Hybrid Vehicle Shift Control for Clutch Engagement and Overspeed Limits
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Solution Overview
Problem
Existing methods for operating hybrid vehicles struggle to optimally coordinate gear shifts and the engagement of the separating clutch, often prioritizing clutch engagement over upshifts, which can lead to rotational speed limits being exceeded, necessitating unnecessary speed governance.
Innovation Solution
A method that prioritizes the implementation of upshifts over the engagement of the separating clutch when necessary to prevent rotational speed limits from being exceeded, by checking if the upshift is critical and adjusting the engagement process accordingly, including aborting or accelerating the clutch engagement based on speed differentials and available time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engagement of the separating clutch is prioritized over the implementation of an upshift, then the clutch engagement is completed in time, but the upshift is delayed causing rotational speed to reach or exceed the limit value
Solution Approach 1:
The control method dynamically adjusts the prioritization between clutch engagement and upshift implementation based on real-time conditions. When rotational speed approaches the limit value, the system dynamically switches to prioritize upshift implementation over clutch engagement, preventing overspeed while still completing clutch engagement subsequently.
Solution Approach 2:
The system changes the control parameter priority based on the rotational speed state. When the rotational speed is below the limit value, clutch engagement is prioritized; when the rotational speed approaches or exceeds the limit value, upshift implementation is prioritized. This parameter-based switching resolves the contradiction between timely clutch engagement and rotational speed control.
2Ease of operation
If the upshift is delayed to allow clutch engagement to complete first, then the clutch engagement process is smooth, but the rotational speed exceeds the limit value requiring speed governance
Solution Approach 1:
The control method takes preliminary anti-action by detecting when rotational speed approaches the limit value and proactively prioritizing upshift implementation before the speed actually exceeds the limit. This prevents the harmful effect of overspeed from occurring in the first place, avoiding the need for corrective speed governance actions.
Solution Approach 2:
The system continuously monitors rotational speed and uses this feedback to adjust the prioritization between clutch engagement and upshift implementation. When feedback indicates rotational speed is approaching the limit value, the control system responds by prioritizing upshift implementation, thereby preventing overspeed while maintaining smooth operation.
3Speed
If the upshift is prioritized over clutch engagement when rotational speed is approaching the limit, then rotational speed limit is prevented from being exceeded, but the clutch engagement is delayed
Solution Approach 1:
The control method prepares for clutch engagement by maintaining readiness and completing the upshift first when rotational speed approaches the limit. After the upshift is completed and rotational speed is controlled, the clutch engagement is then implemented. This preliminary action sequence ensures speed control is maintained while still completing clutch engagement subsequently.
Data Source
AI summary
A method for operating a hybrid vehicle includes, depending on a presence of a control-side demand to engage a separating clutch (4), implementing an engagement process of the separating clutch (4) during driving under purely electric motor power and, depending on the presence of a control-side demand to implement an upshift in a transmission (5), implementing a gear ratio change from a current gear of the upshift into a target gear of the upshift. In response to the control-side demand to engage the separating clutch (4) and the control-side demand to implement the upshift, the method includes checking whether the upshift is necessary in order to prevent a vehicle-side rotational speed from reaching or exceeding a rotational speed limit value. When the upshift is necessary in order to prevent the vehicle-side rotational speed from reaching or exceeding the rotational speed limit value, the implementation of the upshift in the transmission is prioritized over the implementation of the engagement process of the separating clutch.