Canned motor device

A canned motor device comprising:

• a base formed in a shape of a hollow cylinder that surrounds an axis, and defining an accommodating space;
• a fixed seat formed in a shape of a hollow cylinder that surrounds the axis, and disposed in said accommodating space;
• a motor unit including
• a case body that is disposed on said base,
• a stator that is sleeved on said case body and that is surrounded by said fixed seat,
• a rotor that is disposed in said case body, and
• an impeller that is connected to said rotor;
• a motor cover disposed on said base and covering said impeller;
• and
• a main cover located at one side of said base opposite to said motor cover along the axis, and having
• an inner surface that abuts against said base,
• an annular protrusion that protrudes from said inner surface, and that has an annular end surface spaced apart from said inner surface and airtightly abutting against said fixed seat, and
• an inner heat-dissipating space that is defined by said inner surface and said annular protrusion, and that is adjacent to said stator of said motor unit;
• wherein said annular protrusion of said main cover further has
• an inner annular surface interconnecting said annular end surface and said inner surface of said main cover, and adjacent to said inner heat-dissipating space of said main cover, and
• an outer annular surface opposite to said inner annular surface, and interconnecting said annular end surface and said inner surface;
• and
• wherein said main cover further has
• an outer heat-dissipating space defined by said inner surface and said annular protrusion, and adjacent to said outer annular surface of said annular protrusion, and
• a plurality of cover protrusions each of which protrudes from said outer annular surface and is connected to said inner surface.