Control method of heating element and heater

Abstract

To provide a control method of a heating element and a heater capable of increasing a temperature of an object to be heated to a target temperature accurately in a short time.SOLUTION: A control method of a heating element of the present disclosure includes the steps of: setting a target temperature of an object to be heated; operating the heating element to heat a structure that contacts the object to be heated; detecting a temperature rise speed of the structure at predetermined timing after the start of the heating; calculating a time required for the object to be heated to reach the target temperature from the temperature change; and notifying that the time required to reach the target temperature has elapsed.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a method for controlling a heating element that heats an object and a heater.

Background Art

[0002] Heaters that heat a heated object, such as a retort food (pre-packaged food) in which a heated object, such as cooked food, is stored inside a pouch, using a heating element, are widely used. For example, as a device for heating (warming) retort food, Patent Document 1 below describes a device that sandwiches retort food inserted from an opening between hot plates by pressing it from one side, and warms the retort food by heating the hot plates with a heater having a constant output.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the device of Patent Document 1 above, the ambient temperature inside the device is detected by a temperature sensor, and heating cooking is controlled based on whether or not the ambient temperature has reached a predetermined temperature. However, in the method described above, since the temperature near the surface of the retort food is measured, it may be different from the actual temperature of the contents. Furthermore, it is expected that there will be a difference in the finished temperature depending on the contents of the retort food.

[0005] In consideration of the above problems, an object of the present disclosure is to provide a method for controlling a heating element and a heater that can accurately raise the temperature of a heated object to a target temperature in a short time.

Means for Solving the Problems

[0006] In order to achieve the above object, a method for controlling a heating element according to a first aspect of the present disclosure includes a step of setting a target temperature of an object to be heated, a step of heating a structure in contact with the object to be heated by operating a heating element, a step of detecting a temperature change of the structure at a predetermined timing after the start of the heating, a step of calculating a time for the object to be heated to reach the target temperature from the temperature change, and a step of notifying that the time for reaching the target temperature has elapsed.

[0007] In such a method for controlling a heating element, since the time for the object to be heated to reach the target temperature is calculated from the temperature change of the structure, the object to be heated can be heated to the target temperature with high accuracy in a short time.

[0008] A method for controlling a heating element according to a second aspect of the present disclosure is the method for controlling a heating element according to the first aspect of the present disclosure, wherein the step of calculating the time for the object to be heated to reach the target temperature from the heating rate applies a virtual thermal circuit to a heater including the heating element, and calculates the time for the object to be heated to reach the target temperature using the thermal circuit from the detected heating rate.

[0009] In such a method for controlling a heating element, the time for the object to be heated to reach the target temperature can be accurately calculated.

[0010] A method for controlling a heating element according to a third aspect of the present disclosure includes a step of setting a target temperature of an object to be heated, a step of heating a structure in contact with the object to be heated by operating a heating element, a step of detecting a temperature change of the structure at a predetermined timing after the start of the heating, a step of calculating a reaching temperature of the structure higher than the target temperature and a time for the object to be heated to reach the target temperature from the temperature change, a step of detecting whether the temperature of the structure has reached the reaching temperature, a step of stopping the heating of the heating element when it is detected that the temperature of the structure has reached the reaching temperature, and a step of notifying that the time for reaching the target temperature has elapsed.

[0011] In such a method for controlling a heating element, the object to be heated can be heated to the target temperature without overshooting the target temperature in a short time.

[0012] In the method for controlling a heating element according to the fourth aspect of the present disclosure, in the method for controlling a heating element according to any one of the first to third aspects of the present disclosure, the predetermined timing is the timing at which the change rate of the temperature increase rate per unit time is within 3%, the timing at which the elapsed time from the preset start of heating has elapsed, or the timing at which the structure has reached a preset temperature.

[0013] In such a method for controlling a heating element, since the temperature change of the structure can be accurately specified in order to detect the temperature change after the temperature increase rate has stabilized.

[0014] In the method for controlling a heating element according to the fifth aspect of the present disclosure, in the method for controlling a heating element according to any one of the first to fourth aspects of the present disclosure, the object to be heated contains a liquid, and the heating element is controlled to set the temperature of the liquid to the target temperature.

[0015] In such a method for controlling a heating element, even if a liquid is contained in the object to be heated, the content of the object to be heated is not excessively heated, so that it can be safely heated.

[0016] In the method for controlling a heating element according to the sixth aspect of the present disclosure, in the method for controlling a heating element according to any one of the third to fifth aspects of the present disclosure, the step of calculating the time for the object to be heated to reach the target temperature from the temperature increase rate applies a virtual thermal circuit to the heater including the heating element, and calculates the time for the object to be heated to reach the target temperature using the thermal circuit from the detected temperature increase rate.

[0017] In such a method for controlling a heating element, the time for the object to be heated to reach the target temperature can be accurately calculated.

[0018] The method for controlling a heating element according to the seventh aspect of the present disclosure includes a step of setting a target temperature of an object to be heated, a step of heating a structure in contact with the object to be heated by operating a heating element, a step of detecting a temperature rise of the structure at a predetermined timing after the start of the heating, a step of calculating a time for the object to be heated to reach the target temperature from the temperature rise rate, a step of calculating a heating time for performing the heating from the temperature rise, a step of detecting whether the heating time has elapsed, a step of stopping the heating of the heating element when it is detected that the heating time has elapsed, and a step of notifying that the time for reaching the target temperature has elapsed.

[0019] In such a method for controlling a heating element, the object to be heated can be heated up to the target temperature without overshooting the target temperature in a short time.

[0020] The method for controlling a heating element according to the eighth aspect of the present disclosure is the method for controlling a heating element according to the seventh aspect of the present disclosure, wherein the step of calculating a time for the object to be heated to reach the target temperature from the temperature rise rate applies a virtual thermal circuit to a heater including the heating element, and calculates a time for the object to be heated to reach the target temperature using the thermal circuit from the detected temperature rise rate.

[0021] In such a method for controlling a heating element, the time for the object to be heated to reach the target temperature can be accurately calculated.

[0022] The method for controlling a heating element according to the ninth aspect of the present disclosure includes a step of setting a target temperature of an object to be heated, a step of heating a structure in contact with the object to be heated by operating a heating element, a step of detecting a temperature increase rate of the structure at a predetermined timing after starting the heating, a step of calculating a time for the object to be heated to reach the target temperature from the temperature increase rate, a step of detecting whether the temperature of the structure has reached a predetermined upper limit temperature higher than the target temperature, a step of controlling the heating element to maintain the upper limit temperature when it is detected that the temperature of the structure has reached the upper limit temperature, and a step of notifying that the time for reaching the target temperature has elapsed.

[0023] In such a method for controlling a heating element, the temperature of the object to be heated can be increased to the target temperature in a short time without overheating the object to be heated.

[0024] The method for controlling a heating element according to the tenth aspect of the present disclosure is the method for controlling a heating element according to the ninth aspect of the present disclosure, wherein the step of calculating the time for the object to be heated to reach the target temperature from the temperature increase rate applies a virtual thermal circuit to a heater including the heating element, and calculates the time for the object to be heated to reach the target temperature using the thermal circuit from the detected temperature increase rate.

[0025] In such a method for controlling a heating element, the time for the object to be heated to reach the target temperature can be accurately calculated.

[0026] The method for controlling a heating element according to the eleventh aspect of the present disclosure includes a step of setting a target temperature of an object to be heated, a step of heating a structure in contact with the object to be heated by operating a heating element, a step of stopping the heating at a predetermined timing after starting the heating, a step of detecting a temperature change of the structure after stopping the heating, a step of calculating a time for the object to be heated to reach the target temperature from the temperature change, a step of restarting the heating of the structure by operating the heating element, a step of detecting whether the temperature of the structure has reached a predetermined upper limit temperature higher than the target temperature, a step of controlling the heating element to maintain the upper limit temperature when it is detected that the temperature of the structure has reached the upper limit temperature, and a step of notifying that the time for reaching the target temperature has elapsed.

