AMT Downshift Synchronization Pause to Reduce Shift Shock
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Solution Overview
Problem
Conventional automated manual transmissions (AMTs) with double clutch transmissions (DCTs) experience shift shock and noise during downshifting due to backlash between the input and output shafts, leading to reduced vehicle quietness and comfort.
Innovation Solution
A method of controlling the transmission by maintaining synchronization between the speed shift gear and output shaft for a predetermined time after synchronization is complete, and then completing gear engagement, using an actuator to control the sleeve's movement and position to prevent backlash rearrangement and subsequent shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the sleeve is moved linearly by the actuator to complete gear engagement quickly, then the gear shifting speed is improved, but shift shock and noise occur due to backlash rearrangement
Solution Approach 1:
The patent applies preliminary action by pausing the sleeve movement at the synchronization completion position before final engagement. This pause allows the backlash elements to rearrange smoothly in advance, preventing shock and noise when the sleeve completes the engagement movement. The actuator controls the sleeve to stop temporarily at a predetermined position, then proceeds with final engagement after the pause period.
Solution Approach 2:
The patent implements periodic action by dividing the sleeve movement into distinct phases: initial movement to synchronization position, pause period, and final engagement movement. This periodic control pattern allows the system to manage backlash rearrangement in stages, reducing shock and noise while maintaining overall gear shifting speed.
2Object-affected harmful factors
If the synchronization is maintained for a predetermined time, then shift shock and noise are prevented, but the gear shifting time increases
Solution Approach 1:
The patent applies partial action by implementing a pause of predetermined time period at the synchronization completion position, which is sufficient to allow backlash elements to rearrange smoothly, but not excessively long to cause significant delay. This optimized pause duration balances shock prevention with time efficiency.
3Productivity
If the sleeve moves continuously without pausing, then the gear shifting process is efficient, but the backlash elements collide causing shock
Solution Approach 1:
The patent uses preliminary action by pausing the sleeve at the synchronization completion position before final engagement. This preliminary pause allows backlash elements to rearrange smoothly, preventing collision and shock during the final engagement phase, while maintaining overall shifting efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach prevents shift shock and noise, enhancing gear shift quality, quietness, and riding comfort, thereby improving vehicle marketability.
Implementation Method 1
the rpm of the second input shaft becomes equal to that of the output shaft... if there is no frictional resistance induced as a result of the rotation of the second input shaft
Data Source
AI summary
A method of controlling a transmission of a vehicle may include beginning synchronization between a speed shift gear of a target gear and an output shaft to shift gears from a current gear to a lower gear set as the target gear in response to deceleration of the vehicle, after the synchronization between the output shaft and an input shaft by the speed shift gear of the target gear has been completed, maintaining the synchronized state therebetween for a predetermined time period, and completing engagement with the target gear to complete the shifting of the gears after the maintaining of the synchronized state.