Turbomachine

Abstract

According to a first aspect of the present invention there is provided a variable geometry turbine comprising: a turbine wheel mounted for rotation about a turbine axis within a housing, the housing defining an annular inlet surrounding the turbine wheel and defined between first and second inlet sidewalls, the annular inlet being divided into at least two axially offset inlet portions; a cylindrical sleeve axially movable across the annular inlet to vary the size of a gas flow path through the inlet; and a guide for guiding the movement of the cylindrical sleeve, the guide being at least partially located within the inlet at a radially extent of the inlet portions, and extending in an axial direction parallel to the turbine axis.

1 . A variable geometry turbine comprising:
 a turbine wheel mounted for rotation about a turbine axis within a housing, the housing defining an annular inlet surrounding the turbine wheel and defined between first and second inlet sidewalls, the annular inlet being divided into at least two axially offset inlet portions;   a cylindrical sleeve axially movable across the annular inlet to vary the size of a gas flow path through the inlet; and   a guide for guiding the movement of the cylindrical sleeve, the guide being at least partially located within the inlet at a radially extent of the inlet portions, and extending in an axial direction parallel to the turbine axis.   
     
     
         2 . The variable geometry turbine of  claim 1 , wherein the guide comprises one or more elongate members. 
     
     
         3 . The variable geometry turbine of  claim 1 , further comprising:
 one or more vanes located in one or both inlet portions, the one or more vanes dividing an inlet portion into at least two inlet passages,   and wherein the guide comprises:   one or more edges of the one or more vanes.   
     
     
         4 . A variable geometry turbine comprising:
 a turbine wheel mounted for rotation about a turbine axis within a housing;   the housing defining an annular inlet surrounding the turbine wheel and defined between first and second inlet sidewalls,   the annular inlet being divided into at least two axially offset inlet portions by a baffle,   an inlet portion being divided into at least two inlet passages by a vane; and   a cylindrical sleeve axially movable across the annular inlet to vary the size of a gas flow path through the inlet;   wherein one or more of: a portion of an extremity of the baffle, a portion of an extremity of the vane and/or a leading end of the sleeve is provided with an inclined surface for facilitating movement of the sleeve across the baffle and/or vane.   
     
     
         5 . The variable geometry turbine of  claim 4 , wherein an inner diameter of the sleeve is greater than an outer diameter of the inlet portion, and wherein:
 one or more of: a radially outer portion of the baffle, a radially outer portion of the vane and/or a radially inner portion of a leading end of the sleeve is provided with an inclined surface for facilitating movement of the sleeve across the baffle and/or vane.   
     
     
         6 . The variable geometry turbine of  claim 4 , wherein the vane extends to a greater radial extent than the baffle, and at least the vane is provided with the inclined surface. 
     
     
         7 . The variable geometry turbine of  claim 4 , wherein the vane extends to a greater radial extent than the baffle, a leading end of the sleeve is provided with one or more discrete inclined surfaces distributed around a circumference of the sleeve, the location or locations of which coincide with a location of a vane. 
     
     
         8 . The variable geometry turbine of  claim 4 , wherein the baffle extends to a greater radial extent than the vane, and at least the baffle is provided with the inclined surface. 
     
     
         9 . The variable geometry turbine of  claim 4 , wherein the inclined surface is one or more of a bevel, a chamfer and/or a rounded edge. 
     
     
         10 . A variable geometry turbine comprising:
 a turbine wheel mounted for rotation about a turbine axis within a housing, the housing defining an annular inlet surrounding the turbine wheel and defined between first and second inlet sidewalls, the annular inlet being divided into at least two axially offset inlet portions;   a cylindrical sleeve structure axially movable across the annular inlet to vary the size of a gas flow path through the inlet; and   wherein the cylindrical sleeve structure extends across the entire width of the inlet, such that a first end of the sleeve structure is supported within or by the first inlet side wall, or a body defining that wall, and a second opposite end of the sleeve structure is supported within or by the second sidewall, or a body defining that wall;   and wherein the sleeve structure comprises one or more apertures locatable within the inlet to, upon movement of the sleeve structure, vary the size of a gas flow path through the inlet.   
     
     
         11 . The variable geometry turbine of  claim 10 , wherein the sleeve structure comprises a sleeve provided with the one or more apertures. 
     
     
         12 . The variable geometry turbine of  claim 10 , wherein the sleeve structure comprises a sleeve section and one or more support struts. 
     
     
         13 . The variable geometry turbine of  claim 10 , wherein the sleeve structure comprises a first sleeve section, and a second sleeve section, the first and second sleeve sections being joined and axially separated by one or more support struts. 
     
     
         14 . The variable geometry turbine of  claim 13 , wherein the one or more support struts are attached to the sleeve section, and/or the first sleeve section, and/or the second sleeve section. 
     
     
         15 . The variable geometry turbine of  claim 13 , wherein the one or more support struts are integral to the sleeve section, and/or the first sleeve section, and/or the second sleeve section. 
     
     
         16 . The variable geometry turbine of  claim 13 , wherein the one or more support struts are aligned with leading or trailing edges of vanes, or other structures, provided in one or both inlet portions. 
     
     
         17 . A variable geometry turbine comprising:
 a turbine wheel mounted for rotation about a turbine axis within a housing, the housing defining an annular inlet surrounding the turbine wheel and defined between first and second inlet sidewalls, the annular inlet being divided into at least two axially offset inlet portions;   a sleeve assembly, comprising a sleeve that is movable in a direction parallel to the turbine axis and across the annular inlet to vary the size of a gas flow path through the inlet, and an actuator for affecting movement of the sleeve;   wherein a helical interface is present in the sleeve assembly, the helical interface being arranged to induce, in use, helical movement of a part of the sleeve assembly.   
     
     
         18 . The variable geometry turbine of  claim 17 , wherein the sleeve comprises the helical interface, and the sleeve is arranged to move helically. 
     
     
         19 . The variable geometry turbine of  claim 18 , wherein the actuator comprises a rotatable collar that surrounds, or is surrounded by, the sleeve, the rotatable collar being fixed in position in an axial direction, and rotatable to move the sleeve helically. 
     
     
         20 . The variable geometry turbine of  claim 17 , wherein the sleeve assembly further comprises a guide or driver for guiding or driving movement of the sleeve in an axial and/or helical manner.