Heating apparatus

Abstract

To provide a heating apparatus that heats an inner container housing an object to be heated which is in a liquid bath state by heat medium liquid in an inner space of a heating tank or the object to be heated itself via the heat medium liquid to a predetermined temperature while making temperature distribution in the object to be heated uniform, and can maintain the temperature.SOLUTION: An inner container 30 is supported by protrusions 15 protruded from a bottom 11 of a heating tank 10; heat medium liquid is allowed to flow through a gap generated between the bottom 11 of the heating tank 10 and a bottom face of the inner container 30; heat medium liquid heated by a heating part 40 transmits heat to the inner container 30 from a contact area between the heat medium liquid and the inner container 30 on the bottom face and the side face of the inner container 30, by which convection of the heat medium liquid is generated below the inner container 30 in a floating state separate from the bottom 11 of the heating tank 10; temperature of the heat medium liquid can easily rises; and an object to be heated can be appropriately heated.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a heating device for heating an object to be heated using a water bath, and more particularly to a heating device suitable for manufacturing fermented foods that require heating fermentation such as yogurt.

Background Art

[0002] A household yogurt manufacturing device for manufacturing yogurt (fermented milk) at home has a configuration in which a container containing raw milk as a raw material and a starter containing lactic acid bacteria and the like is stored in a predetermined storage space, and this container can be heated and kept warm by a predetermined heating unit. In such a manufacturing device, the container is warmed by the heating unit to keep the raw materials in the container at a constant temperature at which fermentation proceeds, and the raw materials are fermented in the container to obtain yogurt. As an example of such a conventional yogurt manufacturing device, there is one disclosed in Japanese Patent Laid-Open No. 4-271747.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A conventional yogurt manufacturing device has a configuration shown in the above patent document, and includes a heat preservation container for keeping warm milk in a milk pack added with a starter, a thermoelectric element as a heating unit for heating this heat preservation container, temperature control means for controlling the temperature of the heat preservation container, and control means for controlling the heating time.

[0005] In this device, a milk pack is used as a container for yogurt production. After adding and stirring commercially available plain yogurt or the like as a starter to the milk (raw milk) in the milk pack, the milk pack is placed in a heat-insulating container. The heat-insulating container is heated to a predetermined temperature by a thermoelectric element provided on the bottom side of the heat-insulating container. When a preset heating time elapses, assuming that the milk in the milk pack has changed to yogurt by fermentation, the thermoelectric element switches to a cooling state, and the yogurt in the milk pack is cooled.

[0006] In the conventional yogurt manufacturing apparatus, the heating part is located below the heat-insulating container that is the object to be heated, transfers heat to the bottom surface of the heat-insulating container, and further transfers heat from the heat-insulating container to the milk pack inside it. For this reason, a temperature difference occurs for each part in the heat-insulating container located closest to the milk pack, making it difficult for heat to be evenly transferred from the heat-insulating container to the milk pack, resulting in a non-uniform temperature of the milk in the milk pack from top to bottom and making it difficult for fermentation to proceed appropriately.

[0007] The disclosure of the present invention was made to solve the above problems, and an object is to provide a heating device that heats an inner container containing an object to be heated or the object to be heated itself, which is in a liquid bath state by a heat transfer medium liquid in the tank space of a heating tank, via the heat transfer medium liquid, so as to make the temperature distribution in the object to be heated uniform, raise it to a predetermined temperature, and maintain the temperature.

Means for Solving the Problems

[0008] The heating device according to the disclosure of the present invention includes an inner container capable of accommodating a predetermined object to be heated, a heating tank capable of accommodating the inner container and a predetermined heat transfer medium liquid in a tank space, and a heating part capable of heating the heat transfer medium liquid accommodated in the tank space of the heating tank. A plurality of protrusions protruding into the tank space are formed on the bottom of the heating tank, and at least a part of the plurality of protrusions contacts the lower surface of the inner container accommodated in the heating tank to support the inner container, allowing the heat transfer medium liquid to flow between the bottom of the heating tank and the lower surface of the inner container, and the heat transfer medium liquid has a predetermined storage capacity that enables it to contact the side surface of the inner container in the tank space of the heating tank.

[0009] According to the disclosure of the present invention as described above, the inner container is supported by the protrusions protruding from the bottom of the heating tank, and the heat transfer medium liquid can flow through the gap corresponding to the height of the protrusions formed between the bottom of the heating tank and the lower surface of the inner container. The heat transfer medium liquid heated by the heating unit transfers heat to the inner container from the contact portions between the heat transfer medium liquid and the inner container on the lower surface and the side surface of the inner container, so that convection of the heat transfer medium liquid occurs even below the inner container floating away from the bottom of the heating tank, the temperature of the heat transfer medium liquid is likely to rise, and the object to be heated can be uniformly heated through the inner container.

Brief Description of the Drawings

[0010]

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Mode for Carrying Out the Invention

[0011] (First Embodiment of the Present Invention) Hereinafter, the heating device according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 15. In this embodiment, an example of a device applicable to the case of manufacturing yogurt by maintaining a container 30 placed in the tank space of a heating tank at a predetermined temperature through water as a heat transfer medium and fermenting a yogurt raw material as an object to be heated inside the container will be described.

[0012] In each of the above figures, a heating device 1 according to this embodiment includes a heating tank 10 capable of accommodating water 80 as a heat transfer medium in a tank space 10a, a lid portion 20 capable of covering and closing the upper opening of the heating tank 10, a container 30 capable of accommodating an object to be heated 90 inside and accommodated in the tank space 10a of the heating tank 10 together with water 80, a heating portion 40 capable of heating the water 80 accommodated in the tank space 10a of the heating tank 10, temperature sensors 51 and 52 for detecting the temperature of the water 80 accommodated in the tank space 10a of the heating tank 10 and the temperature of the atmosphere around the heating device, and a control portion 60 for controlling the heating portion 40 based on the temperatures detected by these temperature sensors 51 and 52.

[0013] The heating tank 10 is formed in a box shape with an open upper surface that is substantially rectangular in plan view, and has a bottom 11 located below the tank space 10a, an inner wall portion 12 surrounding the tank space 10a from the side, and an outer wall portion 13 located further outside this inner wall portion 12.

[0014] This heating tank 10 is capable of accommodating the container 30 and water 80 as a heat transfer medium in its tank space 10a. Among these, a predetermined amount of water 80 that can come into contact with the side surface of the container 30 in the tank space 10a of the heating tank 10 will be accommodated.

[0015] The heating tank 10 is configured such that a plurality of protrusions 15 protruding into the tank space 10a are provided on the bottom 11. And a plate-shaped heating portion 40 is provided below the bottom 11, and with this heating portion 40, the water 80 and the container 30 on the side of the tank space 10a are heated from the bottom 11 side of the heating tank 10.

[0016] The heating tank 10 has a structure in which the bottom 11, the inner wall portion 12, and the outer wall portion 13 are continuously integrated without gaps. Starting from the portion facing the inner space 10a of the heating tank 10, there are no joints between components on the surface portion where water may splash from above, and it is a mechanism that makes it difficult for water to penetrate into the interior. A lower lid 14 that covers the bottom 11 and the heating unit 40 from below is attached to the lower part of the heating tank 10. The gap between the bottom 11, the inner wall portion 12, and the outer wall portion 13, which are integrally formed with the lower lid 14 on the upper side, and the lower lid 14 forms a closed space isolated from the outside.

[0017] At the upper edge portion that surrounds the upper opening of the heating tank 10, which also serves as the upper end portions of the inner wall portion 12 and the outer wall portion 13 of the heating tank 10, a lid portion 20 described later can be placed. Among this upper edge portion, at the portion corresponding to a predetermined corner of the heating tank 10, a concave portion is provided as a drainage portion 10b to facilitate the outflow of water from the inner space 10a of the tank when the heating tank 10 is tilted for drainage.

[0018] An inclined guide portion 10c in the shape of an inclined surface that descends toward the inner space 10a side is provided from the upper edge portion to the inner wall portion 12 at each corner of the heating tank 10, including the corner with this drainage portion 10b. The guide portion 10c encourages water to flow toward the inner wall portion 12 side when water derived from water droplets adhering to the inside of the lid portion 20 due to condensation flows down from the lid portion side. By allowing the water generated by condensation to flow down into the inner space 10a of the tank through the guide portion 10c and the inner wall portion 12, it is a mechanism that prevents water from leaking outside the heating tank 10. Note that such guide portions are not limited to the corners of the heating tank 10 and may be provided over the entire circumference of the heating tank 10.

[0019] A predetermined vibrator may be provided on the lower side of the bottom 11 of the heating tank 10 together with the heating unit 40 so that the vibration of the vibrator is transmitted to the inner space 10a side, enabling stirring inside the inner container 30 by vibration and stirring of the water 80 placed in the inner space 10a. By stirring by vibration, the temperature of the water 80 and the object to be heated 90 inside the inner container 30 can be made more uniform.

[0020] The heating tank 10 is provided with a placement space for the circuit board forming the control unit 60 in a part of the gap between the inner wall portion 12 and the outer wall portion 13. The circuit board of the control unit 60 is inserted and fixed from the bottom side (downward) into the placement space in a state of being attached to the fixing holder 19. By thus providing the substrate of the control unit 60 in the placement space of the heating tank 10 via the holder 19, it can be easily installed.

[0021] The holder 19 is provided with a plate-shaped buffer material. By positioning the buffer material between the holder 19 and the heating tank 10 in the placement space of the heating tank 10, it is possible to prevent the holder 19 and the control unit 60 from moving inadvertently.

[0022] The control unit 60 that fits into the placement space is provided, as an operation circuit, with a touch sensor type operation switch provided on the surface facing the outer wall portion 13 of the substrate and operable even when covered by the outer wall portion 13. By using the operation switch as a touch sensor type, it is not necessary to expose the switch to the outside, so that the waterproof state of the heating tank 10 can be maintained, the surface of the outer wall portion 13 of the heating tank 10 can be maintained in a flat state, and cleaning by wiping this part can be easily performed. Also, by arranging the operation part on the side surface of the heating tank while ensuring the waterproof performance in this way, the operability is also excellent.

[0023] The circuit board of the control unit 60 is provided with a display circuit, and displays of each setting (temperature, timer, mode (by application)) and the device state (operating, operation completed, remaining time, (when a secondary battery is built-in) charging, battery remaining amount)) are performed. These displays can be visually recognized through the outer wall portion 13 of the heating tank 10 having light transmissivity, and the waterproof state of the heating tank 10 can be maintained in the same way as the operation part.

[0024] Also, a substrate with a USB terminal 16 for power connection is built in at the lower part of the outer wall portion 13 at one end in the longitudinal direction of the heating tank 10, and the USB terminal 16 is arranged to be exposed to the outside from the outer wall portion 13. Power is supplied to each part of the heating device 1 by a predetermined external power source via a USB cable connected to the USB terminal 16.

