JP3997895B2

JP3997895B2 - Induction heating device

Info

Publication number: JP3997895B2
Application number: JP2002336447A
Authority: JP
Inventors: 英明小林; 章片岡; 勝行相原; 敏弘慶島
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2002-11-20
Filing date: 2002-11-20
Publication date: 2007-10-24
Anticipated expiration: 2022-11-20
Also published as: JP2004171926A

Description

【０００１】
【発明の属する技術分野】
本発明は、主に一般家庭での加熱調理や業務用で金属加熱等を行う誘導加熱装置に関する。
【０００２】
【従来の技術】
従来の誘導加熱装置は、加熱コイル下面を主に冷却するか、または側面から加熱コイルの下面を主に冷却している（例えば、特許文献１参照）。
【０００３】
【特許文献１】
特願２００１−２６０７５３号公報（第３〜５図）
【０００４】
【発明が解決しようとする課題】
銅やアルミニウム等の鍋を加熱するために鉄鍋に適した約２０ら約３０ｋＨｚよりも高いやく４０から約１００ｋＨｚの高周波電流を加熱コイルに流さなければならなかった。また、高出力な誘導加熱装置が要望されている。周波数が高くなれば表皮効果で実効抵抗が高くなり発熱が大きくなる。また、電流値を大きくすると加熱コイルの自己発熱も大きくなる。以上のように誘導加熱装置の性能を高めるためには、加熱コイルの冷却を効率的に行うことが要求されている。
【０００５】
本発明は、加熱コイルの中央から外周方向に加熱コイルの上面と下面との両方を同時に冷却できる誘導加熱装置を提供することを目的とする。
【０００６】
【課題を解決するための手段】
この課題を解決するために本発明は、発熱の大きい加熱コイルを効率的に冷却するために、加熱コイルの中央に位置する通風穴を通して冷却風を加熱コイル上面に分岐誘導して加熱コイル上面の中央から放射状に冷却風を平面プレートと加熱コイルとの間の隙間を通過させるとともに加熱コイル下面も冷却できるように下方に向かって伸設された防風部材を有する温度検知部を通風穴に形成したものである。
【０００７】
これにより、従来よりも高周波数の電流を加熱コイルに流したり、加熱コイルへ流す電流値を大きくして、加熱コイルの発熱が多くなっても、十分に冷却できる誘導加熱装置が得られる。特に非磁性金属を加熱することが可能になる。
【０００８】
【発明の実施の形態】
本発明の請求項１に記載の発明は、被加熱物を載置する平面プレートと、前記平面プレート下方に位置し、略ドーナツ状で中央に通風穴を有する加熱コイルと、前記平面プレートと加熱コイルとの間に設けた隙間と、送風装置と、前記加熱コイル下方に位置して前記送風装置が発生する冷却風の一部を誘導して前記加熱コイルの略中央下から上方に前記冷却風を誘導する送風誘導壁とを有し、前記送風誘導壁で前記通風穴に誘導された前記冷却風を、前記加熱コイルの下面と前記隙間とに前記通風穴の中央から均等に放射状に流すように下方に向かって伸設された防風部材を有する温度検知部を前記通風穴に形成したものであり、加熱コイルの上下両面を冷却できるという作用を有する。
【０００９】
請求項２に記載の発明は、被加熱物を載置する平面プレートと、前記平面プレート下方に位置し、略ドーナツ状で中央に通風穴を有する加熱コイルと、前記平面プレートと加熱コイルとの間に設けた隙間と、送風装置と、前記加熱コイル下方に位置して前記送風装置が発生する冷却風の一部を誘導して前記加熱コイルの略中央下から上方に前記冷却風を誘導する送風誘導壁とを有し、前記送風誘導壁で前記通風穴に誘導された前記冷却風を、前記加熱コイルの下面と前記隙間とに前記通風穴の中央から均等に放射状に流すように、前記通風穴の中央から偏心して温度検知部を配置する構成としたものであり、送風を通風穴の一部から加熱コイルの上方に通過させると同時に通過した冷却風の流れる方向を制御することができ、また温度検知部で加熱コイルの下方に送風を分岐させて温度検知部の位置と面積により下法に分岐する風の量を制御するという作用を有する。
【００１０】
請求項３に記載の発明は、被加熱物を載置する平面プレートと、前記平面プレート下方に位置する加熱コイルと、前記平面プレートと加熱コイルとの間に設けた隙間と、送風装置と、前記加熱コイル下方に位置して前記送風装置が発生する冷却風の一部を誘導して前記加熱コイルの略中央下から上方に前記冷却風を誘導する送風誘導壁とを有し、前記加熱コイルは略ドーナツ状で中央に通風穴を有し、前記冷却風の一部を前記平面プレートと前記加熱コイルとの間の前記隙間を通過させる構成とした誘導加熱装置であって、前記加熱コイルは基台と、コイルと、前記コイルの中心から放射状に配置したフェライトと、コイル押さえとを備え、前記コイル押さえは前記コイル外周を覆う壁と前記壁から前記コイル上面に伸設した複数の押さえ爪とを備え、前記壁に風穴を設けた構成としたものであり、加熱コイルの上方に誘導された冷却風を放射状に放散させて加熱コイル上面から放射状に放散させて効率の良い冷却が可能になるという作用を有する。
【００１１】
請求項４に記載の発明は、被加熱物を載置する平面プレートと、前記平面プレート下方に位置する加熱コイルと、前記平面プレートと加熱コイルとの間に設けた隙間と、送風装置と、前記加熱コイル下方に位置して前記送風装置が発生する冷却風の一部を誘導して前記加熱コイルの略中央下から上方に前記冷却風を誘導する送風誘導壁とを有し、前記加熱コイルは略ドーナツ状で中央に通風穴を有し、前記冷却風の一部を前記平面プレートと前記加熱コイルとの間の前記隙間を通過させる構成とした誘導加熱装置であって、前記加熱コイルは基台と、コイルと、前記コイルの中心から放射状に配置した上に開いたコ字状フェライトと、コイル押さえとを備え、前記コイル押さえは、前記加熱コイル外周に位置し、前記コ字状フェライト配置の外周を覆う壁と、前記壁から前記コイル上面に伸設した複数の押さえ爪とを備え、前記コ字状フェライトの内周凸部が前記コイル内周より内側に位置し、外周凸部が前記コイル外周より外側に位置するように配置するとともに、前記コイル押さえの壁は風穴を有し、前記風穴は、一の前記コ字状フェライトの外周凸部と他の前記コ字状フェライトの外周凸部との間に設けた構成としたものであり、加熱コイルの上方に誘導された風を放射状に放散させて加熱コイル上面から放射状に放散させて効率の良い冷却が可能になると同時にフェライトの高さと同じ高さで風穴を形成することができて、高さがコンパクトな加熱コイルを設計することができるという作用を有する。
【００１２】
請求項５に記載の発明は、加熱コイル外周に２本のリング状導体を上下方向に分離して略平行に配置し、上下のリング状導体の間に風穴が位置する構成としたものであり、加熱コイルの上方に誘導された冷却風を放射状に放散させて加熱コイル上面から放射状に放散させて効率の良い冷却が可能になるという作用を有する。
【００１３】
請求項６に記載の発明は、前記加熱コイル上部と前記平面プレートとの間に遮蔽板を配置し、前記遮蔽板は、通風穴から前記加熱コイルのコイル上面に誘導された風の前記遮蔽板上方への進路を阻み、前記遮蔽板と前記コイル上面との間を通って前記加熱コイル外周に拡散する構成としたものであり、通風穴から加熱コイル上方に分岐した冷却風を遮蔽板で押さえ込んで加熱コイル上部で放射状に放散させて加熱コイル上面を効率的に冷却することができるという作用を有する。
【００１４】
請求項７に記載の発明は、コイル押さえは壁から中心に向かう複数の押さえ爪と、押さえ爪の先端付近に伸設した下方に凸な突起とを有し、突起がコイルに当接するとともに、押さえ爪本体はコイルから離れて位置する構成としたものであり、加熱コイルの上面を効率的に冷却できるという作用を有する。
【００１５】
請求項８に記載の発明は、加熱コイル上部と平面プレートとの間に遮蔽板を配置し、遮蔽板と平面プレートとの間に非磁性金属板を配置し、加熱コイルと遮蔽板との間か遮蔽板と非磁性金属板との間か非磁性金属板と平面プレートとの間かの少なくとも一つ以上に隙間を設けて、通風穴から前記加熱コイルのコイル上面に誘導された冷却風の前記遮蔽板上方への進路を阻み、冷却風が前記隙間を通って加熱コイル外周に拡散する構成としたものであり、加熱コイルと遮熱板と非磁性金属板と平面プレートとの間に任意に隙間を設けて通風穴からの冷却風を隙間に通すことでコイルより上に位置する任意の部品を冷却できるという作用を有する。
【００１６】
請求項９に記載の発明は、加熱コイルを駆動する制御回路をインバータ回路で形成し、インバータ回路はアルミニウムや銅等の高導電率かつ低抵抗の非磁性金属を加熱可能とした構成としたものであり、加熱コイルの発熱が大きい場合でも加熱コイルの上下両面を均一に冷却するという作用を有する。
【００１７】
【実施例】
（実施例１）
以下本発明の実施例について、図面を参照しながら説明する。
【００１８】
１１は金属板で形成された上部が開口した直方体の外郭である。１２は外郭の上部を塞ぐように固定される金属板で形成された天面枠であり、天面枠１２には長方形の耐熱ガラス板で形成された平面プレート１３が外周を天面枠１２に接着されて水密的に固定されている。平面プレート１３には鍋等を置く位置がデザインされている。１４は天面枠１２後方に横方向に配置された吸排気グリルであり、多数の通気穴１５を有して天面枠１２に着脱自在に載置されている。１６は天面枠１２を外郭１１前部に固定するフックである。
【００１９】
１７は外郭１１の左側に配置されたロースタであり、把手１８を引き出して使用する。ロースタ１７はシーズヒータ（図示せず）で加熱される構成である。１９は制御回路２０が収納された回路部である。２１は操作部であり、使用するときは前面下部を軸支されて前方に傾斜して飛びだす構造になっている。
【００２０】
２２は外郭１１の左部に配置された第１の加熱コイルであり誘導加熱により最大３ｋＷの加熱能力がある。第１の加熱コイル２２は約２０ｋＨｚの周波数の電源で駆動され、磁性金属で形成された鍋等を加熱する。２３は外郭１１の右部に配置された第２の加熱コイルである。第２の加熱コイル２３は約２ｋＷの加熱能力がある。第２の加熱コイル２３は金属の種類により約２０ｋＨｚまたは約６０ｋＨｚの周波数の電源で駆動される。第２の加熱コイル２３の上方平面プレート１３上に載置された鍋等の金属の種類が磁性金属か非磁性金属かは、第２の加熱コイル２３の負荷電流から判別して駆動電源の周波数を決定する。磁性金属の場合は２０ｋＨｚにし非磁性金属の場合は６０ｋＨｚにする。
【００２１】
前記制御回路２０は第１の加熱コイル２２に約２０ｋＨｚの周波数の電流を供給し、第２の加熱コイル２３に約２０ｋＨｚと約６０ｋＨｚの周波数の電流を供給するインバータ回路を備えている。
【００２２】
２４は３個で第１の加熱コイル２２を支持する第１の支持ばねである。２５は３個で第２の加熱コイル２３を支持する第２の支持ばねである。２６は第１の加熱コイル２２と第２の加熱コイル２３との中央奥に位置する円盤状のクイックラジエントヒータであり、ガラス鍋や土鍋等を加熱する機能がある。
【００２３】
回路部１９について説明する。第２の加熱コイル２３を制御する上基板２７と上基板２７を収納する上基板ケース２８と、第１の加熱コイル２２を制御する中基板２９と中基板２９を収納する中基板ケース３０と、第２の加熱コイル２３に供給する電源を作る下基板３１と下基板３１を収納する下基板ケース３２とを上から順に水平に積み重ねて、回路部１９に収納されている。回路部１９には外郭１１の右後方に位置する収納部３３が形成されている。
【００２４】
３４は送風装置を形成する縦軸型のシロッコファンであり、前記回路部１９の収納部３３に収納されて回路部１９に送風する。上基板２７、中基板２９、下基板３１のそれぞれにはシロッコファン３４の送風口３５に近い位置に上基板２７には上ヒートシンク３６、中基板２９上には中ヒートシンク３７、下基板３１上には下ヒートシンク３８がそれぞれ位置しており、各々の基板２７、２９、３１上では発熱の多い各ヒートシンク３６、３７、３８を最初に冷却する構成となっている。
【００２５】
３９は上基板ケース２８の上に位置する基板ケースカバーであり、基板ケースカバー３９の上部には第２の支持ばね２５が位置する。基板ケースカバー３９は天面４０を有して略長方形の箱形状を成し、上基板ケース２８とシロッコファン３４との上に配置される。また、第２の加熱コイル２３の下に送風空間４１を挟んで基板ケースカバー３９が位置することとなる。
【００２６】
４２は第２の加熱コイル２３の中央に位置する円形の通風穴であり、通風穴４２より小さい温度検知部４３が通風穴４２の中心から偏心して通風穴４２の一部を塞ぐ位置に配置されている。温度検知部４３は通風穴４２の一部を遮蔽する遮蔽突起部を形成する。
【００２７】
前述のように上ヒートシンク３６は上基板２７のシロッコファン３４に近い位置に配置されている。４４は前記基板ケースカバー３９に設けられ、前記第２の加熱コイル２３の通風穴４２下に位置して、概略通風穴４２の直径に近い大きさの略円形の第１の貫通穴であり、第１の貫通穴４４の外周には垂直方向でシロッコファン３４の風下側に半円状の第１の送風誘導壁４５が設けてある。第１の送風誘導壁４５は基板ケースカバー３９の天面４０から下方に垂直に伸設されている。４６は第２の貫通穴であり、前記第１の貫通穴４４よりシロッコファン３４側に位置して第２の送風誘導壁４７が第２の貫通穴４６の風下側に設けてある。４８は第３の貫通穴であり、第２の貫通穴４６よりさらにシロッコファン３４側に位置する。４９は第３の貫通穴４８の風下側に設けられた第３の送風誘導壁である。第１の送風誘導壁４５は第２の送風誘導壁４７よりも下方に長く伸設され、第２の送風誘導壁４７は第３の送風誘導壁４９よりも下方に長く伸設されている。また、第１の貫通穴４４は第２の貫通穴４６よりも開口面積は大きく、第２の貫通穴４６は第３の貫通穴４８よりも開口面積は大きい。
【００２８】
第２の加熱コイル２３は、コ字状に形成され上方向に開口したフェライト５０と、このフェライト５０を１２本放射状に配置してインサート成形したＰＰＳ樹脂等で略円盤状に形成された基台５１と、直径０．０５ｍｍの自己融着型エナメル線を約１６００本撚って太い導線５２を形成しこの導線５２で中央を開口した円盤状に熱融着させて成形したコイル５３と、コイル５３を押さえるコイル押さえ５４とを有している。コイル５３は巻き数を増すために２層に巻いてある。巻き方は中心から１層目と２層目とを交互に巻きながら外周へと巻いて行く方法である。
【００２９】
コイル押さえ５４は垂直方向に円筒状に形成しコイル５３外周に位置する壁５５と、壁５５から放射状に中心に向かう４本の押さえ爪５６と、押さえ爪５６の先端付近に下向きに凸な突起５７が設けてある。突起５７以外の押さえ爪５６の伸設部５８はコイル５３には接することなく突起５７のみがコイル５３の上面に当接することとなり、コイル５３と押さえ爪５６との間に約２ｍｍの隙間５９ができる。この隙間５９を冷却風が通過する。
【００３０】
温度検知部４３は、前記基台５１の通風穴４２に下方に向かって伸設された逆円錐形状の防風部材６０の凹状収容部６１と、ＰＰＳ樹脂等で形成され逆円錐形状で前記防風部材６０に固定された温度検知台６２と、サーミスタ等を用いた温度検知素子６３を上面に保持した温度検知ユニット６４と、保持ばね６５とで構成されている。前記温度検知ユニット６４を保持ばね６５で平面プレート１３の下面に押圧して、温度検知素子６３が平面プレート１３の下面に直接当接して平面プレート１３の温度を検知する構成になっている。防風部材６０と温度検知台６２との間には約１ｍｍ幅の空間６６があり、この空間６６が通風穴４２を通過する風による冷却から温度検知素子６３を熱的に断熱する機能がある。
【００３１】
前述のように温度検知部４３を通風穴４２の中心から偏心して位置させることで、シロッコファン３４から送られる風を通風穴４２から第２の加熱コイル２３上面の隙間５９に誘導するときに温度検知部４３の配置を変えることで任意の方向に風を誘導することができる。つまり、第２の加熱コイル２３の上面を放射状に流れる風の強い方向があると、通風穴４２のこの風の強い方向に温度検知部４３を配置することで、通風穴４２からの風が温度検知部４３に邪魔されて弱まる。
【００３２】
一方放射状に流れる風の弱い方向は温度検知部４３に邪魔された風の一部が流入して風が強まり、結果としてシロッコファン３４からの一方向の風を偏心した温度検知部４３を有する通風穴４２を通すことで、第２の加熱コイル２３上面の隙間５９を均等に流すことができて、コイル５３上面を均等に冷却することができるので、コイル５３上面の温度上昇に偏りが無くなる。
【００３３】
また、温度検知部４３で反射された風は第２の加熱コイル２３下面に沿って第２の加熱コイル２３外周に向かって送風空間４１を放射状に流れて、第２の加熱コイル２３下面を均等に冷却することができるのでコイル５３下面の温度上昇に偏りが無くなる。
【００３４】
６７は基台５１にインサート成形で配置されたコ字状のフェライト５０の外周凸部であり、６８はフェライト５０の内周凸部である。フェライト５０は外周凸部６７と内周凸部６８とを上方に向けて、基台５１の外周に均等な角度で放射状に１２個配置されている。外周凸部６７と外周凸部６７との間は比較的低い外周凹部６９が１２カ所形成されている。
【００３５】
ここで、コイル押さえ５４の壁５５には風穴７０が外周に１０箇所設けてある。風穴７０は壁５５を貫通した穴であり、コイル押さえ５４を基台５１にセットすると、基台５１の外周凹部６９の角度に風穴７０が位置するように配置されている。これにより、通風穴４２から第２の加熱コイル２３上面に誘導された風は、押さえ爪５６とコイル５３上面の間の隙間５９を通過して外周凹部６９の外側に位置する風穴７０から第２の加熱コイル２３外方に放散される。風穴７０の高さはコイル５３の高さとほぼ同じ高さである。
【００３６】
７１はリング状導体である第１のリングであり、シリコンゴム被覆電線をリング状にかしめやはんだ等で接続して前記コイル押さえ５４の壁５５内周に沿って配置されている。
【００３７】
第１のリング７１は前記コイル５３と同一中心の円周でコイル５３外周の外側にコイル５３より約３ｍｍ高い位置でコイル５３外周に配置されている。７２はリング状導体である第２のリングであり、シリコンゴム被覆電線をリング状にかしめやはんだ等で接続して前記基台５１の外周溝部７３に沿って前記外周凸部６７外側に設けられた載置リブ７４にセットされて配置されている。
【００３８】
第２のリング７２は前記コイル５３と同一中心の円周でコイル５３外周より外側にコイル５３より約５ｍｍ低い位置にコイル５３外周に配置されている。前述のコイル押さえ５４の風穴７０は第１のリング７１の高さと第２のリング７２の高さとの間に位置し、第１のリング７１と第２のリング７２の外側に位置することとなる。
【００３９】
