【０００１】
【発明の属する技術分野】
本発明は、一般家庭用あるいは業務用に使用するジャー炊飯器に関するものである。
【０００２】
【従来の技術】
従来のこの種のジャー炊飯器は、ご飯を美味しく炊くため、炊飯開始後数十分間は米に水を十分吸水させる予熱工程を設けている。また、米は高温ほど吸水しやすく、前記予熱工程においては高温制御を行っている。但し、米は約６０℃を超えると糊化（べちゃついた状態）し始める傾向があるため、約６０℃前後での温度制御としている。例えば従来の一例として特開２００２−４５２９４号公報がある。
【０００３】
【特許文献１】「特開２００２−０４５２９４号公報」。
【０００４】
【発明が解決しようとする課題】
従来よりジャー炊飯器においては、ご飯を美味しく炊くためには、十分な水と十分な加熱が必要であり、最初は弱火で米に十分吸水させて（以下この工程を予熱工程と称す）から一気に強火で加熱し（以下この工程を加熱工程と称す）沸騰させて沸騰状態をある一定時間保持し（以下この工程を沸騰維持工程と称す）米粒をα化させ（米粒がご飯として食べられる状態になることで一般的には２０分間約９８℃の温度を維持するのが理想）、内釜の底面中央に当接し内釜内の負荷（水や米）の温度を検知している感温部の温度が所定の温度でドライアップ（内釜内部の水が無くなったと判断した状態）の後、余分な水分を除去する（以下この工程をむらし工程と称す）工程を経るのが一般的である。
【０００５】
従来、内釜底面部からの加熱が主体となるジャー炊飯器において多量の米を炊いた場合、米と炊飯に必要な所定量の水を内釜に入れてから炊飯開始後、予熱工程では米の温度が約６０℃に近い温度で長時間維持するように制御しようとするが、内釜底面部からの加熱が主体となるため、米粒が上層部への熱伝導の妨げとなり、上層部と下層部との温度上昇差が生じ、上層部は下層部に比べて高温になりにくく、上層部は吸水が不十分となり炊き上がりが悪くなる傾向があった。
【０００６】
【課題を解決するための手段】
上記課題を解決するために本発明は、底面部に米粒よりも小さい穴を複数有し内釜よりも嵩が小さく上端部にフランジを有し、底面部を形状記憶合金により形成したヒンジにより側面部に取り付け、形状記憶合金の温度が所定温度（Ｔｙ）以上になると形状記憶合金が作用し底面部が開くように構成した米容器を設け、この米容器のフランジ部を内釜の鍔部に載せ内釜内に配置させるようにしたものである。
【０００７】
この米容器を内釜に載置した状態で、米容器の上方から研いだ米と炊飯に必要な所定量の水を入れると、米は米容器内に残り水だけが内釜底部に溜まり、米と水が分離した状態となる。前記状態にて炊飯を開始し予熱工程が始まると内釜底面部が誘導加熱され内釜底部に溜まった水を加熱し始める。
【０００８】
ここで、予熱工程では内釜底面温度を検知する感温部の温度が６０℃以下である所定温度Ｔｘに到達するまでは内釜底面部が最大電力で加熱される。但し、感温部の温度がＴｘに到達するまでの過程で感温部の温度が温度差Ｔｄ以上の温度降下があった場合（例えば米の落下があった時など）は、電力を下げ（以下この電力を弱電力と称す）、感温部の温度がＴｘに到達するまでは弱電力の連続加熱となる。感温部の温度がＴｘに到達すると弱電力によるＯＮ／ＯＦＦ制御に切り替わることより感温部の温度がＴｘで維持される構成である。
【０００９】
通常、予熱工程が始まると内釜底部に溜まった水が最大電力で加熱され、米粒が無い分、水の温度は上下層の温度差が少なく且つ早く温度上昇し、水温がＴｘになると水温をＴｘで維持する。また、水の温度上昇に追従して内釜内部の雰囲気温度が上昇し内釜内に配置した米容器の形状記憶合金（ヒンジ）部の温度も上昇するが、形状記憶合金の温度は炊飯開始時の条件（炊飯量、室温、米の温度等）によって温度上昇の勾配が異なる。ここで、形状記憶合金の所定温度Ｔｙは、炊飯開始時の条件で最も温度上昇の勾配が緩やかな条件で且つ予熱工程時間の２／３を経過した時点での温度をＴｙと定める。Ｔｙを前記温度と定めることで、米容器の底面は予熱工程時間の２／３以内で確実に開き、米容器上に溜まった米が内釜底に落ちて加熱された高温の水と混ざるものである。
【００１０】
米と水が混ざると、水の熱が米に奪われ負荷（米＋水）全体の温度が温度差Ｔｄ以上の温度降下を生じる。混ざり合った時点での水温がＴｘになるまでの途中過程の場合は、電力は最大電力から弱電力制御に切り替わり、負荷の温度がＴｘに到達するまでは弱電力の連続加熱となり、負荷の温度がＴｘに到達すると弱電力のＯＮ／ＯＦＦ制御により負荷温度がＴｘで維持される。また、混ざり合った時点での水温がＴｘで維持されている場合は、弱電力のＯＮ／ＯＦＦ制御により負荷温度がＴｘで維持されるものである。
【００１１】
米は高温の水と混ざることで、米の全体層が均一に且つ早く温度上昇する。また、米は炊飯開始時の条件によっても異なるが最短でも予熱工程時間の１／３は高温で維持され、予熱工程を終了する。
【００１２】
本発明はこのような構成としたことにより、上層部の米は吸水が十分となり炊き上がりも良好となるものである。
【００１３】
【発明の実施の形態】
