Brushless Motor Pump with Recirculation Cooling for Aero-Engine Fuel
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Solution Overview
Problem
Aero-engine fuel pumping units face challenges in operating reliably with multi-phase flows due to air dissolution in fuel at varying altitudes, requiring the low-pressure pump to provide adequate pressure rise independently of the wing tank pumps and handle mixed fuel states effectively.
Innovation Solution
The low-pressure pump is driven by an electrical motor, allowing independent speed control from the engine's running speed, with recirculation flow cooling the motor and eliminating the need for a rotor ring seal, enabling compact integration and enhanced motor cooling. Additionally, a variable frequency motor drive measures electrical power to detect and compensate for multi-phase flows by adjusting speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the LP pump is driven at fixed speed relationship with engine running speed, then the pump structure is simple, but the pump cannot provide adequate pressure rise with multi-phase flow
Solution Approach 1:
The patent applies dynamics by enabling the LP pump to operate at variable speeds independent of engine running speed through an electrical motor drive. This allows the pump to increase speed when multi-phase flow is detected, providing adequate pressure rise without requiring a more complex fixed-speed mechanical drive system.
2Stress or pressure
If the LP pump size is increased to provide required pressure rise with multi-phase flow, then the pressure rise is adequate, but the overall pump size becomes larger
Solution Approach 1:
The patent applies parameter changes by varying the operating speed of the LP pump through electrical motor control. Instead of increasing pump size, the system changes the speed parameter to provide adequate pressure rise with multi-phase flow, maintaining a compact pump design.
3Device complexity
If the motor is not cooled by recirculation flow, then the seal structure is simpler, but the motor cannot operate at higher power
Solution Approach 1:
The patent applies multi-functionality by using the recirculation flow to serve dual purposes: cooling the electrical motor and providing adequate lubrication. This eliminates the need for separate sealing structures while enabling the motor to operate at higher power levels.
4Stability of the object's composition
If the pump runs at higher speed to force air back into solution, then homogeneous fuel delivery is achieved, but the risk of electrical breakdown in motor windings increases
Solution Approach 1:
The patent applies the intermediary principle by using recirculation flow as a mediator that cools the motor windings and prevents electrical breakdown. This allows the pump to run at higher speeds for homogeneous fuel delivery while the recirculation flow protects against electrical failures.
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 allows the low-pressure pump to efficiently handle multi-phase flows by increasing speed to ensure homogeneous fuel delivery to the high-pressure pump, reducing the risk of electrical breakdown and enabling smaller pump designs, while also monitoring fuel tank conditions.
Implementation Method 1
the recirculation flow cools the electrical motor
Implementation Method 2
a portion of the raised pressure fluid flow is allowed to recirculate back towards the inlet through the electrical motor, thus cooling the motor
Implementation Method 3
The pump has a centrifugal impeller driven by a brushless electrical motor
Implementation Method 4
to provide a required pressure rise to deal with multi-phase flow, the LP pump can simply be run at a higher speed
Implementation Method 5
The pump has a centrifugal impeller driven by a brushless electrical motor
Implementation Method 6
Increasing the inlet pressure to the HP pump forces any undissolved air back into solution
Data Source
Figure 1~2
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Figure 5~6
AI summary
A pump has a brushless electrical motor including a stator assembly and a rotor ring arranged externally of the stator assembly. The pump further has a centrifugal impeller operatively connected to the rotor ring such that the electrical motor rotates the impeller. The impeller is configured to raise the pressure of a fluid which flows through the impeller between an inlet and an outlet thereof. The pump is configured such that a portion of the raised pressure fluid flow is diverted to form a recirculation flow which circulates through and cools the electrical motor before being returned to the impeller for re-pressurisation thereby.