Variable Displacement Pump Flow Splitting for Dual Pressure Schedules
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Solution Overview
Problem
Legacy fuel delivery systems in aerospace applications, particularly those using centrifugal pumps, face challenges with the larger envelope size of variable displacement pumps (VDPs) compared to centrifugal or fixed displacement pumps, necessitating improved systems and methods for efficient fuel control and hydraulic systems.
Innovation Solution
A variable displacement pump system with a pressure sensor and controller that splits flow into two branches with different pressure schedules, utilizing an electrohydraulic servo valve and throttling metering system to regulate pressures and control the displacement mechanism, allowing for efficient supply to both hydraulic actuation and gas generating systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If variable displacement pumps are used to replace centrifugal or fixed displacement pumps, then fuel control precision and pressure regulation capability are improved, but the envelope size increases
Solution Approach 1:
The patent integrates multiple functions into a nested configuration where the variable displacement pump mechanism is housed within a compact structure that shares space with the drive system and control components. The piston pump elements are arranged in a nested fashion within the pump housing, allowing the displacement mechanism to be contained within the overall pump envelope rather than requiring separate housings for each functional element.
Solution Approach 2:
The patent combines the variable displacement pump with the drive system and control mechanisms into a single integrated assembly. The electrohydraulic control system is merged with the pump structure, and the drive shaft is directly coupled to the pump elements, eliminating the need for separate gearbox assemblies and reducing the overall envelope size while maintaining precise pressure regulation capability.
2Quantity of substance
If a single pump supplies both hydraulic actuation system and gas generating system, then the number of pumps is reduced, but the pressure regulation complexity increases
Solution Approach 1:
The patent employs a variable displacement piston pump with an electrohydraulic control system that dynamically adjusts the pump output pressure and flow rate in real-time. The controller receives pressure feedback from sensors in both the hydraulic actuation system and gas generating system, and automatically modulates the pump displacement to maintain the required pressure schedules for both systems simultaneously, eliminating the need for multiple fixed-displacement pumps.
Solution Approach 2:
The patent changes the operating parameters of the pump by varying its displacement volume and output pressure according to the instantaneous demands of the two different systems. The electrohydraulic control system continuously adjusts the pump delivery pressure to match the different pressure schedules required by the hydraulic actuation system and gas generating system, allowing a single pump to replace multiple pumps with fixed operating parameters.
3Adaptability or versatility
If pressure reduction is achieved through throttling metering system, then dual-pressure supply capability is enabled, but the component count increases
Solution Approach 1:
The patent designs the output splitter as a multi-functional component that not only divides the pump output into two separate lines for the hydraulic actuation system and gas generating system but also incorporates pressure regulation capabilities within the splitter structure. The splitter includes integrated flow control elements and pressure sensing ports that allow it to perform multiple functions (flow distribution, pressure monitoring, and pressure regulation) in a single component, reducing the overall component count.
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 the envelope size and number of components required, enabling efficient dual-pressure fuel supply to different systems, such as actuation and gas generation, while maintaining precise pressure control and reducing the number of gearbox drive pads and pump count.
Implementation Method 1
A pressure sensor is operatively connected to the pump outlet to generate feedback indicative of the second pressure
Implementation Method 2
An electrohydraulic servo valve (EHSV) can include a first connection to the pump inlet, a second connection to the pump outlet, and a pump control line operatively connected to actuate the variable displacement mechanism
Implementation Method 3
The throttling metering system can include a metering valve (MV) connected to the second outlet branch to step down pressure from the pump outlet down to a third pressure below the second pressure
Implementation Method 4
The VDP is configured to receive a flow at the pump inlet at a first pressure and to outlet a flow from the pump outlet at a second pressure elevated relative to the first pressure
Data Source
AI summary
A system includes a variable displacement pump (VDP) with a pump inlet and a pump outlet. The VDP is configured to receive a flow at the pump inlet at a first pressure and to outlet a flow from the pump outlet at a second pressure elevated relative to the first pressure. The VDP includes a variable displacement mechanism configured to vary the second pressure. A controller is operatively connected to a pressure sensor and to the variable displacement mechanism for control of the VDP. An output splitter is configured to split flow from the pump outlet to a first outlet branch and to a second outlet branch for supplying two different systems each having a different pressure schedule. The output splitter is operatively connected to the controller, which is configured to control the output splitter to regulate pressure in both of the first and second outlet branches.