本発明は、本体と、本体の内壁を構成し内容器と側面リングとで構成する樹脂製の保護枠と、本体及び保護枠に着脱自在に収納され上端部に鍔部を有した内釜と、保護枠の外側底面部に配置し内釜の底面部を誘導加熱する底部加熱コイルと、内釜底面中央に当接し内釜の温度を検知する感温部とで構成するジャー炊飯器において、底面部に複数の小穴を有し、内釜よりも嵩が小さく、上端部にフランジを有して内釜の鍔部に着脱自在に載置し、米を収納し、かつ炊飯開始から数分間米と水を分離した状態に保持する米容器を設けたジャー炊飯器としたものである。
【００１４】
また、米容器は上端にフランジを有し、底面部は形状記憶合金よりなるヒンジを介して側面部に取り付けられ、炊飯時所定温度以上になるとヒンジが変形することにより底面部が開放するように構成したものである。
【００１５】
【実施例】
以下本発明の一実施例を図面に基づいて詳細に説明する。図１は本発明の一実施例を示すジャー炊飯器の断面図である。図２は同じく米容器の斜視図である。図３は同じく米容器の斜視図であり、底面部が開放した状態図である。図４は同じく要部断面図である。
【００１６】
図において、１は本体であり、２は内釜である。内釜２の上端全周に鍔部２ａを有している。３は蓋部であり、内釜２の上部開口を覆い開閉自在に取り付けられている。
【００１７】
蓋部３は本体１の上方を覆う蓋本体３ａと、蓋本体３ａ中央部に空洞状で着脱自在に取り付けられた蒸気口４と、蓋本体３ａ下部にシリコンゴムヒーター式の蓋ヒーター５とサーミスタ式の蓋センサー６が貼り付けられた円盤状で中央部に穴を設けたアルミ製の内放熱板７と、内放熱板７下方に円盤状で中央に複数の穴を設けたアルミ製の外放熱板８と、外放熱板８の縁全周に設置され蓋部３と内釜２とをシールするゴム製の蓋パッキン９から構成されている。この蓋部３と本体１から主に外観が構成されているものである。
【００１８】
内釜２の外周部には保護枠１２の下部を構成する樹脂製の内容器１０と、保護枠１２の側面部を構成する樹脂製で上下開口筒状の側面リング１１とを備え、また内容器１０下方には渦状に形成され内釜２の底面部を誘導加熱する底部加熱コイル１３を有し、内容器１０中央部には内釜２内の負荷（水や米）の温度を検知する感温部１４が設置され（以下説明では、感温部１４の温度と内釜２内の負荷の温度は殆ど同じとする）、更に本体１前部には制御部１５が配置されている。
【００１９】
内釜２の内部には図２のような、底面部１６ｃに複数の小穴及び側面に複数で同形状の凸部１６ｄを有し、底面部１６ｃが扉状に開閉するステンレス製の米容器１６が設置されている。
【００２０】
米容器１６は内釜２よりも深さが浅く、外径も小さく、容積が小さく形成されている。米容器１６のフランジ１６ａ部の外径は内釜２の鍔部２ａの外径よりも小さく、底面部１６ｃの複数の穴径は１ｍｍ以下で米が通過しない大きさとなっている。また、米容器１６の底面開閉部に記憶形状が板状の形状記憶合金により形成されたヒンジ１６ｂが溶接設置され、形状記憶合金の温度が所定温度Ｔｙ以上になるとヒンジ１６ｂが板状に戻り、図３のように米容器１６の底面部１６ｃが下方に開く構成となっている。
【００２１】
以下、上記構成からなる本実施例の作用について説明する。
【００２２】
まず、形状記憶合金よりなるヒンジ１６ｂを直角に曲げ図２のように底面部１６ｃが閉じた状態の米容器１６とし、蓋部３を開け、米容器１６のフランジ１６ａを内釜２の鍔部２ａに乗せるように内釜２の内部に米容器１６を配置する。この時、米容器１６の凸部１６ｄと内釜２との隙間ｄは図４に示す鍔部２ａとフランジ１６ａ部との掛り代Ｄよりも小さい関係となっているため、米容器１６のフランジ１６ａが内釜２の鍔部２ａから脱落することなく米容器１６は内釜２のほぼ中心位置に配置されるようになっている。
【００２３】
米容器１６を内釜２内に配置後、米容器１６の上方から研いだ米と炊飯に必要な所定量の水を内釜２内に入れると、米は米容器１６内に残り水だけが内釜２底部に溜まり、米と水が分離した状態となる。
【００２４】
上記状態にて炊飯を開始し予熱工程が始まると、制御部１５により底部加熱コイル１３に通電され底部加熱コイル１３と対向する内釜２が発熱し、内釜２の底部に溜まった水を加熱し始める。
【００２５】
ここで、予熱工程の底面加熱制御について説明する。予熱工程開始後、内釜２内の負荷（水）温度が６０℃になるまでは底面加熱は最大電力で加熱する。但し、予熱工程開始から６０℃になるまでの過程で何らかの事情により温度差Ｔｄ以上の温度降下があった場合は電力を下げ（以下この電力を弱電力と称す）、負荷の温度が６０℃に達するまで弱電力の連続加熱となる。負荷の温度が６０℃に達すると感温部１４の温度が６０℃を境に弱電力のＯＮ／ＯＦＦ制御に切り替わり、負荷の温度が６０℃で維持される。
【００２６】
また、弱電力は予熱工程開始から２分経過までの水温の温度勾配によって、制御部１５により電力が数段階で選択される（以下前記電力の選択を容量判定と称す）。予熱工程が始まると、内釜２底部に溜まった水が最大電力で加熱され、米粒が無い分、水の温度は上下層の温度差が少なく且つ早く温度上昇する。予熱工程開始から２分経過後炊飯容量判定によって電力の大きさが選択される。また、水の温度上昇に追従して内釜２内の雰囲気温度が上昇し内釜２内に配置した米容器１６のヒンジ（形状記憶合金）１６ｂ部の温度も上昇する。
