Hybrid Shift Drum Referencing Without Mechanical End Stops
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Solution Overview
Problem
Existing shift drum assemblies in hybrid drive trains are limited by physical end stops, restricting the maximum rotational capability to less than 360°, which is inadequate for systems requiring endless rotation in both directions.
Innovation Solution
A method is developed to determine virtual end stops on an endlessly rotatable shift drum by generating differential speeds using an electric machine, braking it to zero at specific switching elements to assign speed signals as reference positions, allowing for precise angular positioning without mechanical constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical end stops are integrated into the shift drum assembly, then the shift drum's rotational position can be referenced, but the maximum rotational capability is limited to less than 360°
Solution Approach 1:
The patent replaces the mechanical end stop system with an electronic/reference-based system. Instead of using physical stops that mechanically limit rotation, the invention uses a reference element (such as a magnetic element or sensor) that detects angular position electronically, allowing the shift drum to rotate more than 360° while still providing precise positional reference through sensor signals rather than mechanical constraints.
Solution Approach 2:
The invention changes the parameter of rotational limitation from a fixed mechanical constraint (physical end stops preventing rotation beyond certain angles) to a flexible electronic reference system. By using angular position sensors and reference elements that can detect position at any rotation angle, the system allows continuous rotation while maintaining precise positional awareness through electrical parameters rather than mechanical boundaries.
2Adaptability or versatility
If a shift drum is designed to rotate endlessly in both directions, then flexibility for hybrid drive train operations is enhanced, but determining reference positions becomes more complex
Solution Approach 1:
The patent introduces a reference element as an intermediary between the shift drum and the control system. This reference element (such as a magnetic marker or optical indicator) provides a detectable signal that serves as a reference position marker. The intermediary translates the mechanical rotation into an electrical or optical signal that the control unit can process, simplifying the determination of reference positions even when the drum rotates endlessly in both directions.
Solution Approach 2:
The invention replaces complex mechanical reference determination mechanisms with electronic sensing systems. Instead of using mechanical stops or physical markers that require complex mechanical detection, the patent uses sensors (such as magnetic sensors or optical detectors) that electronically identify reference positions based on signals from reference elements, significantly reducing the complexity of the reference determination system while enabling endless rotation.
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
Enables precise determination of shift angles on a shift drum that can rotate endlessly in both directions, overcoming the limitations of physical end stops and enhancing the flexibility and efficiency of hybrid drive train operations.
Implementation Method 1
a small speed is generated by means of the electric machine, whereby a differential speed is created at at least two switching elements of the transmission arrangement
Implementation Method 2
a first switching element is switched at the differential speed, so that the electric machine is suddenly braked to zero, wherein a speed signal of the electric machine is generated
Data Source
Figure 1
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AI summary
The invention relates to a method for teaching-in a gear shift drum (100) in a hybrid drive train (10), wherein the hybrid drive train (10) comprises a first drive machine in the form of an internal combustion engine (12) and a second drive machine in the form of an electric machine (16), as well as a transmission assembly (18) which can be connected to the first drive machine (12) via a switch element (K0), and is/can be connected to the second drive machine (16), wherein the transmission assembly (18) comprises an input shaft (26) and an output shaft (34) and a plurality of gear stages (40, 46, 56) arranged in between, which are designed such that they can be switched via associated switch elements (K1, K2, K3), wherein the switch elements (K0, K1, K2, K4) are switched via a gear shift drum (100) that can be rotated about 360 degrees, comprising the steps of: rotating the gear shift drum (100) into a first switch state which corresponds to a neutral position of the transmission assembly (18); generating a low rotational speed by means of the electric machine (16), producing a differential speed at at least two switch elements (K0, K2) of the transmission assembly (18); rotating the gear shift drum (100) in a first rotational direction into a second switch state, wherein a first switch element (K0) is switched with the differential speed, such that the electric machine (16) is abruptly decelerated to zero, wherein a rotational speed signal of the electric machine (16) is generated and this rotational speed signal is assigned to a first reference position/reference angle as a virtual end stop; rotating back the gear shift drum (100) into the first switch position and rotating the gear shift drum (10) in the second rotational direction into another switch state, wherein a second switch element (K2) is switched with the differential speed, such that the electric machine (16) is abruptly decelerated to zero, wherein a rotational speed signal of the electric machine (16) is generated and this rotational speed signal is assigned to a second reference position/rotational angle as a virtual end stop.