Transmission Actuator Magnet Guide for Precise Piston Position Sensing
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Solution Overview
Problem
Existing actuating devices for automated manual transmissions face challenges in maintaining precise alignment of magnetic-field-sensitive sensors with rotating pistons, leading to measurement inaccuracies due to potential rotational movements of the magnet during gear engagement.
Innovation Solution
Incorporation of a small anti-rotation element with a hollow cylindrical or hollow-cylinder-segment-shaped geometry, form-lockingly accommodated in the housing, which prevents rotational movement of the magnet while allowing axial and rotational movement of the piston, ensuring precise sensor alignment and reducing wear and manufacturing complexities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the magnet is arranged on the piston without anti-rotation mechanism, then the piston can rotate freely about the longitudinal central axis during gear engagement, but the magnet's rotational movement causes misalignment with the magnetic-field-sensitive sensor leading to measurement inaccuracies
Solution Approach 1:
The holding device is segmented into a cylindrical body that allows axial movement and a distinct anti-rotation element (such as a pin or key) that prevents rotational movement of the magnet. This segmentation enables the piston to move axially while keeping the magnet's angular position fixed relative to the sensor.
Solution Approach 2:
The anti-rotation element introduces asymmetry into the otherwise symmetric cylindrical holding device. This asymmetric feature (such as a keyway or pinned connection) selectively constrains rotational degrees of freedom while preserving axial movement freedom, thereby maintaining sensor alignment accuracy without compromising operational functionality.
2Measurement precision
If a rigid fixed connection is used between the magnet and housing, then the magnet's position is stable, but the piston cannot rotate or move axially freely during gear engagement
Solution Approach 1:
The holding device employs a dynamic connection mechanism that adapts to different movement requirements: it allows axial movement and rotation of the piston while maintaining fixed angular position of the magnet. The anti-rotation element dynamically permits axial displacement while preventing rotational displacement, achieving both stability and adaptability.
Solution Approach 2:
The holding device acts as an intermediary between the magnet and the piston assembly. It transmits axial movement from the piston to the magnet while blocking rotational movement, thereby mediating between the conflicting requirements of position stability and movement freedom through its specialized mechanical connection.
3Measurement precision
If complex anti-rotation mechanisms are implemented, then the magnet's rotational movement is prevented, but the device complexity and manufacturing costs increase
Solution Approach 1:
The anti-rotation element is implemented as a simple, inexpensive component such as a pin, key, or molded feature that can be easily manufactured and integrated into the holding device. This simple element provides effective anti-rotation functionality without requiring complex mechanisms, thereby maintaining measurement precision while minimizing device complexity and manufacturing cost.
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 solution ensures precise axial position measurement of the piston within the actuating device, enhances measurement accuracy, reduces wear, and simplifies manufacturing and integration, while maintaining low frictional forces and cost-effectiveness.
Implementation Method 1
a sensor system that includes a magnet and a magnetic-field-sensitive sensor is provided
Data Source
AI summary
An actuating device (10) for an automated manual transmission (12) includes a pressure-medium-operated actuator (54) having a piston (58) and a piston rod (64) connectable to the selector element or shift element of the manual transmission. The piston is arranged in a cylindrical receiving chamber (50) of the housing (18) of the actuator and is coaxially movable therein. A sensor system (30)includes a magnet (38) arranged on a holding device (44) and a magnetic-field-sensitive sensor (32) is arranged on the housing radially with respect to the magnet (44).The holding device has a hollow cylindrical geometry, an anti-rotation element (80)is form-lockingly accommodated in an associated recess in the housing (18), and that the anti-rotation element extends across the holding device in the manner of a secant such that rotational movement of the holding device is blocked, although axial and rotational movement of the piston are possible.