U.S. patent number 3,888,269 [Application Number 05/380,102] was granted by the patent office on 1975-06-10 for control system for dishwasher.
This patent grant is currently assigned to Whirlpool Corporation. Invention is credited to Larry Thomas Bashark.
United States Patent |
3,888,269 |
Bashark |
June 10, 1975 |
Control system for dishwasher
Abstract
A dishwasher having a single control pushbutton adapted to
perform a multiplicity of different dishwashing and dish treating
operations. The dishwasher includes an improved automatic control
which has the capability to determine an optimum treatment of the
dishes in the dishwasher based on the condition of the dishes when
they are in the dishwasher. The control not only causes the
dishwasher to effect an amount of washing of the dishes necessary
to substantially fully clean the dishes irrespective of the
condition of the dishes when placed therein, but also may
automatically cause the dishes to be merely rinsed and dried where
the dishes are only dusty and no washing is required. Structure for
receiving suitable charges of dishwashing detergent and the like
are incorporated in the dishwasher and the control responds
includes means for responding to the provision of such detergent
for automatically effecting use of the detergent at the appropriate
time in the dishwashing cycle. The control further automatically
senses the cleanliness condition of the dishes at the end of each
subcycle and automatically controls the length of the drying cycle
so as to terminate the drying cycle substantially immediately upon
completion of the drying of the dishes.
Inventors: |
Bashark; Larry Thomas (St.
Joseph, MI) |
Assignee: |
Whirlpool Corporation (Benton
Harbor, MI)
|
Family
ID: |
23499907 |
Appl.
No.: |
05/380,102 |
Filed: |
July 17, 1973 |
Current U.S.
Class: |
134/57D;
68/12.18; 68/12.27; 68/12.15; 68/12.22; 134/113 |
Current CPC
Class: |
D06F
34/22 (20200201); A47L 15/4297 (20130101); A47L
15/0047 (20130101); A47L 2501/30 (20130101); A47L
2501/02 (20130101); A47L 2501/11 (20130101); A47L
2401/09 (20130101); A47L 2401/10 (20130101); A47L
2501/06 (20130101); A47L 2501/01 (20130101) |
Current International
Class: |
A47L
15/42 (20060101); D06F 39/00 (20060101); B08b
003/02 () |
Field of
Search: |
;134/570,113
;68/12R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bleutge; Robert L.
Attorney, Agent or Firm: Hofgren, Wegner, Allen, Stellman
& McCord
Claims
I claim:
1. In a dishwasher having means defining a chamber for holding
dishes to be washed, means for providing water fills to said
chamber, means for pumping the water against the dishes in the
chamber, means for draining the water from the chamber, and means
for heating the chamber to dry dishes therein, structure
comprising:
means defining a liquid collecting receptacle communicating with
said chamber;
sensing means for selectively sensing the turbidity of a water fill
in the chamber and the depth of a collected portion of the water
fill in said receptacle; and
control means responsive to said sensed turbidity and depth for
controlling the dishwashing operation to operate seriatim said
water providing means to effect a first fill of the chamber,
operate said pumping means to rinse the dishes with the fill water,
interrupt the rinse and operate said sensing means to determine the
turbidity of the rinse fill water, operate the pumping means to
complete the rinse with said fill water, operate the draining means
to remove said fill water from the chamber, and selectively
a. in the event the level of the sensed turbidity is at or above a
preselected level operate said water providing means to effect a
second fill of the chamber, operate said pumping means to rinse the
dishes with the second fill water, operate the draining means to
remove the second fill from the chamber, and permit the dishes to
air-dry, or
b. in the event the sensed turbidity is below said preselected
level operate said heating means to heat dry the dishes in the
chamber and evaporate fill water from said receptacle, and
terminate the heating step when the sensed depth of fill water in
said receptacle drops to a preselected level.
2. In a dishwasher having means defining a chamber for holding
dishes to be washed, means for providing water to said chamber,
means for pumping the water against the dishes in the chamber,
means for draining the water fills from the chamber, means for
heating the chamber to dry dishes therein, and a cup having a lid
and means for releasably locking the lid in a disposition closing
the cup for releasably holding detergent which when dispensed into
the chamber forms with a water fill a detergent solution for
washing the dishes therein, structure comprising:
means defining a liquid collecting a receptacle communicating with
said chamber;
sensing means for selectively sensing the turbidity of a water fill
in the chamber and the depth of a collected portion of the water
fill in said receptacle;
means for sensing the disposition of the detergent cup lid; and
control means responsive to said sensed turbidity, fill depth, and
lid position for controlling the dishwashing operation to operate
seriatim said water providing means to effect a first fill of the
chamber, in the event the detergent cup lid is disposed to close
the cup operate said pumping means to provide a complete first
rinse of the dishes with the fill water, operate the draining means
to remove said fill water from the chamber, operate said water
providing means to effect a second fill of the chamber, operate
said pumping means to initiate a second rinse of the dishes,
interrupt the rinse and operate the sensing means to determine the
turbidity of the second rinse fill water, selectively
a. in the event the sensed turbidity of the second fill water is
below said preselected level, release said cup lid to open the cup
and deliver detergent from the cup into the second fill water for
forming a detergent washing solution, operate said pumping means to
effect a washing of the dishes therewith, operate said draining
means to remove the washing solution from the chamber, operate said
waterproviding means and pumping means to effect a further rinsing
of the dishes, and operate said heating means to heat dry the
dishes in the chamber and evaporate fill water from said
receptacle, and terminate the heating step when the sensed depth of
fill water in said receptacle drops to a preselected level; or
b. in the event the sensed turbidity of the second fill water is at
least a preselected level operate said pumping means to complete
the second rinse of the dishes, operate the draining means to
remove the second rinse fill water from the chamber, operate said
pumping means to initiate a third rinse of the dishes, interrupt
the rinse and operate the sensing means to determine the turbidity
of the third rinse fill water, selectively
c. in the event the sensed turbidity of the third fill water is at
least said preselected level operate said pumping means to complete
the third rinse of the dishes, operate the draining means to remove
the third rinse fill water, operate said water-providing means to
effect a fourth fill of the chamber, release said cup lid to open
the cup and deliver detergent from the cup into the fourth fill
water, operate said pumping means to effect a washing of the
dishes, operate said draining means to remove the washing solution,
operate said water-providing means and pumping means to effect
further rinsing of the dishes, operate said heating means to heat
dry the dishes in the chamber and evaporate fill water from said
receptacle, and terminate the heating step when the sensed depth of
fill water in said receptacle drops to a preselected level; or
d. in the event the sensed turbidity of the third fill water is
below said preselected level, release said cup lid to open the cup
and deliver detergent from the cup into the third fill water for
forming a detergent solution, operate said pumping means to effect
a washing of the dishes, operate said draining means to remove the
washing solution, operate said water-providing means and pumping
means to effect further rinsing of the dishes, operate said heating
means to heat dry the dishes in the chamber and evaporate fill
water from said receptacle and terminate the heating step when the
sensed depth of fill water in said receptacle drops to a
preselected level.
