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Патент USA US3088313

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May 7, 1963
E. SCHMETTOW
3,088,303
AUTOMATIC WASHING MACHINE HAVING A VARIABLE SPEED DRIVE
Filed Sept. 19, 1961
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May 7, 1963
E. SCHMETTOW
3,088,303
AUTOMATIC WASHING MACHINE HAVING A VARIABLE SPEED DRIVE
Filed Sept. 19. 1961
7600 -
7200 —
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4 Sheets-Sheet 2
May 7, 1963
E. SCHMETTOW
3,088,303
AUTOMATIC WASHING MACHINE HAVING A VARIABLE SPEED DRIVE
Filed Sept. 19, 1961
4 Sheets-Sheet 3
May 7, 1963
E. SCHMETTOW
-
3,088,303
AUTOMATIC WASHING MACHINE HAVING A VARIABLE SPEED DRIVE
Filed Sept. 19, 1961
4 Sheets-Sheet 4
3,988,393
Unite States Patent
Patented May 7, 1963
2
1
sion mechanism whose transmission ratio is continuously
controllable from a lower ‘to an upper limit value, in
combination with a speed-responsive regulating means
which preferably under direct or indirect control by the
3,088,303
AUTUMATIC WASHING MACHINE HAVING A
VARIABLE SPEED DRIVE
Erich Schmettow, Hohenbrunn-Riemeriing, Germany, as
signor to Siemens-Electrogerate Aktiengesellschart,
programming or other control device of the washing
machine, automatically increase the drum speed up to
Berlin, Germany, a corporation of Germany
Filed Sept. 19, 1961, Ser. No. 139,584
Claims priority, application Germany Sept. 23, 1960
6 Claims. (Cl. 68-12)
the desired high spinning speed. The transmission mech—
anism thus automatically controlled then operates con
strainedly to always maintain the drive motor at a favor
10
My invention relates to drum-type washing machines,
able point of its torque characteristic while the speed of
the drum is being built up to the spin-drying value.
Such a washing-machine drive can readily be so de
particularly to automatic electric washers, in which a
signed that it will automatically return to washing speed
laundry-receiving drum is driven from an electric motor
in the event the drive motor is subjected to voltage failure.
for slow rotation of the drum during washing and rinsing
According to a more speci?c feature of my invention,
15
and fast rotation during subsequent spin-drying.
the above-mentioned control and resetting operations are
Such di?erent rotating speeds of the drum can be ob
obtained by providing the ratio-regulating means of the
tained and exclusively controlled with the aid of -multi—
transmission with a centrifugal device, such as a weight
stage mechanical speed-change transmissions, but such
movable in dependence upon centrifugal force, for con
transmissions occupy much space and represent an ex
tinuously varying the drum-speed. Such a centrifugally
pensive component it three or more transmission rat1os
regulated transmission is automatically effective to in
are required. The expenditure in material and space
crease the drum speed up to the desired maximum value
increases considerably with the ratio of ‘the required
at the beginning of a spin-drying operation and also sets
maximum (spinning) and minimum (washing) speeds.
the transmission mechanism back to low speed in the
For good spin-drying, however, the spinning speed must
event of voltage failure.
be kept as high as feasible, Whereas the washing speed
According to a particularly simple embodiment of the
for best laundering must have a much lower value,
invention, the electric drive motor of the washing machine
usually at about 50 rpm. Since furthermore the elec
always operates at a ?xed speed and the speed change
tric motors preferably employed for washing machines
of the drum is effected exclusively by the change in trans
are of the squirrel-cage type, because they are not suscep
tible to trouble by sparking and require virtually no main 3O mission ratio within the transmission mechanism con
necting the motor with the drum.
