Rotary Reciprocating Actuator Layout for Noise-Free Angle Sensing
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Solution Overview
Problem
The rotary reciprocating drive actuator faces challenges in accurately detecting the rotational angle of the shaft due to shaft shake and electromagnetic noise interference, particularly when the angle sensor is not positioned near the bearing or is influenced by motor-generated heat.
Innovation Solution
The design includes a movable body with a magnet and a core assembly that generates a magnetic flux for reciprocating rotation, along with a sensor board for angle detection, positioned to avoid electromagnetic noise and heat sources, ensuring accurate angle sensing and high-amplitude driving capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the angle sensor is disposed close to the motor to detect rotational angle, then the detection function is integrated, but electromagnetic noise and heat generation from the motor interfere with sensor measurement
Solution Approach 1:
The actuator is divided into distinct functional zones: the motor assembly (core assembly with coil and magnet) is separated from the angle sensor assembly. The sensor is mounted on the case away from the motor, eliminating electromagnetic noise interference while maintaining detection functionality.
2Measurement precision
If the angle sensor is disposed away from the bearing to avoid shaft shake interference, then measurement accuracy improves, but the sensor positioning becomes more complex
Solution Approach 1:
A reference mark is introduced as an intermediary element. The reference mark is formed on the magnet, and the angle sensor detects the position of this reference mark to determine the rotational angle. This allows accurate measurement without the sensor being positioned near the bearing, as the reference mark moves with the magnet and provides a stable measurement target.
3Productivity
If high amplitude reciprocating rotation is achieved, then driving performance improves, but shaft shake increases affecting detection accuracy
Solution Approach 1:
The angle sensor is extracted from the motor assembly and mounted separately on the case. This separation removes the sensor from the source of vibration (shaft shake), allowing high amplitude reciprocating rotation to occur without compromising detection accuracy. The sensor detects the rotational angle through the reference mark on the magnet without being affected by mechanical vibrations.
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 configuration allows for precise detection of the shaft's rotation and improved driving performance by minimizing interference from shaft shake and electromagnetic noise, enabling high-amplitude operation of the movable object.
Implementation Method 1
a coil body that is wound around the core body and that is energized to generate a magnetic flux interacting with the magnet to cause a reciprocating rotation of the movable body
Implementation Method 2
a magnet position holding portion that generates a magnetic attraction force between the magnet position holding portion and the magnet to define a reference position of the reciprocating rotation
Data Source
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AI summary
A rotary reciprocating drive actuator includes: a movable body (10) including: a shaft part (13) to which a movable object (12) is connected at one end portion side of the shaft part (13), and a magnet (32) fixed at an other end portion side of the shaft part (13), the movable body (10) being capable of performing a reciprocating rotation about an axis; a base portion (21) including a pair of wall portions (211, 212) that are disposed to sandwich the movable object and support the shaft part (13) via a bearing at the one end portion side such that the shaft part (13) is rotatable; a core assembly (40) including: a core body (400) comprising a plurality of magnetic poles facing an outer circumference of the magnet (32) to sandwich the magnet (32), a coil body (49) that is wound around the core body (400) and that is energized to generate a magnetic flux interacting with the magnet (32) to cause a reciprocating rotation of the movable body, and a magnet position holding portion (48) that generates a magnetic attraction force between the magnet position holding portion (48) and the magnet (32) to define a reference position of the reciprocating rotation, the core assembly (40) being attached to one wall portion (211) of the pair of wall portions (211, 212); and a sensor board (72) that is attached to an other wall portion (212) of the pair of wall portions (211, 212) and on which a sensor (76) configured to detect a rotational angle of one end portion of the shaft part (13) is mounted, in which the sensor board (72) is disposed such that the sensor (76) faces the other wall portion (212) from an axially outer surface side of the other wall portion (212) and detects the rotational angle.