Counter-Rotating Propeller Drive System Using Segmented Electric Motors

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Solution Overview

Problem

Existing drive systems for counter-rotating parts, such as counter-rotating propellers, require complex gearboxes and are not optimized for use with electric motors, which can increase size, weight, and complexity while compromising efficiency and reliability.

Innovation Solution

A propulsion system where each counter-rotating propeller is driven by its own motor, with a combustion engine and electric motor working together for high power demands and the electric motor or friction brake used to optimize propulsion efficiency and reduce drag, eliminating the need for a complex gearbox.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a single gas turbine engine drives counter-rotating propellers through a gearbox, then the propellers can rotate in opposite directions, but the gearbox becomes complex and increases device complexity

Engineering Contradiction:
Improvecounter-rotating propeller operationVSAvoidgearbox complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The system divides the drive function into separate units: each propeller has its own motor (first motor for first propeller, second motor for second propeller). This segmentation eliminates the need for a complex gearbox while maintaining independent control of each propeller's rotation direction and speed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces the mechanical gearbox system with an electrical drive system. Instead of using mechanical gears to achieve counter-rotation, the invention uses electric motors that can independently control the rotation direction of each propeller through electrical control, thereby eliminating the mechanical complexity of the gearbox.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If a complex gearbox is used to drive counter-rotating propellers, then opposite rotation is achieved, but size and weight increase

Engineering Contradiction:
Improvecounter-rotating propeller operationVSAvoiddrive system weight
Core Design Contradiction:
Ease of operationVSWeight of moving object

Solution Approach 1:

The patent replaces the heavy mechanical gearbox with lightweight electric motors. The electric motors provide the necessary torque and control for counter-rotating propellers without the weight penalty of a complex mechanical transmission system, thereby reducing the overall weight of the drive system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention extracts and removes the gearbox component from the traditional drive system. By taking out the complex mechanical transmission and replacing it with direct electric motor drive, the system achieves counter-rotation without the weight and complexity of the removed gearbox.

Inventive Principle:
Principle #2Taking out (Extraction)

3Use of energy by moving object

If a single engine drives both propellers, then engine utilization is maximized, but the system cannot optimize for high power demand scenarios

Engineering Contradiction:
Improveengine utilizationVSAvoidhigh power demand capability
Core Design Contradiction:
Use of energy by moving objectVSPower

Solution Approach 1:

The system creates a multi-functional drive architecture where the combustion engine and electric motors can work independently or together. The electric motors can provide additional power during high power demand scenarios (take-off, climb) while the combustion engine handles normal operation, allowing the system to adapt to different power requirements without over-designing the combustion engine for peak demands.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements a dynamic power distribution system where the control unit can dynamically adjust the contribution of the combustion engine and electric motors based on real-time power demands. During high power demand, both power sources are activated; during normal operation, only the combustion engine is used, optimizing overall system efficiency.

Inventive Principle:
Principle #15Dynamics

4Power

If electric motors are added for high power demand, then power capability is enhanced, but size and weight of electrical components increase

Engineering Contradiction:
Improvehigh power demand capabilityVSAvoidelectrical system weight
Core Design Contradiction:
PowerVSWeight of moving object

Solution Approach 1:

The system uses electric motors only partially - specifically only during high power demand scenarios (take-off, climb) rather than continuously. This partial action allows the electric motors to be sized for peak power requirements only, rather than being oversized to handle all operating conditions, thereby reducing the weight of the electrical system while still providing the necessary power capability when needed.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3798119B1Drive system for counter-rotating parts
Publication Date: 2023.02.22 RATIER FIGEAC SAS
  • EP3798119B1 patent drawingFigure 1~2
  • EP3798119B1 patent drawingFigure 3

AI summary

A rotating assembly such as a counter-rotating propeller system or a turbofan, comprising a first rotating part (20) rotatable relative to a second part (21), the first and second parts mounted on a common axis (22), a combustion engine (23) arranged to rotate the first part, and an electric motor (24) connected to drive the second part, whereby in a first drive mode, the combustion engine rotates the first part in first direction relative to the axis while the electric motor drives the second part in a second, opposite direction relative to the axis and in a second drive mode, the combustion engine rotates the first part in the first direction and the electric motor does not drive the second part in the second, opposite direction.