3. The dishwasher structure of claim 2 wherein means are provided
for introducing detergent into the first fill water to form a
detergent solution for washing the dishes during the first pumping
operation.
4. In a dishwasher having means defining a chamber for holding
dishes to be washed, means for providing water fills to said
chamber, means for pumping the water against the dishes in the
chamber, means for draining water from the chamber, means for
heating the chamber to dry dishes therein, and a cup having a lid
and means for releasably locking the lid in a disposition closing
the cup for releasably holding detergent which when dispensed into
the chamber forms with a water fill a detergent solution for
washing the dishes therein, structure comprising:
means defining a liquid collecting receptacle communicating with
said chamber;
sensing means for selectively sensing the turbidity of a water fill
in the chamber and the depth of a collected portion of the water
fill in said receptacle;
means for sensing the disposition of the detergent cup lid; and
control means response to said sensed turbidity, depth, and lid
position for controlling the dishwashing operation to operate
seriatim said water-providing means to effect a first fill of the
chamber, in the event the detergent cup lid is diposed to close the
cup operate said pumping means to provide a complete first rinse of
the dishes with the fill water, operate the draining means to
remove said fill water from the chamber, operate said
water-providing means to effect a second fill of the chamber,
operate said pumping means to initiate a second rinse of the
dishes, interrupt the rinse and operate the sensing means to
determine the turbidity of the rinse fill water, selectively
a. in the event the sensed turbidity of the second fill water is
below said preselected level, release said cup lid to open the cup
and deliver detergent from the cup into the second fill water for
forming a detergent washing solution, operate said pumping means to
effect a washing of the dishes, operate said draining means to
remove the washing solution, operate said water-providing means and
pumping means to effect a further rinsing of the dishes, operate
said heating means to heat dry the dishes in the chamber and
evaporate fill water from said receptacle, and terminate the
heating step when the sensed depth of fill water in said receptacle
drops to a preselected level; or
b. in the event the sensed turbidity of the second fill water is at
least a preselected level, operate said pumping means to complete
the second rinse of the dishes, operate the draining means to
remove the second rinse fill water, operate said water-providing
means to effect a third fill of the chamber, operate said pumping
means to initiate a third rinse of the dishes, interrupt the rinse
and operate the sensing means to determine the turbidity of the
third fill water, or selectively
c in the event the sensed turbidity of the third fill water is at
least said preselected level operate said pumping means to complete
the third rinse of the dishes, operate the draining means to remove
the third rinse fill water, operate said water-providing means to
effect a fourth fill of the chamber, release said cup lid to open
the cup and deliver detergent from the cup into the fourth fill
water, operate said pumping means to effect a washing of the
dishes, operate said draining means to remove the washing solution,
operate said water-providing means and pumping means to effect
further rinsing of the dishes, operate said heating means to heat
dry the dishes in the chamber and evaporate fill water from said
receptacle, and terminate the heating step when the sensed depth of
fill water in said receptacle drops to a preselected level, or
d. in the event the sensed turbidity of the third fill water is
below said preselected level release said cup lid to open the cup
and deliver detergent from the cup into the third fill water for
forming a detergent solution, operate said pumping means to effect
a washing of the dishes, operate said draining means to remove the
washing solution, operate said water-providing means and pumping
means to effect further rinsing of the dishes, operate said heating
means to heat dry the dishes in the chamber and evaporate fill
water from said receptacle, and terminate the heating step when the
sensed depth of fill water in said receptacle drops to a
preselected level, or further alternatively,
e. in the event the detergent cup lid is not disposed to close the
cup at the time of the first fill seriatim, operate said
water-providing means to effect a first fill of the chamber,
operate said pumping means to rinse the dishes with the fill water,
interrupt the rinse and operate said sensing means to determine the
turbidity of the rinse fill water, operate the pumping means to
complete the rinse with said fill water, operate the draining means
to remove said fill water from the chamber, and selectively
f in the event the turbidity sensed in step (e) is at least a
preselected level, operate said waterproviding means to effect a
second fill of the chamber, operate said pumping means to rinse the
dishes with the second fill water, operate the draining means to
remove the second fill from the chamber, and permit the dishes to
air-dry, or
g in the event the turbidity sensed in step (e) is below said
preselected level, operate said heating means to heat dry the
dishes in the chamber and evaporate fill water from said
receptacle, and terminate the heating step when the sensed depth of
fill water in said receptacle drops to a preselected level.
