Electromagnetically driven pumps

An electromagnetically driven pump comrising:

• a casing adapted to house a rotatable unit comprised by an impeller and an armature and having a fluid-inlet opening to lead fluid into the casing to the impeller in a direction parallel to the rotational axis of said impeller;
• a stator having a frusto-spherical magnetically effective surface complementary to that of the armature and spaced therefrom to form an air gap;
• frusto-spherical bearing means for said rotatable unit having its convex part rotatable with the said unit and its concave part non-rotatably mounted;
• a fluid-tight wall of frusto-spherical formation and of magnetically permeable material fixedly located in the air gap between the armature and the stator;
• and
• an annular second wall extending generally radially between the impeller and the armature, said second wall comprising an outer annular portion and an inner rotary frictional seal means arranged to be operative between said second wall outer portion and said rotatable unit and resiliently urged in a direction parallel to the axis of rotation of the machine and to allow appreciable precessional freedom of motion of the axis of rotation of the rotatable unit about the geometric centre of the frusto-spherical bearing means, in which said second wall seal means comprises an annular resilient portion of which the inner margin bears frictionally and in sealing contact with the convex part of the bearing means upon which said margin exerts thrust upon the convex part in the direction of the axis of rotation thereof and thrust upon an annular frusto-spherical bush bearing carried by said fluid-tight wall, and sealing against the convex element of the bearing means by virtue of axial load imposed by said inner margin.

A machine comprising:

• a pump casing and an electric motor stator mounted in said casing;
• an electric motor armature and a pump impeller forming a rotor unit, the armature having a frusto-spherical shape;
• the armature and the stator being spaced apart to form an air gap;
• a magnetically permeable separating wall fixed in said gap;
• and frusto-spherical bearing means for the rotor unit which is prevented from axial movement toward the stator by the bearing means, which is supported by the separating wall, the bearing means comprising a rotating ball and a concave non-rotating bush;
• said impeller being fixedly attached to said ball by said spindle, said armature being fixedly attached to the equatorial region of said ball and spaced from said impeller, the region of the ball opposite the impeller cooperating with said bush to form a bearing;
• and a fixed second wall extending radially in the space between said armature and said impeller and having an inner portion which cooperates with the portion of the ball lying between the attachments of the armature and impeller to said ball to constitute a seal.