CVT Manual Shift Control for Consistent Engine Speed Changes
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Solution Overview
Problem
Existing continuously variable transmission systems in manual mode cause uneven changes in input rotation speed when shifting to a fixed transmission ratio, leading to an awkward driving experience due to varying engine rotation speed changes based on timing and vehicle speed.
Innovation Solution
A control device that stabilizes input rotation speed changes by implementing a manual mode where the engine rotation speed is altered by a predetermined speed regardless of vehicle speed, using a combination of long-press and click shift controls to manage shift operations and adjust transmission ratios based on driver intent and drive mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the transmission ratio is changed to a predetermined fixed transmission ratio in manual mode, then the shift operation can be performed according to driver's input, but the variation in input rotation speed becomes different depending on timing of change to manual mode, causing awkward feeling to driver
Solution Approach 1:
The patent changes the control parameter from fixed transmission ratio to fixed input rotation speed change amount. When manual mode is activated, the system controls the variator to achieve a predetermined change in input rotation speed (ΔN) rather than shifting to predetermined fixed transmission ratios. This parameter change ensures consistent driver experience regardless of timing or vehicle speed conditions.
2Adaptability or versatility
If the transmission ratio is continuously varied according to travelling state, then the transmission can adapt to different driving conditions, but the input rotation speed variation becomes unpredictable when manual mode is engaged
Solution Approach 1:
The patent implements a dynamic control strategy where the variator ratio is adjusted in real-time to achieve the target input rotation speed change. The control device calculates the required variator ratio change based on current driving conditions and driver input, then dynamically adjusts the variator to achieve the predetermined input rotation speed change amount (ΔN). This dynamic approach maintains reliability across varying travel conditions.
3Extent of automation
If the shift is performed to predetermined fixed transmission ratio, then the manual mode can be implemented, but the variation in engine rotation speed changes based on timing and vehicle speed, leading to driver discomfort
Solution Approach 1:
The patent employs feedback control where the control device continuously monitors the actual input rotation speed and compares it with the target value. Based on this feedback, the system adjusts the variator ratio to ensure the input rotation speed changes by the predetermined amount (ΔN). This feedback mechanism eliminates driver discomfort by ensuring consistent behavior regardless of timing or vehicle speed conditions.
Data Source
AI summary
A continuously variable transmission has a variator (4) structured to be able to continuously vary a transmission ratio and a control unit (100). The control unit (100) continuously varies a transmission ratio of the variator (4) in a continuously variable shift mode. In a manual mode in which a manual mode switch (36c) is ON, the transmission ratio is maintained. When a shift switch (36a, 36b) is operated by a driver during the manual mode, the control unit (100) performs shift of the variator (4) so as to change an input rotation speed of the variator (4) by a predetermined rotation speed (ΔN1) regardless of a vehicle speed.