Variable Displacement Pump Control Across Turndown Pressure Ranges
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Solution Overview
Problem
Conventional variable displacement pumps face inefficiencies due to high turn-down ratios, necessitating a tradeoff between operating range and efficiency.
Innovation Solution
A system with a controller that switches between variable and fixed displacement modes, utilizing a pressure regulating valve and electrohydraulic servo valve to optimize pump operation, allowing for high turndown ratios and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable displacement pump is designed for high turn-down ratio, then the operating range is extended, but pump efficiency deteriorates throughout the operating range
Solution Approach 1:
The pump operation is segmented into two distinct modes: variable displacement mode for high pressure operation and fixed displacement mode for low pressure operation. This segmentation allows each mode to be optimized for its specific operating range, with the variable displacement mechanism optimized for high efficiency at high pressures and the fixed displacement mechanism optimized for maintaining efficiency at low pressures, thereby resolving the efficiency deterioration across the full turn-down range
Solution Approach 2:
The system dynamically switches between variable and fixed displacement modes based on operating conditions, specifically transitioning from variable displacement at high pressures to fixed displacement at low pressures. This dynamic adaptation allows the pump to maintain optimal efficiency across the entire operating range while achieving high turn-down ratio, as the displacement control mode is adjusted in real-time based on system pressure feedback
2Manufacturing precision
If variable displacement mechanism is actively controlled, then displacement precision is improved, but device complexity increases
Solution Approach 1:
A transfer valve is introduced as an intermediary component that automatically routes the control pressure to either the variable displacement mechanism or the pressure regulating valve based on system pressure conditions. This intermediary simplifies the overall control architecture by eliminating the need for complex electronic control systems, sensors, and actuators, while still achieving precise displacement control through passive pressure-based switching and regulation
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
The system achieves reduced turn-down ratios and increased pump efficiency by adjusting displacement modes based on pressure ranges, enhancing performance across varying operational conditions.
Implementation Method 1
an electrohydraulic servo valve (EHSV) that connects to the pump control line in the first mode
Implementation Method 2
a pressure regulating valve (PRV) operatively connected to the pump inlet and to the pump outlet to control recirculation from the pump outlet to the pump inlet
Data Source
Figure 1
Figure 2
AI summary
A system includes a variable displacement pump (VDP) (102) having a pump inlet (104), a pump outlet (106), and a pump control line (108) configured to receive a control pressure to actuate a variable displacement mechanism (110) of the VDP. A controller (112) is operatively connected to the pump control line to actively control actuation of the variable displacement mechanism in a first mode for variable displacement pumping and in a second mode for fixed displacement pumping.