JP2006318660A - Heating cooking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate false judgment with a temperature detecting means at high temperature in warping judgment of a heated object at its detection temperature rising gradient. <P>SOLUTION: A threshold value used for a first warping detecting operation 8 judging warping of the heated objects 3 by a temperature difference between a first temperature detecting means 5 affected by warping of a bottom of a heated object 3 (a pan), and a second temperature detecting means 6 not affected is determined by a minimum value of the difference from start of heating, so that warping judgment at start of heating in accordance with temperature of a top plate 4 can be made, enabling warping judgment not affected by a previous heating state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heating cooker that performs a warpage determination even when the temperature detected by a temperature detection means for starting heating is high in the warpage determination of the bottom of an object to be heated performed at the start of heating.

  Conventionally, there exists a thing shown in FIG. 5 as this kind of a heating cooker (for example, refer patent document 1).

  In FIG. 5, the heated object 25 is a cooking utensil such as a pan or a frying pan. Ingredients and the like are put in the object to be heated 25 and heated directly or indirectly from the cooking heater 26, and the ingredients in the object to be heated 25 are heated. The cooking heater 26 includes a top plate 27, a temperature sensor 28, a heating source 29, and the like. The cooking heater 26 directly or indirectly heats the heated object 25 placed on the top plate 3, measures the temperature of the heated object 25 from the temperature detected by the temperature sensor 28, and controls the heating. By doing this, the ingredients in the object to be heated 25 are cooked. The top plate 27 is made of glass or the like, and is used for placing the object to be heated 25. The temperature sensor 28 measures the temperature of the object to be heated 25. The heating source 29 is for heating the article to be heated 25.

As shown in FIG. 6, when the difference between the measured value of the temperature sensor 28a arranged in the vicinity of the center and the measured value of the other temperature sensors 28b, 28c, 28d arranged on the outer side is equal to or larger than the reference value, it is heated. It can be determined that the bottom of the pan, which is the object 25, is warped. Here, the center part of the pan may be convex downward in the warp, but the center part becomes concave and the top plate 27 becomes concave except that the placement becomes unstable like a round pan like a Chinese wok. It is assumed that it is a concave warp that floats and the outside is in contact with the top plate 27 and the placement is stable. In the case of a pan with a warp, many errors occur in the measured temperature of the object to be heated 25, so that it can be reflected in the control of cooking such as correction.
JP 2004-164882 A

  However, in the conventional configuration, when heating is started while the measured value of the temperature sensor 28 remains high due to the previous heating, the measured value of the temperature sensor 28a arranged near the center and the other temperature sensors 28b, 28c, 28d. Since the difference from the measured value is different from the case where the temperature sensor 28 starts heating at room temperature, the warpage is misjudged. When the threshold value is switched, if the warpage is erroneously determined, there is a problem that safety such as a decrease in cooking performance or oil ignition may not be ensured.

  The present invention solves the above-mentioned conventional problem, and the detected temperature of the temperature sensor arranged near the center by the previous heating and the detected temperature of other temperature sensors may be high during the bottom surface warpage determination of the object to be heated. The purpose is to realize cooking performance and safety by accurately detecting warpage and switching the threshold value of the temperature rise prevention means according to the detection result.

  In order to solve the above-mentioned conventional problems, the cooking device of the present invention affects the change in heat transfer due to the top plate on which the object to be heated is disposed, the heating coil for heating the object to be heated, and the warp of the object to be heated. The first temperature detecting means for detecting the temperature of the lower surface of the top plate while receiving the heat and the distance from the center of the heating coil that is not affected by the change in heat transfer due to the warpage of the heated object is farther than the first temperature detecting means. The level at which the amount of warpage of the warpage detection means for detecting the amount of warpage of the bottom surface of the object to be heated is determined based on the difference of the second temperature detection means disposed on the second temperature detection means when the heating means starts heating. If the detected temperature of the temperature detecting means is higher than the detected temperature of the first temperature detecting means, the first warp detection is not performed until the first temperature difference is minimized, and the first temperature is not detected. When the difference starts to increase, the first warp detection While start and is obtained by the determining the level for detecting the amount of warp at this time based on the minimum value from the start of heating of the first temperature difference.

