Driveline Disconnect Clutch Pressure Boost Adaptation for Timing Stability
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Solution Overview
Problem
The operation of a driveline disconnect clutch in hybrid vehicles is prone to variations due to changes in fluid viscosity with temperature and part-to-part variability, leading to inconsistent torque transfer and drivability issues.
Innovation Solution
Adjusting the boost pressure supplied to the driveline disconnect clutch via a controller based on the difference between expected and observed clutch pressures, allowing for real-time compensation for delays and torque capacity errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If open loop control adjustments are provided to compensate for fluid temperature changes and variability, then the driveline disconnect clutch operation can be partially compensated, but timing variation in clutch closure and torque transfer cannot be sufficiently reduced
Solution Approach 1:
The patent implements a feedback control system that monitors the actual clutch pressure and compares it to the commanded pressure. A feedback gain is applied to adjust the boost pressure command based on the pressure error, creating a closed-loop control system that actively compensates for timing variations and ensures consistent torque transfer timing despite fluid viscosity changes and part variability.
2Speed
If boost pressure is increased to accelerate clutch closure and reduce timing variation, then response time improves, but pressure control precision and torque capacity accuracy deteriorate
Solution Approach 1:
The patent employs dynamic boost pressure adjustment where the boost gain is not fixed but adapts based on operating conditions and pressure errors. The system dynamically modulates the boost pressure magnitude during clutch engagement, applying higher boost when needed to accelerate closure and reducing it to maintain precision, thereby achieving both fast response and accurate pressure control.
Solution Approach 2:
A feedback control mechanism continuously monitors the pressure error between commanded and actual clutch pressure. The feedback gain adjusts the boost pressure command in real-time based on this error, allowing the system to accelerate clutch closure when lag is detected while maintaining precise pressure control when the clutch is near the target state, thus resolving the trade-off between speed and precision.
3Adaptability or versatility
If fluid viscosity changes due to temperature variation are compensated through open loop adjustments, then general operation is improved, but part to part variability cannot be fully addressed
Solution Approach 1:
The feedback control system continuously monitors actual clutch pressure and adjusts the boost pressure command based on the difference between commanded and actual pressure. This closed-loop approach compensates for both temperature-induced viscosity changes and part-to-part variability, as the feedback mechanism adapts to each specific clutch's actual response characteristics rather than relying on pre-programmed compensation tables.
Solution Approach 2:
The system changes the boost pressure parameter dynamically based on operating conditions and observed pressure errors. By adjusting the boost pressure magnitude and timing according to actual clutch response, the system adapts to different fluid viscosities caused by temperature variations and compensates for manufacturing tolerances between individual clutches, achieving consistent performance across varying conditions.
Data Source
AI summary
Systems and methods for operating a driveline of a hybrid vehicle are presented. In one example, the systems and methods adjust a driveline disconnect clutch boost time duration or magnitude responsive to a pressure error and a time delay error. A driveline disconnect clutch may be operated via supplying a pressure to the driveline disconnect clutch that includes the adjusted boost time duration or magnitude.