【００２７】
ここで、形状記憶合金１６ｂの所定温度Ｔｙは炊飯開始時の条件（炊飯量、室温、米の温度等）で最も温度上昇の勾配が緩やかな条件で且つ予熱工程時間の２／３を経過した時点での温度をＴｙと定めるものである。
【００２８】
上記仕様にて最大炊飯量を炊いた場合、負荷が多いため、予熱工程開始からの水の温度上昇は遅くなるので、電力は容量判定で最高位の電力が選択される。また、形状記憶合金１６ｂの温度は水温の温度上昇が遅く且つ多量の米と触れているので温度上昇が遅い。但し、上記仕様から遅くても予熱工程時間の２／３経過までには形状記憶合金１６ｂの温度はＴｙに達しているので、予熱工程時間の２／３経過までには形状記憶合金１６ｂが記憶形状（板状）に戻り、米容器１６の底面部１６ｃが開いて（図３の状態）米容器１６内に溜まっていた米は内釜２底に落ちて、高温に加熱された水と混ざり合う。
【００２９】
米と水が混ざり合うと水の熱が米に奪われ負荷（米＋水）全体の温度が温度差Ｔｄ以上の温度降下を生じる。この時、混ざり合った時点での水温が６０℃になるまでの途中過程の場合は、加熱は最大電力加熱から弱電力加熱に切り替わり、負荷（米＋水）の温度が６０℃に達するまでは弱電力の連続加熱となり、６０℃に達すると弱電力のＯＮ／ＯＦＦ制御により負荷の温度は６０℃に維持される。また、混ざり合った時点での水温が６０℃で維持されている場合は、負荷（米＋水）の温度を６０℃に維持するよう弱電力でＯＮ／ＯＦＦ制御される。
【００３０】
米は少なくとも予熱時間の１／３以上は高温の水に浸り、米全体が均一で且つ早く温度上昇するので、全体的に吸水が早く進み、吸水が上下層とも十分に行き渡り予熱工程が終了する。
【００３１】
【発明の効果】
以上、本発明はこのような構成としたことにより、米全体が均一で美味しく炊き上がるものである。また、米と水が混ざり合う時の水温（本実施例では最高水温６０℃）を高めに設定することによって、米と水が混ざった後米の温度は急上昇するので約６０℃の高温で維持する時間が長くなり、より吸水が十分となり炊き上がりが更に良くなる。
【図面の簡単な説明】
【図１】本発明の一実施例を示すジャー炊飯器の断面図である。
【図２】同じく要部斜視図である。
【図３】同じく要部斜視図である。
【図４】同じく要部拡大断面図である。
【符号の説明】
１：本体、２：内釜、２ａ：鍔部、３：蓋部、１０：内容器、１１：側面リング、１２：保護枠、１３：底部加熱コイル、１４：感温部、１５：制御部、１６：米容器、１６ａ：フランジ、１６ｂ：ヒンジ（形状記憶合金）、１６ｃ：底面部。[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a jar rice cooker for general household use or business use.
[0002]
[Prior art]
This kind of conventional jar rice cooker is provided with a preheating step of making the rice sufficiently absorb water for several tens of minutes after the start of rice cooking in order to cook rice deliciously. Rice is more likely to absorb water at higher temperatures, and high temperature control is performed in the preheating step. However, since the rice tends to gelatinize (sticky) when the temperature exceeds about 60 ° C., the temperature is controlled at about 60 ° C. For example, there is JP-A-2002-45294 as an example of the related art.
[0003]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-045294.
[0004]
[Problems to be solved by the invention]
