Patent Publication Number: US-11649734-B1

Title: Variable guide vane control system

Description:
TECHNICAL FIELD 
     The disclosure relates generally to variable guide vanes and, more particularly, to variable guide vane control systems. 
     BACKGROUND 
     Turbine engines sometimes have variable guide vanes (VGVs) disposed in an inlet section, a compressor section or a turbine section. An angular orientation of the guide vanes are adjustable relative to a gas path in order to control the flow being directed through the gas path. An actuator positioned outside the gas path is conventionally used to actuate adjustment of the angular orientation of the VGVs. Control of the angular orientation of the VGVs remains a challenge. 
     SUMMARY 
     In accordance with a general aspect, there is provided a variable guide vane control system for a turbine engine having at least one vane rotatable about a vane axis, the system comprising: an actuator; and a rolling contact joint including: a drive ring rotatable about a drive axis and rotatably coupled to the actuator, at least one roller rotatable about a roller axis parallel to the drive axis and drivingly connectable to the at least one vane, and a first flexible member and a second flexible member tethering the drive ring and the at least one roller to one another, the first flexible member and the second flexible member respectively tensioned when the drive ring rotates about the drive axis in a first direction and in a second direction opposite the first direction. 
     In accordance with another aspect, there is provided a turbine engine comprising: a duct defining a gas path; at least one vane rotatably connected relative to the duct so as to extend in the gas path and be rotatable about a vane axis between a first vane position and a second vane position relative to the gas path; an actuator; and a rolling contact joint including: a drive ring rotatable about a drive axis and rotatably coupled to the actuator, at least one roller rotatable about a roller axis parallel to the drive axis and drivingly connected to the at least one vane, and a first flexible member and a second flexible member tethering the drive ring and the at least one roller to one another, the first flexible member and the second flexible member respectively tensioned when the drive ring rotates about the drive axis in a first direction and in a second direction opposite the first direction. 
     In accordance with a still further general aspect, there is provided a method of controlling rotation of at least one vane about a vane axis, the method comprising: rotating a drive ring about a drive axis; transmitting a rotation of the drive ring to at least one roller radially outward of the drive ring and rotatable about a roller axis parallel to the drive axis to rotate the at least one roller about the roller axis; transmitting a rotation of the at least one roller to the at least one vane to rotate the at least one vane about the vane axis; and opposing backlash between the transmitting the rotation of the drive ring to the at least one roller and the transmitting rotation of the at least one roller to the at least one vane. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is now made to the accompanying figures in which: 
         FIG.  1    is a schematic cross-sectional view of a turbine engine having a variable guide vane control system; 
         FIG.  2    is a perspective view of portions of the variable guide vane control system according to an embodiment; 
         FIG.  3    is a perspective view of portions of the variable guide vane control system of  FIG.  2   , shown in a first position; 
         FIG.  4    is a perspective view of portions of the variable guide vane control system of  FIG.  2   , shown in a second position; 
         FIG.  5    is a close-up view of portions of the variable guide vane control system of  FIG.  2   ; 
         FIG.  6    is a close-up view of the portions of the variable guide vane control system of  FIG.  5   , an outer roller portion and an outer ribbon or flexible member thereof having been removed; 
         FIG.  7    is an elevation view of portions of the variable guide vane control system of  FIG.  2   ; 
         FIG.  8    is a perspective view of an inner portion of a variable guide vane control system according to another embodiment; and 
         FIG.  9    is a perspective view of an outer portion of the variable guide vane control system of  FIG.  8   . 
     
    
    
     DETAILED DESCRIPTION 
     The terms “attached”, “coupled”, “connected”, “engaged”, “mounted” and other like terms as used herein may include both direct attachment, coupling, connection, engagement or mounting (in which two components contact each other) and indirect attachment, coupling, connection, engagement or mounting (in which at least one additional component is located between the two components). 