７５は遮蔽板であり、遮蔽板７５は略円盤状に形成された０．３ｍｍのマイカ板をプレス型で打ち抜いて形成された上遮蔽板７６と、上遮蔽板７６と同じく０．３ｍｍのマイカ板で形成された下遮蔽板７７と、上遮蔽板７６と下遮蔽板７７との間に塗布した導電性塗膜７８と、導電性塗膜７８の両端に電気的に接続されて下向きに伸設した一対の電極７９とを有している。電極７９は電気的に接地されている。導電性塗膜７８は上遮蔽板７６と下遮蔽板７７とで電気的に絶縁されている。上遮蔽板７６と下遮蔽板７７とは接着されている。遮蔽板７５の略中央には前記温度検知部４３の位置に温度検知部４３の外周と同じ大きさの嵌合穴８０が開けてある。遮蔽板７５を押さえ爪５６に載置したときに前記嵌合穴８０が温度検知部４３に嵌合して位置決めになるとともに、加熱コイル２３上面の隙間５９と遮蔽板７５上面の空間とを遮断する。この嵌合穴８０からは前記シロッコファン３４からの送風は遮蔽板７５上方にはほとんど漏れない。この構成により通風穴４２から第２の加熱コイル２３上面に通過した風は遮蔽板７５に上方への進路を阻まれて上昇せずに遮蔽板７５に沿って通風穴４２から放射状に外周へと流れることとなる。
【００４０】
８１は遮蔽板７５の上に位置し前記平面プレート１３の下に密着した非磁性金属板である厚さ１ｍｍのアルミニウム板で形成された略半月状のシールド板である。シールド板８１は２枚を使用してドーナツ状に配置し前記遮蔽板７５上に位置し、シールド板８１の外周から伸設した各々２カ所の曲げ爪８２を曲げて取り付ける。シールド板８１とシールド板８１との間は約１０ｍｍ間隔を開けておく。シールド板８１の投影面は前記コイル５３の投影とほぼ一致する。シールド板８１は下面が前記遮蔽板７５に密着するとともに上面を前記平面プレート１３に密着している。
【００４１】
８３は第２の加熱コイル２３の基台５１外周溝部７３に収納されて固定された透明リングであり、基台５１の外周溝部７３に備えられて水平方向に発光する発光ダイオード８４の光を第２の加熱コイル２３のほぼ外周に沿って光りの輪を上方に放射する。この光の輪は平面プレート１３を介して使用時に第２の加熱コイル２３の位置を知らせて鍋を置く位置を知らせる機能がある。
【００４２】
８５は基台５１の外周近傍に備えられた一対の温度検知センサであり、前記遮蔽板７５の温度を下方から検知する。前記外周凸部６７は第２の加熱コイル２３外周に均等な角度で１２カ所設けてあり、従って外周凹部６９は均一な角度で１２カ所存在する。
【００４３】
一方コイル押さえ５４の壁５５に設けられた外周凹部６９に対応する風穴７０は１０カ所である。残りの２カ所は壁５５に風穴７０が無い状態である。その位置がこの一対の温度検知センサ８５の取付位置である。従って、通風穴４２を通ってコイル５３上面に沿って放射状に放散された風が風穴７０から排気されるときに、温度検知センサ８５上を通過した風は風穴７０が無いので円滑にコイル押さえ５４の外周外方に流れることができない。よって温度検知センサ８５上を通過する風は他の放射状に排気される空気の流れよりも弱い流れとなる。結果として温度検知センサ８５は冷却風の影響が小さく、精度の高い温度検知が可能になる。
【００４４】
８６は基板ケースカバー３９天面４０の第１の加熱コイル２２近傍に開口した分流口である。シロッコファン３４からの送風で上基板２７上を流れた風は上ヒートシンク３６を冷却した後、一部は基板ケースカバー３９上に達し第２の加熱コイル２３を冷却する。基板ケースカバー３９上面へ流れた風以外は基板ケースカバー３９天面４０の下を流れて、分流口８６から第１の加熱コイル２２下面へ送風される。第１の加熱コイル２２は駆動周波数が２０ｋＨｚと比較的低いので分流口８６からの風が第１の加熱コイル２２下面を冷却することで、第１の加熱コイル２２の冷却は充分である。第１の加熱コイル２２を冷却した風は温風となって吸排気グリル１４から後方へ排気される。８７は第２の加熱コイル２３上の平面プレート１３に載置したアルミニウム製の鍋である。
【００４５】
以上のように構成された誘導加熱装置について、図１を用いてその動作を説明する。まず、平面プレート１３の第２の加熱コイル２３上にアルミニウム製鍋８７を載置する。第２の加熱コイル２３に通電する。制御回路２０は第２の加熱コイル２３への通電と同時にシロッコファン３４を駆動する。制御回路２０は通電の負荷電流から鍋８７が非磁性金属製であることを検知する。非磁性金属を検知した制御回路２０は第２の加熱コイル２３へ供給する電源の周波数を６０ｋＨｚにする。
【００４６】
第２の加熱コイル２３から６０ｋＨｚの交番磁界が発生すると、アルミニウム製の鍋８７は底面に電磁誘導により渦電流が発生して加熱される。同時に自身の電流により第２の加熱コイル２３からの磁界に対して反発する磁界が発生する。結果として鍋８７に浮力が発生する。この浮力を低減するために第２の加熱コイル２３が発生する交番磁界中に非磁性金属のシールド板８１を配置するのである。位置は第２の加熱コイル２３と鍋８７との間である。この状態で第２の加熱コイル２３に６０ｋＨｚの交番電流を流すと発生する磁界によりシールド板８１内に渦電流が発生し、この渦電流により発生する磁界に第２の加熱コイル２３からの磁界が反発して第２の加熱コイル２３中心部に磁束が集中する。磁束が集中するために鍋８７の底面では渦電流が発生しジュール熱で鍋８７が加熱される。
【００４７】
ここでシールド板８１がない場合は第２の加熱コイル２３からの磁界が鍋８７底全体に平均に分布するために鍋底に発生するジュール熱が少ない割に磁界は鍋に達しているので浮力は発生する。一方シールド板８１がある場合には一部の磁束はシールド板８１で吸収されるので鍋８７に達する磁束は比較的少ない。従って発生する浮力は比較的少なくなる。
【００４８】
しかし、シールド板８１からの磁界により反発した磁束が鍋８７の中央付近に集中するために表皮効果により鍋８７底で発生するジュール熱は比較的多くなる。結果としてシールド板８１を備えると鍋８７に発生する浮力は低減されるが、発熱量は維持できることとなる。
【００４９】
遮蔽板７５の働きについて説明する。第２の加熱コイル２３と鍋８７底面とは相対する略平面であり電気的にはコンデンサを形成することとなる。６０ｋＨｚで第２の加熱コイル２３を駆動した場合は、このコンデンサの一方の電極である第２の加熱コイル２３に交番電流を流すので交番電界をかけることになり、鍋８７底に電位が発生する。この電位の発生した鍋８７に人間が触れると感電するのでこの電界を遮蔽する必要がある。鍋８７底を接地すればよいが現実的ではない。そこで鍋８７底に変わる遮蔽板７５の導電性塗膜７８を第２の加熱コイル２と鍋８７底との間に位置させて第２の加熱コイル２３と導電性塗膜７８とでコンデンサを形成する。第２の加熱コイル２３の交番電界によって導電性塗膜７８に電位が発生しても電極７９を介して接地されているので鍋８７底に電位が発生することはない。
【００５０】
第２の加熱コイル２３に２０ｋＨｚの交番電流を供給する場合は周波数が比較的低いので鍋８７底に人間が感じる程度の電位が発生するまでには至らない。第１の加熱コイル２２の場合も２０ｋＨｚの交番電流を供給するので同じである。
【００５１】
第２の加熱コイル２３に６０ｋＨｚの交番電流を供給する場合は、シールド板８１には渦電流によって若干の発熱がある。シールド板８１の上面は平面プレート１３に密着しているので熱伝導により平面プレート１３を介して空中へ放熱する。
【００５２】
鍋８７の加熱に伴いコイル５３も自己発熱して温度が上昇する。シロッコファン３４は吸排気グリル１４から吸入して空気を送風口３５から上基板２７、中基板２９下基板３１へ送風する。上基板２７へ送風された空気は最初に上ヒートシンク３６を冷却する。
【００５３】
さらに上基板２７上を進むと風の一部は第３の送風誘導壁４９にぶつかって第３の貫通穴４８を通過して基板ケースカバー３９天面４０の上の送風空間４１に吹き上げられる。
【００５４】
また、風の一部は第２の送風誘導壁４７にぶつかって第２の貫通穴４６を通過して基板ケースカバー３９の上面の送風空間４１に吹き上げられる。最後に第１の送風誘導壁４５にぶつかって第１の貫通穴４４を吹き上がって基板ケースカバー３９上に達し、第２の加熱コイル２３の通風穴４２に達する。
【００５５】
ここで一部の風は温度検知部４３に遮られて第２の加熱コイル２３下面の送風空間４１を通風穴４２を中心に放射状に放散される。通風穴４２を通過した風は遮蔽板７５にぶつかって遮蔽板７５下面を放射状に放散される。この風の流れはやがてコイル押さえ５４の押さえ爪５６とコイル５３の間の隙間５９を通過してコイル５３を冷却しながらコイル押さえ５４の壁５５に達する。壁５５に達した風は第１のリング７１と第２のリング７２の間を通過して外周凸部６７の間の外周凹部６９を通過して１０カ所ある壁５５の風穴７０を通過して第２の加熱コイル２３外方へ放散される。通風穴４２を通過するときにシロッコファン３４からの風は第１の送風誘導壁４５にぶつかって風下に強く流れようとする。
【００５６】
しかし、通風穴４２の風下側には温度検知部４３が設けてあるので、温度検知部４３にぶつかった風の一部が第２の加熱コイル２３下面に流れるとともに、通風穴４２を通って第２の加熱コイル２３上面に流れる風は通風穴４２の風下に位置する温度検知部４３によって風下側の風が弱くなり、温度検知部４３にぶつかった風が風上側に跳ね返るので通風穴４２を通過した時点で第２の加熱コイル２３の上面を均等な強さで放射状に放散される風の流れになる。従って隙間５９を放射状に均等な風が通風穴４２から風穴７０まで障害物がなく円滑にコイル５３上面を流れることとなり、コイル５３の冷却を効率的に行うことが出来る。温度検知部４３の下部の防風部材６０は逆円錐形状なので冷却風が第２の加熱コイル２３上面と下面とに分離する際に圧損を少なく少なくすることができる。
【００５７】
第２の加熱コイル２３下面では第３の貫通穴４８と第２の貫通穴４６と第１の貫通穴４４とから吹き上げて通風穴４２を通過しなかった風が第２の加熱コイル２３下を放射状に放散されてコイル５３下面を冷却しながら第２の加熱コイル２３外方へ放散される。このとき第２の貫通穴４６と第３の貫通穴４８を通過した風が第１の貫通穴４４を通過した風と合流して全体として第２の加熱コイル２３の下面を流れる冷却風は放射状に均等に流れることとなり、第２の加熱コイル２３の冷却を効率的に行うことができる。
【００５８】
鍋８７が磁性金属製である場合は、例えばホーロー鍋等であれば、制御回路２０は負荷電流から判断して第２の加熱コイル２３に２０ｋＨｚの交番電流を供給する。２０ｋＨｚの磁界ではシールド板８１にはほとんど渦電流は発生しないのでシールド板８１の発熱は問題にはならない。
【００５９】
以上にように本実施例によれば、基板ケースカバー３９の第１の貫通穴４４を通風穴４２の下に設けるとともに、通風穴４２に温度検知部４３を設け、遮蔽板７５とコイル５３との間に隙間５９を設けることで、第２の加熱コイル２３上面の冷却を第２の加熱コイル２３の中心である通風穴４２からの均等な放射状冷却風で効率的に行うことが出来るとともに、第２の貫通穴４６と第３の貫通穴４８とを設けることで第２の加熱コイル２３下面の冷却を第２の加熱コイル２３の中心から放射状に均等に冷却することができ、第２の加熱コイル２３の上面と下面の両方を同時にしかも放射状に均等に冷却することができる。
【００６０】
（実施例２）
以下本発明の第２の実施例について、図面を参照しながら説明する。図７において、平面プレート１３、第２の加熱コイル２３、上基板２７、上基板ケース２８、上ヒートシンク３６、送風空間４１、基板ケースカバー３９、天面４０、通風穴４２、温度検知部４３、第１の貫通穴４４、第１の送風誘導壁４５、第２の貫通穴４６、第２の送風誘導壁４７、第３の貫通穴４８、第３の送風誘導壁４９、フェライト５０、基台５１、コイル５３、コイル押さえ５４、壁５５、押さえ爪５６、突起５７、伸設部５８、隙間５９、防風部材６０、凹状収容部６１、温度検知台６２、温度検知素子６３、温度検知ユニット６４、保持ばね６５、空間６６、外周凸部６７、内周凸部６８、外周凹部６９、風穴７０、第１のリング７１、第２のリング７２、外周溝部７３、載置リブ７４、導電性塗膜７８、電極７９、透明リング８３、は実施例１と同一の機能と形状であり、同一の符号を使用する。
【００６１】
図１の構成と異なるのは非磁性金属板であるシールド板９０の上面に高さが２ｍｍの当て突起部９１を複数設けたことと、遮蔽板９２の嵌合穴９３を通風穴４２よりも大きい面積で開口した点である。突起部９１を設けたためにシールド板９０と平面プレート１３との密着がなくなり、シールド板９０と平面プレート１３との間に約２ｍｍの隙間９４が発生する。
【００６２】
また、嵌合穴９３を大きくすることで、通風穴４２から吹き上げる風が嵌合穴９３を通過してシールド板９０まで達することができる。
【００６３】
上記のように構成された誘導加熱装置について、以下その動作を説明する。まず、シロッコファン３４からの風が通風穴４２を通過するまでは実施例１と同じである。また、第２の加熱コイル２３下面で放散される風の動きも実施例１と同じである。
【００６４】
通風穴４２を通過した風について、嵌合穴９３を通過した風は温度検知部４３にぶつかって一部は遮蔽板９２下面に沿ってコイル５３上面を冷却しながら放射状に放散される。嵌合穴９３を通過した風はシールド板９０の中央を通過して平面プレート１３にぶつかって、シールド板９０と平面プレート１３との間の隙間９４を外周方向へ平面プレート１３下面に沿って放射状に放散される。このときシールド板９０と平面プレート１３の下面を冷却しながら放射状に放散されることとなる。
【００６５】
以上のように、通風穴４２を通過した風をシールド板９０と平面プレート１３との間に設けた隙間９４を通過させることにより、シールド板９０や平面プレート１３の冷却を行うことができる。
【００６６】
なお、第１の実施例において第２の加熱コイル２３のコイル５３を２層にしたが、ターン数を増やすために３層や４層にしても良い。また、第２の実施例では、平面プレート１３とシールド板９０との間に隙間９４を設けたが、シールド板９０と遮蔽板９２との間に隙間９４を設けても良いし、遮蔽板９２とコイル押さえ５４との間に隙間９４を設けても良いことは言うまでもない。
【００６７】
【発明の効果】
以上のように本発明によれば、加熱コイルの下面と上面を中央から均等な放射状の冷却風で効率的に冷却することができる優れた誘導加熱装置を実現できるものである。
【図面の簡単な説明】
【図１】本発明の実施例１における第２の加熱コイルの部分断面図
【図２】本発明の実施例１における誘導加熱装置の分解斜視図
【図３】本発明の実施例１における誘導加熱装置の制御部の斜視図
【図４】本発明の実施例１における誘導加熱装置の平面図
【図５】本発明の実施例１における第２の加熱コイルの部分斜視図
【図６】本発明の実施例１における第２の加熱コイルの部分斜視図
【図７】本発明の実施例２における第２の加熱コイルの部分断面図
【符号の説明】
１３平面プレート
２３第２の加熱コイル（加熱コイル）
３４シロッコファン（送風装置）
４２通風穴
４３温度検知部
４５第１の送風誘導壁
４７第２の送風誘導壁
４９第３の送風誘導壁
５０フェライト
５１基台
５３コイル
５４コイル押さえ
５５壁
５６押さえ爪
５８伸設部（押さえ爪本体）
５９隙間
６０防風部材
６７外周凸部
７０風穴
７１第１のリング（リング状導体）
７２第２のリング（リング状導体）
７５遮蔽板
８１シールド板（非磁性金属板）
９０シールド板（非磁性金属板）
９２遮蔽板
９４隙間[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction heating apparatus that performs metal cooking or the like mainly for cooking at home or for business use.
[0002]
[Prior art]
In the conventional induction heating apparatus, the lower surface of the heating coil is mainly cooled, or the lower surface of the heating coil is mainly cooled from the side surface (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Application No. 2001-260753 (Figs. 3-5)
[0004]
[Problems to be solved by the invention]
In order to heat a pan such as copper or aluminum, a high frequency current of 40 to about 100 kHz, which is higher than about 20 kHz or about 30 kHz suitable for an iron pan, must be passed through the heating coil. In addition, a high output induction heating apparatus is desired. The higher the frequency, the higher the effective resistance due to the skin effect and the greater the heat generation. Further, when the current value is increased, the self-heating of the heating coil is also increased. As described above, in order to improve the performance of the induction heating apparatus, it is required to efficiently cool the heating coil.
[0005]
An object of this invention is to provide the induction heating apparatus which can cool both the upper surface and lower surface of a heating coil simultaneously from the center of a heating coil to the outer periphery direction.
[0006]
[Means for Solving the Problems]
In order to solve this problem, in order to efficiently cool a heating coil that generates a large amount of heat, the cooling air is branched and guided to the upper surface of the heating coil through a ventilation hole located in the center of the heating coil, and Cooling air is passed radially from the center through the gap between the flat plate and the heating coil, and the lower surface of the heating coil can be cooled. Formed in the ventilation hole through the temperature detector with a windproof member extending downward Made.