  Thus, even when the detected temperature of the first temperature detecting means and the detected temperature of the second temperature detecting means are high due to the previous heating, it is possible to determine the amount of warp without erroneous determination.

  The cooking device of the present invention determines the level of warpage determination by the minimum value from the heating start of the temperature difference of the first temperature detection means and the temperature difference of the second temperature detection means at the start of heating, Even when the detection temperature of the first temperature detection means and the detection temperature of the second temperature detection means are high due to the previous heating, it is possible to determine the amount of warp without erroneous determination.

  In addition, because the control temperature of the means for preventing overheating is changed based on the detected amount of warpage, in a pan with a large amount of warpage, the control temperature is lowered to ensure safety, and in a pan with a small amount of warp, the control temperature is set. Can be increased to maintain high thermal power.

  The first invention relates to a change in heat transfer due to warping of the heated object, a top plate for arranging the heated object, a heating means for heating the heated object, a heating coil disposed below the top plate, and the heated object. The first temperature detection means for detecting the temperature of the lower surface of the top plate while being affected, and the distance from the center of the heating means not affected by the change in heat transfer due to the warp of the object to be heated is the first temperature detection. Second temperature detecting means disposed farther than the means, and a temperature difference detecting operation for obtaining a first temperature difference between the detected temperature of the first temperature detecting means and the detected temperature of the second temperature detecting means, The first warp detecting operation for performing the warp detecting operation for detecting the warp amount of the bottom surface of the object to be heated based on the detected temperature of the temperature difference detecting operation, and the temperature detected by the first temperature detecting means are the first temperature. If it is above, heat the object to be heated. And a first temperature switching means for switching the first temperature based on the amount of warpage detected by the first warpage detecting means, and heating the heating means. When the detection temperature of the second temperature detection means at the start is higher than the detection temperature of the first temperature detection means, the first warp detection is not performed until the first temperature difference is minimized, When the first temperature difference starts to increase, the first warp detection is started. When the level for detecting the warp amount at this time is determined based on the minimum value from the heating start of the first temperature difference. Thus, even when the detected temperature of the first temperature detecting means and the detected temperature of the second temperature detecting means are high due to the previous heating, it is possible to determine the amount of warp without erroneous determination, and the first temperature. Cooking by switching correctly To ensure both the ability and safety.

  In the second invention, in particular, in the first invention, the level at which the amount of warpage is detected is determined on the basis of the time from when the heating means starts heating until the first temperature difference is minimized, Even when the detection temperature of the first temperature detection means and the detection temperature of the second temperature detection means are high due to the previous heating, it is possible to determine the amount of warp without erroneous determination, and to correctly switch the first temperature. This ensures both cooking performance and safety.

  In the third invention, in particular, in the first invention, a difference between the first temperature difference when the heating means starts heating at a level at which the amount of warpage is detected and the minimum value of the first temperature difference is calculated. By determining on the basis, even when the detection temperature of the first temperature detection means and the detection temperature of the second temperature detection means are high due to the previous heating, it is possible to determine the amount of warp without erroneous determination, By correctly switching the first temperature, both cooking performance and safety are ensured.

  According to a fourth aspect of the present invention, in particular, in the first aspect of the invention, the level at which the amount of warpage is detected is determined based on the amount of time change of the first temperature difference. Even when the detected temperature and the detected temperature of the second temperature detecting means are high, it is possible to determine the amount of warp without erroneous determination, and by correctly switching the first temperature, both cooking performance and safety can be achieved. Secure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
FIG. 1 is a block diagram showing a first embodiment of an induction heating cooker according to the present invention. In FIG. 1, an induction heating device 2 includes a heating power control means 2a that converts and supplies a commercial AC power source 1 into a high-frequency current, a high-frequency current source 2b, and a heating coil 2c. It is placed on the top plate 4 installed on the upper surface of.