     The term “generally” and other like terms as used herein may be applied to modify any quantitative representation which could permissibly vary without resulting in a change in the basic function to which it is related. 
     Aspects of various embodiments will now be described through reference to the drawings. 
       FIG.  1    illustrates a turbine engine  10  which may for example be part of an aircraft. Depending on the implementation of the present technology, the engine  10  could be any type of turbine engine including but not limited to a turbojet engine, a turbofan engine, a turboprop engine, and a turboshaft engine. In the illustrated example, the engine  10  is of the turboshaft type and generally comprises in serial flow communication an inlet section  12  for receiving air, a compressor section  14  for pressurizing the air, a combustor  16  in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section  18  for extracting energy from the combustion gases. A flow path  20  of the engine  10  is defined by respective inner  20 A and outer  20 B walls of the inlet section  12 , the compressor section  14  and the turbine section  18 . The engine  10  may be provided with one or more arrays of variable guide vanes (VGVs, or vanes)  30  to locally regulate the fluid flow in the flow path  20 . An array of vanes  30  corresponds to a plurality of vanes  30  circumferentially spaced apart from one another at a given axial location relative to a central axis A E  of the engine  10 . In the illustrated example, one such array of vanes  30  is provided in the inlet section  12 . The vanes  30  in this case may thus be referred to as variable inlet guide vanes (or VIGVs). Each vane  30  of a given array of vanes  30  extends across the flow path  20  and is rotatably connected relative to at least one of the inner and outer walls  20 A,  20 B about a respective vane axis A V  so as to be orientable relative to the flow path  20 . Rotation of each vane  30  of the array of vanes  30  about its respective vane axis A V  is governed by a variable guide vane control system  40  (hereinafter “control system”  40 ) generally comprising an actuator  40 A and rolling contact joints  40 B operatively connecting the actuator  40 A to the vanes  30  of a given array. Further details pertaining to the control system  40  will be provided hereinbelow. 
     Although the embodiment depicted in  FIG.  1    shows that the engine  10  has a sole array of vanes  30  located in the inlet section  12 , it shall be understood that depending on the embodiment, the engine  10  may include one or more arrays of vanes  30 , one or more of which may be located elsewhere in the engine  10 , for example upstream of a rotor of the compressor section  14  or upstream of a rotor of the turbine section  18 . More than one array of vanes  30  may be provided in a given section  12 ,  14 ,  18  of the engine  10 . In embodiments, the inlet section  20  is absent any vanes  30 . The vanes  30  extend spanwise along their respective vane axis A V  in an orientation that is generally transverse relative to a flow orientation of the flow path  20 . Hence, the vane axes A V  may extend spanwise at an angle relative to the central axis A E  that is suitable for the shape and orientation of the flow path  20  at the location of the vanes  30 . In the depicted embodiment, the vanes  30  are located in a portion of the flow path  20  defined by the inlet section  12  that extends generally radially relative to the central axis A E , such that the vane axes A V  are generally parallel to the central axis A E  of the engine  10 . 
     Referring to  FIGS.  2  to  4   , the control system  40  is a means suitable for selectively imparting rotation to the vanes  30  about their respective vane axes A V  so as to position each vane  30  at a desired angular position or angle of attack α relative to a direction of the flow inside the flow path  20 , schematically shown by arrow F. This angle of attack α is defined by a direction in which each vane  30  extends from its leading edge  32  to its trailing edge  34  ( FIG.  2   ) relative to its vane axis A V . In  FIGS.  2  and  3   , the vane  30  is shown in a first angular vane position α v1 , whereas in  FIG.  4   , the vane  30  is shown in a second angular vane position α v2 . The angle of attack α is greater in the first angular vane position α v1  than in the second angular vane position α v2 , i.e., the vane  30  impinges the flow F more in the first angular vane position α v1  than in the second angular vane position α v2 . In embodiments, the first and second vane positions α v1 , α v2  may respectively correspond to closed and open positions of the vane  30  defining opposite boundaries, or maximum and minimum values, of a range of vane positions of the vane  30 . 
