Heater Plate Assembly

Abstract

The heater plate assembly is an integral assembly of a plate with which an object to be heated comes into contact and a film heater that generates heat when electricity is applied, and includes a plate (20), a film heater (33), two insulating sheets (32, 34), a power supply connection portion (40), a heater holder (50), and a plate cover (60). The plate is made of a thermally conductive metal and has a heating surface (21) with which an object to be heated comes into contact, and an assembly surface (24). The heater holder is made of a thermally conductive metal and covers the film heater on the side opposite the plate to the film heater. The heater holder holds the film heater between a holding surface (51) and the assembly surface of the plate via an insulating sheet, and radiates heat from a radiation surface (53). The plate cover is made of metal and covers the heater holder on the side opposite the plate to the heater holder. The plate cover forms an air chamber (66) between the reflective surface (65) and the radiating surface of the heater holder.

Description

[Technical field]

[0001] The present disclosure relates to a heater plate assembly. [Background technology]

[0002] Conventionally, heater plate assemblies used as cooking hot plates and the like are known. For example, the cooking hot plates disclosed in Patent Documents 1 and 2 include a cooking plate body having a surface plate on the upper surface. The cooking plate body includes a film heater that generates heat when electricity is applied to the lower surface side of the surface plate, and a back plate disposed on the lower surface side of the film heater. The back plate reflects radiant heat from the film heater.

[0003] The film heater, which has insulating sheets arranged on both sides, is sandwiched between a front plate and a back plate together with a pressure plate for adjusting the thickness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Utility Model Registration No. 3232687 [Patent Document 2] Utility Model Registration No. 3233768 Summary of the Invention

[0005] The cooking hot plates of Patent Documents 1 and 2 have no space between the film heater and the surface plate, so they can reduce heat loss caused by heating a large space, compared to hot plates that use a sheath heater to heat a large space. In addition, because heat is generated widely and uniformly on the back of the surface plate, temperature variations on the heating surface of the surface plate are suppressed.

[0006] However, in the conventional technologies of Patent Documents 1 and 2, the back plate holding the film heater is directly exposed to the outside, so heat flows out from the back plate to the outside. Therefore, there is room for improvement in the thermal efficiency of heating the front plate with the heat generated by the film heater.

[0007] It is an object of the present disclosure to provide a heater plate assembly that improves thermal efficiency.

[0008] The heater plate assembly according to the present disclosure is an integral assembly of a plate that comes into contact with an object to be heated and a film heater that generates heat when electricity is applied. The heater plate assembly includes a plate, a film heater, two insulating sheets, a power supply connection section, a heater holder, and a plate cover.

[0009] The plate is made of a thermally conductive metal and has a heating surface that comes into contact with an object to be heated and an assembly surface behind the heating surface. The plate of the present disclosure corresponds to the “front plate” of Patent Documents 1 and 2.

[0010] The film heater is placed on the mounting surface of the plate. Two insulating sheets sandwich the film heater to insulate both sides of the film heater. The power supply connector is used to connect the power supply to the film heater.

[0011] The heater holder is made of a thermally conductive metal and covers the film heater on the side opposite the plate. The heater holder holds the film heater with an insulating sheet between a holding surface on the film heater side and an assembly surface of the plate, and radiates heat from a radiation surface on the side opposite the holding surface.

[0012] The plate cover is made of metal and covers the heater holder on the opposite side of the heater holder from the plate. The plate cover has a reflective surface facing the radiation surface of the heater holder, and forms an air chamber between the reflective surface and the radiation surface of the heater holder.

[0013] In the heater plate assembly of the present disclosure, an air chamber is formed between the "rear plate" of Patent Documents 1 and 2 by a double structure of a heater holder and a plate cover. The radiation surface of the heater holder is not directly exposed to the outside, and the air layer inside the air chamber functions as a heat insulating layer. In addition, the reflective surface of the plate cover reflects the radiant heat, so the heat can be efficiently transferred to the plate side. Therefore, the thermal efficiency of heating the plate by the heat generated by the film heater is improved.

