JP7394351B2 - rice cooker - Google Patents

Description

The present invention relates to a rice cooker equipped with a superheated steam generator that generates steam exceeding 100°C (hereinafter referred to as superheated steam).

Conventionally, as this type of rice cooker, for example, the rice cooker described in Patent Document 1 (Japanese Unexamined Patent Publication No. 2016-44880) is known. Patent Document 1 describes a water container that stores water, a water container heating device that heats the water container, and a water container that heats steam generated from the water container to generate superheated steam exceeding 100°C, and then heats the superheated steam in a pot. A rice cooker is disclosed that includes a superheated steam generator that supplies steam to the inside of the rice cooker.

JP2016-44880A

The rice cooker of Patent Document 1 still has room for improvement in terms of increasing the temperature of superheated steam supplied into the pot.

An object of the present invention is to provide a rice cooker that can raise the temperature of superheated steam supplied into a pot in order to solve the above problems.

The rice cooker according to the present invention includes a pot;
a water container containing water;
a water container heating device that heats the water container;
A superheated steam generator that heats the steam generated from the water container to generate superheated steam exceeding 100°C and supplies the superheated steam into the pot;
an inlet-side temperature detection section that is disposed on the inlet side of the superheated steam generator that takes in the steam generated from the water container, and that detects the temperature of the steam;
an exit-side temperature detection section that is arranged on the exit side of the superheated steam generator that supplies the superheated steam into the pot and detects the temperature of the superheated steam;
a control unit that controls operations of the water container heating device and the superheated steam generator;
Equipped with
The control unit performs a preheating step in which the superheated steam generator performs heating but does not supply the superheated steam into the pot, and takes in steam generated from the water container and supplies the superheated steam into the pot. The superheated steam generator is controlled to perform the supply step, and when the temperature detected by the inlet side temperature detection section reaches a first threshold temperature of 100° C. or higher in the preheating step, the first threshold temperature is The heating by the superheated steam generator is weakened so as not to exceed the temperature, and when the temperature detected by the inlet side temperature detection section reaches a second threshold temperature higher than the first threshold temperature in the supply step, the second threshold temperature controlling the heating by the superheated steam generator so as not to exceed
It is configured as follows.

According to the rice cooker according to the present invention, the temperature of superheated steam supplied into the pot can be made higher.

1 is a schematic cross-sectional view of a rice cooker including a superheated steam generator according to an embodiment of the present invention. FIG. 2 is a plan view showing the lid of the rice cooker in FIG. 1 with some parts removed. FIG. 1 is a side view of a superheated steam generator according to an embodiment of the present invention. 1 is a plan view of a superheated steam generator according to an embodiment of the present invention. FIG. 1 is an exploded perspective view of a superheated steam generator according to an embodiment of the present invention. 5 is a sectional view taken along the line A1-A1 in FIG. 4. FIG. It is a graph which shows the change of the detection temperature or threshold temperature of various temperature detection parts when performing an example of a rice cooking process using the rice cooker which concerns on this embodiment. It is a graph which shows the change of the detection temperature or threshold temperature of various temperature detection parts when performing an example of a rice cooking process using the rice cooker which concerns on this embodiment. In the rice cooker of FIG. 1, it is a perspective view which shows an example of the structure which mounts IGBT on the board|substrate.

(Findings that formed the basis of the present invention)
The inventors of the present invention have made the following findings as a result of intensive studies to increase the temperature of superheated steam supplied into the pot.

In a conventional rice cooker, the rice cooking process mainly consists of four steps: a soaking process, a temperature raising process, a boiling maintenance process, and a steaming process. The superheated steam generator is configured to supply superheated steam into the pot during the steaming process. It is known that the higher the temperature of the superheated steam supplied into the pot, the better the taste of the rice will be. In conventional rice cookers, the temperature of superheated steam generated by a superheated steam generator is 130°C to 220°C.

In addition, in conventional rice cookers, when heating is performed by a superheated steam generator during the preheating process, hot air with a temperature higher than 100°C (for example, 130°C) is generated in the superheated steam generator, and the superheated steam The heat load on the generator and parts placed around it increases. If this high heat load continues when superheated steam is not supplied into the pot, it will lead to deterioration of the superheated steam generator and its related parts. For this reason, conventional rice cookers are equipped with an inlet-side temperature detection section on the inlet side of the superheated steam generator, and when the detected temperature of the inlet-side temperature detection section reaches a threshold temperature (for example, 130 degrees Celsius), the water container is heated. The device and the superheated steam generator, or the heating by the superheated steam generator is configured to be stopped.

However, with this configuration, when superheated steam exceeding 220°C is generated, the temperature of the superheated steam generator and its surrounding parts increases due to the heat generated by the superheated steam generator during preheating of the superheated steam generator, and the superheated steam It becomes impossible to continue the operation that causes the problem. For this reason, in conventional rice cookers, it is difficult to increase the temperature of superheated steam supplied into the pot 2 higher than 220°C.

Therefore, as a result of intensive study, the inventors of the present invention determined that the temperature of superheated steam could be raised to a higher temperature ( For example, we have found that it is possible to raise the temperature up to 250°C. By increasing the temperature of superheated steam, the taste can be further enhanced. Based on this new knowledge, the present inventors have arrived at the following invention.

