Driveshaft Joint Phasing to Minimize Cyclic Axial Forces
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Solution Overview
Problem
Existing drive shaft arrangements in motor vehicles experience significant cyclic axial forces due to the superimposition of forces from individual sliding joints, leading to issues such as noise generation, fatigue fractures, and the need for resilient elements to maintain axial positioning, which are not adequately addressed by current technologies.
Innovation Solution
A drive shaft arrangement comprising a first GI tripod joint and a second sliding joint, where the trunnion axes are inclined at an angle greater than zero degrees relative to the radial direction, and the phase angles of the joints are set to cancel out cyclic axial forces, reducing these forces through joint design and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional tripod joints with radial trunnion axes are used, then the joint structure is simple and easy to manufacture, but significant cyclic axial forces are generated leading to noise and fatigue
Solution Approach 1:
The patent changes the geometric parameter of the trunnion axis orientation from radial (0 degrees) to inclined (5-15 degrees relative to radial direction). This parameter change modifies the force distribution in the roller bodies, reducing the cyclic axial forces generated during joint operation while maintaining the basic tripod joint structure for ease of manufacture.
Solution Approach 2:
The patent employs phased arrangement of multiple tripod joints where the trunnion axes are oriented at different angular positions (e.g., 0, 120, 240 degrees). This periodic arrangement causes the cyclic axial forces from individual joints to counterbalance each other over the rotation cycle, reducing the net cyclic axial forces on the connecting shaft.
2Adaptability or versatility
If multiple sliding joints are arranged on a floating connecting shaft, then axial movements are compensated, but cyclic axial forces from superimposition of joint forces cause noise and fatigue
Solution Approach 1:
The patent arranges multiple tripod joints on the floating connecting shaft with specific phase angles between their trunnion axes. This periodic phasing ensures that as the shaft rotates and compensates for axial movements, the cyclic axial forces from each joint occur at different phases and counterbalance each other, reducing the superimposed forces while maintaining axial movement compensation capability.
Solution Approach 2:
The patent introduces asymmetric orientation of trunnion axes relative to the connecting shaft axis by inclining them at specific angles (5-15 degrees). This asymmetric configuration optimizes the force distribution and phase relationships between multiple joints, enabling better counterbalancing of cyclic axial forces while preserving the floating shaft's ability to accommodate axial displacements.
3Reliability
If resilient elements are added to maintain axial positioning, then axial positioning is improved, but device complexity increases
Solution Approach 1:
The patent enables the tripod joint system to self-regulate axial positioning through the inherent force-balancing mechanism created by inclined trunnion axes and phased joint arrangement. The system uses its own operational characteristics (cyclic force generation) to counterbalance itself, eliminating the need for external resilient elements and maintaining simplicity while improving axial positioning reliability.
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 proposed drive shaft arrangement effectively minimizes cyclic axial forces, reducing noise and fatigue while maintaining axial positioning without the need for additional resilient elements, thereby enhancing operational stability and durability.
Implementation Method 1
The inner part can be displaced along the first rotational axis relative to the outer part, with the roller bodies rolling in the respective raceway during the displacement.
Implementation Method 2
the trunnion axes are inclined with respect to the radial direction. This is intended to reduce the cyclic axial forces that arise when the joint is deflected.
Data Source
AI summary
A drive shaft assembly for a motor vehicle, has at least a first tripod joint having a first outer part and a first inner part having three first trunnions with first trunnion axes. A second sliding joint has a second outer part and a second inner part, and a connecting shaft which extends along an axial direction between a first end and a second end and which is connected in a torque-transmitting manner via the first end to the first tripod joint and via the second end to the second sliding joint. At least the trunnion axes of the first trunnions are inclined relative to a radial direction by a first angle of inclination which is greater than zero angular degree.