tenance, and since such motors have ‘a poor starting
characteristic, namely a low torque at low speed and
hence very low starting power, the design of a drive for
drum-type washers employing such motors involves con
siderable difficulties which, as a rule, can be overcome
However, according to another, preferred feature of
my invention, a considerable further improvement is
achieved by providing for the input member of the regu
latable transmission mechanism two selective speed steps,
a lower speed to be effective during washing operation
and a higher speed to be effective for spin-drying opera
tion, the transmission mechanism having a ?xed trans
mission ratio at the lower speed of its input member ‘and
only with heavy, large and expensive motors and/or
with the aid of large and complicated transmission mech
anisms. Another possibility of adjusting different driv
ing speeds resides in the use of a pole-switchable squirrel
cage motor.
commencing its ratio-changing operation only when the
However, in order to obtain the above
speed of the input member is switched to the higher
value. This combination of the variable-ratio transmis
sion with a two—step primary drive affords covering a
mentioned extreme change in transmission ratio between
washing and spinning speeds, the necessary motors would
have to have a very high pole-number ratio, for example
2:24 or more.
Such motors are excessively heavy and
expensive.
It is therefore an object of my invention, relating to
automatic drum-type washing machines of the type de
scribed above, to devise a drive which permits using
a relatively small electric motor in both stages of opera
tion, namely for slow washing operation as well as for
fast spin—drying, while securing an economical perform
45
particularly great range of speeds with relatively simple
means.
According to a more speci?c feature of the type just
mentioned, the change between the two steps of input
speed for the variable-ratio transmission is effected by
means of a two-stage speed-change gearing between a
single-speed electric motor and the input member of the
transmission mechanism. In such a machine, it is prefer
able to control the two-stage gear transmission by a con
trol pulse supplied from the programming or control de
with a highest feasible torque of the drive m otor.
Another object of my invention is to devise a drive for 55 vice of the washing machine, namely so that when this
device switches the machine from washing to spinning,
such washing machines which, in the event the operating
ance and obtaining a transition from washing to spinning
voltage should fail during the spinning operation, will
automatically and without appreciable auxiliary devices,
return into an operating condition in which the drive
can readily commence with a new operating process.
That is, the washing machine when operating in dry
spinning operation and then encountering voltage fail
ure is supposed to return with particularly simple means
the gear transmission is simultaneously switched from
low gear to high gear, the regulator of the continuously
variable transmission mechanism being so set that it
responds to the switching to increased primary driving
speed, thus commencing the above-described automatic
increase of the drum speed up to the desired spinning
speed.
According to another, alternative feature of my inven
which, as to drum speed, either corresponds to the wash— 65 tion, the change in input speed applied to the input mem
ber ‘of the variable-ratio transmission mechanism is ef
ing stage or approaches it suf?ciently to permit restart
fected by providing the machine with a pole-switchable
ing the motor with a sufdcient starting torque until the
and in a reliable manner into an operating condition
speed is automatically increased again up to the spinning
induction motor which in this case may have a relatively
simple design because its pole number ratio need only be
value.
To achieve these objects and in accordance with a 70 moderate, for example 2:4, as the further increase in
drum speed is effected by the variable transmission be
feature of my invention, I provide the drum-type wash
tween motor and drum.
ing machine between the electric drive motor and the
According to a further feature of my invention, the
laundry-receiving drum with a variable-speed transmis
3,088,303
5
above-mentioned variable-ratio transmission comprises
an endless V-belt with belt sheaves of adjustable effec
tive diameter, belt transmission of this type being gener
ally known as such. The diameter-changing control of
one or both belt sheaves can then be effected directly by
the centrifugal regulator cooperating with a counter
spring. When providing two adjustable belt sheaves, it is
mission, a pole-switchable, drive motor and a program
control device.
FIG. 2 shows schematically in a substantially similar
manner a washing machine with a single-speed motor
and a two-stage speed-change gear interposed between
the motor and the variable-ratio transmission.
