Drive Coupling Device Inner Quill Shaft Support
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Solution Overview
Problem
Existing drive coupling devices in aerospace applications face issues with misalignment leading to increased wear, which can hinder disconnection and cause additional loading on bearings, potentially resulting in wear or failure, especially due to centrifugal forces and insufficient support for the spring biasing the inner drive shaft.
Innovation Solution
The drive coupling device incorporates an inner quill shaft with a sleeve supporting the outer quill shaft when engaged, reducing relative radial movement and wear, and a splined coupling to accommodate misalignments, along with a stepped form to ensure clearance when disengaged, minimizing friction welding risks and supporting the outer quill shaft only when engaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outer quill shaft is supported only by bearings on the support rod, then the structure is simple, but misalignment causes increased wear on bearings and the drive coupling components
Solution Approach 1:
The inner quill shaft acts as an intermediary support element between the outer quill shaft and the support rod. When engaged, the inner quill shaft provides additional support contact points that help maintain alignment and reduce wear on both the bearings and drive coupling components, while not interfering with the disengaged state
2Reliability
If the spring biasing the inner drive shaft has insufficient support, then the structure is simpler, but fretting and wear occur between the inner drive shaft and spring
Solution Approach 1:
A support structure is introduced as an intermediary element between the spring and the inner quill shaft. This support provides adequate backing for the spring, distributing loads and preventing direct contact wear between the spring and inner quill shaft surfaces, thereby eliminating fretting while maintaining structural compactness
3Ease of operation
If reduced spacing occurs between inner and outer drive shafts due to wear, then the structure appears compact, but disconnection of the drive coupling is hindered or prevented
Solution Approach 1:
The support structure for the inner quill shaft provides continuous geometric constraint and position maintenance. By supporting the inner quill shaft along its length, the structure compensates for wear accumulation and maintains the designed spacing between inner and outer quill shafts, ensuring disconnection capability is preserved over time
Solution Approach 2:
The support structure is designed to maintain proper spacing and alignment before wear occurs. By pre-establishing the correct geometric relationship between components through structural support, the design prevents spacing degradation that would otherwise lead to disconnection problems
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 design reduces wear and load on bearings, maintains proper alignment, and ensures reliable disconnection of the drive coupling, minimizing damage to the generator and maintaining operational integrity.
Implementation Method 1
the inner quill shaft is spring biased towards the outer quill shaft so that the dog clutch arrangement is engaged
Implementation Method 2
support bearing means provided on the support rod and by which the outer quill shaft is supported for rotation relative to the support rod
Implementation Method 3
centrifugal forces and misalignment may give rise to limited radial movement
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A drive coupling device comprises an outer drive shaft (40) adapted to be driven for rotation by a gearbox output, an outer quill shaft (20) coupled to the outer drive shaft and arranged to be driven for rotation thereby, an inner quill shaft (24) arranged coaxially with the outer quill shaft and movable, axially, between an engaged position in which a dog clutch arrangement (20d, 24c) is engaged to transmit drive between the outer quill shaft and the inner quill shaft, and a disengaged position in which the dog clutch arrangement is disengaged, a support rod (26), and support bearing means (28) provided on the support rod and by which the outer quill shaft is supported for rotation relative to the support rod, wherein the outer quill shaft is further supported, when the dog clutch arrangement is engaged, by the inner quill shaft.