Note: Descriptions are shown in the official language in which they were submitted.
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DRIVE SYSTEM
BACKGROUND OF THE INVENTION
The invention relates to drive systems for self-
propelled wheeled appliances, and more particularly to
a power assisted vacuum cleaner.
Handle manipulated self-mobilized wheeled applian-
ces such as vacuum cleaners, sweepers, lawn mowers and
carts are well known. U.S. Patents 3,618,687 to Ripple
et al., 4,249,281 to Meyer et al., 4,347,643 to Bair III
and 4,434,865 to Tschudy et al., for example, illustrate
transmissions for vacuum cleaners.
Known drive systems for these and like appliances
can have one or more disadvantages of limited power
capacity, inadequate speed ranges, low durability, noisy
operation, limited speed reduction ratio necessitating
relatively small traction wheels, expensive componentry
and/or non-uniform response and power application.
SDMMARY OF THE INVENTION
The invention provides a transmission assembly for
a handle controlled wheeled appliance that has a high
power output capacity, is durable and quiet in use and
which delivers smooth application of power in both
forward and reverse directions. The disclosed transmis-
sion arrangement includes a first stage of speed
reduction in the coupling of a drive motor and a
transmission input shaft interconnected by sprockets and
a primary drive belt. A pinion on the input shaft
drives one of a pair of meshed counter-rotating gears.
A clutch/sprocket is associated with each of the
counter-rotating gears and a belt couples both of these
clutch/sprockets to a common sprocket which through
associated elements drives the wheels of the appliance.
The input pinion, counter-rotating gears, respective
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2
clutch/sprockets and common output sprocket all rotate
about axes parallel to the motor shaft. An actuating
mechanism selectively energizes one or the other of the
clutch/sprockets for forward or reverse propulsion of
the appliance.
The disclosed drive system is particularly suited
for use in a vacuum cleaner where it is driven off the
shaft of the fan motor. The transmission provides a
relatively high speed reduction ratio to readily
accommodate the characteristically high speed of the fan
motor and provide a wheel shaft output speed that makes
practical the use of relatively large traction wheels.
Such large traction wheels afford improved operation
over a variety of floor surfaces.
The actuating mechanism of the transmission is
connected to the upright handle of the cleaner and
allows the appliance to respond to moderate pushing or
pulling forces applied to the handle by the user to
initiate, respectively, forward and reverse propulsion.
Moreover, the speed at which the cleaner is driven is
proportional to force applied to handle by user, in both
forward and reverse directions.
The disclosed actuating mechanism and clutching
elements provide a smooth application of power in either
the forward or reverse directions and this response is
generally unaffected by wear over long periods of use.
Each of the clutch/sprockets includes an enlarged flange
that affords a correspondingly large friction surface
and a central bore that receives an associated biasing
spring and thereby contributes to a savings in the size
of the transmission.
An additional feature of the disclosed transmission
is a wheel shaft bearing construction which serves to
locate the case of the transmission relative to the
housing body of the appliance and which serves to
support the weight of the appliance on the wheel shaft
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3
without imposing this weight or shock loads on the
transmission itself.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a vacuum cleaner
constructed in accordance with the present invention;
Figure 2 is a simplified partial cross-sectional
view taken in a vertical plane through the housing of
the vacuum cleaner;
Figure 3 is a rear perspective view of a transmis-
sion constructed in accordance with the invention in
exploded relation to a portion of the housing of the
vacuum cleaner;
Figure 4 is a cross-sectional view of the transmis-
sion taken in a horizontal plane indicated by the line
4-4 in Figure 5;
Figure 5 is a cross-sectional view of the transmis-
sion taken in a central vertical plane;
Figure 6 is a schematic cross-sectional view of the
transmission taken in the staggered plane indicated by
the lines 6-6 in Figure 4;
Figure 7 is a rear view, partially in section, of
the transmission and associated parts;
Figure 8 is a fragmentary cross-sectional view on a
enlarged scale of a portable handle installed on the
housing and interlocked with elements to prevent
energization of the transmission;
Figure 9 is a cross-sectional view of a carriage on
the housing for mounting the upright or portable handles
of the vacuum cleaner;
Figure 10 is an enlarged view of a typical gear and
clutch/sprocket set of the transmission;
Figure 11 is an end view of a wheel shaft bearing
of the transmission;
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4
Figure 12 is a vertical cross-sectional view of the
wheel shaft bearing of the transmission taken in the
plane indicated by the line 12-12 of Figure 11;
Figure 13 is a cross-sectional view of the wheel
shaft bearing taken in the vertical plane indicated by
the line 13-13 of Figure 11;
Figure 14 is an end view of the wheel shaft bearing
opposite the view of Figure 11;
Figure 15 is a somewhat schematic perspective view
of a foot pedal mechanism for controlling drive from the
transmission to the wheel shaft and illustrating the
mechanism in a power transmitting position; and
Figure 16 is a view similar to Figure 15 but
showing the pedal mechanism in a neutral position.
