Hydraulic Clutch Torque Control in Hybrid Powertrains
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Solution Overview
Problem
In hybrid powertrains, managing simultaneous input torques from internal combustion engines and electric machines to prevent clutch slip and maintain smooth vehicle acceleration is challenging due to differing reaction times, leading to abrupt changes in torque and adverse effects on drivability.
Innovation Solution
A method for controlling hydraulic line pressure in an electro-mechanical transmission by monitoring clutch reactive torque, determining the minimum required clutch torque capacity, and modulating hydraulic line pressure to prevent slip, involving the use of a distributed control module system and hydraulic circuit management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If simultaneous input torques from internal combustion engine and electric machine are applied to the transmission, then the powertrain can provide sufficient torque for vehicle acceleration, but the differing reaction times of these torque sources cause abrupt changes in torque transmission leading to clutch slip and reduced drivability
Solution Approach 1:
The control system proactively manages torque distribution from the internal combustion engine and electric machine before clutch engagement occurs. By coordinating the torque output of these torque-generative devices in advance and managing the reactive torque through the clutch, the system prevents clutch slip and ensures smooth engagement while maintaining sufficient power delivery for vehicle acceleration.
2Reliability
If hydraulic line pressure is increased to prevent clutch slip, then clutch torque capacity is maintained above reactive torque, but the hydraulic control system requires more complex pressure modulation to coordinate different torque sources
Solution Approach 1:
The control system continuously monitors the reactive torque transmitted through the clutch and dynamically modulates the hydraulic line pressure in response. This feedback mechanism ensures that the clutch torque capacity remains sufficient to handle the reactive torque from coordinated torque sources, while the hydraulic control system adjusts pressure as needed rather than maintaining constantly high pressure, thereby managing complexity through intelligent control.
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 ensures smooth operation by maintaining clutch torque capacity above reactive torque, reducing slip and improving drivability by coordinating input torques from multiple sources within the powertrain.
Implementation Method 1
A method for controlling hydraulic line pressure of a hydraulic control system in an electro-mechanical transmission... determining a hydraulic line pressure required to create the minimum clutch torque capacity... modulating hydraulic line pressure applied to the clutch
Data Source
AI summary
A method for controlling hydraulic line pressure of a hydraulic control system in an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine and an electric machine adapted to selectively transmit mechanical power to an output member via selective application of a plurality of hydraulically-applied torque transfer clutches includes monitoring requirements for transmission of clutch reactive torque in one of the clutches, monitoring a hydraulic line pressure within the hydraulic control system, determining a minimum clutch torque capacity required to keep the clutch from slipping, determining a hydraulic line pressure required to create the minimum clutch torque capacity, and modulating hydraulic line pressure applied to the clutch by modulating operation of the hydraulic control system based upon the hydraulic line pressure required to create the minimum clutch torque capacity.