  The first temperature detecting means 5 measures the temperature by changing the resistance value of the first thermistor 5 a of the temperature detecting element provided so as to be in contact with the lower surface of the top plate 4. The first temperature detection means 5 is affected by a change in heat transfer due to warping of the article 3 to be heated. The second temperature detection means 6 is provided so as to be in contact with the lower surface of the top plate 4 and is provided with a second thermistor 6a of the temperature detection element provided on the outer peripheral side of the heating coil 2c as compared with the first thermistor 5a. The temperature is measured by changing the resistance value. The second temperature detection means 6 is not affected by a change in heat transfer due to warpage of the article 3 to be heated.

  The temperature difference detection means 7 detects the temperature difference between the temperature detected by the first temperature detection means 5 and the temperature detected by the second temperature detection means 6, and the first warpage detection means 8 is the temperature difference detection means 7. The amount of warpage of the bottom surface of the object to be heated 3 is detected from the detected temperature difference.

  The change amount detection means 9 detects the change amount in the Δt time of the temperature difference detected by the temperature difference detection means 7.

  The over-temperature prevention means 10 stops heating the object to be heated 3 based on the first detected temperature 15 detected by the first temperature detecting means 5 or reduces the output of the heating, thereby detecting the first detected temperature 15. When the temperature exceeds a predetermined first temperature, a signal for reducing the heating output is transmitted to the heating power control means 2a.

  The first temperature switching means 11 switches the first temperature based on the detection result of the first warp detection operation 8.

  FIG. 2 shows the transition of the temperature detected by the temperature detecting means of the cooking device according to the present invention.

  In FIG. 2, the first detected temperature 12 is the time transition of the temperature detected by the first temperature detecting means 5 and the second detected temperature 13 is the second temperature when the pan bottom warpage amount of the object to be heated is small. The first temperature difference 14 represents the time transition of the temperature difference detected by the temperature difference detecting means 7.

  In FIG. 3, the first detected temperature 15 is the temperature detected by the first temperature detecting means 5 when the amount of warping of the bottom of the object 3 to be heated is small when the top plate 4 is not cooled after the previous heating. The second detected temperature 16 represents the time transition of the temperature detected by the second temperature detecting means 6, and the first temperature difference 17 represents the time transition of the temperature difference detected by the temperature difference detecting means 7. Yes.

  Tmin 118 indicates the time when the first temperature difference 17 is minimized, and tem 119 indicates the value of the first temperature difference 17 at Tmin 118.

  In FIG. 4, the first detected temperature 20 is the time of the temperature detected by the first temperature detecting means 5 when the pan bottom warping amount of the object to be heated is large in the state where the top plate 4 is not cooled after the previous heating. The second detection temperature 21 represents the time transition of the temperature detected by the second temperature detection means 6, and the first temperature difference 22 represents the time transition of the temperature difference detected by the temperature difference detection means 7. .

  Tmin 223 indicates the time when the first temperature difference 22 is minimized, and tem 224 indicates the value of the first temperature difference 22 when Tmin 223 is reached.

  The operation of the induction heating cooker shown in FIGS. 1 and 2 will be described below.

  The thermal power control means 2a controls the output of the high frequency current source 2b so as to heat the article 3 to be heated with the thermal power corresponding to the set thermal power, and supplies the high frequency current to the heating coil 2c.

  The first temperature detection means 5 detects the bottom surface temperature of the article to be heated 3 propagated through the top plate 4 as the first detection temperature 12. The second temperature detection means 6 detects the bottom temperature of the heated object 3 on the outer peripheral side of the heating coil 2 c from the first temperature detection means 5 as the first detection temperature 13, and the first detection temperature 12. Compared with, temperature followability is poor.

  In FIG. 2, when the object to be heated 3 having no concave warp on the bottom due to the warp of the pan is heated, the second detection temperature 13 starts to rise immediately after the heating, and then the first detection temperature 12 starts to rise. At this time, the first temperature difference 14 becomes minimum at the temperature difference lowest point tb and then increases.

