Expander

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 ), and sliding surfaces of the piston ( 42 ) and the cylinder sleeve ( 41 ) are lubricated with oil supplied via an oil hole ( 32 c ). The piston ( 42 ) includes a top part ( 63 ) that is exposed to high-temperature, high-pressure steam within the expansion chamber ( 43 ), an end part ( 61 ) that abuts against the swash plate ( 31 ), and a middle part ( 62 ) that is present between the end part ( 61 ) and the top part ( 63 ) and is in sliding contact with the cylinder sleeve ( 41 ), the top part ( 63 ) being formed from a heat-resistant and corrosion-resistant material, the end part ( 61 ) being formed from a material having high surface pressure resistance, and the middle part ( 62 ) being formed from a material having high abrasion resistance. This enables the durability of the piston ( 42 ) of an axial piston cylinder type expander to be improved.

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 an axis (L) of the rotor; 
 the rotor ( 22 ) being rotated by supplying 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 ), and sliding surfaces of the piston ( 42 ) and the cylinder sleeve ( 41 ) being lubricated with oil;  
 characterized in that that piston ( 42 ) comprises a top part ( 63 ) that is exposed to high-temperature, high-pressure steam within expansion chamber ( 43 ), an end part ( 61 ) that abuts against a swash plate ( 31 ), and a middle part ( 62 ) that is present between the end part ( 61 ) and the top part ( 63 ) and is in sliding contact with the cylinder sleeve ( 41 ), the top part ( 63 ) being formed from a heat-resistant and corrosion-resistant material, the end part ( 61 ) being formed from a material having high surface pressure resistance, and the middle part ( 62 ) being formed from a material having high abrasion resistance.  
   
   
   
       2 . The expander according to  claim 1 , wherein a heat-insulating space ( 65 ) is provided between the top part ( 63 ) and the middle part ( 62 ).  
   
   
       3 . The expander according to,  claim 1  wherein a hollow space ( 62   a ) is formed in the middle part ( 62 ), an oil ring channel ( 63   b ) formed on an outer peripheral face of the top part ( 63 ) communicates with the hollow space ( 62   a ) via a first oil hole ( 63   c ), and a small diameter part ( 62   b ) formed on an outer peripheral face of the middle part ( 62 ) communicates with the hollow space ( 62   a ) via a second oil hole ( 62   c ).  
   
   
       4 . The expander according to  claim 2 , wherein a hollow space ( 62   a ) is formed in the middle part ( 62 ), an oil ring channel ( 63   b ) formed on an outer peripheral face of the top part ( 63 ) communicates with the hollow space ( 62   a ) via a first oil hole ( 63   c ), and a small diameter part ( 62   b ) formed on an outer peripheral face of the middle part ( 62 ) communicates with the hollow space ( 62   a ) via a second oil hole ( 62   c ).