According to the first aspect of the invention, a pot;
a water container containing water;
a water container heating device that heats the water container;
A superheated steam generator that heats the steam generated from the water container to generate superheated steam exceeding 100°C and supplies the superheated steam into the pot;
an inlet-side temperature detection section that is disposed on the inlet side of the superheated steam generator that takes in the steam generated from the water container, and that detects the temperature of the steam;
an exit-side temperature detection section that is arranged on the exit side of the superheated steam generator that supplies the superheated steam into the pot and detects the temperature of the superheated steam;
a control unit that controls operations of the water container heating device and the superheated steam generator;
Equipped with
The control unit performs a preheating step in which the superheated steam generator performs heating but does not supply the superheated steam into the pot, and takes in steam generated from the water container and supplies the superheated steam into the pot. The superheated steam generator is controlled to perform the supply step, and when the temperature detected by the inlet side temperature detection section reaches a first threshold temperature of 100° C. or higher in the preheating step, the first threshold temperature is The heating by the superheated steam generator is weakened so as not to exceed the temperature, and when the temperature detected by the inlet side temperature detection section reaches a second threshold temperature higher than the first threshold temperature in the supply step, the second threshold temperature controlling the heating by the superheated steam generator so as not to exceed
Provide a rice cooker.

According to a second aspect of the present invention, there is provided the rice cooker according to the first aspect, wherein the control unit sets the first threshold temperature to a specific temperature within a range of 100°C or more and 120°C or less.

According to the third aspect of the present invention, the rice cooking according to the first or second aspect sets the second threshold temperature to a specific temperature within a range of 120° C. or higher and 150° C. or lower. Provide utensils.

According to the fourth aspect of the present invention, the water container temperature detection section further includes a water container temperature detection section that detects the temperature of the water container, and the control section is configured such that the temperature detected by the water container temperature detection section in the preheating step is a third threshold temperature. The rice cooker according to any one of the first to third aspects is provided, in which the first threshold temperature is increased when the temperature exceeds the temperature.

According to the fifth aspect of the present invention, when the temperature detected by the water container temperature detection unit in the preheating step is lower than the third threshold temperature, the control unit sets the first threshold temperature to 100°C or more and less than 110°C. and when the temperature detected by the water container temperature detection unit becomes equal to or higher than the third threshold temperature in the preheating step, the first threshold temperature is set to a range of 110°C or more and 120°C or less. The rice cooker according to the fourth aspect is provided, wherein the rice cooker is set to a specific temperature within the rice cooker.

According to the sixth aspect of the present invention, when the temperature detected by the outlet side temperature detection unit reaches a fourth threshold temperature of 100° C. or higher in the preheating step, the control unit is configured to exceed the fourth threshold temperature. a fourth or third step, wherein the heating by the superheated steam generator is weakened so as not to occur, and when the temperature detected by the water container temperature detection section exceeds the third threshold temperature in the preheating step, the fourth threshold temperature is increased; The rice cooker according to the fifth aspect is provided.

According to the seventh aspect of the present invention, the control unit controls the overheating so that the temperature detected by the outlet side temperature detection unit becomes equal to or lower than a fifth threshold temperature when a predetermined period of time has elapsed in the supply step. The rice cooker according to any one of the first to sixth aspects is provided, in which the heating by the steam generator is weakened, and after a predetermined period has elapsed, the heating by the water container heating device is stopped.

According to the eighth aspect of the present invention, the control unit weakens the heating by the superheated steam generator in the supply step, and after the temperature detected by the outlet side temperature detection unit falls to a fifth threshold temperature or less, Provided is a rice cooker according to any one of the first to sixth aspects, in which heating by the water container heating device is stopped.

Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to this embodiment. Further, in the drawings, substantially the same members are designated by the same reference numerals.

In addition, for convenience of explanation, terms such as "up" and "down" indicating directions will be used assuming the state during normal use, but this does not limit the usage state of the rice cooker according to the present invention. It doesn't mean anything.

《Embodiment》
The overall configuration of a rice cooker according to an embodiment of the present invention will be described using FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view of a rice cooker according to an embodiment of the present invention. FIG. 2 is a plan view showing the lid of the rice cooker shown in FIG. 1 with some parts removed.

As shown in FIG. 1, the rice cooker according to the present embodiment includes a rice cooker main body 1 having a substantially bottomed cylindrical shape in which a pot storage section 1a is formed, and a rice cooker body 1 that is housed in the pot storage section 1a, and that can store water and rice. The pot 2 is equipped with a pot 2 in which food including food can be placed. A lid 3 having a hollow structure that can open and close the upper opening of the rice cooker body 1 is attached to the top of the rice cooker body 1. On the inside of the lid 3 (the side that covers the opening of the pot 2), a substantially disc-shaped inner lid 4 that can seal the upper opening of the pot 2 is removably attached.

