Vehicle Torque Distribution Control for Low-Speed Steering
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Solution Overview
Problem
Conventional left-right wheel drive force distribution control systems experience a decline in fatigue life and fuel efficiency when transient control is executed during low-speed steering due to high responsiveness and trackability, leading to increased friction losses and electric power consumption.
Innovation Solution
A vehicle left-right wheel drive force distribution control apparatus that decreases the left-right drive force difference transient control amount when the steering speed is below a certain value, thereby weakening the effect of transient control in the low-speed steering region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If transient control is executed during low-speed steering, then turning responsiveness is improved, but fatigue life of power transmitting parts and fuel efficiency deteriorate
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the transient control amount based on steering speed. When steering speed is below a first threshold, the transient control amount is reduced to prevent excessive friction losses and protect power transmitting parts. When steering speed exceeds the threshold, full transient control is applied to ensure responsive turning behavior. This conditional parameter adjustment resolves the contradiction between responsiveness and reliability.
2Speed
If transient control is executed during low-speed steering, then turning responsiveness is improved, but fuel efficiency deteriorates
Solution Approach 1:
The patent reduces the transient control amount when steering speed is below a first prescribed value, thereby minimizing friction losses in the power transmitting parts during low-speed steering operations. This parameter adjustment based on steering speed conditions prevents unnecessary energy consumption while maintaining adequate turning responsiveness, thus resolving the contradiction between responsiveness and fuel efficiency.
3Speed
If transient control is executed during low-speed steering, then turning responsiveness is improved, but electric power consumption increases
Solution Approach 1:
The control apparatus adjusts the transient control amount as a parameter based on detected steering speed. When steering speed is low (below first threshold), the transient control amount is reduced, decreasing the operational demand on electric actuators and thereby reducing electric power consumption. When steering speed is high, full transient control is applied to maintain responsiveness. This dynamic parameter adjustment resolves the contradiction between responsiveness and electric power consumption.
Data Source
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AI summary
In a transient control computing section 33b, a left-right drive force difference transient control gain computing section 45 finds a left-right drive force difference transient control gain α that is smaller than 1 in a region where a target yaw rate change rate dtφ is small, i.e., a low speed steering region, and a left-right drive force difference transient control computation value calculating section 43 finds a left-right rear wheel drive force difference transient control computation value ddΔTcLR. The transient control computing section 33b then multiplies the left-right rear wheel drive force difference transient control computation value dΔTcLR by the left-right drive force difference transient control gain α to calculate the left-right rear wheel drive force difference transient control amount dΔTcLR and contributes the same to a drive force distribution control for left and right wheels (left and right rear wheels).