JP4072721B2 - Artificial heart pump - Google Patents

Artificial heart pump Download PDF

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Publication number
JP4072721B2
JP4072721B2 JP2003034927A JP2003034927A JP4072721B2 JP 4072721 B2 JP4072721 B2 JP 4072721B2 JP 2003034927 A JP2003034927 A JP 2003034927A JP 2003034927 A JP2003034927 A JP 2003034927A JP 4072721 B2 JP4072721 B2 JP 4072721B2
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dynamic pressure
pressure generating
generating groove
plate portion
thrust dynamic
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JP2004245303A (en
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岳志 佐野
俊幸 長田
剛 大久保
雅士 田川
隆志 山根
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Mitsubishi Heavy Industries Ltd
National Institute of Advanced Industrial Science and Technology AIST
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Mitsubishi Heavy Industries Ltd
National Institute of Advanced Industrial Science and Technology AIST
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/04—Shafts or bearings, or assemblies thereof
    • F04D29/046—Bearings
    • F04D29/047—Bearings hydrostatic; hydrodynamic
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/04—Shafts or bearings, or assemblies thereof
    • F04D29/041—Axial thrust balancing
    • F04D29/0413—Axial thrust balancing hydrostatic; hydrodynamic thrust bearings

Description

【０００１】
【発明の属する技術分野】
本発明は、生体の心臓の代替又は補助として血液を取り込むとともに圧送する遠心方式の人工心臓ポンプに関する。
【０００２】
【従来の技術】
一般に、遠心方式の人工心臓ポンプは、図８に示すように、大きくは、ハウジング１と、このハウジング１内に固定された軸受２と、この軸受２に対しハウジング１内で回転可能に支持された羽根車３と、を備えており、羽根車３の回転により、軸方向前方から血液を取り込んで径方向外方へ圧送するようになっている（例えば、特許文献１参照）。
【０００３】
具体的には、ハウジング１は、前側ハウジング１０と後側ハウジング１１とを組み合わせてなり、溶接や接着剤やボルト等による接合により一体化されて、内部空間が形成されたものである。前側ハウジング１０の前端には、外部からハウジング１内に血液を取り込むための吸入側接続口１２が、詳細は後述する軸受２の軸線上に設けられ、他方、前側ハウジング１０又は後側ハウジング１１（図８では前側ハウジング１０）の一側には、ハウジング１内から外部に血液を送り出すための吐出側接続口１３が設けられている。つまり、羽根車３の回転により、吸入側接続口１２から血液が吸引されてハウジング１内に取り込まれ、その血液が詳細は後述する羽根車３の前側シュラウド３２と後側シュラウド３１との間隙Ｐ（以下、「羽根車内流路」と記すことがある）を経て昇圧され、吐出側接続口１３から送り出されるという主たる血液流路が形成される。
【０００４】
軸受２は、詳細は後述する羽根車３のラジアル移動を規制するための管状の軸部２０と、この軸部２０の前後端からそれぞれ径方向外方に突出するよう配設され、羽根車３のスラスト移動を規制するための円盤状の前側プレート部２１、後側プレート部２２と、前側プレート部２１の外面すなわち前面を覆い、吸入側接続口１２から取り込まれた軸方向後方に向けて流れる血液を詳細は後述する羽根車内流路Ｐの入口Ｐ1に送り込むために中心部が隆起した曲面を有する先端部２３と、この先端部２３から前側プレート部２１、軸部２０、後側プレート部２２、及び後側ハウジング１１の後端を貫通する軸支部２４と、よりなり、これらは溶接や接着剤やボルト等によってハウジング１内でこれと一体的に固定されている。
【０００５】
羽根車３は、軸部２０の外周面に微小間隙を隔てて対向する貫通孔である内周面とともに前側プレート部２１、後側プレート部２２の各内面に微小間隙を隔てて対向する前面、後面を有するセラミック焼結体のスリーブ３０と、このスリーブが同軸状に挿嵌された後側シュラウド３１と、この後側シュラウド３１の前方でこれと同軸状で所定の間隙を隔てた前側シュラウド３２と、この前側シュラウド３２と後側シュラウド３１との間隙に設けられ、血液を吸入するとともに昇圧するための複数の羽根３３と、よりなり、これらは一体成型、焼嵌めやロウ付けや接着剤等による接合により一体的になっている。つまり、羽根車３（スリーブ３０）は、ハウジング１と一体の軸受２（軸部２０、前側プレート部２１及び後側プレート部２２）に対して回転可能になり、この羽根車３の回転に伴って、軸方向前方から血液を取り込み、羽根車内流路Ｐとなる前側シュラウド３２と後側シュラウド３１との間隙で羽根３３により昇圧しながら、径方向外方へ圧送するという人工心臓ポンプに望まれる機能が得られる。
【０００６】
なお、羽根車３の回転駆動は、例えば磁力を活用してなされる。具体的には、図８に示すように、後側シュラウド３１の後部には、形成された環状溝３１ｃに永久磁石３４が収容されてこれが蓋体３５で密閉されて固定され、他方、後側ハウジング１１の後部には、永久磁石３４の周囲を覆う同軸状の位置に、外部又は内蔵の電源に接続された回転磁界発生器１４が配設されている。これにより、電源から電力供給を受けた回転磁界発生器１４が回転磁界を発生し、この磁力を受けて永久磁石３４が同期してその軸線周りに回転しようとすることで、羽根車３が軸受２に対して回転するわけである。
【０００７】
ここで、軸受２に対して羽根車３を円滑に回転させる潤滑機構について、図９〜図１４を参照しながら述べる。図９に示すように、羽根車３の回転に伴って、羽根車内流路Ｐには径方向内方にある入口Ｐ1から径方向外方にある出口Ｐ2に向けて血液が流れるが、その血液は羽根３３により遠心力の作用とあいまって昇圧される。従って、血液に作用する圧力は、入口Ｐ1よりも出口Ｐ2の方が高くなり、入口Ｐ1と出口Ｐ2の間で圧力差が生じる。
【０００８】
このため、羽根車内流路Ｐにおける出口Ｐ2から噴き出された血液の一部は、後側ハウジング１１の内壁と後側シュラウド３１の外壁との間隙に導き入れられ、続いて後側プレート部２２の内面とスリーブ３０の後面との微小間隙Ｑ1、軸部２０の外周面とスリーブ３０の内周面との微小間隙Ｑ2、及び前側プレート部２１の内面とスリーブ３０の前面との微小間隙Ｑ3を経由して、羽根車内流路Ｐにおける入口Ｐ1に送り出され、結局、吸入側接続口１２からハウジング１内に取り込まれた血液に合流するようになる（図９中の点線矢印参照）。つまり、羽根車３の回転中は、羽根車３（スリーブ３０）と軸受２（軸部２０、前側プレート部２１及び後側プレート部２２）との微小間隙Ｑ1〜Ｑ3に血液が流動することになり、この血液を潤滑流体として活用するわけである。
【０００９】
但し、回転中の羽根車３には、径方向のラジアル荷重及び軸方向のスラスト荷重が作用するため、これらを支持して微小間隙Ｑ1〜Ｑ3を確保すべく以下の工夫がなされている。
【００１０】
先ず第１に、軸受２を構成する軸部２０の外周面には、図９〜図１１に示すように、羽根車３（スリーブ３０）のラジアル荷重を支持するためのラジアル動圧発生溝１４０（図１０中のシングルハッチング部参照）が部分的に複数設けられている。これらラジアル動圧発生溝１４０は、スパイラルグルーブと呼ばれる螺旋状をなしており、一律に深さがほぼ一定に加工されたものである。
【００１１】
