Abstract:
A gas turbine engine air valve assembly has first and second valving elements. The second element is rotatable about a first axis relative to the first element. The rotation controls a flow of air through the first and second elements. An actuator is coupled by a linkage to the second element. The linkage includes a spindle having a first portion coupled to the actuator to rotate the spindle about a second axis. A guided spherical bearing couples a second portion of the spindle to the second element.

Description:
U.S. GOVERNMENT RIGHTS 
       [0001]    The invention was made with U.S. Government support under contract N00019-02-C-3003 awarded by The U.S. Navy. The U.S. Government has certain rights in the invention. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to a valve assembly for a gas turbine engine. Specifically, this invention relates to a valve assembly that controls the amount of cooling air supplied to a nozzle of a gas turbine engine. 
         [0003]    The major components of a typical gas turbine engine may include (beginning at the upstream end, or inlet) a compressor section, a burner (combustor) section, a turbine section, and a nozzle section. The engine may have an afterburner section between the turbine section and the nozzle section. 
         [0004]    If the engine is a turbofan, then the compressor section includes a fan section, typically at the upstream end. After passing the fan section, the turbofan engine separates the air into two flow paths. A primary flow (also referred to as core engine flow) enters the remainder of the compressor section, mixes with fuel, and combusts in the burner section. The gases exit the burner section to power the turbine section. 
         [0005]    A secondary flow (also referred to as bypass flow) avoids the remainder of the compressor section, the burner section and the turbine section. Instead, the secondary flow travels through a duct to a location downstream of the turbine section. The secondary flow mixes with the primary flow downstream of the turbine section. 
         [0006]    The afterburner section may augment the thrust of the engine by igniting additional fuel downstream of the turbine section. The flow then exits the engine through the nozzle. 
         [0007]    The engine may supply cooling air to the nozzle in order to protect the nozzle components from the high temperature exhaust. Typically, the engine diverts secondary flow from the fan section to cool the nozzle section. 
         [0008]    The greatest demand for cooling air to the nozzle occurs when the afterburner operates. As an example, the pilot operates the engine at maximum thrust (with the afterburner operating) in a conventional take-off and landing (CTOL) operation. CTOL operation typically requires a large amount of cooling air for the nozzle. 
         [0009]    Certain non-augmented operations of the engine (i.e., without the afterburner operating) also require cooling air. However, the amount of cooling air need is typically a reduced amount from augmented operations. As an example, a short take-off vertical landing (STOVL) operation typically requires maximum non-augmented thrust from the engine. The non-augmented exhaust, while still at an elevated temperature, typically exhibits a lower temperature than during augmented operations. Accordingly, the engine can accept a reduced supply of cooling air for the nozzle in STOVL operation. 
         [0010]    Flow of the cooling air may be controlled by one or more valves. Exemplary valve structures are shown in U.S. Pat. No. 6,694,723, the disclosure of which is incorporated by reference herein as if set forth at length. 
       SUMMARY OF THE INVENTION 
       [0011]    One aspect of the invention involves a gas turbine engine air valve assembly having first and second valving elements. The second element is rotatable about a first axis relative to the first element. The rotation controls a flow of air through the first and second elements. An actuator is coupled by a linkage to the second element. The linkage includes a spindle having a first portion coupled to the actuator to rotate the spindle about a second axis. A guided bearing couples a second portion of the spindle to the second element. The bearing may be a spherical bearing. The rotation may be in the absence of translation. The assembly may be provided in a reengineering or remanufacturing situation. 
         [0012]    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a partially schematic cut-away view of an exemplary gas turbine engine in a first condition/configuration. 
           [0014]      FIG. 2  is a view of the engine of  FIG. 1  in a second condition/configuration. 
           [0015]      FIG. 3  is a partial longitudinal view of a nozzle cooling valve of the engine of  FIG. 1  in a first orientation. 
           [0016]      FIG. 4  is a partial longitudinal view of the nozzle cooling valve of the engine of  FIG. 1  in a second orientation. 
           [0017]      FIG. 5  is a view of a linkage of the valve of  FIG. 3 . 
           [0018]      FIG. 6  is an exploded view of the linkage of  FIG. 5 . 
       
    
    
       [0019]    Like reference numbers and designations in the various drawings indicate like elements. 
