Multispeed Transmission Clutch Depth Control for Faster Shifting
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Solution Overview
Problem
Conventional multistage transmissions with actuated clutches face sub-optimal shift performance due to a static target engagement depth for dog clutches, which does not account for varying torque requirements across different gears, leading to inefficient gear shifting.
Innovation Solution
A method to dynamically control the engagement depth of the clutch based on the selected gear, using a lookup table to set the gear engagement depth specific to the target depth for each gear, allowing for deeper engagement for higher torque gears and shallower engagement for lower torque gears, thereby optimizing shift performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a static target engagement depth is used for all gears, then the clutch engagement depth is simplified to a single value, but the shift performance becomes sub-optimal due to not accounting for varying torque requirements across different gears
Solution Approach 1:
The patent applies dynamics by transitioning from a static engagement depth to a dynamic engagement depth that varies based on the selected gear. The controller adjusts the target engagement depth dynamically according to the gear selection, allowing the clutch to engage at optimal depths for different torque requirements of each gear, thereby improving shift performance while maintaining adaptive control.
Solution Approach 2:
The patent changes the parameter of engagement depth from a fixed value to a variable value that depends on the gear selection. By retrieving gear-specific target engagement depths from a lookup table and using them to control clutch engagement, the system optimizes the engagement depth parameter for each gear's torque requirements, resolving the contradiction between simplicity and performance.
2Strength
If a deeper engagement depth is used for all gears, then the torque transfer capacity is maximized, but the shifting time increases due to longer clutch movement distance
Solution Approach 1:
The patent applies local quality by assigning different engagement depths to different gears based on their specific torque requirements. Instead of using a uniform deep engagement for all gears, the system tailors the engagement depth locally to each gear's needs - deeper engagement for high-torque gears and shallower engagement for low-torque gears - thereby optimizing both torque transfer capacity and shifting time for each gear.
Solution Approach 2:
The patent changes the engagement depth parameter dynamically based on gear selection, retrieving appropriate target depths from a lookup table. This parameter adjustment ensures that each gear engages at the minimum necessary depth for its torque requirements, reducing unnecessary movement distance and shifting time while maintaining sufficient torque transfer capacity for each specific gear.
3Loss of time
If a shallower engagement depth is used for all gears, then the shifting time is reduced due to shorter clutch movement distance, but the torque transfer capacity becomes insufficient for high-torque gears
Solution Approach 1:
The patent applies local quality by customizing the engagement depth for each gear according to its torque requirements. High-torque gears receive deeper engagement depths to ensure sufficient torque transfer capacity, while low-torque gears use shallower engagement depths to minimize shifting time. This localized optimization resolves the contradiction between shifting speed and torque capacity.
Solution Approach 2:
The patent implements dynamic adjustment of engagement depth based on real-time gear selection. The controller retrieves the appropriate target engagement depth from a lookup table for the currently selected gear and adjusts the clutch engagement accordingly. This dynamic approach ensures that each gear receives the optimal engagement depth for its torque requirements, preventing both excessive shifting time and insufficient torque capacity.
Data Source
AI summary
Various methods and systems are provided for a multispeed transmission. In one example, a method to increasing a shift performance of a transmission with actuated clutches comprises controlling an engagement depth of a clutch based on a gear that is being selected by the clutch. A target engagement depth of the clutch may be retrieved from a gear selection matrix in a lookup table stored in the memory of a controller of the transmission. The target engagement depth may depend on an amount of torque expected to be transferred to the gear.