第２に、前側プレート部２１の内面には、図９、及び図１２〜図１４に示すように、羽根車３のスラスト荷重を支持するための前側スラスト動圧発生溝１４１が複数設けられている。これら前側スラスト動圧発生溝１４１は、渦巻状をなしており、ラジアル動圧発生溝１４０と同様、一律に深さがほぼ一定に加工されたものである。他方、後側プレート部２２の内面にも、これと同様に、羽根車３のスラスト荷重を支持するための後側スラスト動圧発生溝１４２が複数設けられている。なお、図１２は、前側スラスト動圧発生溝１４１又は後側スラスト動圧発生溝１４２が、前側プレート部２１又は後側プレート部２２における各内面上で部分的に設けられた態様を示し、図１３は、前側プレート部２１又は後側プレート部２２における各内面上の外周すなわち外縁から、内周すなわち軸部２０の外周面に至る間に連続するよう設けられた態様を示している。
【００１２】
このような工夫を施すことにより、回転中の羽根車３は、ラジアル動圧発生溝１４０、前側スラスト動圧発生溝１４１又は後側スラスト動圧発生溝１４２を流動する血液にラジアル動圧及びスラスト動圧が生じて、軸受２に対して浮上した非接触状態に保持されるようになるため、円滑な回転が可能となり、ひいては人工心臓ポンプとしての血液供給の安定性と耐久性の向上につながる。
【００１３】
【特許文献１】
特開平７−１３６２４７号公報（第２−３頁、第１図）
【００１４】
【発明が解決しようとする課題】
ところで、人工心臓ポンプには、取り扱う対象流体が血液であってしかも用いられる対象が人間や動物であることから、特に、溶血及び血栓を長期間引き起こさないことが宿命的な解決課題として強く要求される。なお、溶血とは、血液中の赤血球の表面膜が損傷してその機能が失われる現象であり、血栓とは、血液が凝集して血管等の血液流路を塞ぐ現象である。
【００１５】
しかし、上記の人工心臓ポンプでは、羽根車３をなすスリーブ３０と、軸受２をなす軸部２０、前側プレート部２１及び後側プレート部２２と、で形成される微小間隙Ｑ1〜Ｑ3において、溶血及び血栓が頻発していた。何故ならば、この微小間隙Ｑ1〜Ｑ3は、従来、数μｍ〜十数μｍと極めて狭い間隙寸法が設定されていたため、血液そのものが流動し難い状況にあり、溶血に関していえば、軸受２に対する羽根車３の相対的な回転速度差により、流動する血液に多大なせん断応力が作用し、このせん断応力で赤血球が損傷してしまうからである。また、血栓に関しては、流動する血液が接触する個所における素材の面粗度や親和性の影響は勿論であるが、血液そのものの流動速度が遅かったり、流動量が少なかったりして滞る場合に発生すると考えられ、そうすると、微小間隙Ｑ1〜Ｑ3が極めて狭いことは不利な要素であったからである。
【００１６】
このような溶血及び血栓の問題を解決する手法としては、微小間隙Ｑ1〜Ｑ3の間隙寸法を単に拡大することが考えられる。しかし、拡大しすぎると今度は、回転中の羽根車３のラジアル荷重及びスラスト荷重を支持するためのラジアル動圧及びスラスト動圧の効力が著しく低減し、これにより、人工心臓ポンプとしての血液供給の安定性と耐久性につながる軸受２に対する歯車３の円滑な回転が阻害されるため、その間隙寸法は３０μｍ〜４０μｍ程度が限界であり、実際にこれでは溶血及び血栓の問題を十分に解決できなかった。
【００１７】
そこで、本発明は、上記の問題に鑑みてなされたものであり、血液供給の安定性と耐久性を維持しつつ、溶血及び血栓の発生を抑制できる人工心臓ポンプを提供することを目的とするものである。
【００１８】
上記目的を達成するため、本発明による人工心臓ポンプは、ハウジングと、このハウジング内に固定され、軸部及びこの軸部から径方向外方に突出する前側プレート部、後側プレート部よりなる軸受と、前記軸部の外周面に微小間隙を隔てて対向する貫通孔とともに、前記前側プレート部、後側プレート部の各内面に微小間隙を隔てて対向する前面、後面を有し、前記軸受に対し前記ハウジング内で回転可能に支持された羽根車と、を備えていて、前記羽根車の回転により、軸方向前方から血液を取り込んで径方向外方へ圧送するとともに、この圧送された血液の一部を前記後側プレート部の内面と前記羽根車の後面との微小間隙に導き入れ、前記軸部の外周面と前記羽根車の貫通孔との微小間隙、及び前記前側プレート部の内面と前記羽根車の前面との微小間隙を経由して、取り込まれる前記血液に合流させる人工心臓ポンプにおいて、前記軸部の外周面には前記羽根車のラジアル荷重を支持するためのラジアル動圧を発生するラジアル動圧発生溝が複数設けられ、前記前側プレート部、後側プレート部の各内面には前記羽根車のスラスト荷重を支持するためのスラスト動圧を発生する前側スラスト動圧発生溝、後側スラスト動圧発生溝が複数ずつ設けられており、前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び後側スラスト動圧発生溝のうちそれぞれの少なくとも１つが、他の前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝よりも深さが深く血液の流動量が多いとともに、他の前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝よりも発生する前記ラジアル動圧及び前記スラスト動圧が低いことを特徴とする。
【００１９】
これにより、深さの深いラジアル動圧発生溝、前側スラスト動圧発生溝及び後側スラスト動圧発生溝で血液を多く許容できるため、圧送された血液の一部が潤滑流体として流動する後側プレート部の内面と羽根車の後面との微小間隙、軸部の外周面と羽根車の貫通孔との微小間隙、及び前側プレート部の内面と羽根車の前面との微小間隙では、その血液そのものの流動量が増し、溶血及び血栓の発生が抑制される。しかも、他のラジアル動圧発生溝、前側スラスト動圧発生溝及び後側スラスト動圧発生溝では、流動する血液にラジアル動圧及びスラスト動圧が有効に生じるため、軸受に対する羽根車の円滑な回転が可能となり、人工心臓ポンプとしての血液供給の安定性と耐久性が維持される。
【００２０】
ここで、実用性を踏まえると、深さの深い前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝は、他の前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝よりも１０倍以上深さが深いことが好ましい。
【００２１】
また、溶血及び血栓の発生をより効果的に抑制すべく、血液そのものの流動量をより増す観点から、深さの深い前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝は、他の前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝よりも幅が広いことが好ましい。
【００２２】
更に、有効なラジアル動圧及びスラスト動圧の発生を確保するとともに、血液そのものの流動を容易にする目的で、前記ラジアル動圧発生溝が螺旋状で、前記前側スラスト動圧発生溝及び前記後側スラスト動圧発生溝が渦巻状であって、深さの深い前記ラジアル動圧発生溝が、前記軸部における前記後側プレート部の内面から前記前側プレート部の内面に至る間に連続し、深さの深い前記前側スラスト動圧発生溝及び前記後側スラスト動圧発生溝が、前記前側プレート部及び前記後側プレート部それぞれにおける外縁から前記軸部の外周面に至る間に連続しているとよい。
【００２３】
【発明の実施の形態】
本発明者らは、人工心臓ポンプの宿命的な解決課題である羽根車と軸受との微小間隙における溶血及び血栓の抑制に関して、人工心臓ポンプとしての血液供給の安定性と耐久性を維持することを基本前提に鋭意検討を重ね、その結果、上記の微小間隙において羽根車を浮上状態で回転可能に支持するための軸受に形成されている各種動圧発生溝の態様に着眼し、本発明をなすに至った。
【００２４】
つまり、本発明の人工心臓ポンプの大きな特徴は、軸受をなす軸部、前側プレート部及び後側プレート部に複数ずつ形成されているラジアル動圧発生溝、前側スラスト動圧発生溝及び後側動圧発生溝が、それぞれ深さの浅いものと深さの深いものとからなっており、深さの浅いものは、人工心臓ポンプとしての血液供給の安定性と耐久性を維持すべく、流動する血液に有効な動圧を生じさせて軸受に対する羽根車の円滑な回転を確保する役割を果たし、他方の深いものは、溶血及び血栓の発生を抑止すべく、血液そのものの流動量を確保する役割を果たす。
【００２５】
以下に、本発明の人工心臓ポンプの実施形態について図面を参照しながら詳述する。先ず、本発明の第１実施形態について説明する。図１は第１実施形態の人工心臓ポンプの潤滑機構を説明する模式図、図２はその人工心臓ポンプにおける軸受のラジアル動圧発生溝を示す軸部外周面の展開図、図３は図２におけるラジアル動圧発生溝と直交する断面を示す軸部外周面の横断面図、図４はその人工心臓ポンプにおける軸受のスラスト動圧発生溝を示す前側プレート部（又は後側プレート部）内面の平面図、図５は図４におけるスラスト動圧発生溝と直交する断面を示す前側プレート部内面の円周方向断面図である。なお、図中で図８及び図９と同じ名称で同じ機能を果たす部分には同一の符号を付し、重複する説明はここでは省略し、相違する点について説明する。後述する第２実施形態においても同様とする。
【００２６】
