Hybrid Launch Clutch Control for Manual Transmission Feel
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Solution Overview
Problem
Modern vehicles equipped with automatic and hybrid automatic transmissions lack the control and responsiveness of manual transmissions, particularly in low-speed off-road driving scenarios, where manual transmissions provide greater control and reduced time lag.
Innovation Solution
A hybrid powertrain system that mimics the behavior of a manual transmission by commanding engagement of the launch clutch up to maximum creep torque capacity based on brake pedal torque, synchronizing torque provider speed with vehicle creep speed, and using existing hardware to provide a manual transmission feel in low gear, independent of vehicle speed and accelerator pedal position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a hybrid automatic transmission is used, then automation and ease of operation are improved, but control responsiveness and driver engagement deteriorate compared to manual transmissions
Solution Approach 1:
The system dynamically switches between automatic and manual-like control modes based on operating conditions. The launch clutch control system adapts its engagement strategy to mimic manual transmission behavior when appropriate, providing dynamic responsiveness while maintaining automated operation benefits
Solution Approach 2:
The control system modifies clutch engagement parameters (torque capacity, engagement rate, gradient) to replicate manual transmission characteristics. By changing these parameters dynamically, the system achieves manual-like control responsiveness within an automatic transmission framework
2Extent of automation
If conventional automatic transmission clutch engagement is used, then automation is improved, but time lag and heat generation increase due to prolonged slipping
Solution Approach 1:
The system performs preliminary synchronization of the launch clutch with the torque provider speed before full engagement. This preliminary action reduces the time required for complete clutch engagement and minimizes heat generation by optimizing the engagement sequence
Solution Approach 2:
The control system rapidly transitions the launch clutch through the engagement process once synchronization is achieved, rushing through the final engagement phase to minimize time lag and reduce heat generation from prolonged slipping
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A hybrid powertrain includes a torque provider (18), an automatic transmission (88) without a torque converter, and a transfer case (26) configured for providing four wheel drive low range. A controller receives a signal indicative of the transfer case being in low range and determines if brake pedal torque is indicative of a brake pedal being released and, if so, commands engagement of a launch clutch (72) of the transmission up to maximum creep torque capacity at a predetermined maximum gradient. The controller determines when torque provider speed is synchronized with vehicle creep speed, and upon such determination, controls the launch clutch to fully engage to a lock up state to mimic behavior of engagement of a manual transmission gear when the hybrid powertrain is in low range to thereby substantially eliminate a time lag associated with automatic transmissions having a torque converter or a constantly slipping launch clutch.