Water filter abstract
A low cost method and apparatus for indicating when to replace
a water filter in a water and ice delivery system for a refrigerator.
The invention uses a low cost microprocessor and senses the operational
condition of an ice maker water valve, a water dispenser valve to
monitor and track water usage. The microprocessor has a built-in
memory to retain water usage and other data during a power outage,
The invention also senses the status of a door switch to permit
user input of a reset message indicating that the filter has been
changed as well as an input indicating a different type of filter
has been installed. The microprocessor controls a tri-color light
emitting diode to display the status of the filter as "good",
"order" or "change" which is determined based
on the selection of the type of filter system, the amount of time
since the last filter change, and the amount of water usage since
the last filter change.
Water filter claims
What is claimed is:
1. In a water delivery system for delivering water to a water delivery
station, said water delivery system having a replaceable filter
and at least one water valve selectively operable to allow water
passed through said replaceable filter to flow to said water delivery
station, a water filter monitor and indicator assembly for indicating
the status of said filter comprising:
a sensor detecting the operational status of said valve as being
open or closed and providing an open.backslash.closed output indicative
of the operational status of said valve;
a clock providing a time output indicative of the current time;
a door switch responsive to the opening and closing of a door and
for providing a reset output;
a data processor comprising:
first, second and third data storage locations for data corresponding
respectively to the amount of filter usage, the age of the filter,
and the status of the filter;
a plurality of criteria, corresponding to pre-selected operational
life standards for said replaceable filter; and
a plurality of inputs respectively adapted to receive said reset
output, said open.backslash.closed output and said time output;
said data processor further comprising programming adapted to:
process said reset output to reset data in said first and second
data storage locations to zero;
process said open.backslash.closed output to calculate and store
in said first data storage location the amount of time that said
open.backslash.closed output has indicated that said valve is open
since the last time data in said first data storage location has
been reset to zero;
process said time output to calculate and store in said second
data storage location the amount of time that has passed since data
in said second data storage location has been reset to zero;
compare data in said first and second data storage locations with
said plurality of criteria and store in said third data storage
location data indicative of one of a first, second or third filter
status corresponding, respectively to a good filter, a filter which
is near a condition of needing replacement, and a filter which needs
to be replaced based on said criteria;
generate a filter status output indicative of one of said first,
second or third filter statuses; and
an indicator adapted to receive said filter status output and to
provide an indication of the filter status to the user.
2. In the water delivery system of claim 1 the improvement wherein
said data processor comprises a microprocessor and a memory device,
said memory device providing for continuing storage of data in said
first, second and third data storage locations in the event of a
power outage.
3. In the water delivery system of claim 1 the improvement wherein
said plurality of criteria comprises:
a first pre-selected number representing a maximum operational
time period for usage of said replaceable filter;
a second pre-selected number less than said first pre-selected
number representing an operational time period after which a user
should consider obtaining a replacement for said replaceable filter;
a third pre-selected number representing a maximum total time period
for installation of said replaceable filter;
a fourth pre-selected number less than said third pre-selected
number representing an installed time period after which a user
should consider obtaining a replacement for said replaceable filter;
and further wherein said data processor stores in said third data
storage location:
an indication that said filter needs to be replaced if said first
data storage location has a number exceeding said first pre-selected
number or said second data storage location has number exceeding
said second pre-selected number;
an indication that said filter is good if said first data storage
location has a number below said third pre-selected number and said
second data storage location has number below said fourth pre-selected
number; and
an indication that said filter will soon be in need of replacement
otherwise.
4. In the water delivery system of claim 1 the improvement wherein
said indicator provides a visual indication of filter status.
5. In the water delivery system of claim 4 the improvement wherein
said indicator comprises:
a tri-color light emitting diode adapted to emit a first, second
and third color; and
a control circuit comprising:
an input adapted to receive said filter status output; and
an output for illuminating said light emitting diode in first second
and third colors in response, respectively, to said filter status
output indicating, respectively, said first, second and third filter
status.
6. In the water delivery system of claim 5 the improvement wherein
said first, second and third colors comprise green, yellow and red
respectively.
7. In the water delivery system of claim 1 the improvement wherein:
said plurality of criteria comprises at least a first and a second
set of criteria corresponding respectively to pre-selected operational
life standards for a first and a second type of said replaceable
filter; and
said data processor further comprises a fourth data storage location
for storing data indicative of the whether said filter is of said
first or second type; and
said programming is adapted to read the type of filter and select
the appropriate criteria for said replaceable filter.
