Dual-Clutch Downshift Control for Stronger Deceleration Feedback
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Solution Overview
Problem
Dual-clutch, servo-assisted transmission systems in vehicles do not effectively convey the expected significant change in longitudinal deceleration during downshifts to drivers, leading to a perception of compromised performance, despite improved gear shift sensations in existing methods.
Innovation Solution
A method controlling the execution of a downshift by synchronizing the rotation speed of the internal combustion engine with the incoming clutch, using the kinetic energy of the vehicle to increase torque transmission, and temporarily overclosing the incoming clutch to enhance the deceleration sensation, while avoiding wheel blockage risks by activating the engine to assist torque synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a progressive gear ratio shortening is used during downshift in dual-clutch transmission, then gear shift performance is improved, but driver perception of deceleration change is reduced
Solution Approach 1:
The patent applies dynamics by making the gear ratio change progressive rather than instantaneous. The control system dynamically adjusts the gear ratio over time during the downshift, creating a smooth transition that maintains performance while managing the deceleration sensation. This is achieved through continuous modulation of clutch engagement and torque distribution during the shift event.
Solution Approach 2:
The patent changes the parameter of gear ratio from a discrete step change to a continuous progressive change. By controlling the rate and profile of gear ratio reduction, the system optimizes both performance and driver perception. The control algorithm adjusts torque distribution and clutch engagement parameters to shape the deceleration curve during downshift.
2Ease of manufacture
If the incoming clutch is overclosed to enhance deceleration sensation, then driver perception of performance is improved, but wheel blockage risk increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring wheel speed, clutch engagement state, and vehicle deceleration. The control system uses this feedback to dynamically adjust the incoming clutch engagement profile, preventing excessive torque transmission that could cause wheel blockage. The feedback loop ensures the deceleration sensation remains strong while maintaining safety margins.
Solution Approach 2:
The patent applies preliminary anti-action by preparing the engine and clutch system in advance to counteract potential wheel blockage. The engine is activated or its torque is adjusted beforehand to provide a counter-torque that prevents the incoming clutch from transmitting excessive force to the wheels. This preemptive measure eliminates the harmful effect before it can occur.
3Speed
If the engine is activated to assist torque synchronization, then synchronization speed is improved, but energy consumption increases
Solution Approach 1:
The patent applies preliminary action by activating the engine or adjusting its torque output before the actual downshift event. This allows the engine to be pre-synchronized with the incoming clutch gear, reducing the synchronization time and torque disruption during the shift. The preliminary engine activation ensures smoother and faster synchronization while minimizing the duration of energy consumption.
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
The method provides a sports-like driving sensation with improved performance perception, maintaining driving comfort and safety by managing deceleration peaks and avoiding wheel blockage, while being economically and easily implementable without additional hardware.
Implementation Method 1
controlling the incoming clutch between the second instant and the third instant so as to have the incoming clutch temporarily transmit a greater torque than the braking torque of the internal combustion engine in order to accelerate the internal combustion engine using the kinetic energy owned by the road vehicle
Implementation Method 2
The internal combustion engine is activated in the second time instant and is deactivated in the third time instant so as to generate a torque that helps increase the rotation speed of the internal combustion engine
Data Source
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AI summary
A method to control the execution of a shift to a lower gear while an accelerator pedal (22) is released in a drivetrain (6) provided with a dual-clutch, servo-assisted transmission (7); the control method comprises the following steps: opening, in a first instant (ti), an outgoing clutch (16A); closing, in the first instant (ti), an incoming clutch (16B); completing the opening of the outgoing clutch (16A) and the closing of the incoming clutch (16A) in a second instant (t2); synchronizing, between the second instant (t2) and a third instant (t3), a rotation speed (ωE) of the internal combustion engine (4) with a rotation speed (ωB) of the incoming clutch (16B); and controlling the incoming clutch (16B) between the second instant (t2) and the third instant (t3) so as to have the incoming clutch (16B) temporarily transmit a greater torque (TB) than the torque (TB) that the clutch (16B) is going to transmit immediately after the shift to a lower gear and than the torque (TA) that the outgoing clutch (16A) transmitted immediately before the shift to a lower gear.