Patent Publication Number: US-9404384-B2

Title: Gas turbine engine synchronizing ring with multi-axis joint

Description:
BACKGROUND 
     The present invention is related to gas turbine engines, and in particular to a system for positioning variable vanes of gas turbine engines. 
     Gas turbine engines rely on rotating and stationary components to effectively and efficiently control the flow of air through the engine. Rotating components include rotor blades employed in compressor and turbine sections for compressing air and extracting energy from air after combustion. Stationary components include vanes placed in the airflow to aid in directing the airflow. By varying the orientation of the vanes (i.e., pivoting them to vary the profile provided to the airflow), airflow characteristics can be optimized for various operating conditions. 
     One system for providing actuation of the vanes is an actuator connected to the plurality of variable vanes via a series of linkages including synchronizing rings and vane arms. Current vane arm and synchronizing ring designs create a bending and twisting moment on the vane arm when the synchronizing ring rotates to vary the orientation of the vanes. This loading condition is caused by over constraint between a vane arm pin and a bushing in which the pin is disposed. This over constrained loading condition occurs on multiple vanes in multiple stages, and creates a large reaction load against movement of the synchronizing ring. Thus, the actuator is required to work harder to overcome the reaction load. Additionally, the loading condition also contributes to inaccuracy with regard to the orienting of the variable vanes, which has a negative impact on engine performance. 
     SUMMARY 
     An assembly includes a synchronizing ring, a vane arm, and a multi-axis joint. The multi-axis joint connects the synchronizing ring to the vane arm and provides the vane arm with movement about a first pivot axis and a second pivot axis. 
     A kit includes a synchronizing ring, a vane arm and a multi-axis joint. The multi-axis joint adapted to be disposed in and extend from the synchronizing ring to connect the vane arm to the synchronizing ring. 
     A gas turbine engine includes an engine case, a compressor and/or turbine section, a synchronizing ring, a plurality of vane arms and a plurality of multi-axis joints. The compressor and/or turbine section has at least a first stage of variable vanes circumferentially spaced radially inward of the engine case. The synchronizing ring is disposed about the engine case. The vane arms are connected to the variable vanes. The plurality of multi-axis joints connect the synchronizing ring to the vane arms and each multi-axis joint provides each vane arm with movement about a first pivot axis and a second pivot axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a gas turbine engine according to an embodiment of the present invention. 
         FIG. 2  is a perspective view of one embodiment of a gas turbine engine case with an assembly of synchronizing rings and vane arms. 
         FIG. 3  is a perspective view with a cross-section of one embodiment of a synchronizing ring, vane arm, and a variable vane. 
         FIG. 4A  is a perspective view of a first trunnion. 
         FIG. 4B  is perspective view with a cross-section of the synchronizing ring, variable vane, vane arm, and the first trunnion of  FIG. 4A . 
         FIG. 5A  is a perspective view of one embodiment of the synchronizing ring. 
         FIG. 5B  is a perspective view of the synchronizing ring of  FIG. 5A  with a cover plate and the first trunnion installed. 
         FIG. 6  is a perspective view of a second embodiment of a synchronizing ring including a cover plate and first trunnion. 
     
    
    
     DETAILED DESCRIPTION 
     The present application discloses a joint feature that allows a vane arm to be actuated by synchronizing ring with reduced bending/twisting moment on the vane arm. In particular, the joint feature introduces an additional degree of freedom into the system by allowing the vane arm to pivot about a second rotational axis relative to the synchronizing ring. As a result of introducing the joint feature, the size and weight of an actuator required to move the synchronizing ring can be reduced. Additionally, introducing the first trunnion improves positioning accuracy of the variable vanes, which has a positive impact to engine performance. 
       FIG. 1  is a representative illustration of a gas turbine engine  10  including a synchronizing ring assembly of the present invention. The view in  FIG. 1  is a longitudinal sectional view along an engine center line.  FIG. 1  shows gas turbine engine  10  including a fan blade  12 , a compressor  14 , a combustor  16 , a turbine  18 , a high-pressure rotor  20 , a low-pressure rotor  22 , and an engine casing  24 . Compressor  14  and turbine  18  include rotor stages  26  and stator stages  28 . 
