4WD Torque Limiting to Prevent Driveshaft Damage
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Solution Overview
Problem
Conventional 4-wheel drive vehicles face damage to front wheel driveshafts due to reduced fracture strength during turns, especially when rear wheels slip, leading to increased manufacturing costs and weight, and decreased fuel efficiency.
Innovation Solution
A method that determines the likelihood of driveshaft damage based on steering angle, accelerator opening rate, and ride height changes, and adjusts the 4-wheel drive torque limit to prevent damage by calculating the limit torque using the fracture strength and differential gear ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the size of the driveshafts is increased to attenuate the risk of damage, then the reliability of the driveshaft is improved, but the weight of the vehicle increases and fuel efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the torque limit variable rather than fixed. The torque limit is dynamically adjusted based on real-time driving conditions (steering angle, accelerator opening rate, bump stroke amount) to match the actual fracture strength requirements of the driveshaft. This allows the system to use higher torque limits when the driveshaft is strong and lower limits when it is vulnerable, eliminating the need to permanently increase driveshaft size for peak torque scenarios.
Solution Approach 2:
The patent changes the parameter of torque limit based on driving conditions. By monitoring steering angle, accelerator opening rate, and bump stroke amount, the system adjusts the torque limit parameter to reflect the current vulnerability of the driveshaft. This parameter change approach allows the same driveshaft to operate safely across different conditions without requiring size increases.
2Reliability
If the size of the driveshafts is increased to attenuate the risk of damage, then the reliability of the driveshaft is improved, but the manufacturing cost increases
Solution Approach 1:
The system dynamically adjusts torque limits based on actual driving conditions rather than designing for worst-case scenarios. This allows manufacturers to produce driveshafts with optimized, smaller dimensions that meet safety requirements under normal operating conditions, reducing material costs and manufacturing complexity while maintaining reliability through intelligent control.
Solution Approach 2:
By changing the torque limit parameter based on monitored driving conditions, the system allows standard driveshafts to operate safely without requiring expensive custom-designed oversized driveshafts. The parameter adjustment compensates for reduced driveshaft dimensions, maintaining reliability while reducing manufacturing costs.
3Reliability
If the size of the driveshafts is increased to attenuate the risk of damage, then the reliability of the driveshaft is improved, but the layout becomes disadvantageous and interference between neighboring components occurs
Solution Approach 1:
The dynamic torque limit adjustment allows the use of smaller driveshafts with more favorable dimensions. By adapting the torque limit to actual driving conditions, the system maintains reliability while enabling driveshaft designs that fit better within the vehicle's spatial constraints and reduce interference with neighboring components.
Solution Approach 2:
The patent changes the operational torque parameter to match driveshaft capabilities, allowing the use of driveshafts with optimized dimensions for the vehicle layout. This parameter adaptation enables smaller driveshaft sizes that avoid interference with surrounding components while maintaining safety through condition-based torque management.
Data Source
AI summary
A method for preventing damage to a driving system in vehicles may include determining whether a 4-wheel drive vehicle turns based on a steering angle signal, determining, based on an accelerator opening rate signal of the vehicle, whether a maximum torque causing damage to front wheel driveshafts is produced, checking a bump stroke amount of the vehicle and determining whether the front wheel driveshafts are likely to be damaged by a maximum torque transferred to the front wheel driveshafts when the vehicle turns, and lowering, when the front wheel driveshafts are likely to be damaged, a maximum torque of a 4-wheel drive torque applied to the front wheel driveshafts.