Note: Descriptions are shown in the official language in which they were submitted.
- CA 02209544 1997-07-03
DUAL DRIVE TRANSMISSION
CROSS REFERENCE TO RELATED APPLICATION
This application is related to Canadian
application File Number 2,184,553 filed August 30,
1996.
BACKGROUND OF THE INVENTION
Conventional clothes washing machines include an
agitator which oscillates during the washing cycle to
facilitate the cleaning of clothes. The oscillation of
the agitator is achieved through a series of linkages
and gears. More particularly, an input shaft is
connected to a drive motor and an output shaft is
connected to the agitator. An eccentric gear is driven
through an arcuate path by a series of gears connected
to the input shaft. The eccentric gear is operatively
connected to the output shaft, such that the rotary
motion from the input shaft is converted into the
oscillating motion of the agitator. The off-center
linkages require a counterweight for balance. The non-
alignment of the shafts produces undesirable side
loading on the shafts and gears. The off-center shafts
and counterbalance also necessitate a larger
transmission housing.
A substantially different washing machine
transmission is disclosed in U.S. patents 2,161,604 and
2,222,329 issued in the name of Watts. The watts
patents show opposing rack gears operatively connected
to coaxially aligned input and output shafts to convert
the rotary motion of the input shaft to an oscillation
motion for the output shaft and connected agitator in a
clothes washing machine. However, the devices
disclosed in the Watts patents are not believed to
have been ever commercialized due to a problem of
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binding between the rack gears and the output pinion. Such
binding necessarily resulted from the lack of radial or side-
to-side movement of the rack gears relative to the output
pinion.
Accordingly, a primary aspect of the present invention is
the provision of an improved dual drive transmission which
converts rotary movement to oscillating movement.
A further aspect of the present invention is the
provision of a dual drive transmission for a clothes washing
machine having a reduced size, without reducing load carrying
capabilities.
Another aspect of the present invention is the provision
of a dual drive transmission wherein the shafts are co-axially
aligned and the gears are equally spaced from the shaft axes.
A further aspect of the present invention is the
provision of a dual drive transmission wherein gear loading is
equalized.
Another aspect of the present invention is the provision
of rack gears which convert rotary motion to oscillating
motion without binding.
Still another aspect of the present invention is the
provision of an improved dual drive transmission normally
having pairs of opposite gears on opposite sides of the drive
shaft, and wherein the gears on one side of the shaft may be
removed to provide a single drive transmission for reduced
capacity machines having lesser power requirements.
A further aspect of the present invention is the
provision of an improved transmission having an anti-backup
mechanism.
These and other aspects will become apparent from the
following description of the invention.
SUMMARY OF THE INVENTION
The invention in one broad aspect provides a transmission
for converting a rotary input into an oscillating output,
comprising a housing having a removable cover, an input shaft
rotatably extending into the housing for inputting rotary
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motion to the transmission, an output shaft rotatably
extending into the cover for outputting oscillating motion, an
output pinion attached to the output shaft inside the housing
and gearing mounted between the input shaft and the output
shaft within the housing. The gearing includes at least one
rack gear positioned in mesh with the output pinion for
converting rotary motion from the input shaft into oscillatory
motion of the output shaft. The rack gear has opposite inner
and outer sides with gear teeth on the inner side.
In one embodiment a bushing is on the output shaft with
clearance therebetween such that the bushing is movable side-
to-side relative to the output shaft. The teeth of the rack
gear being movable side-to-side relative to the output pinion
to prevent binding between the rack gear and the output
pinion. The cover and the output shaft has clearance
therebetween to allow side-to-side movement of the output
pinion relative to the rack gear.
In another embodiment a bushing is pivotally mounted on
the output shaft between the output shaft and the cover, the
bushing being movable by a predetermined side-to-side distance
relative to the output shaft and a rack carrier is mounted on
the bushing for pivotal movement relative to the output shaft,
the rack carrier being in sliding engagement with the outer
side of the rack gear, the rack carrier retaining the rack
gear in mesh with the output pinion.
