Curved Rotor Convex Concave Portions for Rotation Angle Detection

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Solution Overview

Problem

Existing rotation detection devices face challenges in accurately detecting rotation angles due to the use of rectangular-shaped protrusions and recesses, which do not change smoothly and periodically, limiting the precision of magnetic field changes detection.

Innovation Solution

A rotation angle detection device featuring a rotor with convex and concave portions that change in a curved, sine wave manner, paired with a stator containing multiple magnetic detection elements and a bias magnetic field generation portion, allowing for precise detection of magnetic field changes across a rotor's surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If rectangular-shaped protrusions and recesses are formed on the rotor, then the structure is simple to manufacture, but the rotation angle detection precision is insufficient

Engineering Contradiction:

Improverotation angle detection precisionVSAvoidease of forming protrusions and recesses

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent applies curvature by forming convex and concave portions with curved surfaces instead of rectangular shapes on the rotor. This curvature enables the magnetic detection elements to detect smooth, periodic changes in magnetic field intensity, generating sine wave signals that significantly improve rotation angle detection precision while remaining manufacturable through conventional machining processes.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Measurement precision

If multiple magnetic detection elements are used to improve detection accuracy, then the measurement precision improves, but the device complexity increases

Engineering Contradiction:

Improvedetection accuracyVSAvoidnumber of magnetic detection elements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the detection function into multiple magnetic detection elements arranged around the rotor, with each element detecting magnetic field changes at different angular positions. This segmentation allows the system to capture complete rotational information through periodic sine wave signals, improving detection accuracy while maintaining manageable system complexity through modular arrangement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent utilizes periodic action by arranging magnetic detection elements to detect periodic changes in magnetic field intensity as the rotor rotates. The convex and concave portions are designed to generate periodic sine wave signals, allowing the system to determine rotation angle by analyzing the phase and amplitude of these periodic signals, thereby improving precision without proportionally increasing complexity.

Inventive Principle:

Principle #19Periodic action

3Measurement precision

If convex and concave portions change in a curved manner smoothly, then the magnetic field change detection precision improves, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvemagnetic field change detection precisionVSAvoidprecision of curved convex and concave portions

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent employs curved convex and concave portions that generate smooth magnetic field transitions, producing sine wave signals for precise rotation detection. The curved geometry, while requiring careful manufacturing, can be achieved through standard machining techniques and provides robust detection precision that tolerates reasonable manufacturing variations.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 highly accurate rotation angle detection by utilizing multiple magnetic detection elements to sense changes in the bias magnetic field caused by curved, periodic convex and concave portions on the rotor, enhancing detection precision and robustness.

Implementation Method 1

one bias magnetic field generation portion and a plurality of magnetic detection elements... the one bias magnetic field generation portion extends in the circumferential direction for one cycle of the convex and concave portions

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

a plurality of magnetic detection elements arranged along a circumferential direction of the stator... to detect a change in magnetic field intensity caused in association with a bias magnetic field

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentUS11408721B2Rotation angle detection device and rotation angle detection method

Publication Date: 2022.08.09 MITSUBISHI ELECTRIC MOBILITY CORP

AI summary

A rotation angle detection device, including: a rotor; a stator including one bias magnetic field generation portion (BMFGP) and magnetic detection elements; and a rotation angle calculation processor calculating a rotation angle of the rotor from detection signals of the detection elements, wherein a surface of the rotor has convex and concave portions (CCPs), which change in “x” (“x”≥1) cycles for a mechanical angle of 360, and a shape of the CCPs make the detection elements possible to obtain a sine wave, and wherein “a” (“a”≥2) detection elements are arranged along a circumferential direction of the stator at equal intervals for one cycle of the CCPs—so as to be opposed to the surface of the rotor, and the BMFGP extends in the circumferential direction for one cycle of the CCPs so as to overlap with the “a” detection elements.