DESCRIPTION OF THE PREFERRED EIiBODIME<~1T
Figure 1 illustrates a vacuum cleaner 10 including
a housing 11, a bag 12 for collecting dirt and a handle
13 for manipulating the appliance across a floor
surface. The cleaner 10 is supported on relatively
small front wheels 14 and relatively large rear traction
wheels 16. As shown in Figure 2, an electric motor 17
is enclosed within the housing il and has a shaft 18
which, in the illustrated arrangement, is generally
horizontal and parallel to the front-to-rear direction
of the cleaner 10. On a front end of the motor shaft 18
there is a suction fan 19. The shaft 18 includes an
extension 21 extending forwardly of the fan. In use a
belt (not shown) engages the extension 21, driving a
rotary agitator brush in a generally conventional manner.
A grooved sprocket 22 is fixed on a rear end of the
motor shaft 18 and is coupled to a similar grooved
sprocket 23 by a toothed belt 24. These sprockets 22,
23 and belt 24 provide the primary drive from the motor
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17 to a transmission 26 that drives the rear traction
wheels 16 from motive power derived from the motor.
In the illustrated embodiment, the transmission 26
is a self-contained modular unit as illustrated in
5 Figure 3 and includes a casing 27 split in front and
rear sections mating at a vertical plane indicated at 28
in Figure 5. The sprocket 23 is carried on an input
shaft 29 of the transmission. Within the casing 27 are
various power transmitting elements that reduce the
speed of the motor shaft and selectively provide forward
and rearward rotary shaft output. These elements within
the casing 27 all rotate about axes parallel to the axis
of the motor shaft 18. More specifically, the input
shaft 29 has fixed to it a pinion gear 31. The input
shaft 29 rotates in a suitable bearing in a boss 30 of
the front section of the casing 27 (Figure 6). Meshed
with the pinion gear 31 is a gear 33 which meshes with a
substantially identical counter-rotating gear 34. The
gears 33, 34 spin on cylindrical bearings 38 assembled
on respective non-rotating shafts 36.
With reference to Figure 10, each gear has an
annulus of friction facing material 37 suitably fixed to
a radial face thereof. A thrust bearing assembly 39 is
associated with each gear 33, 34. Each thrust bearing
assembly 39 is of an anti-friction type, generally
commercially available, which comprises a plurality of
radially oriented rollers circumferentially spaced about
the axis of the shaft between a pair of annular flat
races. A flat annular pocket or recess 41 in a rear
face of each gear 33, 34 receives the associated thrust
bearing assembly 39 with a press fit.
A pair of clutch/sprocket members are provided.
Each clutch/sprocket member 46 is associated with a
corresponding one of the gears 33, 34. The
clutch/sprocket members 46 are transmission output
elements and are essentially identical and each is
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6
disposed in confronting relation to the respective
clutch facing or plate 37. Each clutch/sprocket 46 is
journaled on the associated shaft 36 by anti-friction
bearing 47. A pair of the anti-friction thrust bearing
assemblies 48 are provided. Each bearing like the
bearings 39, is interposed between an associated one of
the clutch/sprockets 46 and an associated wall area of
the casing 27.
Each clutch/sprocket 46 includes a radially
extending round flange 49 having an annular clutching
surface 51 lying in a radial plane. The flange 49 forms
the major diameter of the clutch/sprocket member and
only a fraction of the axial length of the member 46.
An axial bore 52 through the clutch/sprocket member 46
is stepped in diameter to provide successive counter-
bores 53, 54 and a clearance bore 56 for the shaft 36.
Between the counterbores 53 and 54 is a radial surface
57 and, similarly, between the bores 54, 56 is a radial
surface 58.
