Crankshaft Load Cell Structure for Accurate Radial Force Sensing

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Solution Overview

Problem

Current load cell designs for determining radial forces on crankshafts lack efficient measurement and support mechanisms, particularly in gear housings, leading to inaccurate force calculations and potential damage to strain sensors.

Innovation Solution

A load cell with a cylindrical receiving sleeve and fastening ring, featuring measuring areas with strain sensors and axial support areas, designed to absorb radial and axial forces, respectively, and connected via connection areas to ensure controlled deformation and precise force measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If strain sensors are attached to measuring areas to detect radial forces, then measurement precision is improved, but the strain sensors are vulnerable to damage from axial forces

Engineering Contradiction:
Improveradial force measurementVSAvoidstrain sensor durability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The load cell is segmented into distinct functional areas: measuring areas with measuring tabs for radial force detection, and axial support areas with support tabs for axial force bearing. This segmentation allows strain sensors to be placed only where radial forces occur, protecting them from axial force damage while maintaining measurement precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The axial support areas act as intermediaries that bear and redirect axial forces away from the measuring areas. The support tabs with strain sensors detect axial forces separately, preventing these forces from damaging the radial force measuring sensors while maintaining overall structural integrity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If the load cell structure is simplified for ease of manufacture, then manufacturing precision may be compromised, affecting measurement accuracy

Engineering Contradiction:
Improveload cell fabricationVSAvoiddimensional accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The load cell merges multiple functions into a single integrated structure: the receiving sleeve, measuring areas, axial support areas, and fastening ring are formed as one piece. This merging simplifies manufacturing compared to assembling multiple separate components while maintaining the precise geometric relationships needed for accurate force measurement.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The design uses parameter optimization in the tab geometries and slot dimensions to achieve both manufacturability and precision. The measuring tabs and support tabs are designed with specific dimensional parameters that allow standard manufacturing processes to produce the required precision without complex machining operations.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If measuring tabs are designed with large angular range to improve deformability, then the defined direction of radial force measurement is compromised

Engineering Contradiction:
Improvemeasuring tab deformabilityVSAvoidradial force direction definition
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The measuring tabs exhibit local quality differentiation: they have reduced thickness in specific regions to enhance deformability where needed, while maintaining adequate thickness and structural rigidity in other regions to preserve the defined direction of force measurement. This localized variation in geometric properties optimizes both deformability and measurement precision.

Inventive Principle:
Principle #3Local quality

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 design enables accurate measurement of radial forces, allowing for the calculation of torque on a crankshaft, while protecting strain sensors and providing stable support, thus enhancing the reliability and durability of force measurement systems.

Implementation Method 1

measuring areas which are intended to absorb radial forces of the receiving sleeve, which are transmitted from the ring of the bearing to the measuring areas. Strain sensors are attached to at least two of the measuring areas

Methodology Applied
Scientific EffectStrain: Deformation

Implementation Method 2

The load cell has axial support areas which are provided on the fastening ring for axially supporting the outer ring or ring of the bearing or for absorbing axial forces

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3978886B1Load cell for determining a radial force acting on a crankshaft
Publication Date: 2023.10.04 TQ SYST GMBH
  • EP3978886B1 patent drawingFigure 1
  • EP3978886B1 patent drawingFigure 2
  • EP3978886B1 patent drawingFigure 3

AI summary

A load cell for determining a radial force on a crankshaft, comprising a mounting sleeve for receiving a bearing ring and a mounting ring for securing the load cell in a gearbox housing. Axial support areas are provided on the mounting ring for axial support of the outer ring of the first bearing. Furthermore, measuring areas are provided for recording radial forces on the mounting sleeve, connecting the mounting sleeve to the mounting ring. Strain gauges are attached to at least two of the measuring areas.