Lock-up Clutch Control Device Torque Transition
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Solution Overview
Problem
Conventional lock-up clutch control devices experience a delay in output torque reduction when shifting from acceleration flex control to deceleration flex control, leading to insufficient torque capacity and potential engine speed blow-up.
Innovation Solution
A control device for the lock-up clutch that includes deceleration and acceleration flex-torque calculation units to determine target torque capacities, with the control unit maintaining the clutch in the acceleration flex control state until the target torque capacity calculated by the deceleration unit is reached, thereby preventing sudden torque changes and engine speed blow-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the target torque capacity of the lock-up clutch is immediately switched from the acceleration flex control state to the deceleration flex control state when the accelerator operation amount becomes zero, then the response speed of the control system is improved, but the torque capacity becomes insufficient with respect to the engine output torque, causing blow-up of engine speed
Solution Approach 1:
The control device calculates both the acceleration flex target torque capacity and deceleration flex target torque capacity in advance before switching control states. By preparing both torque capacity values beforehand and comparing them during the transition, the system ensures smooth switching without sudden torque changes that would cause engine speed blow-up.
Solution Approach 2:
The control device changes the torque capacity parameter gradually during the transition from acceleration flex control to deceleration flex control. Instead of immediately switching to the deceleration flex target torque capacity, the system adjusts the torque capacity based on the comparison between acceleration flex and deceleration flex target values, ensuring the torque capacity remains sufficient throughout the transition period.
2Reliability
If the state of the lock-up clutch is fixed to the acceleration flex control state during a predetermined time until the engine output torque decreases, then the blow-up of engine speed is suppressed, but the transition to deceleration flex control state is delayed
Solution Approach 1:
The control device continuously monitors and compares the acceleration flex target torque capacity with the deceleration flex target torque capacity during the transition period. This feedback mechanism allows the system to determine the optimal switching point based on actual torque conditions, enabling timely transition to deceleration flex control while maintaining engine speed stability throughout the process.
3Speed
If the target torque capacity is switched immediately when accelerator operation amount becomes zero, then the control responsiveness is improved, but the differential rotation speed may undershoot due to insufficient torque capacity
Solution Approach 1:
The control device calculates both acceleration flex and deceleration flex target torque capacities in advance before the control state switching occurs. By having both torque capacity values ready and comparing them during the transition, the system prevents sudden torque changes that would cause differential rotation speed undershoot while maintaining responsive control.
Data Source
AI summary
A control device includes a deceleration flex-torque calculation unit that calculates a target torque capacity of a lock-up clutch when a state of the lock-up clutch is controlled to a deceleration flex control state, an acceleration flex-torque calculation unit that calculates a target torque capacity of the lock-up clutch when the state of the lock-up clutch is controlled to an acceleration flex control state, and a control unit that controls a torque capacity of the lock-up clutch to a target torque capacity calculated by the acceleration flex-torque calculation unit, during a period until a target torque capacity calculated by the acceleration flex-torque calculation unit falls below a target torque capacity calculated by the deceleration flex-torque calculation unit, when the state of the lock-up clutch is shifted from the acceleration flex control state to the deceleration flex control state.