Patent Application
20170191446
Technical Field
The present invention relates generally to aircraft gas turbine engine cowls and, more specifically, to a V-blade and V-groove used to help keep the cowls closed.
Background Information
Aircraft bypass gas turbine engines typically employ thrust reversers for ground deceleration. The thrust reversers may be located in the fan bypass duct radially between an outer nacelle and an engine core cowl and axially between a fan and a fan nozzle. One type of thrust reverser envelops the engine around its circumference for the length of the reverser. For maintenance, to access the portion of the engine that is enveloped by the thrust reverser, the thrust reverser may be located within an outer cowling constructed as two clamshell structures that are pivoted from the pylon and can be opened when the engine is not in service.
The clamshells hinge upon the aircraft pylon with the forward end of the clamshell having a tongue-in-groove fit to the main engine that serves two purposes when the engine is operating. The first purpose is to seal the flow that is directed from the fan bypass into either the thrust reverser or fan nozzle. The second purpose is to provide support of the thrust reverser at its forward end. Typically, only a latch opposite the clamshell hinge holds the two halves of the clamshell together. This latch provides hoop integrity of the two clamshells during engine operation, but otherwise, does not further constrain the thrust reverser tongue (often called the V-Blade) in the engine groove (often called the V-groove). The tongue is often called a V-blade and is usually on the cowl and fits into the engine groove often called V-groove on an engine fan casing. Clamping apparatus incorporating knife-edges and mating grooves (similar to V-blades and corresponding V-grooves) have been used to secure or clamp the cowls.
There is often a lot of relative motion at an interface between the V-blade and V-groove due to the inherent flexibility of the thrust reverser clamshell halves, the lack of rigidity due to there only being two circumferential points of constraint of the clamshell halves, and the high vibratory environment induced by buffeting aero loads, especially during thrust reverser deployment. High contact stress and relative motion between these V-blade and V-groove structures necessitates a wear coating at a contact surface between the two in order to keep the two parts from excessively fretting each other, which can either dimensionally compromise the load carrying capacity of the joint and/or expose it to further deterioration by corrosion.
Some wear coatings at this joint have included metalized coatings of some sort such as Cu—Ni—IN or hard anodize usually applied to both the V-groove and V-blade. A more robust wear protection is desired to provide a longer life and greater durability.
A clamping assembly (22) includes an annular molded composite wear sleeve (40) bonded with epoxy or other bonding agent in an annular V-groove (34) in a groove ring (64). The wear sleeve (40) may include forward and aft sleeve walls (46, 48) extending at forward and aft sleeve obtuse angles (50, 52) respectively away from a sleeve bottom (44) and annular forward and aft sleeve fillets (54, 56) may be between the sleeve bottom (44) and the forward and aft sleeve walls (46, 48). The aft sleeve wall (48) may include an aft flap (60) compliant with an annular aft taper (62) on the annular groove ring (64) containing the V-groove (34).
An aircraft gas turbine engine cowl clamping mechanism (22) for clamping a clamshell cowl (20) to a fan casing (26) includes the groove ring (64) on a fan casing (26) and the annular molded composite wear sleeve (40) bonded with epoxy or other bonding agent in the annular V-groove (34) in the groove ring (64). An annular V-blade (30) may be attached to the clamshell core engine cowl (20) which is rotatable to insert the annular V-blade (30) in the annular V-groove (34).
An aircraft turbofan gas turbine engine (10) includes a reverser (80) and a bypass duct extension (84) mounted to a clamshell core engine cowl (20) and radially spaced apart inner and outer cowl clamping mechanisms (90, 92) clamping radially spaced apart annular inner and outer duct walls (94, 96) of the bypass duct extension (84) to radially spaced apart annular inner and outer fan casings (100, 102) respectively of the engine (10). The inner and outer cowl clamping mechanisms (90, 92) include inner and outer V-blades (106, 108) on forward ends (110) of the inner and outer duct walls (94, 96) and inner and outer V-grooves (112, 114) in inner and outer groove rings (120, 122) on aft ends (116) of the inner and outer fan casings (100, 102) respectively. Annular inner and outer molded composite wear sleeves (40) are bonded with epoxy or other bonding agent in the inner and outer V-grooves (112, 114) respectively. The clamshell core engine cowl (20) may be rotatable for inserting the inner and outer V-blades (106, 108) in the inner and outer V-grooves (112, 114) respectively.
A method for preventing excessive fretting between annular V-blades (30) and mating annular V-grooves (34) in groove ring (64) includes bonding an annular molded composite wear sleeve (40) with epoxy or other bonding agent in the annular V-groove (34) in a groove ring (64) or on a matable V-blade (30). The method may include grit blasting or otherwise removing old and possibly corroded material from a V-groove surface (72) of the annular V-groove (34) before bonding the wear sleeve (40) in the V-groove (34). The method may include grit blasting down to bare metal of the V-groove surface (72) then coating the entire bare V-groove surface (72) with a structural bonding agent (74) that is resistant to corrosion.