Conventionally, in a jar rice cooker, to cook rice deliciously, it is necessary to have sufficient water and sufficient heating. At first, the rice is allowed to absorb water sufficiently over a low heat (hereinafter this process is referred to as a preheating process). It is heated over high heat (hereinafter, this process is called a heating process) and boiled to maintain the boiling state for a certain period of time (hereinafter, this process is called a boiling maintenance process). The rice grains are pre-gelatinized (the rice grains can be eaten as rice) In general, it is ideal to maintain a temperature of about 98 ° C for 20 minutes.) A temperature sensing part that abuts the center of the bottom of the inner pot and detects the temperature of the load (water or rice) in the inner pot. After drying at a predetermined temperature at a predetermined temperature (a state in which water in the inner pot has been depleted), a step of removing excess water (hereinafter, this step is referred to as a spotting step) is generally performed. is there.
[0005]
Conventionally, when a large amount of rice is cooked in a jar rice cooker that mainly heats from the bottom of the inner pot, the rice and a predetermined amount of water required for rice cooking are put into the inner pot, and then rice cooking is started. Is controlled to be maintained at a temperature close to about 60 ° C. for a long time. However, since heating mainly from the bottom portion of the inner pot, rice grains hinder heat conduction to the upper layer portion, and the upper layer portion is not heated. There was a difference in temperature rise from the lower layer, and the upper layer was less likely to be heated to a higher temperature than the lower layer, and the upper layer tended to absorb insufficient water, resulting in poor cooking.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention has a plurality of holes smaller than rice grains on a bottom surface, a smaller volume than an inner pot, a flange on an upper end portion, and a bottom surface portion formed by a hinge formed of a shape memory alloy. A rice container configured such that when the temperature of the shape memory alloy reaches a predetermined temperature (Ty) or more, the bottom surface of the rice container is opened by the action of the shape memory alloy, and the flange of the rice container is attached to the flange of the inner pot. It is designed to be placed inside the loading pot.