8. In the water delivery system of claim 7 the improvement wherein
each of first and second set of criteria comprises:
a first pre-selected number representing a maximum operational
time period for usage of said replaceable filter;
a second pre-selected number less than said first pre-selected
number representing an operational time period after which a user
should consider obtaining a replacement for said replaceable filter;
a third pre-selected number representing a maximum total time period
for installation of said replaceable filter;
a fourth pre-selected number less than said third pre-selected
number representing an installed time period after which a user
should consider obtaining a replacement for said replaceable filter;
and further wherein said data processor reads the type of filter
in said fourth data storage location to select the corresponding
first, second, third and fourth pre-selected numbers and then stores
in said third data storage location:
an indication that said filter needs to be replaced if said first
data storage location has a number exceeding said first pre-selected
number or said second data storage location has number exceeding
said second pre-selected number;
an indication that said filter is good if said first data storage
location has a number below said third pre-selected number and said
second data storage location has number below said fourth pre-selected
number; and
an indication that said filter will soon be in need of replacement
otherwise.
9. In the water delivery system of claim 1 wherein there are at
least two of said valves, the improvement wherein:
said water filter monitor and indicator assembly further comprises
at least two of said sensors each respectively detecting the operational
status of one of said valves as being open or closed and providing
an open.backslash.closed output indicative of the operational status
of said valve; and
said programming is adapted to store in said first data storage
location the total open time of all of said valves.
10. A water filter monitor and indicator assembly for use in a
refrigerator having a cabinet with a fresh food compartment, a fresh
food door hingedly mounted to said cabinet to open and close said
fresh food compartment, a fresh food door switch selectively activated
by the closing of said fresh food door, an ice maker and an ice
and water delivery assembly mounted to said cabinet, first and second
water supply lines for delivering water to said ice maker and to
said ice and water delivery system, first and second valves respectively
disposed along said first and second water supply lines and operable
to allow water to pass through said supply lines, a main supply
line delivering water to both said first and second supply lines
and a replaceable filter disposed along said main supply line; said
water filter monitor and indicator assembly comprising:
a first and a second sensor detecting the operational status of
said first and said second valves, respectively, as being open or
closed and providing a first and second open.backslash.closed output,
respectively indicative of the operational status of said valve;
a third sensor detecting the status of said door switch as being
depressed by said fresh food door or being relaxed and providing
a door status output indicative of the open or closed status of
said fresh food door;
a clock providing a time output indicative of the current time;
a data processor comprising:
first, second and third data storage locations for data corresponding
respectively to the amount of filter usage, the age of the filter,
and the status of the filter;
a plurality of criteria, corresponding to pre-selected operational
life standards for said replaceable filter; and
a plurality of inputs respectively adapted to receive said door
status output, said first and second open.backslash.closed output
and said time output;
said data processor further comprising programming adapted to:
process said door status output to reset said first and second
data storage locations to zero when said programming detects a pre-selected
sequence of open and close inputs have been received from said door
switch sensor indicative of a intentional manual input of a reset
command;
process said first and second open.backslash.closed outputs to
calculate and store in said first data storage location the total
amount of time that either of said open.backslash.closed outputs
has indicated that a valve is open since the last time data in said
first data storage location has been reset to zero;
process said time output to calculate and store in said second
data storage location the amount of time that has passed since data
in said second data storage location has been reset to zero;
compare data in said first and second data storage locations with
said plurality of criteria and store in said third data storage
location data indicative of one of a first, second or third filter
status corresponding, respectively to a good filter, a filter which
is near a condition of needing replacement, and a filter which needs
to be replaced based on said criteria;
generate a filter status output indicative of one of said first,
second or third filter statuses; and
an indicator adapted to receive said filter status output and to
provide an indication of the filter status to the user.
11. The water filter monitor and indicator assembly of claim 10
wherein said pre-selected sequence of open and close inputs for
indicating an intentional input of a reset command consists of a
predetermined quantity of open and closed outputs within a predetermined
time period, such time period being selected to be sufficiently
short as to reduce significantly the possibility that such signal
would be inadvertently generated during normal operation of the
fresh food door.
12. The water filter monitor and indicator assembly of claim 10
wherein said plurality of criteria corresponding to pre-selected
operational life standards for said replaceable filter comprise
pre-selected capacity and age criteria for replacement of said replaceable
filter and a pre-selected percentage of said capacity and age criteria
for warning the user to replace said replaceable filter.
13. The water filter monitor and indicator assembly of claim 12
wherein said pre-selected percentage is 90%.
