JP4258417B2 - Electric jar rice cooker - Google Patents

Description

  The present invention relates to an electric jar rice cooker that keeps a cooked food in a pan detachably stored in a rice cooker body.

  Conventionally, an electric jar rice cooker has been proposed in which the heat retention program is variable depending on the heat retention amount. Hereinafter, the configuration will be described.

  As shown in FIG. 3, the rice cooker body 1 has an upper surface opened, and a protective frame 3 made of a highly heat-resistant resin material that is a storage part of the pan 2 is disposed inside the rice cooker body 1. The upper end portion of the protective frame 3 is engaged with the upper frame 4 constituting the upper surface opening of the rice cooker body 1. A heating coil 5 that is a pan heating means for induction heating the pan 2 is provided outside the protective frame 3, and a bottom sensor 6 that is a pan temperature detecting means is provided at the bottom center of the protective frame 3.

  The top opening of the rice cooker body 1 is covered with a lid 7 so as to be opened and closed, and the lid 7 is supported by a hinge shaft 8 so as to be opened and closed. The steam port 9 is for discharging steam during cooking. The lid heater 10 constitutes a lid heating means and heats the lower surface of the lid 7. The control board 11 controls the power supply to the heating coil 5 and the lid heater, reads the signal of the bottom sensor 6, and has a time measuring means.

  In the above configuration, after starting the heat insulation, the time required for the temperature change between the first pan temperature and the second pan temperature is calculated to estimate the heat insulation amount, and the heat insulation performance is improved with the corresponding heat insulation program. (For example, refer to Patent Document 1).

In addition, there has been proposed an electric jar rice cooker that includes a room temperature sensor and a weight sensor and detects the ambient temperature and the amount of heat retention and improves the heat retaining performance with a corresponding heat retaining program (see, for example, Patent Document 2).
JP 2002-010910 A Japanese Examined Patent Publication No. 1-2724

  However, in the former electric jar rice cooker, the determination result is greatly influenced by the ambient temperature and the user's loosening work, and the bottom sensor 6 is affected by the ambient temperature, and the actual maintenance temperature in the heat insulation temperature maintenance process is actually There was a difference in the maintenance temperature, and it was not always possible to maintain the optimum temperature.

Moreover, in the latter electric jar rice cooker, for example, the temperature retention due to fluctuations in the detection temperature of the room temperature sensor due to self-heating during rice cooking, voltage fluctuations in the power supply, and variations in the output of the heating coil and heater in each rice cooker Due to the difference between the assumed input power in the program and the input power of the actual heating coil and lid heater, the optimum heat insulation has not necessarily been achieved.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and has an object to automatically detect an ambient temperature and realize optimum heat retention.

In order to achieve the above-mentioned object, the present invention detachably stores a pan for putting food into the rice cooker body, controls the energization of the pan heating means for heating the pan by the control means, and controls the temperature of the food to the pot temperature. The detection means is configured to detect the weight of the food by the weight detection means, and the control means is calculated by the output change of the pan temperature detection means, the output of the weight detection means, and the output of the timing means , Insulation weight of the cooked food is Wr, specific heat is R, the heat capacity of the whole rice cooker is Wb, the heat dissipation coefficient of the whole rice cooker is α, the elapsed time of the measurement point is t1, the detection temperature of the bottom sensor at the start of measurement is Ta, When the detection temperature of the bottom sensor at the end is Tb and the ambient temperature is Tr
Tr = (Ta + Tb) / 2−t1 × α / (Ta−Tb) / (Wr × R + Wb)
The ambient temperature is estimated by the following formula , and the heat retention process is corrected.

  As a result, the ambient temperature is automatically detected, and the optimum heat retention can be realized regardless of the ambient temperature.

  The electric jar rice cooker of this invention can implement | achieve optimal heat retention irrespective of the dispersion | variation in ambient temperature, supply power supply voltage, and the output of the heating means of each rice cooker.

