Method of selecting a wash cycle for an appliance

A method of selecting a washing cycle for an intelligent appliance uses several factors to make a cycle selection. The first factor is a combination of the water turbidity, conductivity and temperature as well as the wash arm speed. The other factors are the average of previously selected cycles, the number of times the appliance door has been opened, and the time between wash cycles. The appliance also allows the user to bump up the selected cycle to a higher cycle if the user is unsatisfied with the performance of the appliance. If a failure has occurred with any of the sensors or in the communications routine, the appliance selects the average of previously selected cycles as the wash cycle.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to automatic washing machines. More 
particularly the present invention relates to a method of automatically 
selecting a dishwashing cycle depending on a number of conditions. While 
the present invention is described as it applies to automatic dishwashers, 
it has equal applicability to all cycle controlled washing machines and 
other cycle controlled systems. 
2. Problems in the Art 
Prior art dishwashers typically have a number of user selectable 
dishwashing cycles. The user manually selects one of the cycles depending 
on what cycle the user feels is appropriate. For example, if the dishes in 
the dishwasher are not very dirty, the user might select a light washing 
cycle. On the other hand, if the dishes are very soiled, the user might 
pick a heavy wash cycle. 
Prior art dishwashers have several disadvantages. First, when turning on 
the dishwasher, the operator may not know how soiled the dishes are 
without opening up the dishwasher and inspecting the dishes. Even then, 
visual inspection may not give a good indication of how dirty they are. 
Some dishes may be dirtier than others, making the user think that the 
entire load is either dirtier or cleaner than it really is. Also, there is 
no way for the user to be aware of other factors that affect the selection 
of the most effective and efficient washing cycle. Such factors include 
the amount of soil in the water, the presence of detergent in the water 
after the wash cycle starts, the water temperature, and other factors such 
as "starving" which is discussed below. In addition, the user may not know 
or remember how long the dishes have been in the dishwasher. The longer 
the dishes are in the dishwasher, the harder it is to clean the food off 
since the food will be dried on the dishes. 
Another disadvantage of prior art dishwashers is the degree of complication 
in operating the dishwasher. When turning on the dishwasher, the user must 
choose between a number of settings without necessarily knowing which is 
the best setting. Users not familiar with the dishwasher may not know 
which setting is the most effective for any set of conditions. 
In recent years, manufacturers have been able to make "smart" appliances 
which have the capability of automatically selecting cycles which were 
previously selected manually. In a "smart" appliance, the user need only 
activate a small number of buttons under normal operation. However, even 
with "smart" appliances, the effectiveness of the appliance is limited to 
the method used to select cycles. To be effective, an automatic appliance 
should select cycles based on all relevant operating conditions. In 
addition, with "smart" dishwashers, if the user is unsatisfied with the 
performance of the dishwasher, there is no way to improve the performance 
without manually selecting the wash cycles which defeats the purpose of 
having a "smart" dishwasher. 
OBJECTS OF THE INVENTION 
A general object of the present invention is the provision of a cycle 
selection method for an intelligent appliance. 
A further object of the present invention is the provision of a cycle 
selection method for an intelligent appliance which selects the most 
appropriate washing cycle for a given set of conditions. 
A further object of the present invention is the provision of a cycle 
selection method that selects a washing cycle based on the water 
turbidity, conductivity, temperature and wash arm speed. 
A further object of the present invention is the provision of a cycle 
selection method which selects a washing cycle based on the number of 
times the appliance is opened between cycles and the amount of time 
elapsed between cycles. 
A further object of the present invention is the provision of a cycle 
selection method which selects a cycle depending on the average of the 
previously selected cycles. 
A further object of the present invention is the provision of a cycle 
selection method which allows the user to adjust the cycle selection 
algorithm to choose a higher level washing cycle if the user is 
unsatisfied with the automatically selected cycles. 
A further object of the present invention is the provision of a cycle 
selection method for an intelligent appliance that selects a default cycle 
when a failure in the cycle selection system is detected. 
These as well as other objects of the present invention will become 
apparent from the following specification and claims. 
SUMMARY OF THE INVENTION 
The cycle selection method of the present invention is used to 
automatically select a washing cycle for an appliance based on various 
factors. The first factor is a combination of four operating conditions 
including water turbidity, conductivity, temperature, and wash arm speed. 
The second factor is the average of the previously selected cycles. The 
third factor is the number of times the appliance door has been opened 
since the last cycle. The fourth factor is the amount of time since the 
last wash cycle. The cycle selection method also allows the user to enter 
a value which causes the appliance to select a higher level wash cycle 
from a number of progressively higher level wash cycles. If the appliance 
controller determines that one of the sensors has failed or the 
communications routine has failed, the average of the previously selected 
cycles is selected as the wash cycle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention will be described as it applies to its preferred 
embodiment. It is not intended that the present invention be limited to 
the described embodiment. It is intended that the invention cover all 
alternatives, modifications, and equivalences which may be included within 
the spirit and scope of the invention. 