At a generally round exterior mid-zone 61, the
clutch/sprocket 46 has uniformly spaced axially
extending grooves 62 that cooperate with teeth in a
drive belt 63. At an end remote from the flange 49,
each clutch/sprocket member 46 has a cylindrical pilot
surface 64 concentric with the axis of the bore 52 and
adapted to support the thrust bearing assembly 48 which
is assembled thereon. Each clutch/sprocket member has a
radial shoulder 66 which engages a race of the as-
sociated thrust bearing assembly 48. Each shoulder 66
is disposed a predetermined distance from an end 67 of
its clutch/sprocket member 46 which distance is less
than the axial thickness of the bearing 48 so that the
bearing will prevent member contact with an adjacent
wall area of the casing 27.
Each counterbore 54 is proportioned to receive its
associated bearing 47. It will be seen that each
7 2029256
bearing 47 is in the same axial zone as the grooved mid-
zone 61 that receives the belt 63. Each counterbore 53
is proportioned to receive an associated one of a pair
of biasing compression springs 68 with the axial depth
of this counterbore extending substantially to the zone
surrounded by the grooved exterior 61.
As indicated in Figure 10, each spring 68 bears
against its associated radial surface or shoulder 57 at
one end and at the other end against a race of its
bearing assembly 38. Each spring 68 is dimensioned to
bias the associated friction facing material 37 away
from its clutching surface 51. Each gear 33 or 34 has a
hub portion 69 which surrounds its counterbore 53. Each
hub portion 69 has an exterior diameter somewhat larger
than its associated grooved area 61. Each flange 49 has
a diameter that is approximately twice that of the
associated grooved section 61 and a length that is
generally less than the grooved section. Preferably,
the clutch/sprocket 46 is formed of a heat dissipating
material such as aluminum so that it can conduct
friction created heat away from the clutching surface
51.
As best shown in Figures 5 and 6, a sprocket/gear
unit 71 is journaled by a bearing 72 on a shaft 73.
The axis of the shaft 73 is in an imaginary vertical
plane midway between the shafts 36. The sprocket/gear
unit 71 has an annular radially outer sprocket rim part
74 that includes grooves on its outer periphery which
mesh with the teeth of the belt 63. An inner periphery
of the rim 74 is fixed as by a spline on the outer
periphery of a bevel gear part 76 of the unit 71. A
side of the rim 74 forms a hollow 77 and teeth of the
bevel gear 76 are situated within this hollow.
A bevel gear 81 (Fig. 7) is in constant mesh with
the bevel gear part 76 and is carried for rotation on a
horizontal wheel shaft 82. The axis of the wheel shaft
202 925fi
82 is transverse to the axes of the previously described
sprockets or pulleys and gears of the transmission 26.
The rear traction wheels 16 are respectively mounted on
end portions of the shaft 82 and keyed to prevent
relative rotation. Also assembled on the wheel shaft 82
is a torque limiting coupling body 83, a compression
spring 84 and opposed thrust bearings 86. The thrust
bearings 86 are located by and bear against webs 87
formed on the transmission casing 27. The coupling body
83 is keyed to the shaft 82 by a cross pin 88 pressed in
a hole in the shaft and received in an axially extending
slot 89 in the side wall of the body 83. The bevel gear
81 and coupling body 83 have teeth at 90, 91 with
surfaces that interengage in helical planes in a known
manner.
Under ordinary circumstances, the spring 84
maintains the teeth 90, 91 interengaged so that the
bevel gear 81 can apply a driving torque to the wheel
shaft 82. However, when torque becomes excessive the
compression spring yields to allow teeth 90, 91 to
disengage and thereby decouple the bevel gear 81 from
the wheel shaft 82 so that these later elements can
rotate relative to one another. Limited axial movement
of the coupling body 83 on the shaft 82 is permitted by
the cross pin 88 and slot 89 while relative rotation
between the shaft and body is precluded.
Bearings 92 on opposite sides of the casing 27
rotatably support the wheel shaft 82. The bearings 92,
which are substantially identical, are shown in detail
in Figures 11-14 inclusive. The bearings are preferably
molded of a suitable self-lubricating material such as
the thermoplastic material marketed by E. I. Dupont
DeNemours & Co. under the trademark DELRIN AF.
As best seen in Fig. 12, each bearing 92 has a
generally cylindrical tubular body 93 and an integral
trapezoidal flange section 94. A cylindrical bore 95
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9
runs through the body 93 along an axis perpendicular to
the plane of the trapezoidal flange section 94. The
trapezoidal flange 94 is generally symmetrical about an
imaginary vertical plane 96 in which the axis of the
bore 95 lies. Opposite edges 97 of the trapezoidal
flange 94 converge towards one another with reference to
a direction of increasing distance above the axis of the
bore 95 and diverge from one another in a direction of
increasing distance below this bore axis. These non-
parallel edges or surfaces 97 lie, preferably, in planes
perpendicular to the planes of Figures 11 and 14. It is
seen that the width of the trapezoidal flange 94 is
smaller adjacent its top than at its bottom.
