Offset Clutch Assembly for Passive Starter Motor Disengagement
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Solution Overview
Problem
Conventional clutch systems in gas turbine engines require active disengagement and engagement mechanisms, which add weight, complexity, and are prone to failure, while also causing unnecessary rotation and heat generation in the starter motor when not needed.
Innovation Solution
A clutch assembly that passively disengages the starter motor from the accessory gearbox when the torque from the gas turbine engine exceeds the torque from the starter motor, and actively reengages using the axial attractive force from the starter motor's permanent magnets, eliminating the need for additional actuation systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active disengagement and engagement mechanisms are used in conventional clutch systems, then reliable clutch operation is achieved, but device complexity and weight increase
Solution Approach 1:
The clutch member utilizes its own permanent magnets to generate the axial attractive force needed for engagement, eliminating the need for external actuation systems. The permanent magnets are axially offset from the rotational axis, creating an inherent mechanical coupling that automatically engages and disengages the clutch based on rotational speed differences, making the system self-regulating without additional control mechanisms.
Solution Approach 2:
The patent removes the active disengagement mechanism from the clutch system entirely. By using passive magnetic attraction for engagement and allowing natural disengagement through speed differential, the design extracts unnecessary components, reducing complexity while maintaining functional reliability.
2Reliability
If active disengagement mechanisms are used, then clutch control is achieved, but component weight increases
Solution Approach 1:
The permanent magnets within the clutch member itself provide the engagement force, eliminating the need for separate actuators, motors, or hydraulic systems that would add weight. The system uses its own inherent magnetic properties to achieve controlled engagement and disengagement.
Solution Approach 2:
By removing active disengagement mechanisms and external actuation systems, the patent significantly reduces the moving weight of the clutch assembly while retaining full control capability through passive magnetic and mechanical means.
3Stability of the object's composition
If the starter motor remains engaged with the accessory gearbox, then continuous rotational coupling is maintained, but unnecessary rotation and heat generation occur
Solution Approach 1:
The clutch mechanism dynamically adjusts the rotational coupling between the starter motor and accessory gearbox based on operational needs. When the gas turbine engine speed exceeds the starter motor speed, the clutch passively disengages, allowing the starter motor to remain stationary and avoid unnecessary rotation and heat generation, while maintaining coupling stability when engagement is required.
Solution Approach 2:
The clutch member acts as an intermediary between the starter motor and accessory gearbox, controlling the transmission of rotational motion. It selectively engages or disengages the coupling based on speed differential, preventing direct continuous coupling that would cause energy loss through unnecessary rotation.
4Ease of operation
If conventional clutch systems are used, then engagement control is achieved, but the system is prone to failure
Solution Approach 1:
The clutch system monitors and regulates its own engagement state through the speed differential between the starter motor and gas turbine engine. This self-regulating mechanism eliminates reliance on external control systems that could fail, improving reliability while maintaining ease of operation through automatic response to speed conditions.
Solution Approach 2:
By removing active control mechanisms, sensors, and actuators from the clutch system, the patent eliminates potential points of failure associated with these components. The simplified passive mechanism has fewer parts that can malfunction, thereby improving reliability while retaining operational control through inherent mechanical and magnetic properties.
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
The clutch assembly reduces component weight and complexity, minimizes unnecessary rotation and heat generation in the starter motor, and enhances reliability by eliminating the need for active disengagement mechanisms.
Implementation Method 1
The first clutch member and the second clutch member are configured to passively disengage from each other and actively reengage with each other... actively reengaging using the axial attractive force from the starter motor's permanent magnets
Data Source
AI summary
In examples, a clutch assembly includes a first clutch member disposed near a first end of a first shaft. The first clutch member defines a first surface. The first shaft includes a starter motor coupled to a second end of the first shaft. The clutch assembly includes a second clutch member disposed near a first end of a second shaft. The second clutch member defines a second surface opposing the first surface, and the second shaft includes an accessory gearbox of a gas turbine engine coupled to a second end of the second shaft. The surfaces of the first and second clutch member engage such that rotational motion is transferred between the first clutch member and the second clutch member. The first clutch member and the second clutch member are configured to passively disengage from each other and actively reengage with each other.