the relief structure.

In one embodiment, the water jets are slit-shaped.

In one embodiment, the water jet comprises a plurality of jets, the plurality of jets being spaced apart.

In one embodiment, a side of the flow guide surface adjacent to the water jet is inclined with respect to the cavity in a direction away from the cavity.

In one embodiment, the projection of the steam generating chamber on the side surface of the cavity is a right trapezoid structure, and the projection of the flow guide surface on the side surface of the cavity forms a long side waist of the right trapezoid structure.

In one embodiment, the electrical heating element comprises an insulated thermally conductive layer, the electrical heating film comprises an electrical resistance circuit, the thermally conductive layer connects the substrate and the electrical resistance circuit, the thermally conductive layer comprises a first thermally conductive layer and at least one second thermally conductive layer, the electrical resistance circuit and the first thermally conductive layer are stacked in sequence on the substrate.

In one embodiment, the resistor circuit includes a plurality of sub-resistor circuits, the plurality of sub-resistor circuits are arranged at intervals, and the plurality of sub-resistor circuits are connected in parallel.

A steam heating apparatus of an embodiment of the present invention includes the steam generator of any of the above embodiments.

In the steam heating device of the embodiment of the invention, the layer of heat-conducting concave-convex structure is formed on the flow guide surface, and the concave-convex structure increases the surface area of the flow guide surface, so that when water sprayed to the flow guide surface from the water spray nozzle flows along the concave-convex structure on the flow guide surface, the concave-convex structure can increase the effective area of heat transfer between the electric heating film and the water, thereby improving the steam generation efficiency of the steam generator.

Additional aspects and advantages of embodiments of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic plan view of a steam generator according to an embodiment of the present invention.

Fig. 2 is another schematic plan view of a steam generator according to an embodiment of the present invention.

Fig. 3 is still another schematic plan view of the steam generator according to the embodiment of the present invention.

Fig. 4 is an exploded schematic view of a steam generator according to an embodiment of the present invention.

Fig. 5 is a schematic perspective view of a cavity of a steam generator according to an embodiment of the present invention.

Fig. 6 is an enlarged schematic view of a portion i of the steam generator of fig. 5.

Fig. 7 is a schematic structural view of an electric heating element of a steam generator according to an embodiment of the present invention.

Fig. 8 is an exploded schematic view of an electric heating element of a steam generator according to an embodiment of the present invention.

Fig. 9 is a schematic sectional view of an electric heating element of a steam generator according to an embodiment of the present invention.

Fig. 10 is a schematic plan view of a coating and flow directing surface of a steam generator according to an embodiment of the present invention.

Fig. 11 is a schematic view of the structure of an electric heating film of an electric heating element of a steam generator according to an embodiment of the present invention.

Description of the main element symbols:

a steam generator 100;

the steam generator comprises a cavity 10, a side surface 101, a steam generating chamber 11, a water spray port 12, an air outlet 13, an air outlet pipe 131, a first side plate 14, a second side plate 15, a mounting surface 151 and a fixing interface 152;

the electric heating element 20, the substrate 21, the electric heating film 22, the current guiding surface 23, the surface 231, the current guiding surface 23a, the coating 24, the concave-convex structure 25a, the water storage tank 251, the heat conducting layer 26, the first heat conducting layer 261, the second heat conducting layer 262, the resistance circuit 27, the sub-resistance circuit 271, the electric conducting medium 272 and the electrode 28;

a water inlet pipe 30 and a water inlet 31.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected unless otherwise explicitly stated or limited. Either mechanically or electrically. Either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Referring to fig. 1 to 8, a steam generator 100 according to an embodiment of the present invention includes a chamber 10 and an electric heating element 20.

