Tapered Double-D Shaft-Hub Joint for Backlash-Free Torque Transfer
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Solution Overview
Problem
Conventional shaft/hub connections in applications like zero-radius-turning mowers experience backlash due to clearance between the axle and hub, leading to mechanical and control issues, which existing technologies like keys, splines, and conical pressure connections fail to fully eliminate.
Innovation Solution
A non-rotatable shaft/hub connection featuring a tapered, double-D configuration with angled faces and a hub with matching tapered portions, axially clamped together using a fastener to eliminate backlash by providing constant contact and compressive force during rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional shaft/hub connections with clearance are used, then ease of assembly is improved, but backlash occurs leading to mechanical wear and control issues
Solution Approach 1:
The patent employs a tapered configuration where the shaft end and hub opening both feature tapered surfaces. This curved/tapered geometry allows the components to be easily assembled while the taper angle ensures constant contact between surfaces, eliminating backlash and preventing mechanical wear during operation.
2Power
If keyed or splined connections are used, then torque transfer capability is improved, but backlash is not fully eliminated and device complexity increases
Solution Approach 1:
Instead of using traditional keyed or splined connections, the patent utilizes tapered surfaces on both the shaft end and hub opening. This curved/tapered interface provides continuous surface contact for torque transfer while eliminating backlash, achieving both high power transmission and reliability without increasing device complexity.
3Reliability
If conical pressure connections are used, then backlash is reduced, but torque transfer is limited by clamp load and friction capability
Solution Approach 1:
The patent uses tapered surfaces that maintain constant contact between the shaft and hub during rotation. This geometric configuration eliminates backlash while providing sufficient surface area and contact pressure for effective torque transfer, overcoming the limitations of clamp load and friction capability found in conventional conical connections.
4Reliability
If press fit applications with key/keyway are used, then backlash is reduced, but manufacturing complexity and difficulty increase
Solution Approach 1:
The patent employs tapered surfaces that can be manufactured using standard machining operations, avoiding the need for complex key/keyway or spline configurations. The tapered geometry provides backlash elimination through constant surface contact while maintaining ease of manufacture and assembly.
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 tapered, double-D configuration ensures a lash-free connection, preventing slippage and mechanical wear by maintaining constant contact between the shaft and hub, enhancing torque transmission and reducing unintended motion.
Implementation Method 1
a fastener extending through the bore and received by the aperture to axially clamp together the shaft and the hub
Implementation Method 2
The non-rotatable shaft/hub connection comprises a shaft having a tapered end and a bore, the tapered end providing at least two angled faces tapered end comprises a tapered, double-D configuration; and a hub having a tapered opening and an aperture, wherein the tapered opening is configured to receive the tapered end
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A non-rotatable shaft/hub connection, providing a shaft having a tapered end and a bore, the tapered end having at least two angled faces; a hub having a tapered opening and an aperture, wherein the tapered opening is configured to receive the tapered end, the tapered opening provides at least two tapered portions. The non-rotatable shaft/hub connection provides an anti-backlash shaft/hub interface, having a shaft adapted to be rotatably driven about an axis of rotation, the shaft having a tapered end providing a tapered, double-D configuration; and a hub, having an opening configured to receive the double-D configuration of the tapered end.