Abstract:
A bearing assembly for a hinge mechanism is described. The hinge couples a first component and a second component. The bearing assembly includes a ball, an outer ring, a pin and a fastener. The ball includes a bore at a center axis and a convex outer surface. The outer ring includes an outer surface affixed within the second component and a concave surface in rolling contact with the ball to define a primary slip path. The pin is located within the center bore. The pin is affixed to first and second outside surfaces of the fork. The fastener secures the pin such that the bearing assembly permits rotation of the outer ring and the second component along the primary slip path. A secondary slip path is defined by the ball rotating about the pin. The secondary slip path is engaged when rotation about the primary slip path fails.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This patent application claims benefit under 35 U.S.C. §119(e) of copending, U.S. Provisional Patent Applications, Ser. No. 60/763,186, entitled “High Lift System,” filed Jan. 26, 2006, the disclosure of which is incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates to spherical bearing assemblies and, more particularly, to a concentric spherical bearing assembly for movably coupling a first member to a second member. In one embodiment, the concentric spherical bearing assembly is included in a hinge assembly such as, for example, a lift-assisting hinge assembly of an aircraft.  
         [0004]     2. Description of the Related Art  
         [0005]     It is well known to use bearings to reduce friction between two moving parts of a mechanical assembly. Similarly, it is well known to use bearings in a hinge assembly movably coupling a first component to a second component. One implementation of such a hinge is within pivotable portions of a wing of an aircraft.  
         [0006]     An aircraft is kept airborne by the aerodynamic lift of its wings. Generally speaking, an aircraft wing comprises a main wing and lift-assisting devices (e.g., slats, flaps, spoilers, and the like) fixed to the wing for changing a lift coefficient during take-off and landing of the aircraft. Lift-assisting devices are typically affixed to a leading edge or a trailing edge of the aircraft wing. For example, one such lift-assisting device is a Fowler flap. The Fowler flap is affixed to the trailing edge of the wing to provide a control surface that is moved to the rear and below the trailing edge of the main wing and set at a predetermined angle. In this way the Fowler flap forms an air gap between a top and a bottom surface of the wing to increase an airfoil curvature of the wing while also increasing the surface area of the wing.  
         [0007]      FIG. 1  illustrates a conventional aircraft wing arrangement in a retracted state, shown generally at  100 , and an extended state, shown generally at  110 . The wing arrangement includes a main wing  101  and a Fowler flap  102  affixed to a trailing edge  103  of the main wing  101 . In the retracted state  100 , the Fowler flap  102  abuts the main wing  101 . In order to move the Fowler flap  102  from the retracted state  100  to the extended state  110 , a track mechanism  112  moves the Fowler flap  102  first to the rear of the main wing  101  and then folds the flap  102  downward to a position below the main wing  101 . In this way an air gap  111  is created between the main wing  101  and the extended Fowler flap  102 . As shown in  FIG. 1 , the Fowler flap  102  is attached to the trailing edge  103  of the main wing  101 .  
         [0008]     There has been a need to improve the lift performance of an aircraft wing with safer, more reliable components and particularly components of reduced weight and higher maintainability and quality. There has also been a need to improve hinges and bearings used in critical system such as, for example, aircraft control systems.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention is directed to a spherical bearing assembly for a hinge mechanism. The hinge mechanism couples a first component and a second component. The first component has a fork section forming a channel between portions of the fork section. The second component has a finger section. The spherical bearing assembly includes a bearing ball, an outer ring, a main pin and a fastener. The bearing ball includes a bore at a center axis and a spherically convex outer surface. The outer ring member includes an outer surface affixed within the finger section of second component and a spherically concave inner surface in rolling contact with the outer surface of the bearing ball. The rolling contact defines a primary slip path. The main pin is located within the center bore of the bearing ball.  
         [0010]     In one embodiment, a first end of the main pin is located at an first outside surface of the fork section and a second end of the main pin is disposed at a second outside surface of the fork section at an opposing side of the channel. The fastener secures the second end of main pin such that the spherical bearing assembly is located within the channel and permits rotation of the outer ring member and the second component along the primary slip path and about the center axis.  