FIG. 3 shows schematically a side view of part of
preferable to mount the spring, to oppose the centrifugal
FIG. 1 or 2.
force, upon the displaceable portion of one of the sheaves
FIG. 4 shows a side view similar to FIG. 3 but relating
and to mount the centrifugal weights upon the displace 10 to a somewhat modi?ed design.
able portion of the other sheave. In this manner, the
FIGS. 5a and 5b illustrate in section the upper and
spring and the pro-tension produced thereby have the
lower belt sheaves respectively of the variable-ratio trans
effect of determining the rotating speed at which the
mission according to FIGS. 1 to 4, each illustration show
centrifugal regulator will commence operating, and the
ing two different operating positions.
same spring then simultaneously serves to maintain sub 15
FIG. 6 is a speed-time diagram explanatory of the per
stantially uniform tension in the belt.
formance of machines according to the invention.
Such a V-belt transmission in a washing machine ac
FIG. 7 shows in section a two-stage belt transmission
cording to the invention may also be ‘of the two-stage
of variable ratio applicable in washing machines other
type. In this case, an intermediate shaft is provided be
wise corresponding to those of the preceding embodi
tween the motor shaft and the drum shaft. The inter 20 ments; and
mediate shaft is preferably provided vvith two belt-sheave
FIG. 8 is an explanatory diagram- relating to the per
portions which are ?xed in the axial direction relative
formance of the transmission according to FIG. 7.
to each other, and also with two belt-sheave portions
As shown in FIG. 1, the drum 1 of a washing machine
which are displaceable axially in the same sense so that
is driven from a pole-switchable squirrel-cage motor
the displacement increases the effective sheave diameter 25 capable of selectively operating at two speeds depend
for one of the two belts and simultaneously reduces the
ing upon which group of poles is energized at a time.
eifective sheave diameter for the other belt. In a trans
Such motors are commercially available as standard prod
mission of this type, the axial pressure upon the V-belts
in the two transmission stages would be approximately
ucts. They may have two and four poles, for example,
to operate at a speed ratio of 2: 1. Driving power is trans
equal, disregarding the differences in the groove angle 30 mitted from the shaft 11 of the motor 2 to the shaft
which in any event remain within very narrow limits.
19 of the drum by a variable-ratio mechanism consisting
However, since the torques in such a plural-stage trans
of a V-belt drive which comprises a two-part belt sheave
mission and hence the pulling forces transmitted by the
3 on the drum shaft ‘19, a two-part belt sheave 4 on
respective belts, differ greatly from each other in accord
the motor shaft 111, and an endless V-belt 8. The motor
ance with the step-down or step-up ratio, the faster run 35 2 is energized from power-supply terminals 20 under
ning belt would be subjected to a considerably higher
control by a programming control device 7 illustrated
pressure force than the other belt because the force of
as a drum-type contactor in planar developed form,
the counter spring must adapt itself to the slowly running
which is provided with contact segments 5 and fixed
stage where higher torques are effective. In the fast
contacts 6. The control device 7 is essentially an elec
running stage, the high pressure in conjunction with the 40 trically driven timer as customary for automatic wash
high belt speed may result in excessive heating and great
ing machines. When the control device 7 is in Low posi
wear of the belt.
tion, one group of poles in motor 2 is active for oper
According to a more speci?c feature of my invention,
ation of low speed and the drum 1 is driven for washing
however, these difficulties are obviated as follows. A
operation. When the device 7 advances to High posi-'
compensating spring is mounted on the intermediate 45 tion, the other group of poles in motor 2 is energized
shaft between an axially ?xed belt portion and the axially
for driving the drum 1 at higher speed. As explained,
movable belt portions, and the force of the compensating
the transmission 3, ‘4, 8 now becomes effective to change
spring is directed against the action of the counter spring
its transmission ratio so as to gradually increase the drum
mounted on the drum shaft, thus reducing the axial stress
speed above the value that it would assume if the drum
imposed upon the belt in the fast running transmission 50 were simply driven at the speed of motor 2. Such in
stage. With the counter spring on the drum shaft and
crease continues until the drum 1 has reached the desired
the compensating spring on the intermediate shaft thus
high
spin-drying speed. Details of the variable-ratio
acting in opposition to each other, the centrifugal regu
transmission
and its operation will be described in a later
lating device correlated to the motor shaft need overcome
place.