The pot storage section 1a of the rice cooker main body 1 is composed of an upper frame 1b and a coil base 1c. The upper frame 1b includes a cylindrical portion 1ba arranged so as to leave a gap with respect to the side wall of the pot 2 stored therein, and a cylindrical portion 1ba that protrudes outward from the top of the cylindrical portion 1ba and extends inside the upper opening of the rice cooker main body 1. A flange portion 1bb that fits into the peripheral portion is provided. Further, a water container storage portion 1bc for storing the water container 5 is formed in the flange portion 1bb.

The water container 5 is a cylindrical container with a bottom that stores water for generating steam. A water container heating device 6 for heating the water container 5 is attached to the outer peripheral surface of the water container storage portion 1bc. In this embodiment, the water container heating device 6 is configured to inductively heat the water container 5 using a heating coil. Note that the water container heating device 6 may be configured to heat the water container 5 with a heater. When the water container heating device 6 heats the water container 5, the water in the water container 5 is boiled and steam at about 100° C. is generated. Further, an opening is provided on the side of the water container storage portion 1bc. A water container temperature detection section 51 for measuring the temperature of the water container 5 is arranged in the opening part so as to be able to come into contact with the side of the water container 5 stored in the water container storage section 1bc.

The coil base 1c is formed into a bottomed cylindrical shape corresponding to the shape of the lower part of the pot 2, and its upper part is attached to the lower end of the cylindrical part 1ba of the upper frame 1b. A pot heating device 7 that heats the pot 2 (induction heating) is attached to the outer peripheral surface of the coil base 1c. The pot heating device 7 includes an inner-bottom heating coil 7a and an outer-bottom heating coil 7b. The bottom heating coil 7a is arranged to face the periphery of the center of the bottom of the pot 2 via the coil base 1c. The outside heating coil 7b is arranged so as to face the bottom corner of the pot 2 via the coil base 1c. A plurality of ferrites 8 are arranged below the bottom heating coil 7a to guide the magnetic flux generated by the bottom heating coil 7a inside to prevent leakage of the magnetic flux.

An opening is provided in the center of the bottom of the coil base 1c. A pot temperature detection section 9 for measuring the temperature of the pot 2 is arranged in the opening so as to be able to come into contact with the bottom of the pot 2 stored in the pot storage section 1a. Since the temperature of the pot 2 is approximately the same as the temperature of the food in the pot 2, the temperature of the food in the pot 2 can be known by the pot temperature detection section 9 detecting the temperature of the pot 2.

The lid 3 includes an upper outer shell member 3a and a lower outer shell member 3b that constitute the outer shell of the lid 3. The lid 3 also includes a hinge shaft 3A. The hinge shaft 3A is a shaft for opening and closing the lid 3, and is rotatably held at both ends by the upper frame 1b of the rice cooker main body 1. A through hole 3c is provided in the lid 3 so as to penetrate near the center thereof in the thickness direction of the lid 3. The upper end of the through hole 3c communicates with the bottom of a recess 3aa provided in the upper outer shell member 3b. A steam cylinder 10 is detachably attached to the recess 3aa.

An annular packing 11 is attached around the through hole 3c of the lid 3 on the inner lid 4 side. The packing 11 is provided so as to be in close contact with the periphery of the steam exhaust hole 4a provided in the inner cover 4 when the inner cover 4 is attached to the cover 3. A steam escape hole 10a is provided in the upper wall of the steam cylinder 10 so that excess steam in the pot 2 supplied into the recess 3aa through the steam exhaust hole 4a and the through hole 3c can be discharged to the outside of the rice cooker. ing.

An annular packing 12 is attached to the surface of the outer periphery of the inner lid 4 facing the pot 2. The packing 12 is provided so as to be in close contact with the flange portion of the pot 2 when the lid 3 is in the closed state.

Further, inside the lid 3, a superheated steam generator 13 is provided which heats the steam generated from the water container 5 to generate superheated steam exceeding 100° C., and supplies the superheated steam into the pot 2. . The superheated steam generator 13 is attached to the lower outer shell member 3b of the lid 3 using fastening members such as screws. The structure of the superheated steam generator 13 will be explained in detail later.

In addition, the lid 3 has a display section 21 such as a liquid crystal display that displays various information such as rice cooking courses and rice cooking times, and a display section 21 that displays various information such as rice cooking courses, rice cooking times, etc. An operation unit (not shown) is provided that allows selection of rice cooking courses. The operation unit is composed of a plurality of buttons, such as a rice cooking start button, so that in addition to selecting a rice cooking course, instructions can be given to start, cancel, and reserve rice cooking. The user can refer to the display content on the display section 21, select a specific rice cooking course using the operation section, and instruct the start of rice cooking.

A control section 22 is mounted inside the rice cooker main body 1. The control unit 22 includes a storage unit that stores a plurality of rice cooking sequences for cooking rice. Here, "rice cooking sequence" refers to the process of sequentially performing each step of the rice cooking process, which mainly consists of four steps: soaking in water, raising temperature, maintaining boiling, and steaming. A rice cooking procedure in which heating output etc. are predetermined. Each rice cooking sequence corresponds to one of a plurality of rice cooking courses. The control section 22 controls the driving of each section and each device based on the rice cooking course selected by the operation section, the detected temperature of each temperature detection section, etc., and executes the rice cooking process. Further, the control unit 22 controls the operations of the water container heating device 6 and the superheated steam generator 13. Control by the control unit 22 will be explained in detail later.

