Asymmetric Coding Element for Forklift Wheel Position Detection

Solution Overview

Problem

Existing methods for detecting the actual position of a steered wheel in electric steering systems for industrial trucks require large angular ranges during homing movements, making the process time-consuming and increasing tire wear.

Innovation Solution

A device and method that utilize a coding element with sections of differing arc lengths, where sections indicating straight-ahead travel have shorter arc lengths, allowing for efficient detection of the wheel's position by minimizing the homing movement, with a sensor detecting transitions between these sections to determine the actual position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the wheel is rotated through large angular ranges during homing movement to detect sections on the coding element, then the actual position can be determined, but the process becomes time-consuming and increases tire wear

Engineering Contradiction:

Improvedetection accuracyVSAvoidhoming time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The coding element is divided into multiple sections with different arc lengths, where each section represents a specific angular range. By segmenting the detection task into discrete sections, the system can quickly identify the current section and determine position without requiring full rotation through all possible sections, thus reducing homing time while maintaining detection accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the coding element have different arc lengths tailored to their specific functions. The section corresponding to straight-ahead travel has a shorter arc length, allowing the wheel to be identified in this critical position with minimal rotation. This local optimization of section lengths reduces the overall angular range required for homing while ensuring accurate position detection.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If the wheel is rotated through large angular ranges during homing movement, then the actual position can be determined, but tire wear increases

Engineering Contradiction:

Improvedetection accuracyVSAvoidtire wear

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The coding element is divided into multiple sections with different arc lengths, where each section represents a specific angular range. By segmenting the detection task into discrete sections, the system can quickly identify the current section and determine position without requiring full rotation through all possible sections, thus reducing homing time while maintaining detection accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the coding element have different arc lengths tailored to their specific functions. The section corresponding to straight-ahead travel has a shorter arc length, allowing the wheel to be identified in this critical position with minimal rotation. This local optimization of section lengths reduces the overall angular range required for homing while ensuring accurate position detection.

Inventive Principle:

Principle #3Local quality

3Device complexity

If sections with uniform arc lengths are used on the coding element, then the structure is simple, but the homing movement requires large angular ranges

Engineering Contradiction:

Improvecoding element structureVSAvoidhoming time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

Different sections of the coding element have different arc lengths tailored to their specific functions. The section corresponding to straight-ahead travel has a shorter arc length, allowing the wheel to be identified in this critical position with minimal rotation. This local optimization of section lengths reduces the overall angular range required for homing while ensuring accurate position detection.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The coding element employs asymmetric section lengths instead of uniform arcs. By making the straight-ahead section shorter than other sections, the system creates an asymmetric pattern that enables rapid identification of the neutral position. This asymmetric design reduces homing time while maintaining structural simplicity.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentEP3162668B1Device and method for capturing the current position of an electrically steered wheel

Publication Date: 2018.03.14 JUNGHEINRICH AG

Figure 1~2

AI summary

Device for detecting the actual position of a steered wheel in an electric steering system for a forklift truck, comprising: - a steering drive that positions the steered wheel, and - a detection device comprising a coding element with a plurality of sections of different arc lengths and a sensor moving relative thereto, - wherein the coding element has two types of sections, of which sections of the first type have an arc length that uniquely identifies the section, and - the steered wheel and the coding element are arranged relative to each other such that the section(s) of the first type have a shorter arc length for straight-ahead travel than the other sections of the first type.