Gearshift Overlap Control for Faster Consecutive Downshifts
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Solution Overview
Problem
Existing gearshift control systems for automatic transmissions prolong gearshift duration and require extensive calibration, leading to inconsistent and uncomfortable acceleration responses, especially when drivers quickly accelerate.
Innovation Solution
A gearshift overlap control system using iterative learning to adjust clutch control pressures in real-time, overlapping the inertia phases of consecutive power-on downshifts to reduce gearshift duration and improve dynamic response, while minimizing calibration workload through automatic adjustment of clutch parameters based on monitored overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sequential shift control is used to execute consecutive power-on downshifts, then the control system is simple to implement, but the gearshift duration is prolonged which deteriorates acceleration response
Solution Approach 1:
The control system initiates the second power-on downshift before the first downshift is completed. The inertia phase of the second downshift is overlapped with the torque phase of the first downshift, allowing preparatory actions to be taken in advance and reducing total gearshift duration
Solution Approach 2:
The patent maintains continuous clutch engagement throughout the consecutive downshifts by overlapping the inertia phase of the second downshift with the torque phase of the first downshift. This eliminates idle time between shifts and ensures uninterrupted torque transmission, improving acceleration response
2Loss of time
If skip gearshift through neutral gear is used to shorten gearshift duration, then the gearshift duration is reduced, but it causes undesirable neutral gearshift feeling which deteriorates driving comfort
Solution Approach 1:
The patent maintains continuous clutch engagement during the gearshift process by overlapping the inertia phase of the second downshift with the torque phase of the first downshift. This continuous torque transmission eliminates the neutral gearshift feeling while still achieving shortened gearshift duration
3Loss of time
If four controlled clutches are simultaneously controlled in a single gearshift event, then the gearshift duration is reduced, but it requires huge amount of calibration work and has low robustness
Solution Approach 1:
The patent divides the gearshift control into distinct phases (filling phase, inertia phase, torque phase) and controls different clutches at different stages. The first off-going clutch is released in the filling phase, the second off-going clutch is released in the inertia phase, and on-coming clutches are engaged accordingly. This segmented approach reduces calibration complexity while maintaining short gearshift duration
Solution Approach 2:
The control system pre-calibrates clutch control parameters for individual downshift events. When consecutive downshifts are required, the system reuses these pre-calibrated parameters with temporal overlap, avoiding the need to calibrate all four clutches simultaneously and significantly reducing calibration workload
Data Source
AI summary
A gearshift overlap control system and a control method for improving vehicle dynamic response includes a gearshift progress calculation module: the gearshift progress calculation module is capable of calculating a gearshift progress in real time; a clutch control module: the clutch control module is capable of executing a first power-on downshift control and starting to perform a second power-on downshift control when a set second power-on downshift in a corresponding gearshift progress is requested; and an iterative learning control module: the iterative learning control module is capable of automatically adjusting a first on-coming clutch control pressure and a first off-going clutch control pressure in the first power-on downshift by means of monitoring the overshoot of the gearshift progress.