     As mentioned hereinabove, the rotation of the vanes  30  is operated by the control system  40 . The actuator  40 A, in this case being of the hydraulic type, may otherwise be configured to be powered by any suitable power source. The actuator  40 A has an end effector that is controllably movable from a first actuator position to a second actuator position, defining a range of actuator positions of the end effector. The rolling contact joints  40 B interconnect the end effector of the actuator  40 A and the vanes  30  such that moving the end effector from the first actuator position to the second actuator position moves the vane  30  from the first vane position α v1  to the second vane position α v2 , and vice versa. 
     The rolling contact joints  40 B share a common rolling element referred to henceforth as a drive ring  50 , and respectively have a discrete rolling element referred to henceforth as a roller  60 . The drive ring  50  and the rollers  60  are respectively rotatable about a drive axis A D  and a roller axis A R  that are parallel to one another. Each one of the rollers  60  is radially outward of the drive ring  50  relative to the drive axis A D . Each roller  60  has an outer roller surface  62  extending circumferentially relative to the corresponding roller axis A R  and circumscribed by an outermost diameter of the roller  60 . The rollers  60  are individually rotatably coupled to the drive ring  50  such that rotating the drive ring  50  about the drive axis A D  rotates all of the rollers  60  about their respective roller axis A R . Stated otherwise, the drive ring  50  is drivingly connected to the rollers  60 . The drive ring  50  is rotatably coupled to the end effector of the actuator  40 A by a suitable means, such that the drive ring  50  is controllably rotatable about the drive axis A D . In the depicted embodiments, the drive axis A D  and the central axis A E  of the engine  10  are colinear, although other arrangements are possible. The drive ring  50  may for example be an annular gear, i.e., a ring having an outer ring surface  52  and an inner ring surface  54  provided with teeth, and the end effector may be a pinion drivingly engaged with the inner ring surface  54 . Each roller  60  is rotatably coupled to a given one of the vanes  30  by a suitable means, such that rotating a given roller  60  about its respective roller axis A R  rotates the corresponding vane  30  about its respective vane axis A V . Rotating the given roller  60  from a first roller position α R1  to a second roller position α R2  about its roller axis A R  rotates the corresponding vane  30  about its vane axis A V  from the first vane position α v1  to the second vane position α v2 , and vice versa. In embodiments, the first and the second roller positions α R1 , α R2  define boundaries of a range of roller positions of the rollers  60 . Rotating the drive ring  50  about the drive axis A D  from a first drive ring position α D1  to a second drive ring position α D2  rotates the given roller  60  about its roller axis A R  from the first roller position α r1  to the second roller position α r1 , and vice versa. In embodiments, the first and the second drive ring positions α D1 , α D2  define boundaries of a range of ring positions of the drive ring  50 . 
     In the depicted embodiments, the rollers  60  are drivingly connected to their respective vanes  30  in a direct manner, i.e., each roller  60  is mounted on a stem  36  of its corresponding vane  30 . The stem  36  extends along the vane axis A V  from inside the flow path  20  to outside thereof, in this case through the outer wall  20 B. A peripheral surface of the stem  36  surrounding the vane axis A V  defines an anti-rotational feature, or shape. The roller  60  has an inner wall surrounding the roller axis A R  defining an opening and having a shape complementary to that of the anti-rotational feature of the stem  36 , such that upon the roller  60  being mounted to the stem  36 , the stem  36  is received by the opening and the anti-rotational feature and the inner wall cooperate so as to hinder rotation of the roller  60  and the stem  36  relative to one another about the roller axis A R  and/or the vane axis A V . Axial movement of the roller  60  with respect to the stem  36  relative to the roller axis A R  may be hindered on either side by the wall  20 A,  20 B through which the stem  36  extends (in this case the outer wall  20 B), and by a fastener  38  or other suitable means disposed at a distal end of the stem  36 . 