Next, the structure of the superheated steam generator 13 will be explained in more detail with reference to FIGS. 3 to 6. FIG. 3 is a side view of the superheated steam generator 13. FIG. 4 is a plan view of the superheated steam generator 13. FIG. 5 is an exploded perspective view of the superheated steam generator 13. FIG. 6 is a sectional view taken along line A1-A1 in FIG.

As shown in FIG. 5, the superheated steam generator 13 includes a pipe 31, a heat exchanger 32 disposed in the pipe 31, a coil bobbin 33 disposed so as to surround the outer peripheral surface of the pipe 31, and a coil bobbin 33 disposed so as to surround the outer peripheral surface of the pipe 31. and an induction heating coil 34 disposed on the outer circumferential surface of.

The pipe 31 is made of a non-magnetic metal such as austenitic stainless steel so that both the pipe 31 and the heat exchanger 32 are heated by induction when the induction heating coil 34 is driven. By induction heating both the pipe 31 and the heat exchanger 32, the steam taken into the pipe 31 is heated to become superheated steam exceeding 100°C.

An intake pipe 35 that supplies steam into the pipe 31 is connected to one end of the pipe 31 . The intake pipe 35 is provided to communicate with the inside of the water container 5 when the lid 3 is in the closed state, and to guide steam generated inside the water container 5 into the pipe 31. An intake pipe suppressing member 36 is provided at the connection portion between the intake pipe 35 and the pipe 31. As shown in FIGS. 3 and 4, the intake pipe restraining member 36 is attached to one end of the coil bobbin 33 to prevent the intake pipe 35 from coming off the pipe 31. An annular packing 14 is attached between the lower outer shell member 3b of the lid 3 and the water container 5, as shown in FIG. The packing 14 is provided so as to be in close contact with the flange portion of the water container 5 when the lid 3 is in the closed state.

Note that a check valve 17 is provided in the passage 16 that connects the lower outer shell member 3b above the water container 5 and the intake pipe 35. The check valve 17 has a ball 17a that falls under its own weight and an orifice-shaped valve seat 17b. When the pressure inside the water container 5 increases, the ball 17a floats and the check valve 17 changes from the closed state to the open state. When the pressure inside the pot 2 increases, the ball 17a lowers and comes into close contact with the valve seat 17b, thereby closing the check valve 17, so that backflow to the water container 5 can be suppressed.

As shown in FIG. 1, the other end of the pipe 31 is bent toward the inside of the pot 2 and communicates with the inside of the pot 2 through a superheated steam exhaust hole 4b provided in the inner lid 4. A superheated steam exhaust fitting 37 is attached to the other end of the pipe 31, as shown in FIGS. 5 and 6. The superheated steam in the pipe 31 is discharged into the pot 2 through the superheated steam discharge fitting 37 and the superheated steam discharge hole 4b.

Further, as shown in FIG. 6, an annular packing 15 is disposed at the other end of the pipe 31 so as to cover the other end and the superheated steam exhaust fitting 37. As shown in FIG. 1, the packing 15 is provided so as to tightly fit around the superheated steam exhaust hole 4b of the inner lid 4 when the lid 3 is in the closed state. The outer peripheral portion of the packing 15 is held by a pipe restraining member 38. The pipe restraining member 38 is attached to the other end of the coil bobbin 33. A packing 39 is fitted onto the outer peripheral surface of the pipe restraining member 38. This packing 39 brings the packing 15 into close contact with the pipe suppressing member 38 and the pipe 31.

As shown in FIGS. 5 and 6, the heat exchanger 32 includes a core rod 32a and a spiral body 32b spirally wound around the outer peripheral surface of the core rod 32a. At least one of the core rod 32a and the spiral body 32b is made of metal so as to be induction heated by driving the induction heating coil 34. The core rod 32a is disposed within the pipe 31 coaxially with the central axis of the pipe 31. In addition, in FIG. 6, the core rod 32a and the spiral body 32b are shown in a side view.

Further, as shown in FIG. 6, the pipe 31 is provided with caulked portions 31a near both ends of the heat exchanger 32. Movement of the heat exchanger 32 is restricted by these caulked portions 31a. An outlet side temperature detection section 41 that detects the temperature of the superheated steam generated within the pipe 31 is in contact with the caulking section 31a on the superheated steam discharge side (exit side) (see FIGS. 4 and 5). That is, the outlet side temperature detection section 41 is arranged on the exit side of the superheated steam generator 13 that supplies superheated steam into the pot 2, and is configured to detect the temperature of the superheated steam. On the other hand, an inlet side temperature detection part 42 (see FIGS. 4 and 5) that detects the temperature of the steam taken into the pipe 31 is in contact with the caulked part 31a on the steam intake side (inlet side). That is, the inlet side temperature detection section 42 is arranged on the inlet side of the superheated steam generator 13 that takes in the steam generated from the water container 5, and is configured to detect the temperature of the steam.

