Rotary Servo Actuator Sensor Integration and Magnetic Shielding
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Solution Overview
Problem
Existing electromagnetic servo-actuators for valve actuation in internal combustion engines face issues with significant spatial size, sensor signal disturbance, and difficult indexing between the sensor and valve position, limiting their effectiveness and industrial applicability.
Innovation Solution
An integrated electromagnetic servo-actuator design where the sensor is seamlessly incorporated on the actuator's cylinder head, with a magnetic field transmitter secured to the yoke and a receiver located in a neutral plane relative to the stator poles, minimizing magnetic interference and allowing for precise position detection without affecting the sensor signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sensor is integrated on the actuator cylinder head, then the spatial requirements are reduced, but the sensor signal may be interfered with by the actuator's magnetic field
Solution Approach 1:
A magnetic shielding element is introduced as an intermediary between the actuator's magnetic field and the sensor. This shielding element, positioned in the magnetic field path, attenuates or blocks the harmful magnetic flux from reaching the sensor, thereby protecting the sensor signal while allowing the compact integrated design to be maintained.
Solution Approach 2:
The harmful magnetic field influence is extracted or separated from the sensor location by positioning the sensor in a region where the magnetic field is naturally weaker or by using magnetic shielding materials that extract and redirect the magnetic flux away from the sensor, thus eliminating the interference problem while maintaining integration.
2Measurement precision
If the sensor is positioned near the actuator poles, then the position detection precision is improved, but the magnetic field from the poles interferes with the sensor signal
Solution Approach 1:
A magnetic shielding structure is positioned between the actuator poles and the sensor to act as an intermediary that allows the sensor to remain close to the poles for high precision detection while blocking the harmful magnetic field from reaching the sensor, thus resolving the contradiction between proximity for precision and protection from interference.
3Device complexity
If the actuator and sensor are integrated in a compact design, then the device complexity is reduced, but the indexing between sensor and valve position becomes difficult
Solution Approach 1:
Indexing marks or reference features are preliminarily established during the manufacturing or assembly process of the integrated actuator-sensor unit. These pre-established reference features enable accurate alignment and indexing between the sensor and valve position without requiring complex adjustment procedures during installation or operation, thus maintaining both compactness and ease of indexing.
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 design reduces spatial requirements, prevents sensor signal interference, and enhances the actuator's thermal behavior, making it more suitable for industrial applications by providing a compact, reliable, and efficient means of determining the rotor's angular position.
Implementation Method 1
The magnetic field receiver is a Hall-effect magnetosensitive probe
Implementation Method 2
a stator structure with 2N poles, N being equal to 1 or 2, and at least one excitation coil, said stator structure being made of a material of high magnetic permeability, and a rotor having a ferromagnetic yoke
Data Source
Figure 1~2B
Figure 3~4
Figure 5~6
AI summary
The invention concerns a rotary single-phase electromagnetic servo actuator consisting of a rotary actuator designed to move a mobile member along a limited travel, including a 2N pole stator structure, N being equal to 1 or 2, and at least one field coil, said stator structure being made of a material with high magnetic permeability, and a rotor having a ferromagnetic yoke and a thin magnetized portion consisting of 2N pairs of axially magnetized poles, in alternate directions and a rotor angular position sensor. The invention is characterized in that the position sensor has a magnetic field emitter integral with the yoke and a receiver for the magnetic field stationary relative to the stator structure.