ROTATING FILTER FOR A DISHWASHING MACHINE

• US 20110146714A1
• Filed: 12/13/2010
• Published: 06/23/2011
• Est. Priority Date: 12/21/2009
• Status: Active Grant

• Current Assignee: Whirlpool Corporation
• Original Assignee: Whirlpool Corporation
• Inventors: FOUNTAIN, JORDAN R., WELCH, RODNEY M.
• Granted Patent: US 8,667,974 B2
• Time in Patent Office: Days
• US Class Current: 134/10
• CPC Class Codes: A47L 15/4206 Tubular filters
• CPC Class Codes: A47L 15/4208 Arrangements to prevent clogging of the filters, e.g. self-cleaning
• CPC Class Codes: A47L 15/4219 Water recirculation A47L15/0078 takes precedence

Abstract

A dishwasher with a tub at least partially defining a washing chamber, a liquid spraying system, a liquid recirculation system defining a recirculation flow path, and a liquid filtering system. The liquid filter system includes a rotating filter disposed in the recirculation flow path to filter the liquid.

Claims

1. A method of operating a dishwasher comprising a washing chamber holding utensils for washing, sprayers for spraying liquid on the utensils, and a liquid recirculation system, for recirculating sprayed liquid back to the sprayers, and including a filter for filtering the liquid, the filter having a downstream surface confronting unfiltered liquid, and an upstream surface confronting filtered liquid, the method comprising:

spraying liquid within the washing chamber;

recirculating the sprayed liquid for subsequent spraying;

rotating the filter within the liquid during the recirculating of the liquid;

applying a shear force on the downstream surface, with a magnitude of the shear force being greater than the shear force attributable to the filter rotating in liquid; and

wherein the applied shear force aids in a removal of soils on the downstream surface.

2. The method of claim 1 wherein the applying the shear force comprises locally increasing the shear force attributable to an interaction of the liquid and the rotating filter.

3. The method of claim 2 wherein the locally increasing the shear force comprises constraining the liquid on a downstream side of the filter.

4. The method of claim 3 wherein the constraining the liquid on the downstream side of the filter comprises creating an artificial boundary on the downstream side of the filter.

5. The method of claim 4 wherein the creating the artificial boundary comprises creating an artificial boundary that forms a high pressure area between the artificial boundary and the downstream surface.

6. The method of claim 1, further comprising backwashing the filter during the rotation of the filter by generating a backwash liquid flow from the upstream surface to the downstream surface along at least a portion of the filter.

7. The method of claim 6 wherein the generation of the backwash liquid flow comprises generating a lower pressure on the downstream surface than on an opposing portion of the upstream surface.

8. The method of claim 7 wherein the generating the lower pressure on the downstream surface than on the opposing portion of the upstream surface comprises at least one of generating a high pressure area on the upstream surface and generating a low pressure area on the downstream surface.

9. The method of claim 7, further comprising forming a stream of liquid passing through the filter, from a downstream side to an upstream side, at a location rotationally in front of the backwash liquid flow such that at least a portion of the stream of liquid becomes part of the backwash liquid flow and is returned to the downstream side of the filter.

10. The method of claim 1, further comprising applying a shear force on the upstream surface to aid in the removal of soil on the upstream surface, with a magnitude of the shear force being greater than the shear force attributable to the filter rotating in liquid.

11. A method of operating a dishwasher comprising a washing chamber holding utensils for washing, sprayers for spraying liquid on the utensils, and a liquid recirculation system, for recirculating sprayed liquid back to the sprayers, and including a filter for filtering the liquid, the filter having an downstream surface confronting unfiltered liquid, and an upstream surface confronting filtered liquid, the method comprising:

spraying liquid within the washing chamber;

recirculating the sprayed liquid for subsequent spraying;

rotating the filter within the liquid during the recirculating of the liquid;

backwashing the filter during the rotation of the filter along at least a portion of the filter; and

wherein the backwashing aids in a removal of soils on the downstream surface.

12. The method of claim 11 wherein the backwashing the filter during the rotation of the filter comprises generating a backwash liquid flow from the upstream surface to the downstream surface.

13. The method of claim 12 wherein the generating the backwash liquid flow comprises generating a lower pressure on the downstream surface than on an opposing portion of the upstream surface.

14. The method of claim 13 wherein the generating a lower pressure on the downstream surface than on the opposing portion of the upstream surface comprises at least one of generating a high pressure area on the upstream surface and generating a low pressure area on the downstream surface.

15. The method of claim 14 wherein the generating a backwash liquid flow further comprises creating an artificial boundary on an upstream side of the filter to generate a high pressure area.

16. The method of claim 15 wherein the generating a backwash liquid flow further comprises creating an artificial boundary on a downstream side of the filter to generate a low pressure area opposite the high pressure area.

17. The method of claim 11, further comprising forming a stream of liquid passing through the filter, from a downstream side to an upstream side, at a location rotationally in front of a backwash liquid flow such that at least a portion of the stream of liquid becomes part of the backwash liquid flow and is returned to the downstream side of the filter.

18. A dishwasher comprising:

a tub at least partially defining a washing chamber;

a liquid spraying system supplying a spray of liquid to the washing chamber;

a liquid recirculation system recirculating the sprayed liquid from the washing chamber to the liquid spraying system to define a recirculation flow path; and

a liquid filtering system comprising;

a rotating filter having a downstream surface and an upstream surface and located within the recirculation flow path such that the sprayed liquid passes through the filter from the downstream surface to upstream surface to effect a filtering of the sprayed liquid; and

a first artificial boundary overlying at least a portion of the downstream surface to form an increased shear force zone therebetween;

wherein liquid passing between the first artificial boundary and the rotating filter applies a greater shear force on the downstream surface than liquid in an absence of the first artificial boundary.