The preferred embodiment of the present invention relates to a "smart" 
dishwasher 10 as shown in FIG. 1 having a control panel 11 with a button 
11a which is used to select an automatic washing mode. If the user of the 
dishwasher 10 selects the automatic mode the dishwasher controls the 
washing and drying of the dishes by selecting the most appropriate washing 
cycle depending on the various operating conditions. 
FIG. 2 shows a block diagram of an intelligent dishwasher 10 using the 
present invention. FIG. 2 includes a wash process sensor block 12, a 
microprocessor based controller block 14, and an output block 16. 
Generally, the controller 14 receives inputs from the wash process sensor 
block 12, the rinse aid sensor 18, the door sensor 20, the current sensor 
22, and the control panel switches 24. The controller 14 uses these inputs 
to control a transistor driver 26 which in turn drives the various 
components and functions of the dishwasher as shown in the output block 
16. 
The controller 14 selects the appropriate wash cycle using a logic 
algorithm which is stored in its memory. The microprocessor used in the 
preferred embodiment has a part number MC 68HC05C9 and is available from 
Motorola. FIG. 3 shows a block diagram of the controller's cycle selection 
algorithm. The controller 14 selects a wash cycle depending on the 
combination of five variables discussed in detail below. The first 
variable is a fuzzy logic output 28 which is a function of the measured 
turbidity 30, conductivity 32, wash arm RPM 34, and water temperature 36. 
The second variable is a user adjustable variable 38 which is constant 
until the user adjusts it to suit his or her needs. The third variable is 
the average cycle variable 40 which is simply the average of the 
previously selected cycles. The fourth variable is the door openings 
variable 42 which is determined by the number of times the dishwasher door 
43 (FIG. 1) is opened between cycles. The last variable is the time 
between cycles variable 44 which depends on the amount of time elapsed 
between dishwashing cycles. During the initial wash of the dishwasher 10, 
the microprocessor based controller 14 uses the cycle selection algorithm 
shown in FIG. 3 to select the wash cycle. 
The fuzzy logic output variable 28 is the main portion of the cycle 
selection algorithm. The inputs to the fuzzy logic output variable include 
turbidity 30, conductivity 32, wash arm RPM 34, and water temperature 36. 
The sensors that provide the controller 14 with these inputs are 
preferably confined together in a sensor cluster to provide a sensor 
cluster that senses turbidity, temperature, conductivity, and the wash arm 
speed. The sensors are attached to a substrate and encapsulated by two 
plastic housings with a light transmissive and fluid impermeable material. 
The sensors are, in the embodiment, preferably located in the dishwasher 
pump housing (not shown). The sensor cluster has a part number APMS-01M 
and is available through Honeywell. The turbidity sensor measures the soil 
content in the water which is an indication of the amount of soil on the 
dishes. The temperature sensor is a thermistor. The conductivity sensor is 
a sensor that will measure the degree of conductivity within the washing 
fluids. Dishwasher detergents are an example of a conductive substance 
when dissolved in water. By using the conductivity sensor, the presence of 
detergent may be determined. The wash arm RPM sensor is used to measure 
the rate that the lower wash arm is rotating during a wash cycle. If the 
rate decreases over a wash cycle, it is an indication of the amount of 
soil present in the dishwasher. A decrease in wash arm rate may also be an 
indication of foaming or starving of the pump or of a blocked wash arm. 
The water temperature sensor simply gives the temperature of the water. 
The fuzzy logic output generates a number based on the four inputs which 
represents how soiled the dishes actually are. 
The user adjustable variable 38 allows the user to adjust the cycle that 
the dishwasher 10 would choose by inputting a key sequence on the control 
panel which will increase controller selected cycle by one to four cycle 
levels. The automatic dishwasher cycle selection algorithm will normally 
select a cycle from a number of progressively higher level washing cycles 
corresponding to no soil, lite soil, lite soil plus, normal soil and heavy 
soil. These cycles are progressively higher in level since they add water, 
wash periods and can add heat to increase the water temperature. The user 
adjustable variable allows the user to bump the selection up to the next 
higher cycle if the user is unsatisfied with the washability or 
performance of the dishwasher 10 and it is perceived that the controller 
14 is not selecting the proper cycle by itself for satisfactorily cleaning 
dishes. FIG. 4 is a flow chart showing how the user adjustable variable 38 
works. In the example shown, the user adjustable variable is initially at 
zero which results in no increase of the cycle level selected. If the 
dishwasher chooses the lite plus cycle and the user selects an adjustable 
variable of one, the cycle level is increased to the next highest cycle or 
the normal soil cycle. If the user selects two as the user adjustable 
variable, the selected cycle is increased two cycle levels to the heavy 
soil cycle. If the user selects any adjustable variable other than zero 
through three, the maximum cycle is selected. The user adjustable variable 
38 is not intended to be a normal operation of the user. Once the user 
adjustable variable 38 is selected, it will remain at the selected value 
until changed again by the user. For each increased cycle selection, the 
user adjustable variable increases the total of the cycle selection 
equation of FIG. 3 by 20 points since there are 20 points between each 
cycle. Of course, any weighting system could be used with the present 
invention. Also, the user adjustable variable 38 could be separate from 
the cycle selection algorithm. 