only the difference of the two spring forces. This is favor
The embodiment schematically illustrated in FIG. 2
able to the performance of the transmission mechanism
is
to some extent similar to that of FIG. 1, identical
because this difference is relatively small if the centrifu
components being denoted by the same reference nu
gal weights, when in starting position, are located in the
merals respectively. According to FIG. 2, a single-speed
vicinity of the motor-shaft axis where the centrifugal
force is initially slight because of the small radius. Dur 60 two-pole drive motor 22 is used. It drives a two-staged
mechanical gear transmission 24 which in turn drives
ing the regulating operation the radius increases, the
the input sheave 4 of the above-mentioned variable
centrifugal force also increases, and the difference be
ratio transmission. The two speed steps of gear trans
tween the two spring forces to be overcome by the cen
mission
24 are electromagnetically controlled by respec
trifugal force also increases. Consequently, an adaptation
of centrifugal force and spring forces is readily possible. 65 tive control windings 26 and 28 so that only the one
gear step is active whose appertaining control winding
The above-mentioned and other objects, advantages and
is energized at a time. The program control device 27,
features of my invention, said features being set forth
when turning from Stop to Low position, energizes'by
with particularity in the claims annexed hereto, will be
apparent from, and will be described in, the following
means of its contact segments 25, the motor 22 and simul
with reference to the embodiments of drum-type washing 70 taneously the control winding 26 so that the drum 1 is
machines according to my invention illustrated by way of
driven for washing operation at slow speed. When there
example on the accompanying drawings in which:
after the control device 27 switches .to High position,
FIG. 1 shows schematically the components of a drum
‘the motor 22 remains energized but now the control
type washing machine essential to the invention includ
winding 28 is energized so that the input sheave 4 of
ing the laundry-receiving drum, the variable-ratio trans 75 the variable-ratio transmission operates at higher speed
3,088,303
5
and the variable-ratio transmission commences to increase
the drum speed up to the spinning value.
As will be more fully apparent from FIGS. 5a and
5b, each belt sheave 3 and 4 in FIGS. 1 and 2 comprises
a half-portion ?xed to the shaft on which the sheave is
mounted, whereas the other half portion is axially dis
placeable so that the V-groove of the sheave can be
come wider or narrower.
This should be kept in mind
with reference to the lateral view illustrated in FIG. 3,
showing the two extreme positions of the endless belt
8. Shown by a full line is the operating condition of
the belt for the low drum speed. Shown by a broken
line is the operating condition for the high drum speed.
FIG. 4 illustrates a modi?ed embodiment in which the
belt sheave 3’ on the shaft 19 or drum 1 has a ?xed
effective diameter (i.e. does not consist of two portions
of which one is axially displaceable relative to the other)
and only the belt sheave 4 on the motor shaft 11 can
vary its effective diameter for changing the transmission
ratio. In this case, a tensioning roller 9 is provided for
compensating the different belt lengths during changes
6
to the invention. The abscissa denotes time (t), and the
ordinate indicates the rotating speed (n) of the drum in
revolutions per minute. Upon to the moment t1, the ma
chine runs in washing operation. At this moment, the
two-stage drive is switched from Low to High by the
program control device vof the machine (7 in FIG. 1, 27
in FIG. 2).
Now the drum speed n increases up to the
moment t2 in which the centrigual regulator (15) be
comes act-ive. The moment t2 is reached when balance
obtains between the centrifugal force of the regulator and
the force of the counter spring.
