Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF TElE INVENTION:
The present invention relates to water fill control
systems for domestic washing appliances such as
household dishwashers~
In such devices it is known to provide an
electromagnetically operated water inlet valve for
controlling water fill to the washing tub from the
household water supply line. The inlet valve is
energized ~y a programmer timer to control the filling
of the washing tub. The water inlet valve commonly has
lO a flow control device, such as a deformable elastomeric
washer well known in the art, for providing a relatively
constant flow rate for an anticipated range of water
supply pressures. Known machines thus control water
volume ill by maintaining inlet valve open for
15 permitting flow at the controlled rate for a
predetermined time interval~
Where water fill is accomplished by timing a
controlled 10w rate, the flow control must be set at a
rate such that there is sufficient water fill to
20 accommodate the various soil conditions of the articles
and minimum filling interval taking into account timer
unction tolerances. In the prior art fill systems this
has resulted in excess water fill where only a minimal
50il condition is encountered.
A motor driven pump is usually provided to
recirculate the washing water through spray nozzles to
effect cleaning of the dishesO However/ it has been
found that substances such as egg white, milk, detergent
and certain rinse-aid additives can cause foaming and
30 cavitation in the recirculation pump thereby producing
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insufficient pressure in the washing spray nozzles.
Thus, if a timed controlled-rate fill is fixed to
provide a fill volume to a~commodate normal soil
conditions without the presence of foam producing
agents, in the event of their presence, insuficient
washing results. If, on the other hand, the timed
controlled-rate fill is fixed to provide a fill volume
sufficient to provide adequate wash pressure even in the
presence of foam producing agents, then in the absence
10 of such agents, excess water is present which results in
excess power consumption for heating the water and
washing pump operation.
In one type of known machine, the wash pressure pump
motor is reversed for the drain function; whereas in
15 another type of ~nown machine, the pump motor rotation
is unchanged and a programmer controlled drain valve is
actuated. In the reversible motor arrangement, drain
failure due to an open motor coil can result in multiple
filling upon subsequent programmer activation of fill
cycles~ ~n the drain valve arrangement, an open circuit
in the drain valve could also result in multiple filling
upon subsequent timer/programmer controlled inlet valve
opening.
In the event of a clogged drain, operator
intervention to skip the drain pump cycle, timer
malfunction or drain pump failure, provision must be
made for immediate inlet valve closing to prevent
overfill. Overfill protection for water filling of khe
tub has heretofore been provided by employing a float
having an actuator rod passing through an open tube in
the bottom of the washing tub for actuating a switch in
series with the solenoid valve for closing the water
inlet valve.
The disadvantage of the float actuated s~"itch is
that it requires an open tube be installed in the bottom
of the water tub which provides a potential source of flooding
in the event of malfunction of -the float or switch; and,
-thus an inheren-t danger of electrical shorting e~ists in
the event water should exit the float switch actuator tube.
The present invention provides a solution to
the above described problem of providing a con-trol system
which automatically controls the volume fill of water in
lG the washing receptacle so as to effect proper washing over
a wide range of soil conditions for the articles to be
washed, and variations in water supply pressure.
The presen-t invention provides for water filling,
for example until there is sufficient pressure to the washing
spray nozzles, which automatically provides extra water
when needed and a reduced amount of water if w~sh conditions
warrant. The present invention permits elimination of
the float, switch and open tube through the bottom of the
tub thereby eliminating a leakage path. elimination of
the float and open tube also simplifies washing rack design
since float clearance is no longer required. Optionally,
however, the float may be retained for redunda.nt overfill
protection if desired.
According to one aspect of the present invention
there is employed an electromagnetically actuated water
inlet valve for filling the washing receptacle which is
electrically in series with the recirculation pump motor
which empties the dirty wash and rinse water and provides
spray ~or the washing function. The electxomagnetically
actuated inlet valve may employ a solenoid coil having
a primary ~rmature activated by normal programmer/timer
coil energization for a predetermined washing cycle. The
recirculation pump has its inlet receiving the full head
of water in the tub and the discharge heaa of the recirculation
pump may be sensed to provide a command signal for actuating
a movable pole piece in the electromagnetic valve for disabling
the valve opening armature -thereby causing the wate.r inlet
valve to close. The present invention thus provides a
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fluid pressure actuated means Eor disabling the wa-ter inlet
solenoid valve when it is normally energized by the pro~
grammer/timer.