[0025] Instead of such a USB terminal 16, a power terminal to which an AC adapter can be connected may be provided to supply power via the AC adapter. Further, an AC power terminal may be provided instead of the USB terminal 16, and a power circuit (AC-DC converter) may be provided inside the heating device so that power can be supplied from a commercial power source through an AC cord connected to the AC power terminal. Furthermore, a rechargeable secondary battery may be provided inside the heating device so that it can be used as a power source, and the heating device can be used in an environment where other power sources such as a commercial power source cannot be used, for example, outdoors.

[0026] On the other hand, a convex portion 12a is provided on a part of the inner wall portion 12 of the heating tank 10 as a guide for the water level when water is put into the tank space 10a. The upper end position of this convex portion 12a corresponds to the water level when an appropriate amount of water is introduced into the tank space 10a.

[0027] A first temperature sensor 51 is provided at a predetermined portion along the inner wall portion 12 in a gap between the inner wall portion 12 and the outer wall portion 13 of the heating tank 10 corresponding to the back side of the convex portion 12a of the inner wall portion 12, enabling the temperature of the water in the tank space 10a to be detected. The temperature sensor 51 is connected to the circuit board of the control unit 60 and is held by the holder 19 in the same way as the board. When the holder 19 is inserted and fixed in the arrangement space together with the board of the control unit 60, the temperature sensor 51 can be arranged along the back side portion of the convex portion 12a of the inner wall portion 12 without difficulty.

[0028] The first temperature sensor 51 is, for example, a thermistor, and by being provided along the convex portion 12a of the inner wall portion 12, it can detect the temperature of the water contained in the tank space 10a separated by the convex portion 12a of the inner wall portion 12.

[0029] In addition, a second temperature sensor 52 is provided at a position above the USB terminal 16 on the lower part of the outer wall 13 where the USB terminal 16 is located in the heating tank 10, and is connected to the control unit 60. The second temperature sensor 52 is, for example, a thermistor, and is arranged to contact a predetermined inner part of the outer wall 13 directly above the USB terminal 16, so that it can detect the temperature (room temperature) of the indoor space separated from the outer wall 13, which is the ambient temperature around the heating device. This temperature sensor 52 is provided at one end in the longitudinal direction of the heating tank 10 and is arranged away from the heating part 40, so that it is not affected by the heat generated from the heating part 40.

[0030] The protrusions 15 provided on the bottom 11 of the heating tank 10 are arranged in a plurality of linear rows in a direction (transverse direction) perpendicular to the longitudinal direction of the heating tank 10 on the bottom 11 to form a protrusion row, and a plurality of such protrusion rows are arranged at equal intervals in the longitudinal direction of the heating tank 10.

[0031] At least a part of these plurality of protrusions 15 is in contact with the lower surface of the inner container 30 accommodated in the heating tank 10 and supports the inner container 30 from below. And water, which is a heat transfer medium liquid, can flow between the lower surface of the inner container 30 supported by the protrusions 15 and the bottom 11 of the heating tank 10.

[0032] Specifically, the protrusions 15 are arranged in a staggered state in the longitudinal direction of the heating tank 10. Thereby, the gaps between the protrusions 15 are continuous in the transverse direction of the heating tank 10, while being discontinuous in the longitudinal direction of the heating tank 10.

[0033] In this way, since the plurality of protrusions 15 are linearly arranged in the transverse direction of the heating tank 10, the gaps between the protrusions 15 are also continuous in the transverse direction, making it easy for water to flow in the transverse direction of the heating tank 10, while making it relatively difficult for water to move in the longitudinal direction.

[0034] Therefore, the movement associated with the convection of water due to the heat generated by the heating unit 40 at the central portion of the bottom 11 can be promoted in the short side direction of the heating tank 10, and the heat can be concentrated and quickly transferred to the inner container 30. Then, inside the inner container 30, the convection of the object to be heated (fermentation material) is likely to occur earlier, and the temperature inside the inner container 30 can be quickly made uniform.

[0035] Also, since the rows of the plurality of linearly arranged protrusions 15 are directed toward the inner wall portion 12 where the first temperature sensor 51 is located, it is also in a state where the movement associated with the convection of water can be promoted in the direction where the temperature sensor 51 is present. As a result, a water temperature change is likely to occur in the vicinity of the temperature sensor 51, and the generated temperature change can be quickly detected by the temperature sensor 51. The temperature change of the water in the tank space 10a can be quickly acquired by the control unit 60 and reflected in the control of the heating unit 40, enabling appropriate temperature management.

[0036] Each of the protrusions 15 is formed in a tapered shape in which the size of the tip end is smaller than the size of the base end portion. Thereby, the tip end of the protrusion 15 in contact with the lower surface of the inner container 30 comes into point contact or line contact with the inner container 30. Further, since the tip end portion of the protrusion 15 is formed small (thin), the interval between the protrusion tip ends is wider than the interval between the protrusion base ends, and the water 80 moving with the convection easily passes between the protrusion tip ends. On the other hand, since the base end portion of the protrusion 15 is formed large (thick), the situation where the protrusion 15 breaks from the base end portion is less likely to occur.

[0037] Note that the number of the protrusions 15 provided on the bottom 11 may be an arrangement with a number different from the above arrangement as long as the effect of promoting the movement associated with the convection of the heat transfer medium liquid (water) in each direction in which the protrusions 15 are arranged can be sufficiently exerted by the arranged protrusions.

[0038] The lid portion 20 is configured to be able to cover and close the upper opening of the heating tank 10 with the inner container 30 and the water 80 accommodated in the tank space 10a of the heating tank 10. By closing the upper opening of the heating tank 10 with the lid portion 20 and sealing the inner space 10a of the tank, it is possible to make it difficult for the heat to escape from the water 80 and the inner container 30 in the inner space 10a of the tank.

[0039] Depending on the size of the inner container 30 placed in the inner space 10a of the heating tank 10, specifically, when the inner container 30 is large and the lid portion 20 cannot be closed, it may be in a state where it does not cover or close the inner space 10a.

[0040] One or more liquid guiding portions 21 for guiding the water derived from the water droplets adhering to the inner side of the lid portion 20 due to condensation to the inner space 10a side of the heating tank 10 may be provided on the inner portion of the lid portion 20 facing the heating tank 10 (see FIGS. 6 and 7).

[0041] The liquid guiding portion 21 is in a protruding shape protruding from the lid portion 20 toward a portion where the inner container 30 cannot exist in the inner space 10a of the heating tank 10. When the water droplets adhering to the inner side of the lid portion 20 gather and tend to flow down as water, such water flows down along the liquid guiding portion 21 and heads toward the location where the water in the inner space 10a accumulates, so that the water does not leak outside the heating tank 10 and the water does not reach the inner container 30 either, minimizing the wetting of the inner container 30.

[0042] The inner container 30 is a lid-equipped container with sufficient heat resistance that does not deform or deteriorate even when it is housed and heated in the inner space 10a of the heating tank 10. The inner container 30 is a commercially available and generally available known lid-equipped container that can be housed in the heating tank 10 and the heating tank 10 containing this inner container 30 can be closed by the lid portion 20 without difficulty, and detailed description thereof is omitted.

[0043] The heating unit 40 includes two heater units 41 and 42 for heating with a linear conductor foil arranged in a predetermined pattern, a temperature detection unit 43 for temperature detection with a linear conductor foil arranged in a predetermined pattern, and a diffusion unit 44 having a planar conductor foil. The heating unit 40 is formed as a multi-layer substrate with multiple layers in a laminated state of the heater units 41 and 42, the temperature detection unit 43, and the diffusion unit 44, which are of the same size. In the heating unit 40, the conductor foils forming the heater units 41 and 42, the temperature detection unit 43, and the diffusion unit 44 are made of a metal foil such as copper, similar to a general multi-layer substrate, but are not limited to this. For example, materials with a higher electrical resistance may be used for the heater units 41 and 42. Also, although there are two heater units in the heating unit 40, these heater units may be provided in a laminated state with a number more than two, such as three or four.

[0044] The heating unit 40 is disposed below the bottom 11 in the heating tank 10 by being attached with an attaching means such as a double-sided tape formed of a material with good thermal conductivity. In thus providing the heating unit 40 with respect to the heating tank 10 in a state where the inner space 10a of the tank can be heated, since it is only necessary to attach the heating unit 40 to the bottom 11 of the heating tank 10, it can be easily disposed and the cost can be suppressed.

[0045] Note that, in order to prevent the heating unit 40 from accidentally peeling off from the double-sided tape attaching the heating unit 40 to the bottom 11 of the heating tank 10, a predetermined cushioning material may be disposed in a compression-deformed state between the heating unit 40 and the lower lid 14 of the heating tank 10, and the elastic restoring force of the cushioning material supported from below by the lower lid 14 may be used to push the heating unit 40 from below and press the heating unit 40 against the bottom 11 (double-sided tape).

[0046] The heating unit 40 adopts the structure of a multilayer printed circuit board that can easily obtain a laminated structure such as a heater unit and a temperature detection unit, can be easily arranged and fixed in the apparatus, and can reduce costs. However, it is not limited to this, and other laminated structures can also be used. For example, a configuration can be adopted in which a conductive layer serving as a heater and an insulating layer are separately formed and then overlapped and integrated. Also in this case, the heater is a planar one by resistive heating, and as the conductive layer, in addition to copper, aluminum, stainless steel, nichrome wire, etc. can be used. Further, as the insulating layer, a heat-resistant resin film or a silicone material can be overlapped and configured. In addition to this, as the planar heater, a configuration can be adopted in which a so-called polyimide heater, a polyester heater, etc. are employed.

[0047] The heating unit 40 in which the heater units 41 and 42 and the temperature detection unit 43 are formed on an integrated substrate is easy to achieve a uniform temperature due to the structure of the heater units 41 and 42, and in addition, since there is little delay in heat conduction between the heater units 41 and 42 and the temperature detection unit 43, it has excellent controllability and overshoot and undershoot are extremely unlikely to occur.

[0048] Other types of heaters are difficult to control, such as being prone to overshoot, and it is difficult to use them in fermentation applications where temperature management is extremely important because excessive temperature increase or decrease can have an adverse effect. Therefore, the heating unit 40 employing the heater units 41 and 42 is desirable.

[0049] In the heating unit 40, among the heater units 41 and 42 and the temperature detection unit 43 to be laminated, the heater units 41 and 42 are disposed at an inner layer portion between the layer of the temperature detection unit 43 and other layers, while the temperature detection unit 43 is disposed on the surface layer (closer to the outside).

[0050] The entire substrate of the heating unit 40 can be heated by the heating of the heater units 41 and 42 located at the inner layer. Since the heater units 41 and 42 that execute heating are located at the inner layer and cover the outside, a certain heat storage effect can also be expected in the heating unit 40.

[0051] Regarding the structure of the multilayer substrate forming the heating unit 40, at the innermost part of the heating unit 40, conductor foils forming heater units 41 and 42 are stacked on both the front and back sides of the insulating layer 46 as the core material. Further, an adhesive layer (prepreg) 47 is disposed so as to overlap each of the heater units 41 and 42. A temperature detection unit 43 is provided on one side of the adhesive layer, and a diffusion unit 44 is provided on the other side of the adhesive layer, and they are further stacked and provided respectively. Then, the surface of the temperature detection unit 43 and the surface of the diffusion unit 44 are covered with a protective film (solder resist) 48.