14. The water filter monitor and indicator assembly of claim 10
wherein said plurality of criteria comprises:
a first pre-selected number representing a maximum operational
time period for usage of said replaceable filter;
a second pre-selected number less than said first pre-selected
number representing an operational time period after which a user
should consider obtaining a replacement for said replaceable filter;
a third pre-selected number representing a maximum total time period
for installation of said replaceable filter;
a fourth pre-selected number less than said third pre-selected
number representing an installed time period after which a user
should consider obtaining a replacement for said replaceable filter;
and further wherein said data processor stores in said third data
storage location:
an indication that said filter needs to be replaced if said first
data storage location has a number exceeding said first pre-selected
number or said second data storage location has number exceeding
said second pre-selected number;
an indication that said filter is good if said first data storage
location has a number below said third pre-selected number and said
second data storage location has number below said fourth pre-selected
number; and
an indication that said filter will soon be in need of replacement
otherwise.
15. The water filter monitor and indicator assembly of claim 10
wherein said indicator comprises:
a tri-color light emitting diode adapted to emit a first, second
and third color; and
a control circuit comprising:
an input adapted to receive said filter status output; and
an output for illuminating said light emitting diode in first,
second and third colors in response, respectively, to said filter
status output indicating, respectively, said first, second and third
filter status.
16. The water filter monitor and indicator assembly of claim 10
wherein:
said plurality of criteria comprises at least a first and a second
set of criteria corresponding respectively to pre-selected operational
life standards for a first and a second type of said replaceable
filter; and
said data processor further comprises a fourth data storage location
for storing data indicative of whether said filter is of said first
or second type; and
said programming is adapted to read the type of filter and select
the appropriate criteria for said replaceable filter.
17. The water filter monitor and indicator assembly of claim 16
wherein each of first and second set of criteria comprises:
a first pre-selected number representing a maximum operational
time period for usage of said replaceable filter;
a second pre-selected number less than said first pre-selected
number representing an operational time period after which a user
should consider obtaining a replacement for said replaceable filter;
a third pre-selected number representing a maximum total time period
for installation of said replaceable filter;
a fourth pre-selected number less than said third pre-selected
number representing an installed time period after which a user
should consider obtaining a replacement for said replaceable filter;
and further wherein said data processor reads the type of filter
in said fourth data storage location to select the corresponding
first second third and fourth pre-selected numbers and then stores
in said third data storage location:
an indication that said filter needs to be replaced if said first
data storage location has a number exceeding said first pre-selected
number or said second data storage location has number exceeding
said second pre-selected number;
an indication that said filter is good if said first data storage
location has a number below said third pre-selected number and said
second data storage location has number below said fourth pre-selected
number; and
an indication that said filter will soon be in need of replacement
otherwise.
Water filter description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a water filtration system for a refrigerator
and more particularly to an indicator for notifying a user when
to change the filter.
2. Description of the Related Art
Many refrigerators, and especially those using a side-by-side configuration
wherein the fresh food compartment is located to one side of the
frozen food compartment, include integrated ice and water delivery
systems. Typically, such systems deliver water and ice through the
door of the frozen food compartment to an ice and water station
recessed in the door.
Increasingly such systems incorporate a filtration system with
a replaceable filter element or cartridge so as to improve the quality
of the ice and water delivered to the user of the refrigerator.
Examples of such systems can be seen in U.S. Pat. No. 5907958
issued Jun. 1 1999 to Coates, et al. and entitled "Refrigerator
water filter"; U.S. Pat. No. 5813245 issued Sep. 29 1998
to Coates, et al. and entitled "Pressure relief circuit for
refrigerator contained water filter"; U.S. Pat. No. 5715699
issued Feb. 10 1998 to Coates, et al. and entitled "Refrigerator
water filter"; U.S. Pat. No. 5707518 issued Jan. 13 1998
to Coates, et al. and entitled "Refrigerator water filter";
U.S. Pat. No. 5135645 issued Aug. 4 1992 to Sklenak, et al. and
entitled "Refrigerator water filter"; and U.S. Pat. No.
3982406 issued Sep. 28 1976 to Hanson, et al. and entitled "Refrigerator
water storage and dispensing system with water filter".
Since the filters must be periodically replaced to maintain the
quality of the water, various methods and apparatus could be used
to notify the user of the need to change the filter. However, such
many potential approaches would be costly, complex and inflexible
as to substitution of different types of filters having different
useful lives. Furthermore, in an effort to such reduce cost, many
such approaches fail to give the user advance warning that the filter
will soon need to be replaced. Additionally, the controls might
be used on more than one model of refrigerator in conjunction with
more than one type of filtration media.
What is needed, therefore, is a filter monitoring and indicating
system that is flexible enough to permit its use with different
types of filters. It would be most beneficial if the system doesn't
add the cost of requiring an additional switch or sensor for detecting
the type of filter being used but instead relies on existing components,
where possible.
