Patent Application
20070292062
1. Field of the Invention
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.
2. Description of the Related Art
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.
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.
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.
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.
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.
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.
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.
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.
In these figures like structures are assigned like reference numerals, but may not be referenced in the description of all figures.
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.
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.
As shown in
A liner 330 is disposed in the center bore 322 (
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.
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.
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.
Exemplary aspects of the performance of the spherical bearing assembly 300 include the following:
The spherical bearing assembly 300 meets the following exemplary temperature requirements:
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.
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.
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.
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.
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.
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.
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.
| Number | Date | Country | |
|---|---|---|---|
| 60763186 | Jan 2006 | US |