The cavity 10 is opened with a steam generating chamber 11, the steam generator 100 comprises a water spraying port 12 positioned at the upper end of the cavity 10, the water spraying port 12 is communicated with the steam generating chamber 11, and the electric heating element 20 is installed on the cavity 10. The electric heating element 20 comprises a heat-conducting substrate 21 and an electric heating film 22, the electric heating film 22 is fixed on one side of the substrate 21, the substrate 21 separates the electric heating film 22 and the steam generating chamber 11, the substrate 21 comprises a flow guide surface 23 located in the steam generating chamber 11, the water spray opening 12 faces the flow guide surface 23, and a heat-conducting concave-convex structure 25 is formed on the flow guide surface 23.

In the steam generator 100 according to the embodiment of the present invention, the heat-conductive concave-convex structure 25 is formed on the flow guide surface 23. The concave-convex structure 25 increases the surface area of the guiding surface 23, so that when the water sprayed from the water spraying opening 12 to the guiding surface 23 flows along the concave-convex structure 25 on the guiding surface 23, the concave-convex structure 25 can increase the effective area of the electric heating film 22 for heat transfer with the water, thereby increasing the steam generation efficiency of the steam generator 100.

The uneven structure 25 may be uneven with respect to the flow guide surface 23, and the uneven structure 25 may be sufficiently covered by water flowing over the uneven structure 25. Meanwhile, the concave-convex structure 25 can prolong the time of water flowing, so that the time of heat exchange between the water and the electric heating film 22 can be further increased, and the water can be sufficiently heated.

It will be appreciated that the configuration of the relief structure 25 may be arranged as the case may be. The concave-convex structure 25 may include a concave portion relative to the flow guiding surface 23, or a convex portion relative to the flow guiding surface 23, as long as water can cover the concave-convex structure 25. Preferably, the relief structure 25 comprises a portion that is concave with respect to the flow-guiding surface 23. The other part of the relief structure 25 is relatively flat with respect to the flow guide surface 23. Thus, the channeling phenomenon can be avoided when the water flow is small.

In some examples, the relief structure 25 is comprised of a thermally conductive material, such as a metallic material or a ceramic material.

Referring to fig. 9, in one embodiment, the concave-convex structure 25 includes a plurality of water storage grooves 251 that are concave relative to the diversion surface 23. The plurality of water storage tanks 251 are provided at intervals.

Thus, the water storage tank 251 can store part of the water, so that the residence time of more water on the concave-convex structure 25 and the diversion surface 23 is longer, and the heat exchange time between the water and the electric heating film 22 is further increased.

In one embodiment, the flow guide surface 23 is formed with a relief structure 25 by a surface modification process.

Thus, the concave-convex structure 25 is tightly combined with the flow guide surface 23, and the concave-convex structure 25 is easily formed by the surface modification process.

The surface modification process refers to forming the concave-convex structure 25 on the flow guide surface 23 by a physical or chemical surface modification method. For example, in some examples, the concave-convex structure 25 is formed on the diversion surface 23 by a surface modification process such as an etching method or an embossing method, wherein the etching method may be a physical sputtering method or an electrochemical etching method.

In one embodiment, the electrical heating element 20 includes a thermally conductive, hydrophilic coating 24. The coating 24 covers the flow guide surface 23 and the surface of the concave-convex structure 25.

Thus, since the heat-conductive hydrophilic coating 24 is formed on the flow guide surface 23 and the concave-convex structure 25, when the water sprayed from the water spray 12 to the flow guide surface 23 flows along the coating 24 on the flow guide surface 23, the water can be effectively adsorbed on the coating 24 and can form a water film on the coating 24, so that the heat generated at each position of the electric heating film 22 can be sufficiently absorbed by the water on the coating 24, thereby effectively preventing the electric heating film 22 from generating a dry burning phenomenon.

In one embodiment, the shape of the coating 24 matches the shape of the flow guide surface 23 and the shape of the relief structure 25. Therefore, the coating 24 does not affect the flow guide surface 23 and the concave-convex structure 25, so that a larger effective heat transfer area is ensured between the water distributed on the coating 24 and the electric heating film 22, and the combination effect of the concave-convex structure 25 and the coating 24 is fully exerted.