The coil bobbin 33 is made of an insulating member such as resin. The coil bobbin 33 is provided with a space between it and the pipe 31, as shown in FIG. Thereby, even if the pipe 31 is heated by induction and generates heat, it is possible to prevent the coil bobbin 33 from melting due to the heat. Further, at this time, it is also possible to eliminate the need for placing a heat insulating material between the coil bobbin 33 and the pipe 31.

The induction heating coil 34 is arranged on the outer circumferential surface of the coil bobbin 33 so as to be divided into at least two (two in this embodiment). The induction heating coil 34 usually has the property that the heating power is highest at the center, and the heating power decreases as the distance from the center increases. By dividing and arranging the induction heating coil 34 into two or more, it is possible to shorten the distance from the center portion to both ends of the divided induction heating coil. For example, when the length of the induction heating coil 34 is 50 mm, the distance from the center portion to both ends of the induction heating coil 34 is 25 mm. On the other hand, when the induction heating coil 34 is divided into two, the distance from the center to both ends of the divided induction heating coil is 12.5 mm. Thereby, it is possible to suppress a decrease in the heating power by the induction heating coil 34, and it is possible to improve the average heating power by the induction heating coil 34.

Next, the operation of the rice cooker according to this embodiment will be explained. FIG. 7 is a graph showing changes in detected temperatures DT9 and DT51 or threshold temperatures T41 and T42 of various temperature detection units when an example of the rice cooking process is performed using the rice cooker according to the present embodiment. In FIG. 7, changes in the temperature DT9 detected by the pan temperature detection section 9 are shown by dotted lines. Further, a change in the temperature DT51 detected by the water container temperature detection section 51 is shown by a chain line. Further, a change in the threshold temperature T41 of the outlet side temperature detection section 41 is shown by a two-dot chain line. Further, a change in the threshold temperature T42 of the inlet side temperature detection section 42 is shown by a solid line.

In the present embodiment, the control unit 22 performs a preheating step in which the superheated steam generator 13 performs heating but does not supply superheated steam into the pot 2, and a preheating step in which superheated steam is not supplied into the pot 2 by taking in steam generated from the water container 5 to supply superheated steam in the pot 2. The superheated steam generator 13 is controlled to carry out the supply step of supplying. The preheating process corresponds to a submersion process, a temperature raising process, and a boiling maintenance process. The feeding process corresponds to the first half of the steaming process.

First, the user sets the pot 2 containing food to be cooked including rice and water into the pot storage section 1a, and sets the water container 5 containing water into the water container storage section 1bc. Thereafter, when the user selects a rice cooking course using an operation unit (not shown) and instructs to start rice cooking, the rice cooking process is started under the control of the control unit 22. When the rice cooking process is started, first, a soaking process and a preheating process are started.

The soaking process is a process in which the rice is soaked in water at a temperature lower than the gelatinization temperature to allow the rice to absorb water in advance so that the center of the rice can be sufficiently gelatinized in the subsequent steps. In this submersion step, the control unit 22 raises the temperature of the water in the pot 2 to near the temperature at which gelatinization of rice begins (for example, about 60°C), and then maintains the temperature after the temperature rise. , controls the pot heating operation of the pot heating device 7 based on the detected temperature DT9 of the pot temperature detection section 9. This promotes water absorption in the rice. Further, in this submergence step, the control unit 22 starts a preheating step of driving the water container heating device 6 to preheat the water in the water container 5. As a result, the detected temperature DT51 of the water container temperature detection section 51 starts to gradually rise. When the temperature detected by the inlet side temperature detection unit 42 reaches a threshold temperature T42a (first threshold temperature) of 100° C. or higher in the preheating process, the control unit 22 controls the superheated steam generator 13 so as not to exceed the threshold temperature T42a. control to weaken (for example, stop) the heating caused by In this embodiment, the control unit 22 sets the threshold temperature T42a to a specific temperature (for example, 110°C) within a range of 100°C or more and 120°C or less. In addition, it is preferable that the preheating process is performed using electric power that is not used by the pot heating device 7. The submersion process uses less power by the pot heating device 7 compared to the temperature raising process and the boiling maintenance process. For this reason, it is preferable that the preheating step is started during the submersion step. When a predetermined time period has elapsed from the start of the soaking process according to the selected rice cooking course, the process moves to the temperature raising process.

The temperature raising step is a step of heating the pot 2 at once over high heat to bring the water in the pot 2 to a boiling state (approximately 100° C.). In this temperature raising step, the control unit 22 controls the pot heating device 7 to rapidly heat the pot 2 and bring the water in the pot 2 to a boiling state. The time required for the temperature raising step varies depending on the amount of rice cooked (the amount of food placed in the pot 2). Therefore, the amount of cooked rice can be automatically determined based on the time required for the temperature raising step. The control unit 22 performs subsequent steps based on the amount of cooked rice determined in the temperature raising step. In the temperature raising process, when a steam temperature sensor (not shown) detects a predetermined temperature (for example, the boiling point of water), the process moves to the boiling maintenance process.

The boiling maintenance step is a step of maintaining the boiling state of the water in the pot 2 to gelatinize the rice starch and raise the degree of gelatinization to about 50% to 80%. In this boiling maintenance step, the control section 22 controls the pot heating device 7 based on the detected temperature DT9 of the pot temperature detection section 9 so as to maintain the boiling state of the water in the pot 2.