     As illustrated in  FIG. 1 , fan blade  12  extends from fan hub, which is positioned along engine center line C L  near a forward end of gas turbine engine  10 . Compressor  14  is disposed aft of fan blade  12  along engine center line C L , followed by combustor  16 . Turbine  18  is located adjacent combustor  16 , opposite compressor  14 . High-pressure rotor  20  and low-pressure rotor  22  are mounted for rotation about engine center line C L . High-pressure rotor  20  connects a high-pressure section of turbine  18  to compressor  14 . Low-pressure rotor  22  connects a low-pressure section of turbine  18  to fan blade  12  and a high-pressure section of compressor  14 . Rotor stages  26  and stator stages  28  are arranged throughout compressor  14  and turbine  18  in alternating rows. Thus, rotor stages  26  connect to high-pressure rotor  20  and low-pressure rotor  22 . Engine casing  24  surrounds turbine engine  10  providing structural support for compressor  14 , combustor  16 , and turbine  18 , as well as containment for air flow through engine  10 . 
     In operation, air flow F enters compressor  14  after passing between fan blades  12 . Air flow F is compressed by the rotation of compressor  14  driven by high-pressure turbine  18 . The compressed air from compressor  14  is divided, with a portion going to combustor  16 , a portion bypasses through fan  12 , and a portion employed for cooling components, buffering, and other purposes. Compressed air and fuel are mixed and ignited in combustor  16  to produce high-temperature, high-pressure combustion gases Fp. Combustion gases Fp exit combustor  16  into turbine section  18 . 
     Stator stages  28  properly align the flow of air flow F and combustion gases Fp for an efficient attack angle on subsequent rotor stages  26 . The flow of combustion gases Fp past rotor stages  26  drives rotation of both low-pressure rotor  20  and high-pressure rotor  22 . High-pressure rotor  20  drives a high-pressure portion of compressor  14 , as noted above, and low-pressure rotor  22  drives fan blades  12  to produce thrust Fs from gas turbine engine  10 . 
     Although embodiments of the present invention are illustrated for a turbofan gas turbine engine for aviation use, it is understood that the present invention applies to other aviation gas turbine engines and to industrial gas turbine engines as well. 
       FIG. 2  shows an exemplary portion of engine case  24  surrounding compressor  14 . In addition to casing  24 ,  FIG. 2  illustrates four stator stages  28 . Each stator stage  28  includes a corresponding synchronizing ring  30  and vane arm assembly  32 . 
     Although only one stage of variable vanes V is illustrated in  FIG. 2 , compressor  14  has multiple stages  28  of variable vanes. Each stage of variable vanes is connected to one synchronizing ring  30  via a plurality of vane arm assemblies  32 . Synchronizing rings  30  are movably disposed about the exterior of casing  24 . 
     Each vane arm assembly  32  is connected to a synchronizing ring  30  and is additionally connected to a variable vane V. More particularly, each vane arm assembly  32  is bolted or otherwise connected to a trunnion portion ( FIG. 3 ) of each variable vane which protrudes from casing  24 . As discussed previously, during operation synchronizing rings  30  are rotated relative to casing  24  by an actuator and linkage system (not shown) in order to vary the angular orientation of variable vanes V within gas turbine engine  10 . Variable vanes V can be used in multiple locations including the high pressure compressor (HPC) as well as the low pressure compressor (LPC) sections of gas turbine engine  10 . 
       FIG. 3  shows one stator stage  28  of variable vanes V with casing  24  ( FIGS. 1 and 2 ) removed. Each variable vane V includes a vane trunnion  29 . In addition to synchronizing ring  30 , each vane arm assembly  32  includes a fastener  34 , a vane arm main body  36 , a multiaxis joint feature  37  and a bushing  40 . The multi-axis joint feature  37  includes a first trunnion  38  and a second trunnion  42 . Synchronizing ring  30  includes a main body  44  and a cover plate  46 . 
     Each vane arm assembly  32  connects synchronizing ring  30  to each variable vane V. At a first end of vane arm assembly  32 , fastener  34  connects vane arm main body  36  to an outer radial portion of vane trunnion  29 . At a second end of vane arm assembly  32 , vane arm main body  36  is pivotally connected to synchronizing ring  30 . In particular, first trunnion  38  is disposed within synchronizing ring  30  and comprises a rotatable feature about which vane arm  5  main body  36  can pivot relative to synchronizing ring  30 . Bushing  40  is disposed adjacent first trunnion  38  and is disposed around second trunnion  42 . Bushing  40  extends between first trunnion  38  and vane arm main body  36 . Second trunnion  42  comprises a rotatable pin about which vane arm main body  36  can pivot relative to synchronizing ring  30 . Thus, first trunnion  38  and second trunnion  42  allow vane arm main body  36  to pivot about two intersecting rotational axes relative to the synchronizing ring  30 . 
