Multi-rate torsional driveline joint with adaptive stiffness
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Solution Overview
Problem
Current vehicle driveline systems lack the ability to provide a multi-rate torsional stiffness, which is essential for efficient energy transfer and noise vibration harshness (NVH) management, as they either offer constant stiffness or fail to adapt to varying torque levels effectively.
Innovation Solution
The driveline joint design incorporates an outer member, an inner member, a cage, and a biasing member, featuring ball grooves and complementary grooves, along with a preload mechanism, to adjust torsional stiffness in response to input torque levels, providing low stiffness at low torques and increased stiffness as torque thresholds are exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple one-piece bar drive shaft is used, then the device complexity is reduced, but the ability to provide multi-rate torsional stiffness is lost
Solution Approach 1:
The drive shaft is divided into multiple modular sections (inner shaft, outer shaft, intermediate sections) that can independently rotate relative to each other. This segmentation allows each section to contribute differently to torsional stiffness based on operating conditions, enabling multi-rate stiffness characteristics while maintaining a relatively simple overall structure.
Solution Approach 2:
The drive shaft incorporates dynamic elements including spring-loaded ball grooves and complementary grooves that automatically adjust the engagement state based on torque levels. At low torque, the balls disengage allowing relative rotation and lower stiffness; at high torque, the balls engage to provide higher stiffness, creating a dynamically adaptive system.
2Manufacturing precision
If constant torsional stiffness is provided, then the manufacturing precision is simplified, but the NVH performance is degraded
Solution Approach 1:
The system automatically changes the torsional stiffness parameter in response to varying torque conditions. The spring-loaded ball groove mechanism transitions between engaged and disengaged states, effectively changing the stiffness parameter from high to low or vice versa, thereby optimizing NVH performance across different operating regimes without requiring complex manufacturing tolerances.
3Object-affected harmful factors
If multi-rate torsional stiffness is implemented, then the NVH performance is improved, but the device complexity increases
Solution Approach 1:
The drive shaft incorporates self-regulating mechanisms where the spring-loaded balls automatically engage or disengage based on the applied torque, without requiring external control systems. The system serves itself by using the operational conditions (torque levels) to automatically adjust its stiffness characteristics, reducing the need for additional control components.
Solution Approach 2:
The design places the inner shaft within the outer shaft, with intermediate sections nested between them. The ball grooves and complementary grooves are nested within the shaft structure, allowing multiple functional elements to occupy compact spaces. This nesting approach enables complex multi-rate stiffness functionality while maintaining a space-efficient and relatively simple overall configuration.
4Ease of manufacture
If a single torsional stiffness is used, then the ease of manufacture is improved, but the energy transfer efficiency is reduced
Solution Approach 1:
The drive shaft employs dynamic torque-coupling mechanisms that automatically adjust the torsional stiffness based on power transmission requirements. During high-torque conditions, the mechanism engages to provide high stiffness for efficient energy transfer; during low-torque conditions, it disengages to allow flexibility. This dynamic adaptation optimizes energy transfer efficiency across varying operating conditions without requiring complex manufacturing processes.
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 enhances NVH performance by isolating powertrain components at low torques and enabling efficient energy transfer at higher torques, improving overall driveline efficiency and vehicle performance.
Implementation Method 1
The first biasing member is received within the outer member and is disposed between the second portion and the end portion
Implementation Method 2
The cage is configured to position a plurality of balls relative to the plurality of ball grooves and the plurality of complementary ball grooves
Data Source
AI summary
A driveline joint includes an outer member, an inner member, and a biasing member. The outer member is connected to a first shaft and has a back wall, an end portion, and an inner surface extending between the back wall and the end portion. The inner member is connected to a second shaft and has a first end, a second end, and an outer surface extending between the first end and the second end. The biasing member is disposed between the back wall and the first end and resists translation of the inner member relative to the outer member.