Metal working – Method of mechanical manufacture – Impeller making
Reexamination Certificate
2000-08-08
2001-08-28
Cuda Rosenbaum, I (Department: 3726)
Metal working
Method of mechanical manufacture
Impeller making
C029S889700, C029S897200, C228S190000
Reexamination Certificate
active
06279228
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a leading edge structure for an airfoil such as a main wing, a horizontal stabilizer, a vertical fin, an elevator or a rudder of an aircraft, and a method of fabricating such a leading edge structure. More particularly, the present invention relates to a leading edge structure for an aircraft, integrally formed with a hot air passage of an anti-icing system, and a method of fabricating the leading edge structure.
2. Description of the Related Art
The leading edge structure of an airfoil such as a main wing, a horizontal stabilizer, a vertical fin, an elevator or a rudder of an aircraft must have an anti-icing system to prevent the ice formation on the leading edge structure. The anti-icing system supplies hot air extracted from an engine compressor into the interior space of the leading edge structure covered by an outer skin so as to flow along the inner surface of the outer skin to raise the surface temperature of the outer skin and to prevent the ice formation on the outer surface of the leading edge structure.
Such a leading edge structure is disclosed in JP-A-9-71298. Referring to
FIG. 7
showing the prior art leading edge structure
100
for an aircraft disclosed in JP-A-9-71298 in a partially cutaway perspective view, an inner skin
102
of a fiber-reinforced plastic and a front wall
103
are disposed on the inner side of an outer skin
101
of a fiber-reinforced plastic. The outer skin
101
, the inner skin
102
and the front wall
103
are united by bonding to define a heating chamber
104
in the leading edge structure
100
. A rear wall
105
is disposed behind the front wall
103
to define a hot air discharge chamber
106
between the front wall
103
and the rear wall
105
. The heating chamber
104
is partitioned by the front wall
103
into a hot air jetting section
104
a
on the front side and a hot air passage section
104
b
on the rear side. An anti-icing duct
108
provided with a plurality of air jetting holes
108
a
is extended in the hot air jetting section
104
a
. Hot air flows through the anti-icing duct
108
. Hot air ejected through the hot air jetting holes
108
a
of the anti-icing duct
108
flows from the hot air jetting section
104
a
into the hot air passage section
104
b
, flows along hot air passages
104
c
formed in the hot air passage section
140
b
into the hot air discharge chamber
106
, and is discharged through a discharge hole formed in the tip of the wing into the atmosphere. The formation of ice on the leading edge structure
100
is prevented by thus making the hot air flow along the inner surface of the outer skin
101
of the leading edge structure
100
.
A method of fabricating this prior art leading edge structure
100
will be described hereafter. As shown in
FIG. 8A
, an outer skin prepreg sheet
112
for forming the outer skin
101
is placed on a shaping surface of a leading edge skin mold
111
having a shape corresponding to the external shape of the outer skin
101
. A comb-shaped silicone block
113
is placed as shown in
FIG. 8B
on the inner surface of the outer skin prepreg sheet
112
before hardening. An inner skin prepreg sheet
114
for forming the inner skin
102
is placed on the silicone block
113
so that parts thereof are forced into spaces between adjacent teeth to form straightening fins defining the hot air passages
104
c
. The leading edge skin mold
111
holding the outer skin prepreg sheet
112
, the silicone block
113
and the inner skin prepreg sheet
114
is placed in a vacuum bag, and the vacuum bag is evacuated, the outer skin prepreg sheet
112
and the inner skin prepreg sheet
114
are heated and compressed to unite the outer skin prepreg sheet
112
and the inner skin prepreg sheet
114
by bonding the straightening fins of the inner skin prepreg sheet
114
to the outer skin prepreg sheet
112
. Subsequently, the silicone block
113
is removed, the front wall
103
formed by a separate process is joined to the assembly of the outer skin prepreg sheet
112
and the inner skin prepreg sheet
114
(FIG.
8
C), and the anti-icing duct
108
is attached to the front wall
103
to complete the leading edge structure
100
.
Aluminum alloys have been used as materials for forming the leading edge structures of aircrafts because each of aluminum alloys has a small specific gravity and a high strength.
FIGS. 9
is a perspective view of an aluminum alloy leading edge structure
120
,
FIG. 10
is a sectional view taken on line X—X in
FIG. 9
, and
FIG. 11
is a sectional view taken on line X
1
—X
1
in FIG.
9
. The aluminum alloy leading edge structure
120
will be described with reference to
FIGS. 9
,
10
and
11
. An inner skin
122
formed by bending a corrugated sheet is extended along the inner surface of an outer skin
121
to form a hot air passage
123
extending along the inner surface of the outer skin
121
structure. A hot air outlet opening
122
a
is formed in a part of the inner skin
122
corresponding to the front edge of the leading edge structure
120
. A plurality of ribs
124
are attached to the inner skin
124
to divide a space defined by the inner skin
122
into a plurality of sections. A front wall
125
are attached to the rear edges of the inner skin
124
. Each rib
124
is provided with an opening
124
a
. An anti-icing duct
127
is extended through the openings
124
a
of the ribs
124
, and the anti-icing duct
127
is fastened to the ribs
124
by clips
128
formed by bending a sheet. As shown in
FIG. 12
in a perspective view, the anti-icing duct
127
is provided with a plurality of air outlet openings
127
a.
Hot air of a high temperature supplied into the anti-icing duct
127
is jetted through the air outlet openings
127
a
into the space defined by the inner skin
122
and the front wall
125
. Then, the hot bleed air flows through the hot air outlet opening
122
a
formed in the inner skin
122
into the space between the outer skin
121
and the inner skin
122
, flows through the same space along the inner surface of the outer skin
121
and is discharged through a discharge hole formed in the tip of the wing into the atmosphere. The hot air that flows along the inner surface of the outer skin structure
121
raises the surface temperature of the outer skin
121
to prevent the formation of ice on the surface of the leading edge structure
120
.
The outer skin
121
, the inner skin
122
and the rib
124
of the leading edge structure
120
are built by forming aluminum alloy sheets by press forming or roll forming, and finished by shaping the external shape by trimming. The clips
128
for fastening the anti-icing duct
127
to the ribs
124
are formed by bending an aluminum alloy sheet. The anti-icing duct
127
is formed by bending a tube of a titanium alloy or a stainless steel, and forming the plurality of air outlet openings
127
a
in the tube. The leading edge structure
120
is constructed by positioning these components of the leading edge structure
120
relative to each other by using jigs and adjusting shims, forming holes for receiving fasteners in the components, and fastening together the components with fastening means, such as rivets and clips.
When fabricating the former prior art leading edge structure
100
, the leading edge structure is formed by bonding together and hardening the outer skin
101
of a fiber-reinforced plastic, the inner skin
102
of a fiber-reinforced plastic, and the front wall
103
. Therefore, firm joints are formed between the outer skin
101
and the inner skin
102
by its own adhesive strength of the outer skin
101
and the inner skin
102
. However, since only the front wall
103
and the rear wall
105
spaced from the front wall
103
are extended between the upper and the lower section of the outer skin of the leading edge structure, there is the possibility that the leading edge structure
100
cannot be formed in a required strength. Furthermore, fabrication of the leading edge structure
10
Amaoka Kazuaki
Banno Michihiko
Kobayashi Takashi
Cuda Rosenbaum I
Fuji Jukogyo Kabushiki Kaisha
Smith , Gambrell & Russell, LLP
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