1st invention is a rice cooker main body, the pan which puts the food detachably accommodated in the said rice cooker main body, the pan heating means which heats the said pan, and the control means which controls electricity supply of the said pan heating means And a pan temperature detecting means for detecting the temperature of the cooked food, a weight detecting means for detecting the weight of the cooked food, and a time measuring means for clocking, wherein the control means includes an output change of the pan temperature detecting means, Calculated based on the output of the weight detection means and the output of the timing means, the heat retention weight of the cooked food is Wr, the specific heat is R, the heat capacity of the whole rice cooker is Wb, the heat dissipation coefficient of the whole rice cooker is α, and the measurement point When the elapsed time is t1, the detection temperature of the bottom sensor at the start of measurement is Ta, the detection temperature of the bottom sensor at the end of measurement is Tb, and the ambient temperature is Tr
Tr = (Ta + Tb) / 2−t1 × α / (Ta−Tb) / (Wr × R + Wb)
Ambient temperature is estimated by the equation (1) , and the heat retention process is corrected. In the heat retention process, the ambient temperature is estimated from the output change of the pan temperature detection means, the output of the weight detection means, and the output of the timing means. Thus, the ambient temperature is automatically detected. When the ambient temperature is low, the lid heating means is relatively energized. Conversely, when the ambient temperature is high, the lid heating means is relatively energized. Thus, it is possible to correct the heat retention process as described above, and to realize the optimum heat retention regardless of the ambient temperature.

In a second aspect based on the first aspect, the control means is configured such that the energizing power to the pan heating means is Pr, t2 when energizing a predetermined amount, Tb the bottom sensor detection temperature before energization, and the bottom sensor detection after energization. When the temperature is Tc
The input power of the pan heating means is estimated by the equation Pr = α ((Tb + Tc) / 2−Tr) − (Tc−Tb) × (Wr × R + Wb) / t2, and the heat retention process is corrected. By comparing the output change data of the pot temperature detection means at multiple levels, such as when a predetermined amount of electricity is applied to the pot heating means, or when no energization is applied to the pot heating means, The input power of the means can be estimated and the heat retention process can be corrected to achieve optimum heat retention.

3rd invention is the lid heating means which heats the said heating plate in the said 1st invention, the cover provided so that the upper surface opening part of the rice cooker main body might be covered, the lower surface of the said cover, and the said heating plate When the energizing power to the lid heating means is Qr, t3 is energized for a predetermined amount, Tc is the bottom sensor detection temperature before energization, and Td is the bottom sensor detection temperature after energization.
Qr = (Tc−Td) × (Wr × R + Wb) / t3-α ((Tc + Td) / 2−Tr) is used to estimate the input power of the lid heating means and correct the heat retention process. After heating starts, the lid heating is performed by comparing the output change data of the pan temperature detection means at multiple levels, such as when a predetermined amount of electricity is applied to the lid heating means, or when no electricity is supplied. It is possible to estimate the input power of the means, and to realize an optimum heat retention.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the control means corrects the heat retention maintenance temperature based on the estimated ambient temperature, and the pan is calculated from the estimated ambient temperature. Judging the influence of the ambient temperature on the temperature detection means, for example, increasing the input value slightly because the rice temperature tends to be kept lower at 35 ° C than the target heat retention temperature set at 20 ° C. By correcting the input value of the heat retention maintenance temperature, the optimum heat retention can be realized.

  A fifth invention is the process according to any one of the first to fourth inventions, wherein the control means detects the operation of the user by the change in the output of the weight detection means, and determines the ambient temperature and the input power of the pot heating means. Detects operations such as opening / closing the lid of the user and unwinding rice, which affect the estimation of the ambient temperature and the input power of the pan heating means from the output change of the weight detection means. Thus, by correcting the determination process of the ambient temperature and the input power of the pan heating means, the determination can be prevented in advance, and the optimum heat retention can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
As shown in FIG. 1, the rice cooker body 12 has an open top surface, and a protective frame 14 made of a highly heat-resistant resin material that is a storage part of the pan 13 is disposed inside the rice cooker body 12. The upper end portion of the protective frame 14 is engaged with the upper frame 15 that constitutes the upper surface opening of the rice cooker body 12. A heating coil 16 which is a pan heating means for induction heating the pan 13 is provided outside the protective frame 14, and a bottom sensor 17 which is a pan temperature detecting means is provided at the center of the bottom of the protective frame 14 so as to contact the pan 13. Yes. The weight sensor 18 constitutes weight detection means and detects the weight of the pan 13. The weight sensor 18 is located at the bottom of the bottom sensor 17, and the rice / water serving as the cooked food 19 is displaced by displacement of a load cell (not shown). Measure the weight.

  An opening on the upper surface of the rice cooker body 13 is covered with a lid 20 so as to be opened and closed. The lid 20 is supported by a hinge shaft 21 so as to be opened and closed. A heating plate 25 is disposed on the lower surface of the lid 20. The steam port 22 is for discharging steam during cooking. The lid heater 23 constitutes a lid heating means and heats the heating plate 25 disposed on the lower surface of the lid 20. When the lid 20 is closed, the pot packing 24 comes into contact with the upper side of the pot 13 and seals the pot 13.