[0027] In such a method for controlling a heating element, it is possible to raise the temperature of the object to be heated to the target temperature in a short time without overheating the object to be heated. Further, the calculation of the time for reaching the target temperature can be performed with high accuracy.

[0028] The method for controlling a heating element according to the twelfth aspect of the present disclosure is the method for controlling a heating element according to the eleventh aspect of the present disclosure, wherein the step of calculating the time for the object to be heated to reach the target temperature from the temperature change applies a virtual thermal circuit to a heater including the heating element, and calculates the time for the object to be heated to reach the target temperature using the thermal circuit from the detected temperature change.

[0029] In such a method for controlling a heating element, the time for the object to be heated to reach the target temperature can be accurately calculated.

[0030] The heater according to the thirteenth aspect of the present disclosure includes an installation part where an object to be heated is disposed, a structure in contact with the object to be heated disposed in the installation part, a heating element that heats the structure, a temperature detection part that detects the temperature of the structure, and a control part that performs each step of the method for controlling a heating element according to any one of the first to twelfth aspects based on the detection result of the temperature detection part.

[0031] In such a heater, the object to be heated can be heated to the target temperature without overshooting the target temperature in a short time.

[0032] The heater according to the 14th aspect of the present disclosure is the heater according to the 13th aspect of the present disclosure, wherein the installation part is provided between a pair of the structures facing each other with a predetermined interval therebetween, and the heating element is provided on at least one of the pair of structures.

[0033] In such a heater, since the object to be heated installed in the installation part is heated while being sandwiched between a pair of structures, a sufficient contact area between the structure and the object to be heated can be secured, and the object to be heated can be heated evenly.

Advantages of the Invention

[0034] According to the method for controlling the heating element and the heater of the present disclosure, it is possible to accurately raise the temperature of the object to be heated to the target temperature in a short time.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying Out the Invention

[0036] Hereinafter, each embodiment for carrying out the present disclosure will be described with reference to the drawings. In the following, the scope necessary for the description for achieving the object of the present disclosure is schematically shown, and mainly the scope necessary for the description of the corresponding part of the present disclosure will be described, and the parts where the description is omitted shall be based on known techniques.

[0037] <First Embodiment> FIG. 1 is a schematic perspective view showing an example of a heater according to a first embodiment of the present disclosure. Further, FIG. 2 is an exploded perspective view showing the state in which the heater shown in FIG. 1 is disassembled. The heater 1 according to the first embodiment of the present disclosure may be capable of heating (warming) a retort food PF (see FIG. 3) as an example of an object to be heated. In the following, the direction indicated by the arrow X shown in FIG. 1 will be defined as the front-rear direction, and similarly, the direction indicated by the arrow Y will be defined as the left-right direction, and the direction indicated by the arrow Z will be defined as the up-down direction for the description.

[0038] As the retort food PF heated by the heater 1 according to the present embodiment, for example, it may include a pouch P (see FIG. 3) containing a liquid inside, but its size and contents are not particularly limited. Further, as the pouch P, for example, a packaging material in which a film made of a synthetic resin, a metal foil (for example, an aluminum foil), etc. are laminated may be sealed around to provide a space for enclosing a food or the like containing a liquid inside. Further, this pouch P may be a self-standing type or a non-self-standing type.

[0039] As shown in FIGS. 1 and 2, the heater 1 may at least include a pair of wall portions 10 and 20 having a rectangular parallelepiped appearance, which are arranged to face each other at a predetermined interval. An installation portion 30 for arranging the retort food PF as an object to be heated is provided between the pair of wall portions 10 and 20. The pair of wall portions 10 and 20 may be arranged to face each other via the installation portion 30, and more preferably, may be arranged to be substantially parallel. Hereinafter, the one located on the left side of the installation portion 30 when the heater 1 is viewed from the front will be referred to as the first wall portion 10, and the one located on the right side of the installation portion 30 will be referred to as the second wall portion 20, respectively. Note that the aforementioned "rectangular parallelepiped shape" is not limited to the case where all corners are right angles, but includes those in which some of its surfaces are inclined or some of its corners are chamfered.

[0040] As shown particularly in FIG. 2, the first wall portion 10 may include a first wall portion main body 11 and a first heating portion 12. Among these, the first wall portion main body 11 accommodates at least a part of the first heating portion 12 and may be formed of a synthetic resin or the like. The first wall portion main body 11 of the present embodiment may constitute the housing of the heater 1 together with the second wall portion main body 21, the front housing 31, the rear housing 32, and the bottom housing 33, which will be described later. Further, the first wall portion main body 11 can be configured as a plate-like body bent so as to cover, for example, the upper portion and the left side surface of the first heating portion 12.

[0041] The first heating portion 12 may be configured to heat the retort food PF disposed in the installation portion 30, at least a part of the periphery of which other than the portion facing the installation portion 30 is at least partially covered by the first wall portion main body 11. The first heating portion 12 includes at least a first structure 13 capable of contacting the retort food PF disposed in the installation portion 30 and a first heating element 14 capable of heating the first structure 13. The first structure 13 and the second structure 23, which will be described later, correspond to an example of the structure in the present embodiment, and the first heating element 14 and the second heating element 24, which will be described later, correspond to an example of the heating element in the present embodiment.

[0042] The first structure 13 functions as a heat transfer body that transfers heat from the first heating element 14 to the retort food PF, and can be configured as a plate-like body made of a material having a high thermal conductivity, such as iron, aluminum, or an alloy thereof. The surface of the first structure 13 facing the installation portion 30 functions as a heating surface. Further, a fixing piece 13A fixed to a first cover member 15, which will be described later, may stand on the outer periphery of the first structure 13 on the back surface side (that is, in the leftward direction in FIG. 2).

[0043] The first heating element 14 can be composed of a rectangular heater having the same shape as the first structure 13. For this first heating element 14, for example, a polyimide heater, a rubber heater with a nichrome wire arranged inside, etc. can be adopted. Further, the first heating element 14 may be provided so as to be in contact with or close to the back surface (the left surface in FIG. 2) of the first structure 13. The heat generated from the first heating element 14 by energization is transmitted to the retort food PF inserted into the installation part 30 through the first structure 13, or more specifically, the content including the liquid enclosed in the pouch P.

[0044] In addition, the first heating part 12 may include a first cover member 15 that supports the first structure 13 and the first heating element 14. This first cover member 15 may be a member capable of supporting the first structure 13 and the first heating element 14 in a state of being in contact with them, and can be composed of a rectangular member. This first cover member 15 can be fixed to the fixing piece 13A of the first structure 13, whereby the relative positions of the first heating element 14 and the first structure 13 can be fixed. For the first cover member 15, a heat-resistant material, for example, mica or a heat-resistant resin can be used.

[0045] The second wall portion 20 may be arranged symmetrically with the first wall portion 10 with the installation portion 30 interposed therebetween, and its specific configuration can be the same as that of the first wall portion 10. That is, this second wall portion 20 may include a second wall portion main body 21 and a second heating portion 22. Among these, the second wall portion main body 21 can accommodate at least a part of the second heating portion 22, and may be formed of a synthetic resin or the like. The second wall portion main body 21 may also constitute the housing of the heater 1 together with the front housing 31 and the rear housing 32, similar to the first wall portion main body 11. Further, this second wall portion main body 21 can be composed of, for example, a plate-like body bent so as to cover the upper part and the left side surface of the second heating portion 22.

[0046] The second heating unit 22 includes a second structure 23 having fixing pieces 23A on its outer periphery and whose surface contacts the retort food PF housed in the installation part 30, and a second heating element 24 provided on the back side of the second structure 23 for heating the second structure 23. Further, this second heating unit 22 can further include a second cover member 25 attached to the back side of the second heating element 24 for supporting the second structure 23 and the second heating element 24. Note that the detailed structures and the like of the respective components of the second heating unit 22 described above shall be applied with the content described in the first heating unit 12, and the description thereof will be omitted here.

[0047] According to the above-described configuration, the installation part 30 is provided between the first and second structures 13 and 23 facing each other with a predetermined interval therebetween. Further, on the surfaces of the first and second structures 13 and 23 on the side opposite to the installation part 30, the first and second heating elements 14 and 24 are respectively disposed, but only one of these heating elements can also be used.

