Note: Descriptions are shown in the official language in which they were submitted.
`~ 5~8
This invention relates to methods of and~or apparatus
for actuatin~ clothes washing machines and/or clothes washing
machines including such means and has been devised for use
in clothes washing machines of the agitator type, that is to
say the type in which a rotatable spinning bowl is provided
in a container and in which bowl is mounted an agi~ator, the
agitator being in use, in an agitating phase, rotated over
a range of rotatory ~novement first in one direction and then
in the opposite direction, and in a spin phase said bowl is
continuously rotated in one direction for a period o~ time.
It is an object of the present invention to provide
methods of and/or apparatus for actuating clothes washing
machines and/or clothes washing machines including such
actuating apparatus which will at least provide the public
with a useful choice.
Accordingly in one aspect the invention consists in a
method of actuating a clothes washing machine of the type
described, said method including the steps of, in the
agitating phase using an electric motor connected to said
agitator through a speed reducing transmission to rotate
first in one direction and then in the other so that said
agitator in turn is rotated over angular rotations in each
direction and in said spin phase causing said motor to be
connected to said bowl and to rotate the latter continuously
in one direction at a higher speed.
In a further aspect the invention consists in apparatus
for actuating a clothes washing machine, said means comprising
an agitator shaft, an agitator mounted on said shaft, a
hollow spin shaft coaxial with said agitator shaft, a
- 2 -
3 ~
s~-)innin~ hnw] mourltc~l nn sai(l sJ)in sh.lrt and in wllich sai(l
a~itator is mounted, an electric motor havin~ cl drive shalt,
a speed reducing transmission means connecting said drive
shaft to said agitator shaft so that rotation of said driving
shaft in one direction or the other causes rotation of said
agitator shaft in the saMe sense as the driving shaft, a
lost motion device between said agitator shaft and said spin
shaft permitting said agitator sha-ft to rotate in either
direction without causing material rotation of said spin
shaft and electric supply and control means supplying said
motor with current so that in an agitating phase, said motor
is rotated cyclically first in one direction then in the
other to cause said agitator to oscillate without causing
said bowl to be moved materially from a stationary position,
and in a spin phase causing said motor to rotate continuously
so that free play in said last rotation device is taken up
and said bowl caused to spin at spinning speed, said electric
supply and control means controlling the energy supplied to
said motor so that the spinning speed is at least ten times
the maximum agitating speed of said motor.
In a still fuIther aspect the invention consists in a
clothes washing machine which includes apparatus for actuating
the same when constructed and arranged according to the
preceding paragraphs.
To ~hose skilled in the art to which this invention
relates~ many changes in construction and widely differing
embodimerlts and applications of the invention will suggest
themselves without departing from the scope of the invfntion
as defined in the appended claims. The disclosures and the
vt9e~
de~criptions hcreirl .~rc~ rclv i'l'lllstr;Jtivc.~ is IIOt
our intention to lirnit the scope of the inverltion hy those
disclosures and descriptions, or otherwise, than by the
terms of the appended claims.
S One preferred form of the invention will now be described
with reference to the accompanying drawings in which:
Figure 1 is a vertical partly diagrammatic sectional
elevation of a clothes washing machine of the type described
incorporating the invention;
Figure lA is a scrap vi.ew of an alternative lost motion
devi.ce;
Figure 2 is a scrap plan view on the line II-II, figure
l, and
Figure 3 is an electrical diagram o:E electric supply to
and control of a motor forming part of the clothes washing
machine of figure 1.
Referring to the drawings, a clothes washing machine 1
of the vertical axis top loading type is shown diagrammatically
and is provided with an outer container (not shown) and an
inner clothes bas'ket or spinning bowl 2 which is perforated
in the known way. This bowl is mounted OJI a spin shaft 3
running on bearings 4 and 5 so as to be freely rotatable.