  In the first warpage determination operation 8, the warpage determination operation is started from the heating start time t0, and the time ts when the first temperature difference 14 exceeds the predetermined temperature difference threshold Te1 may be within the predetermined time threshold tsh1. Therefore, it is determined that there is no warping. Therefore, it is determined that there is no warpage in FIG.

  As shown in FIG. 3, after heating, for example, when heating is started in a nonmagnetic pan and then heating is started in a magnetic pan, the first detection temperature 15, the heating coil 2 c and the top plate 4 are not heated when the nonmagnetic pan is heated. When a partition plate (not shown) for reducing buoyancy that is placed between them and acts on the pan by a magnetic field becomes high temperature and heating is started while the second detection temperature 16 in the vicinity remains high, the first detection temperature 15 and the second detection temperature 16 both decrease and increase again. Since the temperature at the start of heating is higher at the second detected temperature 16, the second detected temperature 16 is steeper when the temperature is lowered. For this reason, the first temperature difference 17 once increases again through the lowest point. At this time, if the determination is made using the temperature difference threshold Te1 used in the first warpage determination operation 8 of FIG. 2, the time when the predetermined temperature difference threshold Te1 is exceeded exceeds the predetermined time threshold tsh1, and there is no warpage. If the first temperature difference 17 <0 at the start of heating is erroneously determined that the pan is warped, the threshold Te1 is set by the time Tmin118 from the start of heating to the lowest point, and the first warp The determination operation 8 is performed. Therefore, in FIG. 3, since the time from the start of heating to the lowest point does not exceed Tmin 118, it is determined that there is no warp.

  As shown in FIG. 4, when the object to be heated 3 has a concave warp, the temperature followability of the first temperature detecting means 20 is deteriorated, so the time Tmin223 from the start of heating to the lowest point becomes Tmin118 <Tmin223, It is judged that there is a warp.

  Therefore, when the top plate 4 starts to be heated at a high temperature, it is determined by the first temperature difference at the start of heating (if <0), and the threshold value of the first warp detection means is set to the value at the start of heating. By determining the threshold value of the first warp detection means based on the time Tmin at the lowest point of the first temperature difference regardless of the detected temperature difference between the first temperature detection means 5 and the second temperature detection means 6. In addition, it is possible to determine the pan bottom warpage of the article 3 to be heated.

(Embodiment 2)
The configuration of the induction heating cooker of the second embodiment is the same as that of the first embodiment.

  As shown in FIG. 3, based on the temperature difference tem1 at the lowest point of the first temperature difference 17 when the amount of warping of the pan bottom of the article 3 to be heated is small when the top plate 4 is not cooled after the previous heating. After the threshold value of the first warp detection operation 8 is determined and the first detection temperature 12 and the second detection temperature 13 return to normal behavior (not high temperature at the start of heating) as shown in FIG. Then, the detection operation is performed again to determine the warpage. As shown in FIG. 4, when the object 3 to be heated has a concave warp, the absolute value tem119 <tem224 of the temperature difference at the lowest point is determined, and it is determined that there is a warp.

  Alternatively, the threshold value of the first warp detection operation 8 is determined based on the difference between the first temperature difference 17 at the start of heating and the temperature difference tem1 at the lowest point, as shown in FIG. After the detection temperature 12 and the second detection temperature 13 return to normal behavior (not high temperature at the start of heating), the detection operation is performed again to determine warpage. As shown in FIG. 4, when the object to be heated 3 is warped, (the difference between the first temperature difference 17 at the start of heating and the temperature tem 119 at the lowest point) <(the first temperature at the start of heating). Temperature difference 22 and tem 119), and it is determined that there is a warp.

