Patent Application
20200040934
The present invention relates to systems and methods for assembling a strut at a threaded joint, and more particularly, for locking the threaded joint to prevent rotation and disassembly of the strut.
Large manufactured structures often use struts, or a large rod, bar or member to support large loads, typically to resist compression, tension, or torsion. One example of such a strut is used in the mounting apparatus of an engine on an aircraft. Aircraft are typically powered by gas turbine engines mounted to either the aircraft's fuselage, the tail, or the wings. The engine may be mounted using a variety of structures. Typically, particularly where the engine is mounted on a wing, the engine is mounted to a pylon attached to the wing via a thrust strut between the pylon and the engine.
The total weight of an aircraft is an important consideration in the design of an aircraft due to the role weight plays in fuel efficiency as well as other factors. Engineers typically consider the weight of each component added to the aircraft structure in designing the aircraft. The components used in mounting the engines are designed to be capable of withstanding the force of the thrust generated by the gas turbine engines and to remain firmly attached to the aircraft structure. The materials typically deemed best to provide the strength to reliably maintain the engines attached to the aircraft structure include metals, such as steel, aluminum, and other metals. The use of such materials results in a design tradeoff between the strength provided by metals and the increase in weight associated with these materials.
With respect to the thrust struts, the amount of metal used to sufficiently strengthen the thrust strut can be significant. One way to reduce the weight without unduly compromising the strength of the thrust strut is to manufacture the thrust struts as hollow members. Hollow thrust struts are typically manufactured as separate members that are hollowed out and then attached. The hollow members may be molded or bored and assembled using an attachment mechanism. One such attachment mechanism is a threaded joint having a threaded end on one member that screws into a corresponding threading in the cavity of the other member.
One problem with using threading is that it may loosen or unscrew during operation of the aircraft due to the forces exerted on the hollow thrust strut. The attached thrust strut members may be locked by inserting a pin into a hole located at the seam formed where the members attach. Typically, the pin is dimensioned so that when inserted, a pin surface sits below the surface of the members at the seam. The edges of the hole surrounding the pin are then knocked into the hole over the pin using a punch to lock the pin in place.
The pin prevents the strut members from rotating and possibly becoming unattached. The pin is locked in by the punched edges over the pin. However, the process of knocking the edges of the hole over the pin is dependent on the human use of the punch. The results are typically variable and may include instances when the pin slips out of the hole during the flight of the aircraft.
The thrust strut on an aircraft is only one example of a threaded strut that bears a substantial load and may be subject to forces that may act to unlock a threaded joint. Other struts having either a threaded attachment mechanism or another type of attachment mechanism may also require a locking pin to prevent rotational forces from causing an unintentional disassembly of the strut.
In view of the above, a strut is configured to support a load. The strut comprises a first strut member having a first attachment mechanism at a first abutment face. A second strut member having a second abutment face and a second attachment mechanism configured to receive the first attachment mechanism of the first strut member until the second abutment face is substantially in contact with the first abutment face. A pin is provided with an angled chamfer around at least one surface. A pin hole is formed in the strut to receive the pin. The pin hole is formed at a seam where the first abutment face and the second abutment face are substantially in contact. A locking ring surrounds the pin hole and formed as a channel in a surface of the strut. The channel may be formed with an angular lip extending from the surface. The angular lip is machined to lock the pin into the pin hole by a machining process.
In another aspect, a method is provided for assembling a strut. The method comprises inserting a threaded portion extending from a first abutment face of a first strut member into a thread formed inward from a second abutment face on a second strut member until the first abutment face is in substantial contact with the second abutment face. A pin hole is formed in a seam faulted where the first abutment face contacts the second abutment face. A locking ring is formed around the pin hole as a channel in a surface of the strut and an angular lip extending from the surface of the strut. A pin having a chamfered edge is inserted into the pin hole. The angular lip is machined to extend into the pin hole until the angular lip locks the pin in the pin hole.
Some examples of devices, systems, and methods for preventing rotation of a strut member at a threaded joint are outlined above rather broadly in order that the detailed description thereof may be better understood, and in order that the present contribution to the art may be better appreciated. Additional example implementations of the devices, systems, and methods are described below and will form the subject matter of the claims appended hereto. In this respect, before explaining at least one example of the devices, systems, and methods in detail, it is to be understood that the devices, systems, and methods are not limited in their application to the details of construction or to the arrangements of the components set forth in the following description or illustrated in the drawings. Other example implementations of the devices, systems, and methods may be developed, practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of the description and should not be regarded as limiting.
As used herein, the term “strut” shall mean any rod, bar or other member used to support a load by resisting compression, tension, and/or torsion. It is noted that example implementations of anti-rotations pins and locking rings for locking threaded joints are described below in the context of a strut for attaching an engine to an aircraft. Those of ordinary skill in the art will understand that example implementations of anti-rotations pins and locking rings described herein may also be used in other applications or structures without limitation.
With reference to
The gas turbine engine 100 works in a conventional manner so that air entering the air intake 111 is accelerated by the fan 112 to produce two air flows: a first air flow A into the intermediate pressure compressor 113 and a second air flow B which passes through the bypass duct 122 to provide propulsive thrust. The intermediate pressure compressor 113 compresses the air flow A directed into it before delivering that air to the high pressure compressor 114 where further compression takes place.
The compressed air exhausted from the high-pressure compressor 114 is directed into the combustion equipment 115 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines 116, 117, 118 before being exhausted through the nozzle 119 to provide additional propulsive thrust. The high, intermediate and low-pressure turbines 116, 117, 118 respectively drive the high and intermediate pressure compressors 114, 113 and the fan 112 by suitable interconnecting shafts extending through a rotational axis X-X.
Each of the high, intermediate and low-pressure turbines 116, 117, 118 and the intermediate and high-pressure compressors 113, 114 comprises at least one stage comprising a set of rotor blades and a set of stator vanes. In use, the rotor blades rotate around the engine axis X-X, while the stator vanes are stationary within the engine.
It will be appreciated that the gas turbine engine 100 if
Referring to
The first strut member 306 and the second strut member 308 are hollow. As shown in
The pin hole 520 may be sized to receive the pin 320. A locking ring 600 may be formed around the pin hole 520 as shown in
The use of the terms “a” and “an” and “the” and similar references in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the disclosure and does not pose a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure. Numerous modifications to the present disclosure will be apparent to those skilled in the art in view of the foregoing description. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the disclosure.
