Coordinated Shift Control for Vehicle Transmission Mechanisms
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Solution Overview
Problem
In vehicle transmissions, differences in shift responsiveness between mechanisms can lead to shift delays and unintended vehicle speed variations, causing a sense of incongruity for the driver during coordinated shifts.
Innovation Solution
A transmission system with a first transmission mechanism and a second transmission mechanism in series, where the second mechanism has lower shift responsiveness, is controlled to perform a coordinated shift by adjusting the speed ratio of the second mechanism opposite to the first mechanism's shift direction, setting a target speed ratio for the first mechanism based on the overall target speed ratio and actual speed ratio of the second mechanism to maintain a consistent through speed ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a coordinated shift is performed between a first transmission mechanism with higher shift responsiveness and a second transmission mechanism with lower shift responsiveness, then the overall transmission can achieve the target through speed ratio, but the second mechanism may cause shift delay leading to loss of coordinated shift and unintended vehicle speed variation
Solution Approach 1:
The control unit predicts the speed ratio of the second transmission mechanism at the timing when the first mechanism completes its shift, before the second mechanism actually completes its shift. This preliminary prediction allows the system to proactively adjust the target speed ratio of the first mechanism to compensate for the expected delay in the second mechanism, ensuring coordinated shift accuracy without waiting for the delay to manifest.
Solution Approach 2:
The control unit continuously monitors the actual speed ratio of the second transmission mechanism and uses this feedback to dynamically adjust the target speed ratio of the first mechanism. By establishing a predictive relationship between the two mechanisms based on real-time data, the system can anticipate and compensate for shift delays, maintaining coordinated shift precision despite differences in shift responsiveness.
2Device complexity
If the target speed ratio of the first transmission mechanism is set based only on the target through speed ratio without considering the actual speed ratio of the second mechanism, then the control is simple, but the deviation between target through speed ratio and actual through speed ratio increases
Solution Approach 1:
The control unit incorporates real-time feedback from the actual speed ratio of the second transmission mechanism into the determination of the target speed ratio for the first mechanism. This feedback loop ensures that the target through speed ratio remains accurate by continuously adjusting for deviations caused by the second mechanism's shift characteristics, thereby maintaining measurement precision without excessive complexity.
Solution Approach 2:
The system dynamically changes the target speed ratio parameter of the first transmission mechanism based on the actual speed ratio parameter of the second mechanism. By making the target speed ratio a variable that adapts to the real-time state of the second mechanism, the system maintains high through speed ratio accuracy while using a relatively simple control structure that relies on parameter adjustment rather than complex control logic.
Data Source
AI summary
A transmission includes a sub-transmission mechanism, a variator having lower shift responsiveness than the sub-transmission mechanism, and a controller configured to carry out a coordinated shift for changing a speed ratio of the variator in a direction opposite to a changing direction of a speed ratio of the sub-transmission mechanism as the sub-transmission mechanism is shifted so that a through speed ratio reaches a target through speed ratio. The controller sets a target speed ratio of the sub-transmission mechanism on the basis of the target through speed ratio and an actual speed ratio of the variator in carrying out the coordinated shift.