Vehicle Torque Control for Zero-Crossing Shock Suppression
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Solution Overview
Problem
In vehicles with a drive shaft and a drive force distribution device, shocks occur when the torque output crosses zero due to differences in backlash influence between the front and rear wheels, which existing control methods fail to adequately suppress, especially when the driving side distribution ratio is small.
Innovation Solution
A vehicle control method that employs an electronic control unit to execute a moderate change process on the required torque for the drive shaft, adjusting the target torque output to the drive shaft by setting a more moderate change in relation to the required torque, particularly when the driving side distribution ratio is small, to mitigate the impact of backlash and mechanical mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a uniform rate value is used for the rate process on required torque regardless of driving side distribution ratio, then the control process is simple, but the shock cannot be sufficiently suppressed when torque output crosses zero and driving side distribution ratio is small
Solution Approach 1:
The patent applies dynamics by making the rate value dynamic rather than uniform. The control device selects different rate values based on the driving side distribution ratio and torque direction. When the distribution ratio is small and torque is positive, a smaller rate value is selected to suppress shock; otherwise, a larger rate value is used. This dynamic adjustment resolves the contradiction between control simplicity and shock suppression.
Solution Approach 2:
The patent changes the parameter of rate value based on operating conditions. By selecting from multiple predetermined rate values according to the driving side distribution ratio and torque sign, the system optimizes shock suppression while maintaining reasonable control complexity. This parameter change approach allows adaptive control without overly complicating the control logic.
2Speed
If the target torque changes rapidly to follow required torque, then the responsiveness is high, but the shock occurs when torque output crosses zero due to backlash in mechanical mechanisms
Solution Approach 1:
The patent applies preliminary anti-action by anticipating the shock problem before it occurs. When the torque output is positive and crossing toward zero with a small distribution ratio, the system proactively selects a smaller rate value to moderate the torque change. This preliminary adjustment prevents the backlash-induced shock before it happens, rather than reacting after the shock occurs.
Solution Approach 2:
The system provides beforehand cushioning by selecting appropriate rate values in advance based on the operating state. When conditions indicate potential shock (positive torque, small distribution ratio), a cushioning rate value is selected beforehand to soften the torque transition. This approach cushions against the impending shock while maintaining acceptable responsiveness in other operating conditions.
Data Source
AI summary
A vehicle includes driving wheels, driven wheels, a drive device connected to a drive shaft, a drive force distribution device, and an electronic control unit configured to execute a moderate change process on a required torque required for the drive shaft to set a target torque to be output to the drive shaft when the torque output to the drive shaft changes and crosses a value of zero. The electronic control unit is configured to control the drive device such that the target torque is output to the drive shaft, and set the target torque such that a change in the target torque with respect to a change in the required torque is more moderate when the driving side distribution ratio is small compared with the change in the target torque with respect to the change in the required torque when the driving side distribution ratio is large.