An independently rotatable agitator 7 is mounted on a spindle
8 coax;ally with the member 3. The spindle 8 is dr;.ven
through a collet 9 mountecl in a conical.ly apertured member
10 driven by a bolt 11, by pulley 12, a belt 13, and a
urther pulley 14 mounted on the shaft 15 of an electric
motor 16. The speed reduction is in the range 8:1 to .20:1
preferably 14:1 or to suit the motor characteristics. l'he
- 4
q. :~L 8 ~ e) ~
electric motor is For cxam~)le a IhoTrlson l~r(lndt motclr type
19/70/45 which is a permanent ma~ne~ ~C motor which wil]
operate over a wide ran~e of speeds for example between
close to zerv and 17000 revolutions per minute.
A lost motion coupling means is provided between the
pulley 12 and the spin shaft 3 and thus the bowl 2 comprising
for example a pin 20 arranged parallel to, but displaced a
distance from the longitudinal axis of the spindle 8. The
pin 20 preferably car~ies a resiliently flexible e.g. rubber
bu-ffeT 21 on it~
An arm 22 is fixed e.g. by a U bolt 23 to the shaft 3
with the radius of the arm 22 greater than the distance of
arm 22 from the centre of the shaft 3. This arrangement is
such that in an agitating mode the pin 20 can rotate close
to 2~ radians without moving the arm 22 but in a sp;n mode,
the buffer 21 on pin 20 "engages" the arm 22 and carries
~ha-t arm and consequently the spinning bowl around with the
shaft 8 when the motor 15 is rotated continuously as will be
described further shortly.
If it is required to agitate the agitator over a greater
range of movement then 271 radians, the arrangement of
-figure lA can be used in which pin 21 engages an intermediate
arm 60 and arm 22 CaTrieS a EurtheT pin 61. The arm 60 is
free on the hollvw shaft and thus up to 4~ radians of movement
of pin 20 can result without material movement of arm 22.
This lost motion arrangement can be repeated as desired.
The agitator 7, bowl 2 and associated container are
resiliently mounted in any convenient way e.g as descTibed
in our New Zealand patent specif;cation No. 194730, in a
I~t)~
cahinet such a~ th;lt shown in our copcrlding N~w Zc.llan~]
patent s~ecification No 189708 and to assist in counter-
balancing out of balance clothes during spinning, an annular
tube 24 is provided partially filled with a liquid and
having transverse baffles (not shown~ to limit transfer of
the liquid. Additionally a plurality preferably two balance
weights 59 are pivotally mounted on the spin shaft 8 and
these weights in use take up positions to reduce imbalance.
As is well known the bowl is rotatable at high speed,
usually over 1000 RPM ~or extracting -fluid from the clothes
(i.e. spin drying) and the agitator cyclically reversible
for clothes washing. Since it is desirable that the rotation
of the bowl be braked if the lid is opened, ;f mains power
is switched off or lost in fault conditions 7 the present
invention in the preferred form provides means of converting
the kinetic energy of moving parts into electrical energy
and absorbing that energy pre-ferably by use of a resistor
i.e. electrical braking characterlsed in that means are
provided to control the braking current at specific RPM
~o designated ~alues which may be functions of RPM. The
agitator in use rotates to and fro pre-ferably through ]ess
than 27r radians through a greater range of motion is possible
to cause washing of the clothes and bowl rotation can be
caused to occur by providing free agitator rotation between
defined limits but such that continued rotation of the
agitator in one direction or the other will cause rotation
of the bowl in the same direction by engagement of bu-ffer 21
with the arm 22.
- 6 -
l`o ~ive theL;e actions a prcrerr(?d ~lcctrica:l sur)ply and
motor control circuit will be de.scri.~ecl which will give ~hc
preferred functions that must be perforrned which are firstl~
control of mOtOT speed a~ one of several selected levels
which are subs~antially independent of motor load within a
defined range of loads, secondly control of orderly acceleration
deceleration and Teversing of the motor, thirdly control of
braking from a spin or other speed with or without the
presence of main supply voltage and initiated either by
external means such as opening of the spin. drum lid or
internally such as by loss of mains power, and fourthly
control of orderly transfer from one demanded mode of operation,
for example agitationt to another for example spin, as
requested either by for example a mechanical appliance timer
circuit or control microprocessor, and as required for
co-rrect functioning of the overall electro-mechanical drive
package.
A circuit to perform these functions will now be
described.