[0052] The two heater units 41 and 42 of the heating unit 40 are arranged in a meandering pattern in which a linear conductor foil formed on a thin plate forming the insulating layer 46 is made continuous while being folded back at the end of the thin plate.

[0053] For example, the linear conductor foils of the heater units 41 and 42 are formed with a thickness of 35 μm, a line width of 0.9 mm, and a line interval of 0.5 mm in a meandering pattern. The thickness, line width, and line interval of the linear conductor foil of such a heater unit may be determined by the magnitude of the current flowing through it.

[0054] The two heater units 41 and 42 are electrically connected in parallel as similar resistive loads to the circuit side of the power supply and the control unit 60. However, it is not limited to this, and the two heater units 41 and 42 may be connected in series.

[0055] In the heating unit 40, the continuous direction of each line of the linear conductor foil in one heater unit 41 and the continuous direction of each line of the linear conductor foil in the other heater unit 42 are laminated in an arrangement relationship perpendicular to each other. And among these heater units 41 and 42, one heater unit 41 is located on the side closer to the temperature detection unit 43, and the other heater unit 42 is located on the side farther from the temperature detection unit 43.

[0056] In this way, the linear conductor foils in the two overlapping heater parts 41 and 42 are arranged such that the linear continuity directions of the linear conductor foils are perpendicular to each other, minimizing the overlap of the linear conductor foils in the heater parts 41 and 42 and ensuring the maximum possible apparent area of the linear conductor foils visible from the surface of the heating part. As a result, heat can be generated from a wide range of the heater parts 41 and 42 and transferred to the surface of the heating part 40, enabling heating of the entire surface of the heating part 40 and efficiently heating the water through the bottom 11 of the heating tank 10.

[0057] Incidentally, it is known that when a heater made of a linear metal foil formed on a substrate is in a heated state, there is a possibility of warping of the substrate due to the difference in the linear expansion coefficients between the linear metal foil and the other layers of the substrate. In the multilayer substrate forming the heating part 40 of the present embodiment, the linear continuity directions of the linear conductor foils in the two heater parts 41 and 42 are in a state where they are perpendicular to each other. For this reason, the deformations (warps) that can occur in the substrate due to the heating of each of the heater parts 41 and 42 cancel each other out, and warping of the entire substrate can be prevented.

[0058] If more than two heater parts are provided in a stacked state in the heating part 40, in any of the heater parts to be stacked, the linear continuity directions of the linear conductor foils in two adjacent heater parts in the stacking direction may be arranged to be perpendicular to each other.

[0059] The temperature detection part 43 of the heating part 40 is configured to be arranged as a meandering pattern in which a linear conductor foil formed on a thin plate forming the adhesive layer 47 is made continuous while being folded back at the end of the thin plate, similar to the heater parts 41 and 42. However, the temperature detection part 43 is formed with a smaller line width and interval between lines in the linear conductor foil compared to the linear conductor foil forming the heater parts 41 and 42, so that the length of the linear conductor foil is made larger than the length of the linear conductor foil forming the heater parts 41 and 42.

[0060] For example, the linear conductor foil of the temperature detection unit 43 is formed with a thickness of 18 μm, a line width of 0.15 mm, and a meandering pattern with a spacing between lines of 0.15 mm. In this case, the line length of the temperature detection unit 43 is about 70 m, the resistance value is 80 Ω at 25°C, and 120 Ω at 110°C, and a relatively large change in the resistance value occurs with temperature changes.

[0061] In this way, by making the linear conductor foil of the temperature detection unit 43 extremely long compared to the linear conductor foils of the heater units 41 and 42, the resistance value of the linear conductor foil of the temperature detection unit 43 can be made larger, and the change in the resistance value with temperature changes can also be made larger, enabling fine temperature changes to be captured from the change in the resistance value and improving the temperature detection accuracy.

[0062] By detecting the temperature with the temperature detection unit 43, it is possible to detect heating (dry burning) in a state where there is no water in the tank space 10a or a temperature rise due to abnormal heat generation in the heater units 41 and 42. When water is present in the tank space 10a of the heating tank 10, since the heat of the heating unit 40 is dissipated to the water to warm it, even when the output of the heater units 41 and 42 is maximized, it does not exceed a predetermined upper limit temperature (a temperature at which the heating tank and the inner container do not deform or deteriorate and the water does not boil), ensuring a certain level of safety.

[0063] The diffusion unit 44 is formed of a planar conductor foil, has the same size as the heater units 41 and 42, and is disposed on the side opposite to the side where the temperature detection unit 43 is present with respect to the heater unit 42. The diffusion unit 44 is formed with the thickness of the planar conductor foil thinner than the thickness of the conductor foil in the heater units 41 and 42. For example, the planar conductor foil of the diffusion unit 44 is formed with a thickness of 18 μm.

[0064] By making the thickness of the planar conductor foil in the diffusion unit 44 thinner than the thickness of the linear conductor foils of the heater units 41 and 42, and making it easier for the heat transmitted to a part of the planar conductor foil of the diffusion unit 44 to spread to other parts of the planar conductor foil, the heat can be quickly transmitted to the entire planar conductor foil of the diffusion unit 44 and the heat can be diffused over the entire surface of the heating unit 40, enabling heat to be efficiently transferred from the heating unit 40 to the tank space side of the heating tank 10.

[0065] The diffusion part 44 is electrically connected to a location at the power supply potential or a location at the ground potential in at least one of the heater parts 41 and 42. By this connection, the planar conductor foil of the diffusion part 44 is also set to the power supply potential or the ground potential, so that the planar conductor foil of the diffusion part 44 serves as a shield against external noise, static electricity, etc. In this way, the diffusion part 44 prevents the influence of external noise, static electricity, etc. from reaching the heater parts 41 and 42 of the heating part 40, the temperature detection part 43, and further the electric circuit of the control part 60 through these, enabling these to operate stably and not cause malfunction.

[0066] The heating part 40 is provided below the bottom of the heating tank 10 with one side of this diffusion part 44 facing the inner space 10a side of the heating tank 10. In this way, since the heating part 40 is provided in the heating tank 10 with the diffusion part 44 facing the inner space side of the heating tank 10, the heat generated in the heater parts 41 and 42 can be diffused to the entire surface of the heating part 40 through the diffusion part 44 formed of a planar conductor foil without gaps, and heat can be efficiently transferred from the heating part 40 to the inner space 10a side.

[0067] In this heating part 40, the heater parts 41 and 42, the temperature detection part 43, and the diffusion part 44 are made to have substantially the same size, so that the heater parts 41 and 42 can transfer heat to the diffusion part 44 without waste and warm the diffusion part 44 efficiently, and the temperature of the heater parts 41 and 42 can be appropriately detected by the temperature detection part 43.

[0068] In addition, when the bottom 11 of the heating tank 10 is sufficiently large with respect to the heating part 40, in order to facilitate heat transfer from the heating part 40 to the bottom 11, the diffusion part 44 can also be configured to be larger than the heater parts 41 and 42.

[0069] In addition, although the heating unit 40 is configured such that the side with the diffusion unit 44 faces the inner space 10a side of the heating tank 10, it is not limited to this. For example, when the heat diffusion performance by the diffusion unit 44 is not emphasized, the heating unit 40 may be provided such that the side with the temperature detection unit 43 faces the inner space 10a side of the heating tank 10.

[0070] The temperature sensor 51 is disposed along the inner wall portion 12 of the heating tank 10 and measures the temperature of water (water temperature) as the heat transfer medium. Regarding this temperature sensor 51, it can be said that the protrusions 15 of the heating tank 10 are arranged linearly facing the inner wall portion 12 where the temperature sensor 51 exists in the heating tank 10.

[0071] As temperature control, the control unit 60 uses the temperature set according to the object to be heated as the target value, and controls the outputs of the heater units 41 and 42 of the heating unit 40 so that the temperature of the water obtained based on the detection by the first temperature sensor 51 and the temperature assumed in the inner container 30 remain within the allowable temperature range including the target value.

[0072] Actually, the control unit 60 performs control to finely switch between the temperature rising state and the temperature falling state so that the temperature of the water reaches the target value in the temperature rising state at the start of heating for the heater units 41 and 42 of the heating unit 40, and then the temperature of the water remains within the allowable temperature range including the target value.

[0073] The temperature rising state is a state where the heater units 41 and 42 actively heat to raise the temperature of the water, and the temperature falling state is a state where the heater units 41 and 42 slightly heat or completely stop heating to lower the temperature of the water. At the start of heating of the heating unit 40, the control unit 60 performs control called soft start to gradually increase the duty ratio of the output so as not to cause an excessive temperature change.

[0074] The temperature setting range by this control unit 60 (the temperature setting range that can be set by the user through the operation unit) is a range corresponding to heating and keeping warm for various objects to be heated, for example, 40 to 70 °C. Also, the allowable range (swing width) with respect to the target value in temperature control is, for example, ±5%.

[0075] Further, based on the ambient temperature of the heating tank 10 detected by the second temperature sensor 52, the control unit 60 can increase or decrease the outputs of the heater units 41 and 42 in the heating unit 40 by PWM control.

[0076] Specifically, based on the ambient temperature of the heating tank 10 (for example, the indoor temperature) detected by the second temperature sensor 52, the control unit 60 adjusts and controls the duty ratio of the output voltage (current) of the heater units 41 and 42 in the heating unit 40 to increase or decrease the heating degree. When the ambient temperature is high, the control unit 60 reduces the duty ratio of the output voltage (current), and when the ambient temperature is low, the control unit 60 increases the duty ratio of the output voltage (current).

[0077] More specifically, when the indoor temperature as the ambient temperature measured by the temperature sensor 52 is sufficiently high (for example, 25 °C or higher), the natural heat dissipation amount to the outside of the heating device is small, and the temperature of the water tends to rise due to heating. In such a case, the duty ratio of the output of the heater units 41 and 42 in the heating unit 40 in the temperature rising state of raising the temperature of the water is less than 100%, and is adjusted to be smaller as the indoor temperature becomes higher. And since the fact that the natural heat dissipation amount to the outside of the heating device is small also means that the temperature of the water is not likely to drop, the duty ratio of the output of the heater units 41 and 42 in the temperature lowering state of lowering the temperature of the water is 0%, that is, in the OFF state at any indoor temperature so as to make the temperature easy to drop.

[0078] In a situation where the indoor temperature is high, by reducing the duty ratio of the output and suppressing the generation of heat, it is possible to suppress the excessive rise in the temperature of the water in the temperature rising state, and it is possible to promote the temperature drop in the temperature lowering state.

