JP4579187B2 - rice cooker - Google Patents

Description

  The present invention relates to a rice cooker capable of baking cake dough.

  This type of rice cooker includes a rice cooker body that houses a rice cooker and a lid that is attached to the rice cooker body so as to be openable and closable. Inside the rice cooker body, heating means for heating the rice cooker and a temperature sensor for the pan for detecting the temperature of the rice cooker are arranged. Also. A lid temperature sensor for detecting the space temperature of the upper portion of the rice cooker is disposed inside the lid. And based on the detected value of these temperature sensors, the cooked rice set in the rice cooking pan is cooked.

  In recent years, cooking methods at home have diversified, and in rice cookers, the need for cooking other than rice cooking is increasing, and related to rice cookers that can bake cake dough like the present invention Prior art document information to be included includes the following.

JP 2004-65630 A

  In this patent document 1, the rice cooker carrying the cake dough course which consists of a standby process, a heating process, a preheating process, and a baking process is described. Among them, the heating step is to operate the pot bottom heating means disposed at the bottom of the rice cooking pot and the lid heating means disposed on the lid to raise the temperature to a preset first set temperature. In the preheating step, the pan bottom heating means is stopped, and the temperature is raised to a preset second temperature by preheating the pan bottom heating means and heating by the lid heating means. The baking process is to adjust the baking (color) of the surface layer of the dough by controlling the pan bottom heating means and the lid heating means on and off.

  However, in this rice cooker, the pot bottom heating means is a heating plate having a heater inside because it includes a drawing and a preheating process using preheating. And in this heating plate type rice cooker, it is very difficult to adjust the baked color by on / off control in that it has residual heat, and there is a problem that it is highly likely to cause scorching.

  In the present invention, it is an object to provide a rice cooker that can be baked with good baking color at the required location and good baking up to the inside without scorching the surface layer of the cake dough.

In order to solve the above-mentioned problems, the rice cooker of the first invention includes a rice cooker body that houses a rice cooker, a pot bottom heating unit that heats the bottom of the rice cooker, and a lid heating unit that heats the top of the rice cooker. And a temperature detection means for detecting the temperature of the rice cooking pan, and in the rice cooker that controls the heating means based on the detection value of the temperature detection means to execute the rice cooking control, the heating means is operated. After performing the baking process, a cake dough course is provided that ends by performing an aging process that operates the lid heating means without operating the pan bottom heating means, and at the start of execution of the cake dough course, by the temperature detection means When the detected value is equal to or greater than a preset threshold value, the aging process is executed by skipping the baking process .

In the rice cooker according to the second aspect of the invention, the baking process is performed so that the temperature rises so that the temperature rise becomes steep, and the temperature rise rises more slowly than the first temperature rise process. A second temperature raising step for heating, and in the second temperature raising step, the energization rate to the pot bottom heating means is lowered and the energization rate to the lid heating means is increased.

According to these rice cookers, the cake dough course is a baking process that operates the pot bottom heating means that has a strong heating power, and after aging the dough inside and outside with good baking, it is an aging process that does not operate the pot bottom heating means Adjust the baking color on the surface of the dough and finish. Therefore, the baking color of the cake dough surface layer can be reliably adjusted without causing the cake dough to burn.

In addition, in the rice cooker of the first invention, at the start of execution of the cake dough course, if the detection value by the temperature detection means is equal to or greater than a preset threshold value, to perform the aging process, immediately after the end of the cake dough course, By performing again, additional heating can be performed. And since this additional heating is performed by the aging process which does not operate a pot bottom heating means, it can bake by adjusting the baking color of the upper surface according to liking, without scorching the bottom of dough.

Furthermore , in the rice cooker according to the second aspect of the invention, the baking process is performed so that the temperature rises so that the temperature rise becomes a steep gradient, and the temperature rises so that the temperature rise becomes a gentler gradient than the first temperature rise step. a configuration and a second heating step of, and, in the second heating step, lowering the duty ratio of the pan bottom heating means, since a configuration to increase the duty factor of the lid heating means, the surface layer of cake dough Heating to the inside (fire) can be ensured without causing burning.

  In the rice cooker of the present invention, after the cake dough course is baked with good baking inside and outside by baking treatment, the baking color of the surface of the dough is adjusted by aging treatment, so that the cake dough is burnt. The cake dough surface layer can be baked as a good baking color.