[0007]
As a result, an induction heating device can be obtained that can sufficiently cool even if a higher frequency current is passed through the heating coil or the value of the current passed through the heating coil is increased to increase the heat generation of the heating coil. In particular, it becomes possible to heat a nonmagnetic metal.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention includes a flat plate on which an object to be heated is placed, and a position below the flat plate. However, it is almost donut-shaped and has a vent hole in the center. Heating coil, gap provided between the flat plate and the heating coil, a blower, and the blower generated below the heating coil. cooling Induct a part of the wind from the lower center of the heating coil upward Said cooling A ventilation guide wall for guiding wind ,in front The air blowing guide wall Ventilation hole Before being guided to Cold In order to flow the draft evenly radially from the center of the ventilation hole to the lower surface of the heating coil and the gap A windproof member extending downward Temperature detector In the ventilation hole It is formed and has the effect | action that the upper and lower surfaces of a heating coil can be cooled.
[0009]
The invention described in claim 2 A flat plate on which an object to be heated is placed; a heating coil positioned below the flat plate, having a substantially donut shape and having a ventilation hole in the center; a gap provided between the flat plate and the heating coil; and a blower And a ventilation guide wall for guiding a part of the cooling air generated by the air blower located below the heating coil and guiding the cooling air upward from a substantially lower center of the heating coil, The cooling air guided to the ventilation hole by the air blowing guide wall is caused to flow evenly and radially from the center of the ventilation hole to the lower surface of the heating coil and the gap. Eccentric from the center of the ventilation hole Temperature detector It was designed to be arranged, and the air flow was passed at the same time as passing through a part of the ventilation hole above the heating coil. cooling The direction in which the wind flows can be controlled, and the temperature detection unit has an effect of branching the air flow below the heating coil and controlling the amount of wind that branches downward depending on the position and area of the temperature detection unit.
[0010]
The invention according to claim 3 , Covered A flat plate on which a heated object is placed; a heating coil located below the flat plate; a gap provided between the flat plate and the heating coil; a blower; and the blower located below the heating coil. Equipment is generated cooling Induct a part of the wind from the lower center of the heating coil upward Said cooling A blowing induction wall for guiding wind, and the heating coil is substantially donut-shaped and has a ventilation hole in the center, cooling An induction heating apparatus configured to pass a part of wind through the gap between the flat plate and the heating coil, the heating coil is a base, Coil and said Ferrite arranged radially from the center of the coil and coil retainer, the coil retainer Said A wall covering the outer periphery of the coil and a plurality of pressing claws extending from the wall to the top surface of the coil, and having air holes in the wall, are guided above the heating coil. cooling The air is diffused radially and diffused radially from the top surface of the heating coil, thereby enabling efficient cooling.
[0011]
The invention according to claim 4 is a flat plate on which an object to be heated is placed, a heating coil positioned below the flat plate, a gap provided between the flat plate and the heating coil, a blower device, The blower is generated below the heating coil. cooling Induct a part of the wind from the lower center of the heating coil upward Said cooling A blowing induction wall for guiding wind, and the heating coil is substantially donut-shaped and has a ventilation hole in the center, cooling An induction heating apparatus configured to pass a part of wind through the gap between the flat plate and the heating coil, the heating coil is a base, Coil and said A U-shaped ferrite that is arranged radially from the center of the coil and opened, and a coil presser, the coil presser being located on the outer periphery of the heating coil, and a wall that covers the outer periphery of the U-shaped ferrite placement; A plurality of pressing claws extending from the wall to the upper surface of the coil, and an inner peripheral convex portion of the U-shaped ferrite But The coil is positioned so as to be located on the inner side of the inner periphery of the coil, and the outer peripheral convex portion is located on the outer side of the outer periphery of the coil, and the wall of the coil retainer has an air hole. And other convex protrusions of the U-shaped ferrite of It has a structure provided between them, and the wind induced above the heating coil is diffused radially and diffused radially from the top surface of the heating coil to enable efficient cooling and at the same time as the height of the ferrite. Now, the air hole can be formed and the heating coil having a compact height can be designed.
[0012]
The invention according to claim 5 is configured such that two ring-shaped conductors are separated in the vertical direction on the outer periphery of the heating coil and arranged substantially in parallel, and an air hole is located between the upper and lower ring-shaped conductors. Induced above the heating coil cooling The air is diffused radially and diffused radially from the top surface of the heating coil, thereby enabling efficient cooling.
[0013]
In the invention according to claim 6, a shielding plate is disposed between the upper portion of the heating coil and the flat plate, The shielding plate is From the vent hole Of the heating coil Blocking the path of the wind guided to the top surface of the coil to the upper side of the shielding plate, Said Between the top of the coil Said It is configured to diffuse to the outer periphery of the heating coil, branching from the ventilation hole above the heating coil cooling It has the effect | action that it suppresses a wind with a shielding board and diffuses it radially at the upper part of a heating coil, and can cool the heating coil upper surface efficiently.
[0014]
In the invention according to claim 7, the coil presser has a plurality of presser claws extending from the wall toward the center, and a downwardly projecting protrusion extending near the tip of the presser pawl, and the protrusion abuts the coil. The presser claw body is configured to be positioned away from the coil, and has an effect of efficiently cooling the upper surface of the heating coil.
[0015]
According to the eighth aspect of the present invention, a shielding plate is disposed between the upper portion of the heating coil and the flat plate, a nonmagnetic metal plate is disposed between the shielding plate and the planar plate, and the heating coil and the shielding plate are disposed between. Or at least one between the shielding plate and the non-magnetic metal plate or between the non-magnetic metal plate and the flat plate, Of the heating coil Induced on top of coil cooling Blocking the path of the wind upward to the shielding plate, Cooling air It is configured to diffuse to the outer periphery of the heating coil through the gap, and an arbitrary gap is provided between the heating coil, the heat shield plate, the non-magnetic metal plate, and the flat plate so that the cooling air from the ventilation hole is a gap. It has the effect | action that the arbitrary components located above a coil can be cooled by letting it pass.
[0016]
According to the ninth aspect of the present invention, the control circuit for driving the heating coil is formed by an inverter circuit, and the inverter circuit is configured to be able to heat a non-magnetic metal having high conductivity and low resistance such as aluminum or copper. Even when the heating coil generates a large amount of heat, it has the effect of uniformly cooling the upper and lower surfaces of the heating coil.
