Centrifugal pump apparatus

A centrifugal pump apparatus including a housing having first and second chambers partitioned from each other by a dividing wall, an impeller rotatably provided in said first chamber along said dividing wall, for delivering fluid by centrifugal force during rotation, and a drive unit provided in said second chamber, for driving said impeller to rotate with said dividing wall being interposed, the centrifugal pump apparatus comprising:

• a first magnetic element provided in one surface of said impeller;
• a second magnetic element provided in an inner wall of said first chamber facing the one surface of said impeller, for attracting said first magnetic element;
• a third magnetic element provided in the other surface of said impeller and attracted by said drive unit;
• and
• a fluid outlet port for allowing said fluid to flow to the outside of said housing from an opening provided in a sidewall of said first chamber, wherein
• during rotation of said impeller, a first attractive force acting between said first and second magnetic elements and a second attractive force acting between said third magnetic element and said drive unit are balanced with each other substantially in a center of a movable range of said impeller in said first chamber,
• a first groove for hydrodynamic bearing is formed in the one surface of said impeller or in the inner wall of said first chamber facing the one surface and a second groove for hydrodynamic bearing is formed in the other surface of said impeller or in said dividing wall facing the other surface,
• each of the first and second magnetic elements is formed annularly around a rotation centerline of said impeller, and
• a corner of an end surface of said first or second magnetic element is chamfered such that the first attractive force on said opening side becomes smaller than the first attractive force on an opposite side of said opening when said impeller becomes eccentric toward said opening side due to hydrodynamic force.