Vehicle Driving-Force Control Device for Sprung Vibration Suppression
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Solution Overview
Problem
Existing vehicle driving-force control systems struggle to perform sprung vibration suppression control when there is no acceleration demand, leading to gear rattle issues due to alternating target torque changes, especially during free run conditions.
Innovation Solution
A driving-force control device that includes a reversal predict means, acceleration demand judging means, vibration degree judging means, and target torque adjustment means to correct the target torque by increasing it in the negative direction when vertical vibration is high and no acceleration demand is present, and to prevent vibration suppression control when the condition is not met, thereby avoiding gear rattle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If vibration suppression control torque is added to basic demand torque, then sprung vibration suppression is improved, but gear rattle occurs due to alternating target torque symbol changes
Solution Approach 1:
The invention changes the parameter of target torque by adding a predetermined offset amount in the negative direction when reversal is predicted during free run, preventing the torque symbol from alternating while maintaining vibration suppression effectiveness
Solution Approach 2:
The invention dynamically adjusts the target torque based on predicted reversal conditions, applying offset correction only when necessary (during free run with predicted reversal) and not when acceleration demand exists, making the system adaptive to different operating conditions
2Object-generated harmful factors
If vibration suppression control is forbidden when reversal is predicted, then gear rattle is suppressed, but sprung vibration suppression control cannot be carried out during free run
Solution Approach 1:
Instead of completely forbidding vibration suppression control, the invention modifies the target torque parameter by adding an offset amount, allowing vibration suppression to continue while preventing the harmful alternating symbol behavior that causes gear rattle
Solution Approach 2:
The invention extracts only the harmful aspect (alternating torque symbol causing gear rattle) by applying offset correction, while preserving the useful aspect (vibration suppression control) during free run conditions
3Stability of the object's composition
If target torque is corrected by increasing in negative direction, then reversal alternation is prevented, but braking torque increases
Solution Approach 1:
The invention dynamically applies the offset correction only under specific conditions (when reversal is predicted during free run and no acceleration demand exists), avoiding unnecessary braking torque increase in other operating conditions
Solution Approach 2:
The offset correction is applied locally and selectively only when the specific combination of conditions is met (free run state + predicted reversal + no acceleration demand), rather than applying it universally to all operating conditions
Data Source
AI summary
In a situation where it is predicted that a symbol of target torque reverses by turns to be positive and negative alternately, the hybrid ECU carries out an increasing correction of the target torque, in which the target torque is corrected by increasing the target torque by a set amount ΔT in a negative direction when a specific condition, in which it is judged that the degree of the vertical vibration of a vehicle body is larger than a standard value and it is judged there is no acceleration demand, is satisfied, and makes the vibration suppression control torque not to be contained in the target torque when the specific condition is not satisfied. Thereby, even when carrying out free run, the sprung vibration suppression control can be carried out during bad road running, and braking force can be suppressed and fuel consumption can be improved during good road running.