     In other embodiments, the rollers  60  may be indirectly drivingly connected to their respective vanes  30 . Each roller  60  may be mounted to, or form part of, a respective input shaft that is rotatably coupled to a corresponding one of the stems  36 , for example by way of suitable gearing. In some such embodiments, the input shafts extend along the roller axes A E , whereas the vane axes A V  may be at an angle relative to their corresponding roller axes A R  and to the central axis A E . Suitable interfaces are provided between corresponding input shafts and stems  36 , which may for example be beveled gears. The vanes  30  may extend spanwise radially relative to the central axis A E , as the case may be for vanes  30  provided in the compressor section  14  or in the turbine section  18 , for example. In such cases, the vanes  30  are rotatably connected to a rotor shroud of the engine  10 . 
     The coupling of the drive ring  50  and the rollers  60  is realized by one or more coupling means of the rolling contact joints  40 B, one of which is provided in the form of flexible members  70 , also referred to as ribbons, bands or compliant members, that tether the rollers  60  to the drive ring  50 . Each one of the rollers  60  is tethered by a plurality of flexible members  70  that includes a first flexible member  70 ′ and a second flexible member  70 ″ that are respectively tensioned at least when the drive ring  50  rotates about the drive axis A D  in a first direction of rotation (or first handedness) R1, and in a second direction of rotation (or second handedness) R2 opposite the first direction R1. 
     Each flexible member  70 , or flexible member, is a strip of material that extends lengthwise between opposite ends respectively held stationary adjacent to a given roller  60  and to the drive ring  50  by a suitable means. Namely, the first flexible member  70 ′ and the second flexible member  70 ″ respectively have first and second ring ends  72 ′,  72 ″ and first and second roller ends  74 ′,  74 ″. Depending on the embodiment, the first and second ring ends  72 ′,  72 ″ are either mechanically attached (e.g., welded, brazed or fastened) to the drive ring  50  ( FIGS.  2 - 7   ) or are integral therewith ( FIGS.  8 - 9   ). Conversely, the first and second roller ends  74 ′,  74 ″ are either mechanically attached to their corresponding roller  60  ( FIGS.  2 - 7   ) or are integral therewith ( FIGS.  8 - 9   ). 
     By this tethered arrangement, rotational slippage of the drive ring  50  relative to the rollers  60 , i.e., an amount of rotation of the drive ring  50  that would not concurrently induce an expected corresponding amount of rotation of one or more of the rollers  60 , is eliminated or rendered negligible by the flexible members  70 . Contrary to typical geared coupling arrangements in which a distance between adjacent land surfaces of meshed teeth results in backlash, i.e., a resulting distance that must be traveled by a driving tooth upon a change of direction of rotation thereof, the control system  40  is effectively backlash free, at least at the interfaces between the drive ring  50  and the rollers  60 . Likewise, by this tethered arrangement, rotational slippage of the rollers  60  relative to the drive ring  50 , which may otherwise occur in presence of airflow-induced vibratory loads on the vanes  30  for example, is eliminated or rendered negligible by the flexible members  70 . 
     Hence, rotating the drive ring  50  about the drive axis A D  in the first direction R1 immediately brings tension (or an increase in tension) in the first flexible member  70 ′ tethered to a given roller  60  and immediately induces rotation of the corresponding vane  30  (in this case rotation toward the second vane position α v2 ). Conversely, rotating the drive ring  50  about the drive axis A D  in the second direction R2 immediately brings tension (or an increase in tension) in the second flexible member  70 ″ tethered to the given roller  60  and immediately induces rotation of the corresponding vane  30  (in this case rotation toward the first vane position α v1 ). Moreover, maintaining the drive ring  50  at a given ring position maintains the vanes  30  respectively at corresponding vane positions. 
