Wheel Bearing Preload Inspection Using Axial Gap and Torque

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Solution Overview

Problem

Current preload inspection methods for vehicle wheel bearing devices lack the accuracy needed to meet the increasing demand for reduced fuel consumption and efficient operation, as they rely primarily on axial gap measurements which are not sufficient for precise preload verification.

Innovation Solution

A method involving press-fitting, rotational torque measurement, and caulking steps to calculate and verify preload values by determining the difference between initial and final axial gaps and corresponding rotational torques, ensuring the preload is within a predetermined threshold for optimal performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If only axial gap measurement is used for preload inspection, then the inspection process is simple, but the measurement precision is insufficient

Engineering Contradiction:
Improvepreload measurement precisionVSAvoidinspection process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple measurement methods (axial gap measurement and rotational torque measurement) into a unified preload inspection process. By merging these complementary measurement approaches, the system achieves higher measurement precision while maintaining practical inspectability through integrated measurement steps.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces rotational torque measurement as an intermediary parameter to indirectly assess preload conditions. This intermediary measurement provides additional information about the bearing's actual preload state, complementing the direct axial gap measurement and enabling more precise preload verification.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If preload is excessively applied to increase rigidity, then rigidity increases, but rotational torque increases and life decreases

Engineering Contradiction:
Improvebearing rigidityVSAvoidrotational torque
Core Design Contradiction:
StrengthVSForce

Solution Approach 1:

The patent implements a feedback mechanism by measuring both axial gap and rotational torque, then comparing these measurements against predetermined standards. This feedback loop enables verification of whether the applied preload achieves the desired rigidity without exceeding optimal limits that would cause excessive rotational torque and reduced bearing life.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent monitors changes in multiple parameters (axial gap and rotational torque) to assess thepreload state. By tracking how these parameters change together, the system can determine the optimal preload level that maximizes rigidity while minimizing negative effects on rotational torque and bearing life.

Inventive Principle:
Principle #35Parameter changes

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

This method provides higher accuracy in verifying preload values, ensuring appropriate preload application, which enhances the bearing device's performance, reduces rotational torque, and extends its life.

Implementation Method 1

a press-fitting step of press-fitting the inner ring into the small-diameter step portion to a position where the inner ring abuts on the hub ring in the axial direction

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

a first rotational torque measurement step of measuring a first rotational torque of the bearing device when the inner member and the outer member are relatively rotated

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

a caulking step of caulking an inner-side end portion of the small-diameter step portion to the inner ring

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP3936847B1Preload inspection method and assembly method for bearing device for vehicle wheel
Publication Date: 2023.11.08 NTN CORP
  • EP3936847B1 patent drawingFigure 1
  • EP3936847B1 patent drawingFigure 2
  • EP3936847B1 patent drawingFigure 3

AI summary

Provided is a preload inspection method for a wheel bearing device enabling more accurate checking of preload. The invention comprises: a press-fitting step S02 for press-fitting an inner ring 4 to a small-diameter stepped part 3a; a first bearing preload value calculation step S03 for calculating a first bearing preload value P1 on the basis of a first axial direction negative clearance G1; a first rotating torque measurement step S05 for measuring a first rotating torque Ta after the press-fitting step; a swaging step S06 for swaging the small-diameter stepped part to the inner ring after the first rotating torque measurement step; a second bearing preload value calculation step S07 for calculating a second bearing preload value P2 on the basis of a second axial direction negative clearance G2; a second rotating torque measurement step S08 for measuring a second rotating torque Tb after the swaging step; a third bearing preload value calculation step S09 for calculating a third bearing preload value P3 by adding, to the first bearing preload value, a preload change amount ΔP based on a differential torque ΔT between the first rotating torque and the second rotating torque; and a determination step S10 for determining the suitability of the preload from the second bearing preload value and the third bearing preload value.