At a top edge 101 of the trapezoidal flange 94,
there exists a lip or tab 102 which extends upwardly
above the plane of such edge. With directional
reference to the bore 95, the axial length of the lip
102 is somewhat limited and preferably is less than 1/2
the axial thickness of the trapezoidal flange section
94. An outer face 104 of the trapezoidal flange 94 is
spaced inwardly from one end 106 of the tubular body 93.
An inside face 103 of the flange 94 has a plurality of
recesses 107 and integral stiffening ribs 108 that
result in a part of generally uniform wall thickness
which can be readily injection molded and which exhibits
high mechanical strength.
As shown in Fig. 3, brackets 109 screwed to the
casing 27 retain the bearings 92 in place with respect
to the casing. Each bearing 92 is received in an as-
sociated one of a pair of slots 111 formed in a base
section 112 of the vacuum cleaner housing 11. The
transmission casing 27 is mounted on this base section
112 and retained thereon by suitable screws. The
configuration of each slot 111 is complementary to the
shape of its bearing 92 such that its edges wedge
snugly against the corresponding edges 97 of its bearing
l0 2029256
flange 94. The transmission casing 27 is secured to
the lower housing section 112 by screws assembled
through holes 113 (Figure 4) in horizontal flanges of
the casing and aligned with threaded holes (not shown)
in the section 112.
As the transmission casing 27 is drawn into
assembled position, the bearings 92, through interaction
with the surfaces of the slots 111, align themselves
with the housing 112. The lips 102 fit inside the wall
l0 of the housing section 112 as indicated in Figure 7
where the housing section is indicated in phantom. The
lips 102 axially locate the bearings 92 with respect to
the housing 112.
An actuator lever 116 is universally mounted in a
spherical socket 117 integrally formed on a back wall of
the casing 27. The lever 116 has a complementary
spherical boss 118 that fits into the socket 117. A
screw 119 extends through the axes of the socket 117 and
boss 118 and retains the lever 116 with adequate
clearance to allow limited pivotal movement of the lever
on the casing 27. As shown in part in Figure 3 and
fragmentarily in Figure 10, pins 121 integrally formed
on the lever 116 at its four corners, project through
associated holes 122 in the rear wall of the casing 27.
The pins 121 operate in pairs with the pins on the right
in Figure 7 contacting the stationary race of the
associated thrust bearing assembly 39 at diametrically
opposed points equidistant from its center. Similarly,
the pins 121 on the left contact the race of the other
thrust bearing 39.
A spherical projection 123 on the lever is coupled
in a complementary socket of a horizontal link 124,
Figure 3. The link 124 at is opposite end is pivotally
pinned at 126 to a vertical lever 127. At its lower end
128, the vertical lever 127 is pivotally pinned to a
boss 129 on the casing 27, Figure 2. An upper end 131
CA 02029256 2001-05-22
11
of the lever 127 is forked or slotted to receive a pin 132 fixed
to a bracket 133 that, in turn, is fixed to a handle support
carriage 134 (Figures 8 and 9).
The carriage 136 rides in a linear bearing assembly 136
rigidly mounted just inside the upper side of the housing 11.
The linear bearing assembly 136 comprises a plurality of
cylindrical rollers 137 in opposed V-shaped configurations that
restrain the carriage 134for translatory movement in a
substantially horizontal plane.
The carriage 134 carries a pivot assembly 138that supports
the upright handle l3for pivotal movement about a horizontal
axis parallel to the wheel shaft 82. Alternatively, the pivot
assembly 138 cooperates with a substitute handle 139 as is
discussed more fully herein below and as is disclosed in U.S.
Patent No. 4,947,512, filed December 9, 1988.