With reference,to -figure 3 the motor 15, which is to be
controlled, is as stated, a direct current reversible motor
of a type whi.ch can have its speed controlled by controlling
the average ~C voltage applied across the motor and which
can be reversed by reversing the polarity of the voltage
across the motor) for example a permanent ma~net commutator
DC motor. The circuit is supplied from e.g. 240v 50 cycle
AC supply at P ~ N and through a full wave rec~ifier circuit
26 and a reservoir capacitor 25 is connected across the DC
leads rails A and O~ from this rectifier DC voltage supplied
to r.lils A and ~) the latter hein~ tlle OV sur~lv c~rnlrlon ra;1.
A low voltage power suppl~ 2~) i.s provide(] ancl lS irl part an
AC to DC converter and in part a DC to DC converter. The
motor 15 is arranged in the centre of a reversing bridge and
current path selection circuit comprising for example a
network of switching devices for example changeover relays
having magnetically actuated movable contacts and fixed
contacts 30, 31, 32 and 33 and diodes 34, 35, 36 and 37.
Thus the motor can be driven in one direction by current
flowing along the pathway from rail A, diode 34, contact 30
motor 15, contac~ 33, diode 37, power modulating switch 38
and a current sense resistor 39 to common supply OV. The
motor can be driven in the opposite direction by current
-flow t.hrough diode 35, contact 32, motor 159 contact 31,
diode 367 switch 38 and resistor 39.
Switch 38 is a power modulating switch which may, for
example, be a power bi-polar or power field effect transistor,
a gate turn off thyristor or other similar device. The
switch 38 is used to modulate the application of supply
voltage to the motor 15 thus for example if switch 38 is on
for 50% of the time the motor 15 experiences a drive voltage
equivalent to approximately 50% of the supply voltage. l-f
the switch 38 is on for say 5% of the time then the motor 15
experiences a drive voltage equivalent to approximately 5%
of the drive voltage. ~he total switching period may be of
the order or example about 100 microseconds.
Other devices used in the circuit are introduced into
the following description of the operation of the circuit
and a typical switching cycle in simplified form is as
follows:
-- 8
C~
For examr)le cont.lct~ ~() an(l :~ aT~ m,~ il nOt alro~
in that confi~uration, a short p~riod prior to switch 3~
being turned on. When switch 38 has been turned on, current
builds up in thc motor circuit loop through diode 34, oontact
S 30, motOT 15, contact 33, diode 37, switch 38 and resistor
39. The drive current is principally determined by firstly
the current flowing in the circuit loop of diode 34, contact
30, motor 15, contact 32, diodes 37 and 44 at the moment of
turn on, secondly the values of inductance and resistance
associated with motor 15, and thirdly the motor back EMP and
finally the supply voltage of circuit rail A relative to 0V
rail D.
A controller circuit 40 is provided connected to relay
coils and drive circuit 29 to control operation of the
contacts 30 to 33 and also via a demanded speed selection
circuit 41 and a switching regulator 42 to control switch
38.
Motor current is sampled by the motor current limit
circuit 43 across a current sensing component, preferably
current resistor 39. Motor current information is -fed to
switching regulator 42, e.g. an (SR) IC, and this may be
used to terminate the on-time of switch 38 should excessive
current flow be sensed in the -resistor 39. This may be
achieved in the manner common to switching motor speed or
voltage regulator circuits. Thus the maximum current that
can flow through resistor 39 is limited. If the current is
not excessive termination of the "on" period is controlled
by the switching regulator 42 in conjunction with controller
40 at a percentage cycle on time appropriate to achieve the
.3 1.~ 5 ~
de~ire~l ro~ational specd or thc nlo~or :l5. At tu-rrl of r, tilC
inductance associated wi~h the motor 15 attemptC; to keer,
current flowing and would cause the volta~es a~ the circuit
rail B to rise to potentially damaging levels if preventive
S measures were not taken. Accordingly, diode 44 is provided
to allow motor current to continue to flow in the loop
compTising diode 34, contact 30, motor 15, con~act 33 and
diodes 37 and 44. The principal purpose of capacîtor 45
and resistor 46 is to control the safe operationg area loci
for example as is normal in the switching of inductive loads
with bi-polar transistors.