5. The dishwasher structure of claim 4 wherein said sensing means
comprises a sensor responsive to light reflected from rinse fill
water in the chamber to provide a turbidity determination and to
light reflected from the underside of rinse fill water in said
receptacle to provide a dryness determination corresponding to the
depth of water in the receptacle.
6. The dishwasher structure of claim 4 wherein said control means
includes a switch for manually initiating the said series of
operations and means for selectively effecting each of the said
alternative series of operations to completion without additional
manual input.
7. In a dishwasher having means defining a chamber for holding
dishes to be washed, means for providing water fills to said
chamber, means for pumping the water against the dishes in the
chamber, means for draining water from the chamber, means for
heating the chamber to dry dishes therein, and a cup having a lid
and means for releasably locking the lid in a disposition closing
the cup for holding detergent to be dispensed into the chamber to
form with a water fill a detergent solution for washing the dishes
therein, the improvement comprising: a sensing element for sensing
the turbidity of a water fill and a dryness condition; and control
means responsive to a single operation-initiation manipulation, and
dryness conditions obtaining as a result of the dishwashing
operations for seriatim effecting pre-wash rinse operation until
said sensing means senses a turbidity less than a preselected
amount, wash, post-wash rinse, and drying operations until said
sensing means senses a preselected resultant dryness condition.
8. The dishwasher structure of claim 7 wherein said sensing means
comprises means responsive to different reflective agencies of the
fill water to sense selectively the turbidity and dryness
conditions.
9. The dishwasher structure of claim 7 wherein means are provided
for effecting a wash operation prior to the initial rinse
operation.
10. The dishwasher structure of claim 7 wherein said control
includes means for determining the turbidity of fill rinse water
after a preselected amount of rinse operation and causing the
dispensing of the detergent from said cup into the rinse water to
convert the rinse operation to a wash operation in the event the
sensed turbidity is less than said preselected amount.
11. In a dishwasher having means defining a chamber for holding
dishes to be washed, means for supplying a charge of water to said
chamber, means for contacting dishes in the chamber with dish
treating liquid, means for draining water from the chamber, and
means for dispensing detergent into the chamber to form with a
water charge a detergent solution for washing dishes therein, the
improvement comprising: a sensing element for sensing the turbidity
of a water fill and a dryness condition; and control means
responsive to a single operation-initiation manipulation, and the
sensed turbidity and dryness conditions obtaining as a result of
the dishwashing operations for seriatim effecting pre-wash rinse
operation until said sensing means senses a turbidity less than a
preselected amount, wash, post-wash rinse, and drying operations
until said sensing means senses a preselected resultant dryness
condition.
12. The dishwasher structure of claim 11 wherein the control means
is programmed to check periodically if the sensing means is
functioning properly, and to provide a fail safe alternative cycle
including a timed dry period in the event that the check of the
sensing means determines that it is not functioning properly.
13. The dishwasher structure of claim 11 wherein said control means
includes only a single control button for effecting automatically
as a result of said single manipulation the different dish treating
operations as may be required, depending on the sensed condition of
the dishes when they are in the dishwasher.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to washing apparatus, and in particular, to
dishwashers.
2. Description of the Prior Art
In the conventional dishwasher, a timer control is provided which
cycles the diswasher to provide different dishwashing functions.
For example, the timer effects a preselected pre-rinse cycle, a
plurality of wash cycles, one or more post-rinse cycles, and a dry
cycle, the duration of each of which is controlled by the timer
clock means. As the dishwasher may be used for different operations
in treating the dishes, such as rinse only, rinse-dry, light wash
or heavy wash, or heat only, it has been conventional to provide a
plurality of pushbutton controls or selector means for manipulation
by the user to effect the desired specific dish treatment
cycle.
The use of such timer controlled devices presents a number of
disadvantages. The user may inadvertently set the control wrong for
the desired operation either by not recognizing the need for a
different operation in connection with the particular dishes being
treated or by accidentally pushing the wrong button or setting the
selector control in the wrong mode. Further, because the drying
cycle is time controlled, the cycle is conventionally set for the
longest drying time necessary for the varying conditions to which
the dishwasher may be subject and a substantial amount of drying of
dishes may extend the drying time substantially beyond the time
necessary to complete the drying of the particular dish load
thereby wasting electrical power and unnecessarily heating the
kitchen space or other area in which the dishwasher is located.
Where the dishwasher is being used in a warm or hot area, such
wasted heat further taxes air conditioning equipment or raises the
temperature of the kitchen space providing a less comfortable
working condition.
Where an unnecessary number of washing steps is caused to be
effected by the user, the dishwashing may further be wasteful of
water and electrical power necessary to heat the water to the
relatively high temperatures normally used in dishwashers. Where
the user sets the dishwasher for a washing cycle which is
insufficient to clean the particular batch of dishes, the dishes
may be dried with food and other particles remaining adhered
thereto, making the subsequent food soil removal extremely
difficult.
It is further desirable to minimize the amount of detergent used to
wash the dishes, particularly for ecological reasons.
In one form of prior art washing structure, as shown in the United
States Letters Patent to Morey et al 3,114,253 for an "Automatic
Washing Machine Having Means to Measure the Rate of Change of
Turbidity," a control is provided for measuring the turbidity of
the wash liquid.