These two forces must
be given such an approximate dimensioning that 12 would
be attained at about a drum speed of 60 to 70% of the
speed effective if only the high switching stage of the
gear transmission 24 (FIG. 2) or of the pole-switchable
motor 2 (FIG. 1) were permitted to operate and the
variable-ratio transmission were kept at a ?xed ratio. At
the just-mentioned speed the maximum power of the
motor is substantially reached. Beginning with the
moment t2, the regulator 15 causes the speed of drum 1
to be increased by the continuously regulatable transmis—
in transmission ratio. The roller 9 is pressed against
the belt 3 in the direction of the arrow, for example by
means of a spring, and may be journalled, for example,
sion up to the maximum value which is reached at the
moment t3. That is, from moment 12 to moment t3 the
sioning roller 9 is in the full-line position at the left,
A two-stage variable-ratio transmission embodying the
drum speed is being increased from the low washing speed
on an arm (not shown) pivotally mounted on the motor 25 up to the spinning speed, and the spin-drying operation
proper commences with the moment Is.
shaft 11. During operation at low drum speed, the ten
above-mentioned features of the invention will be de
scribed presently with reference to FIG. 7 and with ref
drum speed, the roller 9 occupies the broken-line posi 30 erence to the diagram of FIG. 8 indicating the forces
and the V-belt 8 ms with the smallest diameter of the
driving sheave 4 on the motor shaft 11. At the highest
tion, and the driving sheave i4 is active with its largest
diameter.
As more fully shown in FIGS. 5a and 5b, the driving
belt sheave 4 in a machine according to FIGS. 1 or 2
acting upon the counter spring and compensating spring
in vdependence upon the amount 1,“ displacement.
The transmission mechanism "shown in FIG. 7 is ap
plicable in lieu of the single-stage variable-ratio trans
comprises a disc 12 rigidly joined with the shaft 11 of 35 mission of the embodiments described above, in conjunc
tion with an electric drive motor and a control device as
the electric motor 2, and a disc 13 axially displaceable
on the shaft 11. A helical pressure spring v14 tends to
force the disc 13 away from disc 12 to the limit posi
tion shown in the upper portion of FIG. 5b. In this
position, the driving belt is in its innermost operating
position 8a so that a relatively small driving-sheave di
ameter is effective. This position corresponds to the
washing operation of the drum. When passing to the
spin-drying operation, initiated by switching of the motor
2 (FIG. 1) to high speed, the revolving speed of the 45
motor shaft 11 increases. When it reaches a given value,
a centrifugal weight ‘15, pivotally connected at 16 with
the driving disc 12 by a sleeve 17, is lifted and then
forces a pressure dog 18 against the displaceable disc
13. As a result, the disc 13 is gradually forced toward
the disc ‘12 in opposition to the force of spring 14 to
the limit position shown in the lower portion of FIG. 5b.
In the latter position, the driving belt is in the position
8b in which the largest diameter of the driving sheave
is effective.
The driven sheave 3 (FIG. 5a) comprises a disc 20
rigidly joined with the shaft 19 of the washer drum 1,
and a disc 21 am'ally displaceable relative to disc 20.
A helical compression spring 22 forces the disc 21 to
ward the disc 20, so that the disc 21 assumes the broken
line position during washing operation and the driving
belt occupies the position 8a corresponding to the largest
shown in FIG. 1, or in conjunction with a motor, two
step gear transmission and control device as shown in
FIG. 2. It may be assumed, for example, that the input
sheave of the variable-ratio mechanism according to FIG.
7 is driven from a pole-switchable motor with two and
four selectively operable poles. Denoted by 31 in FIG. 7
is the shaft of the washer drum, by 32 the shaft of the
motor, and by 33 the above-mentioned intermediate shaft.
The driving sheave on the motor shaft 32 comprises an
axially ?xed portion 34 and an axially displaceable por
tion 35 which jointly cooperate with a V—belt 36.
Mounted on the motor shaft and axially rigid relative
thereto is a guiding body 37 for centrifugal Weights 38.
When the motor shaft rotates at a speed above a given
value, the weights 38 move outwardly in the directions
indicated by arrows 39 and press the axially displaceable
portion of the belt sheave toward the left in the direction
of the arrow 40 thus providing for the increased driving
speed of the drum required for spin-drying operation.
