Rotary Reciprocating Actuator Preload Structure for Bearing Stability
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Solution Overview
Problem
Conventional rotary reciprocating drive actuators, such as those used in optical scanning apparatuses, face challenges in achieving high rotational accuracy and stability due to the rigidity of the rotation shaft and sliding issues between the shaft and bearings.
Innovation Solution
A configuration that includes a shaft with a magnet, a core assembly with magnetic poles, a coil, and a preload applying part to enhance the magnetic attraction force and reduce sliding, improving the rotational accuracy and reliability of the actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rotation shaft is made more rigid to improve rotational accuracy, then rotational accuracy is improved, but sliding between the shaft and bearings increases
Solution Approach 1:
The patent changes the physical state of the bearing support system by introducing a preload force that shifts the operating conditions of the bearings. This preload ensures continuous contact between the shaft and bearing raceways, transforming the bearing operation from a state with periodic separation to one with sustained engagement, thereby eliminating sliding while maintaining rigidity
Solution Approach 2:
The patent applies a preliminary preload force to the bearings before the actuator begins its operational cycle. This preliminary action of pre-compressing the bearing assemblies ensures that the shaft and bearings are already in optimal contact position, preventing any sliding or loss of contact during subsequent rotational operations
2Device complexity
If conventional bearing support is used without preload, then device complexity is reduced, but rotational accuracy and driving stability deteriorate
Solution Approach 1:
The preload applying mechanism serves multiple functions simultaneously: it preloads the bearings to eliminate sliding, positions the shaft with high precision, and maintains continuous contact during reciprocating rotation. This multi-functionality achieves high rotational accuracy without proportionally increasing device complexity
Solution Approach 2:
The patent introduces a preload applying mechanism as an intermediary element between the bearing support structure and the rotation shaft. This intermediary component applies the necessary preload force without requiring complex modifications to either the bearings or the shaft, achieving improved rotational accuracy through a dedicated intermediate device
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 proposed solution enhances the rotational accuracy and reliability of the actuator by improving the shaft's rigidity and reducing sliding, enabling more stable and precise rotary reciprocating drive operations.
Implementation Method 1
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
Implementation Method 2
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
Data Source
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AI summary
A rotary reciprocating drive actuator (1) includes: a movable body (10) including a shaft part (13) to which a magnet (32) is fixed at an outer circumference of the shaft part and being capable of performing a reciprocating rotation around an axis; a base portion (21) including a pair of wall portions (211, 212) for supporting the shaft part (13) via a bearing (22) such that the shaft part is rotatable; a core assembly (40) including: a core body (400) having a plurality of magnetic poles (410a, 410b) 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 (10), and a magnet position holding portion (48) that generates a magnetic attraction force between the magnet position holding portion and the magnet (32) to define a reference position of the reciprocating rotation; and a preload applying part (35) that is externally fitted to the shaft part (13) and is configured to apply a preload to the bearing (22).