Note: Descriptions are shown in the official language in which they were submitted.
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BLOWER WHEEL ATTACHMENT FOR CLOTHES DRYER
Field of the Invention
The present invention relates to an appliance for drying clothing
articles, and, more particularly, to an improved attachment of the blower
wheel
to a drive motor shaft in a clothes dryer.
Background of the Invention
Clothes dryers used for drying articles of clothing typically have a
rotating drum into which the articles of clothing are inserted. The drum is
rotated by a motor and transmission interconnecting a shaft of the motor to
the drum. This transmission typically comprises a pulley attached to the shaft
of the motor and a belt entrained about the pulley and the drum. Heated air is
moved through the drum, as the drum is rotated, to dry the articles in the
drum. Air is moved through the drum by a blower wheel or centrifugal fan
that moves air through ducting typically located in the air exhaust for the
dryer
drum. The blower wheel is driven by connection with the shaft of the motor.
In a current blower wheel attachment, utilized in clothes dryers
manufactured by MABE Canada Inc., for attaching the blower wheel to the
shaft of the motor the shaft of the motor has a flat on its end portion that
extends through a central opening in the hub of the blower wheel. The blower
wheel also has a screw opening on the hub offset from the central opening of
the hub. A clip having an aperture with a matching flat is inserted over the
flat
of the motor shaft. The other end of the clip has a second opening through
which a screw passes into the screw opening in the hub of the centrifugal fan.
In this manner, the centrifugal fan is caused to rotate by the interconnection
of the hub and the flat of the shaft by the clip. Completing this
interconnection
is a labour intensive step during the manufacturing process of the clothes
dryer.
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U.S. patent 2,557,201 discloses a centrifugal fan in which a nut is
threaded onto a coupling socket that is in turn secured by a locating screw to
the shaft of a motor. The arrangement discloses an attachment that is also
relatively labour intensive.
U.S. 4,086,707 discloses a blower assembly where the radial or
centrifugal fan is secured to a motor shaft by a sleeve bearing, washer and a
lock washer fitted into a recess found on the end of the motor shaft. This
attachment requires numerous parts.
U.S. patent publication 2004/0221477 Al discloses a blower wheel
attachment to the shaft of a motor which incorporates a nut threaded onto the
end of the shaft of the motor. The attachment of this nut requires torquing
the
nut to the proper force so that the nut will not become disengaged during
normal operation.
Brief Description of the Invention
The present. invention relates to a blower wheel attachment for
attaching a centrifugal fan or a blower wheel to a threaded shaft end portion
of an electric motor used in a clothes dryer. In particular, the present
invention utilizes a nut that is held in place by the blower wheel so that the
nut
may be tightened to the shaft end portion as the motor rotates. The blower
wheel has a hub with a central opening surrounding a center axis of the
blower wheel. The blower wheel comprises at least one first wall portion
extending outwardly from the hub adjacent the central opening to at least
partially surround the center axis. The nut is simply inserted and then held
within the at least one first wall portion of the blower wheel so as to secure
the
nut to the threaded shaft end portion by simply rotating the fan relative to
the
shaft end portion. When the motor operates, due to the predetermined
orientation of the threads on the threaded shaft end portion, the nut is
torqued
sufficiently and is always tightened. As a result, the nut translates the
rotation
of the shaft into rotation of the fan.
In accordance with the invention there is provided a blower wheel
attachment comprising a blower wheel, an electric motor and a nut. The
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blower wheel comprises a plurality of radial fan blades and a hub having a
central opening surrounding a center axis of the blower wheel. The blower
wheel comprises at least one first wall portion extending outwardly from the
hub adjacent the central opening to at least partially surround the center
axis.
The electric motor has a shaft with a threaded shaft end portion extending
through the central opening and the at least one first wall portion. The
threaded shaft end portion has threads arranged in a predetermined
orientation. The nut is held within the at least one first wall portion and
secured to the threaded shaft end portion to cause the blower wheel to rotate
with the rotation of the shaft of the motor.
Brief Description of the Drawings
For a better understanding of the nature and objects of the present
invention reference may be had by way of example to the accompanying
diagrammatic drawings in which:
Figure 1 is a perspective view of an exemplary clothes dryer that may
benefit from the present invention; and,
Figure 2 is a front view of the blower wheel, central nut and motor
shaft;
Figure 3 is a sectional view of the blower wheel taken along lines A-A
of Figure 2;
Figure 4 is an enlarged partial sectional view of a hub portion of the
blower wheel, the nut and the threaded end portion of the motor shaft; and,
Figure 5 is a view of an alternative embodiment for the hub of the
centrifugal fan.
