Perfected helicopter drive with air oil separator

1. A drive ( 6 ) for a helicopter ( 1 ), comprising:

at least one rotary member ( 10 , 11 );

a casing ( 8 ) housing said rotary member ( 10 , 11 ) and defining a compartment ( 9 ) containing a lubricating fluid in an oil bath and air;

a separating device ( 23 ) for separating said lubricating fluid from a mixture of atomized lubricating fluid and said air and retaining said lubricating fluid inside said casing ( 8 ) in the presence of airflow outwards of said casing ( 8 ) and produced by pressure gradients between said compartment ( 9 ) and the outside;

a seal ( 14 ) housed into said casing ( 8 ) between said at least one rotary member ( 10 , 11 ) and said casing ( 8 ) to retain said lubricating fluid inside said compartment( 9 ); and

an annular chamber ( 40 ) housed inside said casing ( 8 ) and defined between said seal ( 14 ) and an opening ( 20 ) of said compartment ( 9 ) located at one end of said casing ( 8 );

said separating device ( 23 ) being movable angularly about an axis (A) and angularly integral with said rotary member ( 10 , 11 ) to centrifugally separate said lubricating fluid from said air radially with respect to said axis (A);

said chamber ( 40 ) being fluidly connected with said separating device ( 23 ) so as to receive, in use, said air separated from said lubricating fluid by said separating device ( 23 );

said rotary member ( 10 , 11 ) comprising a tubular body ( 16 ) wherein said separating device ( 23 ) being fitted rigidly inside said tubular body ( 16 );

said tubular body ( 16 ) comprising a number of radial holes ( 18 ) and housing said separating device ( 23 ) comprising a case ( 27 );

said case ( 27 ) comprising an inlet ( 28 ) receiving said mixture of said atomized lubricating fluid and said air and defining a number of radial outlets ( 29 ) directed towards said radial holes ( 18 ) fluidly connected to said chamber ( 40 );

said case ( 27 ) being separate from and housed within said tubular body ( 16 );

said case ( 27 ) housing a filter ( 32 ) arranged in a position interposed axially between said inlet ( 28 ) and said outlets ( 29 ), and a sleeve ( 34 ) separate from said filter ( 32 ) and arranged on the side of said filter ( 32 ) axially opposite with respect to said outlets ( 29 );

said filter ( 32 ) occupying the whole cross section of said case ( 27 ) in a plane perpendicular to said axis (A) so as to interfere completely with any flow directed towards said outlets ( 29 ) or coming from said outlets ( 29 );

said sleeve ( 34 ) comprising a peripheral surface ( 30 , 31 ) defining a return path by which to feed said lubricating fluid, separated from said airflow, back inwards of said compartment ( 9 );

said peripheral surface ( 30 , 31 ) comprising at least one portion ( 30 ) tapering with respect to said axis (A) to facilitate drainage of said lubricating fluid.

2. The drive as claimed in claim 1 , wherein said rotary member ( 10 , 11 ) and said separating device ( 23 ) are mounted coaxially with each other.

3. The drive as claimed in claim 2 , wherein said separating device ( 23 ) is housed inside said rotary member ( 10 , 11 ).

4. The drive as claimed in claim 1 , further comprising a drain conduit ( 35 ) originating radially from the chamber ( 40 ) and adapted to drain any oil droplets escaping separating device( 23 ).

5. The drive as claimed in claim 1 , wherein said case ( 27 ) is radially interposed between said tubular body ( 16 ) on one side and said filter ( 32 ) and said sleeve ( 34 ) on the other side.

6. The drive as claimed in claim 1 , wherein sleeve ( 34 ) is separate from both said filter ( 32 ) and said case ( 27 ).