Cardan Joint Driveline Torque Compensation for Smoother Rotation
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Solution Overview
Problem
The use of cardan joints in vehicle drivelines introduces torque oscillations, which can disturb vehicle occupants and is financially more expensive than constant velocity joints, while constant velocity joints are cost-prohibitive.
Innovation Solution
Adjusting the torque output of a propulsion source, such as an electric machine, to counteract torque pulsations caused by cardan joint speed changes, ensuring smoother driveline rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cardan joint is used to connect the propulsion source to the wheel, then the driveline can accommodate relative motion between the wheel and propulsion source, but torque oscillations are introduced that disturb vehicle occupants
Solution Approach 1:
The system dynamically adjusts the torque parameter delivered by the propulsion source based on the instantaneous angle of the cardan joint. By monitoring the joint angle and modifying torque output accordingly, the system compensates for the inherent torque oscillations generated by the cardan joint, thereby reducing harmful vibrations while preserving the joint's adaptability to relative motion
Solution Approach 2:
The system employs a feedback mechanism where the cardan joint angle is continuously monitored and used to adjust the propulsion source torque command. This closed-loop control allows the system to detect torque oscillation conditions and respond by modifying torque delivery to counteract the harmful effects, while maintaining the necessary mechanical flexibility
2Object-generated harmful factors
If a constant velocity joint is used instead of a cardan joint, then torque transfer is constant and smooth, but the financial cost increases
Solution Approach 1:
The system uses the less expensive cardan joint instead of the costly constant velocity joint, accepting that the cardan joint generates torque oscillations. However, it compensates for this deficiency through active control of the propulsion source torque, thereby achieving smooth torque delivery without incurring the high cost of a constant velocity joint
Solution Approach 2:
Instead of replacing the cardan joint with a more expensive mechanical solution (constant velocity joint), the system substitutes the mechanical function of constant velocity delivery with an active control system that electronically adjusts torque output. This replaces a mechanical upgrade with a control-based solution, reducing overall system cost
Data Source
AI summary
Methods and systems for operating a driveline that includes a cardan joint are described. In one example, electric machine torque is adjusted in response to driver demand torque and a torque to compensate for cardan joint rotation. The electric machine torque adjustments operate to cancel driveline torque variation that may be induced via the cardan joint.