     As shown in  FIG. 3 , second trunnion  42  comprises a pin that is received in a central portion of first trunnion  38 . Second trunnion  42  extends from first trunnion  38  and main body  44  to connect to vane arm main body  36 . Cover plate  46  is disposed on an aft surface of synchronizing ring  30 . Cover plate  46  encloses and holds first trunnion  38  within the remainder of synchronizing ring  30 . 
     Multi-axis joint  37  serves as a component that connects vane arm main body  36  to synchronizing ring  30 . During operation when synchronizing ring  30  moves circumferentially about a rotational axis relative to casing  24  ( FIGS. 1 and 2 ), the movement of synchronizing ring  30  circumferentially translates and rotates vane arm main body  36  pivotally around second trunnion  42 . Additionally, first trunnion  38  pivots and self aligns with second trunnion  42 , which results in binding free movement of vane arm main body  36 . This [[is]] binding free movement is achieved because first trunnion  38  creates an additional degree of freedom in the assembly, thus reducing or eliminating the mechanical constraints induced by the positioning change of the synchronizing ring  30  relative to the variable vane V. Thus, first trunnion  38  allows second trunnion  42  to pivot freely without inducing preload or moment to vane arm main body  36 . 
       FIGS. 4A and 4B  show first trunnion  38 . In particular,  FIG. 4A  shows first trunnion  38  includes a central hole  48  therein.  FIG. 4B  shows a cross-sectional view of synchronizing ring  30  and vane arm assembly  32 . As previously discussed, vane arm assembly  32  includes fastener  34 , vane arm main body  36 , bushing  40 , and second trunnion  42 . Synchronizing ring  30  includes main body  44  and cover plate  46 . In the illustrated embodiment the main body  44  includes first flange F 1 , second flange F 2  and web W. 
     As shown in  FIGS. 4A and 4B , central hole  48  that extends through a central circumferential surface of first trunnion  38 . The central hole  48  receives second trunnion  42  therein. As shown in  FIG. 4B , second trunnion  42  extends from first trunnion  38  and synchronizing ring  30  to connect to, and provide a trunnion pin for, vane arm main body  36 . 
       FIG. 4B  illustrates the rotational axis A 1  of first trunnion  38 . The rotational axis A 2  of second trunnion  42  intersects with the rotational axis A 1  of first trunnion  38 . Because synchronizing ring  30  is movable about a rotational axis relative to casing  24  ( FIGS. 1 and 2 ), the first trunnion  38  pivots about rotational axis A 1 , and the second trunnion  42  pivots about rotational axis A 2 , the assembly has multiple degrees of freedom allowing for binding free movement of vane arm main body  36 . 
       FIGS. 5A and 5B  show the embodiment of synchronizing ring  30  from  FIGS. 3 and 4B .  FIG. 5A  shows synchronizing ring  30  with cover plate  46  removed. Synchronizing ring  30  includes main body  44 , a cavity  50 , and channels  52 A and  52 B.  FIG. 5B  illustrates synchronizing ring  30  with cover plate  46  and first trunnion  38  installed. 
     In the embodiment of synchronizing ring  30  shown in  FIGS. 5A and 5B , synchronizing ring  30  has an I-beam cross-sectional shape with channels  52 A and  52 B in opposing surfaces of main body  44 . In other embodiments, synchronizing ring  30  can have any cross-sectional shape including a square, round, or rectangular shape. Cavity  50  extends through the central portion of main body  44  and is open to channels  52 A and  52 B on either side. Cavity  50  is a counter-bore feature open at one end and is adapted to receive first trunnion  38  therein. Thus, when installed portions of first trunnion  38  interface with channels  52 A and  52 B. As shown in  FIG. 5B , cover plate  46  can be connected to main body  44  by fasteners  54 . Cover plate  46  holds first trunnion  38  within synchronizing ring  30 . 
       FIG. 6  shows a second embodiment of synchronizing ring  130  which is similar to synchronizing ring  30  ( FIGS. 2, 3, and 4B ) but includes a different connection to hold a cover plate  146  to synchronizing ring  130 . As illustrated in  FIG. 6 , synchronizing ring  130  includes a main body  144 , cover plate  146 , channels  152 A and  152 B, and grooves  156 . In the illustrated embodiment the main body  144  includes first flange F 1 ′, second flange F 2 ′ and web W′.  FIG. 5B  additionally illustrates an embodiment of first trunnion  138  installed in synchronizing ring  130 . 