[0048] Between the first wall part main body 11 of the first wall part 10 and the first heating unit 12, and between the second wall part main body 21 of the second wall part 20 and the second heating unit 22, first and second biasing members 16 and 26 for biasing the first and second heating units 12 and 22 toward the installation part 30 side may be disposed. Specifically, the first biasing member 16 biases the first structure 13 in a direction approaching the second heating surface of the second wall part 20, and the second biasing member 26 biases the second structure 23 in a direction approaching the first heating surface of the first wall part 10. As the first and second biasing members 16 and 26, various biasing means such as coil springs can be adopted. The first and second biasing members 16 and 26 can be disposed such that one end thereof contacts an inner surface of the first and second wall part main bodies 11 and 21, and the other end thereof contacts appropriate positions on the back surfaces of the first and second heating units 12 and 22, that is, the back surfaces of the first and second cover members 15 and 25.

[0049] FIG. 3 is an explanatory diagram showing an example of the operating state when inserting a retort food into the heater shown in FIG. 1 from above. FIG. 3(A) shows the state before the retort food is inserted into the accommodation space, and FIG. 3(B) shows the state after the retort food is inserted into the accommodation space. By including the above-described configuration in the first and second biasing members 16 and 26, the first and second heating portions 12 and 22 are always biased toward the installation portion 30 side. The first and second heating portions 12 and 22 biased toward the installation portion 30 side in this way may protrude toward the installation portion 30 side by a predetermined length with respect to the end faces 11A and 21A on the installation portion 30 side of the first and second wall body portions 11 and 21 before the retort food PF is accommodated. As shown in FIG. 3(A), the protruding length W1 of each of the first and second heating portions 12 and 22 may be, for example, 3 to 6 mm, preferably 4 to 5 mm, and more preferably about 4.5 mm. The first and second heating portions 12 and 22 can move in a direction away from each other against the biasing force of the first and second biasing members 16 and 26 by the amount of the protruding length W1. Instead of adopting the first and second biasing members 16 and 26, the first and second structures 13 and 23 may be fixed to the first and second wall body portions 11 and 22.

[0050] The width W2 of the installation portion 30 in the left-right direction may be appropriately adjusted according to the general width of the retort food PF or the like. Specifically, the width W2 of the installation portion 30 can be appropriately adjusted between 17 and 27 mm. For a specific example, when the width W2 of the installation portion 30 is set to 22 mm and the protruding length W1 of each of the first and second heating portions 12 and 22 described above is 4.5 mm, the distance between the first and second structures 13 and 23 is at least 13 mm and at most 22 mm. As described above, by adjusting the distance between the first and second structures 13 and 23 to 13 to 22 mm, at least the retort food PF having a wall thickness W3 of 13 to 22 mm can be surely sandwiched between the first and second structures 13 and 23 and heated.

[0051] Further, the heater 1 according to the present embodiment includes temperature detection units 17 and 27 capable of detecting the temperature of at least one of the first and second structures 13 and 23. In the present embodiment, as shown in FIG. 2, the first temperature detection unit 17 and the second temperature detection unit 27 for detecting the temperatures of the first and second structures 13 and 23 are provided on both the first wall portion 10 and the second wall portion 20, respectively, as an example.

[0052] The first and second temperature detection units 17 and 27 can be configured by, for example, contact-type temperature sensors. The first and second temperature detection units 17 and 27 may be attached to sensor attachment portions 15M and 25M provided at substantially central portions in the vertical and front-rear directions of the first and second cover members 15 and 25. Further, the detection surfaces 17A and 27A of the first and second temperature detection units 17 and 27 are preferably in contact with the back surface opposite to the surface that functions as the first heating surface of the first structure (also referred to as a "heating plate") 13, and the back surface opposite to the surface that functions as the second heating surface of the second structure 23. Further, the detection surfaces 17A and 27A of the temperature detection units 17 and 27 according to the present embodiment are in contact with the back surfaces of the first and second structures 13 and 23 through through-holes 14H, 24H, 15H, and 25H provided in the first and second heating elements 14 and 24 and the first and second cover members 15 and 25, respectively. Note that since the sensor attachment portion 15M and the through-hole 15H are in positions hidden by other members and cannot be visually recognized in FIG. 2, the illustration of the reference numerals is omitted.

[0053] In addition to the first and second wall portions 10 and 20 described above, the heater 1 according to the present embodiment may further include three housings 31, 32, and 33 that cover the front portion, the rear portion, and the bottom portion of the first and second wall portions 10 and 20. Among these, the front housing 31 and the rear housing 32 can be formed of members made of, for example, the same material as the first and second wall body portions 11 and 21, which are formed in a substantially U shape in a front view as shown in FIG. 2. The front openings 31A and the rear openings 32A that are U-shaped openings of the front housing 31 and the rear housing 32 are preferably adjusted in advance to a size that communicates with the installation portion 30 when attached to the first and second wall portions 10 and 20.

[0054] The bottom housing 33 is disposed on the bottom surface of the heater 1 and can be formed of a member made of the same material as, for example, the first and second wall body main parts 11 and 21, with a plurality (for example, four) of legs 33A attached to each corner. A main control board 41 that constitutes a control unit 40 for controlling the first and second heating elements 14 and 24 may be disposed on the bottom housing 33 based on the detection results of the first and second temperature detection units 17 and 27.

[0055] Also, a partition plate 34 (see FIG. 3) for partitioning the main control board 41 and the installation part 30 may be disposed above the main control board 41. This partition plate 34 can be formed of a plate-like body extending substantially parallel to the bottom housing 33, and its upper surface can function as the bottom surface of the installation part 30. Therefore, it is preferable that the upper surface of this partition plate 34 is located in the same plane as the lower surfaces of the front opening 31A and the rear opening 32A, as it is difficult for dust or the like to accumulate between these members and the cleaning work becomes easy. Note that the illustration of the partition plate 34 is omitted in FIG. 2.

[0056] The control unit 40 included in the heater 1 according to the present embodiment is capable of controlling the first and second heating elements 14 and 24 and may mainly include the main control board 41. This main control board 41 may be electrically connected to the first and second heating elements 14 and 24. In this regard, the main control board 41 may also be electrically connected to the first and second temperature detection units 17 and 27. To supply power to the first and second heating elements 14 and 24, the main control board 41 may be connected to a power cord 42 having a power plug at its tip. Also, various electronic components such as capacitors and resistors used when performing various controls may be mounted on the main control board 41. The control method of the heating element that can be implemented by the control unit 40 will be described later.

[0057] On the right surface of the front housing 31, there may be included a switch for operating the heater 1, for example, a start switch 43 capable of switching the ON / OFF of the heater 1. This start switch 43 may be mounted on a switch mounting board 45 as part of a control unit 40 disposed on the back surface of the front housing 31, and this switch mounting board 44 may be connected to the main control board 41.

[0058] Also, the heater 1 according to the present embodiment can include a temperature setting switch 50 as an input unit capable of inputting a target temperature T0 when heating the retort food PF. This temperature setting switch 50 may be mounted on the switch mounting board 44 in the same manner as the start switch 43, and may be electrically connected to the main control board 41.

[0059] The temperature setting switch 50 in the present embodiment can be configured to be able to select the target temperature of the retort food PF step by step. Specifically, by pressing the temperature setting switch 50, it is possible to select a desired temperature from predetermined target temperatures (for example, 100°C, 85°C, 70°C, 55°C, etc.). Note that the number and temperature of the predetermined target temperatures can be changed as appropriate.

[0060] In relation to the above, on the upper part of the temperature setting switch 50, there may be provided a display unit 51 capable of displaying at least the target temperature selected by operating the above-described temperature setting switch 50. As the display unit 51 according to the present embodiment, an example can be a configuration including a number (for example, 4) of LED lamps corresponding to selectable target temperatures. Note that, in addition to the LED lamps, other display means such as a liquid crystal monitor can be adopted for this display unit 51. By providing this display unit 51, a user or the like can easily grasp the selected target temperature at a glance.

