Filter assembly

Claim 2

A filter assembly comprising an Elongated filter element having first and second opposing sides, a housing forming with said filter element an elongated chamber on said first side of said filter element for receiving fluid to be filtered, means for collecting filtered fluid passing through said filter element to said second side thereof, a free piston having first and second opposing sides and being movable within said chamber between first and second positions toward opposite ends of said chamber, respectively, means for introducing fluid to be filtered under pressure to said chamber on said first side of said piston to hold said piston in said first position, means for opening said chamber on said first side of said piston, and means for introducing fluid to be filtered under pressure to said chamber on said second side of said piston to move said piston from said first position to said second position for removing the contents of said chamber.

Claim 3

A filter assembly according to claim 1 wherein said filter element is tubular and wherein said first and second opposing sides thereof are coaxial cylindrical surfaces.

Claim 4

A filter assembly according to claim 2 wherein said piston includes at least one annular scraper thereon for cleaning said first side of said filter element when said piston is moved.

Claim 5

A filter assembly comprising an elongated tubular filter element having first and second coaxial opposing sides, a housing forming with said filter element an elongated first chamber on said second side of said filter element, the interior of said filter element constituting a second chamber for receiving fluid to be filtered, means for collecting filtered fluid passing through said filter element to said second side thereof, a free piston having first and second opposing sides and being movable within said second chamber between first and second positions toward opposite ends of said second chamber, respectively, means for introducing fluid to be filtered under pressure to said second chamber on said first side of said piston to hold said piston in said first position, means for opening said second chamber on said first side of said piston, and means for introducing fluid to be filtered under pressure to said second chamber on said second side of said piston to move said piston from said first position to said second position for removing the contents of said second chamber.

Claim 6

A filter assembly comprising an elongated tubular filter element having first and second coaxial opposing sides, a housing forming with said filter element an elongated first chamber on said second side of said filter element, the interior of said filter element constituting a second chamber for receiving fluid to be filtered, means for collecting filtered fluid passing through said filter element to said second side thereof, a free piston having first and second opposing sides and being movable within said second chamber between first and second positions toward opposite ends of said second chamber, respectively, means for introducing fluid to be filtered under pressure to said second chamber on said first side of said piston to hold said piston in said first position, means for opening said second chamber on said first side of said piston, and means for introducing fluid to be filtered under pressure to said second chamber on said second side of said piston to move said piston from said first position to said second position for removing the contents of said second chamber.

Claim 7

A filter assembly according to claim 2 wherein said first side of said filter element is the exterior surface, wherein said chamber surrounds a substantial portion of said filter element, and wherein said piston is annular in shape and surrounds said filter element coaxial therewith.

Claim 8

A filter assembly according to claim 1 wherein said introducing means comprise a valve operable between two states for directing fluid under pressure to said chamber on said first and second sides of said piston, respectively.

Claim 9

A filter assembly according to claim 6 wherein said opening means comprise a normally closed first port in said housing opening to said chamber at one end thereof and on said first side of said piston, said port being openable to allow said piston to push the contents of said chamber therethrough.

Claim 10

A filter assembly according to claim 7 wherein said housing is provided with a normally closed second port therein opening to said chamber at one end thereof and on said second side of said piston, said second port being openable to allow said piston to push the contents of said chamber through said second port when said piston is returned from said second position to said first position thereof.

Claim 11

A filter assembly according to claim 8 wherein said piston includes a pair of annular scrapers thereon on said first and second sides, respectively, for cleaning said filter element, whereby said valve may be switched from one state to the other after predetermined periods of operation to periodically clean said filter element.

Claim 12

A filter assembly according to claim 8 wherein said piston has a single portion thereon on said first side for cleaning said filter, and wherein said valve is operable from one state to the other after a predetermined period of operation to clean said filter element, and is operable immediately thereafter back to its original state to return said piston to said first position.

Claim 13

A filter assembly according to claim 6 including means for sensing a predetermined condition in said filter assembly requiring movement of said piston, and means for operating said valve from one state to the other in response to the sensing of the predetermined condition.