[0017]
【Example】
Example 1
Embodiments of the present invention will be described below with reference to the drawings.
[0018]
Reference numeral 11 denotes a rectangular parallelepiped outline formed of a metal plate and having an open top. Reference numeral 12 denotes a top frame formed of a metal plate fixed so as to close the upper portion of the outer shell, and a flat plate 13 formed of a rectangular heat-resistant glass plate is attached to the top frame 12 so that the outer periphery thereof is the top frame 12. Bonded and watertight. The flat plate 13 is designed to place a pan or the like. Reference numeral 14 denotes an intake / exhaust grill disposed laterally behind the top frame 12, which has a large number of ventilation holes 15 and is detachably mounted on the top frame 12. Reference numeral 16 denotes a hook for fixing the top frame 12 to the front part of the outer shell 11.
[0019]
Reference numeral 17 denotes a roaster disposed on the left side of the outer shell 11, which is used by pulling out the handle 18. The roaster 17 is heated by a sheathed heater (not shown). Reference numeral 19 denotes a circuit unit in which the control circuit 20 is accommodated. Reference numeral 21 denotes an operation unit which has a structure in which the lower part of the front surface is pivotally supported and tilted forward and protruded when used.
[0020]
22 is the 1st heating coil arrange | positioned at the left part of the outer shell 11, and has a heating capability of a maximum of 3 kW by induction heating. The first heating coil 22 is driven by a power source having a frequency of about 20 kHz and heats a pan or the like made of magnetic metal. Reference numeral 23 denotes a second heating coil arranged on the right part of the outer shell 11. The second heating coil 23 has a heating capacity of about 2 kW. The second heating coil 23 is driven by a power source having a frequency of about 20 kHz or about 60 kHz depending on the type of metal. Whether the type of metal such as a pan placed on the upper flat plate 13 of the second heating coil 23 is a magnetic metal or a nonmagnetic metal is determined from the load current of the second heating coil 23 and the frequency of the drive power supply. To decide. In the case of magnetic metal, the frequency is 20 kHz. In the case of non-magnetic metal, the frequency is 60 kHz.
[0021]
The control circuit 20 includes an inverter circuit that supplies a current having a frequency of about 20 kHz to the first heating coil 22 and supplies a current having a frequency of about 20 kHz and about 60 kHz to the second heating coil 23.
[0022]
Reference numeral 24 denotes three first support springs that support the first heating coil 22. Reference numeral 25 denotes three second support springs that support the second heating coil 23. 26 is a disk-shaped quick radiant heater located in the center back of the 1st heating coil 22 and the 2nd heating coil 23, and has a function which heats a glass pot, a clay pot, etc. FIG.
[0023]
The circuit unit 19 will be described. An upper substrate 27 for controlling the second heating coil 23, an upper substrate case 28 for accommodating the upper substrate 27, an intermediate substrate 29 for controlling the first heating coil 22, and an intermediate substrate case 30 for accommodating the intermediate substrate 29; A lower substrate 31 that generates power to be supplied to the second heating coil 23 and a lower substrate case 32 that stores the lower substrate 31 are stacked in order from the top in the horizontal direction and stored in the circuit unit 19. The circuit portion 19 is formed with a storage portion 33 located on the right rear side of the outer shell 11.
[0024]
Reference numeral 34 denotes a vertical sirocco fan forming a blower, which is housed in the housing part 33 of the circuit part 19 and blows air to the circuit part 19. Each of the upper substrate 27, the middle substrate 29, and the lower substrate 31 is close to the air blowing port 35 of the sirocco fan 34, the upper substrate 27 has an upper heat sink 36, the middle substrate 29 has a middle heat sink 37, and the lower substrate 31 has The lower heat sink 38 is positioned respectively, and the heat sinks 36, 37, and 38 that generate a large amount of heat on the respective substrates 27, 29, and 31 are first cooled.
[0025]
Reference numeral 39 denotes a substrate case cover positioned on the upper substrate case 28, and the second support spring 25 is positioned above the substrate case cover 39. The substrate case cover 39 has a top surface 40 and has a substantially rectangular box shape, and is disposed on the upper substrate case 28 and the sirocco fan 34. Further, the substrate case cover 39 is positioned under the second heating coil 23 with the air blowing space 41 interposed therebetween.
[0026]
Reference numeral 42 denotes a circular ventilation hole located at the center of the second heating coil 23, and the temperature detection unit 43 smaller than the ventilation hole 42 is arranged at a position that is eccentric from the center of the ventilation hole 42 and blocks a part of the ventilation hole 42. ing. The temperature detection unit 43 forms a shielding projection that shields a part of the ventilation hole 42.
[0027]
As described above, the upper heat sink 36 is disposed at a position near the sirocco fan 34 on the upper substrate 27. 44 is a substantially circular first through hole which is provided in the substrate case cover 39 and is located below the ventilation hole 42 of the second heating coil 23 and has a size close to the diameter of the approximate ventilation hole 42; A semicircular first air blowing guide wall 45 is provided on the outer periphery of the first through hole 44 in the vertical direction on the leeward side of the sirocco fan 34. The first air blowing guide wall 45 extends vertically downward from the top surface 40 of the substrate case cover 39. Reference numeral 46 denotes a second through hole, and a second air blowing guide wall 47 is provided on the leeward side of the second through hole 46 and is located closer to the sirocco fan 34 than the first through hole 44. Reference numeral 48 denotes a third through hole, which is located further on the sirocco fan 34 side than the second through hole 46. Reference numeral 49 denotes a third air blowing guide wall provided on the leeward side of the third through hole 48. The first air blowing guide wall 45 extends longer than the second air blowing guide wall 47, and the second air blowing guide wall 47 extends longer than the third air blowing guide wall 49. Further, the opening area of the first through hole 44 is larger than that of the second through hole 46, and the opening area of the second through hole 46 is larger than that of the third through hole 48.
[0028]
The second heating coil 23 is formed in a substantially disk shape with a ferrite 50 formed in a U shape and opened upward, and PPS resin or the like formed by insert-molding 12 ferrite 50 radially. 51, a coil 53 formed by twisting approximately 1600 self-bonding enamel wires having a diameter of 0.05 mm to form a thick conducting wire 52 and thermally fusing it into a disk shape having an opening at the center, and a coil And a coil presser 54 for pressing 53. The coil 53 is wound in two layers in order to increase the number of turns. The winding method is a method in which the first layer and the second layer are alternately wound from the center around the outer periphery.
[0029]
The coil retainer 54 is formed in a cylindrical shape in the vertical direction and has a wall 55 positioned on the outer periphery of the coil 53, four retainer claws 56 radially extending from the wall 55 toward the center, and a protrusion projecting downward near the tip of the retainer claw 56. 57 is provided. The extending portion 58 of the pressing claw 56 other than the projection 57 does not contact the coil 53, and only the projection 57 comes into contact with the upper surface of the coil 53, and a gap 59 of about 2 mm is formed between the coil 53 and the pressing claw 56. it can. Cooling air passes through the gap 59.
[0030]
