Inductive Rotation Angle Sensor Shielding for Airflow Control
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Solution Overview
Problem
Conventional non-contact rotation angle sensors for motor-driven airflow control devices are bulky and prone to reliability issues due to exposure to moisture and chemicals, leading to electromagnetic degradation and reduced detection accuracy.
Innovation Solution
A compact inductance-based rotation angle sensor design featuring an exciting conductor on a rotating shaft with energizing and signal-generating conductors on a stationary substrate, shielded by a thin member to protect from environmental factors, allowing for precise position detection without increasing clearance between components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic disc and a conductor disc are provided between two detection coils on a stator, then rotation angle detection is achieved, but the apparatus becomes large in size
Solution Approach 1:
The patent extracts the conductor disc from the conventional configuration and replaces it with a conductor attached directly to the rotating shaft. This eliminates the need for a separate conductor disc, reducing the number of components and overall sensor size while maintaining rotation angle detection capability through inductance variation between the stator coil and the shaft-mounted conductor.
Solution Approach 2:
The patent merges the function of the conductor disc with the rotating shaft by directly attaching the conductor to the shaft. This consolidation reduces the number of separate components (magnetic disc, conductor disc, stator coil) to a simpler configuration (stator coil, shaft-mounted conductor), thereby reducing sensor size while preserving detection functionality.
2Measurement precision
If the rotation angle sensor is mounted on a motor-driven airflow control device, then rotational position detection is achieved, but the substrate with electronic components is exposed to moisture, chemicals, and abrasion powder causing oxidization, corrosion, or electromagnetic degradation
Solution Approach 1:
The patent extracts the substrate with electronic components from the environment exposed to moisture, chemicals, and abrasion powder. By mounting the substrate on the stator side (away from the air intake passage) and using a non-contact inductance-based detection method, the electronic components are isolated from harmful environmental factors while maintaining rotational position detection capability through electromagnetic induction.
Solution Approach 2:
The patent uses electromagnetic induction as an intermediary mechanism to transmit rotational position information from the rotating conductor to the stationary stator coil without direct contact. This non-contact detection method allows the substrate to remain isolated from the harsh environment (moisture, chemicals, abrasion powder) while still achieving accurate rotational position measurement.
3Ease of manufacture
If the clearance between a rotating conductor and a substrate having the coils on the stationary side increases, then assembly tolerance is improved, but electromagnetic induction decreases causing degradation of position detection accuracy
Solution Approach 1:
The patent optimizes the clearance parameter between the rotating conductor and the stator coil to achieve an optimal balance between assembly tolerance and detection accuracy. By carefully controlling this dimensional parameter, the design allows for practical assembly variations while maintaining sufficient electromagnetic induction for accurate position detection.
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 provides a compact, reliable, and accurate rotation angle sensor that is resistant to environmental conditions, ensuring consistent performance in motor-driven airflow control devices.
Implementation Method 1
energizing conductors which are attached to a stationary substrate provided in proximity to the rotary member, to excite a current in the exciting conductor in electromagnetic cooperation with the exciting conductor
Implementation Method 2
signal-generating conductors which are attached to the stationary substrate together with the energizing conductors, in which alternating-current signals are induced by the current generated in the exciting conductor
Data Source
AI summary
A motor-driven airflow control device is provided wherein an inductance-based non-contact rotation angle sensor is compactly formed at an end of a throttle shaft. An exciting conductor is attached at an end of a rotating shaft to which a throttle valve is attached, a window hole is provided on a gear cover, a stationary substrate with energizing and signal-generating conductors formed thereon is attached to the gear cover so as to face the exciting conductor on the rotating shaft side through the window hole, and the window hole of the gear cover is covered by a thin shield member. The energizing and signal-generating conductors can be shielded from a space where the exciting conductor of the rotary member is arranged, making it possible to obtain a highly reliable motor-driven airflow control device including an inductance-based non-contact rotation angle sensor which is not affected by environments on the rotary member side.