Still further the invention pertains to a method of
converting rotary motion to oscillating motion in a
transmission having a housing with a removable cover, an input
shaft journaled into the housing for inputting rotary motion
to the transmission, an output shaft journaled into the cover
for outputting oscillating motion, a bushing floatingly
journaled on the output shaft, an output gear attached to the
output shaft inside the housing, intermediate gearing between
the input and output shafts including a pair of rack gears
positioned on opposite sides of and in mesh with the output
gear for converting rotary motion from the input shaft into
oscillatory motion of the output shaft. The method comprises
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providing clearance between the bushing and the output shaft
to allow side-to-side movement of the bushing relative to the
output shaft, rotating the input shaft in one direction,
thereby oscillating the rack gears, the meshed output gear and
the output shaft, and equalizing the loading on each rack gear
by allowing the rack gears to move side-to-side relative to
the output gear by allowing the output shaft and output gear
to move side-to-side relative to one another while maintaining
meshing engagement between the rack gears and the output gear
to prevent binding between the rack gears and the output gear.
More particularly, a dual drive transmission is provided
to convert rotary action to oscillating action. The
transmission can be used on appliances, such as clothes
washing machines, wherein both rotary and oscillating action
are utilized during the wash cycle. The transmission includes
a housing having a removable cover. An input shaft is
journaled into the housing and provides rotary motion to the
transmission. An output shaft is journaled into the cover and
provides an oscillating motion to the agitator of the washer.
A series of gears are operatively mounted in meshing
combination between the input shaft and the output shaft
within the housing. The gearing includes an output pinion
attached to the output shaft and a pair of rack gears
positioned on opposite sides of and in mesh with the output
pinion. A rack carrier having an inverted U-shape has side
walls which slidably engage the outer sides of the rack gears
to retain the rack gears in mesh with the output pinion. The
rack carrier is mounted upon a floating bushing which is
pivotally mounted upon the output shaft, and is movable
side-to-side relative to the output shaft. The side-to-side
movement of the bushing allows the rack carrier and the rack
gears to move side-to-side relative to the output pinion,
thereby preventing binding between the rack gears and the
output pinion. Thus, loading on the rack gears is equalized.
DETAILED DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a washing machine.
Figure 2 is a sectional view taken along lines 2-2 of
Figure 1.
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Figure 3 is a sectional view taken along lines 3-3
of Figure 2.
Figure 4 is a sectional view taken along lines 4-4
of Figure 3, with the crank gears removed for clarity.
Figure 5 is a sectional view taken along lines 5-5
of Figure 3.
Figure 6 is a sectional view taken along lines 6-6
of Figure 4.
Figure 7 is a view similar to Figure 3 with the
rack gears and rack carrier removed for clarity.
Figures 8 and 9 are sectional views similar to
Figure 6 showing the rack gears at opposite ends of an
oscillating stroke.
Figure 10 is a perspective view of the underside
of the rack gears and rack carrier.
Figure 11 is a partial perspective exploded view
showing the rack carrier, the floating bushing, and the
output shaft.
Figure 12 is a perspective view of the anti-backup
mechanism of the present invention.
Figure 13 is a sectional view taken along lines
13-13 of Figure 4, and showing the anti-backup
mechanism of the present invention.
Figure 14 is a sectional view similar to Figure 6
showing an alternative embodiment single drive
transmission.
BRIEF DESCRIPTION OF THE DRAWINGS
A clothes washer is generally designated in the
drawings by the reference number 10. The washer 10
includes a cabinet 12 with an access opening 14 and a
door 16 movable between and open and closed positions
relative to the access opening 14. The washing machine
10 includes a vertical axis rotatable perforated basket
18 mounted within a tub 20. The tub 20 includes a
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drain outlet 22. An agitator 24 is operatively mounted
within the basket 18.
A transmission housing 26 and a brake housing 28
are mounted to the tub 20 by a plurality of braces 30.
A drive pulley 32 is operatively connected to the brake
within the brake housing 28 and to the drive train of
the transmission in the transmission housing 26. A
motor (not shown) is drivingly connected to the pulley
32 with a conventional drive belt (not shown).
The above-described components of the washing
machine 10 are conventional, and do not constitute a
part of the present invention.
The transmission housing 26 includes a lower
casing 34 and a removable upper cover 36. Preferably,
the cover 36 is threadably mounted upon the casing 34,
as seen in Figure 4. The transmission includes an
input shaft 38 and an output shaft 40. The input and
output shafts 38 and 40 are coaxially aligned. The
input shaft 38 extends rotatably into the lower
transmission casing 34 and is drivingly connected to
the pulley 32, which imparts rotational movement to the
input shaft 38. The output shaft 40 extends rotatably
through the transmission cover 36 and is drivingly
connected to the input shaft 38 through a series of
gears.