In United States letters Patent to Sones et al 3,279,481, a
dishwasher is shown having means for varying the speed of the fluid
distributing pump to vary the quantity and pressure of washing
fluid directed against the articles to be cleaned. In this patent,
a turbidity sensor is used to determine the turbidity of the rinse
water. The control further uses a timer controlled switch to
control the drying operation and means for varying the speed of the
air moving means to vary the drying effect as a function of the
sensed humidity.
United States Letters Patent to Clark 2,218,698 for a Washing
Machine illustrates the use of a photocell means responsive to the
change in light received thereby when the suds level raises to a
preselected level in the apparatus.
United States letters Patent 2,430,668 to J. W. Chamberlin shows a
washing machine and automatic control mechanism therefor wherein
the different batches of clothes being washed in the machine
provide different signals to the sensing means for varying the
washing operation depending on the soil conditions thereof.
United States letters Patent 3,477,258 to D. J. Walker et al shows
an electronic sequential control in a total sensing automatic
washer which effects cycling of the washer by a preselected time
delay or response to sensed conditions.
United States letters Patent 3,116,982 to O. T. McIlvaine shows a
photocell arrangement in a dryer exhaust for sensing the amount of
moisture therein to control the operation of the dryer.
Other U.S. Pat. Nos. which are of interest in connection with the
structural concepts of such timer controlled devices are those of:
Schoenberg 1,940,373; Robinson 2,503,770; St. Palley 2,771,892;
Skinner 2,968,688; Sharpe 3,013,400; Jacobs 3,070,714; Hill
3,074,277; Gawron 3,399,652; Eaton et al 3,504,184; Peube et al
3,511,572.
SUMMARY OF THE INVENTION
The present invention comprehends an improved dishwasher which
eliminates the need for the user to manually select the desired
operation of the dishwasher such as for short wash, medium wash,
super wash, rinse only, or rinse-dry operations. The present
invention permits the user to effect the proper treatment of the
dishes placed in the dishwasher by manual operation of a single
pushbutton. Where a washing rather than a rinsing operation is
required, the user places the necessary detergent in the
appropriate receptacle in the dishwasher prior to initiating
operation thereof and the control of the dishwasher automatically
effects the necessary amount of washing. The dishwasher
automatically terminates the dish treating operation upon
completion of the drying of the dishes by sensing different
conditions rather than relying on a time controlled drying cycle,
thereby minimizing the total time and energy expended in the dish
treating operation.
The control utilizes means for sensing the turbidity of the water
charge or fill in the dishwashing chamber automatically during the
dish treating cycle. The control further senses the depth of a
collected portion of the dish treating water in a receptacle
communicating with the dishwashing chamber. Control means are
associated with the dishwasher which are responsive to the sensed
turbidity and collected liquid depth to provide the above-described
desirable operation of the dishwasher. If the user wishes to wash
the dishes, the user places detergent in the detergent receptacle
in the dishwasher and closes an overlying lid associated with the
receptacle. If the user wishes to merely rinse only, or rinse-dry
the dishes, no detergent would be placed in the receptacle and,
thus, the lid would be maintained in the open position. Information
indicating the selective disposition of the lid is provided to the
control for use in regulating the operation of the dishwasher.
Relative to the treatment of the dishes without use of detergent,
the control is operated to sense the turbidity of the dish treating
liquid after the pump has been operating for a preselected period
of time such as after one minute of the first rinse period. To
sense the turbidity, flow of the dishwashing liquid is terminated
for a preselected period, such as 15 seconds, whereupon the
turbidity sensing means senses the turbidity of the liquid
collected above the sensor. If the dishwashing liquid is found to
be turbid, the dishwasher is operated to complete the rinse
operation such as to as to provide a total of a 5-minute rinse
followed by a 4-minute rinse with no dry period. This is the rinse
only cycle. Since the water was found to be turbid after 1 minute
of rinsing the dishes must have been soiled and it has been found
that the inclusion of the a dry period is not advantageous in this
case.
If the liquid is found to be not turbid during the sensing
operation, the control causes the completion of the first 5-minute
rinse and then a drying operation. This operation of the dishwasher
effectively comprises a rinse-dry or dry only operation as any dust
or the like which may be rinsed off will be removed by the treating
water, and if no dust or the like is present on the dishes, they
will be heated by the treating water and then dried in a shorter
cycle than would be required were the dishes heated only by the
electric drying means.
Where the user places detergent in the detergent cup, the first
turbidity sample is taken one minute after the second fill by
stopping the pump for a preselected period, such as 15 seconds, and
sensing the turbidity. Thus, for example, if it is found that the
rinse water is clear, the detergent is immediately dispensed so as
to convert the second fill from a rinse cycle into a wash cycle
inasmuch as the rinse is not removing material from the dishes to
make the water turbid. The completion of the dishwashing operation
would then include two 4-minute rinse cycles, and a sensor
controlled dry cycle. This is the four-fill, short wash cycle.
In one embodiment, the dishwasher may include a maintained open
detergent cup which can be used to convert the first water charge
from a rinse cycle into a wash cycle at the discretion of the user.
In either case, the sensing of the turbidity is effected in the
initial portion of the second cycle.
If the washing liquid is determined to be turbid by the sensing
means, the detergent is not dispensed at this time and the second
cycle rinse is continued as it is effecting removal of material
from the dishes. Subsequent water charges may be caused to be rinse
or wash cycles depending on the sensed turbidity so that a number
of additional rinse steps may be provided automatically under the
control of the sensing means depending on whether the rinsing steps
are removing material from the dishes so as to cause the sensed
liquid to be turbid during each of the several subsequent
cycles.
When the washing liquid is determined to be clear, indicating that
the rinse is no longer removing material from the dishes, the
closed detergent cup is automatically caused to open and change the
cycle from a rinse to a washing cycle, permitting the completion of
the dishwashing operation thereby as described previously in
connection with the four-fill cycle including two rinse fills
followed by a sensor controlled dry cycle.
