Encapsulated Magnetic Ball Switch for Tilt-Free Valve Position Sensing
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Solution Overview
Problem
Current valve position monitors for automatic transmissions are prone to erroneous position indications due to magnet tilt during longitudinal displacement, as the magnet attachment to the valve stem allows for tilting, leading to inaccurate valve position readings.
Innovation Solution
An encapsulated magnet position switch featuring a tubular body with multiple equally angularly positioned guide rails and a spherical magnetic ball, guided coaxially along the tubular body's axis, where a biasing member maintains the ball's position and sensors connected to a Hall effect switch accurately signal the ball's position, eliminating the need for a connector between the valve stem and magnet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a magnet is attached to a valve stem using a clip or fastener, then the magnet can be securely mounted, but the magnet may tilt during longitudinal displacement causing erroneous position indication
Solution Approach 1:
The system is divided into separate functional components: the valve stem, the magnetic ball, the guide rails, and the sensor assembly. The magnetic ball is separated from the valve stem connection, allowing independent optimization of each component - the stem can be securely fastened while the magnetic ball freely follows longitudinal motion without tilting.
Solution Approach 2:
The magnetic ball acts as an intermediary between the valve stem and the sensor. Instead of directly sensing the valve stem position, the sensor detects the magnetic ball's position, which is constrained to move only along the longitudinal axis by the guide rails, eliminating tilt-related measurement errors.
2Ease of manufacture
If a connector is used between the valve stem and magnet, then the magnet can be mounted on the stem, but the connector allows magnet tilt during displacement
Solution Approach 1:
The magnetic element is extracted from the traditional connector-based mounting system and replaced with a magnetic ball that moves independently within the tubular body. This eliminates the connector that causes tilting, while the magnetic field coupling maintains the functional connection between the valve stem and sensor.
Solution Approach 2:
The mechanical connector system is replaced with a magnetic field-based sensing system. The magnetic ball's position, constrained by guide rails, is detected by sensors (such as Hall effect sensors), replacing the need for direct mechanical coupling between the magnet and valve stem.
3Device complexity
If the magnet is allowed to move freely with the valve stem, then the position sensing is simplified, but the magnet tilt causes erroneous readings
Solution Approach 1:
A spherical magnetic ball is used instead of a traditional cylindrical or rectangular magnet. The spherical shape, combined with the guide rails, ensures that the magnetic element can move freely along the longitudinal axis while being constrained against tilting, as the sphere can only move along the path defined by the guide rails.
Solution Approach 2:
The magnetic element's degrees of freedom are changed from three-dimensional movement (allowing tilt) to one-dimensional movement along the longitudinal axis only. The guide rails constrain the magnetic ball's movement parameters, allowing free longitudinal displacement while preventing lateral and rotational movements that would cause tilting.
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 solution ensures accurate and reliable valve position sensing by minimizing the potential for axial misalignment and tilt, thereby providing precise valve position readings without the errors caused by traditional connector-based systems.
Implementation Method 1
Multiple sensors are positioned along the tubular body connected to a Hall effect switch, the sensors sensing and signaling a longitudinal position of the magnetic ball within the tubular body
Data Source
AI summary
An encapsulated magnet position switch includes a non-magnetic tubular body including a first end wall closing a first end of the tubular body and an oppositely positioned second end wall closing a second end of the tubular body. Multiple equally angularly spaced non-magnetic guide rails are connected to an inner wall of the tubular body between the first end wall and the second end wall. A spherical shaped magnetic ball is positioned within the tubular body and is retained between the first end wall and the second end wall. The magnetic ball is longitudinally guided by the multiple guide rails coaxial to a longitudinal axis of the tubular body. Multiple sensors are positioned along the tubular body and are connected to a Hall effect switch, the sensors sensing and signaling a longitudinal position of the magnetic ball within the tubular body.