The gear train of the transmission includes an
input pinion 42 mounted upon the input shaft 38 for
rotation therewith. A pair of cluster gears 44 are
mounted on opposite sides of input pinion 42 and are in
meshing engagement with the input pinion, as best seen
in Figures 4 and 7. The cluster gears 44 are each
rotatably mounted upon a shaft 46 which is supported by
the lower transmission casing 34. Each of the cluster
gears 44 include an enlarged gear portion 48 and an
integrally formed reduced gear portion 50. The
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enlarged gear portion 48 of each cluster gear 44 is in
meshing combination with the input pinion 42.
The reduced gear portion 50 of each cluster gear
44 is in meshing engagement with a crank gear 52. The
crank gears 52 are rotatably mounted upon shafts 54
which extend upwardly from the lower transmission
casing 34 on opposite sides of the input shaft 38.
A pair of rack gears 56 are mounted on the crank
gears 52. Each rack gear 56 is connected to the
corresponding crank gear 52 by a pin 58 extending
downwardly from the rack gear and into a hole or
aperture 59 in the crank gear. The amount of offset of
aperture 59 from the centerline of crank gear 52
controls the degrees of oscillation of the output shaft
40. Each rack gear 56 includes a toothed inner side 60
and an untoothed outer side 62. The rack gears 58
extend on opposite sides of the output shaft 40, and
the toothed inner sides 60 are in meshing engagement
with an output pinion 64 mounted upon the output shaft
40.
The rack gears 56 are maintained in meshing
engagement with the output pinion 64 by a carrier 66.
The carrier 66 has an inverted U-shape in cross
section, as best seen in Figures 4 and 10. The carrier
66 has opposite side walls 68 which slidably engage the
outer sides 62 of the rack gears 56, as best seen in
Figures 4 and 6. The carrier 66 is mounted upon a
bushing 70, which in turn is rotatably mounted upon the
output shaft 40. As best seen in Figure 11, the
bushing 70 includes a trunk 72 with opposite tabs 74.
The trunk 72 is received within a central opening 76 of
the carrier 66, and the tabs 74 are matingly received
within slots or detents 78 in the carrier 66. As
further shown in Figure 11, the bushing 70 includes
slots 75 above the tabs 74. The slots 75 allow oil
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which is pumped up the output shaft 40 during operation
to be channeled onto the top of the carrier 66 and
returned to the lower portion of the transmission.
It is critical to the operation of the
transmission that the bushing 70 float or move side-to-
side with respect to the output shaft 40. As best seen
in Figure 3, there is a space 80 between the inner
diameter of the bushing 70 and the outer diameter of
the output shaft 40. Preferably, the difference
between the inner diameter of the bushing 70 and the
outside diameter of the output shaft 40 is at least
0.03". This space 80 permits the bushing 70, the
carrier 66, and the rack gears 56 to float or move
side-to-side relative to the output shaft 40 and the
output pinion 64 so as to equalize the load on the rack
gears 56. Thus, there is some play between the teeth
on the inner side 60 of the rack gears 56 and the teeth
of the output pinion 64. This floating movement of the
rack gears 56 relative to the output pinion 64 prevents
binding between the teeth and allows the transmission
to run smoothly. To further reduce misalignment and
binding between the pinion 64 and rack gears 56, the
lower end of the output shaft 40 is loosely journaled
into the removable upper cover 36 at bearing 39. In
the preferred embodiment, there is a nominal clearance
or space 41 of 0.0125 inch per side between the output
shaft 40 and the inner diameter of the bearing 39.
This clearance 41 allows the lower end of the output
shaft 40 and the output pinion 64 to move slightly from
side-to-side. It is also important that the centerline
of pins 58 and the pitch line of the teeth of the rack
gears 56 are aligned, as shown in Figure 6, so that
binding and misalignment during operation are
minimized.
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As seen in Figures 8 and 9, as the rack gears 56
oscillate back and forth along their longitudinal axes,
the rack gears 56 slide within the carrier 66. Also,
the rack gears 56 pivotally oscillate about the axis of
the output shaft 40, along with the carrier 66, via the
bushing 70. The oscillating movement of the rack gears
56 and the rotational movement of the carrier 66 are
shown in broken lines in Figures 8 and 9. More
particularly, with respect to Figure 8, as the crank
gear 52 rotates counterclockwise as indicated by arrows
82, the rack gears 56 and carrier 66 pivot
counterclockwise relative to the axis of the output
shaft as designated by arrow 84, and the rack gears 56
move along their axis, as designated by arrow 86, to
turn the output pinion 64 in a clockwise direction. As
the counterclockwise rotation of the crank gears 52
continues, as seen in Figure 9, the movement of the
rack gears 56 and carrier 60 reverses, so that the rack
gears 56 and carrier 60 will pivot in a clockwise
direction, as represented by arrow 88, relative to the
axis of the output shaft 40, and the rack gears 56 will
move outwardly along their longitudinal axes.