In the preferred embodiment, a maximum of two turbidity sensings
are effected, namely, during the second and, if necessary, third
fill, so that if the treating liquid is turbid upon sensing of the
third fill liquid, the subsequent cycle is caused to be a washing
cycle notwithstanding to limit the total cycles to 6 in the
operation of the dishwasher.
The sensing means of the present invention is illustrated in
greater detail in my copending application Serial No. 380,101,
filed July 17, 1973, entitled "Sensor For Dishwasher," (PA-4654).
Said application is incorporated by reference herein and may be
referred to for a detailed description of the structure and
functioning of the sensing means. Briefly, however, the sensing
means includes means for directing light radiation upwardly into
dish treating liquid collected in a shallow receptacle
communicating with the dishwashing chamber. Means are provided for
sensing the light radiation reflected either from the solids
carried by the liquid above the receptacle to provide a turbidity
determination, or reflected from the underside of the upper surface
of collected liquid in the receptacle to provide the dryness
determination. Thus, the same sensor is used for determining the
turbidity condition of the rinse water as to determine the number
of cycles to be effected in the dishwasher, as well as to determine
the dryness condition of the dishes in the final, drying cycle as a
function of the decrease in the quantity of water remaining in the
shallow collecting receptacle. The decrease in the depth of this
collected water is caused by the drying action of the heating
element in the dishwasher chamber, the receptacle being in
communication with the chamber so as to cause evaporation of the
collected water at a rate proportional to the rate of drying of the
dishes in the chamber.
Thus, the dishwasher of the present invention provides effectively
maximum efficiency in the dishwashing operation in providing only
the necessary number of cycles, thereby minimizing use of washing
liquid and heat energy in heating the washing liquid to the washing
temperature. Further, maximum efficiency is obtained by limiting
the drying operation only to that necessary to complete the drying
of the dishes, thereby again avoiding unnecessary energy use in the
drying of the dishes as occurs in conventional dishwashers where
the drying cycle is timer controlled.
Another object of the invention is to provide a control which
performs periodic diagnostic checks on the sensor to determine if
the sensor is functioning properly, with reversion of the control
to a pre-programmed fail safe rinse and wash cycle with a timed dry
period if during the check the sensor is found to be not
functioning properly.
BRIEF DESCRIPTION OF THE DRAWING
Other features and advantages of the invention will be apparent
from the following description taken in connection with the
accompanying drawing wherein:
FIG. 1 is a fragmentary perspective view of a dishwasher having a
control embodying the invention;
FIG. 2 is a front elevation of the dishwasher;
FIG. 3 is a front vertical section illustrating the sensing means
in association with a sump portion of the dishwashing chamber
means;
FIG. 4 is a fragmentary enlarged vertical section of the sensing
means;
FIG. 5 is a top plan view thereof;
FIG. 6 is a schematic wiring diagram of the control; and
FIG. 7 is a block diagram illustrating the selective functioning of
the dishwashing apparatus as effected by the control.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the exemplary embodiment of the invention as shown in the
drawing, a dishwasher generally designated 10 is shown to comprise
a cabinet 11 defining a washing chamber 12 having a front opening
13 which is selectively closed by a front door 14. The dishes to be
washed may be carried on suitable racks 15 in chamber 12. The door
may be provided on its front surface with a handle 16 for swinging
the door between the closed position of FIG. 2 and the open
position of FIG. 1. A single pushbutton start switch 17 of the
momentary switch type is mounted on the door to provide for manual
control of the operation of the dishwasher. On its inner surface,
the door carries a conventional silverware basket 18 and a pair of
detergent cups 19 and 20. As illustrated schematically in FIG. 2, a
normally open lid switch 21 is associated with detergent cup 19 so
as to be closed as the result of a closing of the lid 19a after a
suitable quantity of detergent is placed in the cup 19 by the user.
Cup 20 may comprise an open cup whereby placement of detergent
therein causes the first cycle of operation of the dishwasher to be
a wash cycle if desired by the user.
As shown in FIG. 3, the dishwasher may further include a
conventional spray arm 22 for forcibly spraying the dishes carried
in the racks 15 in chamber 12. During the dish washing operation
the dishes may be contacted with rinse liquid or a washing liquid
including a detergent. A drying element in the form of a sheathed
electric resistance heating element 23 is provided in a sump
portion 24 of the tub 25 defining chamber 12 for heating the
chamber suitably to dry the dishes therein at the completion of the
dish treating operation.
As discussed above, operation of the dishwasher to effect a
substantial number of different dish treating operations is
effected herein automatically by the use of the single control
button 17. To provide such automatic functioning, the dishwasher
further includes a sensing element 26 which is adapted to determine
both the turbidity of the washing liquid and the dryness condition
of the dishwasher in different times in the operation thereof. As
indicated above, the sensor 26 is disclosed in my copending
application Ser. No. 380,101 in detail. For a complete
understanding of the present invention, however, it need merely be
understood that sensor 26, as best seen in FIG. 4, defines a
transducer including a light directing means 27, a light gathering
means 28 and means 29 defining a well or receptacle 30 for holding
a quantity of the dishwashing liquid at the bottom of chamber 12
after the remainder of the liquid has been pumped out of the
chamber 12. Portions 27 and 28 of the sensor consist of cylindrical
transparent glass or plastic windows and are connected by a body
portion 31. The cylindrical light directing means 27 and the
cylindrical light gathering means 28 have angular end portions
flush with the bottom of well or receptacle 30 to define a pair of
light openings 33 and 34 spaced apart a preselected distance. In
the operation of sensor 26, the motor is stopped so that the water
covers the sensor to a depth of about 1 inch. The sensing of the
turbidity of the liquid is effected by light radiation from a lamp
32 mounted in the sensor portion 27a passing upwardly through glass
window 27 and emanating from window 27 at the opening 33 and
reflected by the solid material which may be in the dishwashing
liquid L, back downwardly through opening 34 consisting of the top
end portion of window 28 to a photocell 35 mounted in the sensor 26
below light gathering means 28. The variation in the amount of
light reflected back to photocell 35 provides a variable resistance
signal corresponding to the turbidity of the liquid L above the
well 30.