本第１実施形態では、先ず、図１〜図３に示すように、軸受２を構成する軸部２０の外周面には、羽根車３（スリーブ３０）のラジアル荷重を支持するためのラジアル動圧発生溝４０が部分的に複数（図２では６本図示）設けられている。これらラジアル動圧発生溝４０は、スパイラルグルーブと呼ばれる螺旋状をなしており、個々において深さがほぼ一定に加工されたものである。
【００２７】
ここで、ラジアル動圧発生溝４０は、対称位置に配置された一対の第１のラジアル動圧発生溝４０ａ（図２中のダブルハッチング部参照）と、これらの間に配置された第２のラジアル動圧発生溝４０ｂ（図２中のシングルハッチング部参照）とからなり、第１のラジアル動圧発生溝４０ａの深さｓａは、第２のラジアル動圧発生溝４０ｂの深さｓｂよりも深く形成されている。例えば、第１のラジアル動圧発生溝４０ａの深さｓａは５００μｍ〜６００μｍ程度であり、他方、第２のラジアル動圧発生溝４０ｂの深さｓｂは数十μｍ程度である。
【００２８】
また、図１、図４及び図５に示すように、前側プレート部２１の内面には、羽根車３のスラスト荷重を支持するための前側スラスト動圧発生溝４１が部分的に複数（図４では６本図示）設けられている。これら前側スラスト動圧発生溝４１は、渦巻状をなしており、ラジアル動圧発生溝４０と同様、個々において深さがほぼ一定に加工されたものである。
【００２９】
ここで、前側スラスト動圧発生溝４１は、対称位置に配置された一対の第１の前側スラスト動圧発生溝４１ａ（図４中のダブルハッチング部参照）と、これらの間に配置された第２の前側スラスト動圧発生溝４１ｂ（図４中のシングルハッチング部参照）とからなり、第１の前側スラスト動圧発生溝４１ａの深さｔａは、第２の前側スラスト動圧発生溝４１ｂの深さｔｂよりも深く形成されている。例えば、第１の前側スラスト動圧発生溝４１ａの深さｔａは、第１のラジアル動圧発生溝４０ａの深さｓａと同様、５００μｍ〜６００μｍ程度であり、他方、第２の前側スラスト動圧発生溝４１ｂの深さｓｂは、第２のラジアル動圧発生溝４０ｂの深さｓｂと同様、数十μｍ程度である。
【００３０】
更に、後側プレート部２２の内面にも、これと同様の態様で、羽根車３のスラスト荷重を支持するための後側スラスト動圧発生溝４２が複数設けられており、これら後側スラスト動圧発生溝４２は、深さの深い第１の前側スラスト動圧発生溝４２ａと、深さの浅い第２の前側スラスト動圧発生溝４１ｂとからなる。
【００３１】
このように各種動圧発生溝を構成することにより、深さの深い動圧発生溝である第１のラジアル動圧発生溝４０ａ、第１の前側スラスト動圧発生溝４１ａ及び第１の後側スラスト動圧発生溝４２ａで血液を多く許容できるため、圧送された血液の一部が潤滑流体として流動する、羽根車３をなすスリーブ３０と、軸受２をなす軸部２０、前側プレート部２１及び後側プレート部２２と、で形成される微小間隙Ｑ1〜Ｑ3においては、その血液そのものの流動量が増し、溶血及び血栓の発生が抑制されることになる。しかも、深さの浅い動圧発生溝である第２のラジアル動圧発生溝４０ｂ、第２の前側スラスト動圧発生溝４１ｂ及び第２の後側スラスト動圧発生溝４２ｂでは、流動する血液にラジアル動圧及びスラスト動圧が有効に生じるため、軸受２に対する羽根車３の円滑な回転が可能となり、人工心臓ポンプとしての血液供給の安定性と耐久性が維持されることになる。
【００３２】
なお、溶血及び血栓の発生が抑制できる血液そのものの実用的な流動量を確保するためには、第１のラジアル動圧発生溝４０ａ、第１の前側スラスト動圧発生溝４１ａ及び第１の後側スラスト動圧発生溝４２ａの深さｓａ、ｔａが、第２のラジアル動圧発生溝４０ｂ、第２の前側スラスト動圧発生溝４１ｂ及び第２の後側スラスト動圧発生溝４２ｂの深さｓｂ、ｔｂよりも１０倍以上深いことが好ましい。
【００３３】
また、溶血及び血栓の発生をより効果的に抑制すべく、血液そのものの流動量をより増す観点から、図３及び図５に示す第１のラジアル動圧発生溝４０ａ、第１の前側スラスト動圧発生溝４１ａ及び第１の後側スラスト動圧発生溝４２ａの幅ｕａ、ｖａが、第２のラジアル動圧発生溝４０ｂ、第２の前側スラスト動圧発生溝４１ｂ及び第２の後側スラスト動圧発生溝４２ｂの幅ｕｂ、ｖｂよりも広いことが好ましい。
【００３４】
次に、本発明の第２実施形態について図６及び図７を参照しながら説明する。図６は第２実施形態の人工心臓ポンプにおける軸受のラジアル動圧発生溝を示す軸部外周面の展開図、図７はその人工心臓ポンプにおける軸受のスラスト動圧発生溝を示す前側プレート部（又は後側プレート部）内面の平面図である。本第２実施形態の特徴は、第１実施形態における第１のラジアル動圧発生溝４０ａ、第１の前側スラスト動圧発生溝４１ａ及び第１の後側スラスト動圧発生溝４２ａを変形し、血液そのものの流動を容易にした点にある。
【００３５】
つまり、第１のラジアル動圧発生溝４０ａは、図６に示すように、軸部２０における前後端、すなわち後側プレート部２２の内面から前側プレート部２１の内面に至る間に連続するよう形成されている。また、第１の前側スラスト動圧発生溝４１ａは、図７に示すように、前側プレート部２１における外縁から軸部２０の外周面に至る間に連続するよう形成されている。更に、第１の後側スラスト動圧発生溝４２ａも、これと同様の態様で、後側プレート部２２における外縁から軸部２０の外周面に至る間に連続するよう形成されている。従って、血液そのものは、これら第１のラジアル動圧発生溝４０ａ、第１の前側スラスト動圧発生溝４１ａ及び第１の後側スラスト動圧発生溝４２ａに沿って、連続的に容易に流動することが可能となり、より効果的に溶血及び血栓を抑止できる。
【００３６】
ちなみに、第２のラジアル動圧発生溝４０ｂは、軸部２０における前後端まで至っておらず、第２の前側スラスト動圧発生溝４１ｂ及び第２の後側スラスト動圧発生溝４２ｂは、前側プレート部２１及び後側プレート部２２それぞれにおける外縁まで至っていないが、有効なラジアル動圧及びスラスト動圧の発生には支障はない。
【００３７】
その他本発明は上記の各実施形態に限定されず、本発明の趣旨を逸脱しない範囲で、種々の変更が可能である。例えば、第２のラジアル動圧発生溝４０ｂが、軸部２０における前後端まで連続するよう形成され、第２の前側スラスト動圧発生溝４１ｂ及び第２の後側スラスト動圧発生溝４２ｂが、前側プレート部２１及び後側プレート部２２それぞれにおける外縁から軸部２０の外周面に至る間に連続するよう形成されても、勿論構わない。また、前側スラスト動圧発生溝４１及び後側スラスト動圧発生溝４２は、上記したような渦巻状に限らず、例えば放射状であってもよい。
【００３８】
【発明の効果】
以上説明した通り、本発明の人工心臓ポンプによれば、ハウジングと、このハウジング内に固定され、軸部及びこの軸部から径方向外方に突出する前側プレート部、後側プレート部よりなる軸受と、前記軸部の外周面に微小間隙を隔てて対向する貫通孔とともに、前記前側プレート部、後側プレート部の各内面に微小間隙を隔てて対向する前面、後面を有し、前記軸受に対し前記ハウジング内で回転可能に支持された羽根車と、を備えていて、前記羽根車の回転により、軸方向前方から血液を取り込んで径方向外方へ圧送するとともに、この圧送された血液の一部を前記後側プレート部の内面と前記羽根車の後面との微小間隙に導き入れ、前記軸部の外周面と前記羽根車の貫通孔との微小間隙、及び前記前側プレート部の内面と前記羽根車の前面との微小間隙を経由して、取り込まれる前記血液に合流させる人工心臓ポンプにおいて、前記軸部の外周面には前記羽根車のラジアル荷重を支持するためのラジアル動圧発生溝が複数設けられ、前記前側プレート部、後側プレート部の各内面には前記羽根車のスラスト荷重を支持するための前側スラスト動圧発生溝、後側スラスト動圧発生溝が複数ずつ設けられており、前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び後側スラスト動圧発生溝のうちそれぞれの少なくとも１つが、他の前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝よりも深さが深くなっている。つまり、深さの深いラジアル動圧発生溝、前側スラスト動圧発生溝及び後側スラスト動圧発生溝で血液を多く許容できるため、圧送された血液の一部が潤滑流体として流動する羽根車と軸受とで形成される各微小間隙では、その血液そのものの流動量が増し、これにより溶血及び血栓の発生が抑制できる。しかも、他のラジアル動圧発生溝、前側スラスト動圧発生溝及び後側スラスト動圧発生溝では、流動する血液にラジアル動圧及びスラスト動圧が有効に生じるため、軸受に対する羽根車の円滑な回転が可能となり、その結果人工心臓ポンプとしての血液供給の安定性と耐久性が維持できる。
【００３９】
ここで、深さの深い前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝が、他の前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝よりも１０倍以上深さが深いと、溶血及び血栓の発生が抑制できる血液そのものの実用的な流動量を十分確保することが可能となる。
【００４０】
