Generator Coolant Pressure Relief Valve With Active Flow Control
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Solution Overview
Problem
Conventional pressure regulating valves in aircraft generator cooling systems are inefficient due to passive control, leading to excessive flow at high speeds and potential pressure pulsations, which can damage the oil circuit and increase machine windage and pump losses.
Innovation Solution
An active pressure relief valve system controlled by a generator control unit (GCU) that regulates coolant flow based on inputs from the cooling system and generator, including pressure, temperature, and rotation frequency, using a lookup table to determine optimal valve output, thereby recirculating coolant back to the pump inlet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a passive pressure regulating valve with spring mass system is used to regulate system pressure, then the system can limit pressure, but pressure pulsations occur that can damage the oil circuit
Solution Approach 1:
The patent replaces the mechanical spring-mass system with an electronic control system that uses a sensor to detect pressure and a controller to actuate the pressure relief valve. This substitution eliminates the inherent pulsations of mechanical springs while maintaining pressure regulation functionality.
Solution Approach 2:
The patent implements a feedback control system where a sensor continuously monitors pressure in the cooling system and feeds this information to a controller. The controller adjusts the pressure relief valve position based on the feedback signal, maintaining stable pressure without the pulsations characteristic of passive spring-based systems.
2Temperature
If the pressure regulating valve and pump system is sized to provide proper cooling at low speed, then adequate cooling flow is ensured, but a large amount of flow occurs at high speed causing inefficiency
Solution Approach 1:
The patent transitions from a static, passively controlled system to a dynamically controlled system. The electronic controller continuously adjusts the pressure relief valve position based on real-time pressure and temperature feedback, enabling the system to optimize coolant flow at varying generator speeds and eliminate the inefficiencies of oversized flow at high speeds.
Solution Approach 2:
The patent changes the control parameter from a fixed mechanical spring setting to a variable electronic control signal that can be dynamically adjusted. This allows the pressure relief valve to modulate its opening position continuously, optimizing the balance between cooling effectiveness and energy efficiency across the full operating range.
3Productivity
If a variable speed pump is used to provide cooling, then cooling flow can be adjusted, but passive control requires the system to be oversized to handle high speed conditions
Solution Approach 1:
The patent uses feedback from pressure and temperature sensors to dynamically control the pressure relief valve, eliminating the need for oversized passive components. The active control system adjusts flow in real-time, allowing the pump and valve to be sized for optimal performance rather than maximum capacity.
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 solution optimizes coolant flow efficiency across varying generator speeds, reduces windage losses, and eliminates pressure pulsations, allowing for tighter control of oil spray and higher current densities without additional system complexity.
Implementation Method 1
actuating the pressure relief valve based on input from the cooling system and/or from the generator... actuating the pressure relief valve based on pressure of coolant in the cooling system
Implementation Method 2
determining an output of the pressure relief valve from a look up table (LUT) correlating input from the cooling system and/or from the generator to the output of the pressure relief valve
Data Source
Figure 1
Figure 2
AI summary
A method includes pumping coolant into a cooling system (118) of a generator while the generator is generating electrical power. The method includes regulating flow into the cooling system (118) using a pressure relief valve (134) to recirculate a portion of the coolant back to an inlet of the pump (120). Using the pressure relief valve (134) includes actuating the pressure relief valve based on input from the cooling system (118) and/or from the generator.