Clothes washer filling control systems and methods

1. A circuit comprising:

a processor programmed to prevent overfilling of a cabinet with a fluid;

a pressure sensor operatively coupled to said processor; and

a backup circuit having fixed logic, said backup circuit electrically coupled to said processor to redundantly prevent overfilling the cabinet with the fluid, said backup circuit including a first comparator that compares the signal from said pressure sensor with an overfill reference signal to indicate an overfill condition and a second comparator that compares the signal from said pressure sensor to a sensor error voltage to indicate an invalidity of the signal from said pressure sensor, said backup circuit acting independently of said processor to disable a flow of fluid to the cabinet when the overfill condition is indicated, and said backup circuit acting independently of said processor to disable a flow of fluid to the cabinet when the invalidity of the signal is indicated.

2. A circuit according to claim 1 , wherein said pressure sensor is electrically coupled to said backup circuit for measuring a fluid level in the cabinet, said pressure sensor generates a signal that is proportional to the fluid level.

3. A circuit according to claim 2 , wherein said processor calculates the fluid level based on the signal from said pressure sensor.

4. A circuit according to claim 1 , wherein said backup circuit acts independently of said processor to disable a flow of fluid to the cabinet when the overfill condition is indicated to close a valve for filling said cabinet when the signal from said pressure sensor is greater than said overfill reference signal.

5. A circuit according to claim 1 , wherein said backup circuit acts independently of said processor to disable a flow of fluid to the cabinet when the invalidity of the signal is indicated to close a valve for filling said cabinet when the signal from said pressure sensor is less than said sensor error signal.

6. A washer overfill protection system comprising:

a pressure sensor configured to generate a variable frequency signal that is proportional to the fluid level of the washer;

a converter electrically coupled to said pressure sensor, said converter configured to generate voltage that is proportional to the frequency of the output of said pressure sensor;

a microprocessor electrically coupled to said converter, said microprocessor configured to calculate the fluid level from the voltage of said converter, said microprocessor is electrically coupled to a fluid valve, said fluid valve including a coil; and

a backup circuit having fixed logic, said backup circuit electrically coupled to said converter and said fluid valve, said backup circuit is configured to at least one of turn on said fluid valve and turn off said fluid valve when said microprocessor fails, said backup circuit including an overfill comparator that compares the signal from said pressure sensor with an overfill reference signal to indicate an overfill condition and a sensor error comparator that compares the signal from said pressure sensor to a sensor error voltage to indicate an invalidity of the signal from said pressure sensor, said backup circuit acting independently of said microprocessor to disable a flow of fluid to the washer when the overfill condition is indicated, and said backup circuit acting independently of said microprocessor to disable a flow of fluid to the washer when the invalidity of the signal is indicated.

7. A washer overfill protection system according to claim 6 , wherein said overfill comparator is electrically coupled to said fluid valve.

8. A washer overfill protection circuit according to claim 7 , wherein said fluid valve coil is energized when said converter output voltage is less than the overfill reference voltage.

9. A washer overfill protection system according to claim 6 , wherein said sensor error comparator is electrically coupled to said fluid valve.

10. A washer overfill protection circuit according to claim 9 , wherein said fluid valve coil is energized when said converter output voltage is greater than the sensor error voltage.

11. A washer overfill protection circuit according to claim 9 , wherein said fluid valve coil is de-energized when said converter output voltage is lower than the sensor error voltage.

12. A washer overfill protection circuit according to claim 7 , wherein said fluid valve coil is de-energized when said converter output voltage is greater than the overfill reference voltage.

13. A washing machine comprising:

a cabinet;

a tub and basket mounted within said cabinet;

a pressure sensor coupled to said cabinet;

a cold water valve for controlling a cold water flow to said tub;

a hot water valve for controlling a hot water flow to said tub; and

a circuit coupled to at least one of said hot water valve and said cold water valve to control opening and closing of said hot and cold water valves, said circuit including a processor programmed to prevent overfilling of said cabinet and a backup circuit having fixed logic, said backup circuit electrically coupled to said processor to redundantly prevent overfilling said cabinet, said backup circuit including an overfill comparator that compares the signal from said pressure sensor with an overfill reference signal to indicate an overfill condition and a sensor error comparator that compares the signal from said pressure sensor to a sensor error voltage to indicate an invalidity of the signal from said pressure sensor, said backup circuit acting independently of said processor to disable at least one of the cold water flow and the hot water flow to the cabinet when the overfill condition is indicated, and said backup circuit acting independently of said processor to disable at least one of the cold water flow and the hot water flow to the cabinet when the invalidity of the signal is indicated.

14. A washing machine according to claim 13 , wherein said pressure sensor is electrically coupled to said backup circuit for measuring a fluid level in said cabinet, said pressure sensor generates a signal that is proportional to the fluid level.

15. A washing machine according to claim 14 , wherein said processor calculates the fluid level based on the signal from said pressure sensor.

16. A washing machine according to claim 14 , wherein said overfill comparator comprises a first operation amplifier for comparing the signal from said pressure sensor with said overfill reference signal and said sensor error comparator comprises a second operation amplifier for comparing the signal from said pressure sensor with said sensor error voltage.

17. A washing machine according to claim 13 , wherein said backup circuit acts independently of said processor to disable at least one of the cold water flow and the hot water flow to the cabinet when the overfill condition is indicated to close at least one of said cold water valve and said hot water valve if the signal from said pressure sensor is greater than the overfill reference signal.

18. A washing machine according to claim 13 , wherein said backup circuit acts independently of said processor to disable at least one of the cold water flow and the hot water flow to the cabinet when the invalidity of the signal is indicated to close at least one of said cold water valve and said hot water valve for filling said cabinet if the signal from said pressure sensor is less than the sensor error signal.