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Magnetically suspended and rotated rotor

  • US 5,326,344 A
  • Filed: 11/09/1992
  • Issued: 07/05/1994
  • Est. Priority Date: 04/04/1985
  • Status: Expired due to Term
First Claim
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1. A pump implantable in a human body having a circulatory system for pumping blood to provide a replacement for, or an assist to, a natural heart, comprising:

  • a housing constructed of or coated with a blood compatible material having an inlet passage and an outlet passage for connecting the pump into the circulatory system of the human body into which the pump is implanted, the housing having an impellor chamber defining walls fluidly interposed between the inlet passage and the outlet passage;

    an impellor constructed of or coated with a blood compatible material disposed in the housing impellor chamber and rotatable therein about an impellor rotation axis for drawing blood into the housing inlet passage and discharging blood from the housing outlet passage;

    magnetic suspension means for magnetically suspending the impellor in said pump chamber out of contact with the walls of the impellor chamber, comprising;

    permanent magnet impellor support comprising an assembly of permanent magnets mounted on the impellor and on the housing for exerting forces on the impellor tending to align the rotation axis of the impellor with a selected support axis of the housing while tending to drive the impellor axially away from a selected null position on said support axis at such times that the impellor is axially displaced from the null position;

    an electromagnet mounted on the housing and positioned thereon to exert a force directed along the support axis on portions of the permanent magnet impellor support means dispose on the impellor at such times that an electric current is passed through the electromagnet, the electromagnet thereby exerting an axial force on the rotor,electromagnet control means mounted on the housing for detecting a displacement of the impellor from a control position of the impellor on the support axis and passing a current through the electromagnet to drive the impellor toward the control position, the electromagnet control means comprising means for selecting the control position in a displaced relation to the null position along said support axis, whereby the permanent magnet rotor support means will exert a force on the impellor at such times that the impellor is in the control position, thereby enabling the permanent magnets of the permanent magnet impellor support means to balance a static force exerted axially on the impellor; and

    impellor drive means mounted on the housing for sensing a preselected physical quantity related to a flow of blood in said circulatory system and magnetically coupled to the impellor for rotating the impellor at a rate varying in accordance with a selected relationship to the value of said physical quantity, said physical quantity being a pressure in the inlet passage of the housing;

    wherein the inlet passage of the housing opening into the impellor chamber along the housing support axis and the outlet passage extends tangentially from portions of the impellor chamber displaced radially from the housing support axis and extending circumferentially about the impellor.

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