Rotary atomizing-head type coating machine

A rotary atomizing head type coating machine, having a tubular housing internally defining a motor compartment, an air motor accommodated in said motor compartment of said housing to drive a rotational shaft by a turbine, a rotary atomizing head mounted on a fore end portion of said rotational shaft of said air motor on the front side of said housing, a paint passage carrying a paint to be supplied to said rotary atomizing head, a turbine air passage provided in said housing and carrying turbine air for driving a turbine of said air motor, an exhaust air passage provided in said housing and carrying exhaust air which is discharged from a turbine chamber of said air motor after driving said turbine and finally discharged out of the machine,

• the coating machine comprising:
• a dual passage extended through said housing from a turbine chamber of said air motor, said dual passage having inner and outer passages arranged in concentric relation with each other;
• said inner passage of said dual passage being formed to serve as said exhaust air passage;
• and
• said outer passage of said dual passage being formed to serve as said heat insulating air passage and carrying heat insulating air of a higher temperature as compared with said exhaust air.