  The control board (control means) 26 controls the power supply to the heating coil 16 and the lid heater 23, and also includes a time measuring means (not shown) that reads signals from the bottom sensor 17 and the weight sensor 18 and performs a time measuring operation. Have.

  Here, the control board (control means) 26 estimates the ambient temperature based on the output change of the bottom sensor 17 and the output of the output timing means of the weight sensor 18 and corrects the heat retention process.

  The operation and action of the above configuration will be described with reference to FIG. FIG. 2 is a correlation diagram of the pan temperature, the energization sequence to the heating coil 16 and the lid heater 23, and time in the determination process for heat retention. In FIG. 2, 27 is a pan temperature, 28 is an energization state to the heating coil 16, 29 is an energization state to the lid heater 23, A, B, C and D are measurement points, Ta, Tb, Tc and Td are A, Temperatures at points B, C, and D, t1, t2, and t3 are times between A to B, B to C, and C to D, respectively.

  Rice / water, which is the food 19, is added to the pan 13 to cook rice. The temperature is kept warm and the pan temperature detected by the bottom sensor 17 is lowered to Ta. When time t1 elapses without energization, the pan temperature decreases and becomes Tb. Next, when the heating coil 16 is energized for a time t2, the pan temperature changes and Tc is detected. Further, when the lid heater 23 is energized for a time t3, the pan temperature changes and becomes Td.

  Here, the weight of the heated rice detected by the weight sensor 18 is Wr, the specific heat of the cooked rice is R, the heat capacity of the whole rice cooker is Wb, the heat dissipation coefficient of the whole rice cooker is α, and the actual input power by the heating coil 16 is Pr, the design input power by the heating coil 16 is Pi, the actual input power by the lid heater 23 is Qr, the design input power by the lid heater 23 is Qi, and the ambient temperature is Tr.

  The fact that the temperature of the rice cooker dropped from Ta to Tb during time t1 means that the amount of heat of (Ta-Tb) × (Wr × R + Wb) was lost during t1, but the loss time is Since this is approximately proportional to the difference between the average temperature (Ta + Tb) / 2 and the ambient temperature Tr, the following equation is established.

t1 = (Ta−Tb) × (Wr × R + Wb) / α ((Ta + Tb) / 2−Tr)
From this, the ambient temperature Tr can be estimated by the following equation.

Tr = (Ta + Tb) / 2−t1 × α / (Ta−Tb) / (Wr × R + Wb)
As described above, when the ambient temperature Tr is estimated more accurately than in the past, if the temperature is higher than 30 ° C., the temperature is maintained at 73 ° C. If the temperature is 30 ° C. or lower, the temperature lower than 73 ° C. is selected. The heat retention performance can be improved by correcting the heat retention process.

  As described above, in the present embodiment, the ambient temperature is estimated by the output change of the bottom sensor 17, the output of the weight sensor 18, and the output of the time measuring means, and the warming process is corrected. The temperature can be accurately estimated. When the ambient temperature is low, the lid heater 23 is relatively energized. Conversely, when the ambient temperature is high, the lid heater 23 is relatively energized. In this way, the heat retention process can be corrected, and optimum heat retention can be realized regardless of the ambient temperature.

(Embodiment 2)
The control board (control means) 26 shown in FIG. 1 estimates the input power of the heating coil 16 by comparing the output change data of the bottom sensor 17 when the heating coil 16 is energized by a predetermined amount and when it is not energized. I am trying to correct the process. Other configurations are the same as those of the first embodiment.

  The operation and action of the above configuration will be described with reference to FIG. When energization occurs during time t2 and the temperature rises, the rice cooker has a heat quantity of (Tc−Tb) × (Wr × R + Wb) approximately proportional to the difference between the average temperature (Tb + Tc) / 2 and the ambient temperature Tr. Although it is lost, since the temperature tends to rise due to the amount of heat (Pr × t2) obtained by the actual input power Pr during the time t2, the following equation is established.

t2 = (Pr × t2− (Tc−Tb) × (Wr × R + Wb))
/ Α ((Tb + Tc) / 2−Tr)
From this, the actual input power Pr of the heating coil 16 can be estimated by the following equation.

Pr = α ((Tb + Tc) / 2−Tr)
− (Tc−Tb) × (Wr × R + Wb) / t2
Based on the actual input power Pr of the heating coil 16 obtained in this way, when the energization time to the heating coil 16 on the heat retention program considered to be optimum selected from the heat-insulated rice weight is tn, the actual current energization time is tn. If it correct | amends x (Pi / Pr), the heating as a design aim can be implement | achieved and a good heat retention performance can be implement | achieved.