[0014] Preferably, the thickness of the plate is greater than the thickness of the heater holder, so that the heat generated by the film heater is transferred more to the plate, which has a relatively large heat capacity, thereby improving the thermal efficiency of heating the plate. [Brief description of the drawings]

[0015] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: [Figure 1] FIG. 1 is a diagram of a cooking device in which a heater plate assembly of one embodiment is used; [Diagram 2] FIG. 2 is a plan view of a heater plate assembly of one embodiment; [Diagram 3] FIG. 3 is a bottom view of a heater plate assembly of one embodiment; [Figure 4] FIG. 4 is a perspective view of a heater plate assembly according to one embodiment, seen from the bottom side; [Diagram 5] FIG. 5 is a front view of a heater plate assembly of one embodiment; [Figure 6] FIG. 6 is a schematic exploded view of a heater plate assembly according to one embodiment; [Figure 7] FIG. 7 is a schematic cross-sectional view of a heater plate assembly according to one embodiment; [Figure 8] FIG. 8 is an enlarged view of part VIII of FIG. 7; [Figure 9] FIG. 9 is a schematic cross-sectional view of a heater plate assembly of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] (One embodiment) A heater plate assembly according to one embodiment will be described with reference to the drawings. The heater plate assembly is a heater that transfers heat to an object to be heated that is in contact with the plate, and is configured by integrating a plate and a film heater that generates heat when electricity is applied. For example, the heater plate assembly of this embodiment is used in a cooking device that heats and cooks food, which is an object to be heated.

[0017] An example of a cooking device 90 is shown in Fig. 1. This cooking device 90 heats an object to be heated, such as bread, from both the top and bottom by sandwiching it between a base 91 and a cover 93 supported by a bottom case 92. The cover 93 rotates about a hinge portion 98 as a fulcrum and can be opened and closed relative to the base 91. A heater plate assembly 100 is attached to the top surface of the base 91 and the bottom surface of the cover 93.

[0018] When attached to the cooking appliance 90, among the components of the heater plate assembly 100, the heating surface 21 of the plate 20 is exposed to the outside, and the other elements are hidden behind the plate 20. In this example, the heater plate assembly 100 on the base 91 side can be removed by simply lifting it up. The heater plate assembly 100 on the cover 93 side can be removed by releasing the engagement of the plate claws 28. The user can remove the heater plate assembly 100 and wash it with water.

[0019] The configuration of a heater plate assembly 100 according to one embodiment will be described with reference to Figs. 2 to 8. External views are shown in Figs. 2 to 5. Figs. 2 and 3 correspond to views taken in the directions of arrows II and III in Fig. 4, respectively, and Fig. 5 corresponds to a view taken in the direction of arrow V in Fig. 3. Fig. 6 shows a schematic exploded view. Fig. 7 shows a schematic cross-sectional view of one side relative to the central axis O, and Fig. 8 shows an enlarged view of part VIII in Fig. 7. In the schematic exploded views and schematic cross-sectional views, the thickness dimensions of particularly thin components are exaggerated.

[0020] First, the external structure will be described with reference to Figures 2 to 5. The heater plate assembly 100 of this embodiment has a generally rectangular plate shape having long sides corresponding to the front-rear direction of the cooking device 90 and short sides corresponding to the left-right direction of the cooking device 90. The heating surface 21 of the plate 20 is exposed on one side, and the cover back surface 61 of the plate cover 60 is exposed on the other side.

[0021] A plate flange 22 is formed on the outer periphery of the plate 20, surrounding the heating surface 21. Plate claws 28 are provided on each short side of the plate 20. The plate cover 60 has a height of about several mm from the joint surface with the plate 20. This height ensures an internal air chamber 66 (see FIG. 7), which will be described later. Circular and arc-shaped reinforcing ribs 63 are formed on the back surface 61 of the cover. In addition, a check valve 68 for releasing the internal pressure of the air chamber 66 is provided in one corner of the plate cover 60.

