Variable-Stiffness Splined Coupling for Backlash Reduction
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Solution Overview
Problem
Backlash in splined components leads to unwanted noise, vibration, and premature wear due to relative movement between coupled rigid mechanical components, and existing solutions like press fits or interference fits either prevent disassembly or cause unsustainable hoop stresses.
Innovation Solution
A splined coupling system with biased coupling members that are removably inserted between splined surfaces to provide variable stiffness, allowing assembly and disassembly while reducing backlash by maintaining relative position under operational forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If clearances are provided between inner and outer spline teeth to facilitate positioning and disassembly, then ease of assembly and disassembly is improved, but backlash occurs during operation causing noise, vibration, and wear
Solution Approach 1:
The patent introduces a compliant member that dynamically changes the stiffness of the coupling system. During assembly and disassembly, the compliant member allows movement to accommodate clearances. During operation, the compliant member stiffens to eliminate backlash, thus adapting the system's mechanical properties based on operational state.
Solution Approach 2:
The compliant member changes the effective stiffness parameter of the coupling system. When installed, it modifies the mechanical parameters by providing a variable stiffness connection that reduces clearances during operation while allowing them during assembly/disassembly, effectively changing the system's mechanical behavior based on need.
2Object-generated harmful factors
If press fit or interference fit is used to reduce backlash, then backlash is reduced, but high hoop stresses are produced that are unsustainable over time
Solution Approach 1:
The compliant member acts as an intermediary element between the inner and outer components. Instead of directly pressing the splined surfaces together (which creates high hoop stresses), the compliant member mediates the connection, providing the necessary force to reduce clearances while distributing stresses in a sustainable manner.
3Object-generated harmful factors
If barbs are used to secure relative position and eliminate clearances, then backlash is eliminated, but disassembly without destruction becomes impossible
Solution Approach 1:
The compliant member provides a dynamic solution where the coupling can be tight during operation (eliminating backlash) but reversible during disassembly. Unlike permanent barb connections, the compliant member's elastic or flexible nature allows it to be removed without destroying the components, enabling reusability.
4Object-generated harmful factors
If rigid coupling is used to prevent relative movement, then backlash is reduced, but the system cannot accommodate assembly clearances
Solution Approach 1:
The compliant member changes the effective stiffness parameter of the coupling system. During assembly, it allows sufficient movement to accommodate clearances and tolerances. During operation, it stiffens to reduce backlash, thus dynamically adjusting the mechanical parameters to satisfy both assembly and operational requirements.
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
Reduces or eliminates backlash-related noise, vibration, and wear by absorbing relative movement with variable stiffness, enabling assembly and disassembly without damage to components.
Implementation Method 1
a plurality of biased coupling members configured to be removably received in the plurality of openings... a biasing force exerted on the first plurality of recesses and the second plurality of recesses by the plurality of biased coupling members restricts relative movement
Data Source
AI summary
One or more variable stiffness devices may be positioned between the splined coupling of a pair of rotating mechanical components to reduce or substantially eliminate backlash during operation. The variable stiffness device may include a spring pin that exerts a variable biasing force on mating surfaces of the pair of rotating mechanical components to maintain a relative position of the components in response to rotational and/or torsional forces exerted during operation.