Parking Locking Unit with Guided Magnetic Position Sensing
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Solution Overview
Problem
Existing locking units for automatic transmission parking locks lack reliable monitoring capabilities, particularly in maintaining the locking position during vehicle operation and standstill, and are prone to positional offsets due to vibrations, which affect measurement accuracy.
Innovation Solution
A locking unit with a hydraulically actuated piston, an electromagnet, a magnetic element, and a biasing element, where the magnetic element is guided in a tube to minimize radial play and ensure accurate positional sensing, and an anti-rotation device prevents measurement distortion from unwanted rotations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic element is provided to sense the position of the armature or armature rod, then monitoring capability is improved, but measurement accuracy deteriorates due to positional offsets caused by vibrations
Solution Approach 1:
A non-magnetic guide tube is introduced as an intermediary component to constrain the magnetic element's movement. The guide tube provides a defined linear path for the magnetic element, preventing lateral displacements and rotations caused by vibrations, thereby maintaining measurement accuracy while enabling monitoring capability
Solution Approach 2:
The magnetic element is preloaded axially against the armature or armature rod, creating a constant contact force. This preload ensures that the magnetic element maintains a stable, defined position relative to the sensor, eliminating play and ensuring accurate position measurement even under vibrational conditions
2Reliability
If the magnetic element is allowed to move freely to track armature position, then monitoring capability is improved, but measurement precision deteriorates due to radial play and undefined positional displacement
Solution Approach 1:
The guide tube provides localized constraint only in the radial direction, allowing the magnetic element to move freely axially to track armature position while preventing lateral displacements. This selective constraint maintains monitoring capability while ensuring measurement precision
Solution Approach 2:
The guide tube acts as an intermediary constraint structure that mediates between the need for free axial movement (for position tracking) and the need to prevent radial play (for measurement accuracy). The tube's internal geometry provides the necessary guidance without restricting the magnetic element's primary movement function
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 reliable monitoring and maintenance of the locking position, preventing positional offsets and ensuring accurate measurement of the anchor and anchor rod position, even under vibrations, thus enhancing the locking unit's reliability and accuracy.
Implementation Method 1
The electromagnet 20 has a coil 22, which is arranged radially outside an armature 24. A magnetic field generated by the coil 22 can typically actuate the armature in two directions in one dimension.
Implementation Method 2
The magnetic element 70 generates a magnetic field which is detected by a detector or another magnetic field-detecting element, whereby the signals generated can typically be evaluated electronically to provide information about the condition of the armature and/or the armature rod.
Data Source
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AI summary
The invention relates to a locking unit comprising a hydraulically actuated piston, an electromagnet with a coil and an armature, at least one detent element, a connecting rod, and a magnetic element, wherein the connecting rod links the magnetic element to the armature or an armature rod attached thereto, and a preload element radially fixes the magnetic element in a guide tube. This enables advantageous position determination by sensing a magnetic field generated by the magnetic element.