Note: Descriptions are shown in the official language in which they were submitted.
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PROPELLER BLADE ASSEMBLY
BACKGROUND OF THE INVENTION
[0001] Contemporary vehicles, such as hovercrafts, may include propeller
blades to
provide propulsive force. The propeller blades may be exposed to environments
that
erode portions of the propeller blades. Propeller failures may be caused by
sand and
stone nicks to the leading edge.
BRIEF DESCRIPTION OF THE INVENTION
[0002] In one aspect, an embodiment of the invention relates to a propeller
blade
assembly, having a propeller blade having a leading edge, a replaceable guard
selectively
mountable to the propeller blade to cover at least the leading edge, and
multiple fasteners
selectively coupling the replaceable guard to the propeller blade and wherein
at least one
of the multiple fasteners does not extend beyond an exterior of the
replaceable guard.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] In the drawings:
[0004] Figure 1 is a schematic embodiment of an environment in which a
propeller
blade assembly may be used.
[0005] Figure 2 is a top view of a propeller blade assembly according to an
embodiment of the invention.
[0006] Figure 3 is a cross-sectional view of a portion of a propeller blade
assembly
according to an embodiment of the invention.
[0007] Figure 4 is an alternative cross-sectional view of a portion of the
propeller
blade assembly of Figure 3.
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[0008] Figure 5 is a cross-sectional view of a portion of a propeller blade
assembly
according to another embodiment of the invention.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0009] Figure 1 schematically illustrates a vehicle, more specifically a
hovercraft 8,
in which a propeller blade assembly 10 may be used. It will be understood that
the
propeller blade assembly 10 may be used in any suitable vehicle and
hovercraft. Figure 2
illustrates a propeller blade assembly 10 having a propeller blade 12, a
replaceable guard
14, and multiple fasteners 16. The propeller blade 12 may have an airfoil
configuration.
The propeller blade 12 may include a front surface 20 and a rear surface (not
shown)
bounded by a leading edge 22, a trailing edge 24, and a tip edge 26, which
extends
between the leading edge 22 and the trailing edge 24.
[0010] The replaceable guard 14 may be selectively mountable to the
propeller blade
12 to cover at least the leading edge 22 of the propeller blade 12. In the
illustrated
example, the replaceable guard 14 covers the leading edge 22 and the tip edge
26.
Further, the replaceable guard 14 has been illustrated as being multi-
segmented although
this need not be the case. In the illustrated example, two of the multiple
segments are
used to cover most of the leading edge 22 while a third is used to cover the
tip edge 26.
Alternatively, in a multi-segmented configuration, a first segment may cover
the leading
edge 22 and a second segment may cover the tip edge 26. It is contemplated
that there
may not be a replaceable guard 14 on the trailing edge 24.
[0011] The multiple fasteners 16 may selectively couple the replaceable
guard 14 to
at least one of the front surface 20 and the rear surface (not shown). At
least one of the
multiple fasteners 16 will not extend beyond an exterior of the replaceable
guard 14. It is
contemplated that all of the multiple fasteners 16 will not extend beyond an
exterior of
the replaceable guard 14. In the illustrated example, multiple fasteners 16
operably
couple the replaceable guard 14 to both the front and rear surfaces of the
propeller blade
12. More specifically, the multiple fasteners 16 alternate between the front
and rear
surfaces along a length of the propeller blade 12. While no fasteners 16 have
been
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illustrated as attaching the replaceable guard 14 to the rear surface at the
tip edge 26 of
the propeller blade 12 it will be understood that fasteners 16 may attach the
replaceable
guard 14 to the rear surface at such a location.
[0012] Figure 3 illustrates one example of a portion of a propeller blade,
replaceable
guard, and fastener, which may be used in a propeller blade assembly including
the
propeller blade assembly 10. As the propeller blade 112, replaceable guard
114, and
fastener 116 are similar to those previously described, like parts will be
identified with
like numerals increased by 100, with it being understood that the description
of the like
parts of the propeller blade assembly 10 applies to the propeller blade
assembly having
the propeller blade 112, replaceable guard 114, and fastener 116, unless
otherwise noted.
