Rotational Angle Detector Using Dual Detection Gears

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Solution Overview

Problem

Existing rotational angle detectors for rotors, such as steering wheels, can only immediately obtain new angles within a limited range (0 to 60 degrees) after ignition is turned ON, requiring 'dark current' to maintain power when the ignition is OFF, which is inefficient.

Innovation Solution

A rotational angle detector system using a main gear and two detection gears with different numbers of teeth, where the rotational angles of the detection gears are calculated using specific equations to determine the rotor's angle over a wide range without needing dark current, by employing a microcomputer to process signals from magneto-resistance elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single detection gear with a magnet is used to detect rotational angle, then the device structure is simple, but the detectable rotational angle range is limited to 0-60 degrees

Engineering Contradiction:

Improvedetection system structureVSAvoidrotational angle detection range

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The single detection gear is divided into two detection gears with different numbers of teeth (first detection gear with m teeth, second detection gear with L teeth where L>m). Each detection gear detects rotational angles within different ranges, and their combined output enables detection over a wide range (0-1620 degrees) without requiring dark current.

Inventive Principle:

Principle #1Segmentation

2Reliability

If power is supplied to the magneto-resistance element and microcomputer when ignition is OFF, then the rotational angle can be immediately obtained after ignition is turned ON, but dark current becomes necessary

Engineering Contradiction:

Improveimmediate angle detection capabilityVSAvoiddark current consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system performs preliminary detection actions during the limited 0-60 degree range when ignition is OFF, storing this initial angle information. When ignition is turned ON, the microcomputer uses this pre-acquired information combined with the two detection gears to immediately calculate the full rotational angle, eliminating the need for continuous dark current supply.

Inventive Principle:

Principle #10Preliminary action

3Loss of energy

If the ignition switch is turned OFF, then power consumption is reduced, but the microcomputer cannot obtain the new rotational angle immediately when ignition is turned ON

Engineering Contradiction:

Improvepower consumption when ignition is OFFVSAvoidtime delay in angle detection after ignition ON

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

4Adaptability or versatility

If two detection gears with different numbers of teeth are used, then the rotational angle detection range is extended to 0-1620 degrees, but the device complexity increases

Engineering Contradiction:

Improverotational angle detection rangeVSAvoiddetection gear structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The outputs from two detection gears with different tooth counts are merged through a mathematical relationship in the microcomputer. The first detection gear provides angle information for one cycle, the second provides angle information for another cycle, and their combination enables wide-range detection without requiring a single complex detection mechanism.

Inventive Principle:

Principle #5Merging (Combining)

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 immediate detection of rotational angles over a wide range (0 to 1620 degrees) without dark current, improving precision and eliminating the need for continuous power when the ignition is OFF.

Implementation Method 1

a magneto-resistance element for magnetically detecting the rotational angle of the detection gear

Methodology Applied

Scientific EffectMagneto-resistance: Magnetoresistance

Data Source

PatentUS7366636B2Rotational angle detector

Publication Date: 2008.04.29 KK TOKAI RIKA DENKI SEISAKUSHO

AI summary

A rotational angle detector for detecting the rotational angle of the rotor in a wide range without requiring dark current. A first detection gear including an m number of teeth and a second detection gear including an L number of teeth are each engaged with a main gear rotated integrally with a steering shaft which includes an n number of teeth. A microcomputer calculates a rotational angle θ of the steering shaft using a rotational angle α of the first detection gear within one cycle and a rotational angle β of the second detection gear within one cycle.