Continuously Variable Transmission Non-Synchronization Shift Control
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Solution Overview
Problem
Synchronization shift in continuously variable transmissions requires a large amount of oil, leading to shift delays and potential inability to satisfy driver acceleration requests, especially when oil supply is limited or engine rotation speed is low.
Innovation Solution
Implementing a non-synchronization shift mechanism that allows the sub transmission mechanism to shift from the second gear position to the first gear position independently when an output increase request is made, without synchronizing with the variator, to immediately change the speed ratio to the Low side, thereby enhancing driving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization shift is performed to reduce shift shock, then shift smoothness is improved, but shift time increases and acceleration response deteriorates
Solution Approach 1:
The patent applies dynamics by making the shift control mode adjustable based on driving conditions. The control unit switches between synchronization shift mode (for normal conditions) and non-synchronization shift mode (for acceleration conditions), making the system dynamic and adaptive rather than fixed. This resolves the contradiction by selecting the appropriate shift mode according to real-time accelerator pedal position and vehicle state.
Solution Approach 2:
The patent changes the control parameters of the shift process based on driving conditions. When acceleration is requested, the control unit changes from synchronization control (where variator speed ratio changes are coordinated with sub-transmission shifts) to non-synchronization control (where only sub-transmission shifts occur). This parameter change allows the system to prioritize shift speed over shift smoothness when acceleration is needed.
2Reliability
If synchronization shift is performed, then shift shock is reduced, but oil consumption increases and shift speed decreases
Solution Approach 1:
The system dynamically adjusts the shift control strategy based on driving conditions. During acceleration requests, it switches to non-synchronization shift mode which requires less oil and executes shifts faster, while maintaining synchronization shift mode for normal conditions where smoothness is prioritized. This dynamic adaptation resolves the contradiction between shift smoothness and shift speed.
Solution Approach 2:
The control unit changes the operational parameters of the shift process by disabling synchronization control when acceleration is detected. This parameter change reduces oil demand during the shift process and increases shift execution speed, directly addressing the productivity concern while maintaining smoothness when appropriate.
3Reliability
If synchronization shift is used, then inertia torque effects are reduced, but acceleration response becomes slow
Solution Approach 1:
The patent implements dynamic control by monitoring accelerator pedal position and switching between synchronization and non-synchronization shift modes. When rapid acceleration is requested, the system immediately switches to non-synchronization mode, prioritizing acceleration response over shift smoothness. This dynamic response resolves the contradiction between reducing inertia torque effects and maintaining fast acceleration response.
Solution Approach 2:
The control unit changes the shift control parameters by disabling synchronization when acceleration is detected. This allows the sub-transmission to shift without waiting for variator speed ratio adjustments, significantly reducing shift time and improving acceleration response while accepting temporary increase in inertia torque effects during the shift.
Data Source
AI summary
A transmission controller executes synchronization shift of shifting a variator in a direction opposite to a speed ratio change direction of a sub transmission mechanism when shifting a sub transmission mechanism. When a gear position of the sub transmission mechanism is at the second gear position and an output increase request of a power source is made, the transmission controller prohibits the synchronization shift and shifts only the sub transmission mechanism from a second gear position to a first gear position.