     Similar to the embodiment of synchronizing ring  30  shown in  FIGS. 5A and 5B , synchronizing ring  130  of  FIG. 6  has an I-beam cross-sectional shape with channels  152 A and  152 B in opposing surfaces of main body  144 . When installed, portions of first trunnion  138  interface with channels  152 A and  152 B. As shown in  FIG. 6 , cover plate  146  is retained to main body  144  by grooves  156 . Grooves  156  allow cover plate  146  to be installed in and retained in main body  144 . Cover plate  146  holds first trunnion  138  within synchronizing ring  130 A. 
     The present application discloses a joint feature that allows a vane arm to be actuated by synchronizing ring with reduced bending/twisting moment on the vane arm. In particular, the joint feature introduces an additional degree of freedom into the system by allowing the vane arm to pivot about a second rotational axis relative to the synchronizing ring. As a result of introducing the joint feature, the size and weight of an actuator required to move the synchronizing ring can be reduced. Additionally, introducing the first trunnion improves positioning accuracy of the variable vanes, which has a positive impact to engine performance. 
     Discussion of Possible Embodiments 
     The following are non-exclusive descriptions of possible embodiments of the present invention. 
     An assembly includes a synchronizing ring, a vane arm, and a multi-axis joint. The multi-axis joint connects the synchronizing ring to the vane arm and provides the vane arm with movement about a first pivot axis and a second pivot axis. 
     The assembly of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components: 
     the multi-axis joint has a first trunnion that is held within the synchronizing ring by a cover plate; 
     the cover plate is retained to the synchronizing ring by at least one of a fastener and/or grooves; 
     the synchronizing ring has an I-beam cross-sectional shape; 
     the multi-axis pivot joint has a first trunnion and a second trunnion, and wherein the synchronizing ring is movable about an axis, the first trunnion rotates about the first pivot axis, and the second trunnion rotates about the second pivot axis; 
     the multi-axis joint has a second trunnion that comprises a pin, and wherein the first trunnion has a hole that receives the pin therein; 
     wherein the multi-axis joint has a first trunnion that defines the first pivot axis and a second trunnion that defines the second pivot axis, and wherein the first pivot axis intersects with the second pivot axis; and 
     the first pivot axis is perpendicular to the second pivot axis. 
     A kit includes a synchronizing ring, a vane arm and a multi-axis joint. The multi-axis joint adapted to be disposed in and extend from the synchronizing ring to connect the vane arm to the synchronizing ring. 
     The kit of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components: 
     the kit includes a cover plate adapted to hold the multi-axis joint within the synchronizing ring; 
     the cover plate is retained to the synchronizing ring by at least one of a fastener and/or grooves; 
     the synchronizing ring has an I-beam cross-sectional shape; and 
     wherein the multi-axis joint provides the vane arm with movement about a first pivot axis and a second pivot axis, and wherein the multi-axis joint has a first trunnion and a second trunnion. 
     A gas turbine engine includes an engine case, a compressor and/or turbine section, a synchronizing ring, a plurality of vane arms and a plurality of multi-axis joints. The compressor and/or turbine section has at least a first stage of variable vanes circumferentially spaced radially inward of the engine case. The synchronizing ring is disposed about the engine case. The vane arms are connected to the variable vanes. The plurality of multi-axis joints connect the synchronizing ring to the vane arms and each multi-axis joint provides each vane arm with movement about a first pivot axis and a second pivot axis. 
     The gas turbine engine of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components: 
     the multi-axis joint has a first trunnion that is held within the synchronizing ring by a cover plate; 
     the cover plate is retained to the synchronizing ring by at least one of a fastener and/or grooves; 
     the synchronizing ring has an I-beam cross-sectional shape; 
     the multi-axis pivot joint has a first trunnion and a second trunnion, and wherein the synchronizing ring is movable about an axis, the first trunnion rotates about the first pivot axis, and the second trunnion rotates about the second pivot axis; 
     the multi-axis joint has a second trunnion that comprises a pin, and wherein the first trunnion has a hole that receives the pin therein; 
     the multi-axis joint has a first trunnion that defines the first pivot axis and a second trunnion that defines the second pivot axis, and wherein the first pivot axis intersects with the second pivot axis; 
     the multi-axis joint has a first trunnion that defines the first pivot axis and a second trunnion that defines the second pivot axis, and wherein the first pivot axis intersects with the second pivot axis; and 
     the first pivot axis is perpendicular to the second pivot axis. 
     While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.