This application relates to a bearing retainer that prevents undesired rotation of the actuator for a variable vane system.
Gas turbine engines are known, and typically include a fan delivering air into a compressor section. The air is compressed in the compressor section, and delivered downstream into a combustion section where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors, driving them to rotate.
The compressor section typically includes a plurality of compressor stages having rotors carrying a plurality of rotating blades. Intermediate the compressor stages are static vanes, which serve to redirect the airflow between the compressor stages.
A desired approach angle for the air may vary during operation of the gas turbine engine, and dependent upon operational conditions. Thus, it is known to provide so-called variable vanes which are pivotably mounted such that their angle can be changed. Typically, a single actuator drives a ring to rotate, and this rotation causes the orientation of a plurality of vanes to be changed.
One known actuator includes a piston rod of a cylinder to cause the rotation of a bell crank. The cylinder is mounted at a rear end on a spherical bearing, and the piston is also mounted on a spherical bearing within a clevis.
The use of the spherical bearings allows some misalignment such as may be due to manufacturing tolerances or thermal displacement.
However, when stresses and force are placed on the actuator, and in particular the piston rod, the cylinder may rotate about its own axis. When this occurs, the cylinder or its mount structure may strike a mount structure associated with a housing. This is undesirable.
In a featured embodiment, a variable vane actuator has a plurality of vanes which may be rotated to change an approach angle of associated airfoils. A cylinder is mounted to drive a piston rod to in turn cause a linkage system to vary the approach angle of the airfoils. The cylinder has a tailstock at an end remote from the piston rod. The tailstock is pivotably mounted within a clevis, and on a bolt. A spherical bearing is between the bolt and tailstock, and includes an inner member riding on the bolt and having a spherical outer surface, and an outer member which moves with the tailstock, and a spherical inner surface moveable on the spherical outer surface of the inner member. The clevis includes two spaced ledges. A bearing retainer is between one of the ledges and the spherical bearing. The bearing retainer is formed of a material that is softer than a material forming the tailstock such that the bearing retainer provides a stop to prevent undue rotation of the tailstock and the outer member relative to the inner member.
In another embodiment according to the previous embodiment, the bearing retainer has a shape of a top hat, with an extension extending from a planer section. The planer section abuts the spherical bearing. The extension fits within an opening in one of the ledges. The bolt extends through the extension, through the planer portion, through the inner member, and then through a second of the ledges.
In another embodiment according to any of the previous embodiments, the bearing retainer is generally cylindrical.
In another embodiment according to any of the previous embodiments, the bearing retainer has a truncated portion associated with a limited circumferential extent of the bearing retainer. The truncated portion is positioned adjacent an under surface of the cylinder from which the tailstock extends.
In another embodiment according to any of the previous embodiments, the bearing retainer is formed of one of a composite or metal.
In another embodiment according to any of the previous embodiments, a first gap is defined between the bearing retainer and tailstock, and a second gap is defined between a second of the ledges and tailstock. The first gap is smaller than the second gap.
In another embodiment according to any of the previous embodiments, one of the ledges receives a head of the bolt.
In another featured embodiment, a compressor section has a plurality of compressor stages spaced for rotation about a central axis. A plurality of vanes is positioned between adjacent ones of the plurality of compressor stages, with the plurality of vanes provided with an airfoil for directing air to a downstream compressor stage. An approach angle of the plurality of airfoils is changeable by an actuator. The actuator includes a cylinder mounted to drive a piston rod to in turn cause a linkage system to vary the approach angle of the airfoils. The cylinder has a tailstock at an end remote from the piston rod, with the tailstock being pivotably mounted within a clevis, and on a bolt. A spherical bearing is between the bolt and tailstock, with the spherical bearing including an inner member riding on the bolt and having a spherical outer surface. An outer bearing member moves with the tailstock, and has a spherical inner surface moveable on the spherical outer surface of the inner member. The clevis includes two spaced ledges. A bearing retainer is between one of the ledges and the spherical bearing and tailstock. The bearing retainer is formed of a material that is softer than a material forming the tailstock such that the bearing retainer provides a stop to prevent undue rotation of the tailstock and the outer member relative to the inner member.
In another embodiment according to the previous embodiment, the bearing retainer has a shape of a top hat, with an extension extending from a planer section. The planer section abuts the spherical bearing. The extension fits within an opening in one of the ledges, with the bolt extending through the extension, through the planer portion, through the inner member, and then through a second of the ledges.
In another embodiment according to any of the previous embodiments, the bearing retainer is generally cylindrical.
In another embodiment according to any of the previous embodiments, the bearing retainer has a truncated portion associated with a limited circumferential extent of the bearing retainer, with the truncated portion positioned adjacent an under surface of the cylinder from which the tailstock extends.