19. The dishwasher of claim 18 wherein there are multiple first artificial boundaries spaced about the rotating filter to define multiple increased shear force zones.

20. The dishwasher of claim 19 wherein the multiple artificial boundaries are provided on both the upstream side and downstream side of the rotating filter.

21. The dishwasher of claim 20 wherein the multiple artificial boundaries are arranged in pairs, with each pair having one artificial boundary on the upstream side and another artificial boundary on the downstream side of the rotating filter.

22. The dishwasher of claim 18 wherein a distance between the first artificial boundary and the downstream surface decreases in a direction opposite a rotational direction of the filter to form a constriction point.

23. The dishwasher of claim 22 wherein the distance between the first artificial boundary and the downstream surface increases from the constriction point in a direction along the rotational direction of the filter to form a liquid expansion zone.

24. The dishwasher of claim 23, further comprising a second artificial boundary overlying the upstream surface and forming a liquid pressurizing zone opposite a portion of the first artificial boundary.

25. The dishwasher of claim 24 wherein the distance between the second artificial boundary and the upstream surface decreases in a direction along the rotational direction of the filter to form the liquid pressurizing zone.

26. The dishwasher of claim 25 wherein the filter is cylindrical, the first artificial boundary is a concave shroud terminating in an increased thickness portion to define the constriction point, and the second artificial boundary comprising a concave deflector.

27. The dishwasher of claim 26 wherein the concave deflector terminates prior to the constriction point.

28. The dishwasher of claim 26 wherein there are corresponding pairs of shrouds and deflectors spaced about the filter.

29. The dishwasher of claim 28 wherein the deflectors extend axially within the filter and form flow straighteners.

30. The dishwasher of claim 26 wherein the deflector has an S-shape cross section and extends axially within the filter to form a flow straightener.

31. The dishwasher of claim 26 wherein the filter is cylindrical, the first artificial boundary is a concave shroud terminating in an increased thickness portion to define the constriction point, and the second artificial boundary has a multi-pointed star shape in cross section and extends axially within the filter to form a flow straightener.

32. The dishwasher of claim 23, further comprising a second artificial boundary overlying the upstream surface to form an increased shear force zone therebetween.

33. The dishwasher of claim 18 wherein a distance between the first artificial boundary and the downstream surface decreases in a direction along a rotational direction of the filter to form a constriction point.

34. The dishwasher of claim 33 wherein the distance between the first artificial boundary and the downstream surface increases from the constriction point in a direction along the rotational direction of the filter to form a liquid expansion zone.

35. The dishwasher of claim 34 further comprising a second artificial boundary overlying the upstream surface and forming a liquid pressurizing zone opposite a portion of the first artificial boundary.

36. The dishwasher of claim 35 wherein the distance between the second artificial boundary and the upstream surface decreases in a direction along the rotational direction of the filter to form the liquid pressurizing zone.

37. The dishwasher of claim 36 wherein the filter is cylindrical, the first artificial boundary is a concave shroud terminating in an increased thickness portion to define the constriction point, and the second artificial boundary comprising a concave deflector.

38. The dishwasher of claim 37 wherein the concave deflector terminates prior to the constriction point.

39. The dishwasher of claim 37 wherein there are corresponding pairs of shrouds and deflectors spaced about the filter.

40. The dishwasher of claim 39 wherein the deflectors extend axially within the filter and form flow straighteners.

41. The dishwasher of claim 37 wherein the deflector has an S-shape cross section and extends axially within the filter to form a flow straightener.

42. The dishwasher of claim 37 wherein the filter is cylindrical, the first artificial boundary is a concave shroud terminating in an increased thickness portion to define the constriction point, and the second artificial boundary has a multi-pointed star shape in cross section and extends axially within the filter to form a flow straightener.

43. The dishwasher of claim 33, further comprising a second artificial boundary overlying the upstream surface to form an increased shear force zone therebetween.

44. The dishwasher of claim 18, further comprising a sump fluidly coupled to the tub and the rotating filter is located within the sump.

45. The dishwasher of claim 44 further comprising a housing physically remote from the tub and defining the sump.

46. The dishwasher of claim 45 wherein the recirculation system further comprises a recirculation pump having an inlet fluidly coupled to an upstream side of the filter.

47. The dishwasher of claim 46 wherein the pump further comprises an impeller and the filter is mounted to the impeller such that the rotation of the impeller rotates the filter.

48. A dishwasher comprising:

a tub at least partially defining a washing chamber;

a liquid spraying system supplying a spray of liquid to the washing chamber;

a liquid recirculation system recirculating the sprayed liquid from the washing chamber to the liquid spraying system to define a recirculation flow path; and

a liquid filtering system comprising;

a rotating filter having a downstream surface and an upstream surface and located within the recirculation flow path such that the sprayed liquid passes through the filter from the downstream surface to upstream surface to effect a filtering of the sprayed liquid; and

a first artificial boundary overlying at least a portion of one of the downstream surface and one of the upstream surface to form one of a liquid expansion zone and a liquid pressurized zone, respectively, therebetween;

wherein liquid will backwash from the upstream surface to the downstream surface in response to the one of the liquid expansion zone and the liquid pressurized zone.

49. The dishwasher of claim 48, further comprising a second artificial boundary overlying the at least a portion of the upstream surface to form the liquid pressurized zone, with the first artificial boundary overlying the downstream surface to form the liquid expansion zone.

50. The dishwasher of claim 49 wherein the distance between the first artificial boundary and the downstream surface increases in a direction along a rotational direction of the filter to form a liquid expansion zone.

51. The dishwasher of claim 50 wherein the distance between the second artificial boundary and the upstream surface decreases in a direction along the rotational direction of the filter to form the liquid pressurizing zone.