Supports – Pipe or cable – Brackets
Reexamination Certificate
1999-09-30
2003-12-02
Johnson, Blair M. (Department: 3634)
Supports
Pipe or cable
Brackets
Reexamination Certificate
active
06655642
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to clamps and, more particularly, to strap clamps for securing tubing to an aircraft engine housing.
Aircraft engine assemblies require a vast number of pipes and tubes to be connected between components. The tubing and piping is often routed in a space located between an aircraft engine housing and an aircraft engine cowling. Although isolated, this area is still subjected to the high temperatures and high vibrations operated by the aircraft engine. As a result, any clamp assemblies securing tubing in these areas are also subjected to the high temperatures and high vibrations. Typically these clamp assemblies include a bracket assembly anchored to the aircraft engine housing, and a clamp positioned around the tubing to be anchored and attached to the bracket assembly. Because the bracket assembly is typically secured more rigidly to the aircraft engine housing than the clamp is capable of being secured to the bracket, the clamp is subjected to much more stress than the clamp bracket.
Clamping systems typically utilize a multi-piece clamp which consists of a flat base member and an upper member welded to the base member. Often the upper member is pre-formed to fit around a specific outer diameter of piping to be anchored. Additionally, often the lower member is also pre-formed to receive a specific outer diameter of piping. A problem with known clamps is that under the high vibrations encountered by the clamping assemblies, the clamps have a tendency to crack and fail due to vibrational fatigue. In particular, those clamps that are pre-formed have a tendency to fail at a location near the apex of the pre-formed bend or at any of the weld locations between the members. In some instances, these failures lead to failure of the base member and eventually to a failure of the particular tubing being secured to the housing.
BRIEF SUMMARY OF THE INVENTION
In an exemplary embodiment of the invention, a lower strap clamp installs easily, is reliable, and is resilient to vibrations induced by an aircraft engine.
The lower strap clamp includes an elongate body having a unitary first portion and a second portion. The first portion has a first thickness and the second portion has a second thickness which is thicker than the first thickness. The elongate body is rigid and remains flat when tubing is anchored to it. The second portion is generally rectangular shaped and extends from the first portion. Since the second portion is unitary with the first portion, no welds are utilized on the strap clamp. The lower strap clamp includes a plurality of apertures which receive threaded connectors used to anchor the strap clamp to a structure.
During assembly, a wear sleeve is attached and encircles the tubing being anchored. An upper strap includes a plurality of openings and is bent and formed around the tubing such that the openings on the upper strap clamp align with the apertures on the lower strap clamp. The fasteners pass through the upper strap clamp and extend through the lower clamp bracket to anchor the tubing to the structure. As a result, the risk of the lower clamp failing due to the high vibrations induced by the aircraft engine is minimized.
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Andes William Scott
Armstrong Teasdale LLP
General Electric Company
Johnson Blair M.
Novosad Jennifer E.
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