また、深さの深い前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝が、他の前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝よりも幅が広いと、血液そのものの流動量がより増すため、溶血及び血栓の発生をより効果的に抑制することが可能となる。
【００４１】
更に、前記ラジアル動圧発生溝が螺旋状で、前記前側スラスト動圧発生溝及び前記後側スラスト動圧発生溝が渦巻状であって、深さの深い前記ラジアル動圧発生溝が、前記軸部における前記後側プレート部の内面から前記前側プレート部の内面に至る間に連続し、深さの深い前記前側スラスト動圧発生溝及び前記後側スラスト動圧発生溝が、前記前側プレート部及び前記後側プレート部それぞれにおける外縁から前記軸部の外周面に至る間に連続していると、ラジアル動圧発生溝、前側スラスト動圧発生溝及び後側スラスト動圧発生溝に特有の形態面から、有効なラジアル動圧及びスラスト動圧の発生が確保でき、その上、血液そのものの流動が容易に可能となる。
【図面の簡単な説明】
【図１】 本発明の第１実施形態である人工心臓ポンプの潤滑機構を説明する模式図である。
【図２】 第１実施形態における軸受のラジアル動圧発生溝を示す軸部外周面の展開図である。
【図３】 図２における軸部外周面の横断面図である。
【図４】 第１実施形態における軸受のスラスト動圧発生溝を示す前側プレート部内面の平面図である。
【図５】 図４における前側プレート部内面の円周方向断面図である。
【図６】 本発明の第２実施形態である人工心臓ポンプにおける軸受のラジアル動圧発生溝を示す軸部外周面の展開図である。
【図７】 第２実施形態における軸受のスラスト動圧発生溝を示す前側プレート部内面の平面図である。
【図８】 一般的な人工心臓ポンプの構成を示す要部縦断面図である。
【図９】 従来の人工心臓ポンプの潤滑機構を説明する模式図である。
【図１０】 従来の軸受のラジアル動圧発生溝を示す軸部外周面の展開図である。
【図１１】 図１０における軸部外周面の横断面図である。
【図１２】 従来の軸受のスラスト動圧発生溝を示す前側プレート部内面の平面図である。
【図１３】 従来の他の軸受のスラスト動圧発生溝を示す前側プレート部内面の平面図である。
【図１４】 図１２又は図１３における前側プレート部内面の円周方向断面図である。
【符号の説明】
１ ハウジング
２ 軸受
３ 羽根車
１０ 前側ハウジング
１１ 後側ハウジング
１２ 吸入側接続口
１３ 吐出側接続口
１４ 回転磁界発生器
２０ 軸部
２１ 前側プレート部
２２ 後側プレート部
２３ 先端部
２４ 軸支部
３０ スリーブ
３１ 後側シュラウド
３２ 前側シュラウド
３３ 羽根
３４ 永久磁石
３５ 蓋体
４０ ラジアル動圧発生溝
４０ａ 第１のラジアル動圧発生溝（深さの深い動圧発生溝４０）
４０ｂ 第２のラジアル動圧発生溝（深さの浅い動圧発生溝４０）
４１ 前側スラスト動圧発生溝
４１ａ 第１の前側スラスト動圧発生溝（深さの深い動圧発生溝４１）
４１ｂ 第２の前側スラスト動圧発生溝（深さの浅い動圧発生溝４１）
４２ 後側スラスト動圧発生溝
４２ａ 第１の後側スラスト動圧発生溝（深さの深い動圧発生溝４２）
４２ｂ 第２の後側スラスト動圧発生溝（深さの浅い動圧発生溝４２）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a centrifugal artificial heart pump that takes in blood and pumps it as an alternative or an auxiliary to a living heart.
[0002]
[Prior art]
In general, as shown in FIG. 8, a centrifugal artificial heart pump is roughly supported by a housing 1, a bearing 2 fixed in the housing 1, and a bearing 2 that is rotatable in the housing 1. An impeller 3 is provided, and blood is taken in from the front in the axial direction and pumped radially outward by rotation of the impeller 3 (see, for example, Patent Document 1).
[0003]
Specifically, the housing 1 is a combination of the front housing 10 and the rear housing 11, and is integrated by welding, bonding with an adhesive, bolts, or the like to form an internal space. At the front end of the front housing 10, a suction side connection port 12 for taking blood into the housing 1 from the outside is provided on the axis of the bearing 2, which will be described in detail later, while the front housing 10 or the rear housing 11 ( In FIG. 8, on one side of the front housing 10), there is provided a discharge side connection port 13 for sending blood out of the housing 1 to the outside. That is, by rotation of the impeller 3, blood is sucked from the suction side connection port 12 and taken into the housing 1, and the blood P is a gap P between the front shroud 32 and the rear shroud 31 of the impeller 3 described later in detail. (Hereinafter, it may be referred to as “flow path in the impeller”), the main blood flow path is formed in which the pressure is increased and sent out from the discharge side connection port 13.
[0004]
The bearing 2 is disposed so as to protrude radially outward from the front and rear ends of the shaft portion 20 to restrict radial movement of the impeller 3, which will be described in detail later, and the impeller 3. The disc-shaped front plate portion 21, the rear plate portion 22, and the outer surface of the front plate portion 21, that is, the front surface of the front plate portion 21, are flowed toward the rear in the axial direction taken in from the suction side connection port 12. The inlet P of the impeller internal flow path P to be described in detail later 1 A distal end portion 23 having a curved surface with a raised central portion so as to be fed into the shaft, and a shaft support portion penetrating from the distal end portion 23 to the front plate portion 21, the shaft portion 20, the rear plate portion 22, and the rear end of the rear housing 11. 24, and these are integrally fixed in the housing 1 by welding, an adhesive, bolts, or the like.