     In some embodiments, the first flexible member  70 ′ and the second flexible member  70 ″ remain tensioned regardless of whether the drive ring  50  rotates or not, and regardless of the position the drive ring  50  and the rollers  60  are at within their respective range of positions. This may assist in eliminating any rotational play between the drive ring  50  and the rollers  60  regardless of loading conditions. 
     Each flexible member  70  is constructed so as to be resiliently flexible thicknesswise in order to at least partially wrap around the drive ring  50  or the corresponding roller  60  depending on the direction in which the drive ring  50  rotates. Yet, each flexible member  70  is sufficiently rigid lengthwise such that when placed under tension due to loads originating from the vanes  30  or from the actuator  40 A, any lengthening of the flexible member  70  is negligible. 
     In  FIGS.  2 ,  3 ,  5  and  6   , the drive ring  50  is in the first ring position α D1  and the rollers  60  are in the first roller position am. In this first relative position, the first flexible members  70 ′ are at least partially wrapped around their corresponding rollers  60 , whereas the second flexible members  70 ″ are at least partially wrapped around the drive ring  50 . As best seen in  FIG.  5   , a portion of the first flexible member  70 ′ proximate to the first ring end may be spaced from the roller  60 . This portion may correspond to a length of the first flexible member  70 ′ that is held against the drive ring  50 . Conversely, as best seen in  FIG.  6   , a portion of the second flexible member  70 ″ proximate to the second roller end may be spaced from the drive ring  50 . This portion may correspond to a length of the second flexible member  70 ″ that is held against the roller  60 . In  FIG.  4   , the drive ring  50  is in the second ring position α D2  and the rollers  60  are in the second roller position α R2 . In this second relative position, the second flexible members  70 ″ are at least partially wrapped around their corresponding rollers  60 , whereas the first flexible members  70 ′ are at least partially wrapped around the drive ring  50 . Rotating the drive ring  50  from the first ring position α D1  to the second ring position α D2  causes the first flexible members  70 ′ to unwrap from their corresponding rollers  60  and to wrap around the drive ring  50 , and causes the second flexible members  70 ″ to unwrap from the drive ring  50  and to wrap around their corresponding rollers  60 , and vice versa. 
     In the embodiment depicted in  FIGS.  2 - 7   , the first and second ring ends  72 ′,  72 ″ are held at an outermost diameter of the drive ring  50  adjacent to the outer ring surface  52 , and the first and second roller ends  74 ′,  74 ″ are held at an outermost diameter of the roller  60  adjacent to the outer roller surface  62 . Moreover, as best seen in  FIG.  7   , the flexible members  70  extend thicknesswise radially outwardly relative to the drive axis A D  from the outer ring surface  52  to the outer roller surface  62 . Stated otherwise, a thickness T of the flexible members  70  fills a radial gap defined between the drive ring  50  and the rollers  60 . In such embodiments, the drive ring  50  does not directly engage the rollers  60 , and may be said to be indirectly coupled to the rollers  60  via the flexible members  70 . 
     The outer roller surface  62  is circumscribed by an outer roller circumference C1, and yet in this example extends circumferentially by a circumferential length that is less than the roller circumference C. A remainder, or hub  64 , of the roller  60  is circumscribed by an inner roller circumference C2 that is smaller than the outer roller circumference C1. It should be noted that the circumferential length of the outer roller surface  62  may be equal to or less than a length L of either one of its corresponding flexible members  70 . A free length of the flexible member  70  (i.e., a length of the flexible member  70  that is unattached to the drive ring  50 ) may in some embodiments correspond to the circumferential length of outer surface  62 . The outer roller surface  62  is defined by an arcuate pad  66  that projects radially from the hub  64  relative to the roller axis A R  so as to define a pad thickness P. Various shapes are contemplated for the rollers  60 , so long as the outer roller surface  62  is arcuate. Depending on the implementation, the range of vane positions may be set by providing the rollers  60  with a suitable pad thickness P. For instance, increasing the pad thickness P (and spacing the rollers  60  radially outwardly relative to the drive axis A D  by a corresponding distance) increases an effective radius of the rollers  60 , which decreases the range of vane positions and decreases the rate at which the rollers  60  rotate for each degree of rotation of the drive ring  50 . Decreasing the pad thickness P (and bringing the rollers  60  radially inwardly relative to the drive axis A D  by a corresponding distance) decreases the effective radius, which increases the range of vane positions and increases the rate at which the rollers  60  rotate for each degree of rotation of the drive ring  50 . 
