Valve Position Feedback via Thermally Decoupled Magnet
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Solution Overview
Problem
Existing valve devices for internal combustion engines, such as exhaust gas recirculation valves, face challenges in providing precise and reliable position feedback over a long period, especially under thermal stress, due to magnet demagnetization and sensor inaccuracies caused by environmental and thermal factors.
Innovation Solution
A valve device design featuring a carrier element with a magnet interacting with a non-contact sensor injected into the housing, where the sensor is thermally decoupled from the adjustment element and secured within the housing to prevent detachment, using an axially magnetized permanent magnet and a heat-insulating ceramic element to enhance durability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnet is arranged on the adjustment element for position feedback, then position feedback is enabled, but the magnet is exposed to high thermal loads causing demagnetization and limited service life
Solution Approach 1:
The system is divided into a hot section (adjustment element in exhaust gas area) and a cold section (sensor housing). The magnet is thermally decoupled from the adjustment element through this segmentation, allowing position feedback while protecting the magnet from thermal loads.
Solution Approach 2:
A carrier element acts as an intermediary between the adjustment element and the magnet. This intermediary transfers the positional information to the magnet without directly exposing the magnet to the thermal environment of the adjustment element.
2Measurement precision
If a sensor is arranged in the exhaust gas area for position feedback, then position monitoring is achieved, but the sensor is exposed to environmental influences reducing reliability
Solution Approach 1:
The sensor is extracted from the harsh exhaust gas environment and placed in a protected housing. This extraction maintains the ability to monitor position through the magnet while removing the sensor from direct exposure to damaging environmental conditions.
Solution Approach 2:
The sensor housing acts as a protective shell that shields the sensor from environmental influences. This enclosure provides mechanical protection and thermal isolation while allowing the magnetic field to pass through for position detection.
3Reliability
If additional components are added for thermal decoupling and sensor protection, then reliability improves, but device complexity increases
Solution Approach 1:
The carrier element combines multiple functions: it mechanically connects to the adjustment element, provides the mounting structure for the magnet, and acts as part of the thermal decoupling system. This merging reduces the number of separate components needed.
Solution Approach 2:
The housing serves multiple purposes: it protects the sensor from environmental influences, provides structural support, enables thermal decoupling, and facilitates sensor mounting. This multi-functionality reduces overall system complexity despite adding protection features.
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
Ensures precise and reliable position feedback over a long service life without additional installation space or assembly effort, with the magnetic sensor unit being easy to integrate and produce inexpensively, while maintaining accuracy under high thermal loads.
Implementation Method 1
a magnet is attached, which interacts with a non-contact sensor
Implementation Method 2
a heat-insulating ceramic element to enhance durability and accuracy
Data Source
Figure 1~2
AI summary
Valve devices are known which have a drive unit, a gearing and a downstream coupling element for converting a rotational movement of the drive unit into a translatory movement of an adjusting element. In the case of said elements, position feedback takes place, in particular under high thermal loading, usually by virtue of the rotational position of a gearing part being detected. To achieve correct position detection in such a valve device, it is proposed that a carrier element (36) be rigidly arranged on the coupling element (8), to which carrier element a magnet (40) is fastened which interacts with a contactless sensor (42) fastened in the housing (10).