[0007]
When the rice container is placed in the inner pot and the rice honed from the top of the rice container and a predetermined amount of water required for cooking are added, the rice remains in the rice container and only water is collected at the bottom of the inner pot. Rice and water are separated. In this state, rice cooking is started, and when the preheating step is started, the bottom portion of the inner pot is induction-heated to start heating water accumulated at the bottom of the inner pot.
[0008]
Here, in the preheating step, the bottom portion of the inner pot is heated with the maximum electric power until the temperature of the temperature sensing portion for detecting the bottom temperature of the inner pot reaches a predetermined temperature Tx of 60 ° C. or less. However, in the case where the temperature of the temperature sensing portion has decreased by the temperature difference Td or more in the process until the temperature of the temperature sensing portion reaches Tx (for example, when rice has fallen), the power is reduced ( Hereinafter, this power is referred to as weak power), and the weak power is continuously heated until the temperature of the temperature sensing portion reaches Tx. When the temperature of the temperature sensing section reaches Tx, the temperature is switched to ON / OFF control using weak power, so that the temperature of the temperature sensing section is maintained at Tx.
[0009]
Normally, when the preheating process starts, the water accumulated at the bottom of the inner pot is heated with the maximum power, and the temperature of the water rises quickly and quickly due to the absence of rice grains when the temperature difference between the upper and lower layers is small and the water temperature becomes Tx. Maintain at Tx. Also, the temperature of the atmosphere inside the inner pot rises following the rise in the temperature of the water, and the temperature of the shape memory alloy (hinge) portion of the rice container placed in the inner pot also rises, but the temperature of the shape memory alloy starts to cook rice. The gradient of the temperature rise varies depending on the conditions at the time (rice cooked, room temperature, rice temperature, etc.). Here, as the predetermined temperature Ty of the shape memory alloy, the temperature at the time when the gradient of the temperature rise is the gentlest in the condition at the start of rice cooking and at the time when 2/3 of the preheating step time has elapsed is defined as Ty. By defining Ty as the above temperature, the bottom surface of the rice container is surely opened within two-thirds of the preheating process time, and the rice accumulated on the rice container falls to the bottom of the inner pot and mixes with heated high-temperature water. It is.
[0010]
When the rice and the water are mixed, the heat of the water is taken away by the rice, and the temperature of the entire load (rice + water) drops by a temperature difference Td or more. In the middle of the process until the water temperature at the time of mixing becomes Tx, the power is switched from the maximum power to the weak power control, and until the temperature of the load reaches Tx, continuous heating of the weak power is performed. Reaches Tx, the load temperature is maintained at Tx by ON / OFF control of the weak power. When the water temperature at the time of mixing is maintained at Tx, the load temperature is maintained at Tx by ON / OFF control of weak electric power.
[0011]
When rice is mixed with high-temperature water, the temperature of the whole rice layer rises uniformly and quickly. Although rice varies depending on the conditions at the start of rice cooking, at least one third of the preheating step time is maintained at a high temperature, and the preheating step ends.
[0012]
According to the present invention, the rice in the upper layer has sufficient water absorption and the cooked rice becomes good by adopting such a constitution.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention relates to a main body, a protective frame made of a resin that forms an inner wall of the main body and includes an inner container and a side ring, an inner pot that is detachably housed in the main body and the protective frame, and has a flange at an upper end portion. In a jar rice cooker comprising a bottom heating coil arranged on the outer bottom surface of the protection frame and inductively heating the bottom of the inner pot, and a temperature sensing part which abuts on the bottom center of the inner pot and detects the temperature of the inner pot, It has a plurality of small holes on the bottom part, is smaller in volume than the inner pot, has a flange on the upper end, is detachably mounted on the flange part of the inner pot, stores rice, and for a few minutes from the start of rice cooking This is a jar rice cooker provided with a rice container for holding rice and water in a separated state.
[0014]
In addition, the rice container has a flange at the upper end, the bottom portion is attached to the side portion via a hinge made of a shape memory alloy, so that when the temperature becomes a predetermined temperature or more during rice cooking, the hinge is deformed so that the bottom portion is opened. It is composed.
[0015]
【Example】
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of a jar rice cooker showing one embodiment of the present invention. FIG. 2 is a perspective view of the rice container. FIG. 3 is a perspective view of the rice container, showing a state where the bottom portion is open. FIG. 4 is a cross-sectional view of the main part.