[0013] As with the earlier described embodiment, the propeller blade 112
includes a
front surface 120 and a rear surface 118 as well as a leading edge (not
visible), a trailing
edge (not visible), and a tip edge 126. One difference is that the propeller
blade 112 is
illustrated as a composite body including a foam core 130, a carbon and glass
fiber layer
132, and a polyurethane layer 134. It will be understood that the propeller
blade 112 may
be formed in any suitable manner from any suitable material(s). Further, a
foam insert
136 has been illustrated as being located between a portion of the propeller
blade 112 and
the replaceable guard 114. An insert 140 may be bonded into a portion of the
propeller
blade 112 and sized to receive one of the multiple fasteners 116. In the
illustrated
example, a block 142 has been moulded within the propeller blade 112 and the
insert 140
is bonded into the block 142. The block 142 may be formed from a composite
such as a
glass fiber and insert moulded into the propeller blade 112.
[0014] By way of non-limiting example, the replaceable guard 114 has been
illustrated as including a backer layer 150 and an erosion protection rubber
layer 152. It
will be understood that the replaceable guard may be formed from any number of
layers
including a single layer. It will be further understood that the replaceable
guard may be
formed from any suitable material(s).
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[0015] In the illustrated example, only a single fastener 116 has been
illustrated;
however, multiple fasteners may be included and may operably couple the
replaceable
guard 114 to the front surface 120 and/or the rear surface 118 of the
propeller blade 112.
The fastener 116 is illustrated as including a rivet 160 selectively
receivable in the insert
140 and a washer 162. The replaceable guard 114 is clamped between the washer
162
and the insert 140 when the rivet 160 is received within the insert 140 and
the fastener
116 does not extend beyond an exterior 164 of the replaceable guard 114. By
way of
non-limiting example, Figure 4 illustrates the fastener 116 operably coupling
the
replaceable guard 114 to the rear surface 118.
[0016] Figure 5 illustrates an alternative propeller blade 212, a
replaceable guard 214,
and a fastener 216. As the propeller blade 212, replaceable guard 214, and
fastener 216
are similar to those previously described, like parts will be identified with
like numerals
increased by 100, with it being understood that the description of the like
parts of the
propeller blade assembly 10 and the propeller blade 112, replaceable guard
114, and
fastener 116 applies to the propeller blade assembly having the propeller
blade 212,
replaceable guard 214, and fastener 216, unless otherwise noted.
[0017] One difference is that the fastener 216 has been illustrated as
including a
screw 260 that is at least partially threaded and sized to be threaded into
the insert 240.
Another optional difference is that the insert 240 may be at least partially
threaded and
has been illustrated as being fully threaded. As with the previously described
embodiment the fastener 216 includes a washer 262 and when assembled, the
replaceable
guard 214 is clamped between the washer 262 and the insert 240 when the screw
260 is
threaded into the insert 240.
[0018] The embodiments described above provide for a variety of benefits
including
that the embodiments above allow for an erosion protection guard to attach to
at least a
leading edge of a propeller blade in a manner that enables speedy replacement
of an
eroded guard using simple tools without damaging the propeller blade. In this
manner,
multiple guard changes may be made without replacement of the propeller blade
and
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corrosion has no effect on its operation. In the above described embodiments,
removal of
the guard does not require any contact with the composite material of the
propeller blade.
Thus, the composite in the propeller blade will not be affected by guard
fitting and
removal. The internal insert spreads the clamping load of the rivet.
Further,
discontinuity with the airfoil is minimal as the fasteners are flush with or
do not extend
beyond an exterior of the replaceable guard. One contemporary design relies on
the use
of bolts with special nuts fitted from each side of a through bore in the
propeller blade.
The bolt heads and nuts extend above the guard and may corrode and erode
making it
difficult to remove them causing high replacement costs. In the above
described
embodiments, corrosion will have no effect and because the design is flush or
below the
guard erosion will be minimal.
[0019] To the
extent not already described, the different features and structures of the
various embodiments may be used in combination with each other as desired.
That one
feature may not be illustrated in all of the embodiments is not meant to be
construed that
it may not be, but is done for brevity of description. Thus, the various
features of the
different embodiments may be mixed and matched as desired to form new
embodiments,
whether or not the new embodiments are expressly described. All combinations
or
permutations of features described herein are covered by this disclosure.
[0020] While there
have been described herein what are considered to be preferred
and exemplary embodiments of the present invention, other modifications of
these
embodiments falling within the scope of the invention described herein shall
be apparent
to those skilled in the art.