     It is contemplated however that the location at which the flexible members  70  meet the drive ring  50  and the rollers  60  may vary depending on the embodiment. For instance, the flexible members  70  may be recessed relative to the outer ring surface  52  and/or the outer roller surfaces  62 , such that the outer ring surface  52  and the outer roller surfaces  62  may engage one another. Such an arrangement may be referred to as a secondary coupling means of the rolling contact joints  40 B, whereby friction between the outer ring surface  52  and the outer roller surfaces  62  assists in transmitting rotation from the drive ring  50  to the rollers  60 . 
     Referring to  FIGS.  8  and  9   , the drive ring  50  is formed of first and second ring portions  50 ′,  50 ″ respectively having first and second outer ring surfaces  52 ′,  52 ″, and the rollers  60  are respectively formed of first and second roller portions  60 ′,  60 ″ respectively having first and second outer roller surfaces  62 ′,  62 ″. The first ring portion  50 ′, the first flexible members  70 ′ and the first roller portions  60 ′ together form a first integral rolling contact joint  40 B′, whereas the second ring portion  50 ″, the second flexible members  70 ″ and the second roller portions  60 ″ together form a second integral rolling contact joint  40 B″. The first and second integral rolling contact joints  40 B′,  40 B″ are to be mounted side by side, such that the ring portions  50 ′,  50 ″ are paired to be simultaneously driven by the actuator  40 A and corresponding roller portions  60 ′,  60 ″ are paired to simultaneously drive a corresponding vane  30 . It is also contemplated that in some embodiments, an integral rolling contact joint  40 B may be provided, in which a sole drive ring  50  is tethered to unitary rollers  60  by way of integrally-formed flexible members  70 . 
     Among the various suitable manufacturing methods contemplated, additive manufacturing may be used, for example to produce rolling contact joints  40 B having flexible members  70  that are integral to the drive ring(s)  50  and/or to the rollers  60 . 
     All of the above described embodiments provide for a method of controlling rotation of at least one vane about a vane axis, wherein the method comprises: rotating a drive ring about a drive axis; transmitting a rotation of the drive ring to at least one roller radially outward of the drive ring and rotatable about a roller axis parallel to the drive axis to rotate the at least one roller about the roller axis; transmitting a rotation of the at least one roller to the at least one vane to rotate the at least one vane about the vane axis; and opposing backlash between the transmitting the rotation of the drive ring to the at least one roller and the transmitting rotation of the at least one roller to the at least one vane. The opposing of the backlash may include tensioning at least one flexible member tethering the drive ring and the at least one roller to one another. The opposing of the backlash may include maintaining a correspondence between respective orientations of a plurality of vanes including the at least one vane relative to a gas path of an engine. 
     The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology. For example, more than one first flexible member  70 ′ or more than one second flexible member  70 ″ may be provided among the flexible members  70  of a given rolling contact joint  40 B. Flexible members  70  may all have a same width, or may be sized differently. For instance, in an exemplary rolling contact joint  40 B having a sole inner flexible member  70  disposed between two outer flexible members  70  (i.e., a sole second flexible member  70 ″ between two first flexible members  70 ′, or vice versa), the inner flexible member  70  may have a width that is greater than that of the outer flexible members  70 . Yet further modifications could be implemented by a person of ordinary skill in the art in view of the present disclosure, which modifications would be within the scope of the present technology.