Vehicle Transmission Shifting Device Axial Position Sensor
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Solution Overview
Problem
Conventional magnetic field sensors in vehicle transmission shifting devices struggle to accurately determine the relative position between the sensor and a target object in an axial direction, especially when the target object is rotational, leading to inefficiencies in establishing and releasing torque-proof connections between shifting element halves.
Innovation Solution
A shifting device with two positive-locking shifting element halves, where one half is axially displaceable and the other fixed, utilizing a magnetic field sensor with a ferromagnetic encoder contour that features monotonically increasing or decreasing surface areas to determine the operating states, and a differential amplifier to adjust signals for precise axial position measurement, allowing for efficient connection establishment and release regardless of rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional magnetic field sensors are used to detect the position of rotating gear wheels, then the sensors can detect rotational speed and position, but they cannot accurately determine the relative position in the axial direction regardless of whether the target object is rotational
Solution Approach 1:
The patent transitions from detecting radial/diametrical position (conventional magnetic field sensor application) to detecting axial position by using a ferromagnetic encoder contour with surface areas that extend in the axial direction. The encoder contour's surface area variation along the axial direction creates a magnetic field signature that corresponds to axial position, enabling the sensor to measure axial displacement of rotating components.
Solution Approach 2:
The patent changes the physical parameter being measured from radial position to axial position by designing the encoder contour with surface areas whose magnetic field influence varies monotonically with axial position. The ferromagnetic material's saturation behavior at different axial distances from the sensor creates a measurable parameter change that correlates to axial displacement.
2Measurement precision
If a ferromagnetic encoder contour with monotonically increasing or decreasing surface areas is used, then axial position can be determined accurately, but the device complexity increases due to the specialized sensor and encoder contour design
Solution Approach 1:
The patent combines the encoder contour and the sensor into a closely integrated assembly where the ferromagnetic encoder contour is positioned immediately adjacent to the magnetic field sensor. This merging eliminates the need for separate encoding mechanisms and reduces overall system complexity while maintaining measurement precision.
Solution Approach 2:
The patent replaces complex mechanical position sensing mechanisms with a magnetic field-based sensing system. The ferromagnetic encoder contour modulates the magnetic field according to axial position, and the magnetic field sensor detects these variations, substituting mechanical linkages and contacts with a non-contact magnetic sensing approach.
3Loss of information
If the encoder contour surface areas are designed to be monotonically increasing or decreasing in the axial direction, then the current operating state can be determined across the entire operating range, but the manufacturing precision requirements increase
Solution Approach 1:
The patent uses the monotonic variation of surface area in the axial direction to create a one-to-one correspondence between axial position and magnetic field strength. This parameter change ensures that each axial position produces a unique magnetic field signature, allowing the sensor to distinguish all operating states without requiring extremely precise manufacturing tolerances, as long as the monotonic relationship is maintained.
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 accurate and efficient determination of the current operating state of the shifting element halves across the entire operating range, ensuring reliable torque-proof connections with minimal effort, even when one or both shifting element halves rotate, by using a linear differential magnetic field sensor and a clamping module to limit offset voltages.
Implementation Method 1
a magnetic field sensor with a permanent magnet and a measuring device for sensing the magnetic field of the permanent magnet
Implementation Method 2
a ferromagnetic encoder contour that influences the magnetic field of the permanent magnet as a function of the operating states of the shifting element halves
Implementation Method 3
magnetic field variations, which are caused by the object moving through the magnetic field of a magnet of a magnetic field sensor, are determined through the magnetic field sensors
Data Source
AI summary
A shifting device with two positive-locking shifting element halves includes a positive connection between the shifting element halves that is able to be established or released. The respective prevailing operating states of the shifting element halves are determined through a sensor device. The surface areas of an encoder contour relative to a measuring device are formed in a convex or concave manner, whereas a perpendicular gap between the surface areas of the encoder contour and a permanent magnet, starting from a joint area between the surface areas in the direction of an end area of the surface areas increases or decreases in each case.