[0005]
The impeller 3 has a front surface facing each inner surface of the front plate part 21 and the rear plate part 22 with a minute gap together with an inner circumferential surface that is a through hole facing the outer circumferential surface of the shaft part 20 with a minute gap. A ceramic sintered body sleeve 30 having a rear surface, a rear shroud 31 into which the sleeve is coaxially fitted, and a front shroud 32 coaxially spaced from the front shroud 31 in front of the rear shroud 31. And a plurality of blades 33 that are provided in the gap between the front shroud 32 and the rear shroud 31 to inhale and pressurize blood, and these are integrally molded, shrink-fitted, brazed, adhesive, etc. It is integrated by joining. That is, the impeller 3 (sleeve 30) can rotate with respect to the bearing 2 (the shaft portion 20, the front plate portion 21, and the rear plate portion 22) integral with the housing 1, and the rotation of the impeller 3 is accompanied by rotation. Thus, an artificial heart pump that takes in blood from the front in the axial direction and pressurizes the blood radially outward while being pressurized by the blades 33 in the gap between the front shroud 32 and the rear shroud 31 that become the flow path P in the impeller is desired. Function is obtained.
[0006]
In addition, the rotational drive of the impeller 3 is made by utilizing, for example, magnetic force. Specifically, as shown in FIG. 8, a permanent magnet 34 is accommodated in an annular groove 31c formed in the rear portion of the rear shroud 31, and is sealed and fixed by a lid 35. A rotating magnetic field generator 14 connected to an external or built-in power source is disposed at the rear portion of the housing 11 at a coaxial position covering the periphery of the permanent magnet 34. As a result, the rotating magnetic field generator 14 that is supplied with power from the power source generates a rotating magnetic field, and the permanent magnet 34 receives the magnetic force and tries to rotate around its axis synchronously. It rotates with respect to 2.
[0007]
Here, a lubrication mechanism for smoothly rotating the impeller 3 with respect to the bearing 2 will be described with reference to FIGS. As shown in FIG. 9, with the rotation of the impeller 3, the impeller inner flow path P has an inlet P located radially inward. 1 Exit P radially outward from 2 The blood flows toward the head, but the blood is pressurized by the vane 33 together with the centrifugal force. Therefore, the pressure acting on the blood is the inlet P 1 Than exit P 2 Is higher, entrance P 1 And exit P 2 A pressure difference occurs between the two.
[0008]
For this reason, the outlet P in the flow path P in the impeller 2 Part of the blood ejected from the air is introduced into the gap between the inner wall of the rear housing 11 and the outer wall of the rear shroud 31, and then the minute gap between the inner surface of the rear plate portion 22 and the rear surface of the sleeve 30. Q 1 The minute gap Q between the outer peripheral surface of the shaft portion 20 and the inner peripheral surface of the sleeve 30 2 , And a minute gap Q between the inner surface of the front plate portion 21 and the front surface of the sleeve 30. Three Via the inlet P in the impeller internal flow path P 1 As a result, the blood merges with the blood taken into the housing 1 from the suction side connection port 12 (see the dotted arrow in FIG. 9). That is, during the rotation of the impeller 3, the minute gap Q between the impeller 3 (sleeve 30) and the bearing 2 (the shaft portion 20, the front plate portion 21, and the rear plate portion 22). 1 ~ Q Three Therefore, blood will flow and this blood will be used as a lubricating fluid.
[0009]
However, since the radial radial load and the axial thrust load act on the rotating impeller 3, these are supported and the minute gap Q is supported. 1 ~ Q Three The following measures have been taken to ensure
[0010]
First, as shown in FIGS. 9 to 11, a radial dynamic pressure generating groove 140 for supporting a radial load of the impeller 3 (sleeve 30) is formed on the outer peripheral surface of the shaft portion 20 constituting the bearing 2. (See a single hatched portion in FIG. 10). These radial dynamic pressure generating grooves 140 have a spiral shape called a spiral groove, and the depth is uniformly processed to be substantially constant.
[0011]
Second, as shown in FIGS. 9 and 12 to 14, a plurality of front thrust dynamic pressure generating grooves 141 for supporting the thrust load of the impeller 3 are provided on the inner surface of the front plate portion 21. Yes. These front-side thrust dynamic pressure generating grooves 141 have a spiral shape, and, like the radial dynamic pressure generating grooves 140, are uniformly processed at a substantially constant depth. On the other hand, a plurality of rear thrust dynamic pressure generating grooves 142 for supporting the thrust load of the impeller 3 are also provided on the inner surface of the rear plate portion 22. FIG. 12 shows an aspect in which the front thrust dynamic pressure generating groove 141 or the rear thrust dynamic pressure generating groove 142 is partially provided on each inner surface of the front plate portion 21 or the rear plate portion 22. Reference numeral 13 denotes an aspect in which the front plate portion 21 or the rear plate portion 22 is provided so as to continue from the outer periphery, ie, the outer edge, on each inner surface to the inner periphery, ie, the outer periphery of the shaft portion 20.
[0012]
By applying such a device, the rotating impeller 3 causes the radial dynamic pressure and thrust to flow into the blood flowing in the radial dynamic pressure generating groove 140, the front thrust dynamic pressure generating groove 141, or the rear thrust dynamic pressure generating groove 142. Since the dynamic pressure is generated and is kept in a non-contact state floating on the bearing 2, smooth rotation is possible, which leads to improvement in the stability and durability of blood supply as an artificial heart pump. .
[0013]
[Patent Document 1]
JP 7-136247 A (page 2-3, FIG. 1)
[0014]
[Problems to be solved by the invention]
By the way, since the target fluid to be handled is blood and the target to be used is a human or animal, an artificial heart pump is strongly required not to cause hemolysis and thrombus for a long period of time as a fatal solution problem. The Hemolysis is a phenomenon in which the surface membrane of erythrocytes in blood is damaged and its function is lost, and thrombus is a phenomenon in which blood aggregates and blocks blood flow paths such as blood vessels.
[0015]
However, in the artificial heart pump described above, the minute gap Q formed by the sleeve 30 forming the impeller 3, the shaft portion 20 forming the bearing 2, the front plate portion 21 and the rear plate portion 22. 1 ~ Q Three , Hemolysis and thrombus were frequent. Because this minute gap Q 1 ~ Q Three In the past, an extremely narrow gap size of several μm to several tens of μm was set, so that the blood itself is difficult to flow. Regarding hemolysis, the relative rotation speed difference of the impeller 3 with respect to the bearing 2 This is because a great amount of shear stress acts on the flowing blood, and the red blood cells are damaged by this shear stress. Thrombosis occurs when the flow rate of the blood itself is slow or the flow rate is low, not to mention the influence of the surface roughness and affinity of the material at the location where the flowing blood contacts. Then, it is thought, and then, the minute gap Q 1 ~ Q Three This is because it was a disadvantageous factor.
[0016]
As a technique for solving such problems of hemolysis and thrombus, a micro gap Q is used. 1 ~ Q Three It is conceivable to simply enlarge the gap size. However, if it is enlarged too much, the effectiveness of the radial dynamic pressure and the thrust dynamic pressure for supporting the radial load and the thrust load of the rotating impeller 3 is significantly reduced. Since the smooth rotation of the gear 3 with respect to the bearing 2 leading to the stability and durability of the bearing is hindered, the gap size is limited to about 30 μm to 40 μm, and this can sufficiently solve the problems of hemolysis and thrombus. There wasn't.
[0017]
Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide an artificial heart pump that can suppress hemolysis and thrombus generation while maintaining the stability and durability of blood supply. Is.
