Bottom-Bracket Gearbox With Nested Shift Actuator
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Solution Overview
Problem
Existing bottom bracket gearboxes in micromobility vehicles require significant axial installation space for actuating the shift drum, which can lead to increased gearbox housing width and reduced compactness.
Innovation Solution
A bottom bracket gearbox design featuring a hollow shift drum with an integrated electro-mechanical shift actuator, which is coaxially arranged with the shift drum, reducing the axial width requirement and allowing for a more compact gearbox housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional shift actuator arrangement is used for actuating the shift drum, then the shift drum can be actuated, but the axial installation space required in the gearbox housing increases
Solution Approach 1:
The shift actuator is arranged in the interior of the shift drum, which is formed as a hollow shaft. The actuator unit is at least partly arranged radially inside, or radially nested, in the shift drum, allowing the actuator to be contained within the existing shift drum volume rather than requiring additional axial space outside the drum.
Solution Approach 2:
The invention transitions from an axial arrangement where the actuator would be positioned along the axial direction to a radial arrangement where the actuator is positioned within the radial interior of the hollow shift drum. This dimensional change from axial to radial placement eliminates the need for additional axial installation space.
2Length of stationary object
If the axial width of the gearbox housing is reduced for compactness, then the overall vehicle size decreases, but the shift drum actuation becomes difficult to implement
Solution Approach 1:
By nesting the shift actuator within the hollow interior of the shift drum, the design eliminates the need for additional axial space that would traditionally be required for actuator mounting, thereby maintaining compact gearbox housing dimensions while enabling shift drum actuation.
Solution Approach 2:
The invention combines the shift drum and shift actuator into a single integrated assembly where the actuator is housed within the drum structure. This merging of components allows the actuation mechanism to be implemented without increasing the overall axial width of the gearbox housing.
3Length of stationary object
If a hollow shift drum with integrated actuator is used, then axial installation space is reduced, but the structural complexity of the shift drum increases
Solution Approach 1:
The hollow shift drum structure is designed to contain the actuator unit within its interior volume. This nesting approach allows the complex actuator mechanism to be housed within the drum without requiring additional external components or increasing axial space, as the drum structure itself serves as the housing for the actuator.
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
The design achieves a structurally simple and installation space-neutral actuation of the shift drum, maintaining the compactness of the gearbox housing and optimizing torque transmission and support.
Implementation Method 1
an input pinion of the shift actuator, which input pinion is in engagement with inner toothing, or the like, as an entrainment profile in the interior of the shift drum
Implementation Method 2
the electro-mechanical shift actuator has, in addition to an electric motor or servomotor, or the like, an integrated reduction gear
Implementation Method 3
each shift element having a shift ring with an outer toothing or the like, the shift ring being assigned a shift pawl for locking and releasing the shift ring of the shift element
Data Source
AI summary
A bottom bracket gearbox for a micromobility vehicle (1) includes at least one shift element. Each shift element includes a shift ring (3) with an outer toothing (4). The shift ring assigned a shift pawl (5) for locking or releasing the shift ring (3) of the shift element. The shift ring being assigned to a gearbox component. At least one rotatably mounted shift drum (7) for actuating the assigned shift pawl (5) is axially parallel to a central axis of rotation of the gearbox (6). A shift actuator (8) is arranged in the interior of the shift drum (7), which is formed, at least partially or in sections, as a hollow shaft.