Fluid tank with kidney-loop filtration system

1. A return flow filtration assembly for providing both primary filtering and secondary type fine filtering of hydraulic return fluid comprising:

a return fluid chamber arrangement comprising a first inlet and first and second outlets;

primary and secondary return flow filters within the return fluid chamber arrangement; and

wherein at least one of the first and second outlets includes a restriction element for restricting flow through the at least one of the first and second outlets and increasing a pressure through that outlet to drive fluid through the other one of the at least one of the first and second outlets such that a portion of the fluid flow through the return fluid chamber arrangement passes through at least one of the primary and secondary return flow filters; and

a hydraulic fluid storage tank, the first and second outlets are in operable fluid communication with a reservoir defined by the hydraulic fluid storage tank; and

wherein the return fluid chamber arrangement is substantially positioned within the fluid storage tank.

2. The return flow filtration assembly of claim 1 , wherein the secondary return flow filter is coupled to the second outlet, the secondary return flow filter being fluidly interposed between the first inlet and the second outlet; the restriction element providing sufficient back pressure to the first outlet to force a portion of the fluid within the return fluid chamber arrangement through the secondary return flow filter.

3. The return flow filtration assembly of claim 2 , wherein the primary return flow filter is operably coupled to the first outlet and being fluidly interposed between the first inlet and the first outlet.

4. The return flow filtration assembly of claim 3 , wherein the primary and secondary return flow filters are arranged in parallel such that a first portion of a return fluid passes only through the primary return flow filter and the first outlet and a second portion of the fluid entering the first return fluid chamber passes only through the secondary return flow filter.

5. The return flow filtration assembly of claim 4 , wherein the return fluid chamber arrangement includes a plurality of chambers including a first return fluid chamber including the primary return flow filter and a secondary return fluid chamber including the secondary return flow filter, both chambers downstream from the first inlet.

6. The return flow filtration assembly of claim 5 , further comprising a fluid manifold upstream of both of the primary and secondary return fluid chambers and downstream of the first inlet, the manifold separating the fluid flow through the first inlet into the first and second portions of fluid.

7. The return flow filtration assembly of claim 6 , wherein the secondary return flow filter filters smaller particles from the fluid than the primary flow filter.

8. The return flow filtration assembly of claim 1 , wherein the return fluid chamber arrangement is comprised of a plurality of chambers including a first return fluid chamber and a second return fluid chamber, the primary return flow filter element within the first return fluid chamber and the secondary return flow filter element within the second return fluid chamber, wherein the first return flow filter element is interposed between the first inlet and both of the first and second outlets such that flow paths from the first inlet to the first and second outlets both pass through the first return fluid chamber and both flow paths pass through the primary return flow filter element.

9. The return flow filtration assembly of claim 8 , wherein the secondary return flow filter is within the second return fluid chamber and only forms part of the flow path from the first inlet to the first outlet, such that only the portion of the flow that passes through the first outlet passes through the secondary return flow filter, the restriction element providing sufficient back pressure to the second outlet to force the portion of the fluid through the secondary return flow filter, wherein the primary and secondary return flow filter are arranged in series such that all of the fluid that passes through the secondary return flow filter has previously passed through primary return flow filter, when the primary return flow filter is operating.

10. A return flow filtration assembly for providing both primary filtering and secondary type fine filtering of hydraulic return fluid comprising:

a return fluid chamber arrangement comprising a first inlet and first and second outlets;

primary and secondary return flow filters within the return fluid chamber arrangement;

wherein at least one of the first and second outlets includes a restriction element for restricting flow through the at least one of the first and second outlets and increasing a pressure through that outlet to drive fluid through the other one of the at least one of the first and second outlets such that a portion of the fluid flow through the return fluid chamber arrangement passes through at least one of the primary and secondary return flow filters;

wherein the return fluid chamber arrangement is comprised of a plurality of chambers including a first return fluid chamber and a second return fluid chamber, the primary return flow filter element within the first return fluid chamber and the secondary return flow filter element within the second return fluid chamber, wherein the first return flow filter element is interposed between the first inlet and both of the first and second outlets such that flow paths from the first inlet to the first and second outlets both pass through the first return fluid chamber and both flow paths pass through the primary return flow filter element;

wherein the secondary return flow filter is within the second return fluid chamber and only forms part of the flow path from the first inlet to the first outlet, such that only the portion of the flow that passes through the first outlet passes through the secondary return flow filter, the restriction element providing sufficient back pressure to the second outlet to force the portion of the fluid through the secondary return flow filter, wherein the primary and secondary return flow filter are arranged in series such that all of the fluid that passes through the secondary return flow filter has previously passed through primary return flow filter, when the primary return flow filter is operating; and

wherein the second outlet is not directly coupled to either the primary or secondary return flow filters and is freely exposed to the second return flow chamber such that the portion of flow that does not pass through the secondary return flow filter passes through the second return fluid chamber and out the second outlet.

11. The return flow filtration assembly of claim 10 , wherein the restriction element is a spring-loaded valve.

12. The return flow filtration assembly of claim 11 , wherein the spring-loaded valve is adjustable to vary the amount of back pressure provided.

13. The return flow filtration assembly of claim 1 , wherein the restriction element is a spring-loaded valve.

14. The return flow filtration assembly of claim 13 ,

wherein the spring-loaded valve is adjustable to vary the amount of back pressure provided.

15. The return flow filtration assembly of claim 1 , wherein a portion of the fluid flow through the first inlet passes through only one of the primary and secondary return flow filters.