[0061] In this embodiment, the start switch 43 and the temperature setting switch 50 are exemplified as the switches for operating the heater, but the switches of the present disclosure are not limited to only these two. For example, in order to more accurately heat the retort food PF, a switch capable of inputting the capacity (weight) of the retort food RF or a switch capable of inputting the contents of the retort food PF (for example, soup, curry, water) can also be adopted.

[0062] Also, in order to notify the user of the operating state of the heater 1 and the temperatures of the first and second structures 13 and 23, a lamp 53 may be disposed at an appropriate position on the housing of the heater 1. The lamp 53 according to this embodiment may have a function as a warning lamp that lights up when the first and second structures 13 and 23 are at a high temperature.

[0063] The lamp 53 of this embodiment is disposed so as to extend from the front end of the upper surface of the second wall portion 20 to the upper end portion on the second wall portion 20 side of the front housing 31 in order to improve its visibility. When the lamp 53 is disposed as described above, the lamp 53 can be visually recognized from either the upper surface side or the front surface side of the heater 1. Therefore, for example, when the lamp 53 is lit to notify that the first and second structures 13 and 23 are at a high temperature, it is almost impossible for the user to overlook the lighting state of the lamp 47. Therefore, it is possible to suppress an accident in which the user accidentally touches the high-temperature first and second structures 13 and 23.

[0064] In this embodiment, the case where one lamp 53 is disposed at the front end portion of the second wall portion 20 is exemplified, but the arrangement, shape, number, etc. of the lamp 53 can be appropriately changed as long as the above-described effects can be expected. Specifically, the lamp 53 may be disposed at at least one location on the outer edge portion of the upper surface of the first wall portion 10 or the second wall portion 20 so as to extend from the upper surface of the first wall portion 10 or the second wall portion 20 to another surface adjacent to the upper surface of the first wall portion 10 or the second wall portion 20.

[0065] As shown in FIG. 1, for the heater 1 including the above-described series of configurations, among the outer periphery of the rectangular installation portion 30 sandwiched between the first and second wall portions 10 and 20, three surfaces excluding the bottom surface are open to the outside of the heater 1. Therefore, when heating the retort food PF using the heater 1, the retort food PF can be inserted into the installation portion 30 of the heater 1 by inserting it through any of the above three openings.

[0066] Also, when heating the retort food PF as an object to be heated using the heater 1 including the above-described series of configurations, first, as shown in FIG. 3(A), the retort food PF is moved in the direction of the arrow in the figure, and the retort food PF is inserted into the installation portion 30 from the upper opening of the heater 1. Here, when the retort food PF is inserted into the installation portion 30, the first and second structures 13 and 14 move so as to be pushed apart in the left-right direction against the biasing forces of the first and second biasing members 16 and 26 by the pouch P of the retort food PF. When the insertion of the retort food PF into the installation portion 30 is completed, the first and second structures 13 and 23 are pressed against the pouch P by the biasing forces from the first and second biasing members 16 and 26 as shown in FIG. 3(B).

[0067] After the state shown in FIG. 3(B) is set, when the user operates the start switch 43, the control unit 40 executes control of the first and second heating elements 14 and 24. Hereinafter, the control method of the heating element according to the present embodiment will be described. The control method of the heating element according to the present embodiment can be realized, for example, by the control unit 40 of the heater 1 described above. Therefore, the control method of the heating element according to the present embodiment can be provided in the form of a program such as software including a command for causing a computer configured by the main control board 41 to execute a predetermined operation, in the form of a non-temporary recording medium storing this program, or in the form of an application program provided via a network or the like.

[0068] As the retort food PF as the object to be heated has a wide variety of pouch P sizes and contents, the amount of heat and heating time required to reach the target temperature vary. Therefore, for example, when using a device that heats with a constant heater output as described in Patent Document 1 above, if the heater output is increased, there is a risk that the temperature of the contents of the pouch P will become higher than the target temperature depending on the type of retort food PF. Therefore, there is a limit even if you want to increase the heater output and shorten the heating time. In this case, it takes a relatively long time to heat the retort food PF to the target temperature. In the method for controlling the heating element according to the present embodiment, in consideration of the above points, in order to complete heating without overshoot and in a short time according to the heat capacity and size of the retort food PF, the following steps are adopted.

[0069] The method for controlling the heating element according to the present embodiment includes at least a step (S01) of setting a target temperature T0 of the retort food PF, and at least one of the first and second structures 13 and 23 in contact with the retort food PF. A step (S02) of heating by operating at least one of the first and second heating elements 14 and 24, a step (S04) of detecting the temperature increase rate of the first and second structures 13 and 23 at a predetermined timing after starting heating, and a step (S05) of calculating the time t0 when the retort food PF reaches the target temperature T0 from the temperature increase rate, and a step (S09) of notifying that the time t0 when the target temperature T0 is reached has elapsed.

[0070] More specifically, the method for controlling the heating element according to the present embodiment includes a step of setting a target temperature T0 of the retort food PF (S01), a step of heating at least one of the first and second structures 13 and 23 in contact with the retort food PF by operating at least one of the first and second heating elements 14 and 24 (S02), a step of detecting the temperature increase rate of the first and second structures 13 and 23 at a predetermined timing after the start of heating (S04), a step of calculating the reaching temperature Tr of the first and second structures 13 and 23 higher than the target temperature T0 and the time t0 when the retort food PF reaches the target temperature T0 from the temperature increase rate (S05), a step of detecting whether the temperatures of the first and second structures 13 and 23 have reached the reaching temperature Tr (S06), a step of stopping the heating of the first and second heating elements 14 and 24 when it is detected that the temperatures of the first and second structures 13 and 23 have reached the reaching temperature Tr (S07), and a step of notifying that the time t0 when the target temperature T0 is reached has elapsed (S08). Hereinafter, it will be described in more detail mainly with reference to FIGS. 4 and 5.

[0071] FIG. 4 is a flowchart showing an example of the method for controlling the heating element according to the first embodiment of the present disclosure. Further, FIG. 5 is a graph showing an example of the temperature transition of the structure when the method for controlling the heating element shown in FIG. 4 is implemented. In FIG. 5, the solid line graph is the temperature transition of the first and second structures 13 and 23 detected by the first and second temperature detection units 17 and 27, and the broken line graph is the estimated value of the temperature of the content of the retort food PF at the same time point. As shown in FIG. 3(B), when the retort food PF is installed in the installation unit 30 and the start switch 43 is pressed, the control unit 40 next acquires the target temperature T0 (step S01). The target temperature T0 can be set to an arbitrary temperature, for example, by the user operating the temperature setting switch 50.

[0072] When the target temperature T0 is acquired, the control unit 40 supplies power to the first and second heating elements 14 and 24 to start heating the retort food PF. At this time, the control unit 40 operates the first and second heating elements 14 and 24 to raise the temperatures of the first and second structures 13 and 23 and the retort food PF in contact therewith (step S02). During this heating, regardless of the value of the target temperature T0, it can be operated, for example, to be maximized so that the amount of heat generated by the first and second heating elements 14 and 24 increases. As shown in FIG. 5, the temperature of the contents of the retort food PF rises in a manner that lags behind the temperature rise of the first and second structures 13 and 23.

[0073] When heating is started, the control unit 40 detects the temperature changes of the first and second structures 13 and 23. Specifically, in order to measure the temperature increase rate S of the first and second structures 13 and 23, a timer (not shown) is operated to measure the elapsed time since the start of heating, and it is detected whether or not a predetermined time t1 has been reached (step S03). The predetermined time t1 may be set in consideration of the timing at which the temperature increase rates of the first and second structures 13 and 23 become stable after heating starts. In the present embodiment, the timing at which the temperature increase rate becomes stable is defined by detecting the elapse of the predetermined time t1, but the timing at which the temperature increase rate becomes stable can also be defined by other methods. Specifically, the timing at which the change rate of the temperature increase rate per unit time is within 3%, or the timing at which the first and second structures 13 and 23 reach a preset temperature, may be defined as the timing at which the temperature increase rate becomes stable.