Pushing and pulling forces exerted on the handle 13 by the
user energize the transmission 26 to provide power assist for
propelling the cleaner 10 over a floor surface being cleaned. A
pushing force on the :handle 13 results in a limited forward
displacement of the carriage 134 within the housing 11. Movement
of the carriage 134 ins transferred by the lever 127 and link 124
to a forward displacement of the left end of the actuating lever
116 as viewed in Figure 7. The pins 121 on the left of the pivot
screw 119 press again;~t the associated thrust bearing 39 causing
slight axial displacement of such thrust bearing and the
associated gear 34. Tlzis movement brings the associated friction
facing material 37 into engagement with the associated
clutch/sprocket member 46, causing this clutch/sprocket member
to adopt the rotation of the gear 34. The belt 63 causes the
sprocket/gear 71 to rotate in a like direction. The bevel gear
76 cooperating with the wheel
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12
shaft bevel gear 81 converts this rotation into rotation
of the wheel shaft 82 in a forward direction.
When the handle 13 is pulled, the pins 121 on the
right Figure 7 are effective to cause powered rotation
of the other clutch/sprocket member 46 associated with
the gear 31. Since this rotation is opposite that of
the gear 34, the wheel shaft is driven in a reverse
direction by means of the associated clutch/sprocket
member 46, belt 63, sprocket/gear 71 and bevel gear 81.
Figures 15 and 16 illustrate a foot pedal operated
mechanism 146 which selectively shifts the coupling body
83 from its normally engaged power transmitting position
to a neutral position where the wheel shaft 82 is free
of a positive torque transmitting connection with the
transmission 26. A foot pedal 147 of the mechanism 146
is exposed at a lower rear side of the housing 11; the
mechanism 146 is not shown in Figure 3 so that other
parts can be clearly seen. The mechanism 146 includes a
bell crank 148 with arms 149 and 151 pivotal about a
vertical pin 152 that is fixed to a lower surface of the
transmission casing 27. One of the arms 149 is received
in a peripheral groove 153 in the coupling body 83. The
other arm 151 has a cam follower tab 154 which is
engaged by a barrel cam segment 156. The cam segment
156 is fixed to a horizontal shaft 157 that pivots in a
block 158 fixed on the casing 27. The horizontal shaft
157 projects rearwardly beyond the housing 11 and the
pedal 147 is fixed to its outer or rearward end. The
cam segment 156 includes two flat areas 159, 161 and an
intermediate shifting area 162.
By stepping on the right side of the pedal 147 (as
viewed in Figures 15 and 16) the user can manually
engage the transmission 26. In this condition, the
flat area 159 of the cam 156 allows the follower tab 154
to assume a position where the bell crank arm 149
permits the spring 84 to normally press the coupler body
~x.'~ ;fro
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13
teeth 91 into interengagement with the bevel gear teeth
90. When the left side of the pedal 147 is manually
depressed, the cam 156 rocks and the follower tab 154
slides across the shifting area 162 to the flat area
161. In this condition, shown in Figure 16, the
follower tab 154 forces the bell crank arm 149 to the
right to move the coupler body 83 against the spring 84
and the teeth 90, 91 out of engagement leaving the
transmission in a neutral state where there is no active
rotary connection between it and the wheel shaft 82.
The flat areas 159, 161 are oriented so that they each
support the follower tab 154 in a stable or self-
maintaining position.
The biasing springs 68 associated with the
clutch/sprocket members 46 are calibrated to provide a
desired resistance against energization of their
respective clutch elements. Their spring rates and
state of pre-compression in assembly will ordinarily be
different from one another so that a preferred response
of the transmission to manual pushing effort and,
alternatively, manual pulling effort on the handle can
be selected for a good user feel. It will be understood
that the disclosed linkage and actuating kinematics are
such that with appropriate selection of the springs 68
the pushing force required to develop forward clutch
engaging action is independent of that required for
pulling force for reversing and vice versa. It will
also be understood that the various linkage and
clutching elements are free to significant sensitivity
to wear so that the feel and response of the cleaner to
the user remains constant throughout the life of the
product.
With reference to Figure 8, when it is desired to
operate the cleaner 10 in a portable mode and rotation
of the rear traction wheels 16 is to be avoided, the
substitute portable handle 139 is used. This handle 139
14 2029256
has a blade 141 which engages the pivot assembly 138 and
has a socket 142 which closely engages a head of a screw
143 fixed to the housing 11. The handle 139 thus locks
the pivot assembly 138 and therefore the carriage 134
against horizontal movement. This locking action
prevents the linkage elements 127 and 124 from energiz-
ing the transmission.
It should be evident that this disclosure is by way
of example and that various changes may be made by
adding, modifying or eliminating details without
departing from the fair scope of the teaching contained
in this disclosure. The invention is therefore not
limited to particular details of this disclosure except
to the extent that the following claims are necessarily
so limited.
