Vehicle Torque Control for Backlash Elimination and Shock Mitigation
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Solution Overview
Problem
Rattling shock occurs in vehicles with fluid transmission devices and gear mechanisms when transitioning from driven travel to driving travel, requiring effective control of input torque to maintain responsiveness while mitigating shock.
Innovation Solution
A vehicle control device with a backlash-elimination control unit that limits input torque using an electric motor, adjusting torque limits based on rotational differences to quickly transition to driving travel while minimizing rattling shock, utilizing both engine and motor-generator torque control for accurate torque management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If input torque is increased to improve responsiveness during transition to driving travel, then the transition speed improves, but rattling shock in the gear mechanism increases
Solution Approach 1:
The patent applies dynamics by making the input torque limit value variable rather than fixed. The control device dynamically adjusts the first limit value based on the absolute value of rotational difference, and switches between different limit values (first limit value, second limit value, third limit value) depending on the operational phase. This dynamic adjustment allows the system to optimize both responsiveness and rattling shock mitigation in different transition stages.
Solution Approach 2:
The patent changes the parameter of input torque limit value based on the rotational difference between input and output rotation speeds. By setting different limit values (first limit value higher than second limit value, which is higher than third limit value) corresponding to different phases of the transition process, the system achieves both quick transition and rattling shock reduction through parameter optimization.
2Stability of the object's composition
If input torque is limited to reduce rattling shock, then gear mechanism stability improves, but responsiveness during transition to driving travel deteriorates
Solution Approach 1:
The system dynamically adjusts torque limits based on the rotational difference magnitude. When rotational difference is large, a higher first limit value is applied to maintain responsiveness. When rotational difference approaches zero, the system transitions to lower limit values (second and third limit values) to reduce rattling shock, thus adapting stability control to the real-time state of the system.
Solution Approach 2:
The control device preliminarily sets appropriate torque limit values before the transition is complete. By anticipating the transition phases and pre-setting suitable limit values for each phase, the system prepares the gear mechanism in advance to handle the transition smoothly, ensuring both responsiveness and stability without waiting for the transition to occur.
3Ease of operation
If a fixed torque limit is applied throughout the transition, then control simplicity is maintained, but both responsiveness and rattling shock mitigation cannot be optimized simultaneously
Solution Approach 1:
Rather than using a fixed torque limit, the patent implements a dynamic control strategy that automatically adjusts limit values based on rotational difference and transition phase. This dynamic approach maintains ease of operation through automated phase detection and limit value selection, while significantly improving reliability by optimizing torque control for each specific transition stage.
Solution Approach 2:
The control device uses feedback from the rotational difference calculation to determine the current phase and select appropriate torque limit values. By continuously monitoring the difference between input and output rotation speeds and adjusting limits accordingly, the system achieves both automated simplicity and optimized transition performance without requiring complex manual intervention.
Data Source
AI summary
In a driven state phase, target input torque is limited to a first limit value, whereas in a backlash-elimination state phase, the target input torque is limited to a second limit value and target engine torque and torque of a motor-generator are controlled according to the target input torque. In the backlash-elimination state phase, the target input torque is limited to the second limit value that is suitable for mitigating rattling shock, so that rattling shock can be appropriately mitigated. Meanwhile, in the driven state phase, the target input torque is limited to the relatively high first limit value, so that an MG rotation speed can be quickly increased to eliminate a rotational difference, which enhances the responsiveness of driving power up to when required driving power is obtained after elimination of the backlash.