[0079] Conversely, when the indoor temperature measured by the temperature sensor 52 is low (for example, less than 25°C), the natural heat dissipation amount to the outside of the heating device becomes relatively large, and it is difficult for the temperature of the water to rise even when heated. In such a case, the duty ratio of the output in the heater units 41 and 42 of the heating unit 40 in the temperature rising state for raising the temperature of the water is set to 100% at any indoor temperature so as to compensate for the difficulty in temperature rise. And since the natural heat dissipation amount to the outside of the heating device is large, the temperature of the water is likely to drop. Therefore, the duty ratio of the output in the heater units 41 and 42 in the temperature lowering state for lowering the temperature of the water is made larger than 0% so that the temperature does not drop too much, and it becomes larger as the indoor temperature becomes lower.

[0080] In a situation where the indoor temperature is low, by increasing the duty ratio of the output and increasing the generation of heat, it becomes possible to compensate for the amount of heat dissipated to the outside (the indoor space side), and in the temperature rising state, the temperature of the water can be appropriately raised, and in the temperature lowering state, it is possible to suppress the excessive decrease in the temperature of the water.

[0081] For example, when the room temperature is 25°C, in the temperature rising state, the duty ratio of the output in the heater units 41 and 42 is 95%, and in the temperature lowering state, the duty ratio of the output is 0%. On the other hand, when the room temperature is 35°C, in the temperature rising state, the duty ratio of the output in the heater units 41 and 42 is set to 85%. And in the temperature lowering state for lowering the temperature of the water, as in the case of 25°C, the duty ratio is 0%.

[0082] Also, for example, when the room temperature is 20°C, in the temperature rising state, the duty ratio of the output in the heater units 41 and 42 is 100%, and in the temperature lowering state, the duty ratio of the output is 5%. On the other hand, when the room temperature is 5°C, in the temperature rising state, as in the case of 20°C, the duty ratio is 100%. And in the temperature lowering state, the duty ratio of the output in the heater units 41 and 42 is set to 20%.

[0083] When the indoor temperature is low, the amount of heat lost due to heat dissipation from the heating tank 10, which is at a higher temperature, to the outside indoor space increases. Therefore, if the heater unit output of the heating unit 40 is completely set to 0 in order to lower the temperature of the water in the cooling state, the degree of temperature drop in the heating tank 10 will increase, and the temperature of the water may drop too much. On the other hand, even when lowering the temperature of the water, by keeping the heater units 41 and 42 in the heating continuous state with a weak output, the heat lost due to heat dissipation to the indoor space can be compensated, the temperature drop can be slowed down, and excessive temperature drop can be prevented.

[0084] Particularly when manufacturing fermented foods, if the fermentation temperature in the inner container 30 is not kept uniform by the heating of the heating unit 40, the fermentation of the material will not proceed and the desired food cannot be produced. Therefore, it is desirable to be able to prevent excessive temperature drop, and the above temperature control is effective.

[0085] The heat of the heating unit 40 is transmitted to the inner container 30 from the bottom 11 of the heating tank 10 through direct heat conduction through the protrusions 15, indirect heat conduction through water, and heat radiation from the surface of the bottom 11. However, from the comparison verification results depending on the presence or absence of water, it has been found that the ratio of indirect heat conduction through water in the whole heat transfer is the largest.

[0086] By using the temperature of the indoor space around the heating device detected by the second temperature sensor 52 provided along the outer wall portion 13 of the heating tank 10 for temperature control in the control unit 60, the heating unit 40 can be controlled according to the room temperature, and the control temperature range can be reduced.

[0087] In addition, based on the indoor temperature measured by the second temperature sensor 52, the control unit 60 can also perform control to adjust the threshold values (upper limit value and lower limit value) related to the allowable temperature range of the water temperature in the temperature control. For example, when the indoor temperature is lower than normal temperature (25 °C), since the amount of natural heat dissipation to the outside of the heating device relatively increases, the control unit 60 sets the upper limit value and the lower limit value of the temperature range higher than those in the case of normal temperature, so that the amount of heat can be compensated. The control unit 60 may execute the adjustment control of the upper limit value and the lower limit value of such a temperature range in combination with the duty ratio adjustment control of the heater unit output described above.

[0088] Next, the usage state of the heating device according to this embodiment will be described. As a premise, the heating device 1 has a cable connected to a USB terminal provided at the lower part of the outer wall portion 13 of the heating tank 10, and receives power supply from an external power supply device (not shown) as a power supply means via this cable, and is in a state where power can be supplied to the heating unit 40 and the control unit 60. Also, it is assumed that the inner space 10a of the heating tank 10 is initially closed by the lid portion 20 with the inner container 30 and the water 80 not being accommodated.

[0089] In the heating device according to this embodiment, examples of the object to be heated 90 that is heated and kept warm in the heating tank 10 with the inner container 30 placed therein include chemicals and foods. Specific examples of foods include fermented foods such as yogurt, natto, cheese, and amazake that can be stored in the inner container 30, confectionery materials (such as chocolate and cheese), and unpackaged foods for making hot water extracts, which can be used as the object to be heated.

[0090] In addition, by using a baby bottle as the inner container, milk can be used as the object to be heated, or by using a decanter or a sake cup as the inner container, sake can be used as the object to be heated.

[0091] With the lid portion 20 removed from the heating tank 10 and the inner space 10a of the tank opened, the inner container 30 containing the yogurt raw materials (milk and starter) as the object to be heated 90 is placed in the inner space 10a of the heating tank 10. Subsequently, water 80 is put into the inner space 10a of the heating tank 10 so that the water level reaches the upper end of the convex portion 12a of the inner wall portion 12.

[0092] After putting in the water, the lid portion 20 is attached to the heating tank 10 again to close the inner space 10a containing the inner container 30 and the water 80. Then, an operation is performed on the operation portion on the side surface of the heating tank 10 to set the target temperature and the duration corresponding to the object to be heated.

[0093] Receiving the temperature and time settings, the control unit 60 starts energizing the heater units 41 and 42 of the heating unit 40. Due to the energization, the heater units 41 and 42 enter the heating state, and the heat generated by the heater units 41 and 42 is transmitted to each part of the heating unit 40. Then, heat is transmitted from the entire heated heating unit 40 to the bottom 11 of the heating tank 10, and further from the bottom 11 of the heating tank 10 to the water 80.

[0094] In this way, by heating the water 80 in the tank inner space 10a by the heating unit 40, convection of the water 80 heated by the heating unit 40 occurs. The warmed water first moves in the short side direction where it is easier to flow along with the convection from the center of the heating tank 10 near the heating unit 40, and the temperature of the water 80 from the center of the heating tank to the vicinity of the inner side wall portion at the short side end rises. Furthermore, such warmed water 80 spreads to each part of the tank inner space 10a, and the temperature of the entire water rises.

[0095] In the process where the water 80 heated by the heating unit 40 moves in the short side direction from the center of the heating tank 10 along with the convection and reaches the inner side wall portion 12 at the short side end, the inner container 30 is also heated by the warmed water 80, so that the temperature of the object to be heated 90 in the inner container 30 can be rapidly increased.

[0096] The control unit 60 controls the heating state of the heating unit 40 so that the temperature of the object to be heated 90 reaches an appropriate temperature that meets the purpose such as fermentation within a predetermined time, and adjusts the temperature of the water 80 detected by the first temperature sensor 51 to approach the target value corresponding to the object to be heated 90.

[0097] After the temperature of the water 80 once reaches the target value, the control unit 60 controls the energization state of the heater units 41 and 42 of the heating unit 40 based on the temperature of the water 80 detected by the first temperature sensor 51 and the indoor air temperature detected by the second temperature sensor 52, so as to maintain the temperature of the water 80 within the allowable range corresponding to the target value. At the same time, the control unit 60 monitors the temperature of the heating unit 40 detected by the temperature detection unit 43 to prevent the heater units 41 and 42 from entering an abnormal overheating state.

[0098] When the water 80 is heated in the heating tank 10, a part of the water 80 evaporates, and the generated water vapor may condense inside the lid portion 20 to form water droplets. When the water 80 derived from such water droplets flows downward from the lid portion 20, it is guided to the side of the tank inner space 10a through the guide portion 10c at the corner of the heating tank 10, so it does not flow out to the outside.

[0099] When the control unit 60 reaches a stage where the output control of the heater units 41 and 42 of the heating unit 40 is performed so as to maintain the temperature of the water 80 within the allowable range and a predetermined time set in advance has elapsed and the temperature maintenance of the object to be heated 90 can be terminated, the control unit 60 stops energizing the heating unit 40. When the object to be heated is a yogurt raw material, when the fermentation of them progresses and is completed as yogurt, the control unit 60 will stop energizing the heating unit 40.

[0100] After stopping the energization of the heating unit 40, remove the lid portion 20 from the heating tank 10 to open the tank inner space 10a, and take out the inner container 30 from the tank inner space 10a. If necessary, the inner container 30 containing a new object to be heated may be placed in the tank inner space 10a of the heating tank 10, and the same process may be repeated.

[0101] When discharging the water 80 contained in the tank inner space 10a of the heating tank 10, by using the drainage portion (concave portion) 10b provided at the corner of the heating tank 10 to let it flow out, when the heating tank 10 is tilted, the water flow can be concentrated on the drainage portion 10b and the outflow width can be suppressed to let it flow out. Thereby, the water flowing out from the edge of the heating tank 10 does not spread horizontally and deviate from the desired discharge target position, and does not wet an unexpected location.

[0102] By using the inner container 30, after heating the object to be heated 90 with the heating device 10, the water attached to the inner container 30 can be wiped off and then the inner container 30 can be directly put into the refrigerator as it is, eliminating the need for transfer, which is excellent in terms of usability.

[0103] As described above, in the heating device according to this embodiment, the inner container 30 is supported by the protrusions 15 protruding from the bottom 11 of the heating tank 10, and water 80 as a heat transfer medium liquid can flow through the gap corresponding to the height of the protrusions 15 formed between the bottom 11 of the heating tank 10 and the lower surface of the inner container 30. Since the water 80 heated by the heating unit 40 transfers heat to the inner container 30 from the contact portions between the water 80 and the inner container 30 on the lower surface and the side surface of the inner container 30, convection of the water 80 occurs even below the inner container 30 floating away from the bottom 11 of the heating tank 10, the temperature of the water 80 easily rises, and the object to be heated in the inner container 30 can be uniformly heated.

[0104] In the heating device according to the above embodiment, the heating tank 10 is configured as a substantially box-shaped body having a substantially rectangular shape in plan view. However, the present invention is not limited to this, and the heating tank may be formed in a shape other than a substantially rectangular shape in plan view, for example, a square or other polygon, or a shape including an arc in part. Further, the heating tank may be formed in a shape without corners in plan view, for example, a circular shape (see FIG. 16), an elliptical shape, or an oval shape.

[0105] In the heating device according to the above embodiment, the protrusions 15 are arranged such that the direction of the rows (protrusion rows) in which the plurality of protrusions 15 provided on the bottom of the heating tank 10 are linearly arranged coincides with the short side direction of the heating tank 10. However, the present invention is not limited to this, and the arrangement state of the protrusions on the bottom 11 may be changed.