  In addition, when the cake dough course is continuously executed, an aging process is performed, so that the baking color of the upper surface can be adjusted according to preference without baking the bottom of the dough.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a rice cooker 10 according to an embodiment of the present invention. The rice cooker 10 includes a rice cooker body 12 that detachably accommodates the rice cooker 11 and a lid 20 that closes the upper end opening of the rice cooker body 12.

  The rice cooker body 12 is provided with a cylindrical inner cylinder 13 from an opening in which the rice cooker 11 is mounted, and the bottom of the inner cylinder 13 is closed by a heat shield plate 14. In addition, a heating plate 15 serving as a pot bottom heating means for heating the bottom of the rice cooking pot 11 is disposed inside the inner body 13. The heating plate 15 has a substantially bowl shape with a heater 16 disposed therein, and is formed of an aluminum material having good heat conductivity. Moreover, a through-hole 17 is provided in the center of the heating plate 15, and a temperature sensor for the pan, which is a first temperature detecting means, can detect the temperature of the rice cooking pot 11 placed on the top through the through-hole 17. 18 is arranged. Furthermore, on the upper side of the heating plate 15 outside the inner drum 13, a drum heater 19, which is a pan side heating means for heating the side portion of the rice cooking pan 11, is disposed.

  The lid 20 is rotatably attached to the rice cooker main body 12, and is provided on an upper plate 21, a lower plate 22 that closes a lower portion of the upper plate 21, and a lower surface of the lower plate 22. And an inner lid 23. The inner lid 23 is provided with a packing 24 that seals between the upper inner peripheral surface of the rice cooker 11. Further, an exhaust unit 25 for exhausting steam generated in the rice cooker 11 is provided between the upper plate 21 and the inner lid 23. Further, a lid heater 26 that is a lid heating means for heating the upper portion of the rice cooking pot 11 is disposed on the upper portion of the inner lid 23, and an upper space portion of a heated object such as rice that is the upper portion of the rice cooking pan 11. A lid temperature sensor 27, which is a second temperature detecting means for detecting the temperature, is provided.

  The rice cooker 10 is provided with an operation panel 28 on the front surface of the rice cooker body 12 for a user to input operating conditions and to display the operating state of the rice cooker 10.

  As shown in FIG. 2, the operation panel 28 has switches 29 to 35 as input means disposed around a central liquid crystal panel 36. Specifically, on the right side of the operation panel 28, a rice cooking switch 29 for executing a selected course as well as rice cooking, a reservation switch 30 for selecting a reservation function for cooking rice at a desired time, and a time Also, an upper switch 31 with black marks Δ and a lower switch 32 with black marks ▽ for setting the time are provided. Further, on the left side of the operation panel 28, a temporary switch 33 for stopping the selection of the operation or condition being executed, a menu switch 34 for selecting the condition, and a heat retention selection switch for selecting and executing the heat retention control (course). 35 is disposed.

  In the center of the operation panel 28, a liquid crystal panel 36, which is a segment display type display means for displaying by a driver built in the microcomputer 44 described later, is disposed. This liquid crystal panel 36 has a numerical display 37 for displaying the current time, the remaining time of the operation, a reservation display 38 for indicating the setting state of the reservation function, and a remaining time indicating that the numerical display 37 is the remaining time for the operation. A display 39 and a minute display 40, and a mark display 41 for indicating a selection state of a plurality of menus are provided. Further, at the lower part of the liquid crystal panel 36, a (normal) heat-retaining display 42 indicating a selection state of the heat-retaining course and a night (heat-retaining) display 43 are provided.

  And in this embodiment, as a menu, white rice and sushi, unwashed rice, white rice rapid, cooked rice, rice porridge, rice cake, brown rice, and cake (dough) are provided, and these characters are displayed. Is engraved next to each mark display 41.

  As shown in FIG. 3, the rice cooker 10 having the above-described configuration is controlled by a microcomputer 44, which is a control means, according to a program stored in a built-in storage means. Specifically, first, based on the operation of each of the switches 29 to 35, the condition is input and the display on the liquid crystal panel 36 is changed.

