A self-cleaning fuel oil strainer, coupled to a continuous fuel flow, that includes a pair of canisters, each having a cylindrical wedge wire fuel oil filter screen. An elongated brush running the length of the screen is disposed between two confining walls also running the length of the screen to form a chamber. A elongated partition, including two sets of apertures, is used, along with the elongated brush, to divide the chamber into two particulate dislodge chambers and a drain subchamber. A drain is in fluid communication with the drain subchamber. During cleaning, the drain is opened and the screen is rotated against the brush for liberating the particulate contaminants and a limited amount of fuel oil into the two dislodge subchambers. The particulate contaminants and the limited amount of fuel oil then pass through the apertures at a high velocity and into the drain subchamber which exits through the drain. Alternatively, a reverse flow of clean fuel oil can be used in combination with the elongated brush, for dislodging the particulate contaminants from the fuel oil filter screen. Finally, another variation of using a reverse flow of clean fuel oil for cleaning purposes is discussed whereby a stationary fuel oil strainer is disposed in a system that isolates the fuel oil strainer from the normal fuel oil flow during cleaning.
We claim:1. A strainer for removing particulates from a fluid flow, said strainer comprising:a stationary cylindrical porous member disposed in the fluid flow and having a first outer surface upstream of the flow and a second inner surface downstream of the flow, the particulates lodging against said first outer surface, said stationary cylindrical porous member defining an inner region;a single ultrasonic energy source contained within a housing, wherein said ultrasonic energy source and housing are positioned inside said inner region adjacent said second inner surface for dislodging particulates from said first outer surface; and means for backwashing that convey a reverse flow of a clean fluid from said second inner surface through said first outer surface to evacuate said dislodged particulates from returning to said first outer surface. 2. The strainer of claim 1 wherein said means for backwashing operates without the use of a nozzle. 3. The strainer of claim 1 wherein said clean fluid comprises said fluid flow that has already passed through said second inner surface. 4. A method for removing particulates from a strainer positioned in a first fluid flow having particulates therein, said method comprising the steps of: disposing a first outer surface of a stationary cylindrical porous member in the first fluid flow to capture particulates against said first outer surface; positioning a housing containing a single ultrasonic energy source within an inner region of said stationary cylindrical porous member defined by a downstream second inner surface of said stationary cylindrical porous member, said second inner surface permitting passage of a cleaned fluid flow; isolating said stationary cylindrical porous member from said first fluid flow; activating said ultrasonic energy source to dislodge particulates from said first outer surface; and sending a reverse flow of a clean fluid through said second inner and first outer surfaces to evacuate said dislodged particulates from returning to said first outer surface. 5. The method of claim 4 wherein said step of sending a reverse flow of a clean fluid comprises sending a reverse flow of said first fluid flow that has already passed through said second surface. 6. A method for reducing the amount of cleaned fluid required in cleaning a particulate strainer using a reverse flow system, said method comprising the steps of: disposing a stationary cylindrical strainer in a first fluid flow to capture particulates against a first upstream surface of the strainer; positioning a housing containing a single ultrasonic energy source within an inner region of said stationary cylindrical strainer defined by a downstream second surface, said second surface permitting passage of a cleaned fluid flow; stopping said first flow; activating said ultrasonic energy source to dislodge particulates from said first surface; sending a reverse flow of said cleaned fluid flow through said second surface and through said first surface to evacuate said dislodged particulates from returning to said first surface; and restoring the passage of said first flow through said strainer.