[0022] A power supply connection part 40 for connecting a power supply to the film heater 33 (see Figs. 6 and 7) is provided inside the cover insertion hole 64 of the plate cover 60. A tubular housing part 41 of the power supply connection part 40 is formed of an insulating material such as resin. The power supply connection part 40 of this embodiment has a cylindrical tubular housing part 41 in the center of the plate cover 60, and is provided with a plurality of terminals 45 for power supply and temperature detection.

[0023] Next, the internal structure of the heater plate assembly 100 will be described with reference to Figs. 6 to 8. Assuming an assembly process of the heater plate assembly 100, the heater plate assembly 100 is illustrated in a position with the cover back surface 61 facing up and the heating surface 21 facing down. In the following description, up and down are represented according to the illustrated direction of Figs. 6 to 8. In Fig. 6, the heater plate assembly 100 is configured by assembling the plate 20, the plate side insulating sheet 32, the film heater 33, the holder side insulating sheet 34, the power connection part 40, the waterproof ring 70, the heater holder 50, and the plate cover 60 in that order from the bottom. The power connection part 40 and the waterproof ring 70 may be first assembled to the heater holder 50 to form a subassembly.

[0024] The plate 20 is made of a thermally conductive metal and has a heating surface 21 with which the object to be heated comes into contact, and an assembly surface 24 which is the back surface of the heating surface 21. In this embodiment, aluminum is used as the material for the plate 20 because of its thermal conductivity, weldability and light weight. A film heater 33 and two insulating sheets 32, 34 are arranged on top of each other on the assembly surface 24 side of the plate 20. As shown by the dashed lines in Figures 2 and 3, the rectangular shapes of the film heater 33 and the insulating sheets 32, 34 are the same size.

[0025] The film heater 33 is a thin-film heater with a zigzag conductive path formed therein, and is also called a circuit heater. The film heater 33 has less heat loss than a sheathed heater that heats a wide surrounding space, and can uniformly heat the entire heating surface 21 of the plate 20. Two insulating sheets 32 and 34 are provided on either side of the film heater 33 to insulate both sides of the film heater 33.

[0026] The power supply connection part 40 is placed on the holder-side insulating sheet 34 and has a housing tube part 41 formed of an insulating material. An outer peripheral wall 43 of the housing tube part 41 is inserted into the holder insertion hole 54 of the heater holder 50 and the cover insertion hole 64 of the plate cover 60. A flange part 42 protruding radially outward is provided at the end of the housing tube part 41 facing the holder-side insulating sheet 34. A terminal seat 44 on which a plurality of terminals 45 are erected is formed on the inside of the housing tube part 41. In this embodiment, four terminals 45 are provided: two power supply terminals and two temperature detection terminals.

[0027] 8, the insulating sheets 32 and 34 are formed with escape holes for electrically connecting the power supply connection portion 40 and the film heater 33. For example, at the location of the escape hole, a temperature sensor 48 such as an NTC thermistor biased by a spring 47 is pressed against the temperature detection portion of the film heater 33.

[0028] Next, before describing the waterproof ring 70, the heater holder 50 and the plate cover 60 will be described. The heater holder 50 is made of a thermally conductive metal, and covers the film heater 33 on the side opposite the plate 20 (the upper side in the figure) with respect to the film heater 33. In this embodiment, like the plate 20, aluminum is used as the material for the heater holder 50 because of its thermal conductivity, weldability, and light weight.

[0029] The surface of heater holder 50 facing film heater 33 (lower side in the figure) is called holding surface 51, and the surface opposite holding surface 51 (upper side in the figure) is called radiation surface 53. Heater holder 50 holds film heater 33 between holding surface 51 and mounting surface 24 of plate 20 via insulating sheets 32, 34. More specifically, holes for preventing misalignment are formed in film heater 33 and insulating sheets 32, 34, and projections for preventing misalignment that correspond to the holes are formed in holding surface 51 of heater holder 50.

