Electric Valve Angle Sensing With a Permanent Magnet Shaft

Solution Overview

Problem

Existing electrically operated valves face challenges in accurately detecting the rotation angle of a rotating body due to the need for multiple magnetic sensors, which increases cost and complexity, and lose rotation angle information when power is turned off.

Innovation Solution

The electrically operated valve incorporates a permanent magnet member and an angle sensor positioned to detect the rotation angle of the magnet, allowing for accurate detection without multiple sensors and maintaining angle information even when power is off.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple magnetic sensors are disposed in the radially outer direction of the rotating body to detect rotation angle, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improverotation angle detection accuracyVSAvoidnumber of magnetic sensors

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/electrical Hall current-based angle detection system with a magnetic field-based detection system. A permanent magnet is fixed to the rotating body, and a magnetic sensor detects changes in magnetic flux density as the magnet rotates, converting mechanical rotation into magnetic field variations that can be measured and converted to rotation angle information.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from Hall current magnitude (which requires multiple sensors for accuracy) to magnetic flux density distribution (which can be detected by a single sensor through spatial variation). By detecting the spatial distribution of magnetic flux density around the permanent magnet, the system achieves accurate angle detection with fewer sensors.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If multiple magnetic sensors are disposed in the radially outer direction of the rotating body to detect rotation angle, then measurement precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improverotation angle detection accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical/electrical Hall current-based angle detection system with a magnetic field-based detection system. A permanent magnet is fixed to the rotating body, and a magnetic sensor detects changes in magnetic flux density as the magnet rotates, converting mechanical rotation into magnetic field variations that can be measured and converted to rotation angle information.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses the permanent magnet to create a replicated magnetic field pattern that mirrors the rotational position. The magnetic sensor detects this magnetic field copy, which contains all the angle information needed, eliminating the need for multiple physical sensors and reducing manufacturing costs.

Inventive Principle:

Principle #26Copying

3Ease of operation

If Hall current-based magnetic sensor detects rotation angle by increasing or decreasing current, then ease of operation is improved, but loss of information occurs when power is turned off

Engineering Contradiction:

Improvedetection operation simplicityVSAvoidrotation angle information retention

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The patent replaces the mechanical/electrical Hall current-based angle detection system with a magnetic field-based detection system. A permanent magnet is fixed to the rotating body, and a magnetic sensor detects changes in magnetic flux density as the magnet rotates, converting mechanical rotation into magnetic field variations that can be measured and converted to rotation angle information.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The permanent magnet continuously generates the magnetic field without requiring external power, enabling the system to retain its angle detection capability passively. The magnetic field persists as long as the magnet is in place, allowing the sensor to detect angle information at any time without power consumption for field generation.

Inventive Principle:

Principle #25Self-service

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

Accurate detection of the valve position is achieved with reduced complexity and cost, ensuring reliable operation and simplified structure.

Implementation Method 1

an angle sensor 80 which detects the rotation angle of the permanent magnet 72

Methodology Applied

Scientific EffectMagnetic flux density detection: Magnetic Field

Data Source

PatentEP4235106B1Electric valve

Publication Date: 2025.07.09 FUJIKOKI CORP

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AI summary

An object of the present invention is to provide an electrically operated valve capable of more accurately detecting the position of a valve body. [Resolution Means] In order to achieve the above object, the electrically operated valve of the present invention comprises a valve body, a driver configured to move the valve body along a first axis, a rotation shaft configured to rotate the driver around the first axis, a permanent magnet member, and an angle sensor. The permanent magnet member is disposed on the rotation shaft and configured to rotate with the rotation shaft. The angle sensor is configured to detect a rotation angle of a permanent magnet included in the permanent magnet member. The angle sensor is disposed above the permanent magnet.