Fluid powered starter with a variable turbine stator
A system for starting an engine is disclosed herein. The system includes a fluid powered turbine with a variable geometry stator. The variable geometry stator includes moveable members operable to selectively block fluid flow to the turbine.
1. A system comprising:
a source of compressed working fluid;
a turbine starter including:
a housing;
a turbine rotatably supported within the housing, the turbine having a plurality of vanes extending radially outward from a turbine disk;
a variable geometry stator positioned upstream of the turbine, the stator having a plurality of static stator vanes extending radially outward from a stator body and a plurality flow areas defined between adjacent pairs of stator vanes, wherein the variable geometry stator is configured to block a variable portion of one or more of the flow areas of the stator;
an actuation system operably coupled to the variable geometry stator; and
wherein the actuation system includes a cam positioned within the stator body.
2. The system of claim 1 , wherein the variable geometry stator is operable to control flow rate of the working fluid discharged to the turbine.
3. The system of claim 1 , wherein the variable geometry stator is operable to block a different portion of each of the plurality of flow areas at the same time.
4. The system of claim 1 , wherein the variable geometry stator is operable to block an equal portion of each of the plurality of flow areas at the same time.
5. The system of claim 1 , wherein the variable geometry stator is operable to variably block each of the flow areas between the stator vanes from 0% to 100%.
6. The system of claim 1 , wherein the cam is a rotatable cam.
7. The system of claim 6 , wherein the rotatable cam includes a plurality of separately rotatable cams.
8. The system of claim 7 , wherein each rotatable cam includes at least one actuation lobe.
9. The system of claim 1 , wherein the actuation system includes at least one of a linear electronic actuator and/or a rotational electronic actuator.
10. The system of claim 1 , further comprising a plurality of blocking members moveable between first and second positions corresponding to a fully open flow area and a fully closed flow area respectively between adjacent pairs of stator vanes.
11. The system of claim 10 , wherein the blocking members are positioned upstream of the stator vanes, downstream of the stator vanes, or between the stator vanes.
12. The system of claim 10 , wherein the blocking members include a pin positioned between an adjacent pair of stator vanes, the pin having a width substantially equivalent to a distance across a space between the adjacent stator vanes.
13. The system of claim 10 , wherein each blocking member extends across flow areas of at least two adjacent pairs of stator vanes.
14. The system of claim 10 , further comprising a resilient member engaged with each of the blocking members to urge the blocking members toward the first position.
15. The system of claim 1 , further comprising at least one of a controller, a temperature sensor, a pressure sensor and a speed sensor adapted to control the turbine starter during an engine start process.
16. A turbine starter comprising:
a housing having a fluid inlet and a fluid outlet;
a variable geometry stator having a plurality of stator vanes extending radially outward therefrom, the stator positioned within the housing downstream of the fluid inlet;
a stator flow area defined between each pair of adjacent stator vanes;
a movable member positioned to selectively block one or more of the stator flow areas; and
a turbine rotatably supported within the housing downstream of the stator; and
an actuation system having a cam positioned within the stator and coupled to the movable member, the actuation system operable for moving the movable member between first and second positions corresponding to a fully open flow area and a fully closed flow area, respectively.
17. The turbine starter of claim 16 , wherein the movable member is positioned upstream of the stator vanes, downstream of the vanes, or between the vanes.
18. The turbine starter of claim 16 , wherein the cam is a rotatable cam with at least one actuation lobe operably engageable with the movable member.
19. The turbine starter of claim 16 , wherein the actuation system includes at least one of a linear and a rotatable electronic actuator.
20. The combination valve of claim 19 , wherein the electronic actuator is operably coupled to the cam.
21. The turbine starter of claim 19 , wherein the electronic actuator is operably coupled directly to the movable member.
22. The turbine starter of claim 16 , wherein the moveable member includes a plurality of moveable members and each movable member operates independently from other moveable members.
23. The turbine starter of claim 16 , wherein the stator includes a housing adapted to pivot about a rotational axis to react against fluid flow.
24. The turbine starter of claim 23 , wherein the movable member is adapted to move between first and second positions in response to the pivoting of the stator housing.
25. A turbine stator comprising:
a body with a cavity formed between a hub and an outer perimeter;
a plurality of static airfoil shaped vanes extending radially outward from the outer perimeter;
a flow area defined between adjacent vanes;
a flow blocking member positioned between adjacent vanes, the flow blocking member movable between first and second positions, wherein the first and second positions corresponds to variably defined blockages of the flow area; and
an actuation device operably coupled to the flow blocking member to urge the flow blocking member toward one of the first and second positions when activated; and
wherein the actuation device includes a cam disposed in the cavity of the body.
26. The turbine stator of claim 25 , wherein the flow blocking device includes a structure slidable between the first and second positions corresponding to fully open and fully closed positions respectively.
27. The turbine stator of claim 26 , further comprising a resilient member coupled to the structure to urge the structure toward the other of the first and second positions when the actuation device is deactivated.
28. A method comprising:
transporting pressurized working fluid to a variable geometry turbine stator;
controlling the pressurized working fluid discharged from the turbine stator, wherein the controlling includes selectively blocking a portion of the flow of working fluid through flow areas formed between static vanes of the stator;
rotatingly driving a turbine with the working fluid;
rotating an engine to a starting speed with the turbine; and
wherein the controlling includes moving a flow blocking member to a desired position between a first position proximate a hub of the stator vanes to a second position proximate the tip of the stator vanes with an actuation cam positioned internal to the turbine stator.
29. The method of claim 28 , further comprising sensing a pressure of a working fluid, a temperature of the working fluid and/or the speed of the turbine.
30. The method of claim 29 , wherein the controlling is in response to the sensing.