[0106] For example, as shown in FIG. 17, a configuration may be adopted in which a plurality of protrusions are arranged in a straight line in the longitudinal direction of the heating tank 10, and a plurality of rows of such protrusion rows are arranged at equal intervals in a direction orthogonal to the longitudinal direction of the heating tank 10. In this case, it is possible to promote the movement based on the convection of water to the longitudinal ends of the heating tank 10 where the heating unit does not exist, and the water temperature can be made uniform.

[0107] Further, in the heating device according to the above embodiment, a plurality of protrusions 15 are arranged linearly in a direction orthogonal to the longitudinal direction of the heating tank 10 to form a protrusion row, and a plurality of rows of these protrusion rows are arranged at equal intervals in the longitudinal direction of the heating tank 10, and are configured to be in a staggered arrangement when viewed from the longitudinal direction of the heating tank 10. However, the present invention is not limited to this, and other arrangements, for example, a lattice arrangement as shown in FIGS. 18 and 19, etc., may be adopted to provide protrusions.

[0108] As shown in FIG. 18, when the protrusions 15 are linearly arranged in a direction orthogonal to the longitudinal direction of the heating tank 10, that is, in the short-side direction, the gaps between the protrusions are continuous in the short-side direction of the heating tank 10, thereby promoting the flow of water in the short-side direction of the heating tank 10. On the other hand, in this lattice arrangement, since there are continuous gaps also in the longitudinal direction of the heating tank 10, a part of the flow of water in this longitudinal direction can be allowed, causing movement based on the convection of water to the longitudinal ends of the heating tank 10.

[0109] Also, as shown in FIG. 19, when the protrusions are linearly arranged in the longitudinal direction of the heating tank 10, the gaps between the protrusions are continuous in the longitudinal direction of the heating tank 10, thereby promoting the flow of water in the longitudinal direction of the heating tank 10. And, being in a lattice arrangement, there are also continuous gaps in the short-side direction of the heating tank 10, and a part of the flow of water in this short-side direction is also allowed, causing movement based on the convection of water in the short-side direction of the heating tank 10.

[0110] Further, in the heating device according to the above embodiment, the plurality of protrusions are all configured to be linearly arranged in a direction orthogonal to the longitudinal direction of the heating tank 10. However, the present invention is not limited to this, and in addition, the directions in which the plurality of protrusions are arranged may be mixed, with some being parallel to the longitudinal direction of the heating tank and some being parallel to the short-side direction of the heating tank.

[0111] For example, the center of the bottom may be hollowed out and a plurality of protrusions may be formed around it, and the arrangement of the protrusions may be an arrangement combining those with different directions in which the protrusions are arranged (see FIG. 20). In this arrangement example, while diffusing the heat generated at the center of the bottom in the short-side direction, it promotes the flow of water to the longitudinal ends without a heating section.

[0112] (Second Embodiment of the Present Invention) In the heating device according to the above embodiment, the sizes and shapes of the protrusions 15 provided on the bottom 11 of the heating tank 10 are all the same, but the present invention is not limited to this, and the sizes and shapes of the protrusions 15 may be made different depending on the part of the bottom 11. For example, as the protrusions, a configuration including a first protrusion 15a having a predetermined height and a second protrusion 15b having a height lower than that of the first protrusion 15a can be adopted.

[0113] The first protrusion 15a is formed higher than the second protrusion 15b and contacts the lower surface of the inner container 30 accommodated in the heating tank 10 to support the inner container 30. On the other hand, the second protrusion 15b is made lower than the first protrusion 15a and does not contact the lower surface of the inner container 30 accommodated in the heating tank 10.

[0114] Here, for example, a configuration can be adopted in which the second protrusion 15b is provided at the center of the bottom 11 of the heating tank 10 and the first protrusion 15a is provided around the center of the bottom 11. That is, a configuration in which a plurality of protrusions 15a and 15b are formed such that the height of the protrusion 15a around the center of the bottom is made larger than the height of the protrusion 15b at the center of the bottom of the heating tank 10 (see FIG. 21).

[0115] In this case, the second protrusion 15b located at the center of the bottom 11 allows water (heat medium liquid) to pass between its upper part and the inner container 30, while the surrounding first protrusion 15a has its tip in contact with the lower surface of the inner container 30 to support the inner container 30, and the whole of the protrusion becomes an obstacle to water.

[0116] In this case, based on the property that the central part of the heating unit 40 generates the most heat, a second lower protrusion 15b that is less likely to impede the flow of water is disposed at the central part of the bottom 11. By doing so, the movement of the hot water heated at the central part to the surroundings due to the convection of the hot water is promoted, and the inner container 30 can be quickly warmed by the hot water.

[0117] Also, as another protrusion, a third protrusion 15c is provided at the central part of the bottom 11 of the heating tank 10, while a fourth protrusion 15d is provided around the central part of the bottom 11. The size of the fourth protrusion 15d around the central part of the bottom is formed to be larger than the size of the third protrusion 15c at the central part of the bottom (see Fig. 22).

[0118] In this case, the third protrusion 15c located at the central part of the bottom 11 is small, making it easier for water (heat medium liquid) to pass through the periphery of the protrusion (between the protrusions and between the protrusion and the inner container). On the other hand, the surrounding fourth protrusion 15d is larger, so that the tip of the protrusion contacts the lower surface of the inner container 30 to support the inner container 30, while the whole protrusion becomes an obstacle to water, creating a state where water hardly flows between the protrusions.

[0119] In this case, based on the property that the central part of the heating unit 40 generates the most heat, a third smaller protrusion 15c that is less likely to impede the flow of water is disposed at the central part of the bottom 11. By doing so, the movement of the hot water heated at the central part to the surroundings due to the convection of the hot water is promoted, and the inner container 30 can be quickly warmed by the hot water.

[0120] In addition, the protrusions on the bottom 11 of the heating tank 10 may be provided such that the protrusion arrangement density around the central part of the bottom is made larger than the protrusion arrangement density at the central part of the bottom. Also in this case, by relatively reducing the protrusion arrangement density at the central part of the bottom 11 to make it less likely to impede the flow of water, the movement of the hot water heated at the central part to the surroundings due to the convection of the hot water is promoted, and the inner container 30 can be quickly warmed by the hot water.

[0121] Furthermore, in the heating device according to the above embodiment, the planar shape of the protrusion is formed as an elongated oval shape, but it is not limited to this. As shown in FIG. 23, the protrusion 17 can be formed in a circular shape, or the protrusion can be formed in a polygonal shape such as an elliptical shape or a rectangular shape.

[0122] (The third embodiment of the present invention) In the heating device according to the above embodiment, the inner container 30 and the water 80 are accommodated in the tank inner space 10a of the heating tank 10, and the object to be heated placed in the inner container can be heated through the water and the inner container. However, as a third embodiment, as shown in FIG. 24, the object to be heated 91 and water (not shown) can be accommodated in the tank inner space 10a without using the inner container, and the object to be heated 91 can be heated through the water.

[0123] In this case, as a specific example of the object to be heated 90 that is heated and kept warm in the heating tank 10 with the object to be heated 91 placed directly in the water, there are low-temperature cooked foods (onsen eggs, soft-boiled eggs, roast beef, chicken, etc.), packaged simmered cooked foods, and the like.

[0124] In addition, the heating in the heating tank 10 can be simply used to warm the object to be heated to a predetermined temperature. For example, a retort food as the object to be heated can be warmed, or a frozen food as the object to be heated can be thawed.

[0125] Also in the heating tank 10 when the object to be heated 91 and water are accommodated in the tank inner space 10a and heated in this way, the protrusions 15 are formed to be linearly arranged in the short-side direction of the heating tank 10 in the same manner as in the first embodiment.

[0126] With such a protrusion arrangement, for example, when an egg as the object to be heated 91 is placed in the tank inner space 10a of the heating tank 10 and heated, the arranged protrusions 15 make it difficult for the egg to roll in the longitudinal direction of the heating tank 10, and the range in which the egg rolls and moves can be narrowed. As a result, the egg can be prevented from moving out of the region where the heating part 40 of the bottom 11 is located, and heating can be performed efficiently.

[0127] The heating device according to the disclosure of the present invention, specifically shown in each of the first to third embodiments, can be expected to contribute to the achievement of, for example, "Goal 9: Build the infrastructure for industry and technological innovation (build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation)" among the 17 goals defined by the United Nations in the "Sustainable Development Goals (SDGs)".

[0128] The possible forms of the heating device according to the disclosure of the present invention are appended again.

[0129] The heating device according to the disclosure of the present invention includes an inner container capable of accommodating a predetermined object to be heated therein, a heating tank capable of accommodating the inner container and a predetermined heat medium liquid in a tank space, and a heating unit capable of heating the heat medium liquid accommodated in the tank space of the heating tank. A plurality of protrusions protruding into the tank space are formed on the bottom of the heating tank, and at least a part of the plurality of protrusions is in contact with the lower surface of the inner container accommodated in the heating tank to support the inner container, making it possible for the heat medium liquid to flow between the bottom of the heating tank and the lower surface of the inner container. The heat medium liquid has a predetermined storage capacity such that it can come into contact with the side surface of the inner container in the tank space of the heating tank.

[0130] Thus, according to the disclosure of the present invention, the inner container is supported by the protrusions protruding from the bottom of the heating tank, and the heat medium liquid can flow through the gap corresponding to the height of the protrusions formed between the bottom of the heating tank and the lower surface of the inner container. The heat medium liquid heated by the heating unit transfers heat to the inner container from the contact points between the heat medium liquid and the inner container on the lower surface and the side surface of the inner container. As a result, convection of the heat medium liquid occurs even under the lower side of the inner container floating away from the bottom of the heating tank, making it easy for the temperature of the heat medium liquid to rise, and enabling the object to be heated to be uniformly heated through the inner container.

[0131] In addition, the heating device according to the disclosure of the present invention includes a heating tank capable of accommodating a predetermined object to be heated and a predetermined heat medium liquid in an inner space, a heating unit capable of heating the heat medium liquid accommodated in the inner space of the heating tank, a temperature sensor provided along an inner wall facing the inner space of the heating tank for detecting the temperature of the heat medium liquid, and a control unit for controlling the heating unit based on the temperature detected by the temperature sensor. A plurality of protrusions protruding into the inner space are formed at the bottom of the heating tank, and the protrusions are provided in an arrangement in which a plurality of protrusion rows in which the protrusions are arranged linearly toward the inner wall on the side where the temperature sensor is present in the heating tank are further arranged in parallel in a plurality of rows.

[0132] Thus, according to the disclosure of the present invention, the protrusions provided at the bottom of the heating tank are arranged linearly toward the inner wall where the temperature sensor is present to form a protrusion row, and further, a plurality of such protrusion rows are arranged in parallel. By making it easier for the heat medium liquid that tries to move by convection due to heat to be guided to the protrusion row, the heat medium liquid that tries to convect in the heating tank is directed in the direction of the temperature sensor, creating a situation where the temperature change of the heat medium liquid based on heating is likely to occur near the temperature sensor, making it possible to easily detect the temperature change of the heat medium liquid with the temperature sensor and appropriately control the heating state by the heating unit with the control unit.

