Clip attachment

The segmented wall of the float-wall combustor liner for a gas turbine engine is retained by a clip secured to a post extending radially from the outer wall through an opening in the segmented wall. The clip serves to load the walls radially and has fail-safe features preventing inadvertent dislodging.

DESCRIPTION 
1. Technical Field 
This invention relates to clip attachments and particularly to clip 
retention mechanism for securing the float-wall panels to the outer shell 
of the combustor liner for a gas turbine type power plant. 
2. Background Art 
This invention constitutes an improvement over U.S. Pat. No. 4,302,941 
granted to T. L. DuBell on Dec. 1, 1981 entitled "Combustion Liner 
Construction for Gas Turbine Engine" and assigned to United Technologies 
Corporation, the same assignee as this patent application. Suffice it to 
say that the floatwall combustor wall consists of an outer shell which may 
be formed in a complete hoop or segmented and has attached thereto a 
plurality of free floating segments that are adapted to be displaced 
axially and circumferentially in response to the thermals of the system. 
Such designs are capable of withstanding the hostile environment which 
they are subjected with an improved durability characteristic. 
The problem inherent in the float-wall Combustor design is the attachment 
of the floating wall segments to the outer shell. One such scheme used 
heretofore is forming a hook integral with the segmented float-wall panel 
that passes through an aperture in the outer shell to which is attached a 
strap and such a system is relatively complex and expensive. 
This invention comtemplates attaching the floatwall panels by a spring clip 
adapted to fit onto an integral post so as to preload the panel in a 
radial direction. Because this is virtually the only load on the spring 
clip notwithstanding the high temperature environment, such a retention 
system is highly durable, improving the maintainability of the combustor 
liner. Since the clips are removable without damage to the post. the 
removal of panels is facilitated which enhances the maintainability of the 
combustor. 
Another aspect of this invention is a novel clip design adapted to secure a 
removable assembly with the clip which is clipped onto a cooperating post. 
The clip is characterized by being self-retaining with protection against 
inadvertent dislodging and capable of imparting a radial load to the 
assembled parts. 
Disclosure of Invention 
An object of this invention is to provide for the combustor of a turbine 
type power plant and improved retention means for float-wall segmented 
panels. A feature of this invention is that a spring clip fits an integral 
post formed on the float-wall panel and spring loads the panel to the 
outer shell while allowing axial and circumferential movement relative to 
each other. Another feature of this invention is that the spring clip is 
designed to prevent itself from becoming dislodged as is the case of 
heretofore known spring clips. Another feature of this invention is the 
design of the slot in the post to prevent rotation of the clip and 
facilitate the insertion of the clip. 
Another feature is an improved spring clip retention which is characterized 
as being relatively inexpensive and retains the installed parts in a 
positive manner.

BEST MODE FOR CARRYING OUT THE INVENTION 
While this invention in its preferred embodiment constitutes an improvement 
on the float-wall segmented panels as described in U.S. Pat. No. 
4,302,941, supra, and utilized for aircraft engines manufactured by 
Government Products Division of United Technologies Corporation it is to 
be understood that this retention system may be employed in other types of 
combustor liner configurations or components of the engine. For example, 
such an improvement may be utilized in the transition duct leading the 
combustion products from the can burners to the turbine inlet. 
As noted from FIGS. 1-4 the combustor 10 (only partially shown) comprises 
outer shell generally indicated by reference numeral 12 and an inner liner 
generally indicated by reference numeral 16. The inner liner 16 defining 
the flow path of the engine's working medium consists of a plurality of 
segments 18 spaced around the circumference of the shell and extending 
axially along the flow path. Each segment 18 carries at least one integral 
post 20 that is adapted to extend radially through apertures 22 formed in 
shell 12. As noted, posts 20 are slotted at diametrically opposed sides 21 
and 23, in a direction specifically related to the cooling air holes 24. 
In this instance these slots are generally parallel to the row of cooling 
air holes 24. The important consideration is that the slots are designed 
so that when the clip is assembled it does not rotate and obstruct these 
cooling air holes 24. Each side of the lower shoulder 25 adjacent the 
slots 21 and 23 is beveled at 30 and 32 as shown in FIG. 2. This ramp 
serves to facilitate the assembly of the clip. 
The clip 36 is best shown in FIGS. 4 and 5 as comprising a relatively 
U-shaped unitary unit stamped out of a relatively thin flat stock of 
highly resilient and flexible material. Obviously, the metal selected must 
be capable of withstanding the hostile environment and must be 
sufficiently flexible and resilient to impart a spring load to the panels 
28 and shell 12 as will be described hereinbelow. 
Each leg 38 and 40 of the U-shaped clip extend from the radius 42 
relatively parallel but bent toward each other so as to meet at a point of 
contact. 
The inner leg 38 (the leg adjacent shell 23) is sinusoidally shaped so that 
the high points 46 and 48 contact the face of shell 12 at points 
straddling the aperture 22. 
The holes in each of the legs 38 and 40 are specifically designed to assure 
(1) proper orientation of the clip, (2) prevention of falling off the post 
once installed and (3) restrain to rotate. As noted from FIG. 4, the inner 
leg 38 is longer than the outer leg 40 and the hole 50 is axially spaced 
from hole 52. The diameter of each hole 50 and 52 is dimensioned slightly 
larger than the diameter of post 18. The inner leg 38 is further slotted 
from the edge of hole 50 to form opening 49 and extending to underlie the 
hole 52 and is dimensioned to fit the reduced size of post 20 between the 
diametric slots 21 and 23. This serves to orient the clip and prevents 
rotation thereof. Additionally the inner face of leg 38 bears against the 
shoulder 25 urging the panel 18 toward shell 12. This radially loads the 
shell and panel toward each other, while allowing circumferential and 
axial movement relatively to each other, so as to minimize chattering and 
hence preventing any acoustical problems that might otherwise occur and 
minimizing cycle fatigue problems. 
As is apparent from the foregoing and inasmuch as the clip completely 
encircles the post 20 the clip is unable to slip off and hence cannot 
become dislodged, which would otherwise be untolerated, to avoid the 
possibility of it being injested in the engine's turbine. The retaining 
force of the outer leg 40 of clip 36 can be adjusted simply by removing 
material in the radius portion 42 as for example locating a hole in the 
arc segment of radius 42. 
While in certain installations it may be possible to assemble the clip by 
hand, in others it may be necessary to use a mounting tool. Such a tool 
could be a suitable pliers modified to hold the clip where one member 
bears against the radius end of the clip and the other member bears 
against the post forcing the clip to ride up the ramp 32 fitting the 
slotted section 49 when the handle of the pliers are squeezed together.