[0016]
In the figure, 1 is a main body, and 2 is an inner pot. The inner pot 2 has a flange 2a all around the upper end. Reference numeral 3 denotes a lid, which covers the upper opening of the inner pot 2 and is attached so as to be freely opened and closed.
[0017]
The lid 3 includes a lid main body 3a that covers the upper part of the main body 1, a hollow steam port 4 that is detachably attached to the center of the lid main body 3a, a silicon rubber heater-type lid heater 5 and a thermistor below the lid main body 3a. Aluminum heat radiating plate 7 having a disc-shaped center hole with a lid sensor 6 attached thereto, and an aluminum outer heat radiating plate having a plurality of disc-shaped holes below the inner heat radiating plate 7 The heat radiating plate 8 includes a rubber lid packing 9 installed around the entire periphery of the outer heat radiating plate 8 and sealing the lid 3 and the inner pot 2. The outer appearance is mainly composed of the lid 3 and the main body 1.
[0018]
An outer peripheral portion of the inner pot 2 is provided with a resin inner container 10 constituting a lower portion of the protection frame 12 and a resin-made upper and lower opening cylindrical side ring 11 constituting a side portion of the protection frame 12. A bottom heating coil 13 which is formed in a spiral shape and inductively heats a bottom portion of the inner pot 2 is provided below the inner vessel 10, and a temperature of a load (water or rice) in the inner pot 2 is detected in a central portion of the inner vessel 10. A temperature sensing unit 14 is provided (in the following description, the temperature of the temperature sensing unit 14 and the temperature of the load in the inner pot 2 are almost the same), and a control unit 15 is disposed at the front of the main body 1.
[0019]
As shown in FIG. 2, a stainless steel rice container 16 having a plurality of small holes in a bottom portion 16c and a plurality of convex portions 16d of the same shape in a side surface, and the bottom portion 16c opens and closes like a door, as shown in FIG. Is installed.
[0020]
The rice container 16 is formed to be smaller in depth, smaller in outer diameter and smaller in volume than the inner pot 2. The outer diameter of the flange 16a portion of the rice container 16 is smaller than the outer diameter of the flange portion 2a of the inner pot 2, and the plurality of hole diameters of the bottom portion 16c are 1 mm or less, and are large enough to prevent rice from passing therethrough. In addition, a hinge 16b whose memory shape is formed of a plate-shaped shape memory alloy is welded to the bottom opening and closing portion of the rice container 16, and when the temperature of the shape memory alloy becomes equal to or higher than a predetermined temperature Ty, the hinge 16b returns to the plate shape, As shown in FIG. 3, the bottom portion 16c of the rice container 16 is configured to open downward.
[0021]
Hereinafter, the operation of the present embodiment having the above configuration will be described.
[0022]
First, the hinge 16b made of a shape memory alloy is bent at a right angle to make the rice container 16 in a state where the bottom portion 16c is closed as shown in FIG. 2, the lid 3 is opened, and the flange 16a of the rice container 16 is attached to the flange portion of the inner pot 2. A rice container 16 is arranged inside the inner pot 2 so as to be put on the rice cooker 2a. At this time, the gap d between the convex portion 16d of the rice container 16 and the inner pot 2 has a relationship smaller than the hook allowance D between the flange portion 2a and the flange 16a shown in FIG. The rice container 16 is arranged at a substantially central position of the inner pot 2 without the 16a falling off from the flange portion 2a of the inner pot 2.
[0023]
After the rice container 16 is placed in the inner pot 2, the rice ground from above the rice container 16 and a predetermined amount of water necessary for cooking rice are put into the inner pot 2, and the rice remains in the rice container 16 and only water remains. The rice and water accumulate at the bottom of the inner pot 2 so that rice and water are separated.
[0024]
When rice cooking is started in the above state and the preheating step is started, the control unit 15 supplies electricity to the bottom heating coil 13 so that the inner pot 2 facing the bottom heating coil 13 generates heat and heats water accumulated at the bottom of the inner pot 2. Begin to.
