Variable Displacement Pump Mode Switching for Higher Cruise Efficiency

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Solution Overview

Problem

Variable displacement pumps in fuel delivery systems face inefficiencies due to high turn-down ratios, requiring a trade-off between operating range and efficiency, with conventional designs often resulting in suboptimal performance.

Innovation Solution

A system with a controller that actively switches between variable and fixed displacement modes, utilizing a pressure regulating valve, electrohydraulic servo valve, and transfer valve to manage flow and pressure, allowing for efficient operation across a wide range of conditions by adjusting displacement mechanisms based on sensor feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a variable displacement pump is designed for high turn-down ratio, then the operating range is improved, but pump efficiency deteriorates

Engineering Contradiction:

Improveturn-down ratioVSAvoidpump efficiency

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The pump operation is segmented into two distinct modes: variable displacement mode for high flow demands and fixed displacement mode for low flow demands. This segmentation allows each mode to operate optimally within its designated range, avoiding the efficiency penalties of designing for the entire wide range. The controller automatically switches between modes based on demand conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between variable and fixed displacement modes based on real-time operating conditions. The controller monitors flow demand and actively transitions the pump between operational states, allowing the displacement mechanism to be variable when needed and fixed when optimal for efficiency. This dynamic adaptation resolves the contradiction by not requiring a static design compromise.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If a variable displacement mechanism is actively controlled, then displacement precision is improved, but device complexity increases

Engineering Contradiction:

Improvedisplacement control precisionVSAvoidcontrol system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

An electrohydraulic servo valve acts as an intermediary between the electrical control signal and the hydraulic displacement mechanism. This intermediary component translates electrical commands into precise hydraulic actuation, enabling accurate displacement control without requiring complex direct mechanical control systems. The servo valve handles the complexity of precise control, simplifying the overall system architecture.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The control system replaces complex mechanical displacement control mechanisms with an electrohydraulic approach. Instead of using intricate mechanical linkages and positioners, the system uses electrical signals through the servo valve to control hydraulic pressure, which in turn controls the displacement mechanism. This substitution reduces mechanical complexity while maintaining or improving control precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach reduces the turn-down ratio, increases pump efficiency, and minimizes temperature rise by optimizing displacement settings, particularly at cruise power settings, while maintaining high turndown ratios, especially in aircraft fuel systems.

Implementation Method 1

an electrohydraulic servo valve (EHSV) that connects to the pump control line in the first mode

Methodology Applied

Scientific EffectElectrohydraulic conversion:

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

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 3

The PRV can include a piston configured to move against a bias based on a difference in pressure between the control line of the PRV and a first connection line to the pump outlet

Methodology Applied

Scientific EffectPressure difference: Pressure Gradient

Data Source

PatentUS20240183352A1Variable displacement pumps with fixed and active displacement control modes

Publication Date: 2024.06.06 HAMILTON SUNDSTRAND CORP

AI summary

A system includes a variable displacement pump (VDP) having a pump inlet, a pump outlet, and a pump control line configured to receive a control pressure to actuate a variable displacement mechanism of the VDP. A controller 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.