In one example, the coating 24 completely covers the flow guide surface 23 and the surface of the concave-convex structure 25. Thus, water can completely cover the flow guide surface 23 and the concave-convex structure 25, and heat generated from various parts of the electric heating film 22 can be more sufficiently absorbed by the water on the coating layer 24.

In one embodiment, the coating 24 is formed on the surfaces of the flow guide surface 23 and the relief structure 25 in a sintered manner.

Thus, the coating 24 is tightly combined with the flow guide surface 23 and the concave-convex structure 25, and the way of forming the coating 24 by sintering is not only easy to realize, but also the coating 24 is uniformly distributed, which is beneficial to uniformly dispersing water on the coating 24 to form a layer of water film.

In one embodiment, the coating 24 includes one or more of an acrylic layer (not shown), a titanium oxide layer (not shown), an organic silicon layer (not shown), or an inorganic silicon layer (not shown).

Thus, the surface of the coating 24 contains more hydrophilic groups such as hydroxyl groups, i.e., has better hydrophilic property, which is beneficial to forming a thicker water film on the coating 24.

In some examples, one or more of an acrylic layer, a titanium oxide layer, an organic silicon layer, or an inorganic silicon layer may be formed on the surfaces of the flow guide surface 23 and the relief structure 25 by sintering. The acrylic layer, the titanium oxide layer, the organic silicon layer, and the inorganic silicon layer each include a hydrophilic group such as a hydroxyl group or a carboxyl group. The acrylic layer refers to a hydrophilic coating layer having hydrophilic properties prepared by using acrylic acid as a functional monomer. For example, acrylic acid may be prepared as a high polymer by homopolymerization or copolymerization, and then the high polymer may be sintered to form an acrylic layer.

It should be noted that the coating 24 may be formed in a manner as appropriate. The coating 24 may comprise only an acrylic layer or only a titanium oxide layer or only a silicone layer or only an inorganic silicone layer. The coating 24 may also include both an acrylic layer and a titanium oxide layer, or both a titanium oxide layer and an organic silicon layer. The coating 24 may also include multiple acrylic layers or multiple titanium oxide layers or multiple silicone layers, etc. That is, the manner of composition of the coating layer 24 may be set as the case may be, i.e., the manner of composition of the coating layer 24 is not limited to the above-listed manner of composition.

In one embodiment, the coating 24 includes a plurality of hydrophilic, nanoscale particles (not shown). Thus, the coating 24 has a relatively high hydrophilic property, which facilitates uniform dispersion of water on the coating 24.

The size of the nano-sized particles is in the range of 1nm to 100 nm. The nanoscale particles may also improve the aging resistance and strength of the coating 24. The nanoscale particles can be oxide particles, for example silica particles.

In some examples, the particles are 20nm, 30nm, 40nm, 60nm, 70nm, or 90nm in size. The size of the particles is not limited to the values listed in the above examples.

Referring to fig. 10, in one embodiment, the concave-convex structure 25a is a layered structure formed on the flow guiding surface 23a, and the concave-convex structure 23 completely covers the flow guiding surface 23 a.

In this way, the coverage area of the textured structure 25a is large, so that water can flow along the textured structure 25a and sufficiently cover the textured structure 25a, which is high in heat transfer efficiency.

In one embodiment, the chamber 10 is composed of a metal material. As such, the chamber 10 is not susceptible to corrosion.

In an embodiment of the present invention, the chamber 10 is formed of food-grade stainless steel material. In this manner, the steam formed in the cavity 10 may directly contact the food to heat the food, so that the steam generator 100 may be applied to daily stuff.

In one embodiment, the electrical heating element 20 includes an insulating element (not shown) disposed at an outermost layer. The insulating element covers an electrical heating film 22, the electrical heating film 22 being located between the insulating element and the substrate 21. In this way, the loss of heat generated by the electric heating element 20 can be reduced.