         [0011]     In one embodiment, the outer ring member includes a flange abutting an inner surface of the fork section. The spherical bearing assembly further includes a fuse pin securing the flange to the inner surface of the fork section and inhibiting rotation of the bearing ball about the main pin.  
         [0012]     In one aspect of the invention, a secondary slip path is defined by the bearing ball rotating about main pin. The secondary slip path is engaged when rotation about the primary slip path fails and the fuse pin is sheared. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The features and advantages of the present invention will be better understood when the Detailed Description of the Preferred Embodiments given below is considered in conjunction with the figures provided.  
         [0014]      FIG. 1  illustrates a wing arrangement of an aircraft as is known in the art.  
         [0015]      FIG. 2  illustrates a dropped hinge mechanism for a main wing employing a bearing assembly configured and operating in accordance with one embodiment of the present invention.  
         [0016]      FIG. 3  is an isometric view of the hinge mechanism of  FIG. 2 .  
         [0017]      FIG. 4  is an enlarged, partially cross-sectional view of an Area  4  of  FIG. 3  taken along a hinge axis.  
         [0018]      FIG. 5  is a partial isometric view of the spherical bearing assembly and dropped hinge mechanism of  FIG. 2 .  
         [0019]      FIG. 6  is a cross-sectional view illustrating a bearing ball and race of the spherical bearing assembly of  FIG. 5 .  
         [0020]      FIG. 7  is an isometric view of the spherical bearing assembly configured and operating in accordance with one embodiment of the present invention.  
         [0021]      FIG. 8  is a plan view of the spherical bearing assembly of  FIG. 7 . 
     
    
       [0022]     In these figures like structures are assigned like reference numerals, but may not be referenced in the description of all figures.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     The following detailed description of the invention refers to the accompanying drawings. While the detailed description may refer to the invention used to improve a particular aspect of aircraft design, assembly and maintenance, the detailed description is not intended to limit the scope of the present invention. Rather, the scope of the invention is defined by the appended claims and equivalents.  
         [0024]     As noted above, various improvements to the Fowler flap, air gap manipulation and kinematic solutions for the same, are well known. For example, U.S. Patent Application Publication No. 2006/0202089, published Sep. 14, 2006, entitled “Aircraft wing, method for operating an aircraft wing, and use of a pivotable trailing edge on a main wing of an aircraft, for adjusting the shape and width of an air gap,” by Daniel Reckzeh et al. (Reckzeh et al.) discloses such improvements. In particular, Reckzeh et al. are seen to disclose a dropped hinge mechanism for supporting a Fowler flap and improvements in performance and aerodynamic characteristics thereof. The disclosure of the Reckzeh et al. patent publication is incorporated by reference herein in its entirety.  FIG. 2  illustrates, in a simplified form, a dropped hinge mechanism  200  of Reckzeh.  
         [0025]     As shown in  FIG. 2 , the dropped hinge mechanism  200  is affixed to a trailing edge  103 ′ of a main wing  101 ′ of an aircraft (not shown) for controlling a lift-assisting device such as, for example, a flap  102 ′. In one embodiment, the dropped hinge mechanism  200  includes a support beam  210  coupled to the main wing  101 ′, a support lever  240  coupled to the flap  102 ′ and a concentric spherical plain self-lubricated bearing assembly  300  disposed between and moveably coupling the support lever  240  to the support beam  210 . In accordance with the present invention, the spherical bearing assembly  300  allows the support lever  240  and flap  102 ′ to rotate about a hinge axis H between a retracted and an extended state (shown in dashed lines), as are generally known.  FIG. 3  is an isometric view of the dropped hinge mechanism  200  of  FIG. 2 .  