  When the menu switch 34 is operated in less than 1.5 seconds, as shown in FIG. 4A, the mark display 41 corresponding to white rice and sushi is turned on and the current time is displayed. As shown in 4 (B), the display is changed to a state in which the mark display 41 corresponding to non-washed rice is lit. Each time the menu switch 34 is operated, the menu selection state and display are changed in the order of white rice rapid, cooked rice, rice porridge, rice bran, brown rice, and cake, and the menu switch 34 is operated with the cake selected. When done, return to white rice and sushi. If the menu switch 34 is continuously operated for 1.5 seconds or longer, the menu selection state and display state are continuously changed in the above order until the operation is stopped.

  In this menu selection state, as shown in FIGS. 4A to 4C, the numerical value display 37 displays the current time from white rice and sushi to brown rice. On the other hand, as shown in FIG. 4D, in the cake selection state, the necessary time when executed in the standard process recommended in this cake dough control (course) is displayed. The rice cooker 10 of this embodiment is for 5 cups, and the standard time is 45 minutes.

  And in the selection state except the cake shown in FIG.4 (D), when rice cooking control is performed by operation of the rice cooking switch 29, each heater 16,19,26 will be set based on the detected value of each temperature sensor 18,27. A preheating step for controlling and absorbing water into the rice, a heating step for heating until the water in the rice cooker 11 boils, a boiling maintaining step for maintaining the boiling state, a cooking step for eliminating residual water in the rice cooker 11, and Then, after performing rice cooking control consisting of an uneven process of steaming rice cooked by heat storage, heat retention control is subsequently executed. Since this control is the same as in the prior art, detailed description is omitted.

  On the other hand, when the rice cooking switch 29 is operated in the cake selection state shown in FIG. 4 (D), the selected heating (execution) time is started. On the other hand, when the other switches 30, 33 to 35 except for the rice cooking switch 29, the upper switch 31 and the lower switch 32 are operated, the time setting of the cake dough course is stopped, and the operated switches 30, 33 to 35 are changed. Move to processing based on.

  When changing the execution time of this cake dough course, it is increased or decreased by operating the upper switch 31 or the lower switch 32 in the cake selection state shown in FIG. When the upper switch 31 is operated in less than 1.5 seconds, the execution time is incremented by 1 minute each time. If the operation is continued for 1.5 seconds or more, the execution time is continuously incremented every minute until the operation is stopped. The maximum execution time that can be set is 60 minutes. Further, when the lower switch 32 is operated in less than 1.5 seconds with the cake selected, the execution time is decremented by 1 minute each time. If the operation is continued for 1.5 seconds or longer, the execution time is continuously decremented every minute until the operation is stopped. The minimum time that can be set is 1 minute.

  In this execution time setting state, in the case of a short press operation of less than 1.5 seconds, the first notification sound is output each time. However, when the setting is changed to the standard setting time, a different second notification sound is output. On the other hand, in the case of a long press operation for 1.5 seconds or more, no notification sound is output even if the setting is changed except for the first. However, when the setting is changed at the standard setting time, the continuous setting change is paused for about 1.5 seconds, the second notification sound is output, the first notification sound is output, and the continuous setting change is resumed. .

  In the cake dough course of the present embodiment, a rough process that does not operate all the heaters 16, 19, and 26, a baking process that operates all the heaters 16, 19, and 26, and the heater 16 of the heating plate 15 operates. The maturation process for operating only the other heaters 19 and 26 is executed without causing them to end. That is, among the firing process and the aging process that require heating, the heater 16 of the heating plate 15 is operated only by the firing process, and the lid heater 26 and the body heater 19 are both operated.

  The baking process includes a temperature raising step for raising the temperature of the dough, a temperature adjustment step for fermenting the dough while maintaining heating to the rice cooking pot 11 at a preset temperature, and a baking step for baking the surface of the dough. . In addition, the aging treatment includes first and second unevenness steps for adjusting the baked color by heating the upper surface of the dough for a preset time and adjusting the swelling. And the standard time at the time of performing each said process, without changing execution time is 45 minutes as above-mentioned.

