System and method for determining filter condition

• US 20030070544A1
• Filed: 10/15/2002
• Published: 04/17/2003
• Est. Priority Date: 10/15/2001
• Status: Abandoned Application

• Current Assignee: Hamilton Beach/Proctor-Silex Incorporated (Hamilton Beach Brands Holding Co.)
• Original Assignee: Hamilton Beach/Proctor-Silex Incorporated (Hamilton Beach Brands Holding Co.)
• Inventors: Hak, Marron, Mulvaney, Patrick T.
• Application Number:
  US10/271,481
• Publication Number:
  US 20030070544A1
• Time in Patent Office: Days
• US Class Current: 95/25
• CPC Class Codes: B01D 2273/30 Means for generating a circulation of a fluid in a filtration system, e.g. using a pump or a fan
• CPC Class Codes: B01D 46/0086 Filter condition indicators
• CPC Class Codes: B01D 46/44 controlling filtration

Abstract

A system and method for determining the condition of a filter in a forced air filtration system includes a blower motor and a fan mounted for rotation with an output shaft of the blower motor. A load sensor is operably connected to the blower motor for monitoring an electric load of the motor. As the filter becomes increasingly laden with airborne particles, the electric load changes. The load sensor generates a load value dependent on the electric load of the motor which is compared to a predetermined value. When the load value reaches the predetermined value, a signal is generated indicative of a filter change condition.

Claims

1. A forced air filtration system comprising:

a housing having an air inlet and an air outlet;

an air filter positioned in an airflow pathway between the air inlet and the air outlet;

a blower assembly having an electric motor with an output shaft and a fan mounted for rotation with the output shaft, the blower assembly being positioned for directing air flow from the air inlet, through the air filter and out of the air outlet;

circuitry operably connected to the electric motor, the circuitry comprising a load sensor for monitoring an electric load of the motor, the load sensor generating a load value dependent on the electric load of the motor; and

an indicator for indicating a condition of the air filter based on the load value.

2. A forced air filtration system according to claim 1, wherein the load sensor comprises a current sensor for measuring a current draw of the electric motor.

3. A forced air filtration system according to claim 2, wherein the current sensor comprises an ammeter connected in series with the electric motor.

4. A forced air filtration system according to claim 3, wherein the indicator comprises:

a display having graphical representation depicting at least a change filter condition; and

a needle operably associated with the ammeter, the needle being movable with respect to the display in response to a change in the current draw of the electric motor to thereby indicate the change filter condition.

5. A forced air filtration system according to claim 4, wherein the graphical representation comprises indicia.

6. A forced air filtration system according to claim 4, wherein the graphical representation comprises a first graphical portion indicative an acceptable filter condition and a second graphical portion indicative of the change filter condition, the needle being movable between the first and second graphical portions.

7. A forced air filtration system according to claim 6, wherein the graphical representation further comprises a third graphical portion between the first and second graphical portions, the third graphical portion being indicative of a marginal filter condition.

8. A forced air filtration system according to claim 2, wherein the current sensor comprises a hall effect sensor for indirectly measuring the current draw of the electric motor.

9. A forced air filtration system according to claim 1, wherein the circuitry comprises a comparator electrically connected to the load sensor for comparing a value of the electric load of the motor to a predetermined value indicative of the filter condition.

10. A forced air filtration system according to claim 9, wherein the predetermined value is a constant current source.

11. A forced air filtration system according to claim 9, wherein the predetermined value is a stored value in a nonvolatile memory.

12. A forced air filtration system according to claim 1, wherein the load sensor comprises means for directly measuring the revolutions per minute of the electric motor.

13. A forced air filtration system according to claim 1, wherein the indicator comprises an audible device.

14. A forced air filtration system comprising:

a housing having an air inlet and an air outlet;

an air filter positioned in an airflow pathway between the air inlet and the air outlet;

a blower assembly having an electric motor with an output shaft and a fan mounted for rotation with the output shaft, the blower assembly being positioned for directing air flow through the air filter and out of the air outlet;

circuitry operably connected to the electric motor, the circuitry comprising;

a current sensor for measuring a current draw of the electric motor, the current sensor generating a load value dependent on the electric load of the motor; and

a comparator electrically connected to the current sensor for comparing the load value to a predetermined value indicative of a filter change point; and

an indicator operably associated with the comparator for indicating at least the filter change point.

15. A forced air filtration system according to claim 14, wherein the predetermined value is a constant current source.

16. A forced air filtration system according to claim 14, wherein the predetermined value is a stored value in a nonvolatile memory.

17. A forced air filtration system according to claim 14, and further comprising means for directly measuring the revolutions per minute of the electric motor.

18. A method for sensing a change point of a filter in a forced air filtration system having an electric blower motor and a fan connected to an output shaft of the blower motor for rotation therewith to thereby direct air through the filter, the method comprising:

monitoring an electric load of the blower motor;

generating a load value dependent on the electric load of the motor; and

indicating a change point of the air filter based on the load value.

19. A method according to claim 18, wherein monitoring the electric load comprises measuring a current draw of the blower motor.

20. A method according to claim 19, wherein measuring the current draw comprises providing an ammeter in series with the blower motor.

21. A method according to claim 20, wherein indicating a filter change point comprises:

displaying a graphical representation depicting at least a change filter condition; and

moving a needle operably associated with the ammeter with respect to the display in response to a change in the current draw of the blower motor to thereby indicate the filter change point.

22. A method according to claim 21, wherein displaying a graphical representation includes displaying a first graphical portion indicative an acceptable filter condition and a second graphical portion indicative of the filter change point, the needle being movable between the first and second graphical portions.

23. A method according to claim 22, wherein displaying a graphical representation further comprises displaying a third graphical portion between the first and second graphical portions, the third graphical portion being indicative of a marginal filter condition.

24. A method according to claim 19, wherein measuring the current draw comprises indirectly measuring the current draw of the electric motor.

25. A method of determining a filter life of an air filter used in a forced air filtration system to alert a user of a dirty-filter condition, the method comprising:

actuating a fan motor to force air through the air filter;

measuring a current passing through the fan motor;

determining a speed of the fan motor from the measured current;

comparing the speed of the fan motor to a predetermined value to determine the filter life; and

actuating an alert if the speed of the fan motor is greater than the predetermined value.