What is further needed is an inexpensive filter monitoring and
indicating system that not only informs the user that a filter needs
to be replaced, but provides earlier warning that the filter will
need to be replaced soon and therefore a new filter needs to purchased.
SUMMARY OF THE INVENTION
The present invention is directed to a low cost method and apparatus
for monitoring the operation of a water and ice delivery system
for a refrigerator and indicating when to replace a water filter
used in the water and ice delivery system.
The water filter monitoring and indicating method and apparatus
of the present invention relies on components existing in many conventional
water and ice delivery systems and refrigerators to reduce complexity
and number of components. It senses the operational condition of
the fresh food compartment door and the valves regulating the water
flow into the ice maker and the water dispenser of the refrigerator.
The method and apparatus monitors and tracks the duration of valve
openings to estimate water consumption since the filter has been
changed. Furthermore, it tracks the amount of time that has passed
since the last time the filter has been changed. The method and
apparatus further tracks user inputs to the fresh food compartment
door switch to determine when a filter has been replaced.
The water filter monitoring and indicating method and apparatus
of the present invention determines when the filter needs to be
changed by comparing the water usage and filter age data with a
first set of pre-selected standards for the type of filter being
used and further determines when a new filter should be ordered
by comparing the water usage and filter age data with a second set
of pre-selected standards for the type of filter being used, the
second set of pre-selected standards being more stringent than the
first set. The method and apparatus then uses a tri-color light
emitting diode to display one color when the filter should be replaced,
a second color when a filter should be ordered and a third when
the filter is good.
In the preferred embodiment of the present invention, the water
filter monitoring and indicating system uses a low cost microprocessor
to compare the water usage and filter age data with the first and
second sets of pre-selected standards, to generate and track a conclusion
of a status of "good", "order" (or alternatively,
"warn") or "change" (or alternatively, "used")
for the filter based on such comparison, and to illuminate the light
emitting diode in pre-selected color corresponding to that conclusion
of status.
The microprocessor of the water filter monitoring and indicating
system of the present invention preferably includes a built-in memory
to retain water usage and other data during a power outage.
The light emitting diode of the water filter monitoring and indicating
system preferably is illuminated green for a filter status of "good",
yellow for a filter status of "order" or "warn"
and red for a filter status of "change" or "used".
In the preferred embodiment, the indicator warns the user that
the filter will soon be past its rated capacity and therefore that
a new filter should be ordered when the filter has reached 90% of
its rated age or rated water capacity. This increases the likelihood
that a user will have a filter available when one is needed and
increased the likelihood that the filter will be replaced in a timely
manner. Typical settings for filters may be 400 gallons or 200 gallons
capacity and warn at 360 gallons or 180 gallons, respectively.
In the preferred embodiment, the microprocessor further tracks
the time that the filter has been installed and compares that with
the rated life of the filter, which could be typically between 6
months and 12 months. The user will be warned to replace the filter
when it has been installed in the refrigerator for more than 90%
of its maximum rated installation life or age. The indicator will
therefore illuminate green for a status of "good" if the
filter is newer than 90% of its maximum rated age and has been used
to deliver less than 90% of its rated capacity and will illuminate
red for a status of change if it has exceeded 100% of either limit.
Otherwise, it will illuminate yellow, for warn, indicating that
it is between 90% and 100% for either age or capacity and will shortly
need to be replaced.
The water filter monitoring and indicating system preferably further
tracks user inputs to the fresh food compartment door switch to
determine what type of filter is being used and utilizes a different
first and second set of pre-selected standards for each type of
filter selectable by the user. This can be accomplished within the
microprocessor by changing the age and or capacity limits or by
altering the speed of the internal counter.
The microprocessor is provided with programing to detect a first
predetermined rapid sequence of depressions of the door switch as
a request by the user to reset the age and usage counters to zero
because the filter has been changed. The sequence of pulses is selected
to be numerous and rapid enough to be unlikely to be accidentally
sent during normal door openings and closings. The microprocessor
further interprets a second predetermined sequence of depressions
of the door switch as a sign that a different type of filter is
being used
The light emitting diode of the water filter monitoring and indicating
system is preferably located within the fresh food compartment of
the refrigerator near the fresh food compartment door switch of
the refrigerator to ease use of the indicator and to function aesthetically
with the door switch in a control console that can also include
the fresh food and frozen food temperature controls. The control
console is preferably located on the upper front face of the fresh
food compartment so as to minimize access by children.
It is therefore an object of the present invention to provide the
consumer with a reliable measure of the filter cartridge end of
life condition.