  However, even if the execution time is changed as described above, in the present embodiment, the cake dough control is executed by the same program as the standard setting time without changing the control of the baking process and the aging process. For this reason, if the time is set shorter than the standard setting time, the control is terminated when the time has elapsed. Incidentally, the standard time is set so as to be a standard baked color on the basis of the inventors. If the execution time is extremely reduced due to an erroneous setting, in this embodiment, the control ends during execution of the firing process. In this case, however, a desired burnt color cannot be expected at all. Therefore, when the execution time is reduced for the purpose of adjusting the baked color, the final second unevenness process of the aging process is shortened. On the other hand, if it is set longer than the standard setting time, the last second unevenness process of the aging process is continued (increased) by the time difference without changing the execution time of the baking process, and the control is terminated. When the cake dough course is started, if the detected value by the temperature sensors 18 and 27 is equal to or higher than a preset threshold value (80 ° C.), the second unevenness process of the aging process is executed for a set time.

  Next, the control of the cake dough course by the microcomputer 44 will be specifically described with reference to the flowchart of FIG. 5 and the time chart of FIG.

  In this cake dough course, the microcomputer 44 detects the temperature of the rice cooking pot 11 with the temperature sensors 18 and 27 in step S1. And it is detected by step S2 whether the temperature based on the detected value by the temperature sensor 18 for pots is less than 80 degreeC. If the temperature is lower than 80 ° C., the process proceeds to step S3. If the temperature is 80 ° C. or higher, the process proceeds to step S10.

  In step S2, it is detected whether the temperature based on the detection value by the lid temperature sensor 27 is less than 80 ° C. When the temperature is less than 80 ° C., the process proceeds to step S4, and when the temperature is 80 ° C. or more, the process proceeds to step S10.

  In step S4, a neglect process is executed. This negation process waits for a predetermined time (1 second in the present embodiment), stabilizes the air layer generated when the rice cooker 11 is accommodated and the flow associated with the accommodation shape, and cooks rice at the start. The temperature of the pan 11 can be accurately detected, and uniform heating can be performed. Note that the standby time is not limited to 1 second, and may be any time that can stabilize the flow of the air layer or the dough.

  When this negation process is completed, the firing process from step S5 to step S8 is executed.

  Specifically, first, in step S5, a first temperature raising step for raising the temperature so that the temperature rises steeply is executed. In this first temperature raising step, the heater 16 of the heating plate 15 is turned on / off at 20/30 msec, the lid heater 26 is turned on / off at 20/30 msec, and the body heater 19 is turned on / off at 5/30 msec. Thereby, the heating temperature by the heating plate 15 is 110 ° C., and the heating temperature by the lid heater 26 is 70 ° C. In addition, this 1st temperature rising process is complete | finished when the temperature detected by the temperature sensor 18 for pots for 2 minutes or becomes 80 degreeC, and transfers to the following process.

  When the first temperature raising step is completed, in step S6, a second temperature raising step is performed in which the temperature is raised so that the temperature rise has a gentler gradient than the first temperature raising step. In the second temperature raising step, the heater 16 of the heating plate 15 is turned on / off at 10/30 msec, the lid heater 26 is turned on / off at 30/30 msec, and the body heater 19 is turned on / off at 15/30 msec. That is, the energization rate to the heating plate 15 is lowered, and the energization rates to the body heater 19 and the lid heater 26 are increased. Thereby, the heating temperature by the heating plate 15 is 110 ° C., and the heating temperature by the lid heater 26 is 85 ° C. In addition, this 2nd temperature rising process is complete | finished when elapsed time becomes 20 minutes, and transfers to the following process.

  When the second temperature raising step is completed, in step S7, a temperature adjustment step is performed in which the inside of the dough is sufficiently heated and fermented. In this temperature adjustment process, the heater 16 of the heating plate 15 is turned on / off at 10/30 msec, the lid heater 26 is turned on / off at 10/30 msec, and the body heater 19 is turned on / off at 10/30 msec. Thus, the temperature is adjusted so that the heating temperature by the heating plate 15 is 110 ° C. and the heating temperature by the lid heater 26 is 95 ° C. In addition, this temperature control process is complete | finished when elapsed time becomes 15 minutes, and transfers to the following process.

  When the temperature adjustment process is completed, in step S8, a baking process is performed in which a predetermined baking color is imparted to the surface (top, bottom, and side surfaces) of the dough. In this baking process, the heater 16 of the heating plate 15 is turned on / off at 10/30 msec, the lid heater 26 is turned on / off at 30/30 msec, and the body heater 19 is turned on / off at 10/30 msec. Thus, heating is performed so that the heating temperature by the heating plate 15 is 110 ° C. and the heating temperature by the lid heater 26 is 130 ° C. This temperature adjustment process ends when the elapsed time is 3 minutes or when the temperature detected by the pan temperature sensor 18 reaches 118 ° C., and the process proceeds to the next process.