The temperature detection unit 43 includes a concave accommodating portion 61 of a reverse-cone-shaped windproof member 60 extended downward in the ventilation hole 42 of the base 51 and a reverse-conical shape formed of PPS resin or the like. The temperature detection unit 62 is fixed to the temperature detection unit 62, the temperature detection unit 64 using a thermistor or the like is held on the upper surface, and the holding spring 65. The temperature detection unit 64 is pressed against the lower surface of the flat plate 13 by the holding spring 65, and the temperature detection element 63 directly contacts the lower surface of the flat plate 13 to detect the temperature of the flat plate 13. There is a space 66 having a width of about 1 mm between the windproof member 60 and the temperature detection table 62, and this space 66 has a function of thermally insulating the temperature detection element 63 from cooling by the wind passing through the ventilation holes 42.
[0031]
As described above, the temperature detector 43 is positioned eccentrically from the center of the ventilation hole 42, so that the temperature sent when the wind sent from the sirocco fan 34 is guided from the ventilation hole 42 to the gap 59 on the upper surface of the second heating coil 23. The wind can be guided in an arbitrary direction by changing the arrangement of the detection unit 43. That is, when there is a strong direction of the wind flowing radially on the upper surface of the second heating coil 23, the temperature from the ventilation hole 42 is increased by arranging the temperature detection unit 43 in the strong direction of the ventilation hole 42. It is disturbed by the detector 43 and weakens.
[0032]
On the other hand, in the direction where the wind that flows radially is weak, a part of the wind disturbed by the temperature detection unit 43 flows in and the wind is strengthened. By passing the air holes 42, the gaps 59 on the upper surface of the second heating coil 23 can be evenly flowed, and the upper surface of the coil 53 can be cooled uniformly, so that the temperature rise on the upper surface of the coil 53 is not biased.
[0033]
In addition, the wind reflected by the temperature detector 43 flows radially along the lower surface of the second heating coil 23 toward the outer periphery of the second heating coil 23, and the lower surface of the second heating coil 23 is evenly distributed. Therefore, the temperature rise on the lower surface of the coil 53 is not biased.
[0034]
Reference numeral 67 denotes an outer peripheral convex portion of the U-shaped ferrite 50 arranged on the base 51 by insert molding, and 68 denotes an inner peripheral convex portion of the ferrite 50. Twelve ferrites 50 are radially arranged at an equal angle on the outer periphery of the base 51 with the outer peripheral convex portion 67 and the inner peripheral convex portion 68 facing upward. Twelve relatively low peripheral recesses 69 are formed between the peripheral protrusions 67 and the peripheral protrusions 67.
[0035]
Here, ten air holes 70 are provided on the outer periphery of the wall 55 of the coil retainer 54. The air hole 70 is a hole that penetrates the wall 55, and is arranged so that the air hole 70 is positioned at an angle of the outer peripheral recess 69 of the base 51 when the coil retainer 54 is set on the base 51. As a result, the wind guided from the ventilation hole 42 to the upper surface of the second heating coil 23 passes through the gap 59 between the presser claw 56 and the upper surface of the coil 53 and passes through the air hole 70 positioned outside the outer peripheral recess 69. The heat coil 23 is diffused outside. The height of the air hole 70 is substantially the same as the height of the coil 53.
[0036]
Reference numeral 71 denotes a first ring which is a ring-shaped conductor, which is arranged along the inner periphery of the wall 55 of the coil retainer 54 by connecting the silicon rubber-coated wires in a ring shape by caulking or soldering.
[0037]
The first ring 71 is arranged on the outer periphery of the coil 53 at a position about 3 mm higher than the coil 53 on the outer periphery of the coil 53 on the same center circumference as the coil 53. Reference numeral 72 denotes a second ring which is a ring-shaped conductor, and is provided outside the outer peripheral convex portion 67 along the outer peripheral groove portion 73 of the base 51 by connecting a silicon rubber-coated electric wire in a ring shape by caulking or soldering. It is set and arranged on the mounting rib 74.
[0038]
The second ring 72 is arranged on the outer periphery of the coil 53 at a position having a circumference of the same center as the coil 53 and outside the outer periphery of the coil 53 and about 5 mm lower than the coil 53. The aforementioned air hole 70 of the coil retainer 54 is located between the height of the first ring 71 and the height of the second ring 72, and is located outside the first ring 71 and the second ring 72. .
[0039]
Reference numeral 75 denotes a shielding plate. The shielding plate 75 is formed by punching out a 0.3 mm mica plate formed in a substantially disc shape with a press die, and a mica of 0.3 mm, which is the same as the upper shielding plate 76. A lower shielding plate 77 formed of a plate, a conductive coating film 78 applied between the upper shielding plate 76 and the lower shielding plate 77, and electroconductive coating film 78 at both ends of the conductive coating film 78. spirit And a pair of electrodes 79 extending downward. The electrode 79 is electrically grounded. The conductive coating 78 is electrically insulated by the upper shielding plate 76 and the lower shielding plate 77. The upper shielding plate 76 and the lower shielding plate 77 are bonded. A fitting hole 80 having the same size as the outer periphery of the temperature detection unit 43 is formed at the position of the temperature detection unit 43 in the approximate center of the shielding plate 75. When the shielding plate 75 is placed on the presser claw 56, the fitting hole 80 is fitted to the temperature detecting portion 43 for positioning, and the clearance 59 on the upper surface of the heating coil 23 and the space on the upper surface of the shielding plate 75 are blocked. To do. Air from the sirocco fan 34 hardly leaks above the shielding plate 75 from the fitting hole 80. With this configuration, the wind that has passed from the ventilation hole 42 to the upper surface of the second heating coil 23 is prevented from going upward due to the shielding plate 75, and rises radially from the ventilation hole 42 along the shielding plate 75 to the outer periphery. It will flow.
[0040]
Reference numeral 81 denotes a substantially half-moon shaped shield plate formed of an aluminum plate having a thickness of 1 mm, which is a nonmagnetic metal plate located on the shield plate 75 and in close contact with the flat plate 13. Two shield plates 81 are arranged in a donut shape using two sheets, positioned on the shielding plate 75, and bent by two bending claws 82 extending from the outer periphery of the shield plate 81. An interval of about 10 mm is provided between the shield plate 81 and the shield plate 81. The projection surface of the shield plate 81 substantially coincides with the projection of the coil 53. The shield plate 81 has a lower surface in close contact with the shield plate 75 and an upper surface in close contact with the flat plate 13.
[0041]
Reference numeral 83 denotes a transparent ring which is housed and fixed in the outer peripheral groove 73 of the base 51 of the second heating coil 23. The transparent ring 83 is provided in the outer peripheral groove 73 of the base 51 and emits light from the light emitting diode 84 which emits light in the horizontal direction. A ring of light is radiated upward along substantially the outer periphery of the two heating coils 23. This ring of light has a function of notifying the position of the second heating coil 23 during use through the flat plate 13 and notifying the position where the pan is placed.
[0042]
85 is a pair of temperature detection sensors provided near the outer periphery of the base 51, and detects the temperature of the shielding plate 75 from below. The outer peripheral protrusions 67 are provided at 12 positions at an equal angle on the outer periphery of the second heating coil 23, and therefore the outer peripheral recesses 69 are present at 12 positions at a uniform angle.
[0043]