In another embodiment according to any of the previous embodiments, the bearing retainer is formed of one of a composite or metal.
In another embodiment according to any of the previous embodiments, a first gap is defined between the bearing retainer and tailstock, and a second gap is defined between a second of the ledges and tailstock. The first gap is smaller than the second gap.
In another embodiment according to any of the previous embodiments, one of the ledges receives a head of the bolt.
In another featured embodiment, a gas turbine engine has a compressor section, a combustor, and a turbine section. The compressor section includes a plurality of compressor stages spaced for rotation about a central axis. A plurality of vanes is positioned between adjacent ones of the plurality of compressor stages, with the plurality of vanes being provided with an airfoil for directing air to a downstream compressor stage. An approach angle of the plurality of airfoils is changeable by an actuator. The actuator includes a cylinder mounted to drive a piston rod to in turn cause an actuator to vary the approach angle of the airfoils. The cylinder has a tailstock at an end remote from the piston rod. The tailstock is pivotably mounted within a clevis, and on a bolt. A spherical bearing is between the bolt and tailstock, and includes an inner member riding on the bolt and having a spherical outer surface, and an outer bearing member which moves with the tailstock. A spherical inner surface is moveable on the spherical outer surface of the inner member. The clevis includes two spaced ledges. A bearing retainer is between one of the ledges and the spherical bearing and tailstock. The bearing retainer is formed of a material that is softer than a material forming the tailstock such that the bearing retainer provides a stop to prevent undue rotation of the tailstock and the outer member relative to the inner member and the bolt.
In another embodiment according to any of the previous embodiments, the bearing retainer has a shape of a top hat, with an extension extending from a planer section. The planer section abuts the spherical bearing. The extension fits within an opening in one of the ledges, with the bolt extending through the extension through the planer portion, through the inner member, and then through a second of the ledges.
In another embodiment according to any of the previous embodiments, the bearing retainer is generally cylindrical.
In another embodiment according to any of the previous embodiments, the bearing retainer has a truncated portion associated with a limited circumferential extent of the bearing retainer. The truncated portion is positioned adjacent an under surface of the cylinder from which the tailstock extends.
In another embodiment according to any of the previous embodiments, a first gap is defined between the bearing retainer and tailstock, and a second gap is defined between a second of the ledges and the tailstock. The first gap is smaller than the second gap.
In another embodiment according to any of the previous embodiments, one of the ledges receives a head of the bolt.
These and other features of this application will be best understood from the following specification and drawings, the following of which is a brief description.
The engine 20 generally includes a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine static structure 36 via several bearing systems 38. It should be understood that various bearing systems 38 at various locations may alternatively or additionally be provided.
The low speed spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor 44 and a low pressure turbine 46. The inner shaft 40 is connected to the fan 42 through a geared architecture 48 to drive the fan 42 at a lower speed than the low speed spool 30. The high speed spool 32 includes an outer shaft 50 that interconnects a high pressure compressor 52 and high pressure turbine 54. A combustor 56 is arranged between the high pressure compressor 52 and the high pressure turbine 54. A mid-turbine frame 57 of the engine static structure 36 is arranged generally between the high pressure turbine 54 and the low pressure turbine 46. The mid-turbine frame 57 further supports bearing systems 38 in the turbine section 28. The inner shaft 40 and the outer shaft 50 are concentric and rotate via bearing systems 38 about the engine central longitudinal axis A which is collinear with their longitudinal axes.
The core airflow is compressed by the low pressure compressor 44 then the high pressure compressor 52, mixed and burned with fuel in the combustor 56, then expanded over the high pressure turbine 54 and low pressure turbine 46. The mid-turbine frame 57 includes airfoils 59 which are in the core airflow path. The turbines 46, 54 rotationally drive the respective low speed spool 30 and high speed spool 32 in response to the expansion.
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Additional turbine stages 428 may be driven by products of the combustion to in turn drive a generator 430. Engine 420 is an industrial gas turbine, such as may be utilized in land-based applications to generate electricity. The features of this application would apply to this type engine as well.
This application relates to improvements in a tailstock mount, which mounts a tailstock 82 associated with the cylinder 80 in a clevis 84 on a static housing. As shown, a bolt 86 mounts the tailstock 82 in the clevis 84.
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The retainer 110 is formed of a composite or metal such as aluminium or steel. Generally, the retainer 110 should be formed of a softer material than the material used for the actuator tailstock, or the bearing outer surface 102. Thus should there be damage due to the rotation, it will be the less expensive retainer 110 which is damaged.
While an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.