  Further, the threshold value of the first warp detection operation 8 is determined based on the temporal change amount of the first temperature difference 17 from the start of heating to the lowest point, and the first detected temperature 12 and the first detected temperature 12 as shown in FIG. After the second detection temperature 13 returns to normal behavior (not high temperature at the start of heating), the detection operation is performed again to determine warpage. As shown in FIG. 4, when the object 3 to be heated has a concave warp, the temperature followability of the first temperature detecting means 20 is deteriorated, so that the first temperature difference 17 from the start of heating to the lowest point is reduced. The amount of time change is smaller than the threshold value, and it is determined that there is a warp. Regardless of the temperature detected by the first temperature detection means 5 and the second temperature detection means 6 at the start of heating, it is possible to determine the pan bottom warpage of the article 3 to be heated.

  In the above embodiment, the case where the plate-like partition plate is provided has been described. However, when the rod-like plate crosses over the center of the coil, or there is no partition plate, the second temperature sensor is provided outside the first temperature detecting means. Even when the temperature detection means is provided, the same effect can be obtained when the detection temperature of the second detection means becomes high at the start of heating.

  Moreover, although the induction heating cooker has been described, other heating means such as a radial heating means and a halogen heating means may be used. The temperature detecting means is not limited to the thermistor. In addition, the threshold used for determination and the sampling interval for obtaining the temperature difference increase are not unique and must be designed for each device.

  As described above, the heating cooker according to the present invention determines the warping of the bottom surface of the object to be heated regardless of the previous heating state or the temperature state of the top plate, so that the heating device is affected by the warping of the object to be heated. It can also be applied to other uses.

The block diagram which shows the induction heating cooking appliance in Embodiment 1, 2 of this invention The figure which shows the behavior of the temperature detection means in case the curvature of the pan in Embodiment 1, 2 of this invention is small. The figure which shows the behavior of the temperature detection means when the curvature of the pan at the high temperature start in Embodiment 1, 2 of this invention is small The figure which shows the behavior of the temperature detection means when the curvature of the pan at the high temperature start in Embodiment 1, 2 of this invention is large. Cross-sectional view of a conventional cooking device Temperature sensor layout diagram of a conventional cooking device

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 To-be-heated object 5 1st temperature detection means 6 2nd temperature detection means 7 Temperature difference detection means 8 1st curvature detection operation 10 Overtemperature rise prevention means

Claims (4)

A top plate on which an object to be heated is disposed, a heating means for heating the object to be heated, a heating coil disposed below the top plate, and the top while being affected by a change in heat transfer due to warpage of the object to be heated. A first temperature detecting means for detecting the temperature of the lower surface of the plate, and a distance from the center of the heating means that is not affected by a change in heat transfer due to warping of the object to be heated is disposed farther than the first temperature detecting means. Second temperature detection means, a temperature difference detection operation for obtaining a first temperature difference between the detection temperature of the first temperature detection means and the detection temperature of the second temperature detection means, and the temperature difference detection operation A first warp detecting operation for performing a warp detecting operation for detecting the amount of warping of the bottom surface of the object to be heated based on the detected temperature, and when the temperature detected by the first temperature detecting means is equal to or higher than the first temperature. Stop or increase the heating of the object And a first temperature switching means for switching the first temperature based on the amount of warpage detected by the first warpage detection means, when the heating means starts heating. If the detected temperature of the second temperature detecting means is higher than the detected temperature of the first temperature detecting means, the first warp detection is not performed until the first temperature difference is minimized, and the first temperature detecting means is not used. When the temperature difference of 1 starts to increase, the first warpage detection is started, and the level for detecting the warpage amount at this time is determined based on the minimum value from the start of heating of the first temperature difference. vessel. The cooking device according to claim 1, wherein the level at which the amount of warpage is detected is determined based on the time from when the heating means starts heating until the first temperature difference is minimized. The cooking device according to claim 1, wherein a level at which a warpage amount is detected is determined based on a difference between a first temperature difference when the heating means starts heating and a minimum value of the first temperature difference. The cooking device according to claim 1, wherein a level at which the amount of warpage is detected is determined based on a temporal change amount of the first temperature difference.