       DETAILED DESCRIPTION 
       [0020]      FIGS. 1 and 2  show an exemplary engine  100  in two different configurations.  FIG. 1  shows the engine  100  in a first configuration, such as a conventional take-off and landing (CTOL) configuration.  FIG. 2  shows the engine  100  in a second configuration, such as a short take-off vertical landing (STOVL) configuration.  FIG. 2  also shows, in phantom line, the engine  100  in transition between the CTOL and STOVL configurations. 
         [0021]    The engine  100  has an inlet  101 , a compressor section  103 , a burner section  107 , a turbine section  109 , an afterburner section  111 , and a nozzle section  113 . The compressor section  103  includes a fan section  105  at the upstream end. The engine  100  also includes a bypass duct  115  for the secondary flow of air. The air flows through the engine  100  in the direction indicated by arrow F. The engine spools or rotors rotate about an axis  500  which may be at least partially coincident with an engine centerline  502 . In the STOVL configuration, the centerline  502  departs from the axis  500  downstream of the rotors. 
         [0022]    The nozzle section  113  includes a three bearing swivel duct  116  secured to the afterburner section  111  and a nozzle downstream of the duct. The three bearing swivel duct has three sections  117 ,  119 ,  121 . The first section  117  rotatably mounts to the afterburner section  111 . The second section  119  rotatably mounts to the first section  117 . Finally, the third section  121  rotatably mounts to the second section  119 . Conventional motors (not shown) can rotate the sections  117 ,  119 ,  121  to any desired exhaust path between the first configuration shown in  FIG. 1  and the second configuration shown in  FIG. 2 . 
         [0023]    The nozzle can be a conventional flap-type convergent-divergent nozzle  123  or any other suitable nozzle. The nozzle  123  is secured to the third section  121  of the swivel duct. 
         [0024]    The nozzle section  113  includes a liner (not shown). The liner separates the outer structure of the nozzle section  113  from the hot exhaust gases traveling through the nozzle section. The liner and the outer structure  126  of the nozzle section  113  form an annular chamber  127  ( FIG. 3 ). The engine  100  distributes cooling air through the annular chamber to cool the liner. After cooling the liner, the cooling air continues downstream to cool the nozzle flaps. A bleed (not shown) from the bypass duct  115  supplies the cooling air to the nozzle section  113  using conventional techniques. 
         [0025]    A valve assembly  200  ( FIG. 3 ) controls the amount of cooling air supplied to the nozzle flaps. The exemplary valve assembly includes an annular rotary gate  202  which may be rotated about the local engine centerline  502  ( FIG. 2 ). The gate  202  has a circumferential array of apertures  204 . The apertures  204  may have a degree of overlap with apertures  206  in a static element  208  abutting the gate  202 . The rotation of the gate  202  between first and second orientations determines the degree of aperture overlap (and thus of non-occlusion) and thus the effective flow area through the valve between minimum and maximum values. The minimum value may be zero (e.g., fully closed) or some greater amount. For example, the  FIG. 3  condition is approximately half occluded and may represent a minimum flow area condition.  FIG. 4  shows essentially no occlusion and thus a maximum flow area condition. 
         [0026]    Rotation of the gate between the first and second orientations may be achieved by means of an actuator  220  acting via a linkage  222 . The exemplary linkage  222  includes a spindle  224  held for rotation about an axis  520  (e.g., a radial axis orthogonal to and intersecting the engine centerline). The actuator  220  may rotate the spindle  224  between first and second orientations associated with the first and second gate orientations/conditions. The actuator  220  may be pneumatic, hydraulic, electrical, electro-mechanical, or any other appropriate type. For example, the actuator  220  may be constructed as in U.S. Pat. No. 6,694,723 (the &#39;723 patent). 
         [0027]      FIGS. 3 and 4  show further details of the valve assembly  200 . The static element  208  is shown unitarily-formed with and extending radially inboard from a proximal/upstream portion of the outer structure  126  of the nozzle  123 . The exemplary gate  202  is immediately forward/upstream of the element  208  with the downstream face of the gate  202  facing the upstream face of the element  208 . The gate  202  is held for its rotation by support means (not shown). Exemplary support means could comprise a rotary bearing structure permitting rotation of the gate  202  but preventing longitudinal translation and radial shifts. Alternative means could include fasteners secured to one of the gate  202  and element  208  and having a limited range of motion (e.g., along a circumferential slot) in the other. In such a system, the slot ends could act as stops. Yet further alternative means could include an idler crank array as in the &#39;723 patent providing a path combining rotation with longitudinal translation. 
