Variable vane lever arm
A vane arm has: a first end and a second end; a shank extending between the first end and the second end and having a first face and a second face; a first hole in the shank proximate the first end; a second hole in the shank proximate the second end; and a transverse groove in the first face intersecting the second hole. The transverse groove has: a base; a first open end and a second open end; a first side face and a second side face. The transverse groove first side face and second side face converge toward each other from the first open end to the second open end.
1 . A vane arm comprising:
a first end and a second end;
a shank extending between the first end and the second end and having a first face and a second face;
a first hole in the shank proximate the first end;
a second hole in the shank proximate the second end; and
a transverse groove in the first face intersecting the second hole and having:
a base;
a first open end and a second open end; and
a first side face and a second side face,
wherein:
the transverse groove first side face and second side face converge toward each other from the first open end to the second open end;
an average depth of the transverse groove is at least 2.0 mm;
a distance between centers of the first and second holes is 25 millimeters to 51 millimeters; and
an overall length of the vane arm is no more than 80 millimeters.
2 . The vane arm of claim 1 wherein:
the transverse groove first side face and second side face converge toward each other from the first open end to the second open end at an angle (θ) of 15° to 35° over at least 50% of a length of the transverse groove.
3 . The vane arm of claim 2 wherein:
the angle is 20° to 30° over at least 50% of the length of the transverse groove.
4 . The vane arm of claim 1 wherein:
the transverse groove first side face and second side face diverge from each other a direction from the base to the first face at an angle (γ) of 40° to 60° over at least 50% of the length of the transverse groove and at least 50% of the depth of the transverse groove.
5 . The vane arm of claim 1 wherein:
the transverse groove first side face and second side face are, over a majority of their respective areas, planar facets.
6 . The vane arm of claim 1 further comprising:
a third hole between the first hole and the second hole and closer to the second hole.
7 . The vane arm of claim 1 being machined from a nickel-alloy.
8 . A vane assembly including the vane arm of claim 1 and further comprising a vane having an airfoil and a shaft protruding from an end of the airfoil, wherein:
the vane shaft extends through the second hole;
the vane shaft has first and second faces respectively abutting the transverse groove first side face and second side face; and
a nut holds the vane arm to the shaft.
9 . The vane assembly of claim 8 , wherein:
the vane shaft first and second faces and the transverse groove first side face and second side face are configured to prevent assembly with the vane arm in an orientation 180° about an axis of the shaft.
10 . The vane assembly of claim 9 further comprising:
a pin mounted in and protruding from the first hole.
11 . A vane stage comprising a plurality of vane assemblies of claim 8 , and further comprising:
a synchronizing ring coupled to the vane arms and having an axis; and
for each vane assembly one or more bearings mounting the vane for rotation about an axis of the vane wherein, rotation of the synchronizing ring about its axis rotates the vanes about their respective axes.
12 . A method for using the vane arm of claim 1 , the method comprising:
installing the arm to a vane so that:
a shaft of the vane extending from an end of an airfoil of the vane passes through the second hole; and
installing a nut to a threaded portion of the shaft to hold the vane arm to the shaft compressed between the nut and a shoulder of the shaft.
13 . The method of claim 12 further comprising:
installing a pin to the first hole.
14 . The method of claim 12 wherein:
the method is performed with a plurality of vane arms and the respective pins are mounted to a shared synchronizing ring.
15 . A vane assembly comprising:
a vane having an airfoil and a shaft protruding from an end of the airfoil, the shaft having:
a threaded portion;
a shoulder; and
a first facet and a second facet between the shoulder and the threaded portion;
a vane arm having:
a first end and a second end;
a shank extending between the first end and the second end and having a first face and a second face;
a first hole in the shank proximate the first end;
a second hole in the shank proximate the second end, the shaft in the second hole;
a transverse groove intersecting the second hole and having:
a base;
a first sidewall contacting the first facet; and
a second sidewall contacting the second facet; and
a nut holding the vane arm to the shaft compressed between the nut and the shoulder,
wherein:
in cross-section normal to an axis of the threads of the threaded portion, the first and second facets are off-parallel to each other by an angle (θ) of 15° to 35°.
16 . The vane assembly of claim 15 wherein:
the groove is transverse to said axis of the threads of the threaded portion; and
a tab washer is between the nut and the vane arm and has a tab received in a third hole between the first hole and the second hole.
17 . The vane assembly of claim 15 wherein:
the vane arm has a first side face and a second side face;
the first side face and the second side face are opposite from each other about the axis of the threads of the threaded portion; and
the transverse groove has respective open ends at the first side face and second side face.
18 . A vane arm comprising:
a first end and a second end;
a shank extending between the first end and the second end and having a first face and a second face;
a first hole in the shank proximate the first end;
a second hole in the shank proximate the second end; and
a transverse groove in the first face intersecting the second hole and having:
a base;
a first open end and a second open end; and
a first side face and a second side face,
wherein:
the transverse groove first side face and second side face converge toward each other from the first open end to the second open end; and
the transverse groove first side face and second side face converge toward each other from the first open end to the second open end at an angle (θ) of 15° to 35° over at least 50% of a length of the transverse groove.
19 . A vane assembly including the vane arm of claim 18 and further comprising a vane having an airfoil and a shaft protruding from an end of the airfoil, wherein:
the vane shaft extends through the second hole;
the vane shaft has first and second faces respectively abutting the transverse groove first side face and second side face; and
a nut holds the vane arm to the shaft.
20 . A vane stage comprising a plurality of vane assemblies of claim 19 , and further comprising:
a synchronizing ring coupled to the vane arms and having an axis; and
for each vane assembly one or more bearings mounting the vane for rotation about an axis of the vane wherein, rotation of the synchronizing ring about its axis rotates the vanes about their respective axes.