In the boiling maintenance process, water is continuously boiled, so a large amount of steam is generated. This steam passes through the steam exhaust hole 4a, through hole 3c, and steam escape hole 10a of the inner lid 4 and is released to the outside of the rice cooker (see FIG. 1). As a result, when most of the water in the pot 2 disappears, the temperature of the bottom surface of the pot 2 rises to 100° C. or more. When it is detected that the detected temperature DT9 of the pot temperature detection section 9 has reached a predetermined temperature exceeding 100°C (for example, 130°C), the steaming process is started. When the temperature detected by the outlet side temperature detection unit 41 reaches the threshold temperature T41a in the boiling maintenance process that is the preheating process, the control unit 22 weakens the heating by the superheated steam generator 13 so as not to exceed the threshold temperature T41a ( (for example, to stop). In this embodiment, the control unit 22 sets the threshold temperature T41a to a temperature higher than the predetermined temperature (for example, 140° C.).

The steaming process uses preheating to evaporate excess moisture and raises the degree of gelatinization of rice to nearly 100%. In this steaming process, the control unit 22 controls the superheated steam generator 13 to heat the steam generated from the water container 5 to generate superheated steam exceeding 100°C, and supplies the superheated steam into the pot 2. Perform the supply process. In this embodiment, the temperature of the superheated steam supplied into the pot 2 is 250°C±25°C. When the temperature detected by the outlet side temperature detection unit 41 reaches a threshold temperature T41b higher than the threshold temperature T41a in the supply process, the control unit 22 weakens the heating by the superheated steam generator 13 so as not to exceed the threshold temperature T41b (for example, , stop). In this embodiment, the control unit 22 sets the threshold temperature T41b to a temperature corresponding to the superheated steam supplied into the pot 2 (for example, 250° C.±25° C.). Note that the timing at which the control unit 22 switches from the threshold temperature T41a to the threshold temperature T41b may be a little earlier (for example, several tens of seconds) earlier than the start of the supply process, as shown in FIG. Thereby, high-temperature superheated steam can be supplied into the pot 2 immediately after the start of the supply process.

Furthermore, if heating by the water container heating device 6 is stopped immediately after the supply process ends, an overshoot may occur in which the temperature of the superheated steam generator 13 suddenly increases due to the heat accumulated in the superheated steam generator 13 until then. Therefore, in the present embodiment, the control unit 22 changes the threshold temperature T41 of the outlet side temperature detection unit 41 from the threshold temperature T41b to the threshold temperature DT41c (fifth threshold temperature) before stopping the heating by the water container heating device 6. control to lower the level. That is, the control unit 22 weakens the heating by the superheated steam generator 13 in the supply process and stops the heating by the water container heating device 6 after the temperature detected by the outlet side temperature detection unit 41 falls to below the threshold temperature T41c. control. The threshold temperature T41c is a temperature lower than the threshold temperature T41b, for example, 200°C. This makes it possible to suppress overshoot. Alternatively, if a predetermined time has elapsed since the temperature detected by the outlet side temperature detector 41 was set to the threshold temperature T41b, the control unit 22 controls the temperature detected by the outlet side temperature detector 41 to be equal to or lower than the threshold temperature T41c. The heating by the superheated steam generating means 13 may be weakened so that the temperature increases. Thereafter, the control unit 22 may stop the heating by the water container heating device 6 after a predetermined period has elapsed. This makes it possible to suppress overshoot.

In addition, when the temperature detected by the inlet side temperature detection unit 42 reaches a threshold temperature T42b (second threshold temperature) higher than the threshold temperature T42a in the supply process, the control unit 22 controls the superheated steam so that the temperature does not exceed the threshold temperature T42b. The heating by the generator 13 is controlled to be weakened (for example, stopped). In this embodiment, the control unit 22 sets the threshold temperature T42b to a specific temperature (for example, 140°C) within a range of 120°C or more and 150°C or less. Note that the timing at which the control unit 22 switches from the threshold temperature T42a to the threshold temperature T42b may be a little earlier (for example, several tens of seconds) earlier than the start of the supply process, as shown in FIG. Thereby, high-temperature superheated steam can be supplied into the pot 2 immediately after the start of the supply process. After the supply process is finished, when the temperature detected by the inlet side temperature detection unit 42 reaches a threshold temperature T42c, the control unit 22 weakens the heating by the superheated steam generator 13 so as not to exceed the threshold temperature T42c (for example, stops the heating). control). In this embodiment, the threshold temperature T42c may be the same as or different from the threshold temperature T42a.

When a predetermined time has elapsed from the start of the steaming process according to the selected rice cooking course, the steaming process is ended (that is, the rice cooking process is ended).