The method may further include laying on the annular molded composite wear sleeve (40) and fitting the wear sleeve (40) to a three dimensional contour of the V-groove (34) such that essential points of contact for load transferal between the V-blade (30) and the V-groove (34) are formed after the coating of the entire bare V-groove surface (72) with the structural bonding agent (74). The method may be performed with the engine mounted on an aircraft.
The invention, in accordance with preferred and exemplary embodiments, is more particularly described in the following detailed description taken in conjunction with the accompanying drawings in which:
The V-blades 30 and the V-grooves 34 are annular and the V-blades 30 mate or fit into the V-grooves 34 when the clamshell core engine cowls 20 are rotated about hinges (not illustrated herein) and closed as is well known in the cowl field. When the clamshell cowls 20 are closed and the V-blades 30 are received in the V-grooves 34, there is often a lot of relative motion at this V-blade to V-groove interface 38 due to the inherent flexibility of the clamshell cowls 20 or other types of cowls used in aircraft engine nacelles. There is a lack of rigidity due to there only being two circumferential points of constraint of the clamshell cowl halves. This is also a highly vibratory environment induced by buffeting aero loads, especially during thrust reverser deployment.
The high contact stress and relative motion between the V-blades 30 in the V-grooves 34 has previously led to the adoption of metalized wear coatings, such as Cu—Ni—IN or hard anodize, on the contact surfaces of the V-blade to V-groove interface 38 in order to keep the two parts from excessively fretting each other. This fretting can dimensionally compromise the load carrying capacity of the clamping joint and/or expose it to further deterioration by corrosion. However, these metalized wear coatings still do not have adequate durability against this fretting and/or corrosion and must be refurbished many times within the normal life cycle of an engine.
Disclosed herein and illustrated in
The molded composite wear sleeve 40 illustrated in
The wear sleeve 40 may be a composite material including a Kevlar/Teflon weave, Fiberglass/Teflon weave, or other wear resistance weave coating. Examples of such materials are Dupont CP-0664, Kamatics Karon V, Kamatics P54, and Ultem 4001. The wear sleeve 40 may be made from a wear strips which are well known and are manufactured by companies such as Dupont and KAMATICS CORPORATION. DuPont's Vespel wear strips provide a suitable wear strip material for the wear sleeve 40. Vespel wear strips may be made from sheet-molded and fabric reinforced polyamide resin composite materials. The KAMATICS CORPORATION makes a wear strip material known as KAron wear strip material in the form of a fiberglass/epoxy backing of variable thickness with the KAron V liner system applied to one or both sides of the fiberglass. The KAron liner system is available in sheet or strip form and is well known for use in problem areas involving unintentional rubbing, scuffing or fretting.
The wear sleeve 40 may be bonded to the substrate 63 such as the groove ring 64 during new manufacture or as a repair or overhaul process. One exemplary method suitable for repair or refurbishment of the groove ring 64 includes grit blasting or otherwise removing old and possibly corroded material from a V-groove surface 72. The substrate 63 is grit blasted down to bare metal of the V-groove surface 72 then the entire bare V-groove surface 72 is coated with a structural bonding agent 74 that is resistant to corrosion. Then the molded wear sleeve 40 is laid on to the bonding agent 74 that fits a three dimensional (3D) contour of the V-groove 34 in such a way so that they form the essential points of contact for load transferal between the V-blade 30 and the V-groove 34. The bonding agent should be durable against the compressive and shear loads that the V-blade 30 transmits to the V-groove 34.
Suitable bonding agents include epoxy in liquid, paste, or film, or other adhesive types, that cures at room temperature or elevated temperatures and sufficiently bonds the wear sleeve in place so as to withstand the V-groove/blade loading and corrosive environment. Examples of such bonding agents include Hysol EA9394, Hysol EA9396, 3M AF3901 Film adhesive, 3M AF163 Film Adhesive, RTV/silicone rubber adhesives, Hyso19309, Hysol EA9460, 3M Scotchweld 460, and Araldite 2011. The repair or refurbishment method may be done with the engine still mounted on the aircraft such as on the wing or on an aircraft's fuselage.
Molded composite wear sleeves 40 illustrated in
While there have been described herein what are considered to be preferred and exemplary embodiments of the present invention, other modifications of the invention shall be apparent to those skilled in the art from the teachings herein, and it is, therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the invention.
Accordingly, what is desired to be secured by Letters Patent of the United States is the invention as defined and differentiated in the following claims:
| Number | Date | Country | Kind |
|---|---|---|---|
| P.415487 | Dec 2015 | PL | national |