The present invention thus provides a unique
control system for a household dishwasher which provides
for automatic closing of the water inlet valve when the
desired pressure is attained in the washing water jet circuit
from the pump outlet. Overfill protection is automatically
provided in the event of an open circuit motor since the
motor is in series with the inlet valve. ~n optional feature
provides a secondary armature operable to close the inlet
valve automatically in the event of a locked-rotor condition
in the recirculation pump motor. The programmer/timer
may also shut off the inlet valve as in prior art systems.
According to another aspect of the present invention,
there is provided a water fill control system for an automatic
washe^ having a tub in which articles ar~ placed for ~7ashinc~.
The system includes fill means having electromagnetically
actuated valve means for connection to a source of pressurized
~0 water, the valve means being operable upon electrical ener- -
gization for magnetically effecting movement of an armature
for admitting water to the tub from the source and upon
deenergization to stop water flow from the source to the
tub. -The valve means includes a moveable magnetic pole
piece and force actuator means operable upon receipt of
a fluid pressure signal to apply the press~re to move the
pole piece for defeating magnetomotive force to ca~lse the
valve means to stop flow of water when t~e valve means
is in the electrically energized condition. Programmer
means is provided which includes switch means operable
to connect the valve electrical means to the source of
power in accordance with a preselected program with means
being provided for sensing the pressure head o~ water in
the tub and operable to provide the fluid pressure signal
upon the water head rising above a desired level.
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BRIEF DESCRIPTION OF THE DR~WINGS:
FIGURE 1 is a perspective view of a household
washing machine witll portions o the cabinet broken away
to show the interior components;
5FIGURE 2 iS a schematic of the control system
employed in the machine of Figure l; and
FIGURE 3 is a cross-sectional view o the
electromagnetically operated water fill valve of the
10 system of Figure 1.
DETAILED DESCRIPTION:
Referring n.ow to Figure 1, a dishwashing machine of
15 the type employed in domestic households for operation
on a source of alternating current electrical power and
connection to the household water supply is indicaked
generally at 10 as having a washing receptacle or tub 12
with a recirculating pump 14 having the inlet 16 thereof
20 connected to a port 18 provided in the bottom of the tub
12. The discharge outlet 20 of the pump is connected
via conduit 22 to the inlet of a rotating spray bar ~4
having a plurality of discharge orifices 26 provided
thereon for directing washing water to the articles
25 received in the tub.
An electromagnetically actuated filling valve 30 i~
provided adjacent the upper rim of the tub 12 and is
electrically connected for actuation to an electrical
programmer/timer 32 which has a manually settable
30 control knob 34 provided on the front of the dishwasher
for the convenience of the machine operator.
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The inle~ valve 30 has in the inlet thereof
connected to the household supply line (not shown) with
the outlet connected to a fill spout or tube 36 which
directs water flow into the tub 12 upon opening of the
valve 3~. The water inlet valve 30 has a sensing port
connection 38 which is connected via tube 40 to a pump
discharge tap 42 for sensing pump discharge pressure.
As will be hereinafter described, the signal through
tube 40 effects closing of the valve 30 when the desired
10 pump discharge or pressure has been attained. As a
backup in the event of a malfunctionf programmer/timer
32 will also close valve 30 ~lectrically.
Referring now to Figure 2, the control system of the
present invention is represented schematically wherein
15 programmer/timer 32 is shown as having a timing motor 44
driving, through an intermediate drive 46 comprising a
gear reduction train, a rotary cam 48. A cam follower
50 is connected to a movable contact arm 52 of a single
pole double throw switch indicated generally at 54.
Switch 54 has the movab1le contact arm 52 connected
via lead 56 to junction 58 which is connected to one
terminal of motor 44 and to one side of the household
power line Ll.
The rem~ining terminal 60 of the timing motor is
connected via lead 62 and junction 64 to the opposite L2
of the household power line.
