Driveline Disconnect Clutch Pressure Compensation for Torque Stability
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Solution Overview
Problem
The driveline disconnect clutch in hybrid vehicles experiences torque disturbances and increased energy consumption due to unintended changes in pressure, caused by variations in transmission line pressure, which can lead to driveline losses and compromised drivability.
Innovation Solution
Adjusting the driveline disconnect clutch pressure in response to changes in commanded transmission line pressure to counteract these changes, thereby maintaining consistent clutch pressure and reducing torque disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transmission line pressure is varied based on vehicle operating conditions, then the transmission can accommodate gear shifting and operating conditions, but driveline disconnect clutch pressure changes unintentionally causing torque disturbances
Solution Approach 1:
The pressure control system is segmented into two independent control paths: one for transmission line pressure (affecting gear clutches) and one for driveline disconnect clutch pressure. This allows the transmission to vary line pressure for gear shifting while the driveline disconnect clutch pressure is independently maintained or adjusted to prevent torque disturbances.
Solution Approach 2:
Different pressure control strategies are applied to different parts of the hydraulic system. The transmission line pressure is varied globally to accommodate various operating conditions, while the driveline disconnect clutch pressure is controlled locally with specific compensation to maintain torque stability and prevent disturbances.
2Reliability
If driveline disconnect clutch pressure is increased when stroked, then clutch engagement is improved, but driveline losses and energy consumption increase
Solution Approach 1:
The driveline disconnect clutch pressure is made dynamic rather than static. The pressure is adjusted in real-time based on the clutch state and transmission line pressure conditions. When the clutch is stroked (disengaged), the pressure is reduced to minimize driveline losses and energy consumption, while still maintaining sufficient pressure when engagement is needed.
3Loss of energy
If driveline disconnect clutch pressure is decreased when stroked, then energy consumption is reduced, but engagement delays occur causing torque disturbances
Solution Approach 1:
The system performs preliminary actions by monitoring transmission line pressure changes and proactively adjusting driveline disconnect clutch pressure before engagement issues occur. When line pressure changes are detected, the driveline disconnect clutch pressure is compensated in advance to maintain proper engagement timing and prevent torque disturbances.
Solution Approach 2:
The pressure control system uses feedback from transmission line pressure sensors and clutch position sensors to continuously adjust driveline disconnect clutch pressure. This closed-loop control ensures that pressure is maintained at optimal levels for engagement while minimizing energy loss during disengaged states.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces driveline torque disturbances, minimizes driveline losses, and enhances vehicle drivability by maintaining consistent clutch pressure during line pressure changes.
Implementation Method 1
The driveline disconnect clutch may be hydraulically actuated via transmission fluid that is supplied by a pump. The pump may also supply transmission gear clutches with fluid so that the transmission may shift between its fixed gear ratios.
Implementation Method 2
The output pressure of the pump may be regulated to a line pressure that is varied based on vehicle operating conditions.
Data Source
AI summary
Systems and methods for operating a driveline disconnect clutch of a hybrid vehicle are presented. In one example, torque capacity of a driveline disconnect is adjusted in response to a change in commanded line pressure. The torque capacity of the driveline disconnect clutch may be adjusted in according to a maximum transmission line pressure.