On the other hand, there are 10 air holes 70 corresponding to the outer peripheral recesses 69 provided in the wall 55 of the coil retainer 54. The remaining two places are in a state where there is no air hole 70 in the wall 55. That position is the mounting position of the pair of temperature detection sensors 85. Therefore, when the wind radially radiated along the upper surface of the coil 53 through the ventilation hole 42 is exhausted from the ventilation hole 70, the wind passing over the temperature detection sensor 85 does not have the ventilation hole 70. Cannot flow outside the outer periphery of the. Therefore, the wind passing over the temperature detection sensor 85 becomes a weaker flow than the flow of other radially exhausted air. As a result, the temperature detection sensor 85 is less affected by the cooling air and enables highly accurate temperature detection.
[0044]
Reference numeral 86 denotes a diversion port opened near the first heating coil 22 on the top surface 40 of the substrate case cover 39. The wind that has flowed over the upper substrate 27 by blowing air from the sirocco fan 34 cools the upper heat sink 36, and then partly reaches the substrate case cover 39 to cool the second heating coil 23. Except for the wind that has flowed to the upper surface of the substrate case cover 39, it flows below the top surface 40 of the substrate case cover 39 and is blown from the diversion port 86 to the lower surface of the first heating coil 22. Since the driving frequency of the first heating coil 22 is relatively low at 20 kHz, the first heating coil 22 is sufficiently cooled by the wind from the diversion port 86 cooling the lower surface of the first heating coil 22. The air that has cooled the first heating coil 22 becomes warm air and is exhausted rearward from the intake / exhaust grill 14. Reference numeral 87 denotes an aluminum pan placed on the flat plate 13 on the second heating coil 23.
[0045]
About the induction heating apparatus comprised as mentioned above, the operation | movement is demonstrated using FIG. First, the aluminum pan 87 is placed on the second heating coil 23 of the flat plate 13. The second heating coil 23 is energized. The control circuit 20 drives the sirocco fan 34 simultaneously with energization of the second heating coil 23. The control circuit 20 detects that the pan 87 is made of nonmagnetic metal from the energized load current. The control circuit 20 that has detected the nonmagnetic metal sets the frequency of the power supplied to the second heating coil 23 to 60 kHz.
[0046]
When an alternating magnetic field of 60 kHz is generated from the second heating coil 23, the aluminum pan 87 is heated by generating an eddy current on the bottom surface by electromagnetic induction. At the same time, a magnetic field that repels the magnetic field from the second heating coil 23 is generated by its own current. As a result, buoyancy is generated in the pan 87. In order to reduce this buoyancy, a nonmagnetic metal shield plate 81 is disposed in an alternating magnetic field generated by the second heating coil 23. The position is between the second heating coil 23 and the pan 87. In this state, an eddy current is generated in the shield plate 81 by a magnetic field generated when an alternating current of 60 kHz is passed through the second heating coil 23, and a magnetic field from the second heating coil 23 is generated in the magnetic field generated by the eddy current. Repulsion concentrates the magnetic flux on the center of the second heating coil 23. Since the magnetic flux concentrates, an eddy current is generated on the bottom surface of the pan 87 and the pan 87 is heated by Joule heat.
[0047]
Here, when there is no shield plate 81, the magnetic field from the second heating coil 23 is averagely distributed over the entire bottom of the pan 87, so that the magnetic field reaches the pan even though the Joule heat generated at the bottom of the pan is small. appear. On the other hand, when there is the shield plate 81, a part of the magnetic flux is absorbed by the shield plate 81, so that the magnetic flux reaching the pan 87 is relatively small. Therefore, the generated buoyancy is relatively small.
[0048]
However, since the magnetic flux repelled by the magnetic field from the shield plate 81 is concentrated near the center of the pan 87, the Joule heat generated at the bottom of the pan 87 due to the skin effect becomes relatively large. As a result, when the shield plate 81 is provided, the buoyancy generated in the pan 87 is reduced, but the calorific value can be maintained.
[0049]
The function of the shielding plate 75 will be described. The second heating coil 23 and the bottom surface of the pan 87 are substantially flat surfaces facing each other, and form a capacitor electrically. When the second heating coil 23 is driven at 60 kHz, an alternating current is applied to the second heating coil 23 that is one electrode of this capacitor, so that an alternating electric field is applied, and a potential is generated at the bottom of the pan 87. . It is necessary to shield this electric field because an electric shock is received when a human touches the pot 87 where this electric potential is generated. The bottom of the pan 87 may be grounded, but it is not realistic. Therefore, the conductive coating film 78 of the shielding plate 75 that changes to the bottom of the pan 87 is positioned between the second heating coil 2 and the bottom of the pan 87, and a capacitor is formed by the second heating coil 23 and the conductive coating film 78. To do. Even if a potential is generated in the conductive coating film 78 by the alternating electric field of the second heating coil 23, the potential is not generated at the bottom of the pan 87 because it is grounded through the electrode 79.
[0050]
In the case where an alternating current of 20 kHz is supplied to the second heating coil 23, the frequency is relatively low, so that a potential that is felt by humans is not generated at the bottom of the pan 87. The same applies to the first heating coil 22 because an alternating current of 20 kHz is supplied.
[0051]
When an alternating current of 60 kHz is supplied to the second heating coil 23, the shield plate 81 has a slight heat generation due to the eddy current. Since the upper surface of the shield plate 81 is in close contact with the flat plate 13, heat is radiated to the air via the flat plate 13 by heat conduction.
[0052]
As the pan 87 is heated, the coil 53 also generates heat and the temperature rises. The sirocco fan 34 sucks from the intake / exhaust grill 14 and blows air from the blower opening 35 to the upper substrate 27 and the middle substrate 29 and the lower substrate 31. The air blown to the upper substrate 27 first cools the upper heat sink 36.
[0053]
When the air further travels on the upper substrate 27, part of the wind hits the third air blowing guide wall 49, passes through the third through hole 48, and is blown up into the air blowing space 41 on the top surface 40 of the substrate case cover 39.
[0054]
A part of the wind collides with the second air blowing guide wall 47, passes through the second through hole 46, and is blown up into the air blowing space 41 on the upper surface of the substrate case cover 39. Finally, it hits the first air blowing guide wall 45, blows up through the first through hole 44, reaches the substrate case cover 39, and reaches the ventilation hole 42 of the second heating coil 23.
[0055]
Here, a part of the wind is blocked by the temperature detection unit 43 and diffused radially around the ventilation hole 41 on the lower surface of the second heating coil 23. The wind that has passed through the ventilation holes 42 hits the shielding plate 75 and is diffused radially on the lower surface of the shielding plate 75. This flow of wind eventually passes through the gap 59 between the presser claw 56 of the coil presser 54 and the coil 53 and reaches the wall 55 of the coil presser 54 while cooling the coil 53. The wind that has reached the wall 55 passes between the first ring 71 and the second ring 72, passes through the outer peripheral recess 69 between the outer peripheral protrusions 67, and passes through the air holes 70 in the ten walls 55. The second heating coil 23 is dissipated outward. When passing through the ventilation hole 42, the wind from the sirocco fan 34 strikes the first air blowing guide wall 45 and tends to flow strongly downwind.
[0056]