In the transmission there is a dual power path
from the input pinion 42 to the output pinion 64. The
dual power path is provided by identical pairs or sets
of cluster gears 44, crank gears 52 and rack gears 56
which are each directly opposed from each other or 180
degrees apart with respect to the vertical centerline
of the transmission. Because the pairs or sets of
gears 44, 52, and 56 are substantially identical on
both sides of the vertical centerline from input pinion
42 through the output pinion 64, there is equal loading
throughout the transmission on both sides of the
vertical centerline and substantially no side loading
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is introduced into either the input shaft 38 or output
shaft 40.
As seen in Figure 4, a cylindrical anti-backup
device 90 has a splined central bore 92 for mounting
the device upon the input shaft 38, which has
corresponding external splines for meshing with the
internal splines 92 of the device 90. The device also
includes a pair of radially outwardly projecting spring
fingers 94, as best seen in Figures 12 and 13. The
fingers 94 cooperate with substantially vertically
disposed stops or catches 96 on the internal side wall
of the transmission housing 26, as more fully described
below.
In operation, actuation of the motor (not shown)
in one direction turns the drive pulley 32 in a similar
direction. The drive pulley 32 in turn imparts
rotational movement to the input shaft 38, which
similarly rotates the input pinion 42. Rotation of the
input pinion 42 turns the cluster gears 44, which, in
turn, rotate the crank gears 52. As the crank gears 52
rotate, the interconnection with the rack gears 56 via
the rack gear pin 58 reciprocates the rack gears 56 in
opposite directions. The reciprocating movement of the
rack gears 56 imparts oscillating movement to the
output pinion 64, the connected output shaft 40, and
the agitator 24. Thus, rotational movement from the
input shaft 38 is converted to oscillating movement of
the output shaft 40 through the series of gears. As
the input shaft 38 rotates in a counterclockwise
direction, as seen in Figure 13, the fingers 94 of the
device 90 bias inwardly as the fingers pass over the
stops 96 on the transmission housing 26. Thus, the
device 90 rotates 360° within the housing 26.
As the load upon the rack gears 56 shifts or
changes, the floating bushing 70 allows the carrier 66
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and retained rack gears 56 to move side-to-side
relative to the output pinion 64 and output shaft 40
and the bearing 39 allows the lower end of the output
shaft 40 and the output pinion 64 to move slightly from
side-to-side, thereby equalizing the load forces and
preventing binding between the rack gears 56 and the
output pinion 64.
The agitator 24, which is connected to the output
shaft 40, thus oscillates upon actuation of the motor
in a first direction. When the drive motor is actuated
in the clockwise direction, as seen in Figure 13, the
brake (not shown) is disengaged and the terminal end 98
of the fingers 94 of the device 90 rotate a maximum of
180° and retentively engage the stops 96 on the
transmission housing 26 to allow the entire
transmission housing 26, the input shaft 38 and the
output shaft 40 to rotate in the same direction. Thus,
the basket 18 will rotate during the spin cycle of the
washing machine 10.
In an alternative embodiment, shown in Figure 14,
the gears on one-half of the input pinion 42 may be
removed to provide a single drive transmission for use
with a smaller machine having less power requirements.
More particularly, in the alternative embodiment, one
of each of the pairs of cluster gears 44, crank gears
52, and rack gears 56 are eliminated, all on the same
side of the input pinion 42. The rack carrier 66 is
still utilized, however, a tighter bushing similar to
bushing 70 is utilized to eliminate the float in the
remaining rack gear 56, and to maintain proper
engagement of the rack gear 56 with the output pinion
40. For example, the clearance between the single
drive bushing and the shaft is preferably 0.001-0.009
inch. The single drive transmission of the alternative
embodiment does not require any additional
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counterbalance weight, since the removed gears are
displaced by approximately the same weight of oil.
Whereas the invention has been shown and described
in connection with the preferred embodiments thereof,
it will be understood that many modifications,
substitutions, and additions may be made which are
within the intended broad scope of the following
claims. From the foregoing, it can be seen that the
present invention accomplishes at least all of the
stated objectives.
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