Off-Going Clutch Control for Smooth Hybrid Mode Transition
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Solution Overview
Problem
Hybrid vehicles face challenges in smoothly transitioning between operating modes due to the disengagement of clutches, which can cause driveline disturbances and potential damage, as existing control methods lack precise control over clutch slip direction and torque management during mode transitions.
Innovation Solution
A vehicle controller determines the expected slip direction of an off-going clutch and sets a non-zero reactive torque value to control the clutch's disengagement, ensuring a smooth transition by matching the speed of the driving and driven mechanisms and maintaining engagement until the torque reaches the defined value, thereby minimizing disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the clutch is disengaged during mode transition, then the vehicle can switch between operating modes, but driveline disturbances and clutch damage may occur
Solution Approach 1:
The controller determines the expected slip direction before disengagement and pre-positions the clutch torque at a non-zero value that will induce slip in the correct direction. This preliminary action ensures that when disengagement occurs, the clutch already has the appropriate torque bias to slip smoothly rather than causing driveline shock.
Solution Approach 2:
The controller dynamically adjusts the clutch torque parameter during the transition process. By setting the torque to a specific non-zero value based on the expected slip direction, the system changes the torque parameter from its steady-state value to a transition-optimized value, enabling controlled slip behavior during disengagement.
2Ease of operation
If conventional clutch control is used during mode transition, then the clutch can disengage, but slip direction cannot be precisely controlled
Solution Approach 1:
The controller uses feedback about the vehicle's operating state and the clutch's current condition to determine the expected slip direction. This feedback mechanism allows the system to adaptively set the appropriate non-zero torque value that will produce the desired slip direction, achieving precise control over the disengagement behavior.
Data Source
AI summary
A vehicle includes an engine, a motor, and a gearbox. A clutch is configured to engage to transfer a reactive torque to at least one of the engine, the motor, and the gearbox. The clutch is configured to disengage during a transition from a present operating mode to a target operating mode. A controller is configured to determine an expected slip direction of the clutch, define a non-zero value based at least in part on the expected slip direction, and command the reactive torque to the non-zero value to control the clutch to induce slip during the transition from the present operating mode to the target operating mode.