[0018]
To achieve the above object, an artificial heart pump according to the present invention comprises a housing, a bearing fixed in the housing, and comprising a shaft portion, a front plate portion projecting radially outward from the shaft portion, and a rear plate portion. And a through hole facing the outer peripheral surface of the shaft portion with a minute gap therebetween, and a front surface and a rear surface facing the inner surface of the front plate portion and the rear plate portion with a minute gap therebetween. An impeller rotatably supported in the housing, and by the rotation of the impeller, blood is taken from the front in the axial direction and pumped radially outward, and the pumped blood A part is introduced into a minute gap between the inner surface of the rear plate portion and the rear surface of the impeller, a minute gap between the outer peripheral surface of the shaft portion and the through hole of the impeller, and the inner surface of the front plate portion The feather Of via a small gap between the front, in the artificial heart pump for combining the blood to be taken, on the outer circumferential surface of the shaft portion for supporting the radial load of the impeller Generate radial dynamic pressure A plurality of radial dynamic pressure generating grooves are provided, and the inner surfaces of the front plate portion and the rear plate portion support the thrust load of the impeller. Generates thrust dynamic pressure A plurality of front thrust dynamic pressure generating grooves and a plurality of rear thrust dynamic pressure generating grooves are provided, and at least each of the radial dynamic pressure generating grooves, the front thrust dynamic pressure generating grooves, and the rear thrust dynamic pressure generating grooves is provided. One is deeper than the other radial dynamic pressure generating grooves, the front thrust dynamic pressure generating grooves, and the rear thrust dynamic pressure generating grooves. In addition to the large amount of blood flow, the radial dynamic pressure and the thrust dynamic pressure generated are lower than the other radial dynamic pressure generating grooves, the front thrust dynamic pressure generating grooves, and the rear thrust dynamic pressure generating grooves. It is characterized by that.
[0019]
This allows a large amount of blood to be allowed in the deep radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove, so that a part of the pumped blood flows as a lubricating fluid. In the minute gap between the inner surface of the plate part and the rear surface of the impeller, the minute gap between the outer peripheral surface of the shaft part and the through hole of the impeller, and the minute gap between the inner surface of the front plate part and the front surface of the impeller, the blood itself The amount of fluid increases, and hemolysis and thrombus generation are suppressed. In addition, in the other radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove, the radial dynamic pressure and the thrust dynamic pressure are effectively generated in the flowing blood. Rotation is possible, and the stability and durability of the blood supply as an artificial heart pump is maintained.
[0020]
Here, based on practicality, the radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove having a deep depth are the other radial dynamic pressure generating grooves, the front side, The depth is preferably 10 times or more deeper than the thrust dynamic pressure generating groove and the rear thrust dynamic pressure generating groove.
[0021]
Further, in order to more effectively suppress the generation of hemolysis and thrombus, the radial dynamic pressure generating groove having a deep depth, the front thrust dynamic pressure generating groove, and the rear side from the viewpoint of increasing the flow amount of the blood itself. The thrust dynamic pressure generating groove is preferably wider than the other radial dynamic pressure generating grooves, the front thrust dynamic pressure generating grooves, and the rear thrust dynamic pressure generating grooves.
[0022]
Further, for the purpose of ensuring the generation of effective radial dynamic pressure and thrust dynamic pressure and facilitating the flow of blood itself, the radial dynamic pressure generating groove is spiral, and the front thrust dynamic pressure generating groove and the rear The side thrust dynamic pressure generating groove is spiral, and the radial dynamic pressure generating groove having a deep depth is continuous from the inner surface of the rear plate portion to the inner surface of the front plate portion in the shaft portion, The deep thrust dynamic pressure generating groove and the rear thrust dynamic pressure generating groove having a deep depth are continuous from the outer edge of each of the front plate portion and the rear plate portion to the outer peripheral surface of the shaft portion. Good.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors maintain the stability and durability of the blood supply as an artificial heart pump with respect to the suppression of hemolysis and thrombus in the minute gap between the impeller and the bearing, which is a fatal solution to the artificial heart pump. As a result, the present invention is focused on various dynamic pressure generating grooves formed in a bearing for rotatably supporting the impeller in a floating state in the minute gap. It came to an eggplant.
[0024]
That is, the major feature of the artificial heart pump of the present invention is that a plurality of radial dynamic pressure generating grooves, front thrust dynamic pressure generating grooves and rear side dynamics are formed on the shaft portion, the front plate portion, and the rear plate portion forming the bearing. The pressure generating groove is composed of a shallow depth and a deep depth, and the shallow depth flows to maintain the stability and durability of the blood supply as an artificial heart pump. It plays the role of ensuring effective rotation of the blood to ensure smooth rotation of the impeller relative to the bearing, and the other deep part is to ensure the flow rate of the blood itself in order to prevent hemolysis and thrombus formation. Fulfill.
[0025]
Hereinafter, embodiments of the artificial heart pump of the present invention will be described in detail with reference to the drawings. First, a first embodiment of the present invention will be described. FIG. 1 is a schematic diagram illustrating a lubrication mechanism of an artificial heart pump according to the first embodiment, FIG. 2 is a development view of an outer peripheral surface of a shaft portion showing a radial dynamic pressure generating groove of a bearing in the artificial heart pump, and FIG. Fig. 4 is a cross-sectional view of the outer peripheral surface of the shaft portion showing a cross section orthogonal to the radial dynamic pressure generating groove in Fig. 4, and Fig. 4 is an inner surface of the front plate portion (or rear plate portion) showing the thrust dynamic pressure generating groove of the bearing in the artificial heart pump. FIG. 5 is a circumferential sectional view of the inner surface of the front plate portion showing a cross section orthogonal to the thrust dynamic pressure generating groove in FIG. In the figure, portions having the same names and the same functions as those in FIGS. 8 and 9 are denoted by the same reference numerals, and redundant description is omitted here, and different points will be described. The same applies to the second embodiment to be described later.
[0026]
In the first embodiment, first, as shown in FIGS. 1 to 3, a radial motion for supporting the radial load of the impeller 3 (sleeve 30) is provided on the outer peripheral surface of the shaft portion 20 constituting the bearing 2. A plurality of pressure generating grooves 40 are partially provided (six are shown in FIG. 2). These radial dynamic pressure generating grooves 40 have a spiral shape called a spiral groove, and are individually processed to have a substantially constant depth.
[0027]
Here, the radial dynamic pressure generating groove 40 includes a pair of first radial dynamic pressure generating grooves 40a (refer to a double hatched portion in FIG. 2) disposed at symmetrical positions, and a second between them. It consists of a radial dynamic pressure generating groove 40b (see the single hatched portion in FIG. 2), and the depth sa of the first radial dynamic pressure generating groove 40a is greater than the depth sb of the second radial dynamic pressure generating groove 40b. Deeply formed. For example, the depth sa of the first radial dynamic pressure generating groove 40a is about 500 μm to 600 μm, while the depth sb of the second radial dynamic pressure generating groove 40b is about several tens of μm.
[0028]
As shown in FIGS. 1, 4, and 5, a plurality of front thrust dynamic pressure generating grooves 41 for supporting the thrust load of the impeller 3 are partially provided on the inner surface of the front plate portion 21 (FIG. 4). 6 are shown). These front thrust dynamic pressure generating grooves 41 have a spiral shape and are each processed to have a substantially constant depth in the same manner as the radial dynamic pressure generating grooves 40.
[0029]
Here, the front thrust dynamic pressure generating groove 41 is a pair of first front thrust dynamic pressure generating grooves 41a (refer to the double hatched portion in FIG. 4) disposed at symmetrical positions, and the first thrust dynamic pressure generating grooves 41 disposed therebetween. 2, and the depth ta of the first front thrust dynamic pressure generating groove 41a is that of the second front thrust dynamic pressure generating groove 41b. It is formed deeper than the depth tb. For example, the depth ta of the first front thrust dynamic pressure generating groove 41a is about 500 μm to 600 μm, similarly to the depth sa of the first radial dynamic pressure generating groove 40a, while the second front thrust dynamic pressure generating groove 41a is The depth sb of the generation groove 41b is about several tens of μm, similar to the depth sb of the second radial dynamic pressure generation groove 40b.