[0030] The heater holder 50 has a holder flange 52 located outside the outer periphery of the film heater 33 and the insulating sheets 32, 34. The holder flange 52 is formed so as to bend in a step from the holding surface 51 toward the plate 20. The height of the step corresponds to the thickness of the film heater 33 and the insulating sheets 32, 34 stacked together. The holder flange 52 is welded to the inner frame region 25 on the mounting surface 24 of the plate 20. By welding the holder flange 52 to the plate 20, the film heater 33 and the insulating sheets 32, 34 are fixed integrally with the plate 20 and the heater holder 50. A holder insertion hole 54 is formed in the center of the heater holder 50, through which the power supply connection part 40 can be inserted.

[0031] When the film heater 33 generates heat by energizing the terminal 45 of the power connection part 40, the heat is transferred to both the plate 20 and the heater holder 50. Here, the plate 20 is thicker than the heater holder 50. Therefore, more of the heat generated by the film heater is transferred to the plate, which has a relatively large heat capacity. The heat transferred to the heater holder 50 is radiated from the radiation surface 53 towards the plate cover 60.

[0032] The plate cover 60 is made of metal and covers the heater holder 50 on the side opposite the plate 20 (upper side in the figure) of the heater holder 50. In this embodiment, aluminum is used as the material for the plate cover 60 because of its radiant heat reflectivity, weldability, and light weight. Alternatively, SUS304, which is used for the back plate in the conventional techniques of Patent Documents 1 and 2, may be used because of its radiant heat reflectivity, although it is less lightweight than aluminum.

[0033] The surface of the plate cover 60 facing the radiation surface 53 of the heater holder 50 is called the reflective surface 65, and the exposed surface on the opposite side to the reflective surface 65 (upper side in the figure) is called the cover back surface 61. The reflective surface 65 reflects radiant heat from the radiation surface 53 of the heater holder 50 toward the heater holder 50, and suppresses the outflow of heat from the cover back surface 61 to the outside. The plate cover 60 forms an air chamber 66 between the reflective surface 65 and the radiation surface 53 of the heater holder 50. The air inside the air chamber 66 has a lower thermal conductivity than metal, and therefore functions as a heat insulating layer.

[0034] When the air inside the air chamber 66 expands due to a rise in temperature, the internal pressure rises. Reinforcement ribs 63 formed on the cover rear surface 61 prevent deformation of the cover rear surface 61. Also, a check valve 68 having a vent function that opens when the internal pressure of the air chamber 66 rises and releases the internal pressure to the outside is provided at one corner of the plate cover 60. The check valve 68 is made of an elastic material such as rubber, and is attached to a check valve attachment hole 67 formed in the plate cover 60.

[0035] When the pressure difference between the internal pressure and the external pressure is equal to or less than a predetermined value, the umbrella part of the check valve 68 is in contact with the cover back surface 61 due to elastic force. When the pressure difference between the internal pressure and the external pressure exceeds a predetermined value, the umbrella part of the check valve 68 is pushed up by the force of the air flow passing through the gap between the check valve mounting hole 67 and the check valve 68, and air flows out to the outside. Note that, as will be described later, there is a possibility that water may enter the air chamber 66, in which case the steam generated by heating the water will be released to the outside through the open check valve 68.

[0036] The plate cover 60 has a cover flange 62 located outside the outer periphery of the heater holder 50. The cover flange 62 is formed so as to bend in a step from the reflecting surface 65 toward the plate 20. The height of the step is approximately the height of the air chamber 66. The cover flange 62 is welded to the outer frame region 26 located outside the inner frame region 25 to which the holder flange 52 is welded, on the mounting surface 24 of the plate 20. Also, a cover insertion hole 64 is formed in the center of the plate cover 60, through which the power connection part 40 can be inserted.