The intermediate shaft 33 carries two axially ?xed ‘belt
sheave discs 41 and 42 between which an am'ally dis
placeable middle structure is mounted which forms two
sheave portions 43 and 44. The belt sheave 36 engages
the sheave portions 42 and 44. Another belt 45 engages
the sheave portions 41 and 43 and serves for driving
the belt sheave on the drum shaft 31.
.
effective diameter of the driven sheave 3. During spin
The drum shaft 31 carries an axially ?xed sheave disc
ning-drying operation, the belt is forced downward to 65
46 and an axially displaceable disc 47, both cooperating
‘the position 8b so that the disc 21 occupies the full
with the V-belt 45. A helical counter spring 48 mounted
line position in which a smaller diameter of the driven
on the drum shaft 31 tends to force the displaceable disc
sheave 3 is effective. This is due to the action of the
47 toward the ?xed disc 46. A helical compensating
centrifugal Weight ‘15. If desired, however, the upper
sheave 3 may also be provided with a centrifugal device 70 spring 49 is mounted on the intermediate shaft 33 between
the axially ?xed portion 42 and the axially displaceable
corresponding to that shown in FIG. Sb and set to oper
middle structure 43, 44. Spring ‘49 acts in opposition to
ate simultaneously with, and in the same manner as, the
the force of the counter spring 48.
device described above with reference to FIG. 5b.
In FIG. 7, the belt position corresponding to the wash_
The coordinate diagram of FIG. 6 is typical of the
performance obtained with a washing machine according 75 ing operation is shown by full lines, whereas the belt posi
3,088,303
tion corresponding to the spin-drying operation is indi
cated by broken lines.
In the graph shown in FIG. 8, the horizontal reference
line indicates the direction of displacement caused by
the centrifugal motion of the Weights 38, this motion
being in the direction of the arrow 40 and causing a com
pression of the counter spring 48 and of the compensat
ing spring 49. The amount of displacement thus centrif
8
4. A washing machine according to claim 1, including a
counter spring in engagement with said displaceable disc
of said ?rst one of said sheaves for ‘biasing it away from
said ?xed disc of said one sheave, and said weight means
having a pivot axis in ?xed relation to said axially ?xed
disc of said one sheave and being centrifugally movable
outwardly about said axis for displacing said displaceable
disc of said one sheave in opposition to force transmitted
by said belt from said spring.
displacement line are the spring forces of the counter 10
5. In a drum-type washing machine having a laundry
ugally effected extends from al to 02.
Plotted on the
spring 48 (G1, G2) and the spring forces of the com
pensating spring 49 (A1, A2), so that the force difference
receiving rotatable drum, drive means for said drum, and
a control device connected with said drive means for
F1 or F2 to be overcome 'by the centrifugal force of the
sequentially switching it to operate at low speed for wash
weights 38 is apparent. The increase of the difference
ing operation and high speed for spin-drying operation,
valve from F2 to F1 can be dimensioned by correspond 15 the combination of a transmission mechanism disposed
ing choice of the springs 48 and 49 so that it corresponds
between said drive means and said drum and having a
to the increase in centrifugal force acting upon the weight
transmission ratio continuously variable between a lower
38 during automatic regulating operation.
and an upper limit, said mechanism having control means
When employing such a two-stage belt mechanism, the
responsive to operation of said control device for causing
increase in force of the counter spring on the drum axis
said ratio to continuously vary in the drum-speed in
can be kept very small, in some cases even ‘negative,
creasing sense up to the spin-dry speed when said drive
corresponding to the torques to be transmitted on the
means is switched from washing to spin-drying operation,
drum shaft. With the corresponding increase in force of
said transmission mechanism comprising a two-stage V
the compensating spring on the intermediate shaft, the
belt transmission having a ?rst sheave coaxially joined
increase in the di?erence between the two spring forces
with said drive means, a second sheave coaxially joined
can ‘be so dimensioned that it corresponds to the increase
with said drum, an intermediate shaft parallel to the axis
of the centrifugal force acting upon the centrifugal regula
of said two sheaves, a twin sheave on said shaft, and two
tor so that a favorable regulating characteristic is ob
tained.