According to the rice cooker according to the present embodiment, the control unit 22 performs a preheating process in which superheated steam is not supplied into the pot 2 while heating is performed by the superheated steam generator 13, and in which steam generated from the water container 5 is taken in. The superheated steam generator 13 is controlled to perform a supply step of supplying superheated steam into the pot 2. Further, the control unit 22 controls the heating by the superheated steam generator 13 to be weakened when the temperature detected by the inlet side temperature detection unit 42 reaches the threshold temperature T42a in the preheating process. Thereby, the temperature of the superheated steam can be increased before the supply step while reducing the heat load on the superheated steam generator 13 and its related components. Furthermore, the control unit 22 controls the heating by the superheated steam generator 13 to be weakened when the temperature detected by the inlet side temperature detection unit 42 reaches the threshold temperature T42b in the supply process. That is, the control unit 22 controls to change the threshold temperature T42 between the preheating process and the supply process. Thereby, the temperature of the superheated steam supplied into the pot 2 can be made higher.

Note that the present invention is not limited to the above embodiments, and can be implemented in various other ways. For example, in the above description, the threshold temperature T42a is switched to the threshold temperature T42b at a timing a little earlier than the start of the supply process, but it is also possible to switch from the threshold temperature T42a to the threshold temperature T42b depending on the temperature of the water in the water container 5. good. For example, when the temperature of the water in the water container 5 is high (for example, 90° C. or higher), steam is generated. If this steam enters the superheated steam generator 13, dew condensation may occur within the superheated steam generator 13. The superheated steam generator 13 generates superheated steam by superheating steam at 100°C or higher, so when supplying steam (steam) below 100°C into the pot 2, there is no need to heat it. . For this reason, if heating is performed by the superheated steam generator 13 just to prevent the generation of dew water, extra electric power may be required. Moreover, the deterioration of parts installed around the superheated steam generator 13 may be affected. For example, if the temperature detected by the water container temperature detection unit 51 is less than 70° C., the temperature of the superheated steam generator 13 is low because preparations for generating saturated steam are not yet completed. Therefore, as shown in FIG. 8, when the detected temperature DT51 of the water container temperature detection section 51 becomes equal to or higher than the threshold temperature DT51a (third threshold temperature) in the preheating process, the control section 22 increases the threshold temperature T42a ( For example, the threshold temperature T42b) may be used. Further, in the preheating process, when the detected temperature DT51 of the water container temperature detection unit 51 is less than the threshold temperature DT51a (third threshold temperature), the control unit 22 sets the threshold temperature T42a to a specific temperature within the range of 100°C or more and less than 110°C. It may also be set to the temperature. Furthermore, the control unit 22 sets the threshold temperature T42a to a specific temperature within the range of 110°C or more and less than 130°C when the detected temperature DT51 of the water container temperature detection unit 51 becomes equal to or higher than the threshold temperature DT51a in the preheating process. You can. This makes it possible to reduce excess power. Moreover, the temperature rise of peripheral components is reduced, and component deterioration can be suppressed. Note that the threshold temperature DT51a is, for example, 70°C.

Further, in the above description, the threshold temperature of the temperature detected by the inlet side temperature detection section 42 is changed depending on the temperature of the water in the water container 5, but the present invention is not limited to this. For example, the threshold temperature of the temperature detected by the outlet side temperature detection section 41 may be changed depending on the temperature of the water in the water container 5. For example, when the temperature detected by the outlet side temperature detection unit 41 reaches a threshold temperature T41a (fourth threshold temperature) of 100°C or higher in the preheating process, the control unit 22 generates superheated steam so as not to exceed the threshold temperature T41a. The heating by the device 13 may be reduced. Furthermore, the control unit 22 may increase the threshold temperature DT41a (for example, to a threshold temperature DT41b) when the detected temperature DT51 of the water container temperature detection unit 51 exceeds the threshold temperature DT51a in the preheating process. This makes it possible to reduce excess power.

Note that when the superheated steam generator 13 is configured to perform induction heating using the induction heating coil 34, it is possible to provide an IGBT (insulated gate bipolar transistor) in the control section 22 that controls the superheated steam generator 13. IGBTs are generally mounted as chip components on the mounting surface of a board. In order to raise the temperature of the superheated steam supplied into the pot 2, it is required to increase the heating power of the superheated steam generator 13. In order to increase the heating power of the superheated steam generator 13, it is necessary to increase the amount of electricity supplied to the induction heating coil 34, which increases the amount of heat generated by the IGBT and increases the junction temperature. At this time, the collector portion of the IGBT is connected to the circuit on the board by solder, and when the junction temperature rises, the temperature of the solder also rises. At that time, the temperature may rise beyond the heat resistance temperature of the solder (that is, the temperature at which it deteriorates due to thermal shock due to long-term use). Therefore, a configuration is required that reduces the junction temperature of the IGBT and makes it difficult for heat to be transferred to the solder portion. As the configuration, for example, the configuration shown in FIG. 9 can be considered. That is, as shown in FIG. 9, the IGBT 61 is connected to the substrate 62 via the three lead wires 63 so that the IGBT 61 is located apart from the substrate 62. This IGBT 61 is mounted on a heat sink 64. According to this configuration, the heat generated by the IGBT 61 can be released to the outside through the heat sink 64. Further, it is possible to suppress heat generated from the IGBT 61 from being transmitted to the substrate 62 side.

Note that by appropriately combining any of the various embodiments described above, the effects of each embodiment can be achieved.