  As described above, in the present embodiment, the input power of the heating coil 16 is estimated by correcting the output change data of the bottom sensor 17 when the heating coil 16 is energized with a predetermined amount and when it is not energized, and the heat retention process is corrected. As a result, the input power of the heating coil 16 can be accurately estimated, and the heat retention process can be corrected to achieve optimum heat retention.

  In the present embodiment, the input power of the heating coil 16 is estimated by comparing the output change data of the bottom sensor 17 when the heating coil 16 is energized with a predetermined amount and when it is not energized. The input power of the heating coil 16 may be estimated by comparing the output change data of the bottom sensor 17 at the time of energizing the predetermined amount and the amount of energization different from the predetermined amount, and the same operation and effect can be obtained. it can.

(Embodiment 3)
The control board (control means) 26 shown in FIG. 1 estimates the input power of the lid heater 23 by comparing output change data of the bottom sensor 17 when the lid heater 23 is energized by a predetermined amount and when it is not energized. I am trying to correct. Other configurations are the same as those of the first embodiment.

  The operation and action of the above configuration will be described with reference to FIG. When the lid 20 is energized only during the time t3 and the pan temperature falls, the rice cooker is obtaining heat (Qr × t3) from the actual input power Qr from the lid heater 23 during the time t3. Since the amount of heat of (Tc−Td) × (Wr × R + Wb) is lost and the temperature drops almost in proportion to the difference between the average temperature (Tc + Td) / 2 and the ambient temperature Tr, the following equation is established.

t3 = ((Tc−Tb) × (Wr × R + Wb) −Qr × t3)
/ Α ((Tc + Td) / 2−Tr)
From this, the actual input power Qr of the lid heater 23 can be estimated by the following equation.

Qr = (Tc−Td) × (Wr × R + Wb) / t3
−α ((Tc + Td) / 2−Tr)
Based on the actual input power Qr of the lid heater 23 obtained in this way, when the energization time to the lid heater 23 on the warming program selected from the warming rice weight is tf, the actual energization time is tf. If it correct | amends x (Qi / Qr), the heating as a design aim can be implement | achieved and a good heat retention performance will be realizable.

  As described above, in the present embodiment, the input power of the lid heater 23 is estimated by comparing the output change data of the bottom sensor 17 when the lid heater 23 is energized by a predetermined amount and when it is not energized, and the heat retention process is corrected. Since it did in this way, the input electric power of the lid | cover heater 23 can be estimated correctly, and also optimal heat insulation can be implement | achieved.

In the present embodiment, the input power of the lid heater 23 is estimated by comparing the output change data of the bottom sensor 17 when the lid heater 23 is energized with a predetermined amount and when it is not energized.
3 may be estimated by comparing the output change data of the bottom sensor 17 when a predetermined amount of electricity is supplied to 3 and when an amount of electricity different from the predetermined amount is supplied, and the same operation and effect can be obtained. Can do.

(Embodiment 4)
The control board (control means) 26 shown in FIG. 1 corrects the heat retention maintenance temperature based on the estimated ambient temperature. Other configurations are the same as those of the first embodiment.

  The operation and action of the above configuration will be described. When it is known that the actual maintenance temperature is G2 with respect to the design target maintenance temperature G1 at the insulation temperature maintenance temperature input value g1 at the ambient temperature Tr when the insulation temperature maintenance temperature input value is g1, the maintenance temperature input value is If it correct | amends with g1 + (G1-G2), the heating as a design aim can be implement | achieved and good heat retention performance will be realizable.

  As described above, in this embodiment, since the heat retention maintaining temperature is corrected based on the estimated ambient temperature, the influence of the ambient temperature on the bottom sensor 17 from the estimated ambient temperature is determined, for example, 20 ° C. The rice temperature tends to be kept lower during the 35 ° C than the target heat retention temperature set in the middle, so the input value of the heat retention maintenance temperature is corrected, for example, by slightly increasing the input value. Can be realized.

(Embodiment 5)
The control board (control means) 26 shown in FIG. 1 detects the operation of the user based on the output change of the weight sensor 18 and corrects the determination process of the ambient temperature and the input power of the heating coil 16. Other configurations are the same as those of the first embodiment.

  The operation and action of the above configuration will be described. When the lid 20 is opened, the load received by the pan 13 from the pan packing 24 disappears, so that a change appears in the signal from the weight sensor 18 that measures the weight of the pan 13. By detecting changes in the output of the weight sensor 18 that affect the estimation of the ambient temperature and the input power of the heating coil 16, the user opens / closes the lid 20, loosens the rice, or turns the By correcting the determination process of the temperature and the input power of the heating coil 16, erroneous determination can be prevented in advance, and optimal heat retention can be realized.