endless belts drivingly connecting said ?rst sheave with
said twin sheave and connecting said twin sheave with said
second sheave respectively; each of said ?rst and second
Upon study of this disclosure, it will be obvious to
those skilled in the art that my invention is amendable
to a variety of modi?cations and hence can be given em
sheaves having two component discs of which one is
axially ?xed and the other is axially displaceable, said two
ibodiments other than particularly illustrated and de
discs forming together a belt-engaging groove whose ef
scribed herein, without departing from the essential fea
fective diameter varies with the displacement of said
tures of the invention and within the scope of the claims 35 other disc; a centrifugal weight device joined with said
annexed hereto.
?rst sheave and engaging the displaceable disc of said
1 claim:
?rst sheave for displaceing it in dependence upon the
1. In a drum-type washing machine having a laundry
speed of said drive means; a counter spring engaging said
receiving rotatable drum, drive means for said drum, and
displaceable disc of said second sheave and having a force
a program control device connected with said drive means
direction opposed to the action of said centrifugal weight
for sequentially switching it to operate at a lower speed
device; said twin sheave comprising two axially ?xed discs
range for Washing operation and at higher speed range
and two intermediate disc members jointly displaceable
for centrifuging operation, said drive means including a
axially in the same sense so as to form together with said
motor and a two-step gear transmission mechanism dis;
two latter ?xed discs two ‘belt-engaged grooves which in
posed between said motor and said drum and shiftable 45 versely vary their respective diameters with axial displace
between a ?rst and second speed for transmitting power
ment of said disc members; and a compensating spring
to said drum and increasing the speed thereof, a con
mounted on said intermediate shaft and in biasing en
tinuously variable V-belt transmissionv having a pair of
gagement with said disc member in a ‘force direction op
sheaves each having a displaceable disc and connected
posed to the effect of said counter spring, whereby said
between said two-step transmission mechanism and said 50 compensating spring reduces the axial stress imposed upon
drum for controlling acceleration of said drum within said
the belt running at greater speed than the other.
higher speed range, and a centrifugal weight device joined
6. In a washing machine according to claim 5, said
with a ?rst one of said sheaves and engaging the displace
counter spring and said compensating spring having re
able disc of said ?rst sheave for displacing the latter in
spective spring characteristics adapted to each other so
dependence upon the second speed of said two step trans 55 that the difference of their respective forces increases
mission, said control device having means =for sending a
substantially in accordance with the increase in centrifugal
signal pulse to shift said transmission from a said ?rst
speed to said second speed, said centrifugal device being
responsive to the two-step transmission reaching said sec
ond speed.
2. In a washing machine according to claim 1, said
motor having a single operating speed.
3. In a washing machine according to claim 1, said
V-belt transmission having a variable transmission ratio,
said ?rst sheave being of variable effective diameter and
coaxial-1y joined with said drive means; a counter spring
engaging said ?rst sheave and biasing it in the direction
required to reduce said transmission ratio, said centrifugal
weight device being movable outwardly by centrifugal
force of said centrifugal device during the ratio-changing
operation of the transmission mechanism.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,253,634
2,311,924
2,496,061
2,651,210
2,881,633
2,942,447
Clark ______________ __ Sept. 8, 1953
Warhus _._;_ _________ __ Apr. 14, 1959
Rickel et al. _________ __ June 28, 1960
143,605
Australia ____________ __ Sept. 27, 1951
force and operatively connected with said ?rst sheave for 70
varying said diameter in opposition to said spring to in
crease said transmission ratio.
Mack _______________ __ Aug. 26, 1941
Bassett _____________ __ Feb. 23, 1943
Miner _______________ __ Ian. 31, 1950
FOREIGN PATENTS
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