Filter

• US 8,551,227 B2
• Filed: 07/15/2010
• Issued: 10/08/2013
• Est. Priority Date: 07/24/2009
• Status: Expired due to Fees

• Current Assignee: Dyson Technology Limited (Beeswax Holdings UK Limited)
• Original Assignee: Dyson Technology Limited (Beeswax Holdings UK Limited)
• Inventors: Horne, Lucas
• Primary Examiner(s): Chiesa, Richard L
• Application Number:
  US12/837,166
• Publication Number:
  US 20110016662A1
• Time in Patent Office: 1,181 Days
• Field of Search: 96/66, 96/73, 96/97, 96/96, 554/86, 554/87, 55D/IG.1, 55D/IG.3
• US Class Current: 96/66
• CPC Class Codes: A47L 9/10 Filters in general B01D; cyclones B04C; Dust separators; Dust removal; Automatic exchange of filters for machines for cleaning floors A47L11/40
• CPC Class Codes: A47L 9/12 Dry filters
• CPC Class Codes: B03C 3/017 Combinations of electrostatic separation with other processes, not otherwise provided for
• CPC Class Codes: B03C 3/025 Combinations of electrostatic separators, e.g. in parallel or in series, stacked separators or dry-wet separator combinations
• CPC Class Codes: B03C 3/15 Centrifugal forces
• CPC Class Codes: B03C 3/155 Filtration
• CPC Class Codes: B03C 3/30 in which electrostatic charge is generated by passage of the gases, i.e. tribo-electricity
• CPC Class Codes: B03C 3/41 Ionising-electrodes

Abstract

The present invention relates to an electrostatic filter. Particularly but not exclusively the invention relates to an electrostatic filter for removing dust particles, for example an electrostatic filter for use in a vacuum cleaner, fan or air conditioner. The electrostatic filter includes a filter medium located between a first and a second electrode, each at a different voltage during use, such that a potential difference is formed across the filter medium, wherein a property of the filter medium varies along the length of the filter medium.

Claims

1. An electrostatic filter comprising:

an electrically resistive filter medium located between a first and a second electrode, each at a different voltage during use, such that a potential difference is formed across the filter medium,

wherein electrical resistivity of the filter medium varies along a length of the filter medium.

2. The electrostatic filter of claim 1, wherein the average pore diameter, the pores per inch and/or the type of filter medium varies along the length of the filter medium.

3. The electrostatic filter of claim 1, wherein the variation occurs in a single filter medium.

4. The electrostatic filter of claim 1, wherein a plurality of sections of filter medium are brought together to form the filter medium.

5. The electrostatic filter of claim 2, wherein the pores per inch increase in a downstream direction.

6. The electrostatic filter of claim 2, wherein the average pore size decreases in a downstream direction.

7. The electrostatic filter of claim 1, wherein the electrical resistivity decreases in a downstream direction.

8. The electrostatic filter of claim 1, wherein the filter medium comprises an open cell reticulated foam.

9. The electrostatic filter of claim 1, wherein the first and second electrodes are substantially non-porous.

10. The electrostatic filter of claim 9, wherein the first and second electrodes are non-porous along their entire length.

11. The electrostatic filter of claim 1, wherein the filter medium is in contact with the first and/or the second electrode.

12. The electrostatic filter of claim 1, further comprising at least one corona discharge means.

13. The electrostatic filter of claim 1, wherein the first and/or second electrode is formed from a conductive metal sheet or foil of from 0.1 mm to 4 mm in thickness.

14. A vacuum cleaner comprising the electrostatic filter of claim 1.