Vehicular Transmission Shift Drum with Half Neutral Notches
Solution Overview
Problem
Existing vehicular transmissions produce significant engagement noise when shifting gears due to a large difference in speed between the shifter and the gear, causing discomfort to vehicle occupants, especially during automatic upshift or downshift operations.
Innovation Solution
The vehicular transmission incorporates a shift drum center with equally spaced gear train establishment notches and half neutral notches, where the drum stopper arm engages the half neutral notches to temporarily increase rotational resistance and reduce rotational speed, thereby synchronizing the shifter with the gear train, minimizing the speed difference and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the shift drum center is rotatably driven intermittently to select gear positions, then the gear position selection is achieved, but a large engagement noise results due to the relatively large difference in speed between the shifter and the gear to be engaged
Solution Approach 1:
The patent introduces a preliminary gearshift mechanism that engages the shifter with the gear train before the final gear position is reached. This preliminary engagement allows the shifter and gear to synchronize their speeds in advance, reducing the speed difference at the moment of final engagement and thereby minimizing engagement noise while maintaining efficient gear position selection
Solution Approach 2:
The patent employs an intermediary engagement mechanism that acts as a mediator between the shifter and the gear train. This intermediary mechanism temporarily connects the shifter to the gear train at an intermediate position, allowing speed synchronization before the final engagement, thus resolving the contradiction between fast gear selection and noise reduction
Data Source
AI summary
A vehicular transmission includes a shift drum center with a plurality of gear train establishment notches disposed, equally spaced apart from each other, on the outer periphery thereof. The gear train establishment notches establish a specific gear train selected from among a plurality of gear trains by selectively engaging a drum stopper arm therein. The shift drum center further includes half neutral notches to be engaged with the drum stopper arm. The half neutral notches are disposed on the outer periphery of the shift drum center and at a central portion between each pair of the gear train establishment notches, respectively. The resulting configuration effectively suppresses an engagement noise during changing of a gear position through a sliding motion of a shifter.