  When the baking process which is the last of the baking process is completed, the aging process of step S9 and step S10 is executed.

  Specifically, first, in step S9, a first unevenness process for adjusting the expansion and baking color of the dough is executed. In this first unevenness process, the heater 16 of the heating plate 15 is set to 0/30 msec to stop the operation, the lid heater 26 is turned on / off at 30/30 msec, and the body heater 19 is turned on / off at 20/30 msec. Thereby, it heats so that the temperature of the rice cooker 11 including the residual heat of the heating plate 15 may be 110 degreeC, and the heating temperature by the lid | cover heater 26 may be 130 degreeC. In addition, this temperature control process is complete | finished when elapsed time is 3 minutes, and transfers to the following process.

  When the first unevenness process is completed, in step S10, a second unevenness process for further adjusting the swelling and baking color of the dough is performed. In the second unevenness process, similarly to the first unevenness process, the heater 16 of the heating plate 15 is set to 0/30 msec to stop the operation, and the lid heater 26 is controlled to be turned on / off at 30/30 msec. On / off control is performed at 20/30 msec. Thereby, it heats so that the temperature of the rice cooker 11 including the residual heat of the heating plate 15 may be 110 degreeC, and the heating temperature by the lid | cover heater 26 may be 130 degreeC. In addition, this temperature control process is complete | finished when elapsed time is 3 minutes, and transfers to the following process.

  The above transition conditions are when the cake dough course is executed without changing the execution time, and when the execution time is changed, the control of the baking process and the aging process is changed as described above. Without being interrupted, the interruption is stopped when the execution time elapses, and when it is extended (increased), the second unevenness process is continued until the time elapses. . When the execution time is reduced for the purpose of adjusting the baked color, the final second unevenness process of the ripening process is shortened. Therefore, it is possible for the user to surely set the baking color adjustment according to the preference before execution, and the cake dough can be baked stably with the desired baking color.

  Incidentally, during the execution of the cake dough course, the liquid crystal panel 36 is decremented every minute as shown in FIG. 7A. When the control ends, as shown in FIG. 7B, the remaining time is displayed as 0 minutes and a notification sound indicating the end is output. Thereafter, as shown in FIG. 7C, “0” and the minute display 40 in the numerical display 37 are blinked. This display state is continued until the take-off switch 33 is operated or until 30 minutes have passed. When the take-off switch 33 is operated, as shown in FIG. 7D, the basic menu white rice and sushi mark display 41 are turned on, and the current time is displayed on the numerical display 37. On the other hand, when 30 minutes have elapsed, as shown in FIG. 7E, the numerical value display 37 and the minute display 40 are turned off, and the mark display 41 corresponding to the cake is blinked. This display state is continued until the take-off switch 33 is operated or the power cord is disconnected from the commercial power source. Further, when the upper switch 31 or the lower switch 32 is operated in the decrement display state of the remaining time, as shown in FIG. 7F, the current time is displayed by the numerical value display 37 only during the operation.

  Thus, in the rice cooker 10 of this invention, the control program for exclusive use for baking the cake dough different from rice cooking control is carried, and cooking other than rice cooking can be performed.

  And in this cake dough course, after baking the inside and outside of the dough with good baking by a baking process that operates the heating plate 15 having a strong heating power, the maturing process that does not operate the heating plate 15, Adjust the color to finish. Therefore, the baking color of the cake dough surface layer can be reliably adjusted without causing the cake dough to burn. In addition, since the bottom of the rice cooker 11 is heated by the heating plate 15, the dough can be heated by using heat storage, and energy saving can be achieved. In other words, the dough can be baked at a low running cost.

