Two-Ball Check Valve Assembly for RAT Re-Stow Pump Pressure Staging

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Solution Overview

Problem

Current check valve designs for RAT re-stow pump assemblies are complex and expensive, necessitating a simpler and less costly solution to manage pressure and facilitate efficient re-stowing of ram air turbines.

Innovation Solution

A check valve assembly with a valve body featuring a first and second end, an actuator port, and a fluid inlet, utilizing two balls and a spring to control fluid flow through different stages of operation, thereby managing pressure and preventing over-pressurization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two separate check valves are used to perform different stages of operation, then pressure control reliability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvepressure control reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines two separate check valves into a single integrated check valve assembly that performs both stages of pressure control. The assembly includes a valve body with a first check valve for initial pressure relief and a second check valve for secondary pressure control, both housed within one unit. This merging reduces the number of separate components while maintaining the reliability of dual-stage pressure control.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single check valve assembly is designed to perform multiple functions: it provides both first-stage and second-stage pressure control, houses two separate check valves with different set pressures, and includes integrated mounting features. This multi-functional design eliminates the need for two separate check valve components while achieving the same pressure control objectives.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If two separate check valves are used to perform different stages of operation, then pressure control reliability is improved, but manufacturing cost increases

Engineering Contradiction:
Improvepressure control reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines two separate check valves into a single integrated check valve assembly that performs both stages of pressure control. The assembly includes a valve body with a first check valve for initial pressure relief and a second check valve for secondary pressure control, both housed within one unit. This merging reduces the number of separate components while maintaining the reliability of dual-stage pressure control.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If traditional check valve designs are used, then pressure control function is achieved, but installation complexity and cost increase

Engineering Contradiction:
Improvepressure control functionVSAvoidinstallation ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent combines two separate check valves into a single integrated check valve assembly that performs both stages of pressure control. The assembly includes a valve body with a first check valve for initial pressure relief and a second check valve for secondary pressure control, both housed within one unit. This merging reduces the number of separate components while maintaining the reliability of dual-stage pressure control.

Inventive Principle:
Principle #5Merging (Combining)

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

The check valve assembly effectively manages pressure differentials to control fluid flow, preventing over-pressurization and enabling efficient re-stowing of RATs while being simpler and less expensive to manufacture and install.

Implementation Method 1

a check valve spring provided in spring force engagement with the second ball, the check valve spring being sized and positioned to bias the second ball towards the second end

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a first stage pressure differential between the actuator port and the fluid inlet creates a fluid flow path from the inlet to the actuator port by causing the second ball to press against the bias of the check valve spring

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentEP4538567A1Check valve for ram air turbine re-stow pump
Publication Date: 2025.04.16 HAMILTON SUNDSTRAND CORP
  • EP4538567A1 patent drawingFigure 1~2
  • EP4538567A1 patent drawingFigure 3A~3B
  • EP4538567A1 patent drawingFigure 4~5

AI summary

A check valve assembly comprising a valve body having a first end and a second end, the valve body extending along an axis from the first end to the second end; a check valve outlet (30) is located between the first and the second end; an actuator port (32) provided in the check valve body at a location axially between the outlet (30) and the second end, for fluid connection, in use, to a pump actuator (22), the valve body further comprising a fluid inlet (25) via which the check valve is, in use, connected to a fluid tank (10), the fluid inlet (25) being provided in the valve body towards the second end, axially between the actuator port (32) and the second end; the assembly further comprising check valve components located in the check valve body configured to control the flow of fluid entering the check valve from the tank via the fluid inlet (25), and leaving the check valve via the outlet, according to the first and second stages of operation, the check valve components comprising a first ball (202) located in the valve body adjacent the first end, and a second ball (204) located in the valve body adjacent the second end, and a check valve spring (206) provided in spring force engagement with the second ball (204), the check valve spring being sized and positioned to bias the second ball towards the second end; wherein a first stage pressure differential between the actuator port (32) and the fluid inlet (25) creates a fluid flow path from the inlet to the actuator port by causing the second ball to press against the bias of the check valve spring to create a flow passage between the second ball and the second end, and causing the first ball to block the flow of fluid to the outlet (30), and wherein removal of the first stage pressure differential causes the check valve spring to return the second ball to its biased position to close the passage from the fluid inlet to the actuator port and to cause the first ball to move to open a fluid passage between the actuator port and the outlet.