Actuator Encoder Disk Nested Between Rotor Bearings
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Solution Overview
Problem
Existing electrical actuators with position encoders face challenges in compactness, reliability, and cost-effectiveness, particularly in applications where height is a concern, such as in stacked hydraulic valve systems, due to the separate mounting of encoder disks which increases the motor's height and complexity.
Innovation Solution
An electrical actuator design where the encoder disk is positioned around the rotor shaft between the rotor bearings, with a center support portion offset in the axial direction, allowing the encoder disk to be mounted internally and reducing the overall height while maintaining high resolution and easy signal reading through magnetic or optical sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an encoder disk is mounted externally to the motor, then position sensing accuracy is improved, but the actuator height increases
Solution Approach 1:
The encoder disk is nested within the motor structure by positioning it between the rotor body and rotor bearing, with the center support portion offset axially to allow the rotor bearing to be positioned at least partially within the offset. This nesting approach integrates the encoder into the existing motor geometry without adding external height.
Solution Approach 2:
The encoder disk is positioned in the radial dimension around the shaft rather than extending in the axial dimension, and the center support portion is offset in the axial direction to create space within the existing axial envelope. This dimensional repositioning allows the encoder to function without increasing overall actuator height.
2Length of moving object
If the encoder disk is positioned offset from the rotor axis in a gear, then actuator height is reduced, but device complexity increases
Solution Approach 1:
The encoder disk is merged with the rotor assembly by mounting it directly to the rotor shaft, and the rotor bearing is integrated into the encoder structure by positioning it within the offset center support portion. This merging eliminates the need for separate gear mechanisms while maintaining compact dimensions.
3Length of moving object
If the encoder disk is positioned offset from the rotor axis, then actuator height is reduced, but encoder resolution decreases
Solution Approach 1:
The encoder disk is pre-positioned on the rotor shaft with its rim positioned adjacent to the rotor body, and the center support portion is pre-offset axially to create the bearing space. This preliminary positioning ensures optimal encoder resolution is maintained while enabling the compact configuration.
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 achieves a compact, reliable, and cost-effective actuator with high resolution position sensing, enabling accurate control of hydraulic valve systems by minimizing the actuator's height and maintaining encoder resolution, thus facilitating the stacking of actuators in hydraulic systems.
Implementation Method 1
maintaining encoder resolution, thus facilitating the stacking of actuators in hydraulic systems
Implementation Method 2
maintaining encoder resolution, thus facilitating the stacking of actuators in hydraulic systems
Data Source
Figure 1
Figure 2
AI summary
Electrical actuator (2) comprising a housing (4), a signal processing circuit (6), an encoder disk (26), and a motor (8) comprising a stator (20) with electric coils (38) and a rotor (22) comprising a rotor body (42) and shaft (40) rotatably supported by rotor bearings (24a, 24b). The encoder disk is positioned around the shaft adjacent the rotor body and sandwiched between one of the rotor bearings (24b) and the rotor body.