Pressure-Responsive Minimum Stops in Variable Displacement Pumps
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Solution Overview
Problem
Conventional variable displacement pumps face challenges in maintaining mechanical efficiency and temperature control at minimum flows, necessitating improved systems and methods for variable minimum flow stops.
Innovation Solution
A system incorporating a pressure sensing valve (PSV) and an electrohydraulic servo valve (EHSV) to adjust the minimum displacement of the variable displacement mechanism based on pressure differentials, using a piston rod and biasing member to vary the stop position, and a position sensor for feedback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a fixed minimum stop is used in variable displacement pumps, then the pump mechanism temperature is controlled at maximum operational pressures, but the mechanical efficiency is reduced at lower pressure differentials due to excessive minimum displacement
Solution Approach 1:
The patent applies dynamics by making the minimum displacement stop variable rather than fixed. The stop position is dynamically adjusted based on the pressure differential across the pump, allowing the system to adapt to different operating conditions. This resolves the contradiction by enabling the pump to maintain adequate flow for temperature control at high pressures while reducing minimum displacement to minimize parasitic energy loss at lower pressures.
Solution Approach 2:
The patent changes the parameter of minimum displacement based on the pressure differential parameter. By linking the stop position to the pressure differential, the system automatically adjusts the minimum displacement parameter according to operating conditions. This allows optimization of both temperature control and energy efficiency across different pressure regimes.
2Loss of energy
If a variable stop is used to adjust minimum displacement based on pressure differential, then parasitic energy loss is reduced, but the device complexity increases due to additional pressure sensing and actuation mechanisms
Solution Approach 1:
The patent applies self-service by designing a system where the pressure differential automatically actuates the stop adjustment mechanism. The pressure differential itself provides the actuating force through the pressure sensing valve, eliminating the need for external sensors, controllers, or power sources. This reduces device complexity while achieving variable minimum displacement to minimize parasitic energy loss.
Solution Approach 2:
The patent uses pneumatic/hydraulic principles by employing a pressure sensing valve that utilizes the pressure differential across the pump to directly actuate the stop mechanism. The fluid pressure itself serves as the control signal and actuating force, simplifying the system compared to electronic control while achieving the desired variable displacement control.
3Loss of energy
If the minimum displacement is reduced at lower pressure differentials, then the flow rate decreases, but the mechanical efficiency is improved by matching flow to actual system needs
Solution Approach 1:
The patent applies dynamics by making the minimum displacement variable rather than fixed. The stop position is dynamically adjusted based on the pressure differential across the pump, allowing the system to adapt to different operating conditions. This resolves the contradiction by enabling the pump to maintain adequate flow for temperature control at high pressures while reducing minimum displacement to minimize parasitic energy loss at lower pressures.
Solution Approach 2:
The patent changes the parameter of minimum displacement based on the pressure differential parameter. By linking the stop position to the pressure differential, the system automatically adjusts the minimum displacement parameter according to operating conditions. This allows optimization of both temperature control and energy efficiency across different pressure regimes.
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
Enables dynamic adjustment of minimum displacement to optimize flow rates, reducing parasitic energy loss and maintaining mechanical efficiency across varying pressure conditions.
Implementation Method 1
A pressure sensing valve (PSV) is operatively connected between the inlet line and the outlet line to actuate a stop member to adjust stopping position of the variable stop based on pressure differential between the inlet line and the outlet line
Implementation Method 2
A biasing member can be operatively connected between the PSV housing and the valve member to bias the valve member in a first direction
Data Source
AI summary
A system includes a variable displacement pump (VDP) in fluid communication with an inlet line and with an outlet line. The VDP includes a variable displacement mechanism configured to vary pressure to the outlet line. The VDP includes a variable stop configured to vary minimum displacement of the variable displacement mechanism based on position of the variable stop relative to a housing of the VDP. A pressure sensing valve (PSV) is operatively connected between the inlet line and the outlet line to actuate a stop member to adjust stopping position of the variable stop based on pressure differential between the inlet line and the outlet line.