  In the firing process, first, in the first temperature raising step, the heating amount by the heating plate 15 having a strong heating power is increased, so that the temperature inside the rice cooker 11 can be raised so as to form a steep slope. . Thereafter, in the second temperature raising step, the amount of heating by the heating plate 15 is lowered, so that when the temperature reaches a preset temperature, excessive heating due to residual heat can be prevented. However, in the second temperature raising step, the heating amount of the other lid heater 26 and the body heater 19 is increased, so that partial burning and uneven burning can be suppressed while compensating for the insufficient heating amount. As a result, the inside of the cake dough can be reliably heated (fired) without causing scorching. Moreover, it is possible to prevent the fabric from cracking due to excessive heating of the upper surface of the fabric from the beginning.

  Moreover, in this baking process, the baking process which provides the baking color of cake dough is performed at the end. And in this baking process, since the heating plate 15 is always operated so far, the heating power is in a stable state, so that the baking can be easily adjusted without causing burning on the bottom side of the cake dough. .

  Further, the aging time can be increased or decreased before the cake dough course is executed, and the aging process is executed when the cooking pot 11 is equal to or more than a preset threshold at the start of the execution of the cake dough course. That is, the user can adjust and set the baked color in advance based on the experience of use, and perform additional heating by an aging process that finely adjusts the swelling and baked color when executed continuously immediately after the cake dough course is finished. be able to. Therefore, the baking color of the upper surface can be adjusted according to preference without baking the dough.

  In addition, the rice cooker 10 of this invention is not limited to the structure of the said embodiment, A various change is possible.

  For example, in the embodiment, in the case of additional heating, the aging process is performed. However, the transition process may be changed according to the temperature at the start.

  Moreover, although the said embodiment demonstrated using the rice cooker 10 which mounted the heating plate 15 which has the heater 16 as a pot bottom heating means which heats the bottom part of the rice cooking pot 11, the rice cooking pot 11 is energized by energizing a coil. Even if it is the rice cooker 10 which carries out induction heating, the substantially the same effect | action and effect can be acquired by applying the said cake dough course.

  Furthermore, in the said embodiment, although the rice cooker 10 which arrange | positioned the trunk | drum heater 19 which is a pan side part heating means around the inner cylinder 13 was applied, the rice cooker 10 which does not mount this trunk | drum side part heating means is the same. Applicable.

It is a schematic sectional drawing which shows the rice cooker of this invention. It is a front view of an operation panel. It is a block diagram of a rice cooker. (A)-(D) are front views which show the display change of a liquid crystal panel at the time of operating a menu switch. It is a flowchart which shows control of the cake dough course by a microcomputer. It is a time chart which shows the control of FIG. (A)-(F) are front views which show the display change of the liquid crystal panel during cake dough course execution.

Explanation of symbols

10 ... Rice cooker 11 ... Rice cooker
12 ... Rice cooker body 15 ... Heating plate 16 ... Heater (pot bottom heating means)
18 ... Pan temperature sensor (temperature detection means)
19 ... Body heater (pan side heating means)
20 ... Lid 26 ... Lid heater (lid heating means)
27. Temperature sensor for lid (temperature detection means)
42 ... Microcomputer (control means)

Claims (2)

A rice cooker body that houses the rice cooker, a pot bottom heating means that heats the bottom of the rice cooker, a lid heating means that heats the top of the rice cooker, and a temperature detection means that detects the temperature of the rice cooker. In the rice cooker that performs the rice cooking control by controlling each heating means based on the detection value of the temperature detecting means,
After performing the baking process to operate each heating means, providing a cake dough course that ends by executing the aging process to operate the lid heating means without operating the pot bottom heating means ,
At the start of execution of the cake dough course, if the detected value by the temperature detecting means is greater than or equal to a preset threshold value, the baking process is skipped and the ripening process is performed. vessel. A rice cooker body that houses the rice cooker, a pot bottom heating means that heats the bottom of the rice cooker, a lid heating means that heats the top of the rice cooker, and a temperature detection means that detects the temperature of the rice cooker. In the rice cooker that performs the rice cooking control by controlling each heating means based on the detection value of the temperature detecting means,
After performing the baking process to operate each heating means, providing a cake dough course that ends by executing the aging process to operate the lid heating means without operating the pot bottom heating means ,
The firing treatment includes a first temperature raising step for raising the temperature so that the temperature rise has a steep slope, and a second temperature raising step for raising the temperature so that the temperature rise has a gentler gradient than the first temperature raising step. And
In the second temperature raising step, a rice cooker characterized in that the energization rate to the pot bottom heating means is lowered and the energization rate to the lid heating means is increased .

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