Variable Displacement Pump Direct Actuation Control

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Solution Overview

Problem

Conventional variable displacement pumps, such as those used in aircraft fuel systems, have complex hydraulic controls that result in lag between input and output and reliability issues, necessitating an improvement in control precision and simplicity.

Innovation Solution

A variable displacement pump design incorporating a rotor with vanes, a cam ring, and a retainer, along with a direct actuation mechanism like an electrohydraulic servo valve or a non-hydraulic electromechanical arm assembly, allowing direct control of the pumping action through a controller, which reduces complexity and enhances reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If complex hydraulic controls are used in variable displacement pumps, then the pumping action can be controlled, but lag between input and output occurs and reliability deteriorates

Engineering Contradiction:

ImprovereliabilityVSAvoidcomplex hydraulic controls

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex hydraulic control system from the variable displacement pump, replacing it with a direct actuation mechanism. The retainer is directly actuated by an electromechanical arm assembly or electrohydraulic servo valve, removing the intermediate hydraulic control components that caused lag and reliability issues.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the traditional hydraulic control system with an electromechanical arm assembly or electrohydraulic servo valve. This substitution eliminates the complex hydraulic control circuitry and replaces it with a more reliable electromechanical direct actuation system that reduces lag between control input and pump output.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of time

If complex hydraulic controls are used in variable displacement pumps, then the pumping action can be controlled, but lag between input and output occurs

Engineering Contradiction:

Improvelag between input and outputVSAvoidcomplex hydraulic controls

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent removes the intermediate hydraulic control components that cause time lag, implementing direct actuation of the retainer by an electromechanical arm assembly or electrohydraulic servo valve. This extraction of unnecessary components eliminates the lag between control input and pump output.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the slow hydraulic control system with a faster electromechanical arm assembly or electrohydraulic servo valve. This replacement significantly reduces the time lag between control signal and actual pump displacement change, improving response time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If direct actuation mechanism is used to control retainer position, then control precision and response speed improve, but device complexity may increase

Engineering Contradiction:

Improvecontrol precisionVSAvoiddirect actuation mechanism

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the control parameter from indirect hydraulic pressure control to direct electromechanical position control. The electromechanical arm assembly or electrohydraulic servo valve provides precise control of the retainer position through direct actuation, improving measurement and control precision while maintaining manageable device complexity.

Inventive Principle:

Principle #35Parameter changes

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 design enables direct and precise control of the pumping action, reducing lag and improving reliability by eliminating the need for complex hydraulic controls, allowing for faster displacement changes and more efficient engine control over fuel flow.

Implementation Method 1

the direct actuation mechanism can be an electrohydraulic servo valve (EHSV) in direct hydraulic communication with the retainer via a hydraulic piston

Methodology Applied

Scientific EffectElectrohydraulic conversion:

Implementation Method 2

an electrohydraulic servo valve (EHSV) in direct hydraulic communication with the retainer via a hydraulic piston

Methodology Applied

Scientific EffectHydraulic actuation: Hydraulic Press

Implementation Method 3

a biasing member configured to provide an opposing force to a direction of force applied by the direct actuation mechanism to bias the retainer in a bias direction

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP4123177A1Variable displacement pump systems with direct actuation

Publication Date: 2023.01.25 HAMILTON SUNDSTRAND CORP

Figure 1A
Figure 1B
Figure 2A

AI summary

A variable displacement pump can include a rotor (101) having a plurality of vanes (103), a cam ring (105) surrounding the rotor and vanes, the vanes configured to extend from the rotor and contact an inner cam surface (105a) of the cam ring, and a retainer (107) configured to contact the cam ring and to move the cam ring relative to the rotor to modify a pumping action. The pump can also include a direct actuation mechanism (109) configured to control a position of the retainer to control a position of the cam ring and the pumping action.