Ramp Shaft Disconnect Mechanism for Low-Stress Motor Decoupling
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Solution Overview
Problem
Existing electric motor systems face challenges in efficiently disconnecting from ancillary components while minimizing overhung moment, which requires positioning smaller components farther from the mounting flange, leading to reduced engagement diameter and increased stress on disconnect mechanisms.
Innovation Solution
A disconnect mechanism featuring a ramp shaft with a drop-in window and a ramp surface at an acute angle, allowing a plunger to engage and move the ramp shaft axially away from the disconnect shaft, reducing overhung moment and stress by using a larger diameter plunger and off-the-shelf components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If smaller components are positioned farther from the mounting flange to reduce overhung moment, then overhung moment is reduced, but the engagement diameter is reduced leading to increased stress on the disconnect mechanism
Solution Approach 1:
The patent introduces a ramp surface at an acute angle to the drop-in window, transforming the disconnect action from a purely radial engagement to one that incorporates axial movement. This dimensional change allows the plunger to engage the ramp surface and push the disconnect shaft axially, providing a mechanical advantage that reduces stress while maintaining reduced overhung moment
Solution Approach 2:
The patent changes the geometric parameters of the disconnect feature by introducing a ramp surface with a specific acute angle relative to the drop-in window. This parameter change creates a mechanical leverage system where the plunger's radial force is converted into axial displacement, reducing the stress on the disconnect mechanism while maintaining the benefits of positioning smaller components farther from the mounting flange
2Length of moving object
If the diameter of the disconnect shaft is reduced to connect smaller components, then the engagement portion on the ramp shaft is reduced, but this leads to increased stress on the plunger
Solution Approach 1:
By introducing the ramp surface at an acute angle, the patent transforms the engagement from a simple radial fit to a three-dimensional interaction where axial movement provides mechanical advantage. This allows smaller disconnect shaft diameters to be used without increasing plunger stress, as the ramp mechanism distributes the load more effectively
Solution Approach 2:
The ramp surface acts as an intermediary between the plunger and the disconnect shaft, converting the plunger's radial engagement force into axial displacement. This intermediary mechanism allows the system to use smaller disconnect shaft diameters while maintaining acceptable stress levels on the plunger through the mechanical advantage provided by the ramp geometry
Data Source
AI summary
A disconnect mechanism to disconnect an electric machine from an ancillary component includes a ramp shaft connected to a disconnect shaft of the electric machine, and connected to the ancillary component, such that when connected to the ancillary component the disconnect shaft transmits rotational energy between the electric motor and the ancillary component. The ramp shaft includes a disconnect feature. A plunger is selectably engageable with the disconnect feature to disconnect the ramp shaft from the disconnect shaft. The disconnect feature includes a drop-in window for initial engagement with the plunger, and a ramp surface extending in a circumferential direction from the drop in window at an acute angle relative to the drop in window. Engagement of the plunger with the ramp surface urges movement of the ramp shaft in an axial direction away from the disconnect shaft to disconnect the ramp shaft from the disconnect shaft.