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US 5,290,159 AGranted
Downhole pump of constant differential hydraulic pressure
AssigneeExxon Production Research Company
InventorsMark A. Miller, James D. Fox
Life of this patent
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Abstract
A combination low-pressure, high-pressure hydraulic pump which allows a constant differntial pressure is disclosed. This pump features dual concentric pistons, each with its own chamber. The pistons reciprocate together at low pressures; as the system pressure increases, a spring resists the stroke of the low pressure piston, so that ultimately only the smaller, high pressure piston reciprocates.
Claims7
A combination low pressure and high pressure hydraulic pump comprising:
- (a) a housing defining a longitudinal bore, which bore has a first chamber larger in diameter than a second chamber, and which first chamber and second chamber each contains an inlet and an outlet;
- (b) a cylindrical first piston sealingly mounted in said housing and adapted for reciprocating movement within the first chamber, which first piston defines a second longitudinal bore with essentially the same diameter as the second chamber;
- (c) a second piston sealingly mounted in said second longitudinal bore and adapted for reciprocating movement within said second longitudinal bore and said second chamber;
- (d) a spring to couple the first piston and the second piston at lower pressures, which lower pressures depend upon the spring constant of the spring;
- (e) means for reciprocating said pistons in said chambers;
- and
- (f) a connecting rod connecting said second piston to said reciprocating means.
4 more elements
Dependencies are inferred from the claim text.