Hybrid Transmission Shift Drum Referencing for Endless Rotation
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Solution Overview
Problem
Existing switching devices for hybrid drive trains, such as those with shift drums, face limitations in achieving endless rotation due to the constraints imposed by fixed end stops, which restrict the maximum rotation angle and increase costs with the use of absolute sensors for referencing the twist angle.
Innovation Solution
A switching device with a stop device comprising a shift stop connected to a second shift rod and an end stop on the second shift drum, allowing endless rotation by activating the stop only when necessary, enabling a total shift angle of 360 degrees through axial displacement and forced coupling of the shift rods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed end stop is permanently connected to the shift drum body, then the rotational position can be referenced, but the maximum rotation angle is limited to less than 360 degrees
Solution Approach 1:
The stop device is designed to be axially displaceable relative to the shift drum body, transitioning between an active state (where the stop element engages the housing stop to reference rotational position) and an inactive state (where the stop device is axially displaced away, allowing endless rotation). This dynamic configuration resolves the contradiction by making the rotational constraint conditional rather than permanent.
Solution Approach 2:
The stop device is separated from the shift drum body through axial displacement capability, allowing the stop element to be independently positioned. This segmentation enables the stop element to engage for referencing when needed, while allowing the shift drum to rotate freely when the stop device is displaced, thus achieving both precise positioning and extended rotation range.
2Measurement precision
If a stop element and housing stop are used to reference rotational position, then the shift angle can be referenced, but the available rotation angle is reduced due to the circumferential space occupied by the stops
Solution Approach 1:
The stop device can be axially displaced to an inactive position where it does not constrain the shift drum rotation. This dynamic behavior allows the system to achieve full 360-degree or greater rotation when referencing is not needed, while still providing precise angle reference when the stop device is in its active engaged state.
Solution Approach 2:
The stop device operates periodically, engaging to reference the shift angle at specific moments in the rotation cycle, then disengaging to allow continuous rotation. This periodic engagement provides sufficient referencing capability without permanently limiting the rotation range, maximizing the available rotation angle for gear switching operations.
3Measurement precision
If absolute sensors are used to reference the rotational position of the shift drum, then the rotational position can be accurately determined, but the costs increase significantly
Solution Approach 1:
The invention replaces expensive absolute sensors with a simple mechanical stop element and housing stop configuration that provides sufficient rotational position reference at minimal cost. The stop device uses basic mechanical components rather than sophisticated electronic sensing systems, dramatically reducing manufacturing costs while maintaining adequate measurement precision for transmission gear referencing.
Solution Approach 2:
The stop device utilizes the existing structural components of the transmission housing and shift drum assembly to create the referencing mechanism, rather than requiring separate expensive sensing systems. The mechanical interaction between the stop element and housing stop provides self-contained positional reference using the system's own structural elements.
Data Source
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AI summary
The invention relates to a shifting device (40) of a transmission unit, more particularly of a hybrid drive train for motor vehicles, comprising: - a first shifting drum (50), the shifting drum (50) being rotatable about a shifting-drum axis and having a shifting contour (55) running on the periphery of the outer surface, the shifting contour being formed in an axial and/or radial direction; - a driver element (54), which interlockingly engages in the shifting contour; - a second shifting rod (52), which is coupled to the driver element in such a way that an axial movement of the driver element (54) likewise causes an axial movement of the shifting rod (52), the second shifting rod (52) comprising a selector element/selector fork (53) for selecting the gears associated with the shifting contour of the first shifting drum (50); - a second shifting drum (60), the shifting drum (60) being endlessly rotatable about a shifting-drum axis and having at least one peripheral shifting contour running on the periphery of the outer surface, the at least one shifting contour being formed in an axial and/or radial direction; - a stop apparatus (70) for referencing a shifting angle of the second shifting drum (60) in a reference angle position, the stop apparatus (70) comprising a shifting stop (71), which, with the first shifting drum (50) in a predefined shifting angle/shifting angle range, can be activated into an activation position such that the rotation of the second shifting drum (60) is blocked in the reference angle position.