Friction Clutch Actuator Piston Position Detection
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Solution Overview
Problem
Existing actuators for friction clutches, such as master and slave cylinders, face challenges in reliably detecting the position of the piston over large travel distances due to insufficient magnetic flux density provided by single magnets.
Innovation Solution
The actuator employs two radially opposed magnets, with a Hall sensor measuring the magnetic field generated by these magnets, which are positioned orthogonally to the piston's movement direction, ensuring high magnetic flux density and linearity over extended piston travel, and allows for adjustable distance between the magnets to accommodate varying movement requirements without additional magnetic material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnet is used in the actuator, then the device complexity is reduced, but the magnetic flux density becomes insufficient for large piston adjustment travels
Solution Approach 1:
The single magnet is divided into multiple magnets (first magnet and second magnet) arranged at different radial positions on the piston. Each magnet contributes to the overall magnetic flux density, allowing the system to achieve sufficient measurement precision across large piston adjustment travels while keeping individual magnets of manageable size and strength.
2Volume of stationary object
If magnets are placed closer together to maintain compact size, then the device volume is reduced, but the magnetic field linearity deteriorates over large travel distances
Solution Approach 1:
Magnets are positioned at specific radial locations on the piston where they generate optimized magnetic field contributions. The Hall sensor is strategically placed to detect the combined magnetic flux from multiple magnets, ensuring high linearity of the magnetic field signal across the full range of piston travel while maintaining a compact actuator design.
3Measurement precision
If additional magnetic material is added to increase flux density, then the magnetic flux density improves, but the manufacturing cost and device complexity increase
Solution Approach 1:
Instead of increasing the size or strength of individual magnets in one dimension, the solution adds magnets in a different spatial dimension (radial arrangement around the piston). This multi-dimensional magnetic field configuration achieves sufficient flux density for large piston travels without requiring additional magnetic material beyond what is already distributed across multiple smaller magnets.
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
This configuration enables reliable detection of piston position over large distances with high magnetic flux density and improved linearity, reducing the need for additional magnetic material and variants, thus lowering costs while enhancing positional accuracy.
Implementation Method 1
a Hall sensor for measuring a magnetic field of the first magnet and second magnet being arranged on the housing
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~4c
AI summary
The invention relates to an actuator (1) for actuating a friction clutch, comprising a housing (2) and a piston (3) that can be moved in the housing, wherein at least a first magnet (4) and a second magnet (5) are fastened to the piston, which magnets are spaced apart from each other in a direction of motion of the piston and are magnetized in opposite directions, and wherein a Hall sensor (7) for measuring at least a magnetic field of the first magnet and of the second magnet is arranged on the housing.