Referring to fig. 4-6, in one embodiment, the water jet 12 is slit-shaped.

Thus, the water sprayed from the water spray 12 is slit-shaped and has a large water spray area, and thus is easily vaporized into steam. Meanwhile, the contact area between the water sprayed from the slit-shaped water spray nozzles 12 and the concave-convex structure 25 on the flow guide surface 23 is large, and the water can be distributed on the concave-convex structure 25 more uniformly and flow along the concave-convex structure 25.

It is understood that the width of the slit-shaped water discharge opening 12 may be made equal throughout in order to make the water distribution from the water discharge opening 12 more uniform.

In one embodiment, the steam generator 100 includes a water inlet pipe 30. One end of the water inlet pipe 30 is provided with a water inlet 31. The other end of the water inlet pipe 30 penetrates through the first side plate 14 of the cavity 10 and is positioned in the steam generating chamber 11. The other end of the water inlet pipe 30 is provided with a water jet 12. The spout 12 extends along the length of the other end of the inlet pipe 30. The water jet 12 is communicated with the water inlet 31.

In this way, water can enter the inlet pipe 30 directly from the inlet opening 31 and then be sprayed to the flow guide surface 23 from the water spray opening 12. Because the water jet 12 is located in the steam generating chamber 11, the distance between the water jet 12 and the diversion surface 23 is relatively short, so that the water sprayed from the water jet 12 can be relatively fully covered on the concave-convex structure 25 of the diversion surface 23. At the same time, the manner of opening the water inlet pipe 30 to form the water jet 12 is easy to realize, and the manufacturing is facilitated.

It is understood that the water jet 12 may be directly formed on the chamber 10 and have a slit shape.

In one embodiment, spout 12 includes a plurality of jets (not shown). The plurality of nozzles are arranged at intervals.

In this manner, the flow rate of water ejected from each nozzle is small, and thus vaporization is easy. The contact area between the water sprayed from the plurality of nozzles and the diversion surface 23 is large, so that the water sprayed from the water spray 12 can be distributed on the diversion surface 23 more uniformly.

It will be appreciated that the plurality of nozzles are arranged in stripes in order to provide a more uniform distribution of water emitted from the water jets 12.

In one embodiment, the chamber 10 is opened with an air outlet 13 communicating with the steam generating chamber 11. The air outlet 13 is located on the lower side of the water jet 12. The air outlet 13 is closer to the upper end of the chamber 10 than to the lower end of the chamber 10.

In this way, since the air outlet 13 is located closer to the upper end of the chamber 10, the water vaporized in the steam generating chamber 11 can be discharged from the air outlet 13 more timely and sufficiently after flowing upward.

It can be understood that, in order to improve the uniformity of the air outlet 13 and improve the flow rate of the air outlet 13, the number of the air outlets 13 is multiple, and the multiple air outlets 13 are arranged at intervals.

In the present example, the steam generator 100 includes an outlet duct 131. The outlet pipe 131 communicates with the outlet 13.

In one embodiment, the side of the deflector surface 23 adjacent the spout 12 is inclined with respect to the chamber 10 in a direction away from the chamber 10.

Thus, since the side of the guiding surface 23 close to the water spraying opening 12 is inclined towards the direction far away from the cavity 10, the water sprayed from the water spraying opening 12 to the guiding surface 23 can flow downwards along the inclined guiding surface 23 and fully cover the guiding surface 23 and the concave-convex structure 25, so that the heat generated by the electric heating film 22 can be fully absorbed by the water on the guiding surface 23, and the electric heating element 20 can be effectively prevented from generating a dry burning phenomenon.

In one embodiment, the projection of the steam generating chamber 11 on the side 101 of the cavity 10 is a right-angled trapezoid structure. The projection of the flow guide surface 23 on the side surface 101 of the cavity 10 forms a long side waist of the right-angle ladder structure.

In this way, the area of the guide surface 23 is large, so that the electric heating film 22 can sufficiently transfer heat to the water covering the guide surface 23 through the substrate 21, thereby sufficiently heating the water.