In the operation of the sensor as a dryness sensing means, the
liquid L has been pumped out of the chamber 12 and light energy
from lamp 32 is reflected from the underside of the upper surface
of the liquid in well 30 to the photocell. The amount of light
varies substantially as the level of the liquid drops from the top
of the well during the drying operation so that the resistance of
the photocell varies substantially to provide a positive drying
cycle termination signal when the liquid level drops substantially
to the bottom of the well. The control 36 for the dishwasher is
illustrated in FIG. 6. The control is generally similar to that
shown in Joseph Karklys United States letters Patent 3,662,186,
issued May 9, 1972 for "Electronic Control Circuit for Appliances,"
which patent is incorporated by reference herein. The control 36
hereof differs from that shown in the Karklys patent in elimination
of a number of the input elements of the Karklys patent control and
the substitution therefor of the pushbutton start switch 17 and the
detergent cup lid switch 21. Thus, as shown in FIG. 6, switch 17
includes a first single pole, double throw switch 17a having a
first fixed contact 17b connected to ground and a second fixed
contact 17c connected to the negative supply voltage as will
appear. The moving contact 17d is connected to terminal M of the
control.
Switch 17 includes a second single pole, double throw switch 17e
having its moving contact 17f connected to terminal K, and one
fixed contact 17g connected to ground. Switch 17e is associated
with switch 17a so that the moving contacts are connected to ground
respectively in the different positions of the switch.
The detergent cup lid switch 21 comprises a single pole, single
throw switch having a fixed contact 21a (FIG. 6) connected to the
negative supply voltage and moving contact 21b connected to
terminal H of the control. A resistor 21c is connected from contact
21b to ground. The photocell 35 (FIGS. 4 and 6) of turbidity sensor
26 is connected between terminals P and R of the control 36. The
lamp 32 of sensor 26 is connected between the negative supply
terminal R and ground.
Thus, briefly, control 36 functions as follows. Control circuit 36
is energized from a suitable source as a 60H.sub.z AC power source
connected with terminals N (ground) and L1. An interlock switch 37
is connected between power lead 38 and terminal L1. This interlock
switch may be associated with the door 14 or handle 16 of the
dishwasher, breaking the power circuit when the door is opened,
thereby interrupting the energization of the dishwasher components
such as the pump motor, heater, solenoids, etc. The power supply
for a control circuit block 39 remains energized, but there is no
60 H.sub.z input to the clock portion of circuit 39 via resistor 40
and control circuit terminal T14, the status of control circuit
block 39 is maintained and when the dishwasher door is closed,
connecting power lead 38 to terminal L1 via interlock switch 37,
the dishwasher program will resume starting from the portion of the
program which was interrupted on opening of the door.
Several power switching circuits control the application of power
to functional elements of the apparatus. The circuit enclosed in
broken line box 41, which actuates the fill solenoid valve 42, is
typical. A driver transistor 43 has its base connected with control
circuit terminal T13 which provides a signal causing the transistor
to conduct when the fill solenoid 42 is to be energized. Transistor
43 is connected with the gate terminal of a bi-directional
current-conducting semiconductor 44 commonly known as a Triac.
Triacs, which are well known in the electronics art, normally
exhibit a high impedance between their end terminals and exhibit a
low impedance therebetween in response to the application of a
signal, having an amplitude greater than a predetermined magnitude,
to their third or gate terminal. When transistor 43 conducts, it
connects the gate of Triac 44 with a source of operating potential
to be described below. This causes the Triac 44 to conduct,
connecting the fill solenoid 42 from power line 38 to ground N.
Connected in series with fill solenoid 42 is an overfill limit
switch 45 which opens if the dishwasher is overfilled to a
predetermined level. Normally the actuation of fill solenoid 42 is
timed by the duration of the signal from control circuit block 39.
When the signal is not present, transistor 43 ceases conducting and
the power circuit through Triac 44 is broken.
The power supply for the various control circuits includes a
transformer 46 having a primary winding 46a connected across the
power line. Two rectifier circuits are connected with secondary
winding 46b. A half-wave rectifier diode 47 provides a negative
operating potential for control circuit 39. Capacitor 48, shunted
by series connected resistor 49 and zener diode 50 and returned to
ground N, filters the output of the rectifier Zener diode 50, which
is connected in parallel with a resistor 51, provides a regulated
output voltage at junction 52 for the control circuit 39. Power
input terminal T5 of circuit block 39 is connected with the anode
of zener diode 50 and terminal T1 is connected with ground N.
A timing reference input for control circuit 39 is obtained from
the 60H.sub.z power line through current limiting resistor 40
connected with control circuit terminal T14. A diode 53 is
connected from terminal T14 to the power supply junction 52
clamping the negative half-cycle of the input signal to provide an
essentially square wave drive for the timing circuit.