[0133] In addition, the heating device according to the disclosure of the present invention, if necessary, the heating tank is formed in an upper surface open box shape that is substantially rectangular in plan view, and the protrusions are provided at the bottom of the heating tank in an arrangement in which a plurality of protrusion rows in which the protrusions are arranged linearly in a direction orthogonal to the longitudinal direction of the heating tank are further arranged in the longitudinal direction of the heating tank in a plurality of rows in parallel.

[0134] Thus, according to the disclosure of the present invention, it is possible to control the convection of the liquid heat medium with the protrusions, convect the heat generated at the central part of the heating tank having a rectangular shape in plan view in the short side direction of the heating tank, concentrate the heat, quickly transfer the heat to the container, easily cause convection in the liquid object to be heated inside the container at an early stage, and quickly make the temperature of the object to be heated in the container uniform.

[0135] In addition, when heating an egg as an object to be heated and a heat transfer medium liquid in a heating tank, the presence of the protrusions can restrict the rolling width of the egg to a narrow range, making it difficult for the egg to roll in the longitudinal direction of the heating tank, and enabling efficient heating in the heating section.

[0136] Moreover, as required, in the heating device according to the disclosure of the present invention, the protrusions are arranged in a staggered pattern in the longitudinal direction of the heating tank.

[0137] Thus, according to the disclosure of the present invention, the protrusions are provided on the bottom of the heating tank in a staggered pattern in the longitudinal direction of the heating tank, without creating continuous gaps in the longitudinal direction. As a result, the water that is heated by the heat from the heating section and attempts to move as convection is obstructed by the protrusions in its path so that it does not move linearly in the longitudinal direction of the heating tank, promoting the convection of water near the container and evenly warming the object to be heated in the container.

[0138] Moreover, as required, the heating device according to the disclosure of the present invention includes a temperature sensor disposed along the inner wall of the heating tank for measuring the temperature of the heat transfer medium liquid, and a plurality of the protrusions are arranged linearly facing the inner wall where the temperature sensor is located.

[0139] Thus, according to the disclosure of the present invention, a temperature sensor for measuring the temperature of the heat transfer medium liquid is provided on the inner wall of the heating tank, and the protrusions arranged linearly in a plurality and facing the temperature sensor cause the movement due to the convection of the heated water to also be directed towards the temperature sensor, facilitating the grasping of the temperature change of the water by the temperature sensor.

[0140] Moreover, as required, the heating device according to the disclosure of the present invention includes at least a first protrusion having a predetermined height and a second protrusion having a height lower than that of the first protrusion.

[0141] According to the disclosure of the present invention as described above, when a plurality of protrusions provided at the bottom of the heating tank have different heights depending on their arrangement positions, and a container containing a heated part and a heat transfer medium liquid are present in the heating tank, the protrusions with a greater height restrict the movement associated with the convection of the heat transfer medium liquid, while the protrusions with a smaller height allow the movement of the heat transfer medium liquid and move it in a desired direction, enabling appropriate heating.

[0142] Further, according to the heating device related to the disclosure of the present invention, if necessary, the protrusions are arranged such that the height of the protrusions at the periphery of the central part of the bottom of the heating tank is made greater than the height of the protrusions at the central part of the bottom of the heating tank.

[0143] According to the disclosure of the present invention as described above, while reducing the height of the protrusions provided at the center of the bottom of the heating tank, the height of the protrusions provided at the peripheral part deviated from the center of the bottom is increased, and by optimizing the protrusion distribution for the heating characteristics in which the heat transfer from the heating part is maximized at the center of the bottom of the heating tank, in addition to the fact that the heat transfer medium liquid heated at the center of the bottom is less likely to be inhibited by the protrusions and thus easily progresses to the periphery by convection, the moving speed is slowed down by the regulation by the protrusions in the peripheral part where the temperature of the heat transfer medium liquid has increased, and heat is transferred to the heat transfer medium liquid with a lower temperature and the container in the periphery, enabling the heat transfer medium liquid and the container to be heated evenly.

[0144] Further, according to the heating device related to the disclosure of the present invention, if necessary, the protrusions are arranged such that the size of the base end part of the protrusions at the periphery of the central part of the bottom of the heating tank is made greater than the size of the base end part of the protrusions at the central part of the bottom of the heating tank.

[0145] According to the disclosure of the present invention as described above, while reducing the base end part of the protrusions provided at the central part of the bottom of the heating tank, the base end part of the protrusions provided at the peripheral part deviated from the central part of the bottom is increased, and by optimizing the size of the protrusions for the heating characteristics in which the heat transfer from the heating part is maximized at the central part of the bottom of the heating tank, in addition to the fact that the heat transfer medium liquid heated at the center of the bottom is less likely to be inhibited by the small protrusions and thus easily progresses to the periphery by convection, the moving speed is slowed down by the regulation by the large protrusions in the peripheral part where the temperature of the heat transfer medium liquid has increased, and heat is transferred to the heat transfer medium liquid with a lower temperature and the container in the periphery, enabling the heat transfer medium liquid and the container to be heated evenly.

[0146] Further, the heating device according to the disclosure of the present invention, as necessary, has the protrusion formed in a tapered shape in which the size of the tip of the protrusion is smaller than the size of the base end portion of the protrusion.

[0147] Thus, according to the disclosure of the present invention, the protrusion provided at the bottom of the heating tank has a tapered shape with a smaller tip portion relative to its base end portion. When using a container, the tip portion of the protrusion contacts the lower surface of the container with a minimum contact area, so that the movement associated with the convection of the heated heat transfer medium liquid is less likely to be hindered at the tip portion of the protrusion, the temperature of the heat transfer medium liquid can be efficiently increased, and appropriate heating can be performed through the heat transfer medium liquid. In addition, since the base end portion of the protrusion is thicker than the tip portion, the strength of the protrusion can be increased, and it can be made less likely to break.

[0148] Further, the heating device according to the disclosure of the present invention, as necessary, is configured such that the density of the protrusions provided around the central portion of the bottom of the heating tank is greater than the density of the protrusions provided at the central portion of the bottom of the heating tank.

[0149] Thus, according to the disclosure of the present invention, while reducing the density of the protrusions provided at the center of the bottom of the heating tank, the density of the protrusions provided in the peripheral portion away from the center of the bottom is increased, and by optimizing the density distribution of the protrusions to the heating characteristics in which the heat transfer from the heating portion is maximized at the center of the bottom of the heating tank, the heated heat transfer medium liquid at the center of the bottom can easily progress to the surroundings by convection because it is not hindered by the sparsely arranged protrusions. In addition, in the peripheral portion where the heat transfer medium liquid with increased temperature has progressed, while the movement speed is slowed down by the regulation by the densely arranged protrusions, heat is transferred to the heat transfer medium liquid with a low temperature in the surroundings and the container, and the heat transfer medium liquid and the container can be heated evenly.

[0150] Further, the heating device according to the disclosure of the present invention, as necessary, is provided with a temperature sensor for measuring the ambient temperature around the heating tank along the outer wall facing the external space of the heating tank.

[0151] According to the disclosure of the present invention as described above, by providing a temperature sensor that measures the temperature of the ambient atmosphere along the outer wall of the heating tank and controlling the heating unit based on the detected temperature, for example, when the temperature of the atmosphere around the heating tank is high, the degree of heat dissipation from the heating tank to the outside is small, and even if the heating capacity of the heating unit is small, the output of the heating unit can be lowered to suppress the heating capacity. On the other hand, when the temperature of the atmosphere around the heating tank is low, the degree of heat dissipation from the heating tank to the outside increases, and when heating capacity is required, the output of the heating unit is increased to increase the heating capacity. In this way, it is not necessary to overly expand the control temperature range of the heating unit, and heating can be performed efficiently.

[0152] Further, according to the disclosure of the present invention, the heating device may, if necessary, be such that the heating unit can adjust the heating output by increasing or decreasing it by PWM control based on the ambient atmosphere temperature of the heating tank detected by the temperature sensor, and the duty ratio of the output is adjusted so that the higher the ambient atmosphere temperature, the smaller the duty ratio, and the lower the ambient atmosphere temperature, the larger the duty ratio.

[0153] According to the disclosure of the present invention as described above, the heating output in the heating unit is adjusted by PWM control based on the ambient atmosphere temperature, and the duty ratio of the output is adjusted to be smaller or larger corresponding to the high or low ambient atmosphere temperature to change the heating capacity. Thus, when the temperature of the atmosphere around the heating tank is high, the degree of heat dissipation from the heating tank to the outside is small, and even if the heating capacity is small, the duty ratio can be made smaller to suppress the heating capacity and the energy consumption related to heating can be suppressed. On the other hand, when the temperature of the atmosphere around the heating tank is low, the degree of heat dissipation from the heating tank to the outside is large, and when heating capacity is required, the duty ratio can be made larger to ensure a high heating capacity. The control temperature range of the heating unit can be made smaller to appropriately execute the control, and the energy consumption of the heating unit can be optimized to perform heating efficiently.

[0154] Further, according to the disclosure of the present invention, the heating device may, if necessary, be provided with a lid portion that can cover and close the upper opening of the heating tank.

[0155] According to the disclosure of the present invention as described above, a lid portion covering the upper opening in the heating tank is provided to be openable and closable. When placing the inner container or the object to be heated in the heating tank, the upper opening of the heating tank with the inner container or the object to be heated is closed by the lid portion, and the space inside the heating tank with the inner container or the object to be heated is closed. Thus, heat dissipation from the opening can be prevented by the lid portion, heat loss can be suppressed, heating can be performed efficiently, and the cost related to heating can be suppressed.

[0156] Moreover, the heating device according to the disclosure of the present invention, as required, forms a guiding portion, which is an inclined surface descending toward the space inside the tank, at a predetermined portion on the upper part of the heating tank that faces the lid portion in a closed state where the lid portion covers the upper opening of the heating tank.

[0157] According to the disclosure of the present invention as described above, by providing an inward inclined surface that inclines toward the space inside the heating tank as a guiding portion at the upper part of the heating tank, even when vapor evaporated from the heat medium liquid heated in the heating tank condenses inside the lid covering the heating tank to form droplets, the droplets of the heat medium liquid that flow down from the lid portion and reach the upper part of the heating tank can be made to flow down into the space inside the heating tank by the guidance of the guiding portion, and it is possible to prevent the liquid derived from the droplets from reaching outside the heating tank.

[0158] Moreover, the heating device according to the disclosure of the present invention, as required, forms a liquid guiding portion on the inner part of the lid portion that faces the space inside the heating tank in a closed state where the lid portion covers the upper opening of the heating tank, and guides the droplets of the heat medium liquid adhering to the lid portion toward the space inside the heating tank near the inner wall of the heating tank.

