Driving Force Distribution Controller Torque Management
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Solution Overview
Problem
Conventional four-wheel drive vehicles face challenges in managing torque during deceleration, leading to increased stress on driving force transmission members due to the generation of large torque in the direction of deceleration, which can compromise component reliability and fuel efficiency.
Innovation Solution
A driving force distribution controller that adjusts torque transmission to auxiliary drive wheels based on engine rotational speed and vehicle speed, using a control device to calculate and reduce torque when specific thresholds are met, thereby minimizing deceleration torque and ensuring reduced stress on transmission members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If support stiffness of driving force transmission member is increased to withstand maximum deceleration torque, then reliability is improved, but weight increases and fuel efficiency deteriorates
Solution Approach 1:
The control device preemptively reduces torque transmission to auxiliary drive wheels when deceleration conditions are detected (engine speed below threshold and vehicle speed above threshold), preventing large deceleration torque from generating in the first place. This preliminary counter-action eliminates the need for oversized support members designed to withstand maximum potential torque.
Solution Approach 2:
The invention dynamically changes the torque transmission parameter based on operating conditions. By monitoring engine speed and vehicle speed, the system adjusts the torque value transmitted to auxiliary drive wheels, reducing it under specific deceleration conditions. This parameter adaptation allows using lighter support members that only need to withstand the reduced, condition-dependent torque rather than maximum possible torque.
2Reliability
If support stiffness of driving force transmission member is increased to withstand maximum deceleration torque, then reliability is improved, but device complexity increases
Solution Approach 1:
The control device preemptively reduces torque transmission to auxiliary drive wheels when deceleration conditions are detected, preventing large deceleration torque from generating. This eliminates the need for complex support structures designed to withstand maximum potential torque, allowing simpler, lighter components.
Solution Approach 2:
The invention introduces dynamic control of torque transmission based on real-time monitoring of engine speed and vehicle speed. The torque value is continuously adjusted according to operating conditions, transforming a static, over-engineered support structure into a dynamically adapted system that only requires support for the actual, reduced torque levels.
3Device complexity
If torque transmission to auxiliary drive wheels is controlled based on vehicle speed only, then simplicity is maintained, but harmful deceleration torque is generated
Solution Approach 1:
The control device performs preliminary assessment by checking both engine speed and vehicle speed before reducing torque transmission. This preliminary action identifies deceleration conditions early, allowing the system to prevent harmful deceleration torque from generating while maintaining simple control logic based on straightforward threshold comparisons.
Data Source
AI summary
A driving force distribution controller comprises: a control device determining the value of torque which must be transmitted to a rear wheel; and a driving force transmission device transmitting torque corresponding to the torque value determined by the control device to the rear wheel. The control device reduces a torque value calculated based on an opening degree of an accelerator and a rotational speed difference when the rotational speed of an engine is lower than a first threshold value but higher than a second threshold value.