Rotary Reduction Actuator Output-Angle Sensing Against Gear Backlash

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional rotary reduction actuators face challenges in accurately detecting the rotational position of the output shaft due to backlash and rotational displacement differences during transmission, leading to inaccurate position control.

Innovation Solution

A rotary reduction actuator with a rotational position detection function that includes a drive shaft, reduction gear unit, and a rotational angle sensing unit, featuring an interlocking structure with sensing gears and a sensing magnet to accurately measure rotational displacement at the output end.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the position detection unit is located at the input end of the motor, then the structure is simple, but accurate position control with respect to the output shaft cannot be achieved

Engineering Contradiction:

Improvestructure simplicityVSAvoidoutput shaft position detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

A rotational angle sensing unit is introduced as an intermediary component between the reduction gear unit and the position detection unit. This sensing unit includes a detection gear that meshes with the reduction gear's output gear, a magnet attached to the detection gear, and a sensor that detects the magnet's position. This intermediary mechanism transmits rotational position information from the output shaft to the detection system, enabling accurate output shaft position detection while maintaining overall system simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the position detection unit is located at the input end of the motor, then the detection structure is simple, but rotational displacement measurement is inaccurate due to backlash

Engineering Contradiction:

Improvedetection structure simplicityVSAvoidrotational displacement measurement accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The rotational angle sensing unit acts as an intermediary that directly measures rotational displacement at the reduction gear output without being affected by backlash in the motor-to-reduction transmission path. The detection gear meshes with the reduction gear's output gear, ensuring that the magnet's position accurately reflects the output shaft's rotational position, thereby eliminating measurement errors caused by upstream backlash.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention replaces direct mechanical coupling-based position detection with a magnetic field-based detection system. Instead of relying on mechanical position sensors directly on the motor shaft, a magnet is attached to the detection gear and detected by a magnetic sensor, substituting mechanical transmission of position information with magnetic field sensing, which is more accurate and不受backlash影响.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If the position detection unit is located at the input end of the motor, then the system configuration is simple, but position control reliability is poor

Engineering Contradiction:

Improvesystem configuration simplicityVSAvoidposition control reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The rotational angle sensing unit provides real-time feedback on the output shaft's rotational position by detecting the magnet's position as the detection gear rotates with the reduction gear output. This feedback mechanism enables the control system to accurately monitor and adjust the output shaft position, significantly improving position control reliability compared to indirect detection methods that cannot account for transmission errors.

Inventive Principle:

Principle #23Feedback

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

Enables precise measurement of rotational displacement and position estimation of the output shaft, enhancing control reliability and robustness, particularly in applications like electronic shift lever systems.

Implementation Method 1

a rotational angle detection sensor configured to detect rotational displacement of the sensing magnet

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentEP4703605A1Rotary reduction actuator having rotational position detection function, and electronic shift lever system employing same

Publication Date: 2026.03.04 PYONG HWA VALEO

Figure 1
Figure 2
Figure 3

AI summary

The present invention relates to a rotary reduction actuator capable of more accurately detecting a rotational position of an actuator output shaft by detecting a rotational position of the actuator at an output end of a reduction gear unit, thereby improving reliability and robustness of shift control. The rotary reduction actuator includes a drive shaft installed on an output side of an electric motor, a reduction gear unit configured to reduce and output rotation of the drive shaft, and a rotational angle sensing unit configured to detect rotational displacement of the output end of the reduction gear unit. The rotational angle sensing unit includes an interlocking structure interlocked with the output end of the reduction gear unit, a sensing magnet installed to operate in interlocking relation with operation of the interlocking structure, and a rotational angle detection sensor configured to detect rotational displacement of the sensing magnet.