Nested Spline Torque Shaft for Multi-Rate Torsional Compliance
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Solution Overview
Problem
Vehicle drive lines with simple one-piece torque transmitting shafts have limited torsional stiffness rates, which can lead to noise, vibration, and harshness issues due to a single compliance level, failing to meet performance requirements effectively.
Innovation Solution
A torque transmitting shaft design comprising multiple members with varying torsional stiffness rates, achieved through geometric and material characteristics, including spline portions and engagement elements, allowing for different stiffness rates based on torque application and clearance conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple one-piece torque transmitting shaft is used, then the device complexity is reduced, but the torsional stiffness rate is limited and cannot provide multiple compliance levels
Solution Approach 1:
The torque transmitting shaft is divided into multiple segments (first shaft segment, second shaft segment, third shaft segment) with different torsional stiffness characteristics. Each segment can independently contribute to the overall torsional response, allowing the system to provide multiple compliance levels while maintaining a relatively simple overall structure.
Solution Approach 2:
The second shaft segment is received within the first shaft segment, creating a nested configuration. This nesting allows the inner segment to rotate relative to the outer segment, providing additional compliance while maintaining a compact structure. The engagement elements and splines enable torque transmission between nested segments with controlled relative motion.
2Ease of manufacture
If a single torsional stiffness rate is provided, then the manufacturing is simplified, but the performance requirements for noise, vibration, and harshness reduction are not met
Solution Approach 1:
Different segments of the torque transmitting shaft are designed with different local properties (torsional stiffness rates). The first, second, and third shaft segments each have distinct torsional stiffness characteristics, allowing localized optimization of vibration and noise reduction while maintaining overall structural integrity and manufacturability.
Solution Approach 2:
The shaft system transitions from a static, single-stiffness design to a dynamic, multi-stiffness system where the effective torsional stiffness can vary based on operating conditions. The engagement elements and splines allow for controlled relative motion between segments, enabling the system to adapt its compliance characteristics to different torque and vibration conditions.
3Object-affected harmful factors
If multiple members with varying torsional stiffness rates are used, then the compliance and noise, vibration, and harshness reduction are enhanced, but the device complexity increases
Solution Approach 1:
The complex requirement for multiple compliance levels is resolved by segmenting the shaft into distinct modules (first, second, and third shaft segments) with different torsional stiffness rates. This segmentation allows each module to be optimized independently while maintaining a relatively simple overall assembly process.
Solution Approach 2:
The nested configuration of the second shaft segment within the first shaft segment provides a space-efficient way to incorporate multiple compliance elements. This nesting reduces the overall axial length while providing the benefits of multiple torsional stiffness rates, thereby reducing complexity compared to a multi-stage external arrangement.
4Adaptability or versatility
If engagement elements and spline portions are used to provide multiple torsional stiffness rates, then the adaptability to varying torque conditions is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The system exploits changes in the clearance parameter between engagement elements and spline portions to achieve different torsional stiffness rates. By designing specific clearance values, the shaft can transition between compliant and stiff states based on torque conditions, allowing adaptability without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The engagement elements and splines are designed to provide partial engagement under certain conditions, allowing controlled slippage or relative motion between segments. This partial engagement mechanism enables the system to accommodate manufacturing variations while still achieving the desired multiple compliance levels through the intentional design of clearance gaps.
Data Source
AI summary
A torque transmitting shaft includes a first member and a second member. The first member extends along an axis and has an inner surface extending between a first end and a second end. The inner surface defines a plurality of first engagement elements disposed proximate the first end. The second member extends along the second axis and has a first end portion and an intermediate portion extending from the first end portion. The first end portion has a first spline portion and each member of the first spline portion is received within corresponding engagement elements of the plurality of first engagement elements.