Thus the e~fective motor drive voltage is controlled
through the peTcentage on to off ti.mes of switch 38 as
switched by switching regulator 42 which is in paTt a feed-
back control circuit, error ampli-fier and modulator9 for
example as used in the switch control of motor speed. Such
a circuit requires input information in the form of demand
and actual speed and this is delivered in current analogue
form to the error ampli:fieT summing po~nt C.
The information on motor speed is derived indirectly in
order to minimise the costs of coJnponents and by means which
require no tachometers or velocity pulse gerlerators. By
approximating the motor as an equivalent circuit having
series resistance R and back F,MF F, the speed can be approximated
as being proporti.onal to E which is the effective motor
terrninal voltage V less the I x R drop where I is motor
current. Thus the speed is proportional to V~IR.
The term for I is obtai.ned by using a circuit ~7 which
is essentially a peak-hold circuit which looks at the pulse
- 10 -
15B~
that appe.lrs across resistor 39 dllrin~ the "on" timc of
switcil 38 and is arran~ed to traTIsform this to a continuous
scale current representative of IR whic}l is delive-red to the
sulnming point C
The term for V is derived by measuring the volta~e
across the motor, which is, to sufficient accuracy, the
voltage at circuit rail B with Tespect to the supply voltage
at rail A. Use is made of the fact that the voltage at rail
B is a switched waveform rather than a steady DC voltage,in
order to translate this waveform to a stream of current
pulses. The length of these pulses is dependent upon the
on-time of switch 38 and the magnikude of these pulses is
dependent upon the instantaneous value of the supply voltage
at rail A. This pulse train is fed ~o summation point C and
integrated to give an analogue of motor voltage.
The circuit can be built for either polarity of supply
with appropriate changes to the polarized components for
example the diodes transistors and the like but for the
purpose of this description the supply will be considered as
poi.tive to OV supply common rail D. The description of
CiTCUit operation will also assume a zero voltage drop
across diodes in the forward direction.
The demanded speed selection circuit 41 is provided
from known art for selecting desired motor speed which is
transformed and delivered to the summing point C from circuit
41 as the current analogue of desired speed. It will be
apparent how the current analogues of desired speed, motor
terminal-voltage, and motor current, when delivered to the
summing point C are used to derive drive pulses on lines E
~,~,sn~ 3
and F and a~so(:i~at(~ dr:ivc circuit to control switch 3P, an(l
thus provide closed loop feed-bclck control oI mo~or speed.
Controller 40 and switching regulator 42 provi.de other
functions as follows:
(a) Termination or suppression of drive pulses in over
current conditions.
(b) Control and sequencing of relay switchlng contacts 30
to 33 and swi.tch 38 as required -for agitation, spin and
braking operations.
(c) Control sequenci.ng of relays swi*ching contacts 30, 33
and 38 as required for braking operations.
Describi.ng these functions and for the transitions between
these operations in turn:-
(a) Motor current limit circuit 43~ which can be based on
known circuits, derives motor current information from
the voltage pulses across resistor 39, provides selectable
- scaling and optionally low pass filtering and passes
this information to switching regulator 42 at the
correct time for it to terminate or suppress drive
pulses as is common with switching regulator circuits.
Selection of scaling may be by any means suitable to
the application.
~b~ Diodes 34 to 37 and the control and sequencing of relay
contacts 30 to 33 and switch 38 select motor direction
or braking modes of operation and havè due regard for
need for proper switching of inductive currents and
avoidance of short circuits.
(c) The next section describes the braking function.
- 12 -
x~ (~ t~
'I`he hrakin~ metllltl consists Or pclrts ol~ ttle circu~
described so far with the additlon of a relatively lo~
resistance current pathway includin~ ~iode 50 and a relatively
high resistance current pathway including resistor 51.
Braking from a speed controlled mode operates as -follows:
Motor stopped detection circuit 52 is in the current
path which is common to the relatively low resis~ance braking
path including diode 50 and the relatively high resistance
braking path including resistor 51 and deteector circuit 52
~ therefore conducts braking current at all times during the
braking mode of operation. A signal is fed from circuit 52
to controller 40 upon completion of braking and controller
40 is then allowed to set up the reversing bridge and current
path selection circuit for any other mode of opera-tion e.g.
agitate.