However, since the temperature detection unit 43 is provided on the leeward side of the ventilation hole 42, a part of the wind hitting the temperature detection unit 43 flows to the lower surface of the second heating coil 23 and passes through the ventilation hole 42. The wind flowing on the upper surface of the second heating coil 23 is weakened by the temperature detection unit 43 located leeward of the ventilation hole 42, and the wind hitting the temperature detection unit 43 bounces up to the windward side and passes through the ventilation hole 42. At that time, the flow of wind is radiated radially over the upper surface of the second heating coil 23 with uniform strength. Therefore, the radially uniform air flows through the gap 59 smoothly from the air vent hole 42 to the air hole 70 without any obstacles, so that the coil 53 can be cooled efficiently. Since the windproof member 60 below the temperature detector 43 has an inverted conical shape, the pressure loss can be reduced and reduced when the cooling air is separated into the upper surface and the lower surface of the second heating coil 23.
[0057]
On the lower surface of the second heating coil 23, the wind that blows up from the third through hole 48, the second through hole 46, and the first through hole 44 and does not pass through the ventilation hole 42 flows under the second heating coil 23. It is dissipated radially and dissipates outward of the second heating coil 23 while cooling the lower surface of the coil 53. At this time, the cooling air flowing through the lower surface of the second heating coil 23 as a whole is merged with the wind that has passed through the second through hole 46 and the third through hole 48 and the wind that has passed through the first through hole 44 is radial. Thus, the second heating coil 23 can be efficiently cooled.
[0058]
When the pan 87 is made of a magnetic metal, for example, if it is an enamel pan or the like, the control circuit 20 determines a load current and supplies an alternating current of 20 kHz to the second heating coil 23. Since almost no eddy current is generated in the shield plate 81 in a magnetic field of 20 kHz, heat generation of the shield plate 81 is not a problem.
[0059]
As described above, according to the present embodiment, the first through hole 44 of the substrate case cover 39 is provided below the ventilation hole 42, the temperature detection unit 43 is provided in the ventilation hole 42, and the shielding plate 75, the coil 53, By providing the gap 59 between the two, it is possible to efficiently cool the upper surface of the second heating coil 23 with uniform radial cooling air from the ventilation hole 42 which is the center of the second heating coil 23, and By providing the second through hole 46 and the third through hole 48, the lower surface of the second heating coil 23 can be uniformly cooled radially from the center of the second heating coil 23. Both the upper surface and the lower surface of the heating coil 23 can be cooled simultaneously and radially.
[0060]
(Example 2)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. In FIG. 7, the flat plate 13, the second heating coil 23, the upper substrate 27, the upper substrate case 28, the upper heat sink 36, the air blowing space 41, the substrate case cover 39, the top surface 40, the ventilation holes 42, the temperature detection unit 43, First through hole 44, first air blowing guide wall 45, second through hole 46, second air blowing guide wall 47, third through hole 48, third air blowing guide wall 49, ferrite 50, base 51, coil 53, coil retainer 54, wall 55, retainer claw 56, protrusion 57, extension portion 58, gap 59, windproof member 60, concave housing portion 61, temperature detection table 62, temperature detection element 63, temperature detection unit 64 , Holding spring 65, space 66, outer peripheral convex portion 67, inner peripheral convex portion 68, outer peripheral concave portion 69, air hole 70, first ring 71, second ring 72, outer peripheral groove portion 73, mounting rib 74, conductive coating film 78. , Electrode 79, transparent Grayed 83, is the same function and shape as in Example 1, using the same reference numerals.
[0061]
1 differs from the configuration of FIG. 1 in that a plurality of contact projections 91 having a height of 2 mm are provided on the upper surface of the shield plate 90 which is a non-magnetic metal plate, and the fitting hole 93 of the shield plate 92 is more than the ventilation hole 42. It is a point opened in a large area. Since the protrusion 91 is provided, the shield plate 90 and the flat plate 13 are not in close contact with each other, and a gap 94 of about 2 mm is generated between the shield plate 90 and the flat plate 13.
[0062]
Further, by increasing the size of the fitting hole 93, the wind blown from the ventilation hole 42 can pass through the fitting hole 93 and reach the shield plate 90.
[0063]
The operation of the induction heating apparatus configured as described above will be described below. First, it is the same as in the first embodiment until the wind from the sirocco fan 34 passes through the ventilation hole 42. Further, the movement of the wind diffused on the lower surface of the second heating coil 23 is the same as that of the first embodiment.
[0064]
Regarding the wind that has passed through the ventilation holes 42, the wind that has passed through the fitting holes 93 collides with the temperature detector 43, and a part of the wind is diffused radially while cooling the upper surface of the coil 53 along the lower surface of the shielding plate 92. The wind that has passed through the fitting hole 93 passes through the center of the shield plate 90 and collides with the flat plate 13, and the gap 94 between the shield plate 90 and the flat plate 13 radially extends along the lower surface of the flat plate 13. To be dissipated. At this time, the shield plate 90 and the lower surface of the flat plate 13 are cooled and diffused radially.
[0065]
As described above, the shield plate 90 and the flat plate 13 can be cooled by allowing the air passing through the ventilation holes 42 to pass through the gap 94 provided between the shield plate 90 and the flat plate 13.
[0066]
In the first embodiment, the coil 53 of the second heating coil 23 has two layers. However, in order to increase the number of turns, three or four layers may be used. In the second embodiment, the gap 94 is provided between the flat plate 13 and the shield plate 90, but the gap 94 may be provided between the shield plate 90 and the shield plate 92, or the shield plate 92. Needless to say, a gap 94 may be provided between the coil holder 54 and the coil retainer 54.
[0067]
【The invention's effect】
As described above, according to the present invention, it is possible to realize an excellent induction heating apparatus capable of efficiently cooling the lower surface and the upper surface of the heating coil from the center with uniform radial cooling air.
[Brief description of the drawings]
FIG. 1 is a partial sectional view of a second heating coil in Embodiment 1 of the present invention.
FIG. 2 is an exploded perspective view of the induction heating device in Embodiment 1 of the present invention.
FIG. 3 is a perspective view of a control unit of the induction heating apparatus in Embodiment 1 of the present invention.
FIG. 4 is a plan view of the induction heating apparatus in Embodiment 1 of the present invention.
FIG. 5 is a partial perspective view of a second heating coil in Embodiment 1 of the present invention.
FIG. 6 is a partial perspective view of a second heating coil in Embodiment 1 of the present invention.
FIG. 7 is a partial cross-sectional view of a second heating coil in Embodiment 2 of the present invention.
[Explanation of symbols]
13 Flat plate
23 Second heating coil (heating coil)
34 Sirocco fan (blower)
42 Ventilation holes
43 Temperature detector
45 1st ventilation guide wall
47 Second air blowing guide wall
49 3rd ventilation guide wall
50 Ferrite
51 base
53 coils
54 Coil retainer
55 Wall
56 Pressing claw
58 Extension part (holding claw body)
59 Clearance
60 Windproof members
67 Perimeter convex
70 wind hole
71 First ring (ring-shaped conductor)
72 Second ring (ring-shaped conductor)
75 Shield plate
81 Shield plate (non-magnetic metal plate)
90 Shield plate (Non-magnetic metal plate)
92 Shield plate
94 Clearance