[0159] According to the disclosure of the present invention, by providing a liquid guiding portion that faces a predetermined portion facing the inner space of the heating tank of the lid portion and directs the liquid droplets toward the inner space of the heating tank, even when vapor evaporated from the heat transfer liquid heated in the heating tank condenses on the inner side of the lid to form liquid droplets, the liquid droplets due to this condensation can be caused to flow down along the liquid guiding portion from the inner surface of the lid body into the inner space of the heating tank, preventing the liquid derived from the liquid droplets from reaching outside the heating tank. At the same time, when the liquid droplets head toward the vicinity of the inner side wall of the heating tank, if the inner container is placed in the heating tank, the adhesion of the liquid droplets to the inner container can be suppressed, and the treatment when taking out the inner container from the heating tank can be simplified.

[0160] Further, the heating device according to the disclosure of the present invention, as necessary, the heating tank has an inner wall portion surrounding the inner space and an outer wall portion exposed to the outside, and the bottom, the inner wall portion, and the outer wall portion of the heating tank are integrally formed continuously without gaps.

[0161] According to the disclosure of the present invention in this way, the bottom, the inner wall portion, and the outer wall portion constituting the heating tank are integrally formed continuously without gaps, and no joint of parts occurs in the portion appearing on the surface of the heating tank. Therefore, even if the heat transfer liquid is introduced into the internal space of the heating tank or a liquid such as the heat transfer liquid is applied to the outer surface of the heating tank, a situation where the liquid such as the heat transfer liquid penetrates into the inside from the joint of the parts will not occur, and an adverse effect on the internal parts can be prevented.

[0162] Further, the heating device according to the disclosure of the present invention, as necessary, the heating tank has an inner wall portion surrounding the inner space and an outer wall portion exposed to the outside, and a substrate placement space is provided in a part of the gap between the inner wall portion and the outer wall portion. The substrate has at least an operating circuit for the heating portion and is inserted and fixed in the placement space in a state of being attached to a fixing holder.

[0163] According to the disclosure of the present invention as described above, a part of the gap between the inner wall portion and the outer wall portion in the heating tank is used as the placement space for the substrate. With respect to this placement space, a substrate having an operation circuit for the heating unit is inserted and fixed in a state of being attached to the holder, so that an operation on the operation circuit of the substrate can be performed from the outside through the outer wall portion of the heating tank. As a result, the force applied to the substrate during the heating-related operation is received by the holder, preventing excessive force from being applied to the substrate and enhancing durability.

[0164] Further, the heating device according to the disclosure of the present invention, if necessary, the heating tank has an inner wall portion surrounding the tank inner space and an outer wall portion exposed to the outside, and a part of the gap between the inner wall portion and the outer wall portion is provided with a placement space for the substrate. The substrate has at least a control circuit for the heating unit and is inserted and fixed in the placement space in a state of being attached to a fixing holder. A temperature sensor for measuring the temperature of the heat transfer medium liquid in the tank inner space is provided at a predetermined portion along the inner wall portion in the gap between the inner wall portion and the outer wall portion of the heating tank, and the temperature sensor is connected to the control circuit of the substrate.

[0165] According to the disclosure of the present invention as described above, a part of the gap between the inner wall portion and the outer wall portion in the heating tank is used as the placement space for the substrate. By arranging the temperature sensor connected to the substrate in this placement space along the inner wall portion, the temperature of the heat transfer medium liquid in the heating tank can be appropriately measured by the temperature sensor arranged near the inner wall portion of the heating tank, and the temperature adjustment of the heat transfer medium liquid by the heating of the heating unit can be accurately performed based on the obtained temperature.

[0166] Further, the heating device according to the disclosure of the present invention, if necessary, the heating unit is arranged below the bottom of the heating tank.

[0167] According to the disclosure of the present invention as described above, by disposing a heating part below the bottom facing the inner space of the heating tank so that the heat medium liquid stored in the heating tank can be heated from the bottom side, the heating part is positioned as close as possible to the heat medium liquid accumulated at the bottom of the heating tank and the object to be heated that is heat-transferred from this heat medium liquid, so that the object to be heated can be efficiently heated through the heat medium liquid, and the entire object to be heated can be evenly warmed.

[0168] Moreover, according to the heating device related to the disclosure of the present invention, if necessary, the heating part includes a heating heater part with a linear conductor foil arranged in a predetermined configuration and a temperature detection part for temperature detection with a linear conductor foil arranged in a predetermined configuration, and the heater part and the temperature detection part are arranged in a laminated state.

[0169] According to the disclosure of the present invention as described above, the structure is such that the heating part has a heater part and a temperature detection part in a laminated state, and by overlapping and arranging the heater part having a conductor foil and the temperature detection part also having a conductor foil for detecting its temperature, the heating part can be made thinner, the height of the heating tank incorporating the heating part can be suppressed, and if it is made into a plate-like body with the heater part and the temperature detection part laminated and integrated, it is easy to handle, and miniaturization and cost reduction can also be achieved, and it can be easily arranged in the heating tank. Also, by enabling detection by a temperature detection part positioned immediately adjacent to the temperature of the heater part in the heating state, the temperature of the heater part can be accurately detected by the temperature detection part, and appropriate heating control of the heater part based on the detected temperature can be performed.

[0170] Moreover, according to the heating device related to the disclosure of the present invention, if necessary, among the heater part and the temperature detection part that are laminated, the heater part is disposed in the inner layer part between the layer of the temperature detection part and another layer, while the temperature detection part is disposed on the surface layer.

[0171] According to the disclosure of the present invention as described above, the heater part of the heating part is disposed at the inner layer part in the laminated structure, and the temperature detection part is disposed at the surface layer. By the heater part performing heating from the inner layer side, heat can be transmitted from the inside of the heating part to the outside, warming the entire heating part. At the same time, a heat storage effect is caused by the heater part in the inner layer and the surface layer sandwiching it, and the temperature can be efficiently maintained in the heating part.

[0172] Further, according to the disclosure of the present invention, the heating device, if necessary, has at least two heater parts formed as a meandering pattern in which a linear conductor foil is continuously arranged while being folded back a plurality of times on a thin plate. The continuous direction of the linear conductor foil in at least one heater part and the continuous direction of the linear conductor foil in at least one other heater part are laminated in an arrangement relationship perpendicular to each other.

[0173] According to the disclosure of the present invention as described above, at least two heater parts to be laminated in the heating part are structured to have a similar meandering pattern in which a linear conductor foil is folded back a plurality of times, and the continuous direction of the linear conductor foil in one heater part and the continuous direction of the linear conductor foil in the other heater part are in an arrangement relationship perpendicular to each other. By minimizing the overlap of the linear conductor foils in the heater part and increasing the apparent area of the heat generating part, on the heater part in the laminated state, between the heater parts where the continuous directions of the linear conductor foils are in an arrangement relationship perpendicular to each other, the situation where the heat transfer from the linear conductor foil of one heater part to the outside is obstructed by the overlapping linear conductor foil of the other heater part is less likely to occur. The heat generated by the linear conductor foil of the heater part can be efficiently transmitted to the outside, and heating can be performed from the entire surface of the heating part, enabling efficient heating of the object to be heated.

[0174] Further, according to the disclosure of the present invention, the heating device, if necessary, forms the line width and the interval between the lines in the linear conductor foil forming the temperature detection part to be smaller than those in the linear conductor foil forming the heater part, and makes the length of the linear conductor foil forming the temperature detection part larger than the length of the linear conductor foil forming the heater part.

[0175] According to the disclosure of the present invention as described above, the line width and line spacing of the linear conductor foil of the temperature detection part in the heating part are made smaller than those of the linear conductor foil of the heater part, the number of lines of the linear conductor foil of the temperature detection part per unit area of the heating part is increased, and the linear conductor foil of the temperature detection part is formed relatively longer than the linear conductor foil of the heater part on the same heating part. As a result, the resistance value of the linear conductor foil of the temperature detection part becomes larger, and the change in resistance value accompanying the temperature change also becomes larger. Thus, fine temperature changes can be captured from the change in resistance value, and the detection accuracy of temperature can be improved.

[0176] Further, according to the disclosure of the present invention, the heating device may, if necessary, have a diffusion part having a planar conductor foil with the same size as or larger than the heater part laminated and disposed on the side of the heater part opposite to the side where the temperature detection part exists. The diffusion part is provided in the heating tank facing the tank inner space side.

[0177] According to the disclosure of the present invention as described above, a diffusion part having a planar conductor foil is disposed on the side opposite to the side facing the temperature detection part of the heater part in the heating part. The heating part is provided in the heating tank with the diffusion part facing the tank inner space side where the object to be heated is located. Heat generated in the heater part is transmitted to the heat medium liquid in the tank inner space through the diffusion part. Thus, heat can be diffused over the entire surface of the heating part through the diffusion part having the same size as or larger than the heater part, and heat can be efficiently transmitted from the heating part to the heat medium liquid side.

[0178] Further, according to the disclosure of the present invention, the heating device may, if necessary, be formed by electrically connecting the heating part to a location having the power supply potential or a ground potential in the diffusion part in the heater part.

[0179] According to the disclosure of the present invention as described above, by electrically connecting the diffusion part of the heating part to a location at the power supply potential or the ground potential in the heater part, and making the planar conductor foil of the diffusion part also at the power supply potential or the ground potential, the planar conductor foil of the diffusion part serves as a shield against external noise, static electricity, etc., and prevents the influence of such external noise, static electricity, etc. from reaching the heater part, temperature detection part of the heating part, and further the control circuit through these respectively, enabling them to operate stably and not cause malfunction.

[0180] Moreover, the heating device according to the disclosure of the present invention, as required, is such that the heating part is formed with the thickness of the conductor foil in the diffusion part thinner than the thickness of the conductor foil in the heater part.

[0181] According to the disclosure of the present invention as described above, by making the thickness of the planar conductor foil in the diffusion part of the heating part thinner than the thickness of the linear conductor foil in the heater part, and facilitating the spread of the heat transmitted to a part of the planar conductor foil of the diffusion part to each position of the planar conductor foil, the heat can be quickly transmitted to the entire planar conductor foil of the diffusion part and diffused to the entire surface of the heating part, and the heat can be efficiently transferred from the heating part to the heat medium liquid side.

Example

[0182] In order to verify whether the temperature of the object to be heated in the inner container can be appropriately adjusted when the heating device according to the disclosure of the present invention is actually used, the temperature of the water contained in the heating tank and the inner container was measured in the operating state of the heating device, and based on the obtained measurement results, the performance of the heating device was evaluated.

[0183] As an example of a heating device according to the disclosure of the present invention, regarding a heating device capable of accommodating an inner container with a specified internal volume of 600 ml in a heating tank, water as a heat transfer medium liquid and the inner container were accommodated in the heating tank, and after operating the heating device, the temperature was measured inside and outside the inner container. Tap water was put into the inner container as a pseudo-yogurt material liquid up to the specified amount of 600 ml. Also, the water accommodated in the heating tank together with the inner container was 300 ml of tap water, which reached the specified water level of the heating tank and was in a state of sufficiently contacting the bottom surface and side surface of the inner container. Note that the protrusion arrangement at the bottom of the heating tank in the heating device is the same as that in the first embodiment.

[0184] The temperature measurement was performed by using K thermocouples as temperature sensors respectively arranged in the water in the heating tank near the first temperature sensor provided in the heating device and in the water at the center inside the inner container, and detecting and acquiring the water temperature at each location at predetermined time intervals.