Switch 54 has one contact 66 thereof connected via
lead 6~ to one connecting terminal 70 of inlet valve
30. The opposite contact 72 of switch 54 is connected
via lead 74 to junction 76 and one terminal 78 of pump
14. The opposite terminal 80 of pump 14 is connected to
side L2 of the household power line. The switch 54 thus
has one circuit thereof in series with water inlet valve
30 and the other circuit in series with pump 14.
Water inlet valve 30 has a solenoid coil 82
connected at one end to terminal 70 and at the opposite
end to terminal 84 which is connected via lead 86 to
power lead junction 76. The switch 54 thus has one
circuit thereof through contact 66 in series with water
inlet valve coil 82 and the other contact 72 thereof in
series with pump 14.
Referring now to Figure 3, the electromagnetically
actuated water inlet valve 30 has the coil 82 mounted on
10 a base plate or ~upport frame 84 attached to the body 86
oE the valve in any suitable manner. The details of
such atachment have been omitted in Figure 3 for
simplicity.
The valve 30 is of the pilot actuated type known in
15 the art as having a pilot valve seat indicated generally
at 88 and a main valve seat indicated generally at 90
against which rests the pressure responsive diaphragm
92. In the present practice, water filling rates of
4-12 liters/minute have been found suitable for
20 dishwasher applications~ However, the flow rate will be
understood to be determined by the amount of water
desired in the machine tub. The diaphragm and valve
seat member 88 inclllde a bleed passage 9~ fvr providing
pressure equalization on both sides of the diaphragm.
25 Valve body 86 has an inlet passage 96 communicating with
the main valve 90~
Valve 30 includes a primary armature 98 formed ~f
ferr~magnetic ma~erial and having pilot valve member 100
provided in the end thereof for closing pilot valve 88c
In operation, with the valve closed as shown in
Figur~ 3, upon energization of coil 82, armature 98 is
moved upward to permit water from inlet 96 connected to
chamber 97 having passed through bleed hole 94 to pass
outwardly through passaye 102 provided in the main valve
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dîaphragm 92 wh.ich causes a pressure drop above
diaphragm 92; and, pressure from inlet 96 then causes
the diaphragm to move upwardly thereby opening main
valve 90. The outlet 104 of inlet valve 30 is connected
to water fill nozzle tube 36 tsee Fig. 1).
Referring again to Figure 3, primary armature 98 is
received in a water tight guide 106 which has the lower
end thereof engaging the outer periphery of the
diaphragm 92 in fluid pressure sealing engagement and
10 which is retained therein by plate 84. An armature
return spring 108 registers on one end against the upper
end of yuide 106 and at its lower end against the top of
primary armature 98 thus urging the armature downward so
that pilot valve member 100 is in contact with valve
15 seat 88 in the coil deenergized condition.
The armature guide 106 has received thereover
stationary ferromagnetic pole member 110 and movable
upper pole piece 112 which, in the valve deactuated
condition, is spaced Erom member 110 by an amount
20 comprising a suitable air gap 114 which upon
energization of coil 82 causes primar~ armature 98 to
move upward to a null position with respect to gap 114
thereby opening pilot valve 88.
Pole piece 112 is movable vertically within the coil
25 from a position as illustrated in Figure 3 defining air
gap 114, to a downward position contacting the upper
surface of pole piece 110, in which position no air gap
exists. A suitable spring 114 having one end thereof
registering against the upper surface of the armature
guide and the other end registering against the
undersurface of the upper end of pole piece 112 urges
the pole piece upwardly to a position defining air gap
114.
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With continuing reference to Figure 3, a ~econdary
ferro~agnetic armature 116 having a generally ~up-shaped
configuration i~ received ~ver the coil. The
undersurface 120 of the upper end of armature 116 is
registered against the URper end of ~ole piece 112 and
ha~ an apPrature 122 form@d therethrough.
A compression 5pring 124 i5 receiYed over the pole
piece 112 and h~s the upper ~nd thereof registered
against the under~urface 120 of the ~econdary armature;
10 and, the lower end i~ registered against the top of the
~oil for urgin~ the secondary armature 116 in an upward
direction.
A pressure responsive actuator indicated generally
at 126 ifi positioned by ~uitable mounting (not shown) to
15 base plate ~4 fo~ p~oviding actuation of the movabl2
pole piece 112. The pres~ure responsive actuator has a
housing 128 with sensing p~rt 38 formed in the upper
~urface thereof which port has sensing tube 40 ~see Fig.