In braking mode contacts 31 and 33 are closed. Switch
38 is turned on and current builds up at a rate determined
by the back EMF of motor 15 and the circuit inductances and
resistances around the loop consisting of contact 31, diode
36, switch 38, resistor 39, diode 50, circuits 52, contact
33 and motor 15. In the braking mode the switch 38 is
switched at frequencies similar to those used in the speed
control mode. The pulses are derived from the switching
regulator circuit 42 which controls speed but the mod-llator
is set for maximum on time by controller 40 in conjunction
with demanded speed selection circuit 41. As soon as sufficient
braking current is flowing pulse termination or suppress~on
using the same circuits as in the speed controlled mode is
used to control steady flow of braking current at a level
- 13 -
i~3~)tj~
~e]ected throu~}l rnotor currcnt Iimit circuit 4:', as controlle(l
bv controller 4~
When turn off o-f switch 3~ occurs the current -flowing
changes its path. Snubber/filter components 45 and 46
modify the waveforms if necessary to ensure safe and satisfactory
operation of the circuit. After turn-off, current flows in
a loop comprising motor 15, contact 31, diode 36, resistor
51, circui~ 52 and contact 33. ~uring turn on, the back EMF
oE the motor 15 is used to store energy in the inductance in
motor 15. A~ turn off, the rate of change o-f current in the
inductance generates voltage to force the current around the
new path and so dissipates energy principally in resistor
51. Resistor 51 may be sized so that the voltage developed
across resistor 51 by current flow therein is a convenient
level, perhaps a little below normal supply voltage. As
switch 38 is controlled to turn off at a defined current
level and this current is divertable through resistor 51
which is of a defined value, then it is possible during the
turn off period to develop a constant voltage across a
single fixed energy dissipating resistor independent o:E the
back. EMF of the motor providing only -that the back EMF is
sufficient to develop the necessary limiting level of current
in the relatively low braking cu-rrent path i.ncluding diode
50 during turn on.
It is thus possible to achieve controlled current
braking of the motor independently of motor speed iE dèsired
typically down to 5% or 10% of full speed, and with the use
of a single fixed value braking resistor. The control;led
current may be controlled as a function of speed or time by
- 14 -
circllit 4:~ and u~on com~ rld fronl corltrollcr ~ IJsin~, knOWTI
means or simply held at ~ constant vallle.
lt is desirablc that a safety braking function operates
whether mains supply voltage is present or no-t and braking
performance can be achieved with no mains supply unti,l the
motor ceases to rotate or at least rotates only slowly,
perhaps 10% of ull speed.
This is achieved by feeding current from the high
voltage source developed at point B during braking through
diode 44 to reservoir capacitor 25 and so to power supply 26
which is i.n part a DC ~o DC converter and provides low
voltage power to the control circuits and because the back
EMF is used to generate the aorementioned high voltage
during braking, the power supply 26 does not experience any
significant drop in input voltage until the motor is almost
stationary, even in the absence of mains supply.
By maintaining the low voltage for the control circuits
and because braking current relies on the presence of the
back EMF only and not the supply voltage, braking is controlled
down to low speed even in the absence of mains supply.
Normal drive power for the motor ;s provided by direct
rectification of the AC main.s supply by diode bri.dge 26.
Capacitor 25 provides smoothi.ng and resîstor 27 contro].
in.rush currents. Capacitor 25 and resistor 27 may be sized
to control the harmonic cllrrents flowing in the mains supply
li.nes. For more general use other supply means such as
batteries may be used.
With a battery supply or other supply capable of s-toring
full braking energy, resistor 51 may be omitted and regenerative
- 15 -
~ 3
brakin~ ~chieve~ ecalJse brakin~ cnergv i.s rctl~rnc(l to -the
battery via diode 4~ in thc sul)pl) ~3y thc ad(litior) Or
extra cornponents to mirror the existing relatively high
resistance braking circuit including resistor 51 and connected
symmetrically on the other side of the motor, braking may be
performed from either direction of rotationO Regenerative
and bi-directional braking are features that make the circuit
suitable for vehicle use or as a general purpose drive
controller.
