Torque Converter Lock-Up Control for Hub and Piston Wear
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Solution Overview
Problem
The existing vehicle control systems face challenges in suppressing wear between the lock-up piston and the turbine hub during engagement of the lock-up clutch, leading to excessive wear, poor engagement of the clutch, and increased workload on the oil pump due to fluid circulation.
Innovation Solution
A vehicle control apparatus that includes a control system capable of calculating the PV value (product of sliding surface pressure and sliding speed) between the hub and the cylindrical part, and when this value exceeds a threshold, the system gradually changes the engine torque to prevent excessive wear by adjusting the torque change speed or amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the lock-up clutch is engaged to directly couple the crankshaft and turbine shaft, then torque transmission efficiency is improved, but wear between the lock-up piston and turbine hub increases due to relative rotation during torque changes
Solution Approach 1:
The control system dynamically adjusts engine torque based on the PV value (product of sliding surface pressure and sliding speed) between the lock-up piston and turbine hub. When the PV value exceeds a threshold, the system limits torque increase rate to prevent excessive wear, thereby maintaining clutch durability while preserving torque transmission efficiency during normal operation
Solution Approach 2:
The control system continuously monitors the PV value between the lock-up piston and turbine hub and uses this feedback to adjust engine torque in real-time. This closed-loop control prevents wear by reducing torque change rate when sliding conditions become severe, while maintaining efficient torque transmission under normal operating conditions
2Stability of the object's composition
If the damper mechanism permits relative rotation between the hub and cylindrical part, then shock absorption is improved, but sliding wear increases between the hub and cylindrical part
Solution Approach 1:
The control system calculates the PV value between the hub and cylindrical part and adjusts engine torque accordingly. When the PV value exceeds the threshold, the system limits the torque increase rate, which reduces sliding speed and consequently reduces sliding wear while maintaining the damper mechanism's shock absorption functionality
Solution Approach 2:
The control system takes preliminary action by predicting excessive wear conditions through PV value calculation and preemptively limits torque changes before severe wear occurs. This prevents the harmful sliding wear while allowing the damper mechanism to continue providing shock absorption
Data Source
AI summary
A vehicle control apparatus is to be applied to a vehicle including a torque converter and an engine. The vehicle control apparatus includes a turbine hub, a lock-up piston, a damper mechanism, and a control system. The damper mechanism permits relative rotation between a hub of the turbine hub and a cylindrical part of the lock-up piston. The control system controls the engine. The control system calculates, with the lock-up piston engaged with a crankshaft of the engine, a PV value that is a product of a sliding surface pressure and a sliding speed between the hub and the cylindrical part. When the PV value is greater than a threshold, the control system changes an engine torque more gradually than when the PV value is equal to or less than the threshold. The engine torque is an output torque of the crankshaft.