Variable-Speed Lubrication Pump Control for Aircraft Engines
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Solution Overview
Problem
Aircraft gas turbine engine lubrication systems often rely on oversized pumps and piping due to design conditions, leading to unnecessary energy dissipation and excess lubricant supply, which increases system size and weight, and does not account for varying engine load, speed, temperature, and altitude conditions effectively.
Innovation Solution
A system and method that uses a motor and pump assembly with a motor control unit to precisely control lubricant supply flow based on lubricant temperature, rotational speed, and aircraft operating conditions, allowing for variable-speed operation to maintain optimal lubricant pressure, thereby avoiding the need for oversized components and reducing energy wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supply pump is designed to supply design intent flow at maximum aircraft altitude and highest expected lubricant temperature, then the pump can meet the most unfavorable operating condition, but the pump becomes oversized and causes excess lubricant flow under normal conditions
Solution Approach 1:
The pump system transitions from fixed-speed to variable-speed operation, allowing the pump to dynamically adjust its rotational speed based on real-time operating conditions such as engine load, temperature, and altitude. This enables the pump to deliver the exact required lubricant flow rate rather than operating at constant high speed, eliminating excess flow while maintaining reliability under varying conditions
Solution Approach 2:
The system incorporates feedback control mechanisms that continuously monitor operating parameters (engine speed, load, temperature) and adjust pump speed accordingly. This closed-loop control ensures the pump delivers optimal lubricant flow rates matched to actual engine needs, preventing both deficiency and excess flow conditions
2Reliability
If the supply pump is oversized to meet maximum operating conditions, then the pump can handle all operating scenarios, but the system piping circuit must also be oversized increasing system size and weight
Solution Approach 1:
By implementing variable-speed pump operation, the system can use appropriately sized piping components rather than oversized ones. The dynamic adjustment of pump speed allows the system to operate efficiently with components sized for normal conditions rather than maximum conditions, reducing overall system weight while maintaining capability
3Reliability
If the supply pump is oversized, then the pump can meet design intent flow requirements, but the pump needslessly dissipates energy at many operating conditions
Solution Approach 1:
The variable-speed pump adjusts its rotational speed to match the actual lubricant flow requirements of the engine under different operating conditions. This prevents the pump from operating at high speed when low flow is needed, significantly reducing unnecessary energy dissipation while maintaining the capability to supply design intent flow when required
Solution Approach 2:
The system changes the operational parameters of the pump by varying its speed based on operating conditions. This parameter adjustment ensures the pump operates efficiently across the full range of conditions, converting what would be wasted energy into useful work by matching pump output to actual demand
4Reliability
If the supply pump is oversized, then the pump can deliver design intent flow, but excess lubricant is supplied to and present in the engine
Solution Approach 1:
The variable-speed pump delivers the precise amount of lubricant flow required by the engine based on real-time operating conditions. This dynamic flow control prevents excess lubricant from being supplied to the engine, eliminating the need for recycle control systems while maintaining reliable lubrication
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 approach allows for more precise and efficient lubricant supply, reducing system size, weight, and energy dissipation, while ensuring optimal lubrication across varying operating conditions without excess lubricant flow.
Implementation Method 1
a motor (106) coupled to receive motor speed commands representative of a commanded motor speed and operable, in response thereto, to rotate at the commanded motor speed and supply a drive force
Implementation Method 2
a pump having a fluid inlet adapted to couple to a lubricant source and a fluid outlet and coupled to receive the drive force from the motor and configured, in response thereto, to draw lubricant from the lubricant source into the fluid inlet and supply lubricant, via the fluid outlet, to a rotating machine
Data Source
AI summary
A system and method for precisely controlling lubricant supply flow to one or more rotating machines in an aircraft includes a motor, a pump, and a motor control unit. The motor is coupled to receive motor speed commands and, in response to the commands, rotates at the commanded motor speed and supplies a drive force to the pump. The pump, upon receipt of the drive force, draws lubricant from a lubricant source and supplies it to a rotating machine. The motor control unit determines a scheduled lubricant supply pressure based at least in part on lubricant temperature, rotating machine rotational speed, and one or more aircraft operating conditions, and to supplies the motor speed commands to the motor that cause the pump to supply lubricant at the scheduled lubricant supply pressure.