         [0026]      FIG. 4  is an enlarged, partially cross-sectional view of Area  4  of  FIG. 3  taken along the hinge axis H. In accordance with the present invention,  FIG. 4  details the coupling by the concentric spherical bearing assembly  300  of the support beam  210  and support lever  240  about the hinge axis H. As shown in  FIGS. 3-5 , the support beam  210  includes a fork section  212  having an outer surface  214  and an inner surface  216 . The inner surface  216  of the fork section  212  defines a channel  218  of a width sufficient to receive the spherical bearing assembly  300  ( FIG. 5 ). The support lever  240  includes a finger section  242  extending within the channel  218  of the fork section  212 . The finger section  242  includes a bore  244  dimensioned to receive an outer surface of the spherical bearing assembly  300 , as described below.  
         [0027]      FIGS. 6-8  illustrates the spherical bearing assembly  300  in accordance with one embodiment of the present invention. The spherical bearing assembly  300  includes a bearing ball  310  in slipping or rolling contact with an outer ring or race  314  along a spherically convex outer surface  312  of the bearing ball  310  and a complimentary spherically concave inner surface  316  of the race  314 .  FIG. 6  is a cross-sectional view illustrating the bearing ball  310  and race  314  of the spherical bearing assembly. In one embodiment, the spherical bearing assembly  300  includes a flange  320  facilitating coupling of the spherical bearing assembly  300  to the inner surface  216  of the fork section  212  by a pin such as, for example, a fuse pin  322 . The race  314  includes an outer surface  318  adapted for engagement (e.g., press fit) within the bore  244  of the finger section  242  of the support lever  240 . The bearing ball  310  includes a center bore  322 .  
         [0028]     A liner  330  is disposed in the center bore  322  ( FIG. 4 ). In one embodiment the liner  330  is comprised of a woven fluorocarbon-based polymer fabric material such as, for example, a PolyTetraFluoroEthylene (PTFE) fabric material. In one embodiment, the woven PTFE fabric material is commercially available under the designation FIBRILOID® (FIBRILOID is a registered trademark of Roller Bearing Company of America, Oxford, Conn.). In one embodiment, a liner  340  such as, for example, a FIBRILOID® liner, is disposed between the spherically convex outer surface  312  of the bearing ball  310  and the complimentary spherically concave inner surface  316  of the race  314 . It should be appreciated that the liners  330  and  340  provide the spherical bearing assembly  300  its self-lubricating characteristic. In one embodiment, with the liner  340  disposed between the bearing ball  310  and the race  314 , there is no clearance.  
         [0029]     A main pin  350  (e.g., a bolt) is disposed within the liner  330  and passes from one outer surface  214  of the fork section  212  to the opposing outer surface  214  of the fork section  212 . A fastener  352  (e.g., a nut) secures the main pin  350  within the fork section  212 , thus securing the spherical bearing assembly  300  within the fork section  212  of the support beam  210 . In one embodiment, the spherical bearing assembly  300  includes a locknut  334  used in combination with a lock washer  336  to hold the bearing ball  310  and race  314  in place on the main pin  350 .  
         [0030]     In one aspect of the invention, a primary slip path, shown generally at  400 , is defined by the rotation of the outer ring or race  314  about the bearing ball  310 . The primary slip path  400  of the spherical bearing assembly  300  facilitates rotation of the support lever  240  and, thus the flap  102 ′, about the hinge axis H as the support lever  240  and the flap  102 ′ are moved between the retracted and extended states as described herein. It should be appreciated, however, that the inventors have discovered that under certain operational conditions, the primary slip path  400  may fail such that rotation of the support lever  240  and the flap  102 ′ may be inhibited. In accordance with the present invention, the spherical bearing assembly  300  provides a secondary slip path, shown generally at  420 , to permit rotation of the support lever  240  and flap  102 ′ about the main pin  350  in the event that the primary slip path  400  fails, e.g., the race  314  is not able to rotate around the bearing ball  310 .  
         [0031]     As noted above, the spherical bearing assembly  300  includes the flange  320  secured to the inner surface  216  of the fork section  212  by the fuse pin  322 . Under normal operating conditions, e.g., when rotation occurs by means of the primary slip path  400 , the fuse pin  322  locks or inhibits rotation of the bearing ball  310 . In the case that the primary slip path  400  fails, the locking fuse pin  322  is sheared off, and the bearing ball  310  is allowed to rotate about the main pin  350 , e.g., about the secondary slip path  420 . It should be appreciate that in accordance with the present invention the motion of the support lever  240  is sufficient to shear the locking fuse pin  322  when rotation about the primary slip path fails. In this regard, the sheared fuse pin  322  is an indicator to, for example, maintenance personnel that the primary slip path  400  has failed.  