1) connected there~o for providing a fluid command
20 signal from the discharge ~ide of pump 1~.
Sensing ~ 38 may ~e provided with an orifice
restri~tion and the conf iguration vf housing 138 can be
adjusted t3 compen ate ~or i.rregularities in pump output.
The interior oE housing 128 is divided by a flexible
25 diaphragm 130 ~ealed about its periphery to the outer
rim of the housing to- form - an upper pre~sure c:hamber
conrlected to port 38 ana a lower chamber vented to the
atmosphere through a t:ontrolled vent or ~e~led chamber
tc~ provide damping of pump output variationsO
The under~iae of diaphragm 13Q has a ~ui~able
backing pla~e 132 provided in the central region thereof
which plate contact~ one end of an actuator rod 134
extending downwardly ~hrough armature 122 with the lower
end thereof reg;~tered against the upper suracP ~f
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movable pole piece 112. A biasing spring 136 has the
upper end thereof registered against backing plate 132
and the lower end registering against a shoulder 138
provided in housing 130. Spring 136 thereby effects
biasing of the diaphragm in an upward direction. The
spring 136 is chosen such that a predetermined pump
output pressure must act on diaphragm 130 to cause
operable downward movement thereof. In the present
practice of the invention the spring 130 is overcome at
10 pressures of 3~8 psl acting on the diaphragm.
In operation, with the valve in the closed position
and coil 82 deenergized, as shown in Figure 3, pole
piece 112 is in its uppermost position and armature 98
is contacting valve seat 83 with diaphragm 92 seated on
15 main valve seat 90. Secondary armature 116 is in its
uppermost position in registration with the undersurface
of housing 12~.
Upon energization of coil 82 by the programmer~timer
32 for normal dishwasher operation, armature 98 moves
20 upward opening pilot valve 88 which permits main valve
90 to open and water to flow from the inlet 9~ through
outlet 104 and fill tube 36 inl:o the washing tub.
When the pressure output of the pump 14 has attained
the desired level for washing, the pressure is
25 transmitted through tube 40 and sensed by the pressure
responsive actuator 126. With valve coil energized and
valve 30 open as fluid pressure from the pump is applied
to diaphragm 130, actuator rod 134 is moved downward
through aperture 122 in the secondary armature, which
30 remains motionless, and actuator rod 134 moves movable
pole piece 112 downwardly to close air gap 114 which
renders the magnetic orce upon the armature nil so that
return spring 108 closes the pilot valve 88 thereby
causing closure of main valve 90 and cession of water
35 flow through fill tube 36.
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Alternatively, in the event tha-t a locked rotor con-
dition occurs in pump 14 with the inlet valve 30 open, the
increased current flowing through coil 82 generates suf-
~icient magnetic force to cause secondary armature 116 to
overcome spring 124 and move downward thereby moving movable
pole piece 112 to close air gap 114.
From the foregoing description it will be seen that
when the solenoid coil 82 is energized by programmer/timer
32 for filling of the tub during normal washing operations,
the occurrence of either (a) sufficient pump discharge
pressure for normal washing; or (b) locked rotor current
will cause the movable pole piece 112 to be moved downward
closing air gap 114 to thereby effect closing of the inlet
-~al-~e 30.
The novel control system of the present invention has
herein been described in its ~referred form as having a
solenoid actuated water inlet valve wherein a movable pole
piece member is actuated by a pressure responsive diaphragm
upon occurrence of sufficient water pressure at the pump
outlet to defeat electromagnetic actuation of the inlet
valve. The present invention also optionally employs a
secondary armature for the solenoid operator which secondary
armature is responsive only to excessive current caused by a
locked rotor in the pump, which is electrically in series
with the solenoid coil; and, the secondary armature in-
dependently. moves the movable pole piece to eff~ct closing
of the water inlet valve.
Although the invention has hereinabove been described
in its preferred form as applied to an automatic dishwasher
it will be apparent to those skilled in the art that the
control system is applicable to automatic clothes ~ashers
using static -tub water
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head, and, other modificat.ions and variations to the
invention may be made with the invention being limited
only by the following claims.
I CLAIM:
