Dual flow filter

• US 20030168397A1
• Filed: 10/15/2002
• Published: 09/11/2003
• Est. Priority Date: 02/19/2000
• Status: Active Grant

• Current Assignee: Masterfilter Limited
• Original Assignee: Alan Philip Roper, Michael Charles Fallows
• Inventors: Roper, Alan Philip, Fallows, Michael Charles
• Granted Patent: US 6,893,555 B2
• Time in Patent Office: Days
• US Class Current: 210/348
• CPC Class Codes: B01D 2201/4015 Bayonet connecting means
• CPC Class Codes: B01D 2201/46 Several filtrate discharge conduits each connected to one filter element or group of filter elements
• CPC Class Codes: B01D 27/02 with cartridges made from a mass of loose granular or fibrous material
• CPC Class Codes: B01D 27/07 having a coaxial stream through the filtering element
• CPC Class Codes: B01D 27/144 arranged concentrically or coaxially
• CPC Class Codes: Y10S 210/13 Part flow-full flow
• CPC Class Codes: Y10S 210/17 Twist-on

Abstract

A dual flow filter unit for the filtration of a pressurized liquid such as oil, comprising a closed housing (10) having an inlet (31), and main and secondary outlets (32, 13) for that liquid. The unit further comprises a main filter element (21) arranged in the housing (10) and having an unfiltered fluid surface exposed to the majority of the liquid flow, the flow through the main filter (21) being directed to the main outlet (32) from the housing (10); and a secondary filter element (17) exposed to a portion of the liquid flow supplied to the housing inlet (31), any flow through the secondary filter being directed to the secondary outlet (13) from the housing. The main filter element (21) offers a low resistance to the flow of fluid therethrough relative to the secondary filter element (17) so that the majority of the flow through the inlet (31) is filtered by the main filter element (21) and the remainder by the secondary filter element (17). This allows better filtration of the liquid without adversely affecting the flow rate or pressure thereof.

Claims

1. A filter unit for the filtration of a pressurised liquid comprising:

a closed housing having an inlet for liquid to be filtered, and main and secondary outlets for liquid which has been filtered;

a main filter element arranged in the housing and having an unfiltered fluid surface exposed to the majority of the liquid flow supplied under pressure to the housing inlet, flow through the main filter being directed to the main outlet from the housing;

a secondary filter element having an unfiltered fluid surface exposed to a portion of the liquid flow supplied under pressure to the housing inlet, flow through the secondary filter being directed to the secondary outlet from the housing;

wherein the main filter element offers a low resistance to the flow of fluid therethrough relative to the secondary filter element so that the majority of the flow through the inlet is filtered by the main filter element and the remainder by the secondary filter element.

2. A filter unit as claimed in claim 1, wherein the housing is substantially cylindrical, with a one end and an other end.

3. A filter as claimed in claim 2, wherein the inlet and main outlet are formed in the one end.

4. A filter unit as claimed in claim 2 or claim 3, wherein the second outlet is formed in the other end of the housing.

5. A filter unit as claimed in any of claim 2 to claim 4, wherein the main filter element is adjacent the one end of the housing and is cylindrical with a diameter slightly less than the housing, and the unfiltered fluid surface thereof being disposed toward the curved surface of the housing.

6. A filter unit as claimed in either of claim 4 or claim 5, wherein the secondary filter element is adjacent the other end of the housing.

7. A filter unit as claimed in any of claim 2 to claim 6, wherein the one end of the housing is formed from an end cap.

8. A filter unit as claimed in claim 7, wherein the end cap is removably connected to the housing to allow servicing of filter elements.

9. A filter unit as claimed in claim 8, wherein the main and secondary filter elements may be replaced individually.

10. A filter unit as claimed in any of the preceding claims, wherein the main filter element is a pleated paper filter.

11. A filter unit as claimed in any of the preceding claims, wherein the secondary filter element is a compressed fibre filter.

12. A filter unit as claimed in any of the preceding claims, wherein a metering jet is provided in the secondary outlet.

13. A filter as claimed in any of the preceding claims, wherein a non-return valve is provided in the inlet.

14. A filter unit as claimed in any of the preceding claims, wherein a biasing spring is provided between the main filter element and the secondary filter element, which spring holds them apart to form an inner chamber within the container.

15. A filter unit as claimed in any of claim 1 to claim 7 or claim 10 to claim 14, wherein the housing is a sealed unit and the entire filter unit is replaceable.

16. A filter unit as claimed in any of the preceding claims, wherein the secondary outlet is adapted for attachment to a return pipe.