Detailed Description of the Invention
Figure 1 shows a perspective view of an exemplary clothes dryer 10
that may benefit frorn the present invention. The clothes dryer includes a
cabinet or a main housing 12 having a front panel 14, a rear panel 16, a pair
of side panels 18 and 20 spaced apart from each other by the front and rear
panels, a bottom panel 22, and a top cover 24. Within the housing 12 is a
drum or container 26 mounted for rotation around a substantially horizontal
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axis. A motor 44 rotates the drum 26 about the horizontal axis through, for
example, a pulley 43 and a belt 45. The drum 26 is generally cylindrical in
shape and has an imperforate outer cylindrical rear wall 28 and a front flange
or wall 30 defining an opening 32 to the drum. The front wall 30 and opening
32 are normally closed by a door (not shown). Clothing articles and other
fabrics are loaded into the drum 26 through the opening 32. A plurality of
tumbling ribs or baffles (not shown) are provided within the drum 26 to lift
the
articles and then allow them to tumble back to the bottom of the drum as the
drum rotates. The rear wall 28 is rotatably supported within the main housing
12 by a suitable fixed bearing. The rear wall 28 includes a plurality of holes
36 that receive hot air that has been heated by a heater such as a combustion
chamber 38 and a rear duct 40. The combustion chamber 38 receives
ambient air via an inlet 42. Although the exemplary clothes dryer 10 shown in
Figure 1 is a gas dryer, it could just as well be an electric dryer without
the
combustion chamber 38 and the rear duct 40. For an electric dryer, electrical
heating elements may be located in a heater housing between the rear panel
16 and the rear wall 28. The heated air is drawn from the drum 26 by a
blower wheel 48 which is also driven by the motor 44. The blower wheel 48
comprises an outer housing 52 and inner radial fan blades 54 adapted to
direct air about the periphery of the blower wheel. The air passes through a
screen filter 46 which traps any lint particles. As the air passes through the
screen filter 46, it enters a trap duct 49 and is moved by blower wheel 48 out
of the clothes dryer through an exhaust duct 50. After the clothing articles
have been dried, they are removed from the drum 26 via the opening 32.
An electronic interface and display panel 56 allows the user to program
operation of the dryer and further allows for monitoring progress of
respective
cycles of operation of the dryer.
Referring to F'igures 1 through 4 an embodiment of the present
invention is shown wherein the blower wheel 48 comprises centrifugal fan
blades 54 spaced frorn a hub 66 of the blower wheel 48. The hub 66 has a
central opening 68 that surrounds a center axis 70 for the blower wheel 48.
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The rotation of the blower wheel 48 and the shape of the fan blades 54 direct
air about the periphery of the blower wheel 48.
The blower wheel 48 has a first continuous wall portion 72 which is
shown in the shape of a hexagon. This first wall portion 72 extends outwardly
from the hub 66 adjacent the central opening 68 so as to surround the center
axis 70 of the blower wheel 48. As shown in Figures 2 and 3, a nut 80 is held
within the first wall portion 72. The nut 80 has a shape that corresponds to
the shape of the wall portion 72 (hexagonal shape). The nut 80 is held in the
embodiment shown by interference fit with the first wall portion 72. It should
be understood that a tight or loose interference fit may be employed and
further, joining of these two pieces such as by welding or cementing may form
an alternative embodiment. However, in the embodiment shown, the blower
wheel 48 comprises a plastic material and the hexagonal nut 80 further
comprises a metal, which dissimilar materials, do not readily lend themselves
to welding.
In the embodiment shown, the electric motor 44 has a shaft 74 which is
connected to the blower wheel 48 by the nut 80 (see Figure 4). It should be
understood that in an alternative embodiment, two electric motors may be
employed by the clothes dryer. One motor to drive the rotation of the rotating
drum 26 and the other motor to drive the blower wheel 48. The shaft 74 has a
threaded end portion 76 that extends through the central opening 68 of the
hub 66 and also extends into or through the first wall portion 72. The
threaded shaft end portion 76 has threads arranged in a pre-determined
orientation whereby the nut 80 is automatically tightened against the threads
of the shaft 74 by rotation of the shaft 74 during motor 44 operation. As a
result, the nut 80 is tightened on the threads of the threaded a shaft portion
76
during initial rotation of the shaft 74 and the nut 80 thereafter causes the
blower wheel 48 to rotate with the rotation of the shaft 24 during motor 44
operation.
As best seen in Figure 4, the shaft 74 has an intermediate portion 82 of
diameter larger than the threaded shaft end portion 76. As a result shoulder
84 is located between the intermediate portion 82 and the threaded shaft end
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portion 76. The blower wheel 48 further comprises at least one second wall
portion 90 extending from the hub 66 adjacent the central opening 68 on a
side of a blower wheel 48 opposite to that side supporting the first wall
portion
72. Consequently, the second wall portion 90 together with the hub 66
provides a seat in which the shoulder 84 and the intermediate portion 82 of
the shaft 74 may engage as the nut 80 is tightened against the threaded shaft
end portion 76.
Referring to Figure 5, there is shown an alternative embodiment for the
first wall portion 72. In this embodiment the first wall portion 72 is
discontinuous and comprises two wall portions 72A and 72B. It should be
understood that in an alternative embodiment multiple wall portions may be
arranged so that they become a series of spaced apart ribs extending around
the central opening 68 from the hub 66. The purpose of the first wall portion
72 or the at least one first wall portion 72 shown in Figure 5 remains the
same
namely to hold the nut 80 within the wall portions 72A and 72B. Also, it
should be understood that the second wall portion 90 shown in Figure 4 may
also be discontinuous and thereby comprise multiple wall portions.
While the invention has been described in terms of various specific
embodiments, those skilled in the art will recognize that the invention can be
practiced with modifications within the spirit and scope of the present
invention as disclosed herein.