The equipment will run the motor at reversal rates down
to any required lower limit and the spinning speeds are
limited only by mechanical requirements and motor characteristics.
However in practical parameters for example with an agitator
and spin bowl of a washing machine, cyclic reversal of the
relays 29 allows reversal of direction of the motor at for
example a relatively low speed e.g. 14 RPM maximum of -the
motor to obtain an agitator action withirl the bowl and also
high speed rotation e.g. 17000 RPM of the motor beillg at
14:1 speed reduction betl~een motor pulley 14 and pulley 12,
a spin bowl speed of about 1200 RPM in one direction of the
agitator and bowl can be achieved for a spinning operat;on
to remove substant;al wa-ter or moisture from, for exaTnple 9
clothing within the bowl. Thus the ratio of motor speeds
between spin and agitate can be greater than 10:1 and are
preferably less than 15:1 in practical applications also.
Furthermore during, for exarnple, supply voltage fa;lure
or when the mains supply is switched off the back EMF of the
motor can be used to keep the control circuits powered up
until a relatively low level of bowl rotation has been
reached.
- lG -
~ 5~
Thus it is an advanta~e of a-t ]eas~ a p-rererrecl form Or
thc invention that a vertical axis washin~ machine can b~
designed and constructed with less moving parts and for a
potentially lower cost than has been possible up to this
point in time. Furthermore other advantages, features and
operational characteristics of the preferred form of the
invention are as follows:
l. The relay contact circuit used is a low cost means of
reversing a DC motor when combined with a semi-
conductor device as a power switch.
2. A standard switching regulator ~SR) IC is used as a
control element.
3. Current limit is achieved by the use of theSR IC dur;ng
the speed control phase.
4. Speed control is achieved by generating the necessary
MSR (mark space ratio) based on a-verage motor current,
motor resistance, average motor drivc voltage, and
known voltage constant.
5. Low voltage semi-conduc-tors are used as voltage feed-
ZO back.
6. If desired a sot start feature is optionally provided
for the control of mechanical shock using standaTd
features of the SR IC.
7. The use of motor back EMF and inductance is used to
generate a constant voltage for application across a
braking resistor instead of on]y speed proportional
back EMF. Use of only one braking resistor is an
advantage,
- 17 -
t) ~
8. 'I`he circllit uses h.lc~ ~MI: .In~l induct;ve kick Lo keeT)
the low vo:ltage ~ower supply alive tllrou~rh a switching
regulator so as to en.able braki.ng to be completed even
after the loss of mains power.
9. Use of the same SR IC and the same swit~hing transistor
is used for speed control to sample braking current
through the current measurement resistor and to regulate
braking current as required.
10. ~ero speed demand is used to allow relay contac-t current
to decay during di.rection or mode changing to prevent
contact arci.ng.
11. Control circuit referenced to negative output of the
bridge rectifier is used thus simp].ifyi.ng the drive
circuits for the switching transistor and current
sensing.
12. The circuit has the ability to use a fixed period
between agitate motions to allow the agitator to come
to rest so that the electrical energy is not wasted in
plugging the motor, and to make full use of the initially
stored energy, if desirable and dependent upon the
load.
13. Only one Iree wheel diode is used across the complete H
network.
14. The current limit may be different for agita~e and
braking spin modes and acce].erate to spin spced on spin
current limit.
15. Profiling of the hraking current to the maximum within
the current vs speed profile is used.
- 18 -
r) ~
16. The rnains voltage 5Wi tching enables ~he use of standard
timers, switches and contac~s.
17. Controller 24 may be used to vary the speed of the
motor within the period of an agitator stroke and so
the agitator speed-time profile can be tuned to a
desired shape in order to optimise washing efficiency.
18. Controller 24 may be used to provide the user ~ith
several selectable combinations of agitator speed
profiles and agitator reversing rates to provide a
useful range of washing actions to cope with various
conditions.
19. Controller 24 may be used to provide the user with
seve-ral selectable spin speeds and the value of these
speeds and the rates of acceleration up to these speeds
can be set during production to suit differing washing
machines and/or performance requirements.
- 19 -