It is a further object of the present invention to provide an inexpensive
filter monitoring and indicating system that informs the user that
the filter needs to be replaced, by illuminating red and further
provides early warning that the filter will need to be replaced
soon and therefore a new filter needs to purchased by illuminating
yellow.
It is another object of the present invention to provide a filter
monitoring and indicating system that is flexible enough to permit
its use with different types of filters yet doesn't add the cost
of requiring an additional switch or sensor for detecting the type
of filter being used by utilizing manual user input to the existing
fresh food compartment door switch at a rate which would be unlikely
to occur in normal door openings and closings.
These and other advantages of the present invention will become
apparent to those skilled in the art when the following detailed
description of the preferred embodiment is read in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front perspective view of a refrigerator apparatus
having a water filtration and filter control and indicator system
embodying the present invention;
FIG. 2 is a schematic diagram of the ice and water assembly of
the refrigerator apparatus of FIG. 1;
FIG. 3 is a fragmentary enlarged front view of the refrigerator
control console of the refrigerator of FIG. 1;
FIG. 4 is a schematic electrical diagram illustrating the electrical
circuitry of the filter control and indicator system of FIG. 1;
FIG. 4b is a table indicating specifications of preferred components
of the filter control and indicator system of FIG. 4;
FIG. 5 is a flow chart illustrating the programming and logic of
the filter control and indicator system of FIGS. 1 and 4 and more
particularly illustrates the power-up and main subroutines of the
filter control and indicator system;
FIG. 6 is a flow chart illustrating the filter status subroutine
of the main subroutine of FIG. 5 comprising FIG. 6A and FIG. 6B;
FIG. 7 is a flow chart illustrating the indicator subroutine of
the main subroutine of FIG. 5 including the indicator subroutine
and the diagnostics subroutine; and
FIG. 8 is a flow chart illustrating the reset subroutine of the
main subroutine of FIG. 5;
DESCRIPTION OF THE PREFERRED EMBODIMENT
The Refrigerator
In the illustrative embodiment of the invention as shown in FIG.
1 a refrigerator 10 comprising a side-by-side fresh food/freezer
configuration, is provided having a cabinet 12 forming fresh food
compartment 14 and freezer compartment 16.
The fresh food compartment 14 is provided with an access opening
18 and a fresh food door 20 hingedly mounted to the cabinet 12 for
selectively closing the access opening 18. The access opening 18
has a back wall 18a, side walls 18b and 18c, top wall 18d, and a
bottom wall 18e. The refrigerator 10 also has a partial front wall
22 disposed around the perimeter of the access opening 18 parallel
to and selectively engageable with the fresh food door 20 for sealing
the access opening 18.
The fresh food compartment 14 is further provided with a light
24 which is connected in series with a light switch 26. The light
switch 26 is a reciprocable switch actuated to selectively connect
the light 24 with a source of electrical power, not shown, when
the door 20 is in an open position and to disconnect the light 24
from the source of electrical power when the fresh food door 20
is in the closed position. In the preferred embodiment, the light
switch is located in portion of the partial front wall 22 above
the top wall 18d of the access opening.
Similarly, the freezer compartment 16 is provided with an access
opening 28 and a freezer door 30 hingedly mounted to the cabinet
12 for selectively closing the access opening 28. The access opening
28 has a back wall 28a, side walls 28b and 28c, top wall 28d, and
a bottom wall 28e. The refrigerator 10 also has a partial front
wall 32 disposed around the perimeter of the access opening 28 parallel
to and selectively engageable with the freezer door 30 for sealing
the access opening 28 . The freezer compartment 14 is farther provided
with a rocker-type light switch 34 which is connected in series
with a light 36 functionally similar to the light 24 and light switch
26 in the fresh food compartment 14.
As is farther well known in the art, the refrigerator 10 is provided
with a water and ice supply system 40 shown schematically in FIG.
2 for delivering water from an external source 42 through a filter
44 to an ice and water delivery system 46.
The filter 44 may be mounted to the refrigerator below the bottom
wall 28e of the access opening 28 and accessed for servicing by
selective removal through an opening through the lowermost portion
of the partial front wall 32 as shown in FIG. 1. The ice and water
delivery system 46 includes an ice making assembly 48 mounted within
the freezer compartment 16 and an ice and water dispensing system
46 mounted in the freezer door 30.
The ice making assembly 48 is mounted to the inside surface of
the back wall 28a of the freezer compartment 16. The ice and water
dispensing system 46 is provided below the ice making assembly 48
for receiving ice pieces therefrom as well as for receiving cool
water from a water supply system 40. As shown in FIG. 2 the water
and ice supply system 40 includes electrically operable water valves
52 and 54 for supplying water, respectively, to the ice making assembly
48 and the ice and water dispensing system 46.
