Angle Sensor Delta Wheel Backlash Elimination

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Solution Overview

Problem

Existing angle sensors with measuring pinions and a drive pinion face hysteresis issues due to backlash, leading to measurement errors and safety concerns, particularly when the measuring pinions are indirectly coupled, and previous solutions either increase hysteresis or introduce measurement errors.

Innovation Solution

A delta wheel with coaxially arranged toothed rims is inserted between the measuring pinions, pre-tensioned using a spring or friction clutch, to constantly press the teeth against the drive pinion, eliminating backlash and hysteresis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If measuring pinions are indirectly coupled to the drive pinion, then the structure is more flexible and easier to manufacture, but backlash occurs leading to hysteresis and measurement errors

Engineering Contradiction:
Improveease of manufactureVSAvoidmeasurement precision
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

A resilient bearing is introduced as an intermediary element between the measuring pinion and the drive pinion. This resilient bearing absorbs backlash while maintaining a reliable mechanical connection, thereby eliminating measurement errors without complicating the manufacturing process

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If resilient bearing is used to eliminate backlash, then hysteresis is reduced, but measurement error increases due to displacement of measuring pinion axis

Engineering Contradiction:
Improvefreedom from hysteresisVSAvoidmeasurement error
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The measurement function is segmented between two independent measuring pinions with different tooth counts. Both pinions engage with the same drive pinion teeth, and their relative positional differences are evaluated to determine the drive pinion's angular position, thereby compensating for any displacement errors

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If two measuring pinions with different tooth counts are used, then measurement range exceeds 360° with high precision, but the structure becomes more complex

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The drive pinion serves multiple functions: it is engaged by both measuring pinions simultaneously, and its teeth are used by both pinions for measurement. This multi-functional design allows the system to achieve multi-revolution measurement capability with high precision while keeping the overall structure relatively simple

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

The solution effectively reduces hysteresis and measurement errors by ensuring consistent tooth engagement, maintaining accuracy and safety across multiple revolutions without the risk of tooth skipping or jamming.

Implementation Method 1

The gear rims of the delta wheel are connected to one another using a viscous, friction or magnetic clutch or a tensionable spring

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 2

The gear rims of the delta wheel are connected to one another using a viscous, friction or magnetic clutch or a tensionable spring

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

The gear rims of the delta wheel are connected to one another using a viscous, friction or magnetic clutch or a tensionable spring

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Data Source

PatentEP2018518B1Angle sensor
Publication Date: 2009.10.14 LEOPOLD KOSTAL GMBH & CO KG
  • EP2018518B1 patent drawingFigure 1~2

AI summary

Disclosed is an angle sensor that has an angle measuring range exceeding one full rotation and is used especially for a motor vehicle. Said angle sensor comprises a drive pinion and two driven measuring pinions, the number of full rotations of the drive pinion being determined from the position of the two measuring pinions. A delta wheel encompassing two coaxially arranged gear rims is inserted between the measuring pinions. The two gear rims mesh with one respective measuring pinion while being movable towards each other only by applying force.