Patent ID: 8858187

Claim:
A downhole pump, comprising a barrel having a first one-way valve restricting fluid passage out of the barrel; a plunger reciprocally disposed in the barrel and having first and second seals with the plunger and the barrel, the plunger having a second one-way valve restricting fluid passage out of an interior of the plunger and into a variable volume defined between the first and second one-way valves; and a screen disposed on the plunger between the first and second seals and separating the interior of the plunger from a gap between the plunger and the barrel, the screen permitting fluid passage between the interior and the gap and restricting particulate in the interior from passing into the gap, the screen comprising profiled wire forming a plurality of slotted openings, narrower portions of the slotted openings facing the interior of the plunger, where in a first stroke moving the barrel and the plunger relative to one another in a first direction, the variable volume decreases, the first one-way valve closes, and the second one-way valve opens, and where in the first stroke, fluid entering the interior of the plunger from the variable volume through the second one-way valve clears particulate adjacent a face of the wire on the screen exposed to the interior of the plunger.