Although the invention has been fully described with reference to preferred embodiments and with reference to the accompanying drawings, various variations and modifications will become apparent to those skilled in the art. It is to be understood that such variations and modifications are included insofar as they do not depart from the scope of the invention according to the appended claims.

Since the rice cooker according to the present invention can increase the temperature of superheated steam supplied into the pot, it is useful as a rice cooker for home and commercial use, for example.

1 Rice cooker body 1a Pot storage part 1b Upper frame 1ba Cylindrical part 1bb Flange part 1bc Water container storage part 1c Coil base 2 Pot 3 Lid 3A Hinge shaft 3a Upper outer shell member 3aa Recessed part 3b Lower outer shell member 3c Through hole 4 Inner cover 4a Steam discharge hole 4b Superheated steam discharge hole 5 Water container 6 Water container heating device 7 Pot heating device 7a Bottom heating coil 7b Bottom outside heating coil 8 Ferrite 9 Pot temperature detection section DT9 Detection temperature 10 Steam cylinder 10a Steam escape hole 11, 12 , 14, 15 Packing 13 Superheated steam generator 16 Passage 17 Check valve 17a Ball 17b Valve seat 21 Display section 22 Control section 31 Pipe 31a Caulking section 32 Heat exchanger 32a Core rod 32b Spiral body 33 Coil bobbin 34 Induction heating coil 35 Intake pipe 36 Intake pipe suppressing member 37 Superheated steam discharge fitting 38 Pipe suppressing member 39 Packing 41 Outlet side temperature detection section T41a Threshold temperature (fourth threshold temperature)
T41b Threshold temperature T41c Threshold temperature (fifth threshold temperature)
42 Inlet side temperature detection section T42 Threshold temperature T42a Threshold temperature (first threshold temperature)
T42b Threshold temperature (second threshold temperature)
T42c Threshold temperature 51 Water container temperature detection section DT51 Detection temperature DT51a Threshold temperature (third threshold temperature)
61 IGBT
62 Board 63 Lead wire 64 Heat sink

Claims (8)

A pot and
a water container containing water;
a water container heating device that heats the water container;
A superheated steam generator that heats the steam generated from the water container to generate superheated steam exceeding 100°C and supplies the superheated steam into the pot;
an inlet-side temperature detection section that is disposed on the inlet side of the superheated steam generator that takes in the steam generated from the water container, and that detects the temperature of the steam;
an exit-side temperature detection section that is arranged on the exit side of the superheated steam generator that supplies the superheated steam into the pot and detects the temperature of the superheated steam;
a control unit that controls operations of the water container heating device and the superheated steam generator;
Equipped with
The control unit performs a preheating step in which the superheated steam generator performs heating but does not supply the superheated steam into the pot, and takes in steam generated from the water container and supplies the superheated steam into the pot. The superheated steam generator is controlled to perform the supply step, and when the temperature detected by the inlet side temperature detection section reaches a first threshold temperature of 100° C. or higher in the preheating step, the first threshold temperature is The heating by the superheated steam generator is weakened so as not to exceed the temperature, and when the temperature detected by the inlet side temperature detection section reaches a second threshold temperature higher than the first threshold temperature in the supply step, the second threshold temperature controlling the heating by the superheated steam generator so as not to exceed
rice cooker. The rice cooker according to claim 1, wherein the control unit sets the first threshold temperature to a specific temperature within a range of 100°C or more and 120°C or less. The rice cooker according to claim 1 or 2, wherein the control unit sets the second threshold temperature to a specific temperature within a range of 120°C or more and 150°C or less. further comprising a water container temperature detection section that detects the temperature of the water container,
According to any one of claims 1 to 3, the control unit increases the first threshold temperature when the temperature detected by the water container temperature detection unit becomes a third threshold temperature or higher in the preheating step. rice cooker. The control unit sets the first threshold temperature to a specific temperature within a range of 100° C. or more and less than 110° C. when the temperature detected by the water container temperature sensing portion is less than the third threshold temperature in the preheating step. , when the temperature detected by the water container temperature detection unit becomes equal to or higher than the third threshold temperature in the preheating step, the first threshold temperature is set to a specific temperature within a range of 110° C. or more and 120° C. or less. The rice cooker according to item 4. When the temperature detected by the outlet side temperature detection unit reaches a fourth threshold temperature of 100° C. or higher in the preheating step, the control unit controls heating by the superheated steam generator so as not to exceed the fourth threshold temperature. The rice cooker according to claim 4 or 5, wherein the fourth threshold temperature is increased when the temperature detected by the water container temperature detection section exceeds the third threshold temperature in the preheating step. When a predetermined period of time has elapsed in the supply step, the control unit weakens the heating by the superheated steam generator so that the temperature detected by the outlet side temperature detection unit becomes equal to or lower than a fifth threshold temperature, and then The rice cooker according to any one of claims 1 to 6, wherein heating by the water container heating device is stopped after a predetermined period has elapsed. The control unit weakens the heating by the superheated steam generator in the supply step, and stops the heating by the water container heating device after the temperature detected by the outlet side temperature detection unit falls to a fifth threshold temperature or less. The rice cooker according to any one of claims 1 to 6.

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