[0074] When the elapse of the predetermined time t1 is detected (Yes in step S03), the control unit 40 calculates the temperature increase rate S (step S04). Various methods can be adopted for calculating the temperature increase rate S. For example, the detection results of the first and second temperature detection units 17 and 27 are acquired a plurality of times (for example, 3 times) at equal time intervals (for example, 1-second intervals), and a regression line using the least squares method is calculated from these plurality of detection results, and by referring to this, the temperature increase rate S can be derived.

[0075] The heating rate S derived here is a value correlated with the weight of the retort food PF and its contents. Therefore, by controlling the heating element using this heating rate S, heating can be accurately realized according to the weight and contents of the retort food PF.

[0076] When the heating rate S is calculated, the control unit 40 then calculates the target temperature Tr (step S05). The target temperature Tr is set to a temperature higher than the target temperature T0 and can be calculated, for example, by the following formula (1).

Equation

[0077] Figure 6 is a graph showing an example of the relationship between the heating rate and the target temperature of the structure when the control method of the heating element shown in Figure 4 is implemented. In Figure 6, the relationship between the heating rate S and the target temperature Tr when the target temperatures T0 = 80 °C, 70 °C, 60 °C, and 50 °C are set is shown as an approximate straight line. Note that this approximate straight line can be derived from the values of the heating rate S and the target temperature Tr collected by experiments. As shown in Figure 6, it can be understood that there is a negative correlation between the heating rate S and the target temperature Tr regardless of the target temperature T0.

[0078] Together with the calculation of the target temperature Tr described above, the time (end time) t0 when heating ends is calculated. The end time t0 can be estimated by calculation when the target temperature Tr is specified.

[0079] When the arrival temperature Tr and the end time t0 are calculated, the control unit 40 continues to monitor the detection results of the first and second temperature detection units 17 and 27, and continues heating until it detects that the detected temperature, that is, the temperatures of the first and second structures 13 and 23, have reached the arrival temperature Tr. When it detects that the temperatures of the first and second structures 13 and 23 have reached the arrival temperature Tr (Yes in step S06), the control unit 40 stops the power supply to the first and second heating elements 14 and 24 to stop heating the first and second structures 13 and 23 (step S07).

[0080] Here, it should be particularly noted that the estimated value of the temperature of the contents of the retort food PF when the temperatures of the first and second structures 13 and 23 reach the arrival temperature Tr (point P1 in FIG. 5) is lower than the target temperature T0. The arrival temperature Tr is a temperature set higher than the target temperature T0 and can be, for example, around 100°C. Therefore, if the temperature of the contents of the retort food PF is heated to 100°C or higher, which is the boiling point of water, the pouch P may be damaged due to bumping boiling or the like of the contents of the retort food PF.

[0081] However, in the present embodiment, when the temperature of the contents of the retort food PF is lower than the target temperature T0, the first and second structures 13 and 23 are heated up to the arrival temperature Tr, and then the heating by the first and second heating elements 14 and 24 is stopped at a timing when the retort food PF is not overheated. Therefore, the retort food PF can be heated without generating an overshoot. In addition, the output of the first and second heating elements 14 and 24 during heating can be set large, so that the heating of the retort food PF to the target temperature T0 can be completed in a short time.

[0082] When the heating of the first and second structures 13 and 23 is stopped in step S07, the heat of the first and second structures 13 and 23 heated to the reaching temperature Tr is transferred to the retort food PF in contact with the first and second structures 13 and 23. As a result, the first and second structures 13 and 23 and the retort food PF shift to a thermal equilibrium state. Then, when the first and second temperature detection units 17 and 27 detect that the temperatures of the first and second structures 13 and 23 have reached the target temperature T0, or detect that the elapsed time has reached the end time t0 (Yes in step S08), the control unit 40 notifies the user that the heating of the retort food PF is completed. Specifically, it displays that the retort food PF has been heated to the target temperature T0 (step S09). Various display methods can be assumed. For example, methods such as blinking the display unit 51 or the lamp 53, or lighting up in a specific color can be considered. Also, in addition to the display, sound or the like may be used.

[0083] After notifying the user that the heating is completed, control can be performed such as immediately ending the heating at that point (point P2 in FIG. 5), shifting to temperature holding control for heat preservation and continuing the heating, or ending the heating after performing temperature holding control for a predetermined time (for example, several seconds to several tens of seconds). Here, the temperature holding control is to operate the first and second heating elements 14 and 24 so that the temperatures of the first and second structures 13 and 23 maintain the target temperature T0. As a specific control method for such heat preservation, control (so-called on-off control) that intermittently supplies power to the first and second heating elements 14 and 24 at a specific timing to operate the first and second heating elements 14 and 24 intermittently can be used.

[0084] As described above, according to the heating element control method and the heater 1 according to the present embodiment, by controlling the heating element based on the temperature change of the structure, heating control considering the temperature of the retort food PF can be realized. Further, in the heating element control method according to the present embodiment, at the initial stage of heating, the control time with a large heating amount can be lengthened, and the time required to heat the retort food PF to the target temperature T0 can be shortened. In addition, even when the temperature of the structure reaches the reaching temperature higher than the target temperature T0, the heating is terminated at a timing when the temperature of the content of the retort food PF does not become higher than the target temperature T0, that is, there is no overshoot. Therefore, the retort food PF can be heated to the target temperature T0 in a short time while avoiding an over-temperature state.

[0085] Further, according to the heater 1 according to the present embodiment, the user can simply and accurately heat the retort food PF to the target temperature in a short time by inserting the retort food PF to be heated into the installation portion 30, operating the temperature setting switch 50 to set the target temperature, and pressing the start switch 43. In addition, regardless of the size of the retort food PF, heating that avoids overshoot can be executed, so that damage to the pouch P due to overheating can be substantially eliminated.

[0086] In the above-described embodiment, the user only sets the target temperature T0. However, if information regarding the weight and content of the retort food PF can be input, the accuracy of subsequent processes can be improved.

[0087] Further, in the heating element control method according to the present embodiment described above, although an example is shown in which heating is stopped when the temperatures of the first and second structures 13 and 23 reach the reaching temperature Tr, instead, it may be immediately switched to control for maintaining the temperature at the target temperature T0.

[0088] <Second Embodiment> In the method for controlling the heating element according to the first embodiment described above, the case where the reaching temperature Tr is calculated using the calculated heating rate S and the heating is stopped at the timing when the reaching temperature Tr is reached is exemplified. However, the present disclosure is not limited to this. Therefore, as a second embodiment, a method for controlling the heating element in which the timing of stopping the heating is specified by another method will be described below. The method for controlling the heating element according to the present embodiment can be implemented by the heater 1 described in the first embodiment. In addition, among the methods for controlling the heating element according to the present embodiment, the same steps as those in the method for controlling the heating element according to the first embodiment are denoted by the same reference numerals as those used in the method for controlling the heating element according to the first embodiment, and the description thereof is omitted, and the description will be centered on the steps different from those in the first embodiment.

[0089] The method for controlling the heating element according to the present embodiment includes at least a step (S01) of setting a target temperature T0 of the retort food PF, a step (S02) of raising the temperature by operating at least one of the first and second heating elements 14 and 24 for at least one of the first and second structures 13 and 23 in contact with the retort food PF, a step (S04) of calculating the temperature change of the first and second structures 13 and 23 at a predetermined timing after the start of the temperature rise, a step (S05A) of calculating an end time t0, which is the time for the object to be heated to reach the target temperature T0 from the heating rate, and a heating time tr for performing the temperature rise from the temperature change, a step (S06A) of detecting whether the heating time tr has elapsed, a step (S07) of stopping the temperature rise of the first and second heating elements 14 and 24 when it is detected that the heating time tr has elapsed, and a step (S09) of notifying that the time to reach the target temperature T0 has elapsed. Hereinafter, it will be described in more detail mainly with reference to FIGS. 7 and 8.