  During this determination, when the signal from the weight sensor 18 changes, the determination is canceled, and the operation of the user opening / closing the lid 20, loosening rice, or wobbling is finished, and the signal from the weight sensor 18 is changed. After stabilization, by starting the determination again, the influence of the disturbance during the determination is eliminated, and an accurate determination can be made.

  As described above, in the present embodiment, the operation of the user is detected based on the output change of the weight sensor 18 and the determination process of the ambient temperature and the input power of the heating coil 16 is corrected. By detecting operations such as opening / closing of the lid 20 and rice unwinding that affect the estimation of the ambient temperature and the input power of the heating coil 16 from the change, the ambient temperature and the input power of the heating coil 16 are detected. By correcting the determination process, erroneous determination can be prevented in advance, and optimal heat retention can be realized.

  In this embodiment, a method of selecting a heat retention program first from the weight of the heat-retained rice and correcting it is mentioned, but the basic heat retention program is made constant, the ambient temperature and each heating means A method of calculating the correction coefficient from the actual input power and the weight of the heated rice and correcting it with respect to the basic program can also realize a good heat retention performance as designed.

  Further, as the weight detection method, in this embodiment, a method by measuring the displacement of the load cell is adopted, but the weight detection method is not limited.

  Furthermore, although the temperature change data at a certain time is used as the estimation method of the ambient temperature and the output of the heating means, it can be estimated from the time data concerning the change between the certain temperatures.

  In addition, an induction heating method is used as the pan heating means and a heater method is used as the lid heating means, but the heating method is not limited.

  As described above, the electric jar rice cooker according to the present invention can achieve optimum heat retention regardless of variations in ambient temperature, supply power supply voltage, and output of heating means of individual rice cookers. It is useful as an electric jar rice cooker that keeps the food in the pan stored detachably in the main body.

Sectional drawing of the electric jar rice cooker in Embodiment 1 of this invention Time chart showing the heat insulation process of the electric jar rice cooker Cross section of a conventional electric jar rice cooker

Explanation of symbols

12 Rice cooker body 13 Pot 16 Heating coil (pot heating means)
17 Bottom sensor (pan temperature detection means)
18 Weight sensor (weight detection means)
26 Control board (control means)

Claims (5)

A rice cooker body, a pan for putting the food detachably stored in the rice cooker body, a pan heating means for heating the pan, a control means for controlling energization of the pan heating means, and the temperature of the cooked food A pan temperature detecting means for detecting the weight of the cooked food, a weight detecting means for detecting the weight of the food, and a time measuring means for timing, wherein the control means outputs an output change of the pan temperature detecting means and an output of the weight detecting means. And the warming weight of the cooked food is Wr, the specific heat is R, the heat capacity of the whole rice cooker is Wb, the heat dissipation coefficient of the whole rice cooker is α, the elapsed time of the measurement point is t1, When the detection temperature of the bottom sensor at the start is Ta, the detection temperature of the bottom sensor at the end of measurement is Tb, and the ambient temperature is Tr
Tr = (Ta + Tb) / 2−t1 × α / (Ta−Tb) / (Wr × R + Wb)
An electric jar rice cooker that estimates the ambient temperature using the formula and corrects the heat retention process. When the energizing power to the pan heating means is Pr, t2 is when a predetermined amount is energized, Tb is the bottom sensor detection temperature before energization, and Tc is the bottom sensor detection temperature after energization.
Claim that the input power of the pan heating means is estimated by the formula Pr = α ((Tb + Tc) / 2−Tr) − (Tc−Tb) × (Wr × R + Wb) / t2, and the heat retention process is corrected. Item 1. An electric jar rice cooker according to item 1. A lid provided so as to cover the opening of the rice cooker body, a heating plate disposed on the lower surface of the lid, and a lid heating means for heating the heating plate, the control means supplies the energization power to the lid heating means Qr, when t3 is energized for a predetermined amount, Tc is the bottom sensor detection temperature before energization, and Td is the bottom sensor detection temperature after energization.
Claim that the input heat of the lid heat means is estimated by the equation of Qr = (Tc−Td) × (Wr × R + Wb) / t3−α ((Tc + Td) / 2−Tr) to correct the heat retention process. Item 1. An electric jar rice cooker according to item 1. The electric jar rice cooker according to any one of claims 1 to 3, wherein the control means corrects the heat retention maintenance temperature based on the estimated ambient temperature. 5. The control unit according to claim 1, wherein the control unit detects a user operation based on an output change of the weight detection unit, and corrects the determination process of the ambient temperature and the input power of the pan heating unit. Electric jar rice cooker.

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