Fuel Pump Selector Valve for Backup Pump Testing
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Solution Overview
Problem
Existing fuel delivery systems in aerospace face challenges in selecting and testing secondary pumps to back up primary pumps, particularly at engine start, where latent failures need to be identified to ensure reliable operation.
Innovation Solution
A pump selector system with a controllable valve and selector valve that toggles between positions to block or allow flow from primary or secondary pumps, incorporating a bleed line with an orifice for built-in testing, ensuring only one pump supplies fluid at a time and allowing for functional verification without high pressure relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a secondary pump is added to back up the primary pump, then system reliability is improved, but device complexity increases
Solution Approach 1:
The selector valve merges the primary and secondary pump flows into a single output path, allowing one valve to control both pump selections. The controllable valve combines the functions of pressure regulation and flow direction control in a single component, reducing the overall number of separate control elements needed in the system.
Solution Approach 2:
The controllable valve serves multiple functions: it regulates pressure, controls flow direction, and enables the built-in test function by directing flow through the orifice. The selector valve universally manages both primary and secondary pump selections, making the system more reliable without proportionally increasing complexity.
2Reliability
If built-in testing is implemented to detect latent failures, then reliability is improved, but device complexity increases
Solution Approach 1:
The system performs self-diagnosis through the built-in test function, where the controllable valve directs flow through the orifice to test the secondary pump's operation. This self-testing capability detects latent failures without requiring external testing equipment or procedures, improving reliability while adding minimal complexity.
Solution Approach 2:
The built-in test is performed at engine start before the system enters normal operation, allowing latent failures to be detected in advance. The controllable valve is positioned to direct flow through the orifice during this preliminary test phase, ensuring the secondary pump is verified before critical operation begins.
3Measurement precision
If high pressure relief is used during testing, then testing accuracy is improved, but harmful factors increase
Solution Approach 1:
The orifice serves as an intermediary element that provides a controlled flow path during testing. By directing flow through this calibrated orifice, the system achieves accurate pressure measurement and pump testing without requiring high pressure relief, thereby avoiding the harmful effects of excessive stress on the engine and pump components.
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
Enables reliable pump selection and built-in testing without subjecting primary pumps to high pressure relief, reducing engine stress and maintaining system reliability by ensuring only one pump operates at a time, thus minimizing weight, cost, and parasitic loss.
Implementation Method 1
The controllable valve can include a solenoid valve, where the first state of the controllable valve includes a de-energized state of the solenoid valve and the second state of the controllable valve includes an energized state of the solenoid valve.
Implementation Method 2
The high pressure primary flow is greater than the high pressure secondary flow so as to move the selector valve to block flow from the secondary pump from reaching the fluid destination.
Data Source
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AI summary
In accordance with at least one aspect of this disclosure, a pump selector system can include a primary pump (104) fluidly connected to provide a primary flow to a fluid destination (110), a secondary pump (204) fluidly connected to provide a secondary flow to the fluid destination, and a selector valve (112) disposed downstream of the primary pump and the secondary pump. The selector valve can be configured to toggle between a first position configured to allow flow from the primary pump to flow to the fluid destination and to block flow from the secondary pump to the fluid destination, and a second position configured to allow flow from the secondary pump to flow to the fluid destination and to block flow from the primary pump to the fluid destination.