         [0032]     Exemplary aspects of the performance of the spherical bearing assembly  300  include the following:  
                                                                     Performance Parameter   Nominal Capability                                        Static Axial Limit Load   369   kN           Static Axial Ultimate Load   494   kN           Static Radial Limit Load   1,718   kN           Static Radial Ultimate Load   2,320   kN                      
 
         [0033]     The spherical bearing assembly  300  meets the following exemplary temperature requirements:  
                                                       Operating temperature   −55° C. to +79° C.           Equipment not operating   −55° C. to +85° C.                      
 
         [0034]     As is known in the art, other environmental conditions may impact performance of equipment, for example, equipment used on aircraft. For example, low temperature increases the coefficient of friction of bearing products. Altitude (pressure) is of minimal, if any, effect on bearing performance, other than the associated low temperatures existing at high altitude. Fluid and dirt contamination items can affect the performance of bearing products. It should be appreciated that the aforementioned FIBRILOID® liners are, by nature, non-metallic and self-lubricating as well as chemically resistant to fluids typically used in and around aircraft (e.g., de-icing fluid, hydraulic fluid, and the like). Moreover, the spherical bearing assembly  300  will operate reliably in any geographical location and normal environments including marine atmospheres, moisture, tropical temperatures, and soil and dust conditions in the atmosphere. The FIBRILOID® liner material is qualified to the specification AS 81820, as is known in the art.  
         [0035]     In one embodiment, the spherical bearing assembly  300  has a weight of about 2.7 kg, and its components are comprised of the following exemplary materials.  
                                                   Material           Component   Material   Specification   Heat Treat                   Race 314   17-4 PH   AMS 5643   COND H1150                   Rc 28-38       Ball 310   440C   AMS 5630   Rc 38-51       Locknut 334   PH 13-8 Mo   AMS 5629   Rc 38-51       Lockwasher 336   304 or equiv.   AMS 5910   Rc 28-31                   ¼ Hard       Liners 330 and 340   FIBRILOID ®   MPS 7-3050                  
 
         [0036]     Of note, 17-4 PH is steel comprised of a precipitation-hardening martensitic stainless steel that may comprise about 0.07% carbon; 0.6% manganese; 0.7% silicon; 0.03% sulfur; 0.04% phosphorous; 16% chromium; 4% nickel; 2.8% copper, 0.1% molybdenum; and 0.3% niobium.  
         [0037]     In one embodiment, the no load rotational breakaway torque of the spherical bearing  300  when not installed is from about 0.1 Nm to 2.5 Nm.  
         [0038]     In one embodiment, the coefficient of friction between the FIBRILOID® liner  340  and the bearing ball  310  is equal to or less than about 0.2 for the entire operating range of conventional aircraft. It should be appreciated that, for the self-lubricated bearing as described herein, the coefficient of friction is a function of the applied load, temperature, and relative “newness” of the bearing. Self-lubricating liner material such as the aforementioned FIBRILOID® material, require a “break-in” to begin the self-lubrication process. The coefficient of friction of an “as new” bearing employing FIBRILOID® liners is approximately 0.15 at room temperature and 34.5 MPa (5,000 psi) stress level. As the bearing begins to operate and the self-lubrication begins, the coefficient of friction will reduce to about 0.06 at room temperature. For PTFE lubricated bearings, the coefficient of friction will reduce as the stress level is increased. The minimum coefficient of friction will be approximately 0.05 at a stress level greater than 69 MPa (10,000 psi) and an elevated temperature 121° C. (250° F.). Generally, sub-zero temperatures will increase the coefficient of friction of self-lubricated materials by a factor of two or more.  
         [0039]     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, many construction techniques and materials may be utilized. Accordingly, other embodiments are within the scope of the following claims.