Centrifugal pump apparatus

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

• a first magnetic element provided in a first surface of said impeller;
• a second magnetic element provided in a planar surface of said first chamber facing the first surface of said impeller, for attracting said first magnetic element;
• a third magnetic element provided in a second surface of said impeller and attracted by said drive unit during rotation of said impeller, a first attractive force between said first and second magnetic elements and a second attractive force between said third magnetic element and said drive unit causing said impeller to be located substantially in a center of a movable range of said impeller in said first chamber;
• a plurality of first grooves and a plurality of second grooves, wherein:
• said plurality of first grooves and said plurality of second grooves are formed in said planar surface of said first chamber facing said first surface of said impeller;
• said plurality of first grooves alternate with and are separate from said plurality of second grooves;
• said plurality of first grooves begin at a first outer diameter and end at a first inner diameter;
• and
• said plurality of second grooves begin at the first outer diameter and end at the first inner diameter;
• and
• a plurality of third grooves and a plurality of fourth grooves, wherein:
• said plurality of third grooves and said plurality of fourth grooves are formed in a planar surface of said diaphragm facing said second surface of said impeller;
• said plurality of third grooves alternate with and are separate from said plurality of fourth grooves;
• said plurality of third grooves begin at a second outer diameter and end at a second inner diameter;
• and
• said plurality of fourth grooves begin at the second outer diameter and end at the second inner diameter,
• wherein at least one of a width and a depth of said plurality of second grooves is different from that of said plurality of first grooves, and at least one of a width and a depth of said plurality of fourth grooves is different from that of said plurality of third grooves.