The ice and water dispensing system 46 includes an ice storage
receptacle or bin not shown. When operated, the ice and water dispensing
system 46 transfers ice pieces from the ice storage receptacle or
bin through the freezer door 30 whereby ice pieces may be dispensed
through a conventional, forwardly exposed ice dispenser station
or external ice service area not shown.
In the preferred embodiment of the present invention, a refrigerator
control console 60 is defined on an upper portion of the partial
front wall 22 of the fresh food compartment 16 in the vicinity of
the light switch 26. The refrigerator control console 60 which
is shown integral with the front wall 22 includes a fresh food
compartment temperature control switch 62 a freezer compartment
temperature control switch 64 the light switch 26. In the vicinity
of the light switch 26 the refrigerator control console also includes
a filtration system status indicator 66 described later in detail.
The refrigerator control console 60 further incorporates a consumer
label 67 surrounding the switch 26 and the indicator 66 on which
is printed the following written matter describing the operation
of the filter 44 and the meaning of the status indicator 66:
"EZ-CHANGE SIGNAL FILTER INDICATOR RESET Green = Good Filter
Push the light switch Yellow = Order Filter 5 times in 10 seconds
to reset Red = Change Filter filter indicator to green."
Components of The Water Filter Status Monitoring and Indicating
System
Referring now to the FIG. 4 the Refrigerator 10 includes a water
filter status monitoring and indicating system 70. The water filter
status monitoring and indicating system 70 includes a power supply
72 comprising resistor 74 capacitors 76 78 and 80 and diodes 82
84 and 86 in a conventional capacitive drop design with capacitor
76 as the charge pump device, diode 82 as the rectifier. Diode 84
provides noise suppression and functions as a clamping diode. Diode
86 is a zener diode used as a simple voltage regulator. Capacitor
80 functions as the reservoir capacitor and capacitor 78 provides
high frequency bypass. Resistor 74 is critical to line surge performance
of the overall circuit since it absorbs most of the pulse energy.
The water filter status monitoring and indicating system 70 has
an input connector 90 with three identical discrete digital inputs
94 96 and 98. Input 94 monitors the operational status of light
switch 26. Input 96 monitors the operational status of the electrical
input of water valve 54 associated with the water dispenser of the
ice and water dispensing system 46. Input 98 monitors the operational
status of the electrical input of water valve 52 associated with
the ice making apparatus 48. These inputs are designed for 120V
(RMS) signals directly from the monitored loads. Each of these inputs
92 94 and 96 has an identical input resistive divider network respectively
comprised of pairs of resistors 114a, 114b, 116a, 116b, 118a and
118b. Each resistor pair, 114 116 and 118 can also be viewed as
a series device to limit current into the microprocessor input pins
107 108 and 109 respectively, to the microprocessor device 140
described later, and a shunt device to provide input pull-down to
a known state when the associated load is not activated.
The input connector 90 further has inputs 100 and 106 respectively
connected to the neutral and the hot lines of the AC power supplied
to the refrigerator 10. Inputs 92 102 and 104 of the input connector
90 are not used.
The water filter status monitoring and indicating system 70 also
has a power-on reset circuit 120 comprised of resistors 122 124
and 126 transistor 128 and capacitor 130. Resistors 122 and 126
set the reset threshold voltage and provide base drive for the transistor
128 and, in turn provides a pull-up voltage to master clear input
147. Resistor 124 is a passive pull-down to the master clear input
147 of the microprocessor device 140 when VDD is low which establishes
a valid logic low when VDD is below the threshold. Capacitor 130
provides filtering for high frequency noise and transients.
The water filter status monitoring and indicating system 70 further
includes the filtration system status indicator 66 which in the
preferred embodiment consists of a bi-color device 110 containing
a red LED die 132 and a green LED die 134.
The microprocessor device 140 provides all logic functionality
and memory. In addition to red and green, the color amber can be
achieved by alternating resistors 136 and 138 by providing alternating
signals from microprocessor output pins 144 and 146.
Microprocessor device 140 is preferably a Microchip PIC 12CE518
device, which contains 512 words of program ROM (implemented as
OTP EPROM) and includes a 16 by 16 EEPROM.
The specifications of the preferred components of the water filter
status monitoring and indicating system 70 are as indicated on Table
1 on FIG. 4b.
Programming Logic of The Water Filter Status Monitoring and Indicating
System
FIG. 5 through FIG. 8 illustrate the programming and logic of the
water filter status monitoring and indicating system 70 which is
programmed into the microprocessor device 140. The Logic is intended
to provide programming for alternative models, such as an A model
refrigerator a B model refrigerator or a C model refrigerator, each
having different functionality. The various models may have different
replacement criteria for the filters depending on the gallon rating
and the useful life of the filter.