In one example, the width of the steam generating chamber 11 (as shown in the X-axis direction of fig. 1) is gradually increased along the length direction of the cavity 10 (as shown in the Y-axis direction of fig. 1). In this way, the volume of the upper space of the steam generating chamber 11 is larger than the volume of the lower space of the steam generating chamber 11, so that the water sprayed from the water spray 12 can be sufficiently vaporized in the upper space of the steam generating chamber 11. At the same time, this prevents the lower space of the steam generating chamber 11 from remaining water.

It is understood that the steam generator 100 has a substantially right-angled trapezoidal structure in order to facilitate the installation and removal of the steam generator 100. The electric heating element 20 has a substantially rectangular parallelepiped shape. The electric heating element 20 is mounted on the chamber 10 and constitutes a sidewall of the chamber 10. The second side plate 15 of the cavity 10 is formed with an outer mounting surface 151. The mounting surface 151 has a fixing interface 152 formed thereon. The steam generator 100 may be mounted to other devices, such as a steam heating device, by the fixing interface 152 being engaged with the first bolt (not shown). In the present example, the first side panel 14 is connected substantially perpendicular to the second side panel 15.

It should be noted that the "upper space" and the "lower space" refer to a position state of the steam generator 100 in a normal use state, for example, a position state as shown in fig. 1.

In the embodiment of the present invention, the substrate 21 is covered with the electric heating film 22. The substrate 21 is covered with the electric heating film 22 means that the area of the substrate 21 is larger than that of the electric heating film 22, and when the electric heating film 22 is disposed on the substrate 21, the substrate 21 is still at a position where the electric heating film 22 is not disposed, as shown in fig. 7, which is advantageous in that when water is sprayed through the water spraying port 12, most of the water flows to a position where the flow guide surface is lower and is heated by the electric heating film 22, thereby ensuring the amount of steam generated.

The substrate 21 may be made of one or more of a stainless steel material, a copper material, an aluminum material, a glass-ceramic material, or a ceramic material.

In one example, the water jets 12 are located at the top of the steam generating chamber 11, with the water jets 12 being closer to the flow guide surface 23 relative to the mounting surface 151. Thus, the distance between the water jet 12 and the diversion surface 23 is short, so that the water sprayed out from the water jet 12 can be ensured to fall on the diversion surface 23 sufficiently.

In the example of fig. 1 and 4, when assembling the steam generator 100, the cavity 10 may be vertically fixed by a first bolt (not shown), in which the mounting surface 151 is parallel to the vertical plane m, then the guiding surface 23 of the base plate 21 faces the cavity 10, and then the electric heating element 20 is obliquely fixed on two opposite first side plates 14 of the cavity 10 at an angle with respect to the mounting surface 151 by a second bolt (not shown), so that the assembly of the steam generator 100 is completed.

It should be noted that, when the electric heating element 20 is fixed on the cavity 10 obliquely relative to the mounting surface 151, an included angle between the flow guiding surface 23 and the mounting surface 151 is an included angle b, that is, an included angle between the flow guiding surface 23 and a vertical plane m as shown in fig. 1. The included angle b may range from greater than 0 degrees to less than 90 degrees. Thus, the water sprayed from the water spray 12 can be ensured to flow uniformly along the diversion surface 23 and fully cover the diversion surface 23.

In some examples, the included angle b is 5 degrees, 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, or the like.

It is understood that in other embodiments, the steam generator 100 may be mounted to other devices, such as a steam heating device, by welding. The chamber 10 may be connected to the electric heating element 20 by means of welding. Therefore, the assembly of the steam generator 100 is not limited to the illustrated assembly.

