Expansion engine

Abstract

An expander is provided in which a rotor ( 22 ) is rotated by supplying high-temperature, high-pressure steam to an expansion chamber ( 43 ) defined between a piston ( 42 ) and a cylinder sleeve ( 41 ) so that the piston ( 42 ) pushes a swash plate ( 31 ). Since an annular heat-insulating space ( 70 ) is formed in a rotor head ( 38 ) facing the expansion chamber ( 43 ), it is possible to suppress the escape, to the rotor ( 22 ), of the heat of high-temperature, high-pressure steam supplied to the expansion chamber ( 43 ), thereby preventing the heat efficiency from deteriorating. Moreover, since the expansion chamber ( 43 ) is sealed by interposing a metal gasket ( 36 ) between the end face of the cylinder sleeve ( 41 ) and the end face of the rotor head ( 38 ), in comparison with a case in which the expansion chamber ( 43 ) is sealed via a thick annular seal, unnecessary volume around the seal can be reduced, thus ensuring that the expander has a large volume ratio (expansion ratio) and thereby improving the thermal efficiency, which enables the output to be increased.

1 . An expander comprising: 
 a casing ( 11 );    a rotor ( 22 ) rotatably supported in the casing ( 11 ); and    an axial piston cylinder group ( 56 ) arranged annularly in the rotor ( 22 ) so as to surround the axis (L) of the rotor ( 22 ), the rotor ( 22 ) being rotated by supplying, via a rotary valve ( 71 ), high-temperature, high-pressure steam to an expansion chamber ( 43 ) defined between a piston ( 42 ) and a cylinder sleeve ( 41 ) of the axial piston cylinder group ( 56 );    characterized in that a heat-insulating space ( 70 ) is provided at a position facing the expansion chamber ( 43 ) of the rotor ( 22 ).    
   
   
       2 . The expander according to  claim 1 , wherein the rotor ( 22 ) is formed by joining, in the axial (L) direction of the rotor ( 22 ), a first rotor half ( 33 ,  34 ,  35 ) retaining the cylinder sleeve ( 41 ), which is separate from the first rotor half ( 33 ,  34 ,  35 ), and a second rotor half ( 38 ) housing the rotary valve ( 71 ), and the expansion chamber ( 43 ) is sealed by interposing a metal gasket ( 36 ) between end faces of the first rotor half ( 33 ,  34 ,  35 ) and the cylinder sleeve ( 41 ) and an end face of the second rotor half ( 38 ).  
   
   
       3 . The expander according to either  claim 1  or  claim 2 , wherein a cutout ( 57 ,  58 ) is formed circumferentially in the rotor ( 22 ), an outer peripheral face of the cylinder sleeve ( 41 ) being exposed through the cutout ( 57 ,  58 ).  
   
   
       4 . The expander according to  claim 3 , wherein the surroundings of the cutout ( 57 ,  58 ) are covered by a heat-insulating cover ( 40 ).