CVT Pseudo-Stepped Downshift Mode for Re-Acceleration Response
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Solution Overview
Problem
Conventional continuously variable transmission systems lack a pseudo-stepped downshift mode during deceleration, which affects acceleration response and deceleration feeling, as they only consider pseudo-stepped upshift during acceleration.
Innovation Solution
Implementing a transmission control method that shifts to a pseudo-stepped downshift mode during deceleration by setting downshift target rotational speeds and lower-limit target rotational speeds within the engine's high output region, allowing the transmission input rotational speed to increase to a downshift target and then decrease to a lower-limit target, repeating this process until a re-acceleration request is satisfied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a normal transmission mode is used during deceleration, then the transmission ratio changes in a stepless manner, but the acceleration response to re-acceleration requests deteriorates and the feeling of deceleration is insufficient
Solution Approach 1:
The patent segments the continuous transmission ratio change into discrete steps during deceleration, creating a pseudo-stepped downshift mode. This segmentation allows the transmission to simulate stepped-shifting behavior, improving acceleration response and deceleration feeling while maintaining the underlying continuous variable transmission mechanism.
Solution Approach 2:
The patent implements periodic upshift and downshift actions during deceleration, where the transmission ratio is repeatedly adjusted in stepwise manner. This periodic adjustment of transmission ratio creates the desired stepped-shifting effect, enhancing both acceleration response and deceleration feeling.
2Speed
If the transmission input rotational speed is increased to downshift target rotational speed in a stepwise manner, then the acceleration response improves, but the device complexity increases
Solution Approach 1:
The patent dynamically adjusts the transmission ratio through controlled upshift and downshift operations during deceleration. By making the transmission system adaptive and dynamic rather than static, it achieves improved acceleration response without requiring permanent structural modifications, thus limiting the increase in device complexity.
Solution Approach 2:
The patent changes the transmission ratio parameter in a stepwise manner during deceleration, simulating stepped-shifting behavior. By modifying operational parameters rather than physical structure, it achieves performance improvement while keeping the control system relatively simple.
Data Source
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AI summary
To achieve an improvement in an acceleration response with respect to a re-acceleration request, while improving the feeling of deceleration during deceleration by selecting a pseudo-stepped downshift mode. In a transmission control method for a belt-type continuously variable transmission (4), to an input side of which is connected an engine (1), a pseudo-stepped downshift mode for carrying out a pseudo-stepped downshift is provided as a pseudo-stepped transmission mode. The downshift target rotational speed Nta and the lower-limit target rotational speed Ntb used for the pseudo-stepped downshift are set to values in an engine rotational speed region in which an engine output becomes greater than or equal to a prescribed value. When a mode transition condition is satisfied during deceleration by selecting the normal transmission mode, the mode is shifted to the pseudo-stepped downshift mode to start the pseudo-stepped downshift. When the pseudo-stepped downshift is initiated, an increase to the downshift target rotational speed Nta and a decrease to the lower-limit target rotational speed Ntb of the primary rotational speed Npri are repeated, until the mode cancellation condition, including the re-acceleration request, is satisfied.