The third variable in the cycle selection algorithm is the average cycle 
adjust variable 40. During the operation of the dishwasher 10, the average 
cycle chosen by the dishwasher 10 is kept. This average cycle is used to 
increase the cycle selection of the dishwasher if necessary. This variable 
is intended to calculate the typical user habits, and will cause the 
machine to wash a little heavier if a borderline condition occurs between 
two possible cycle selections. In the preferred embodiment, the average 
cycle adjust variable 40 works as follows. If the average cycle is a heavy 
cycle, two points are added to the cycle selection equation. If a normal 
cycle is the average selected cycle, one point is added to the cycle 
selection equation. 
Thirty points are added to the cycle selection equation if "starving" 
occurs. "Starving" can occur when there is a lot of material in the water 
which may cause the dishwasher pump to "starve" or not circulate the water 
properly. This reduces the effectiveness of the dishwasher. 
The fourth variable in the cycle selection algorithm is the door openings 
adjust variable 42. If the dishwasher door 43 is opened more than fifteen 
times between washes, one point is added to the cycle selection algorithm. 
This variable is designed to account for the dryness of food soil on the 
dishes. For example, if the door 43 has been opened frequently, it can be 
assumed that the dishes will have varying degrees of dryness. This 
indicates that the controller 14 may need to choose a slightly heavier 
cycle if a borderline condition occurs. 
The fifth variable in the cycle selection algorithm is the time between 
cycles variable 44. The dishwasher controller 14 keeps track of the amount 
of time between wash cycles. The time between cycles variable 44 is 
intended to capture the potential dryness of the food soil on dishes in 
the dishwasher 10. The longer that food soil has been on the dishes, the 
harder it is to remove. Therefore, the longer the dishwasher 10 is not 
run, the more points will be added to the cycle selection equation. In the 
preferred embodiment, if the time between wash cycles is greater than 12 
hours, one point is added to the cycle selection equation. If the time 
between wash cycles is greater than 24 hours, two points are added to the 
cycle selection equation. It is readily apparent that the intent of the 
instant invention can also be met by utilizing different values for the 
variables in the equation of FIG. 3. 
The dishwasher controller 14 is also capable of choosing a proper default 
wash cycle if one of the following occurs: a failed turbidity sensor is 
detected, a communications failure between the control board and the wash 
process sensor 12 is detected, or a failed conductivity sensor is 
detected. The dishwasher keeps an average of the selected cycles. The 
average cycle is one factor in the cycle selection algorithm as discussed 
above. The average cycle is also used by the controller 14 as a default 
cycle if any of the above defaults occur. FIG. 5 is a flow chart showing 
the error condition cycle decision that the dishwasher 10 uses. When the 
time comes to make a cycle decision, the dishwasher controller 14 uses 
diagnostic routines to determine if there is an error with the turbidity 
sensor, conductivity sensor, or the communication routine. If no errors 
are detected, the controller 14 chooses a wash cycle using the normal 
cycle selection parameters. If an error is detected in either of the three 
areas, the average cycle is chosen as the selected cycle. FIG. 6 is a flow 
chart showing the turbidity error checking sequence which is used by the 
controller 14 to detect a turbidity sensor error. This sequence is checked 
every five seconds while a cycle is running. FIG. 7 is a flow chart 
showing the communications error detection function. FIG. 8 is a flow 
chart showing the conductivity error function. 
The present invention operates as follows. The user presses a single wash 
button 11a to start the dishwasher 10. The dishwasher 10 begins the 
initial wash cycle and then makes a selection as to the most appropriate 
washing cycle. The dishwasher controller 14 uses a cycle selection 
algorithm to determine the most appropriate cycle. The algorithm uses a 
fuzzy logic output (which depends on the water turbidity, conductivity and 
temperature as well as the wash arm speed), the average of the previously 
selected cycles, the number of times the dishwasher door 43 has been 
opened since the previous cycle, the amount of time since the last wash 
cycle, and user input. Using this algorithm, the cycle selected should be 
the most appropriate cycle for any given set of conditions. If at some 
point the user is unhappy with the performance of the dishwasher, a series 
of key strokes can bump-up the selected cycle to the next higher cycle. 
Thereafter, a cycle higher than the automatically selected cycle will be 
chosen. If the dishwasher controller 14 detects an error with the 
turbidity sensor, conductivity sensor, or the communications routine, the 
controller 14 will select the average selected cycle as a default. 
The preferred embodiment of the present invention has been set forth in the 
drawings and specification, and although specific terms are employed, 
these are used in a generic or descriptive sense only and are not used for 
purposes of limitation. Changes in the form and proportion of parts as 
well as in the substitution of equivalents are contemplated as 
circumstances may suggest or render expedient without departing from the 
spirit and scope of the invention as further defined in the following 
claims.