Claims

A flat plate for placing an object to be heated, located in the plane plate downward, and a heating coil for chromatic ventilation hole in the middle with a substantially donut shape, and a gap provided between the flat plate and the heating coil, A blowing device, and a blowing guide wall that is located below the heating coil and that induces a part of the cooling air generated by the blowing device and guides the cooling air upward from a substantially central lower portion of the heating coil. the Kihiya却風before induced in the previous SL blast guide wall in the Tsufuana, the downward as evenly flow radially from the center of the ventilation holes in the lower surface and the gap of the heating coil Shin設 An induction heating apparatus in which a temperature detection unit having a windproof member is formed in the ventilation hole .

A flat plate for placing an object to be heated, located in the plane plate downward, and a heating coil for chromatic ventilation hole in the middle with a substantially donut shape, and a gap provided between the flat plate and the heating coil, blower An apparatus, and a ventilation guide wall that guides a part of cooling air generated by the blower located below the heating coil and guides the cooling wind upward from a substantially central lower part of the heating coil , the Kihiya却風before induced in the Tsufuana before Symbol blast guide wall, to flow evenly into radially from the center of the ventilation hole and the gap between the lower surface of the heating coil, from the center of the ventilation hole An induction heating device that is eccentric and has a temperature detector.

A planar plate for placing an object to be heated; a heating coil located below the planar plate; a gap provided between the planar plate and the heating coil; a blower; and the heating coil located below the heating coil. A blowing guide wall for guiding a part of the cooling air generated by the blower to guide the cooling air upward from substantially lower center of the heating coil, and the heating coil is substantially donut-shaped and has a ventilation hole at the center. An induction heating apparatus configured to pass a part of the cooling air through the gap between the flat plate and the heating coil,
The heating coil is a base, a coil, a ferrite arranged radially from the center of the coil, and a coil retainer, said coil retainer was Shin設said coil upper surface from the coil outer peripheral covering wall and the wall An induction heating apparatus comprising a plurality of pressing nails and having a structure in which an air hole is provided in the wall.

A planar plate for placing an object to be heated; a heating coil located below the planar plate; a gap provided between the planar plate and the heating coil; a blower; and the heating coil located below the heating coil. A blowing guide wall for guiding a part of the cooling air generated by the blower to guide the cooling air upward from substantially lower center of the heating coil, and the heating coil is substantially donut-shaped and has a ventilation hole at the center. An induction heating apparatus configured to pass a part of the cooling air through the gap between the flat plate and the heating coil,
The heating coil includes a base, a coil, a U-shaped ferrite opened radially from the center of the coil, and a coil presser.
The coil presser is provided on the outer periphery of the heating coil and includes a wall that covers the outer periphery of the U-shaped ferrite arrangement, and a plurality of presser claws extending from the wall to the upper surface of the coil,
The U-shaped ferrite inner circumferential convex portion is located on the inner side of the coil inner circumference, and the outer circumferential convex portion is located on the outer side of the coil outer circumference,
The coil retainer wall has an air hole, said air hole is an induction heating device provided between the outer convex section of one said U-shaped ferrite and other of said U-shaped outer convex portion of the ferrite.

The induction heating device according to claim 3 or 4, wherein two ring-shaped conductors are separated in the vertical direction on the outer periphery of the heating coil and arranged substantially in parallel, and an air hole is located between the upper and lower ring-shaped conductors.

Wherein the shield plate between the heating coil top and said flat plate is disposed, the shield plate may thwart the course from the ventilation hole to the shielding plate above the cooling air induced in a coil upper surface of the heating coil, wherein induction heating apparatus according to claim 1 or 2 has a structure to diffuse into the heating coil periphery through between the cooling air and the coil top and said shield plate.

The coil retainer has a plurality of retaining claws that run from the wall toward the center, and a downward projecting protrusion that extends near the tip of the retaining claws. The induction heating device according to claim 3 or 4, wherein the induction heating device is configured.

A shielding plate is arranged between the upper part of the heating coil and the flat plate, a nonmagnetic metal plate is arranged between the shielding plate and the flat plate, and between the heating coil and the shielding plate or between the shielding plate and the nonmagnetic metal plate. A gap is provided in at least one of the gap between the non-magnetic metal plate and the flat plate to prevent the cooling air guided from the ventilation hole to the upper surface of the heating coil from moving upward to the shielding plate. the induction heating apparatus according to claim 5, wherein the cooling air is configured to diffuse the heating coil outer periphery through the gap.

The control circuit for driving the heating coil is formed by an inverter circuit, and the inverter circuit is capable of heating a nonmagnetic metal having high conductivity and low resistance such as aluminum and copper. Induction heating device.