[0037] The waterproof ring 70 is formed of, for example, silicone rubber, and is provided along the outer peripheral wall 43 of the tubular housing portion 41. The lower end of the waterproof ring 70 faces the flange portion 42 of the tubular housing portion 41. The waterproof ring 70 prevents water from entering through gaps between the outer peripheral wall 43 of the tubular housing portion 41 and the holder insertion hole 54 and the cover insertion hole 64. A protrusion (not shown) is formed on the inner peripheral wall of the waterproof ring 70 to increase the contact surface pressure with the outer peripheral wall 43 of the tubular housing portion 41. Since the heater plate assembly 100 is washed with water, waterproof performance is required to prevent short circuits and corrosion of electrical components in particular.

[0038] A fitting groove 75 into which the inner peripheral edge 55 of the holder insertion hole 54 of the heater holder 50 fits is formed in the middle of the outer peripheral wall of the waterproof ring 70 in the height direction. The bottom and upper and lower walls of the fitting groove 75 abut against the inner peripheral edge 55 from three sides, ensuring high waterproofing performance against water intrusion into the area housing the electrical components.

[0039] The inner peripheral wall of the cover insertion hole 64, which is bent so as to extend in the axial direction, abuts against the outer peripheral wall of the upper end of the waterproof ring 70. Even if water infiltrates into the air chamber 66 from the gap between the waterproof ring 70 and the cover insertion hole 64, it will not directly affect the electrical components, so a high level of waterproofing is not required compared to the gap with the holder insertion hole 54. However, there is a possibility that the moisture that has infiltrated into the air chamber 66 will be heated and generated steam will increase the internal pressure of the air chamber 66. Therefore, as described above, the plate cover 60 is provided with a check valve 68.

[0040] (Comparison with Comparative Example) As a comparative example for comparison with this embodiment, Fig. 9 shows a schematic cross-sectional view of a heater plate assembly 110 corresponding to the prior art of Patent Documents 1 and 2. In the heater plate assembly 110 of the comparative example, an upper insulating sheet 13, a film heater 14, and a lower insulating sheet 15 are overlappingly held between a front plate 11 and a back plate 17. The back plate 17 is fastened to a joining protrusion of the front plate 11 by a screw 19. A waterproof packing 12 is provided on the outer edge between the front plate 11 and the back plate 17 and on the seat of the screw 19.

[0041] In the heater plate assembly 110 of the comparative example, when the film heater 14 generates heat, the heat is transferred to both the front plate 11 and the back plate 17, as indicated by the block arrows. Because the back plate 17 is directly exposed to the outside, heat flows out from the back plate 17 to the outside. Therefore, of the total amount of heat generated by the film heater 14, the proportion of the amount of heat that is not used to heat the front plate 11 is relatively large, and there is room for improvement in thermal efficiency.

[0042] In addition, the number of parts is large because the back plate 17 and the front plate 11 are fastened with multiple screws 19, and the labor required increases. A thick metal wall is required to provide the connecting protrusions on the front plate 11, which increases the weight. Furthermore, the waterproof performance is difficult to stabilize due to variations in the work of assembling the waterproof packing 12 between the back plate 17 and the front plate 11.

[0043] In contrast, in the heater plate assembly 100 of this embodiment, an air chamber 66 is formed between the back plate 17 of the comparative example by a double structure of the heater holder 50 and the plate cover 60. The radiation surface 53 of the heater holder 50 is not directly exposed to the outside, and the air layer inside the air chamber 66 functions as a heat insulating layer. In addition, the reflective surface 65 of the plate cover 60 reflects the radiant heat, so the amount of heat can be efficiently transferred to the plate 20 side. Therefore, the thermal efficiency of heating the plate 20 by the heat generated by the film heater 33 is improved.

[0044] Also, the heater holder 50 and the plate cover 60 are welded to the plate 20 without using screws 19, thereby reducing the number of parts. Furthermore, since no connecting protrusions for fixing with screws are required and the plate 20 and the heater holder 50 are made of aluminum, the weight can be reduced. In addition, since the heater holder 50 and the plate cover 60 are welded to the inner frame region 25 and the outer frame region 26 on the mounting surface 24 of the plate 20, waterproofing is improved by sealing with a double frame.