Referring to FIG. 5 when the power is first supplied to the microprocessor
device 140 a Power-up Subroutine 200 is initiated. At step 202
the microprocessor device reads the stored memory. At Step 204
the microprocessor device 140 sends a signal to the indicator 66
to flash red if the refrigerator is a Model A and green if it is
a model B.
The microprocessor device 140 then enters a continuously repeated
main subroutine 206. Within each repetition of main subroutine 206
microprocessor device 140 updates its clock at step 208 and, once
every 18 hours, stores the time and water used in the non-volatile
memory at step 210. At steps 212 and 214 respectively, the amount
of water used is incremented if the ice valve 52 is open or if the
fresh water valve 54 is open. The open time for each valve 52 and
54 is weighted for the normal water flow rate associated with the
valve. At steps 216 218 and 220 respectively, the microprocessor
calls the filter status subroutine 250 the control subroutine 300
and the reset subroutine 350 after which the main subroutine 206
repeats.
Referring to FIG. 6 the filter status subroutine 250 determines
at steps 252 and 254 whether refrigerator 10 is a model A, B or
C and directs the program to one of water usage comparison subroutines
256a, 256b and 256c, respectively for the appropriate model. In
each respective water usage comparison subroutine 256a, 256b, and
256c, at respective steps 258a, 258b and 258c, the status of the
filter is designated as "good" if less than a first predetermined
time period has passed and less than a first predetermined quantity
of water has been consumed, as indicated by the information stored
in memory since the last reset. In each respective water usage comparison
subroutine 256a, 256b, and 256c, at respective steps 260a, 260b
and 260c, the status of the filter is designated as "used"
if more than a second predetermined time period of usage or more
than a second predetermined quantity of water has been consumed
since the last reset. In each respective water usage comparison
subroutine 256a, 256b, and 256c, at respective steps 262a, 262b
and 262c, the status of the filter is designated as "warn"
if the status has been set as neither "good" or "used".
Finally, at step 270 the time and water used is stored in non-volatile
memory if the status of the filter has not been changed by the water
usage comparison subroutine 256a, 256b or 256c. The status is not
restored if it hasn't changed so as to maximize the useful life
of the EEPROM non-volatile memory.
Referring to FIG. 7 the control subroutine 300 determines at step
302 if the fresh food door 20 is open by monitoring the voltage
across the fresh food light switch 26.
If the fresh food door 20 is detected as open, then indicator subroutine
310 is run. At step 312 the green LED die 134 is illuminated if
the status of the filter has been saved as "warn" or as
"good". At step 314 the red LED die 132 is illuminated
if the status of the filter has been saved as "warn" or
as "used". Thus, if the status has been saved as "warn",
both LED die are illuminated and the status indicator 66 appears
amber in color.
The alternating signal of red and green is created by step 312
always turning off the green die, off if it is on, and, after a
built-in time delay by having step 314 always turn off the red die,
if it is on.
If the fresh food door 20 is detected as closed, then diagnostic
subroutine 320 is run. At step 322 the green LED die is illuminated
if the fresh water dispenser valve 54 is open. At step 324 the
red LED die is illuminated if the water valve 52 to the ice making
apparatus 48 is open. If both valves 52 and 54 are open, both LED
die are illuminated and the status indicator 66 appears amber. The
diagnostic subroutine 320 permits detection of malfunctions of the
water valves 52 and 54 or the water filter status monitoring and
indicating system 70 by a service technician manually be depressing
the light switch 26 and selectively operating the valves 52 or 54
the service technician can isolate faults in the system.
Referring to FIG. 8 the reset subroutine 350 determines at steps
352 if the light switch 26 has been depressed 5 times in less than
ten seconds, indicating the user is sending a reset instruction
to the microprocessor device 140. The user should do this when the
filter is replaced. If a reset instruction has been detected at
step 352 then the time and water usage counters are reset to zero
at step 356 and stored at step 358. However, if the system has already
been reset, within the last 10 seconds, that is, a reset instruction
has been sent twice, then, at step 354 the microprocessor device
reads the input as an instruction that a different type of filter
is being used and changes the model setting from a model A to a
model B. Finally, at step 360 the indicator is illuminated red
or green to indicate the model setting.
The following details are offered to provide with even more particularly
details of the best mode contemplated by the inventors at the time
of filing for implementing the control described above.
