Hub Unit Bearing Assembly Using Inner Ring Expansion for Preload Accuracy
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Solution Overview
Problem
The existing methods for controlling the preload in hub unit bearings for automobiles do not accurately account for the expansion of the inner ring during press fitting with the hub spindle, leading to inconsistencies in the preload applied to the rolling bodies, which can affect the bearing's performance and drivability.
Innovation Solution
A method that involves measuring the outer-diameter dimension of the inner ring before and after the swaging process to calculate the decrease in axial clearance, allowing for precise control of the preload by considering the expansion of the inner ring during both swaging and press fitting, ensuring the preload is within a specified range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the inner ring is externally fitted with the hub spindle by press fitting, then the inner ring expands and the rolling bodies are press fitted toward the axially outboard side, but the amount of expansion is not accurately controlled leading to preload variations
Solution Approach 1:
The patent applies preliminary action by measuring the outer-diameter dimension of the inner ring before the swaging process (pre-fitting state) and using this measurement to predict and control the preload that will be applied to the rolling bodies after assembly. This allows the preload to be controlled in advance based on the inner ring's expansion characteristics during press fitting.
Solution Approach 2:
The patent implements feedback by measuring the outer-diameter dimension of the inner ring, calculating the expected preload based on this measurement and the known relationship between expansion and preload, and then adjusting the swaging amount to achieve the target preload. This closed-loop control ensures accurate preload application despite variations in press fitting expansion.
2Strength
If the preload applied to the rolling bodies is too large, then the moment rigidity is improved, but the dynamic torque increases and bearing life is reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the preload parameter within an optimal range (50-150 N) based on measured outer-diameter dimensions of the inner ring. By adjusting the preload parameter according to the actual expansion of the inner ring during press fitting, the patent achieves optimal moment rigidity while preventing excessive dynamic torque that would reduce bearing life.
3Reliability
If the preload applied to the rolling bodies is too small, then the bearing life is extended, but the moment rigidity is insufficient and drivability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the preload parameter within an optimal range (50-150 N) based on measured outer-diameter dimensions of the inner ring. By adjusting the preload parameter according to the actual expansion of the inner ring during press fitting, the patent ensures sufficient moment rigidity for good drivability while avoiding excessive preload that would reduce bearing life.
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 approach enables more accurate control of the preload applied to the rolling bodies, improving the hub unit bearing's performance by maintaining optimal dynamic torque and moment rigidity, thus enhancing the vehicle's drivability and extending the bearing's lifespan.
Implementation Method 1
a swaged portion that is formed by plastically deforming a tubular portion (25) of the hub spindle
Implementation Method 2
when the inner ring expands (outer-diameter dimension of the inner ring increases) as the inner ring is externally fitted with the hub spindle by press fitting
Data Source
AI summary
An amount of decrease ΔC in an axial clearance of a hub unit bearing is found based on an amount of expansion ΔD of an inner ring of the hub unit bearing, which is the difference between the outer-diameter dimension D1 of the inner ring after the inner ring is externally fitted with a tubular fitting portion of a hub spindle of the hub unit bearing and after formation of a swaged portion of the hub spindle, the inner ring being held between the swaged portion and a stepped surface of the hub spindle, and an outer-diameter dimension D0 of the inner ring before the inner ring is externally fitted with the tubular fitting portion.