Offset Valve Bore in Reciprocating Pump Fluid End
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Solution Overview
Problem
Reciprocating pumps used in oil field operations experience high stress at the intersection of plunger bores with suction and discharge valve bores, leading to reduced operational life, especially at high pressures like 20,000 psi.
Innovation Solution
Inwardly offsetting at least one axis of the suction and discharge valve bores relative to their respective plunger bores in a fluid end configuration, which reduces stress concentrations and extends the operational life of the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the valve bores are arranged perpendicular to the plunger bore axis (conventional configuration), then the pump can achieve compact size and standard valve bore positioning, but high stress concentrations occur at the intersection points reducing operational life
Solution Approach 1:
The patent applies asymmetry by offsetting the valve bore axes from perpendicular alignment with the plunger bore axis. Specifically, the suction valve bore axis is offset at an angle of 10-45 degrees and the discharge valve bore axis is offset at an angle of 45-80 degrees relative to the plunger bore axis. This asymmetric arrangement eliminates the direct intersection of bores, thereby reducing stress concentration at intersection points and extending the operational life of the fluid end.
2Duration of action of stationary object
If the valve bores are offset inwardly from the plunger bore axis, then stress concentrations are reduced extending operational life, but the pump configuration becomes more complex and manufacturing more difficult
Solution Approach 1:
The patent employs parameter changes by specifying precise angular offsets for the valve bores relative to the plunger bore axis. The suction valve bore is offset at 10-45 degrees and the discharge valve bore at 45-80 degrees. These parameter specifications provide a balanced solution that reduces stress concentrations while maintaining manufacturability through defined geometric relationships.
3Productivity
If the valve bores are moved outwardly to increase volume (as in JP 2000-170643), then pump speed and volumetric flow can be increased, but stress within the pump increases and material between bores is reduced
Solution Approach 1:
The patent inverts the conventional approach by offsetting valve bores inwardly rather than outwardly. While JP 2000-170643 moves valve bores outward to increase volume, this patent moves them inward to reduce stress. The inward offset creates sufficient material between bores to handle high stresses while maintaining adequate valve bore volumes for acceptable flow capacity.
Data Source
AI summary
A fluid end (15) for a multiple reciprocating pump assembly (12) comprises at least three plunger bores (61) or (91) each for receiving a reciprocating plunger (35), each plunger bore having a plunger bore axis (65) or (95). Plunger bores being arranged across the fluid head to define a central plunger bore and lateral plunger bores located on either side of the central plunger bore. Fluid end (15) has suction valve bores (59) or (89), each suction valve bore receiving a suction valve (41) and having a suction valve bore axis (63) or (93). Discharge valve bores (57) or (87), each discharge valve bore receiving a discharge valve (43) and having a discharge valve bore axis (63) or (93). The axes of at least one of suction and discharge valve bores is inwardly offset in the fluid end from its respective plunger bore axis.