Inputs/Outputs Active: Inactive: Ice Valve Input 60 Hz Input Logic
Level Low Water Valve Input 60 Hz Input Logic Level Low Light Switch
Input 60 Hz Input Logic Level Low Red LED High Logic Level Green
LED High Logic Level
The filter counter (not illustrated) is a 16 bit counter in that
is incremented as the ice and water valves are used. The counter
is incremented once every time the valve on time reaches 2.5 seconds
for the ice valve and 1.5 seconds for the water valve. These above
values are determined by the flow rates of the valves actually used
in the preferred embodiment and the resolution of the 8 bit timers
that count the on time of the valves and may vary. Valve usage is
recorded in 10 ms increments; therefor the maximum on time that
can be recorded in 8 bits is 2.55 seconds.
Each increment of the filter counter represents the passage of
0.0125 gallons of water. A filter count value of 40000 represents
500 gallons used and a filter count of 36000 represents 450 gallons
used. A filter count of 32000 represents 400 gallons used and a
filter count of 28800 represents 360 gallons used. To minimize
the code the software only checks the upper byte of this counter.
Therefore the closest HEX values give trip points of 40192 (0.times.9D00)
and 36096 (0.times.8D00) for normal mode and 32000 (0.times.7D00)
and 28672 (0.times.7000) for cyst mode. The trip points in gallons
are then 502.4 and 451.2 for normal mode and 400 and 358.4 for cyst
mode.
The Real Time Counter is a 24-bit counter that is incremented every
second. This counter is used to keep track of times up to 6 months
in length. When 6 months is reached the counter is cleared and a
flag is set to indicate that 6 months has passed. When a second
6 months has passed the timer is then frozen.
Time is kept using the internal RC oscillator. Using the preprogrammed
oscillator calibration, 6 months can be timed to within +/-1 week.
In a Model A or B control the real time counter is incremented
every 0.5 seconds. Therefore the timer resets when 3 months of actual
time has passed. The six-month flag is then a 3-month flag.
Operation of the Water Filter Status Monitoring and Indicating
System Components
The purpose of the water filter indicator is to provide the consumer
with a reliable measure of the filter cartridge end of life condition.
There are two criteria for end of life, namely a prescribed number
of gallons or a fixed period of real time. In order to monitor the
water flow, the electrical inputs to both the ice maker valve and
the dispenser valve are monitored by the WFI. Since the processor
"knows" that the valves have flow rates of 0.3 and 0.5
gallons per minute, the flow can be computed from the amount of
time which each is energized. It is in this fashion that the usage
in gallons is accumulated.
Real time is simply accumulated by a divider from the processor
clock. Since the clock used in this case is the internal RC oscillator,
it is subject to more inaccuracy than would be experienced with
a crystal controlled or 60 Hz based time keeping scheme. The Microchip
literature guarantees this tolerance to be about 7.0% over voltage
and temperature variations. Also included in the microprocessor
is an EEPROM device, which provides non-volatile retention of flow
as well as real time. In the preferred embodiment there is pre-programmed
OSCCAL (oscillator calibration) value described in Sec. 8.2.5 pg.
32 of the PIC12CE5XX Data Sheet. This tightens up the tolerance
so that we can guarantee 6 mo. +/-1 week (.about.4%).
The state of the water filter is indicated on a bi-color LED incorporating
a red and a green die in the same package. By activating both die
at a 50% duty cycle an amber color is obtained. Up to 90% life the
indicator is green, from 90% to just less than 100% it is amber,
and at end of life it shows red. User reset of the accumulated flow
and time variables is effected by activating the door switch five
times within 5 seconds.
In order to facilitate factory test as well as servicing in the
field, the LED displays usage status only when the door is open.
When the door is closed, the LED is off unless one or both of the
valve inputs is active. The LED indicates red for the ice maker
valve, green for the dispenser valve and amber if both valves are
active.
The present invention therefore provide the consumer with a reliable
measure of the filter cartridge end of life condition.
The present invention further provides an inexpensive filter monitoring
and indicating system that informs the user that filter needs to
be replaced, by illuminating red and further provides early warning
that the filter will need to be replaced soon and therefore a new
filter needs to purchased by illuminating yellow.
The present invention additionally provides a filter monitoring
and indicating system that is flexible enough to permit its use
with different types of filters yet doesn't add the cost of requiring
an additional switch or sensor for detecting the type of filter
being used by utilizing manual user input to the existing fresh
food compartment door switch at a rate which would be unlikely to
occur in normal door openings and closings.
The above constitutes a detailed description of the best mode of
the present invention as contemplated by the inventors at the time
of filing. It is further contemplated that changes and modifications
may be made from the best mode described herein within without departing
from the spirit of the present invention or the intended scope of
the claims below. |