Diodes 54 and 55 are connected in a full wave rectifier circuit,
the output of which is filtered by capacitor 56. The circuit is
completed through transformer tap 57 of the portion of transformer
secondary winding 46b to which diodes 54 and 55 are connected. The
full wave rectifier circuit provides a negative operating potential
for the transistor drivers and the Triac gates of the switching
circuits which actuate the various elements of the apparatus. The
connection of transformer tap 57 to ground N, completing the
rectifier circuit, includes switching means which initiate and
terminates the operating cycle of the dishwasher.
Switching circuits 58 and 59, connected with terminals T12 and T11,
respectively, of control circuit block 39, operate Triacs 60 and 61
to control the operation of the pump motor 62 in the drain and
circulate modes. Motor 62 includes starting windings 62A which are
switched out during run by opening relay contacts 62b.
Switching circuit 63, connected with terminal T10 of control
circuit 39, operates Triac 64 to control energization of heater
23.
Switching circuit 65 operated from terminal T4 of the control
circuit, actuates Triac 66 controlling solenoid 67 which dispenses
wetting agent during the final rinse. Switching circuit 69
connected with control circuit terminal T3, actuates Triac 71 to
operate detergent dispensing solenoid 73 which opens lid 19a of
detergent cup 19.
Switching circuit 74 connected to control circuit terminal T2 and
Triac 75 is a part of the cycle control for the full wave
rectifier.
Various conditions of the dishwasher provide inputs to control
circuit 39 by connecting the control circuit terminals either with
ground N (logic 0) or negative power supply at junction 52 (logic
1). The photocell 35 of sensor 26 is connected to an analog to
digital signal conditioning circuit enclosed in broken line box 77
of FIG. 6. The digital output of the signal conditioning circuit 77
is connected to terminal T9 of control circuit 39. A resistor 78 is
connected between the negative supply junction 52 and the cathode
of silicon diode 80 and forward biases the two series connected
silicon diodes 79 and 80 thereby establishing a fixed reference
voltage at the emitter 76a of transistor 76. A resistor 81 is a
load resistor for transistor 76 and is connected between the
collector of transistor 76 and the negative supply junction 52. A
resistor 82 is connected between ground and the base of transistor
76. Transistor 76 conducts and provides a logic 0 at the input
terminal T9 of circuit 39 whenever the photocell 35 resistance is
below a fixed value, say 30K ohms. When the photocell 35 resistance
is above 30 K ohms transistor 76 is off and a negative voltage
(logic 1) is present at input terminal T9. The resistance of
photocell 35 is low when it is illuminated by light, and high when
the light level is low or absent. Hence, a logic zero is present at
input terminal T9 of control 39 when the turbidity of the
dishwashing liquid L is high or when the level of water in
receptacle 30 is high (dishes not dry). A logic one is present at
T9 when the dishwashing liquid L is not turbid or when the level of
water in receptacle 30 is low (dishes dry).
Control circuit 39 may be programmed to automatically interrogate
the sensor 26 to determine whether the sensor 26 is functioning
properly. During the last few seconds of each drain period a
considerable amount of light will be reflected from the surface of
the water trapped in receptacle 30 and will illuminate photocell 35
no matter whether the water is turbid or clear and a logic zero
will be present at terminal T9 if the sensor is functioning
properly. However, if the lamp 32 fails, or if the window surfaces
33 or 34 become abnormally coated with sediment the photocell 35
resistance will be high and a logic one signal will be present at
terminal T9. Thus the control circuit 39 can determine if the
sensor is not working and provide a suitable rinse or wash cycle
with a timed dry period if the sensor 26 is not working
properly.
Control 36 functions to provide automatically a number of different
operations of dishwasher 10 eliminating the need for multiple
pushbuttons to be selectively manipulated by the user to provide
the desired different operations. Thus, as shown in FIG. 7 the
operation of the dishwasher is effected by the user manipulating
pushbutton 17 to the "Start" position. If the detergent cup lid 19a
(FIG. 1) is not closed, this is indicated to the control by the
open condition of switch 21 (FIGS. 2 and 6). Under this condition,
the user would desire either a rinse only, or a rinse-dry cycle. As
indicated in FIG. 7, the first cycle under these conditions is a
fill of chamber 12 for 11/2 minutes followed by a pumping of the
washing liquid against the dishes by the spray arm 22 for 1 minute.
The spray is then discontinued for 15 seconds while the turbidity
dryness sensor 26 is utilized to determine the turbidity of the
water. If the turbidity so sensed is above a preselected amount,
control 36 causes a rinse only cycle to be completed by again
pumping the rinse water through spray arm 22 for an additional 4
minutes. At the end of this time, after a 4 second pause, the water
is drained in a 1 minute draining operation and a second charge of
rinse water is delivered to the chamber by a 11/2 minute delivery
operation. The water is then sprayed in a 4 minute spray cycle and
after a 4 second pause, this second quantity of rinse water is
drained in a 1 minute drain operation. Thereupon, the control
de-energizes the dishwasher.
If the turbidity of the rinse water sensed in the 15 second pause
of the first rinse cycle has a turbidity less than the preselected
turbidity, the control causes the cycle to be completed by a 4
minute spray operation followed by a 4 second pause and a 1 minute
drain. The control then determines whether the sensor is operating
properly as described above and if so the sensor is energized and a
dry cycle is initiated by energization of the heater 23. The drying
cycle is continued for 35 minutes, or until the sensor indicates
that the water level in well or receptacle 30 has dropped
substantially to the bottom of the well to indicate the completion
of the drying of the dishes, whichever occurs first. The dishwasher
is then de-energized to complete the operation. If the sensor is
not working properly, the drying cycle is established for the 35
minute period in the manner of the conventional time-controlled
drying dishwasher operation.