[0030]
Further, a plurality of rear thrust dynamic pressure generating grooves 42 for supporting the thrust load of the impeller 3 are provided on the inner surface of the rear plate portion 22 in the same manner as described above. The pressure generating groove 42 includes a first front thrust dynamic pressure generating groove 42a having a deep depth and a second front thrust dynamic pressure generating groove 41b having a shallow depth.
[0031]
By configuring the various dynamic pressure generating grooves in this way, the first radial dynamic pressure generating groove 40a, the first front thrust dynamic pressure generating groove 41a, and the first rear side, which are deep dynamic pressure generating grooves, are formed. Since a large amount of blood can be allowed in the thrust dynamic pressure generating groove 42a, the sleeve 30 forming the impeller 3, the shaft portion 20 forming the bearing 2, the front plate portion 21 and the like, in which a part of the pumped blood flows as a lubricating fluid. And a minute gap Q formed by the rear plate portion 22. 1 ~ Q Three In this case, the flow amount of the blood itself increases, and hemolysis and thrombus generation are suppressed. Moreover, in the second radial dynamic pressure generating groove 40b, the second front thrust dynamic pressure generating groove 41b, and the second rear thrust dynamic pressure generating groove 42b, which are shallow dynamic pressure generating grooves, the flowing blood is Since the radial dynamic pressure and the thrust dynamic pressure are effectively generated, the impeller 3 can be smoothly rotated with respect to the bearing 2, and the stability and durability of blood supply as an artificial heart pump can be maintained.
[0032]
In order to secure a practical flow amount of blood that can suppress the generation of hemolysis and thrombus, the first radial dynamic pressure generating groove 40a, the first front thrust dynamic pressure generating groove 41a, and the first rear The depths sa and ta of the side thrust dynamic pressure generating groove 42a are the depths of the second radial dynamic pressure generating groove 40b, the second front thrust dynamic pressure generating groove 41b, and the second rear thrust dynamic pressure generating groove 42b. It is preferably 10 times or more deeper than sb and tb.
[0033]
In order to more effectively suppress the generation of hemolysis and thrombus, the first radial dynamic pressure generating groove 40a and the first front thrust movement shown in FIGS. The widths ua and va of the pressure generating groove 41a and the first rear thrust dynamic pressure generating groove 42a are equal to the second radial dynamic pressure generating groove 40b, the second front thrust dynamic pressure generating groove 41b, and the second rear thrust. It is preferable that the dynamic pressure generating groove 42b is wider than the widths ub and vb.
[0034]
Next, a second embodiment of the present invention will be described with reference to FIGS. 6 is a developed view of the outer peripheral surface of the shaft portion showing the radial dynamic pressure generating groove of the bearing in the artificial heart pump of the second embodiment, and FIG. 7 is a front plate portion showing the thrust dynamic pressure generating groove of the bearing in the artificial heart pump ( (Or rear plate portion) is a plan view of the inner surface. The feature of the second embodiment is that the first radial dynamic pressure generating groove 40a, the first front thrust dynamic pressure generating groove 41a and the first rear thrust dynamic pressure generating groove 42a in the first embodiment are deformed, It is in the point which made the flow of blood itself easy.
[0035]
That is, as shown in FIG. 6, the first radial dynamic pressure generating groove 40 a is formed to be continuous between the front and rear ends of the shaft portion 20, that is, from the inner surface of the rear plate portion 22 to the inner surface of the front plate portion 21. Has been. Further, as shown in FIG. 7, the first front thrust dynamic pressure generating groove 41 a is formed so as to continue from the outer edge of the front plate portion 21 to the outer peripheral surface of the shaft portion 20. Further, the first rear thrust dynamic pressure generating groove 42a is also formed to be continuous between the outer edge of the rear plate portion 22 and the outer peripheral surface of the shaft portion 20 in the same manner. Accordingly, the blood itself easily and continuously flows along the first radial dynamic pressure generating groove 40a, the first front thrust dynamic pressure generating groove 41a, and the first rear thrust dynamic pressure generating groove 42a. It is possible to suppress hemolysis and thrombus more effectively.
[0036]
Incidentally, the second radial dynamic pressure generating groove 40b does not reach the front and rear ends of the shaft portion 20, and the second front thrust dynamic pressure generating groove 41b and the second rear thrust dynamic pressure generating groove 42b are formed on the front plate. Although the outer edge of each of the portion 21 and the rear plate portion 22 is not reached, there is no problem in the generation of effective radial dynamic pressure and thrust dynamic pressure.
[0037]
In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the second radial dynamic pressure generating groove 40b is formed to continue to the front and rear ends of the shaft portion 20, and the second front thrust dynamic pressure generating groove 41b and the second rear thrust dynamic pressure generating groove 42b are Of course, it may be formed so as to continue from the outer edge of each of the front plate portion 21 and the rear plate portion 22 to the outer peripheral surface of the shaft portion 20. Further, the front thrust dynamic pressure generating groove 41 and the rear thrust dynamic pressure generating groove 42 are not limited to the spiral shape as described above, and may be, for example, radial.
[0038]
【The invention's effect】
As described above, according to the artificial heart pump of the present invention, the bearing includes the housing, the shaft portion fixed to the housing, and the front plate portion and the rear plate portion protruding radially outward from the shaft portion. And a through hole facing the outer peripheral surface of the shaft portion with a minute gap therebetween, and a front surface and a rear surface facing the inner surface of the front plate portion and the rear plate portion with a minute gap therebetween. An impeller rotatably supported in the housing, and by the rotation of the impeller, blood is taken from the front in the axial direction and pumped radially outward, and the pumped blood A part is introduced into a minute gap between the inner surface of the rear plate portion and the rear surface of the impeller, a minute gap between the outer peripheral surface of the shaft portion and the through hole of the impeller, and the inner surface of the front plate portion Of the impeller In an artificial heart pump that joins the blood to be taken in through a minute gap with the surface, a plurality of radial dynamic pressure generating grooves for supporting a radial load of the impeller are provided on the outer peripheral surface of the shaft portion. A plurality of front thrust dynamic pressure generating grooves and a plurality of rear thrust dynamic pressure generating grooves for supporting the thrust load of the impeller are provided on each inner surface of the front plate portion and the rear plate portion. At least one of the dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove is the other radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear side. The depth is deeper than the thrust dynamic pressure generating groove. In other words, since a large amount of blood can be allowed in the deep radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove, the impeller in which a part of the pumped blood flows as a lubricating fluid and In each minute gap formed by the bearing, the flow amount of the blood itself increases, thereby suppressing the occurrence of hemolysis and thrombus. Moreover, in the other radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove, the radial dynamic pressure and the thrust dynamic pressure are effectively generated in the flowing blood. As a result, the stability and durability of the blood supply as an artificial heart pump can be maintained.
[0039]
Here, the radial dynamic pressure generating groove having a deep depth, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove are the other radial dynamic pressure generating grooves, the front thrust dynamic pressure generating grooves, When the depth is 10 times or more deeper than the rear thrust dynamic pressure generating groove, it is possible to sufficiently secure a practical flow amount of blood itself capable of suppressing hemolysis and thrombus generation.
[0040]
Further, the radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove having a deep depth are the other radial dynamic pressure generating grooves, the front thrust dynamic pressure generating grooves, and If the width is wider than the rear thrust dynamic pressure generating groove, the amount of blood itself increases, so that hemolysis and thrombus generation can be more effectively suppressed.