Referring to fig. 7, 8 and 11, in one embodiment, the electric heating element 20 includes an insulating heat conducting layer 26. The electric heating film 22 includes a resistance circuit 27. The heat conductive layer 26 connects the substrate 21 and the resistance circuit 27. The thermally conductive layer 26 includes a first thermally conductive layer 261 and at least one second thermally conductive layer 262. At least one second thermally conductive layer 262, the resistive circuit 27, and the first thermally conductive layer 261 are stacked in sequence on the substrate 21.

In this way, the plurality of heat conduction layers can not only perform sufficient heat conduction, but also effectively isolate the resistor circuit 27 from the outside, thereby preventing substances such as external ash layers or water from entering the resistor circuit 27 and causing negative effects such as electric leakage on the resistor circuit 27.

Specifically, the thermally conductive layer 26 includes 5 second thermally conductive layers 262. In assembling the electric heating element 20, the 5 second heat conduction layers 262 may be sequentially stacked on the surface 231 of the substrate 21 opposite to the current guiding surface 23, then the resistor circuit 27 is stacked on one of the 5 second heat conduction layers 262 farthest from the substrate 21, and then the first heat conduction layer 261 is stacked on the resistor circuit 27, so that the resistor circuit 27 is sandwiched between the first heat conduction layer 261 and the second heat conduction layer 262 farthest from the substrate 21. The first heat conducting layer 261, the resistance circuit 27 and the 5 second heat conducting layers 262 can be fixed by sintering during the whole assembly process of the electric heating element 20.

In one embodiment, first thermally conductive layer 261 overlays resistive circuit 27 in an orthographic area of resistive circuit 27. In this way, first heat conducting layer 261 is able to substantially prevent external dust or water from directly dripping on resistor circuit 27.

In one embodiment, resistance circuit 27 includes a plurality of sub-resistance circuits 271. The plurality of sub-resistor circuits 271 are provided at intervals. The plurality of sub-resistance circuits 271 are connected in parallel.

Thus, the plurality of sub-resistor circuits 271 do not interfere with each other, the power of each resistor circuit 271 is the same, and the surface power density distribution of each resistor circuit 271 is uniform.

It should be noted that the specific arrangement of the resistor circuit 27 is not limited to the above-mentioned embodiments, and may be correspondingly configured according to specific situations.

In one example, the plurality of sub-resistor circuits 271 are connected to each other via a conductive medium 272.

In some examples, the material of the sub-resistive circuit 271 includes a rare earth oxide material.

Thus, under the condition of the same heat conduction area, the surface heat load of the sub-resistance circuit 271 is large, and the heat conduction efficiency is high.

Preferably, the sub-resistor circuit 271 is composed of microcrystalline glass powder, fine aluminum powder, an inorganic binder phase organic solvent carrier, and a rare earth oxide. Therefore, the resistance circuit has high heat conduction efficiency and good thermal stability.

In an embodiment of the invention, the material of the thermally conductive layer 26 comprises a rare earth oxide material.

In this way, under the condition of the same heat conduction area, the heat conduction layer 26 has a larger surface heat load, and the heat conduction efficiency of the heat conduction layer 26 is higher, so that the heat conduction layer is more energy-saving, and the heat generated by the resistance circuit 27 can be uniformly led out from the heat conduction layer 26 to the substrate 21.

Specifically, the heat conductive layer 26 is made of a rare earth dielectric slurry. The rare earth medium slurry consists of solid phase components and an organic solvent carrier, wherein the solid phase components comprise one or more of silicon dioxide, boron trioxide and rare earth oxide, and the organic solvent carrier comprises terpineol, tributyl citrate and ethyl cellulose.

Thus, the heat conducting layer 26 made of the rare earth medium slurry has moderate strength, high heat conducting efficiency and good thermal stability.

In some examples, the electrical heating element 20 includes an electrode 28. The electrodes 28 are disposed on the thermally conductive layer 26. The electrode 28 is connected to the resistance circuit 27 through a conductive medium (not shown).

In this way, the resistance circuit 27 is connected to the electrode 28 via the conductive medium, and the conductive medium can ensure the stability of the conduction of the resistance circuit 27.