[0090] FIG. 7 is a flowchart showing an example of a method for controlling a heating element according to the second embodiment of the present disclosure. FIG. 8 is a graph showing an example of temperature change when the method for controlling the heating element shown in FIG. 7 is implemented. In FIG. 8, the solid line graph shows the temperature change of the first and second structures 13 and 23 detected by the first and second temperature detection units 17 and 27 in the present embodiment, and the broken line graph is an estimated value of the temperature of the contents of the retort food PF at the same time point.

[0091] When the retort food PF is installed in the installation unit 30 and the start switch 43 is pressed, the control unit 40 obtains the target temperature T0 in the same manner as the method for controlling the heating element according to the first embodiment (step S01). Next, the control unit 40 operates the first and second heating elements 14 and 24 to perform heating, detects whether the elapsed time from the start of heating has reached a predetermined time t1, and when the elapse of the predetermined time t1 is detected, calculates the heating rate S corresponding to the temperature change of the first and second structures 13 and 23 (steps S02 to S04).

[0092] When the heating rate S is calculated, the control unit 40 then calculates the end time t0 and the heating time tr (step S05A). First, the heating time tr corresponds to the time for continuing heating and can be calculated, for example, by the following formula (2).

Equation

[0093] FIG. 9 is a graph showing an example of the relationship between the heating rate of the structure and the heating time when the method for controlling the heating element shown in FIG. 7 is implemented. In FIG. 9, the relationship between the heating rate S and the heating time tr when the target temperatures T0 = 80°C, 70°C, 60°C, and 50°C are set is shown by approximate straight lines. Note that this approximate straight line can be derived from the values of the heating rate S and the heating time tr collected through experiments. As shown in FIG. 9, it can be understood that there is also a negative correlation between the heating rate S and the heating time tr regardless of the target temperature T0.

[0094] Along with the calculation of the heating time tr described above, an end time t0 for ending the heating is calculated. The end time t0 can be estimated by calculation when the heating time tr is specified.

[0095] When the heating time tr and the end time t0 are calculated, the control unit 40 continues the heating until it detects that the elapsed time from the start of heating has reached the heating time tr. When it detects that the elapsed time from the start of heating has reached the heating time tr (Yes in step S06A), the control unit 40 stops the power supply to the first and second heating elements 14 and 24, thereby stopping the heating of the first and second structures 13 and 23 (step S07).

[0096] When the heating of the first and second structures 13 and 23 is stopped, the first and second structures 13 and 23 and the retort food PF shift to a thermal equilibrium state. Then, when it detects that the temperatures of the first and second structures 13 and 23 have reached the target temperature T0, or when it detects that the elapsed time has reached the end time t0 (Yes in step S08), the control unit 40 notifies the user that the heating of the retort food PF is completed. Specifically, it displays that the retort food PF has been heated to the target temperature T0 (step S09).

[0097] As described above, also in the method for controlling the heating element according to the present embodiment, since the temperature of the structure can be raised in a short time while suppressing overheating, the same effect as the method for controlling the heating element according to the first embodiment can be expected.

[0098] <Third Embodiment> For example, in the first embodiment described above, the first and second structures 13 and 23 are temporarily heated up to a reaching temperature Tr higher than the target temperature T0, thereby heating the retort food PF to a desired temperature in a short time. On the other hand, for example, when an upper limit temperature Tc is set for the heater 1 due to the relationship such as the heat resistance of the components of the heater 1, the above-described reaching temperature Tr may be such that Tr > Tc. Therefore, hereinafter, as a third embodiment of the present disclosure, an example of a method for controlling a heating element when an upper limit temperature Tc is set for the heater 1 will be described.

[0099] Note that the method for controlling the heating element according to the present embodiment can be implemented by the heater 1 described in the first embodiment. Among the methods for controlling the heating element according to the present embodiment, for the steps similar to those of the method for controlling the heating element according to the first embodiment, the same reference numerals as those used in the method for controlling the heating element according to the first embodiment are assigned and the description thereof is omitted, and hereinafter, the description will be mainly centered on the steps different from those of the first embodiment.

[0100] The method for controlling the heating element according to the present embodiment includes at least a step (S01) of setting a target temperature T0 of the retort food PF, a step (S02) of heating up at least one of the first and second structures 13 and 23 in contact with the retort food PF by operating at least one of the first and second heating elements 14 and 24, a step (S04) of detecting the heating rate of the first and second structures 13 and 23 at a predetermined timing after the start of heating up, a step (S05B) of calculating a time t0 when the retort food PF reaches the target temperature T0 from the heating rate, a step (S06B) of detecting whether the temperature of the first and second structures 13 and 23 has reached a predetermined upper limit temperature Tc higher than the target temperature T0, a step (S07B) of controlling the first and second heating elements 14 and 24 to maintain the upper limit temperature Tc when it is detected that the temperature of the first and second structures 13 and 23 has reached the upper limit temperature Tc, and a step (S09) of notifying that the time for reaching the target temperature T0 has elapsed. The following will be described in more detail mainly with reference to FIGS. 10 and 11.

[0101] FIG. 10 is a flowchart showing an example of a method for manufacturing a heating element according to the third embodiment of the present disclosure. FIG. 11 is a graph showing an example of the temperature change of the structure when the control method of the heating element shown in FIG. 10 is implemented. In FIG. 11, the solid line graph is the temperature change of the first and second structures 13 and 23 detected by the first and second temperature detection units 17 and 27 in the present embodiment, and the broken line graph is the estimated value of the temperature of the contents of the retort food PF at the same time point.

[0102] When the retort food PF is installed in the installation unit 30 and the start switch 43 is pressed, the control unit 40 acquires the target temperature T0 in the same manner as the control method of the heating element according to the first embodiment (step S01). Next, the control unit 40 operates the first and second heating elements 14 and 24 to perform heating, detects whether the elapsed time from the start of heating has reached a predetermined time t1, and when the elapse of the predetermined time t1 is detected, calculates the temperature increase rate S corresponding to the temperature change of the first and second structures 13 and 23 (steps S02 to S04).

[0103] When the temperature increase rate S is calculated, the control unit 40 then calculates the end time t0 for ending the heating (step S05B). The end time t0 can be calculated, for example, by predicting the time required for the first and second structures 13 and 23 to reach the upper limit temperature Tc and the time from when the first and second structures 13 and 23 reach the upper limit temperature Tc until the retort food PF reaches the target temperature T0, based on the performance of the first and second heating elements 14 and 24, the heat capacity of the first and second structures 13 and 23, and the like.

[0104] When the end time t0 is calculated, the control unit 40 continues to monitor the detection results of the first and second temperature detection units 17 and 27, and continues heating until it detects that the detected temperature, that is, the temperatures of the first and second structures 13 and 23, have reached the upper limit temperature Tc. When it detects that the temperatures of the first and second structures 13 and 23 have reached the upper limit temperature Tc (Yes in step S06B), the control unit 40 starts temperature holding control to control the first and second heating elements 14 and 15 so that the temperatures of the first and second structures 13 and 23 are maintained at the upper limit temperature Tc (step S07B). The details of the temperature holding control are as described above. Further, the temperature holding control continues from the time (time t2) when the temperatures of the first and second structures 13 and 23 reach the upper limit temperature Tc until the retort food PF reaches the target temperature T0.

[0105] By the above-described temperature holding control, the retort food PF is continuously heated. When it detects that the elapsed time has reached the end time t0 (Yes in step S08B), the control unit 40 notifies the user that the heating of the retort food PF is completed. Specifically, it displays that the retort food PF has been heated to the target temperature T0 (step S09).

[0106] As described above, also in the method for controlling the heating element according to the present embodiment, since the object to be heated can be heated up in a short time while suppressing overheating, the same effect as the method for controlling the heating element according to the first embodiment can be expected. In addition, when heating the retort food PF, heating exceeding the upper limit temperature Tc of the heater 1 is not performed, so damage to the heater 1 can be avoided.