[0041]
Further, the radial dynamic pressure generating groove is spiral, the front thrust dynamic pressure generating groove and the rear thrust dynamic pressure generating groove are spiral, and the radial dynamic pressure generating groove having a deep depth is formed on the shaft. The front thrust dynamic pressure generating groove and the rear thrust dynamic pressure generating groove having a deep depth are continuous between the inner surface of the rear plate portion and the inner surface of the front plate portion of the front plate portion, and the front plate portion and If it is continuous from the outer edge of each of the rear plate portions to the outer peripheral surface of the shaft portion, it is a form surface unique to the radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove. Therefore, generation of effective radial dynamic pressure and thrust dynamic pressure can be ensured, and in addition, blood itself can easily flow.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a lubrication mechanism of an artificial heart pump according to a first embodiment of the present invention.
FIG. 2 is a development view of an outer peripheral surface of a shaft portion showing a radial dynamic pressure generating groove of a bearing in the first embodiment.
3 is a cross-sectional view of an outer peripheral surface of a shaft portion in FIG.
FIG. 4 is a plan view of an inner surface of a front plate portion showing a thrust dynamic pressure generating groove of the bearing in the first embodiment.
5 is a circumferential sectional view of an inner surface of a front plate portion in FIG. 4;
FIG. 6 is a development view of an outer peripheral surface of a shaft portion showing a radial dynamic pressure generating groove of a bearing in an artificial heart pump according to a second embodiment of the present invention.
FIG. 7 is a plan view of an inner surface of a front plate portion showing a thrust dynamic pressure generating groove of a bearing in a second embodiment.
FIG. 8 is a longitudinal sectional view of a main part showing a configuration of a general artificial heart pump.
FIG. 9 is a schematic diagram for explaining a lubrication mechanism of a conventional artificial heart pump.
FIG. 10 is a development view of an outer peripheral surface of a shaft portion showing a radial dynamic pressure generating groove of a conventional bearing.
11 is a cross-sectional view of the outer peripheral surface of the shaft portion in FIG.
FIG. 12 is a plan view of an inner surface of a front plate portion showing a thrust dynamic pressure generating groove of a conventional bearing.
FIG. 13 is a plan view of an inner surface of a front plate portion showing a thrust dynamic pressure generating groove of another conventional bearing.
14 is a circumferential sectional view of the inner surface of the front plate portion in FIG. 12 or FIG. 13;
[Explanation of symbols]
1 Housing
2 Bearing
3 impeller
10 Front housing
11 Rear housing
12 Inlet connection port
13 Discharge side connection port
14 Rotating magnetic field generator
20 Shaft
21 Front plate
22 Rear plate
23 Tip
24 Shaft support
30 sleeves
31 Rear shroud
32 Front shroud
33 feathers
34 Permanent magnet
35 lid
40 Radial dynamic pressure generating groove
40a First radial dynamic pressure generating groove (a deep dynamic pressure generating groove 40)
40b Second radial dynamic pressure generating groove (shallow dynamic pressure generating groove 40)
41 Front thrust dynamic pressure generating groove
41a First front thrust dynamic pressure generating groove (a deep dynamic pressure generating groove 41)
41b Second front thrust dynamic pressure generating groove (shallow depth dynamic pressure generating groove 41)
42 Rear thrust dynamic pressure generating groove
42a First rear thrust dynamic pressure generating groove (a deep dynamic pressure generating groove 42)
42b Second rear thrust dynamic pressure generating groove (shallow depth dynamic pressure generating groove 42)

Claims (3)

ハウジングと、このハウジング内に固定され、軸部及びこの軸部から径方向外方に突出する前側プレート部、後側プレート部よりなる軸受と、前記軸部の外周面に微小間隙を隔てて対向する貫通孔とともに、前記前側プレート部、後側プレート部の各内面に微小間隙を隔てて対向する前面、後面を有し、前記軸受に対し前記ハウジング内で回転可能に支持された羽根車と、を備えていて、前記羽根車の回転により、軸方向前方から血液を取り込んで径方向外方へ圧送するとともに、この圧送された血液の一部を前記後側プレート部の内面と前記羽根車の後面との微小間隙に導き入れ、前記軸部の外周面と前記羽根車の貫通孔との微小間隙、及び前記前側プレート部の内面と前記羽根車の前面との微小間隙を経由して、取り込まれる前記血液に合流させる人工心臓ポンプにおいて、
前記軸部の外周面には前記羽根車のラジアル荷重を支持するためのラジアル動圧を発生するラジアル動圧発生溝が複数設けられ、前記前側プレート部、後側プレート部の各内面には前記羽根車のスラスト荷重を支持するためのスラスト動圧を発生する前側スラスト動圧発生溝、後側スラスト動圧発生溝が複数ずつ設けられており、
前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び後側スラスト動圧発生溝のうちそれぞれの少なくとも１つが、他の前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝よりも深さが１０倍以上深いとともに血液の流動量が多く、他の前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝よりも発生する前記ラジアル動圧及び前記スラスト動圧が低いことを特徴とする人工心臓ポンプ。 A housing, a shaft fixed in the housing, and a bearing including a front plate portion and a rear plate portion projecting radially outward from the shaft portion, and an outer peripheral surface of the shaft portion are opposed to each other with a minute gap. An impeller that has a front surface and a rear surface that face each inner surface of the front plate portion and the rear plate portion with a minute gap therebetween, and is rotatably supported in the housing with respect to the bearing; The blood is taken in from the front in the axial direction by the rotation of the impeller and is pumped radially outward, and a part of the pumped blood is fed to the inner surface of the rear plate portion and the impeller. Taking in through a minute gap between the outer surface of the shaft portion and the through hole of the impeller and a minute gap between the inner surface of the front plate portion and the front surface of the impeller. To the blood In the artificial heart pump to flow,
A plurality of radial dynamic pressure generating grooves for generating a radial dynamic pressure for supporting the radial load of the impeller are provided on the outer peripheral surface of the shaft portion, and the inner surfaces of the front plate portion and the rear plate portion are each front thrust hydrodynamic grooves for generating a thrust dynamic pressure for supporting the thrust load of the impeller, the rear thrust hydrodynamic grooves are provided by a plurality,
At least one of the radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove is the other radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the The depth is more than 10 times deeper than the rear thrust dynamic pressure generating groove, and the amount of blood flow is larger. The other radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove An artificial heart pump characterized in that the radial dynamic pressure and the thrust dynamic pressure generated are lower. 深さの深い前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝は、他の前記ラジアル動圧発生溝、前記前側スラスト動圧発生溝、及び前記後側スラスト動圧発生溝よりも幅が広いことを特徴とする請求項１に記載の人工心臓ポンプ。The radial dynamic pressure generating groove, the front thrust dynamic pressure generating groove, and the rear thrust dynamic pressure generating groove having a deep depth are the other radial dynamic pressure generating grooves, the front thrust dynamic pressure generating grooves, and the rear The artificial heart pump according to claim 1 , wherein the artificial heart pump is wider than the side thrust dynamic pressure generating groove. 前記ラジアル動圧発生溝が螺旋状で、前記前側スラスト動圧発生溝及び前記後側スラスト動圧発生溝が渦巻状であって、
深さの深い前記ラジアル動圧発生溝が、前記軸部における前記後側プレート部の内面から前記前側プレート部の内面に至る間に連続し、深さの深い前記前側スラスト動圧発生溝及び前記後側スラスト動圧発生溝が、前記前側プレート部及び前記後側プレート部それぞれにおける外縁から前記軸部の外周面に至る間に連続していることを特徴とする請求項１又は２に記載の人工心臓ポンプ。The radial dynamic pressure generating groove is spiral, the front thrust dynamic pressure generating groove and the rear thrust dynamic pressure generating groove are spiral,
The radial dynamic pressure generating groove having a deep depth is continuous from the inner surface of the rear plate portion to the inner surface of the front plate portion in the shaft portion, and the front thrust dynamic pressure generating groove having a deep depth and the rear thrust dynamic pressure generating grooves, according to claim 1 or 2, characterized in that in succession while extending from the outer edge of each of the front plate portion and the rear plate portion on the outer peripheral surface of the shaft portion Artificial heart pump.
JP2003034927A 2003-02-13 2003-02-13 Artificial heart pump Expired - Lifetime JP4072721B2 (en)

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