[0025]
Here, the bottom surface heating control in the preheating step will be described. After the start of the preheating step, the bottom heating is performed with the maximum electric power until the load (water) temperature in the inner pot 2 reaches 60 ° C. However, if there is a temperature drop of not less than the temperature difference Td for some reason in the process from the start of the preheating process to 60 ° C., the power is reduced (hereinafter, this power is referred to as weak power), and the temperature of the load is reduced to 60 ° C. Continuous heating with weak electric power until reaching. When the temperature of the load reaches 60 ° C., the temperature of the temperature sensing unit 14 is switched to ON / OFF control of the weak power after the temperature of 60 ° C., and the temperature of the load is maintained at 60 ° C.
[0026]
Further, the weak power is selected in several stages by the control unit 15 by the temperature gradient of the water temperature from the start of the preheating step to the lapse of 2 minutes (hereinafter, the selection of the power is referred to as capacity determination). When the preheating step is started, the water collected at the bottom of the inner pot 2 is heated with the maximum electric power, and the temperature of the water rises quickly because of the absence of rice grains, with a small difference in temperature between the upper and lower layers. Two minutes after the start of the preheating step, the power level is selected by the rice cooking capacity determination. Further, the temperature of the atmosphere in the inner pot 2 rises following the rise in the temperature of the water, and the temperature of the hinge (shape memory alloy) 16b of the rice container 16 disposed in the inner pot 2 also rises.
[0027]
Here, the predetermined temperature Ty of the shape memory alloy 16b is a condition in which the temperature rise is the gentlest under the conditions at the time of starting rice cooking (cooking amount, room temperature, rice temperature, etc.), and has passed 2/3 of the preheating step time. The temperature at the time is defined as Ty.
[0028]
When the maximum amount of cooked rice is cooked according to the above specification, the load is large, and the temperature rise of the water from the start of the preheating step is delayed, so that the highest power is selected as the power in the capacity determination. In addition, the temperature of the shape memory alloy 16b rises slowly because the temperature of the water temperature rises slowly, and the temperature rises slowly because it touches a large amount of rice. However, since the temperature of the shape memory alloy 16b has reached Ty by 2/3 of the preheating process time at the latest from the above specification, the shape memory alloy 16b is stored by 2/3 of the preheating process time. Returning to the shape (plate shape), the bottom portion 16c of the rice container 16 is opened (the state of FIG. 3), and the rice accumulated in the rice container 16 falls to the bottom of the inner pot 2 and mixes with the water heated to a high temperature. Fit.
[0029]
When the rice and the water are mixed, the heat of the water is taken away by the rice and the temperature of the entire load (rice + water) drops by a temperature difference Td or more. At this time, in the case of the process in which the water temperature at the time of mixing becomes 60 ° C, the heating is switched from the maximum power heating to the weak power heating, and until the load (rice + water) temperature reaches 60 ° C. The heating is continued with weak electric power. When the heating reaches 60 ° C., the load temperature is maintained at 60 ° C. by ON / OFF control of the weak electric power. When the water temperature at the time of mixing is maintained at 60 ° C., ON / OFF control is performed with weak power to maintain the temperature of the load (rice + water) at 60 ° C.
[0030]
Rice is immersed in high-temperature water for at least 1/3 or more of the preheating time, and the temperature of the whole rice is increased uniformly and quickly, so that water absorption proceeds quickly, and water absorption is sufficiently distributed to upper and lower layers, and the preheating process is completed. .
[0031]
【The invention's effect】
As described above, according to the present invention, rice is cooked uniformly and deliciously by adopting such a configuration. Also, by setting the water temperature when the rice and the water are mixed (the maximum water temperature of 60 ° C. in this embodiment) to be higher, the temperature of the rice rises rapidly after the rice and the water are mixed, so that the rice is maintained at a high temperature of about 60 ° C. The time to do it becomes longer, the water absorption becomes more sufficient, and the cooking becomes even better.
[Brief description of the drawings]
FIG. 1 is a sectional view of a jar rice cooker showing one embodiment of the present invention.
FIG. 2 is a perspective view of an essential part of the same.
FIG. 3 is a perspective view of an essential part of the same.
FIG. 4 is an enlarged sectional view of a main part of the same.
[Explanation of symbols]
1: body, 2: inner pot, 2a: flange, 3: lid, 10: inner container, 11: side ring, 12: protective frame, 13: bottom heating coil, 14: temperature sensing unit, 15: control unit , 16: rice container, 16a: flange, 16b: hinge (shape memory alloy), 16c: bottom surface.