Preferably, the electrode 28 is in the form of a sheet, and the electrode 28 is, for example, a copper sheet. Thus, the electrode 28 has better conductive effect.

The steam heating apparatus of the embodiment of the present invention includes the steam generator 100 according to any one of the above-described embodiments.

In the steam heating device of the embodiment of the invention, the heat-conducting concave-convex structure 25 is formed on the flow-guiding surface 23. The concave-convex structure 25 increases the surface area of the guiding surface 23, so that when the water sprayed from the water spraying opening 12 to the guiding surface 23 flows along the concave-convex structure 25 on the guiding surface 23, the concave-convex structure 25 can increase the effective area of the electric heating film 22 for heat transfer with the water, thereby increasing the steam generation efficiency of the steam generator 100.

In one example, the steam heating device is a steam oven, i.e., cooking can be performed using steam.

In one embodiment, the steam heating device comprises an inner container (not shown). The inner container is formed with a heating chamber (not shown) for placing food to be heated. The heating chamber is communicated with the steam generating chamber 11. In this manner, steam generated by the steam generator 100 may enter the heating chamber to heat the food to be heated.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

In the description of the present specification, reference to the description of the terms "one embodiment", "some embodiments", "an illustrative embodiment", "an example", "a specific example", or "some examples", etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A steam generator, comprising:

the steam generator comprises a water spraying port positioned at the upper end of the cavity, and the water spraying port is communicated with the steam generating chamber;

the electric heating element is arranged on the cavity and comprises a heat-conducting substrate and an electric heating film, the electric heating film is fixed on one side of the substrate, the substrate separates the electric heating film and the steam generating chamber, the substrate comprises a flow guide surface positioned in the steam generating chamber, the water spray opening faces the flow guide surface, and a heat-conducting concave-convex structure is formed on the flow guide surface;

the projection of the steam generating chamber on the side surface of the cavity is of a right-angled trapezoid structure, and the projection of the flow guide surface on the side surface of the cavity forms the long side waist of the right-angled trapezoid structure;

the width of the steam generating chamber is gradually increased along the length direction of the cavity, and the volume of the upper space of the steam generating chamber is larger than that of the lower space of the steam generating chamber, so that the water sprayed from the water spray opening can be fully vaporized in the upper space of the steam generating chamber.

2. The steam generator of claim 1, wherein the relief structure is a layered structure formed on the flow guide surface, the relief structure completely covering the flow guide surface.

3. The steam generator of claim 1, wherein the concave-convex structure comprises a plurality of water storage grooves recessed relative to the flow guiding surface, and the plurality of water storage grooves are spaced apart from each other.

4. The steam generator of claim 1, wherein the flow guide surface is formed by a surface modification process to form the relief structure.

5. The steam generator of claim 1, wherein the electrical heating element comprises a thermally conductive, hydrophilic coating covering the flow-directing surface and the surface of the relief structure.

6. The steam generator of claim 5, wherein the coating has a shape that matches a shape of the flow guide surface and a shape of the relief structure.

7. The steam generator of claim 1, wherein the water jets are slit-shaped.

8. The steam generator of claim 1, wherein the water jet comprises a plurality of jets, the plurality of jets being spaced apart.

9. The steam generator of claim 1, wherein a side of the flow deflector surface proximate the water jet is angled away from the cavity relative to the cavity.

10. The steam generator of claim 1, wherein the electrical heating element comprises an insulated thermally conductive layer, the electrical heating film comprises an electrical resistance circuit, the thermally conductive layer connects the substrate and the electrical resistance circuit, the thermally conductive layer comprises a first thermally conductive layer and at least one second thermally conductive layer, the electrical resistance circuit, and the first thermally conductive layer are stacked in sequence on the substrate.

11. The steam generator of claim 10, wherein the resistive circuit comprises a plurality of sub-resistive circuits spaced apart and connected in parallel.

12. A steam heating device, characterized by comprising a steam generator according to any of claims 1-11.