[0045] (Other embodiments) (a) The heater plate assembly of the present disclosure is not limited to use as a cooking device for cooking food, but may be used as a heater for any purpose in which heat is transferred to an object to be heated in contact with the plate, such as for handicrafts, arts and crafts, or medical purposes.

[0046] (b) The plate 20 and the heater holder 50 may be made of a heat conductive metal other than aluminum. The plate cover 60 may be made of a metal that reflects radiant heat other than aluminum or SUS304. When welding the flanges 52, 62 to the mounting surface 24 of the plate 20 as in the above embodiment, good weldability is also a requirement. However, one or both of the heater holder 50 and the plate cover 60 may be joined to the plate 20 by a method other than welding, such as by screwing. In that case, the heater holder 50 or the plate cover 60 may be made of a metal that has poor weldability.

[0047] (c) In the above embodiment, the power supply connection unit 40 having the cylindrical housing tube portion 41 is provided in the center of the plate cover 60, but the housing shape and arrangement of the power supply connection unit are not limited to this. For example, a power supply connection unit having a rectangular prism-shaped housing may be provided on one edge of the plate cover. In addition, the shape of the waterproof ring and the structure of the check valve are not limited to those in the above embodiment, and shapes and structures having the desired waterproof function and vent function can be appropriately selected.

[0048] (d) Of the multiple terminals 45 of the power connection unit 40, the terminal for power supply is essential, but the terminal for temperature detection is not necessary when a sensorless method is adopted. In the sensorless method, the temperature is estimated by calculating the resistance from the current value based on the resistance-temperature characteristics of the film heater 33.

[0049] As described above, the present disclosure is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the present disclosure.

[0050] The present disclosure has been described based on the embodiment. However, the present disclosure is not limited to the embodiment and structure. The present disclosure also includes various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one, or less than one, are also within the scope and spirit of the present disclosure.

Claims

1. A heater plate assembly in which a plate that comes into contact with an object to be heated and a film heater that generates heat when electricity is applied are integrally formed, A plate (20) made of a thermally conductive metal and having a heating surface (21) with which an object to be heated comes into contact and an assembly surface (24) which is the back surface of the heating surface; a film heater (33) disposed on the mounting surface side of the plate; two insulating sheets (32, 34) disposed on either side of the film heater to insulate both sides of the film heater; A power supply connection portion (40) to which a power supply is connected to the film heater; a heater holder (50) formed of a thermally conductive metal, covering the film heater on the side opposite the plate, holding the film heater between a holding surface (51) on the film heater side and the mounting surface of the plate via the insulating sheet, and radiating heat from a radiation surface (53) on the side opposite the holding surface; a plate cover (60) made of metal, covering the heater holder on the side opposite to the plate with respect to the heater holder, having a reflective surface (65) facing the radiation surface of the heater holder, and forming an air chamber (66) between the reflective surface and the radiation surface of the heater holder; A heater plate assembly comprising:

2. The heater plate assembly according to claim 1 , wherein the plate has a thickness greater than a thickness of the heater holder.

3. 3. The heater plate assembly according to claim 1, wherein the heater holder has a holder flange portion (52) positioned outside the outer periphery of the film heater and the insulating sheet, and the holder flange portion is welded to the mounting surface of the plate.

4. 4. The heater plate assembly of claim 3, wherein the plate cover has a cover flange portion (62) located outside the outer periphery of the heater holder, and the cover flange portion is welded to an outer frame region (26) located outside an inner frame region (25) to which the holder flange portion is welded on the assembly surface of the plate.

5. the power supply connection portion is made of an insulating material and has a housing tube portion (41) that is inserted into a holder insertion hole (54) of the heater holder and a cover insertion hole (64) of the plate cover; 3. A heater plate assembly as described in claim 1 or 2, wherein a waterproof ring (70) is provided along the outer peripheral wall (43) of the cylindrical housing portion to prevent water from entering through the gap between the holder insertion hole and the cover insertion hole.

6. 3. The heater plate assembly according to claim 1, wherein said plate cover is provided with a check valve (68) that opens when the internal pressure of said air chamber increases to release the internal pressure to the outside.