Shift Drum Intermediate Locking for Smoother Sequential Gear Changes
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Solution Overview
Problem
Sequential transmissions in motorcycles and other two-wheelers face challenges in achieving reproducible and comfortable gear changes across various operating ranges, especially when load on the drive train is low, leading to insufficient speed synchronization and noise during gear changes.
Innovation Solution
A device and method for locking a shift drum with a shift axis and an actuator that holds the shift drum in an unstable intermediate position between stable positions, preventing further rotation until speed synchronization is achieved, using an actuator that can be controlled to engage and disengage for smooth and noiseless gear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a shift assist system is used to facilitate gear changes, then ease of operation is improved, but under light load conditions the shift may occur without sufficient speed synchronization leading to noise and discomfort
Solution Approach 1:
The actuator is activated before the gear change is complete to preliminarily lock the shift drum in an intermediate position. This preliminary action allows speed synchronization to occur while preventing premature engagement, ensuring that when the gear finally engages, the speeds are synchronized and noise is minimized.
Solution Approach 2:
The actuator serves as an intermediary mechanism between the shift drum and the locking mechanism. It temporarily holds the shift drum in an intermediate position, mediating between the incomplete gear change and the final engaged state, allowing speed equalization to occur during this intermediate phase.
2Ease of operation
If the shift drum is allowed to rotate freely during gear change, then ease of operation is improved, but speed synchronization cannot be ensured leading to harmful noise
Solution Approach 1:
The actuator performs a preliminary locking action at the intermediate position before final gear engagement. This preliminary constraint on rotation ensures that speed synchronization can be achieved reliably, while still allowing the gear change process to proceed smoothly through the intermediate phase.
Solution Approach 2:
The system dynamically transitions the shift drum from a free-rotating state to a constrained intermediate position, then to the final engaged position. This dynamic control allows the system to balance between free rotation for smooth operation and constrained rotation for speed synchronization.
3Reliability
If an actuator is added to lock the shift drum in intermediate position, then speed synchronization is improved, but device complexity increases
Solution Approach 1:
The actuator is designed to perform multiple functions: it locks the shift drum in the intermediate position for speed synchronization, and can be integrated with the existing shift assist system control architecture. This multi-functionality justifies the added complexity by providing multiple benefits from a single component.
Solution Approach 2:
The actuator replaces or supplements traditional mechanical locking mechanisms with a more controllable actuation system. This substitution allows for precise control of the intermediate position and timing, improving speed synchronization reliability while using modern actuation technology that can be efficiently controlled by the existing engine control unit.
4Productivity
If gear change occurs without actuator intervention, then productivity is improved, but transmission protection is compromised due to insufficient speed matching
Solution Approach 1:
The actuator performs a preliminary locking action that temporarily halts the shift drum rotation at the intermediate position. This preliminary intervention ensures speed synchronization occurs before final engagement, protecting the transmission from damage while still allowing relatively quick gear changes by maintaining the ability to complete the shift promptly after synchronization.
Data Source
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Figure 3
AI summary
The invention relates to a device for arresting a controller cylinder (14) of a sequential transmission (10), comprising an actuator (48), which can be transitioned into an activated state by means of a control device. In the activated state, the actuator (48) engages directly or indirectly on the controller cylinder (14) such that the controller cylinder (14) is held in an intermediate position between two gears or between one gear and an idle position of the transmission (10). The invention further relates to a method for arresting a controller cylinder (14) of a sequential transmission (10) by means of such a device, comprising the following steps: rotating the controller cylinder (14) of the transmission (10) from a stable position into an intermediate position before the next stable position and arresting the controller cylinder (14) in the intermediate position by activating the actuator (48).