If the user closes the detergent cup lid 19a, indicating that
detergent has been placed in the cup for effecting a washing cycle,
the first cycle comprises a fill for 11/2 minutes, a pump spray
operation for 4 minutes, a pause for 4 seconds, and a drain of the
first rinse water for 1 minute. The second cycle is then
automatically initiated comprising a refill of the tub for 11/2
minutes, a pump spray for 1 minute, and a pause for 15 seconds,
during which time the turbidity dryness sensor is operated to
determine the turbidity of the second rinse water. If the second
rinse water turbidity is less than the preselected turbidity, a
four-fill cycle is completed by releasing the detergent cup lid to
deliver the detergent into the rinse water, thereby converting this
cycle from a rinse to a wash cycle. This wash cycle is then
continued with the second fill water for 4 minutes followed by a 4
second pause and a 1 minute drain. Two successive rinse operations
are then effected by a refill of the chamber for 11/2 minutes, a
pump spray for 4 minutes, a pause for 4 seconds, a drain for 1
minute, a refill of rinse water for 11/2 minutes, a pump spray for
4 minutes, a pause for 4 seconds, and a drain for 1 minute. The
completion of the washing operation then is effected by determining
whether the sensor 26 is functioning properly and effecting a final
drying operation as discussed above wherein the dishes are dried
either under the control of the sensor 26 or for a maximum periood
of 35 minutes.
If the turbidity determination made in the second rinse cycle
indicates that the water is turbid, the second rinse cycle is
continued as a rinse operation for 4 minutes followed by a pause
for 4 seconds, a drain of the second rinse water from the tub for 1
minute, and a refill of the tub with a third fill or charge of
water for 11/2 minutes followed by a pump spray for 1 minute. The
turbidity is then redetermined during a pause for 15 seconds, and
if the turbidity is now less than the preselected turbidity, the
operation is completed by a completion of the third fill as a wash
cycle by releasing the detergent cup lid to deliver the detergent
into the rinse water, thereby converting the third fill from a
rinse to a wash cycle. This wash cycle is then continued with third
fill water for 4 minutes followed by a 4 second pause and a 1
minute drain. A five fill cycle is then achieved by two successive
rinses and a dry period.
If the turbidity sensed during this second turbidity determination
is greater than the preselected turbidity, a third rinse cycle is
effected by completing the cycle subsequent to the turbidity
determination by a pump spray for 4 minutes, a pause for 4 seconds,
and a drain for 1 minute. Upon completion of the third rinse cycle,
the wash cycle is automatically initiated with fourth fill water by
filling of the tub with hot water for 11/2 minutes, opening the cup
lid, continuing the pump spray for 4 minutes with the water now
constituting a detergent solution to wash the dishes, pausing for 4
seconds, and draining the wash water for 1 minute. The completion
of the operation is then effected as above by providing two
additional rinse cycles and a dry cycle. Thus, the two additional
rinse cycles result in a six fill cycle.
In the event that the user places detergent in the cup 19 and
closes the lid, the dishwasher automatically effects and initial
rinse cycle, one or two subsequent rinse cycles, depending on
whether or not additional dirt is being removed from the dishes
during the first minute of the second rinse cycle, and
automatically initiating the wash cycle after either the first,
second or third rinse so provided, followed by automatically
providing two rinse cycles and a drying cycle. As discussed above,
the drying cycle may be under the control of the sensor 26 so as to
terminate the drying operation as soon as the dishes are dry,
which, depending on the ambient conditions, may be substantially
prior to the end of the maximum 35 minute drying period provided
for by the control. As only the number of pre-rinses is provided
wherein removal of dirt from the dishes is being effected, optimum
use of the hot water supply and operation of the dishwasher is also
effected in the dish cleaning operation.
As discussed briefly above, the detergent cup 20 may be an open cup
so that if the user also places detergent therein, the first dish
treating cycle may comprise a wash cycle, thereby automatically
providing in the operation of the dishwasher two dishwashing
cycles. The sensing of the turbidity is effected during the first
part of the second cycle which, at this point, comprises a rinse
operation as the detergent cup lid of cup 19 remains closed until
opened under the control of the turbidity sensor as discussed above
in the second, third or fourth dish treating cycle.
It has been found that at times the user selects an operation of a
dishwasher with a greater number of fill cycles than is necessary
to be sure that the dishes are effectively cleaned. The present
control eliminates such waste by assuring that only the necessary
number of fills is used.
As will be obvious to those skilled in the art, the amount of
drying can be adjusted at the time the sensor is manufactured by
altering the depth of the well 30. The pause required to permit the
making of the turbidity determination may also be varied as
desired. It has been found, however, that approximately 15 seconds
is desirable to permit the treating liquid to become quiescent in
the sump area, thereby assuring a proper sensing operation. It has
been found that the determination of the turbidity is substantially
unaffected by the presence of detergent in the washing liquid which
may carry over from a first wash cycle where detergent is placed in
the open cup 20.
As will be appreciated by those skilled in the art the single start
pushbutton 17 of the present invention may be employed to replace
five separate pushbuttons conventionally required for the following
cycles: Rinse Only, Rinse-Dry, and 4, 5, or 6 Fill Wash cycles. If
additional cycles or options are desired such as Dry Only, Hot
Rinse, Cancel & Drain, etc. these options may be provided by
including extra pushbuttons on the control panel without departing
from the spirit of the invention.
The dishwasher is extremely simple and economical of construction
while yet providing an improved simplified method of operation
effectively optimizing the energy use of the dishwasher in
effecting desirable treatments of the dishes not only for washing
purposes, but also for rinsing or heating purposes. Because of the
simplicity of the apparatus, long trouble-free life is
provided.
The foregoing disclosure of specific embodiments is illustrative of
the broad inventive concepts comprehended by the invention.
* * * * *