Patent ID: 6918336

Claim:
A rotary fluid machine comprising an operating part ( 49 , 57 ) housed within a casing ( 11 ), and a hermetically sealed lubrication chamber ( 102 ) defined within the casing ( 11 ), the operating part ( 49 , 57 ) converting into mechanical energy the thermal energy and the pressure energy of a working medium introduced into an operating chamber ( 82 , 84 ) sealed by a seal ( 47 , 48 , 78 , 79 ), and oil for lubricating at least the operating part ( 49 , 57 ) residing in the lubrication chamber ( 102 ); wherein a breather chamber ( 101 , 103 ) is provided in an upper part of the lubrication chamber ( 102 ), a working medium discharge chamber ( 90 ) into which the working medium is discharged from the operating chamber ( 82 , 84 ) is made to communicate with the breather chamber ( 101 , 103 ) via a breather passage (B 1 to B 4 ), a mixture of oil and the working medium that has leaked from the operating chamber ( 82 , 84 ) into the lubrication chamber ( 102 ) through the seal ( 47 , 48 , 78 , 79 ) is separated in the breather chamber ( 101 , 103 ), the separated oil is returned from the breather chamber ( 101 , 103 ) to the lubrication chamber ( 102 ), and the separated working medium is returned from the breather chamber ( 101 , 103 ) to the working medium discharge chamber ( 90 ) via the breather passage (B 1 to B 4 ) corresponding to the amount of working medium that has leaked.