[0107] <Fourth Embodiment> In the above-described first to third embodiments, the temperature changes of the first and second structures 13 and 23 are specified by calculating the temperature increase rate S after a predetermined time t1 has elapsed since the start of heating. However, the present disclosure is not limited to this. Therefore, below, as a fourth embodiment of the present disclosure, an example of a method for controlling a heating element in which the temperature changes of the first and second structures 13 and 23 are calculated by a different method will be described.

[0108] Note that the method for controlling the heating element according to the present embodiment can be implemented by the heater 1 described in the first embodiment. Also, many steps of the method for controlling the heating element according to the present embodiment can be made common with those of the third embodiment. Therefore, among the steps of the method for controlling the heating element according to the present embodiment, for the steps that are the same as those of the method for controlling the heating element according to the third embodiment, the same reference numerals as those used in the method for controlling the heating element according to the third embodiment are attached and the description thereof is omitted, and the following description will focus on the steps different from those of the third embodiment.

[0109] The method for controlling the heating element according to the present embodiment includes at least a step (S01) of setting a target temperature T0 of the retort food PF, a step (S02) of raising the temperature by operating at least one of the first and second structures 13 and 23 in contact with the retort food PF by operating at least one of the first and second heating elements 14 and 24, a step (S04C1) of stopping the temperature rise at a predetermined timing after starting the temperature rise, a step (S04C2) of detecting a temperature change ΔT of the first and second structures 13 and 23 after stopping the temperature rise, a step (S05C1) of calculating a time t0 when the retort food PF reaches the target temperature T0 from the temperature change ΔT, a step (S05C2) of restarting the temperature rise of the first and second structures 13 and 23 by operating the first and second heating elements 14 and 24, a step (S06B) of detecting whether the temperature of the first and second structures 13 and 23 has reached a predetermined upper limit temperature Tc higher than the target temperature T0, a step (S07B) of controlling the first and second heating elements 14 and 24 so as to maintain the upper limit temperature Tc when it is detected that the temperature of the first and second structures 13 and 23 has reached the upper limit temperature Tc, and a step (S09) of notifying that the time for reaching the target temperature T0 has elapsed. Hereinafter, a more detailed description will be given mainly with reference to FIGS. 12 and 13.

[0110] FIG. 12 is a flowchart showing an example of a method for manufacturing a heating element according to a fourth embodiment of the present disclosure. FIG. 13 is a graph showing an example of the temperature transition of the structure when the control method of the heating element shown in FIG. 12 is implemented. In FIG. 13, the solid-line graph shows the temperature transitions of the first and second structures 13 and 23 detected by the first and second temperature detection units 17 and 27 in the present embodiment, and the dashed-line graph is an estimated value of the temperature of the contents of the retort food PF at the same time point.

[0111] When the retort food PF is installed in the installation unit 30 and the start switch 43 is pressed, the control unit 40 acquires the target temperature T0 (step S01). Next, the control unit 40 operates the first and second heating elements 14 and 24 to start heating (step S02), and detects whether the elapsed time from the start of heating has reached a predetermined time t1 (step S03).

[0112] When it is detected that the predetermined time t1 has elapsed (Yes in step S03), the control unit 40 stops the first and second heating elements 14 and 24 and temporarily stops the temperature rise of the first and second structures 13 and 23 and the retort food PF (step S04C1).

[0113] When the first and second heating elements 14 and 24 stop, the temperatures of the first and second structures 13 and 23 and the retort food PF decrease. Then, the control unit 40 detects the temperature changes of the first and second structures 13 and 23 that decrease with the stop of heating (step S04C2). The temperature change can be specified by calculating an approximate formula from the temperatures detected a plurality of times at predetermined intervals, for example, in the same manner as when calculating the temperature rise rate S. Then, from the detected temperature change ΔT, the time (end time) t0 until the retort food PF reaches the target temperature T0 is calculated (step S05C1).

[0114] When the end time t0 is calculated (time t3), the control unit 40 operates the first and second heating elements 14 and 24 again to resume heating the first and second structures 13 and 23 and the retort food PF (step S05C2). After resuming the heating, the control unit 40 continues to monitor the detection results of the first and second temperature detection units 17 and 27, and continues the heating until it detects that the detected temperature, that is, the temperatures of the first and second structures 13 and 23 have reached the upper limit temperature Tc. When it detects that the temperatures of the first and second structures 13 and 23 have reached the upper limit temperature Tc (Yes in step S06B), the control unit 40 starts temperature holding control to control the first and second heating elements 14 and 15 so that the temperatures of the first and second structures 13 and 23 are maintained at the upper limit temperature Tc (step S07B). Also, the temperature holding control continues from the time (time t2) when the temperatures of the first and second structures 13 and 23 reach the upper limit temperature Tc until the retort food PF reaches the target temperature T0.

[0115] By the above-described temperature holding control, the retort food PF is continuously heated. When it detects that the elapsed time has reached the end time t0 (Yes in step S08B), the control unit 40 notifies the user that the heating of the retort food PF is completed. Specifically, it displays that the retort food PF has been heated to the target temperature T0 (step S09).

[0116] As described above, also in the control method of the heating element according to the present embodiment, since the object to be heated can be heated up in a short time while suppressing overheating, the same effect as the control method of the heating element according to the first embodiment can be expected. In addition, since the temperature change of the structure is calculated with the heating of the heating element stopped, the influence of noise can be suppressed, and the calculation accuracy of the time t0 to reach the target temperature T0 can be improved.

[0117] <Modification Example> The end time t0 calculated in each of the above-described embodiments can also be calculated by applying a virtual thermal circuit to the heater 1 and using the thermal circuit. Hereinafter, as a modification example of each of the above-described embodiments, a method for calculating the end time t0 using a thermal circuit will be described.

[0118] Figure 14 is a schematic diagram in which a virtual thermal circuit is applied to the heater shown in Figure 1. Further, Figure 15 is an enlarged view of part E of Figure 14. As shown in Figures 14 and 15, the above-described heater 1 can be represented by a virtual thermal circuit. Here, i0 is the output of the heater (i.e., the heat flux) (W), C1 is the heat capacity (J / K) of the portion outside the first heating element 14 in the first heating section 12, C2 is the heat capacity (J / K) of the portion inside the first heating element 14 (i.e., on the retort food PF side) in the first heating section 12, C3 is the heat capacity (J / K) of the retort food PF, R1 is the thermal resistance (K / W) from the first heating element 14 to the first cover member 15 side, R2 is the thermal resistance (K / W) from the first heating element 14 to the first structure 13, R3 is the thermal resistance (K / W) of the retort food PF, V1 is the average temperature (°C) outside the first structure 13 (i.e., on the side opposite to the retort food PF side), V2 is the average temperature (°C) inside the first structure 13, V3 is the average temperature (°C) of the retort food PF, i1 is the heat flux (W) flowing into the outside of the first structure 13, i2 is the heat flux (W) flowing into the inside of the first structure 13, i3 is the heat flux (W) flowing into the retort food PF, q1 is the amount of heat (J) accumulated outside the first structure 13, q2 is the amount of heat (J) accumulated inside the first structure, and q3 is the amount of heat (J) accumulated in the retort food PF, respectively.

[0119] Since the thermal circuit shown in Figure 14 has a circuit structure symmetric about the retort food PF, hereinafter, attention is paid to the thermal circuit of the left half of the entire thermal circuit (part E of Figure 14) shown in Figure 15 to detect the temperature of each part. In this case, the heat capacity (J / K) of the retort food PF indicated by C3 is taken as half the value.

[0120] From the thermal circuit shown in Figure 14, the following equation (3) is obtained using Kirchhoff's law.

Equation

[0121] From the above formula (3), the temperatures V2(t) and V3(t) of the first structure 13 and the retort food PF at a certain time t can be expressed by the following formula (4).

Number

[0122] Here, the coefficients a, b, c, λ1, λ2, A, and B can be expressed by the following formula (5) respectively.

Number

[0123] The device constants can be specified as follows. Specifically, first, measure V2 by changing the conditions, and at this time, obtain the device constants that well match the following formula (6). Here, the constants c3 and R3 of the retort food PF are unknown constants at present. On the other hand, when the retort food PF is not set in the installation part 30, it can be considered that c3 is sufficiently small and R3 is sufficiently large. Therefore, for example, set c3 = 1 and R3 = 1000. Since the unknowns are the four device constants c1, c2, R1, and R2, measure four conditions and solve them simultaneously to obtain the device constants.

