Variable Displacement Reciprocating Pump with Eccentric Cam Mechanism
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Solution Overview
Problem
Current multi-plunger well service pumps are costly and inefficient due to the need for transmissions and multiple pumps to achieve a range of operating conditions, with limited control capabilities and potential for overloading, especially in high-pressure applications.
Innovation Solution
A variable displacement reciprocating pump system that adjusts the stroke of the pump plungers without a transmission, using a mechanism of adjustable outer and inner eccentric cams driven by a parallel intermediate shaft, allowing continuous control of displacement, pressure, and flow rate through a computer-controlled system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transmissions are used to control pump speed and achieve different operating conditions, then the pump can operate at high rates and low pressures or low rates and high pressures, but the system becomes more expensive, weighs more, takes up more space, and requires multiple pumps and engines
Solution Approach 1:
The patent removes the transmission component entirely from the pump system. Instead of using a transmission to control pump speed and achieve different operating conditions, the invention extracts this function and replaces it with a variable displacement mechanism that directly adjusts the pump's stroke length, thereby eliminating the need for complex gear systems and multiple pumps
Solution Approach 2:
The patent implements a dynamic displacement mechanism where the pump's stroke length can be continuously adjusted during operation. This is achieved through a variable eccentricity cam mechanism that allows the pump to change its displacement volume dynamically, providing adaptability across different operating conditions without requiring speed changes or multiple pumps
2Adaptability or versatility
If multiple pumps with different sizes are used to meet the full range of rates and pressures, then the required operating conditions can be achieved, but the cost, weight, and space requirements increase significantly
Solution Approach 1:
The patent creates a single pump system that can perform multiple functions across different operating conditions. By implementing variable displacement capability, one pump can replace what would traditionally require multiple pumps of different sizes, making the system universal and adaptable to various flow rate and pressure requirements
3Device complexity
If traditional fixed displacement pumps with transmissions are used, then the pump structure is simpler, but the pressure-volume curve is discontinuous and the working range is limited
Solution Approach 1:
The patent transforms the fixed displacement pump into a variable displacement pump by implementing a dynamic stroke adjustment mechanism. The variable eccentricity cam allows continuous adjustment of the plunger stroke length, creating a continuous and smooth pressure-volume curve while expanding the working range beyond what fixed displacement pumps can achieve
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces costs, increases operational flexibility, and prevents overloading by allowing continuous adjustment of pump output, enabling efficient operation at a wide range of pressures and flow rates with a single engine, while maintaining high power transmission capabilities.
Implementation Method 1
The variable displacement pump's basic operation is similar to other reciprocating plunger pumps in that it employs a crankshaft with a connecting rod. The connecting rod is connected to a crosshead to which the pump plunger is attached. The big difference in the present invention over other reciprocating well service plunger pumps is that the amount of offset of the crank in the present invention is variable
Data Source
AI summary
A variable displacement reciprocating pump with pumping rate that is adjustable from zero to maximum stroke while the pump is running. Stroke is varied by changing relative position of pairs of eccentric inner and outer cams that drive the pump's plungers. The pump's input drive shaft drives two gear trains: a first gear train that turns the inner cams and a second gear train that turns the outer cams. These cams normally revolve together with no relative motion occurring between them. A rotary actuator is positioned in the first gear train to rotate the inner cams relative to the outer cams and thereby changes the pump's stroke. A computerized system of sensors and control valves allows the pump to be automatically controlled or limited to any one or combination of desired output flow, pressure and horsepower.