Electric Actuator Magnet Holder for Backlash-Free Position Detection

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing electric actuators face challenges in precise position detection due to backlash in link mechanisms, leading to increased size and complexity, which hinders series production and cost-effectiveness.

Innovation Solution

A sensor target with magnet holder and fitting claws is mounted to the movable part using snap fitting, allowing for backlash-free and non-contact position detection, reducing the number of parts and manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a link mechanism is used to detect the position of the movable part, then position detection precision is improved, but the number of parts increases and device size increases

Engineering Contradiction:
Improveposition detection precisionVSAvoidnumber of parts
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical link mechanism with a magnetic field-based detection system. A magnet is mounted on the movable part, and a magnetic sensor detects its position non-contactly, eliminating the need for mechanical link members and their associated joints, thereby reducing part count while maintaining detection precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnet as an intermediary carrier that transports position information from the movable part to the magnetic sensor without direct mechanical contact. This intermediary enables non-contact information transfer, avoiding the complexity of mechanical link mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If a link mechanism is used to detect the position of the movable part, then position detection precision is improved, but the size of the electric actuator increases

Engineering Contradiction:
Improveposition detection precisionVSAvoidsize of electric actuator
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The magnetic field-based detection system replaces the bulky mechanical link mechanism, significantly reducing the space required for position detection components. The magnet and magnetic sensor occupy minimal space compared to the link members and their mounting structures.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from a mechanical spatial linkage to a magnetic field interaction that operates in a different dimensional space, allowing position detection without occupying the same physical volume as mechanical link mechanisms.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If the sensor target is mounted using adhesive or screws, then mounting reliability is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvemounting reliabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The magnet holder performs multiple functions: it provides structural support for the magnet and simultaneously serves as the mounting interface through its elastic claws. The elastic deformation mechanism automatically achieves both secure attachment and positioning without requiring separate fastening operations.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent utilizes elastic deformation as a key parameter change mechanism. The elastic claws deform during mounting to engage with the movable part, providing both mechanical interlocking and positioning functionality, thereby achieving reliable mounting through material property utilization rather than complex assembly procedures.

Inventive Principle:
Principle #35Parameter changes

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 solution enables precise, simplified position detection of the actuator head, facilitating downsizing and cost-effective series production of electric actuators.

Implementation Method 1

one pair or a plurality of pairs of elastic claws capable of being fitted to an outer peripheral surface of the movable part are formed on the magnet holder

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the position of the magnet can be detected in the non-contact manner by the magnetic sensor

Methodology Applied
Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentEP3438506B1Electric actuator
Publication Date: 2023.10.11 NTN CORP
  • EP3438506B1 patent drawingFigure 1
  • EP3438506B1 patent drawingFigure 2
  • EP3438506B1 patent drawingFigure 3

AI summary

A sensor target of the present invention is mounted to a movable part (24), which is arranged in parallel with an output shaft (10a) of a motor (10), and is configured to perform a linear motion in a direction parallel to the output shaft (10a). The sensor target includes a magnet (73) and a magnet holder (74) configured to hold the magnet (73). One pair or a plurality of pairs of fitting claws (741) capable of being fitted to an outer peripheral surface of the movable part (24) are formed on the magnet holder (74).