Number

[0124] Then, measure the temperature V2 of the first structure 13. Specifically, for example, measure the time at four or more points. And identify by fitting. Thus, the device constants can be specified. Note that the least squares method can also be used for fitting. Also, the initial temperatures V1(0) and V2(0) can be changed and measured.

[0125] On the other hand, when heating the object to be heated, calculate the constants c3 and R3 of the unknown object to be heated (for example, the retort food PF) when the structures 13 and 14 are heated. Specifically, the calculation is performed using the above formula (6).

[0126] For example, the case of executing control as shown in FIG. 11 will be described. First, when the heating elements 14 and 24 are operated, the temperatures V2 of the structures 13 and 23 rise. At this time, since there are two unknowns, identification is performed by fitting using the least squares method or the like from any two or more points. For example, by obtaining the temperatures V2(t1) and V2(t2) at two different times at a preset detection time, the constants c3 and R3 are calculated. Next, using the obtained c3 and R3, the end time t0 at which the temperature V3 of the object to be heated reaches the desired temperature is obtained by the following formula (7). Here, for the calculation of the end time t0, an approximate solution can also be obtained using, for example, the Newton-Raphson method.

Number

[0127] In the above-described one modification example, the method of identifying c3 and R3 during the heating of the object to be heated (for example, the retort food PF) and obtaining the heating time (specifically, the end time t0) was exemplified. However, when c3 and R3 can be estimated, for example, when the capacity and type of the object to be heated can be specified, the end time t0 can also be specified by programming a simple relational expression from the above-described formulas (6) and (7).

[0128] When the heat capacity and thermal resistance of the object to be heated are clear, c3 and R3 can also be calculated theoretically. The heat capacity C and the thermal resistance Rth can be specified by the following formula (8).

Number

[0129] In addition, a data sheet such as the one shown in FIG. 6 can be created in advance through experiments or the like, and the end time t0 can also be estimated by comparing the calculated heating rate or temperature change with the data sheet. Also, the data shown in FIG. 6 can be stored in the form of a calculation formula (for example, similar to the above-described formula (2)), and the end time can be calculated from the heating rate or temperature change using the calculation formula.

[0130] The present disclosure is not limited to the above-described embodiments, and various modifications can be made and implemented without departing from the gist of the present disclosure. And all of them are included in the technical idea of the present disclosure.

Explanation of Reference Numerals

[0131] 1 Heater 13 First structure (an example of a structure) 14 First heating element (an example of a heating element) 17 First temperature detection unit (an example of a temperature detection unit) 23 Second structure (an example of a structure) 24 Second heating element (an example of a heating element) 27 Second temperature detection unit (an example of a temperature detection unit) 30 Installation part 40 Control unit PF Retort food (an example of an object to be heated) P Pouch

Claims

1. A step of setting a target temperature of an object to be heated; A step of heating a structure in contact with the object to be heated by operating a heating element; A step of detecting a temperature increase rate of the structure at a predetermined timing after starting the heating; A step of calculating a time for the object to be heated to reach the target temperature from the temperature increase rate; A step of notifying that the time for reaching the target temperature has elapsed, comprising: A method for controlling a heating element.

2. The step of calculating a time for the object to be heated to reach the target temperature from the temperature increase rate applies a virtual thermal circuit to a heater including the heating element, and calculates, from the detected temperature increase rate, a time for the object to be heated to reach the target temperature using the thermal circuit. The method for controlling a heating element according to Claim 1.

3. A step of setting a target temperature of an object to be heated; A step of heating a structure in contact with the object to be heated by operating a heating element; A step of detecting a temperature increase rate of the structure at a predetermined timing after starting the heating; A step of calculating a temperature reached by the structure higher than the target temperature and a time for the object to be heated to reach the target temperature from the temperature increase rate; A step of detecting whether the temperature of the structure has reached the reached temperature; A step of stopping heating of the heating element when it is detected that the temperature of the structure has reached the reached temperature; A step of notifying that the time for reaching the target temperature has elapsed, comprising: A method for controlling a heating element.

4. The predetermined timing is a timing at which a change rate of the temperature increase rate per unit time is within 3%, a timing at which an elapsed time from a preset heating start has elapsed, or a timing at which the structure has reached a preset temperature. The method for controlling a heating element according to Claim 3.

5. The object to be heated contains a liquid, and the heating element is controlled to set the temperature of the liquid to the target temperature. The method for controlling a heating element according to Claim 3.

6. The step of calculating a time for the object to be heated to reach the target temperature from the temperature increase rate applies a virtual thermal circuit to a heater including the heating element, and calculates, from the detected temperature increase rate, a time for the object to be heated to reach the target temperature using the thermal circuit. The method for controlling a heating element according to Claim 3.

7. A step of setting a target temperature of an object to be heated; a step of heating a structure in contact with the object to be heated by operating a heating element; a step of detecting a temperature rising rate of the structure at a predetermined timing after starting the heating; a step of calculating a time for the object to be heated to reach the target temperature from the temperature rising rate; a step of calculating a heating time for performing the heating from the temperature rising rate; a step of detecting whether or not the heating time has elapsed; a step of stopping the heating of the heating element when it is detected that the heating time has elapsed; a step of notifying that the time for reaching the target temperature has elapsed; and a method for controlling a heating element.

8. In the step of calculating the time for the object to be heated to reach the target temperature from the temperature rising rate, a virtual thermal circuit is applied to a heater including the heating element, and the time for the object to be heated to reach the target temperature is calculated using the thermal circuit from the detected temperature rising rate. The method for controlling a heating element according to claim 7.

9. a step of setting a target temperature of an object to be heated; a step of heating a structure in contact with the object to be heated by operating a heating element; a step of detecting a temperature rising rate of the structure at a predetermined timing after starting the heating; a step of calculating a time for the object to be heated to reach the target temperature from the temperature rising rate, and a step of detecting whether or not the temperature of the structure has reached a predetermined upper limit temperature higher than the target temperature; a step of controlling the heating element so as to maintain the upper limit temperature when it is detected that the temperature of the structure has reached the upper limit temperature; a step of notifying that the time for reaching the target temperature has elapsed; and a method for controlling a heating element.

10. In the step of calculating the time for the object to be heated to reach the target temperature from the temperature rising rate, a virtual thermal circuit is applied to a heater including the heating element, and the time for the object to be heated to reach the target temperature is calculated using the thermal circuit from the detected temperature rising rate. The method for controlling a heating element according to claim 9.

11. a step of setting a target temperature of an object to be heated; a step of heating a structure in contact with the object to be heated by operating a heating element; a step of stopping the heating at a predetermined timing after starting the heating; a step of detecting a temperature change of the structure after stopping the heating; a step of calculating a time for the object to be heated to reach the target temperature from the temperature change; A step of operating the heating element to resume heating of the structure; A step of detecting whether the temperature of the structure has reached a predetermined upper limit temperature higher than the target temperature; A step of controlling the heating element to maintain the upper limit temperature when it is detected that the temperature of the structure has reached the upper limit temperature; A step of notifying that the time for reaching the target temperature has elapsed; and A method for controlling a heating element.

12. In the step of calculating the time for the object to be heated to reach the target temperature from the temperature change, a virtual thermal circuit is applied to a heater including the heating element, and from the detected temperature change, the time for the object to be heated to reach the target temperature is calculated using the thermal circuit. The method for controlling a heating element according to claim 11.

13. An installation part where the object to be heated is disposed; A structure that contacts the object to be heated disposed in the installation part; A heating element that heats the structure; A temperature detection part that detects the temperature of the structure; A control part that performs each step of the method for controlling a heating element according to any one of claims 1 to 12 based on the detection result of the temperature detection part; and A heater.

14. The installation part is provided between a pair of the structures facing each other with a predetermined interval therebetween, and the heating element is provided on at least one of the pair of structures. The heater according to claim 13.

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