Dual-Function HPRV-PRV Valve for Direct-Control Variable Displacement Pumps
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Solution Overview
Problem
Variable displacement pumps in aircraft fuel systems face challenges in maintaining responsiveness and consistent pressure during rapid hydraulic pressure adjustments, particularly during actuation transients, affecting aircraft performance and safety.
Innovation Solution
A direct control variable displacement pump (VDP) integrated with a dual-function high-pressure relief valve (HPRV)-pressure regulating valve (PRV) that dynamically adjusts between PRV and HPRV modes to maintain steady-state bypass flow, dampen pressure droops, and reduce spikes, using a combined PRV spool and HPRV piston mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a variable displacement pump is used to reduce recirculated fuel flow, then fuel system efficiency is improved, but responsiveness during rapid hydraulic pressure adjustments deteriorates
Solution Approach 1:
The relief valve is divided into two functional modes: pressure regulating valve (PRV) mode for steady-state operation and high-pressure relief valve (HPRV) mode for transient response. The PRV spool and HPRV piston work in sequence to provide both energy efficiency during normal operation and rapid response during transients, resolving the contradiction between fuel efficiency and responsiveness.
Solution Approach 2:
The system dynamically transitions between PRV and HPRV modes based on operating conditions. During steady-state, the PRV maintains bypass flow for efficiency. During actuation transients, the HPRV rapidly opens to provide immediate pressure relief, enabling the system to adapt its response characteristics to match operational requirements.
2Loss of energy
If a variable displacement pump is used to reduce recirculated fuel flow, then fuel system efficiency is improved, but pressure consistency during actuation transients deteriorates
Solution Approach 1:
The HPRV is pre-positioned and spring-loaded to provide immediate pressure relief capability during transients. The spring forces (HPRV spring and PRV spring) are configured to ensure the HPRV piston can rapidly respond to pressure spikes, cushioning the impact of actuation transients before they affect system stability.
Solution Approach 2:
The HPRV piston acts as an intermediary mechanism between the PRV spool and the bypass flow path. When the PRV spool moves during transients, it applies force to the HPRV piston, which then rapidly opens the front entry relief flow path to stabilize pressure, mediating the transition between steady-state and transient conditions.
3Speed
If a dual-function HPRV-PRV valve is used to improve responsiveness, then device complexity increases
Solution Approach 1:
The PRV and HPRV functions are merged into a single integrated valve assembly. The PRV spool and HPRV piston share a common housing, fluid pathways, and control logic, allowing dual functionality to be achieved without the complexity of two separate valve systems. The combined structure reduces component count and simplifies installation while maintaining both steady-state regulation and transient response capabilities.
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
Enhances responsiveness and pressure regulation during transient events, ensuring consistent fuel pressure and improved aircraft performance by effectively managing pressure fluctuations.
Implementation Method 1
The dual-function HPRV-PRV regulating valve further comprises an HPRV spring and a PRV spring. The HPRV spring has a first end coupled to the housing and an opposing end coupled to a first side of the HPRV stop surface. The PRV spring has a first end coupled to a second side of the HPRV stop surface opposite the first side and a second end coupled to the PRV spool.
Implementation Method 2
The HPRV piston is slidably disposed against an inner diameter surface of the valve sleeve.
Data Source
AI summary
A dual-function high-pressure relief valve pressure regulating valve includes valve sleeve, a spool that slides laterally in a first direction and a second direction, and a piston disposed against the valve sleeve. The valve sleeve includes a PRV inlet window, a PRV outlet window, and a pressure relief outlet window. The spool includes a PRV inlet landing, and a combined PRV/HPRV landing. The piston is configured to slide laterally in the first direction and the second direction based on a pressing force applied by the spool. The dual-function HPRV-PRV operates in a first mode to adjust the spool and maintain opening of the PRV inlet window and the PRV outlet window while closing the pressure relief outlet window, and operates in a second mode to adjust both the spool and the piston to open each of the PRV inlet window, the PRV outlet window, and the pressure relief outlet window.