Aircraft Cabin Blower Startup Using Reversible Variator Control
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Solution Overview
Problem
Cabin blower systems in aircraft face contamination issues due to oil and other lubricants, and contactless bearings can lead to increased wear during start-up due to insufficient clearance at low operating speeds.
Innovation Solution
Aircraft cabin blower systems with a contactless bearing arrangement and a reversible variator that controls the speed and direction of rotation, using reverse operation to hold the compressor stationary until it reaches the lift-off speed, reducing wear and eliminating the need for lubricants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If contactless bearings are used in the cabin blower compressor, then contamination with oil and lubricants is eliminated, but wear on the bearings increases during start-up due to insufficient clearance at low operating speeds
Solution Approach 1:
The system performs a preliminary reverse rotation action before normal operation to prepare the contactless bearings for safe operation. During start-up, the variator drives the compressor in reverse direction to build sufficient clearance between bearing surfaces before transitioning to forward rotation, preventing wear while maintaining the contamination-free benefit of contactless bearings
Solution Approach 2:
The system uses reverse rotation as a preparatory step before normal forward operation. By rotating the compressor in reverse during start-up, the system creates the necessary clearance conditions that would otherwise be insufficient at low speeds, thereby protecting the contactless bearings from wear while maintaining their contamination-free operation
2Productivity
If the cabin blower compressor is accelerated directly to operating speed, then productivity is improved, but wear on contactless bearings increases due to insufficient clearance at low speeds
Solution Approach 1:
Before accelerating the compressor to operating speed, the system performs a preliminary reverse rotation phase that builds sufficient clearance between bearing surfaces. This preliminary action ensures that when forward acceleration occurs, the bearings are protected from wear, allowing rapid acceleration to operating speed without compromising reliability
Solution Approach 2:
The start-up sequence uses periodic action by alternating between reverse rotation (to build clearance) and forward acceleration (to reach operating speed). This periodic sequence of reverse then forward rotation ensures bearing protection while maintaining efficient productivity, as the compressor reaches full operating speed after the brief preparatory reverse phase
Data Source
AI summary
Aircraft cabin blower systems and methods of operating aircraft cabin blower systems are provided. One aircraft cabin blower system comprises: a cabin blower compressor having a contactless bearing arrangement; a transmission having a transmission output arranged to drive the cabin blower compressor, a first transmission input arranged to receive mechanical power from a gas turbine engine, and a second transmission input; a reversible variator arranged to receive power from the gas turbine engine and to output mechanical power to the second transmission input, the reversible variator operable to output in both forward and reverse directions of rotation; and a controller configured to control an output speed and direction of rotation of the reversible variator.