Transmission Pre-selection Mechanism Eliminates Torque Interruption
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Solution Overview
Problem
Transmission systems with multiple gear trains are prone to failure modes where two gears can be engaged simultaneously with opposing modes, leading to potential lockup during torque direction changes, especially during shifts.
Innovation Solution
A transmission system design that uses a single instantaneous selector mechanism in conjunction with non-instantaneous selector mechanisms, allowing the instantaneous selector to select multiple gear trains on one side, and employing a pre-selection mechanism to ensure seamless gear shifts without torque interruption by locking gear elements before disengaging the previous ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a discrete ratio gearbox has the ability to shift up or down ratios instantly under load without torque interruption using both engagement modes, then gearshift performance is improved, but the transmission may lock up when two gears are engaged simultaneously with opposing modes
Solution Approach 1:
The patent applies preliminary action by pre-selecting the new gear train before disengaging the old gear train. The pre-selection mechanism prepares the new gear path in advance, so when the shift occurs, the new gear is already positioned and ready to take over torque transmission immediately, eliminating the need for torque interruption while preventing simultaneous engagement of opposing gear modes
Solution Approach 2:
The patent segments the gear selection process into distinct phases: pre-selection of the new gear train, then disengagement of the old gear train. This segmentation allows the system to prepare the new gear path independently before switching, ensuring that only one gear train is actively transmitting torque at any given moment, thus preventing the lockup condition while maintaining instant shift capability
2Ease of operation
If torque direction changes during a shift, then the transmission may experience failure mode with simultaneous opposing gear engagement, but maintaining constant torque direction prevents this failure mode
Solution Approach 1:
The pre-selection mechanism prepares the new gear train in advance regardless of torque direction changes. By having the new gear path ready before the shift occurs, the system can handle torque reversals smoothly without risking simultaneous engagement of opposing gear modes, as the transition is pre-coordinated
Solution Approach 2:
The pre-selection mechanism acts as an intermediary between the old and new gear trains during torque direction changes. It mediates the transition by ensuring the new gear is prepared and positioned correctly before the old gear disengages, preventing direct conflict between opposing gear modes even when torque direction changes during the shift
Data Source
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AI summary
A transmission system including a first shaft (4;104), a first body (16;116) rotatably mounted on the first shaft (4;104), a first gear train having a first gear element (34;136) arranged to be driven by the first body (16;116) and a second gear train having a second gear element (24;143) arranged to be driven by the first body (16;116), a second body (18;118) rotatably mounted on the first shaft (4;104), a third gear train having a fifth gear element (38;132) arranged to be driven by the second body (18;118), a fourth gear train having a sixth gear element (30,139) arranged to be driven by the second body (18;118), and a first selector mechanism (46;146) arranged to selectively lock the first and second bodies (16;116,18;118) for rotation with the first shaft (4;104), wherein the first gear selector mechanism (46;146) is an instantaneous selector mechanism.