[0185] Such a heating device is started up while being installed in an indoor space where the temperature of the indoor air as the ambient atmosphere is 22°C, the heater part of the heating part is set to the maximum output with a duty ratio of 100% of its output, and heating is started in a continuous heating mode without setting a target temperature for heating. The water in the heating tank with an initial temperature of 19.1°C and the water in the inner container with an initial temperature of 18.9°C were each heated by the transferred heat, and in the situation where the water temperature was changing, the water temperatures at the above two locations were measured every 5 seconds by using a data logger and two K thermocouples connected thereto. A graph plotting the temperature values measured every 5 seconds until about 3 hours had elapsed since the start of the measurement is shown in FIG. 25.

[0186] As shown in FIG. 25, in the heating device of this embodiment, it was confirmed that, with respect to the temperature of the water in the heating tank, the temperature of the water in the inner container, which was initially lower, increased at a greater rate over time and eventually exceeded the temperature of the water in the heating tank. One of the reasons is that as the temperature of the water rises and a temperature difference with the surrounding indoor air occurs, the rate of heat escaping from the water in the heating tank to the indoor air outside the heating device through the bottom and the inner wall of the heating tank in contact with the water increases, causing the rate of temperature rise to slow down. Conversely, for the water inside the inner container, since the inner container is separated from the bottom of the heating tank by the protrusions and is also separated from the inner wall of the heating tank, while the water inside the inner container can receive heat from the heated and convecting water in each part of the heating tank, heat is not transmitted to the bottom or the inner wall of the heating tank and escapes. As a result, the state where the heat entering the inner container is greater than the heat escaping from the outside of the inner container continues, and it becomes difficult to reduce the rate of temperature rise of the water inside the inner container.

[0187] From the above measurement results, in the heating device according to the disclosure of the present invention, by supporting the inner container with protrusions in the heating tank and allowing the heated water to flow between the lower surface of the inner container and the bottom of the heating tank, while maintaining the inflow of heat to the inner container, the outflow of heat can be suppressed, and heating can be performed efficiently. In addition, since heat is mainly transmitted to the inner container through the water in the heating tank, sudden changes in the temperature inside the inner container can be prevented, and deterioration of the object to be heated inside the inner container can be suppressed. From these, it is clear that the heating device according to the present invention can appropriately heat and keep warm the object to be heated inside the inner container.

Explanation of Reference Numerals

[0188] 1 Heating device 10 Heating tank 10a Tank inner space 10b Drainage part 10c Guide part 11 Bottom 12 Inner wall part 12a Protrusion 13 Outer wall part 14 Lower lid 15 Protrusion 15a, 15b Protrusions 15c, 15d Protrusions 16 USB terminals 17 Protrusion 19 Holder 20 Cover part 21 Liquid guiding part 30 Inner container 40 Heating part 41, 42 Heater parts 43 Temperature detection part 44 Diffusion part 46 Insulation layer 47 Adhesive layer 48 Protective film 51, 52 Temperature sensors 60 Control part 80 Water 90, 91 Objects to be heated

Claims

1. An inner container capable of accommodating a predetermined object to be heated therein, a heating tank capable of accommodating the inner container and a predetermined heat medium liquid in a tank inner space, and a heating unit capable of heating the heat medium liquid accommodated in the tank inner space of the heating tank, wherein a plurality of protrusions protruding into the tank inner space are formed on the bottom of the heating tank, at least a part of the plurality of protrusions contacts the lower surface of the inner container accommodated in the heating tank to support the inner container, and the heat medium liquid can flow between the bottom of the heating tank and the lower surface of the inner container, and the heat medium liquid has a predetermined storage capacity such that it can contact the side surface of the inner container in the tank inner space of the heating tank is a feature of the heating device.

2. A heating tank capable of accommodating a predetermined object to be heated and a predetermined heat medium liquid in a tank inner space, a heating unit capable of heating the heat medium liquid accommodated in the tank inner space of the heating tank, a temperature sensor provided along an inner wall facing the tank inner space of the heating tank for detecting the temperature of the heat medium liquid, and a control unit for controlling the heating unit based on the temperature detected by the temperature sensor, wherein a plurality of protrusions protruding into the tank inner space are formed on the bottom of the heating tank, and the protrusions are provided in an arrangement in which a plurality of protrusions arranged linearly are further arranged in a plurality of rows in parallel in a direction perpendicular to the longitudinal direction of the heating tank on the inner wall on the side where the temperature sensor exists in the heating tank is a feature of the heating device.

3. In the heating device according to claim 1, the heating tank is formed in an upper surface open box shape that is substantially rectangular in plan view, and the protrusions are provided in an arrangement in which a plurality of protrusions arranged linearly in a direction perpendicular to the longitudinal direction of the heating tank are further arranged in a plurality of rows in parallel in the longitudinal direction of the heating tank on the bottom of the heating tank is a feature of the heating device.

4. In the heating device according to claim 2 or 3, the protrusions are arranged in a staggered state in the longitudinal direction of the heating tank is a feature of the heating device.

5. In the heating device according to claim 1, it is provided with a temperature sensor arranged along the inner wall of the heating tank for measuring the temperature of the heat medium liquid, and the protrusions are arranged in a linear arrangement of a plurality in a direction toward the inner wall where the temperature sensor exists is a feature of the heating device.

6. In the heating device according to claim 1 or 2, the protrusions include at least a first protrusion having a predetermined height and a second protrusion having a height lower than that of the first protrusion is a feature of the heating device.

7. In the heating device according to claim 6, the protrusion is configured such that the height around the central bottom portion of the heating tank is greater than the height at the center of the bottom of the heating tank A heating device characterized by the above. **Claim 8** In the heating device according to claim 7, the protrusion is configured such that the size of the base end portion of the protrusion around the central bottom portion of the heating tank is greater than the size of the base end portion of the protrusion at the center of the bottom of the heating tank A heating device characterized by the above. **Claim 9** In the heating device according to claim 1 or 2, the protrusion is formed in a tapered shape in which the size of the tip end portion of the protrusion is smaller than the size of the base end portion of the protrusion A heating device characterized by the above. **Claim 10** In the heating device according to claim 1 or 2, the protrusion is configured such that the arrangement density around the central bottom portion of the heating tank is greater than the arrangement density at the center of the bottom of the heating tank A heating device characterized by the above. **Claim 11** In the heating device according to claim 1 or 2, a temperature sensor for measuring the ambient temperature around the heating tank is provided along the outer wall facing the external space of the heating tank A heating device characterized by the above. **Claim 12** In the heating device according to claim 11, the heating unit is capable of increasing or decreasing the heating output by PWM control based on the ambient temperature around the heating tank detected by the temperature sensor, and the adjustment is performed such that the duty ratio of the output is decreased as the ambient temperature is higher, and the duty ratio of the output is increased as the ambient temperature is lower A heating device characterized by the above. **Claim 13** In the heating device according to claim 1 or 2, it is provided with a lid portion that can cover and close the upper opening of the heating tank A heating device characterized by the above. **Claim 14** In the heating device according to claim 13, a guide portion, which is an inclined surface that slopes downward toward the inner space of the tank, is formed at a predetermined portion facing the lid portion in a closed state where the lid portion covers the upper opening of the heating tank at the upper part of the heating tank A heating device characterized by the above. **Claim 15** In the heating device according to claim 13, a liquid guiding portion is formed on the inner side portion of the lid portion facing the inner space of the heating tank in a closed state where the lid portion covers the upper opening of the heating tank, and the liquid guiding portion guides the droplets of the heat medium liquid adhering to the lid portion toward the inner space of the heating tank near the inner wall of the heating tank A heating device characterized by the above. **Claim 16** In the heating device according to claim 1 or 2, The heating tank has an inner wall portion surrounding the space inside the tank and an outer wall portion exposed to the outside, and the bottom, the inner wall portion, and the outer wall portion of the heating tank are integrally continuous without gaps. A heating device characterized by the above.

17. In the heating device according to claim 1 or 2 above, The heating tank has an inner wall portion surrounding the space inside the tank and an outer wall portion exposed to the outside, and a placement space for the substrate is provided in a part of the gap between the inner wall portion and the outer wall portion. The substrate has at least an operation circuit for the heating unit, and is inserted and fixed in the placement space in a state of being attached to a fixing holder. A heating device characterized by the above.

18. In the heating device according to claim 1 above, The heating tank has an inner wall portion surrounding the space inside the tank and an outer wall portion exposed to the outside, and a placement space for the substrate is provided in a part of the gap between the inner wall portion and the outer wall portion. The substrate has at least a control circuit for the heating unit, and is inserted and fixed in the placement space in a state of being attached to a fixing holder. A temperature sensor for measuring the temperature of the heat transfer liquid in the tank space is provided at a predetermined position along the inner wall portion in the gap between the inner wall portion and the outer wall portion of the heating tank, and the temperature sensor is connected to the control circuit of the substrate. A heating device characterized by the above.

19. In the heating device according to claim 1 or 2 above, The heating unit is disposed below the bottom of the heating tank. A heating device characterized by the above.

20. In the heating device according to claim 1 or 2 above, The heating unit has a heating heater unit with a linear conductor foil arranged in a predetermined configuration and a temperature detection unit for temperature detection with a linear conductor foil arranged in a predetermined configuration, and the heater unit and the temperature detection unit are arranged in a laminated state. A heating device characterized by the above.

21. In the heating device according to claim 20 above, Among the heater unit and the temperature detection unit that are laminated, the heater unit is disposed at an inner layer portion between the layer of the temperature detection unit and other layers, while the temperature detection unit is disposed at the surface layer. A heating device characterized by the above.

22. In the heating device according to claim 20 above, The heating unit has at least two heater units formed as a meandering pattern in which a linear conductor foil is continuously arranged while being folded back a plurality of times on a thin plate, and the continuous direction of the linear conductor foil in at least one heater unit and the continuous direction of the linear conductor foil in at least one other heater unit are laminated in an arrangement relationship perpendicular to each other. A heating device characterized by the above.

23. In the heating device according to claim 20, The heating unit is formed such that the line width and the interval between the lines of the linear conductor foil forming the temperature detection unit are made smaller than those of the linear conductor foil forming the heater unit, and the length of the linear conductor foil forming the temperature detection unit is made larger than the length of the linear conductor foil forming the heater unit. A heating device characterized by the above.

24. In the heating device according to claim 20, The heating unit is laminated and provided with a diffusion unit having a planar conductor foil having the same size as or larger than the heater unit on the side opposite to the side where the temperature detection unit exists in the heater unit, and the diffusion unit is provided in the heating tank facing the space inside the tank. A heating device characterized by the above.

25. In the heating device according to claim 24, The heating unit is formed by being electrically connected to a location having a power supply potential or a ground potential in the heater unit in the diffusion unit. A heating device characterized by the above.

26. In the heating device according to claim 24, The heating unit is formed such that the thickness of the conductor foil in the diffusion unit is made thinner than the thickness of the conductor foil in the heater unit. A heating device characterized by the above.

Images