         [0028]      FIGS. 5 and 6  show further details of the linkage  222 . A spindle  224  includes a spindle shaft  240 . An intermediate portion of the shaft  240  is received within a bushing  242  (e.g., a two-piece bushing). The bushing  242  may be secured within an aperture in the engine static structure (e.g., the exemplary third duct section  121  of  FIG. 4 ). The shaft  240  is thus held by the bushing  242  for rotation about the axis  520 . An outboard portion of the spindle shaft  240  includes an input/driving clevis  244 . The exemplary clevis  244  is formed by arms  246  and  248  secured (e.g., by welding) to the shaft outboard portion. An input/driving pin  250  spans the arms  246  and  248  and has an axis  522  parallel to and spaced apart from the axis  520 . The pin  250  is engaged by the actuator to rotate the spindle  224  about the axis  520 . An inboard end of the spindle includes an output/driven clevis  260 . The exemplary clevis  260  includes a clevis body  262  separately formed from the spindle shaft and mounted thereon by means of complementary splines. Exemplary splines include external splines  264  ( FIG. 6 ) along the spindle shaft inboard portion and internal splines  266  within the body  262 . A bolt or other fastener  268  may extend through the body  262  spanning an expansion slot to secure the body  262  to the shaft  240  against translation. 
         [0029]    The body  262  includes arms  270  and  272 . A driven/output clevis pin  274  spans the arms and has an axis  524  parallel to and spaced apart from the axis  520 . Alternative implementations might include non-parallel axes  522  and/or  524  (e.g., axes intersecting the axis  520  or skew thereto). A spherical bearing  276  has an inner bore receiving the shaft of the pin  274  between the arms  270  and  272 . In the exemplary embodiment, the bearing  276  and shaft cooperate to permit the bearing to have non-zero ranges of movement along the axis  524  and rotation about the axis  524 . 
         [0030]    The bearing  276  is received within a slot  280  in a follower bracket  282 . The exemplary bracket  282  includes a base  284  for mounting to the gate  202 . A pair of arms  286  and  288  extend forward from the base  284  to define the slot  280  therebetween. Inboard surfaces  290  of the arms  286  and  288  have a concavity complementary to a convexity of the external surface of the bearing  276 . The exemplary surfaces  290  are singularly concave to allow the bearing  276  to translate along the slot from a proximal root of the slot to a distal end of the slot. In the exemplary embodiment, the base  284  is secured against a forward/upstream surface of a web  300  of the gate  202  between inboard and outboard flanges. The securing may be by means of fasteners  302  (e.g., rivets). The base may further include a registration protrusion (not shown) for interfitting with a complementary aperture or socket  304  in the web  300 . 
         [0031]    In operation, movement of the actuator produces a rotation of the spindle  224  about the axis  520 . This, in turn, tends to rotate the axis  524  about the axis  520 . Rotation of the axis  524  about the axis  520  causes the bearing  276  to transmit a tangential force and thus a torque (about the engine centerline) to the follower  282  and thus to the gate  202 . This torque causes rotation of the gate about the engine centerline so as to control the degree of aperture overlap and thus the flow through the valve. 
         [0032]    During rotation of the gate, the axis  524  will tend to shift longitudinally (e.g., toward or away from the gate). This shift is accommodated by the sliding interaction of the bearing  276  longitudinally within the slot  280  and radially along the pin  274 . This sliding interaction decouples the longitudinal motion of the axis  524  from any longitudinal motion of the gate  202 . For example, the gate  202  may exclusively rotate. Alternatively, the gate  202  may have a relatively small translation (e.g., if mounted by idler cranks in such a way that the permitted translation breaks a seal between the gate and the ring  208 ) so as to avoid sliding friction between the gate and ring. 
         [0033]    The exemplary valve assembly  200  may be provided in the remanufacturing of a baseline engine or the reengineering of a baseline engine configuration. The baseline could lack such a valve assembly. For example, the baseline could have a different valve assembly such as that of the &#39;723 patent. This might be particularly relevant if the reengineering included elimination of the idler crank mounting means of the &#39;723 patent in favor of a purely rotational gate movement. 
         [0034]    One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, when applied in a reengineering or remanufacturing of an existing engine or engine configuration, details of the existing engine or configuration may influence details of any particular implementation. Additionally, the valve could be otherwise located (e.g., relatively upstream at a bleed plenum). Accordingly, other embodiments are within the scope of the following claims.