Angular Contact Bearing Assembly for Low-Loss EV Drive Trains
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Solution Overview
Problem
Existing rolling bearings in electric drive trains of motor vehicles face challenges in balancing low friction, high load rating, and acoustic unobtrusiveness, with standard solutions either being inefficient in load transmission or increasing noise and power loss.
Innovation Solution
A rolling bearing assembly using two axially spaced angular contact roller bearings, where one is fixed and the other is slightly floating, with minimal preload, allowing for high load capacity and low friction through line contact and optimized lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If standard rolling bearings are used in electric drive trains, then the structure is simple and easy to manufacture, but the load transmission efficiency is insufficient and power losses increase
Solution Approach 1:
The bearing assembly is divided into two separate angular contact roller bearings arranged axially spaced apart, with one fixed bearing and one floating bearing. This segmentation allows each bearing to be optimized for specific functions: the fixed bearing handles primary load transmission while the floating bearing accommodates thermal expansion and misalignment, reducing overall friction and power loss
Solution Approach 2:
The patent transitions from radial load support to axial load support by using angular contact roller bearings with cylindrical rolling bodies arranged at a contact angle. This dimensional change enables line contact between rolling bodies and race tracks, significantly increasing load capacity while maintaining low friction through optimized rolling motion
2Stability of the object's composition
If floating bearings with tight fit are used, then the bearing can accommodate thermal expansion, but friction increases and acoustic noise occurs
Solution Approach 1:
The bearing assembly separates the thermal expansion compensation function to the floating bearing only, while the fixed bearing maintains a tighter fit for stable load transmission. This segmentation allows the floating bearing to absorb thermal expansion and misalignment without generating noise, while the fixed bearing operates in a stable, low-noise condition
Solution Approach 2:
Different fit conditions are applied locally to different bearings: the fixed bearing has a tighter fit for stable load transmission, while the floating bearing has a looser fit to accommodate thermal expansion. This local differentiation optimizes both thermal compensation and noise reduction without compromising overall system performance
3Object-generated harmful factors
If bearings are prestressed to improve running conditions, then acoustics improve, but friction losses increase
Solution Approach 1:
The bearing assembly divides the prestressing function: the fixed bearing receives minimal preload for acoustic optimization, while the floating bearing operates with no preload to minimize friction. This segmentation allows acoustic abnormalities to be controlled without significantly increasing overall friction power loss
Solution Approach 2:
Instead of prestressing both bearings, the patent applies partial prestressing only to the fixed bearing at minimal levels. This partial action is sufficient to eliminate acoustic abnormalities while keeping friction power losses minimal, as the floating bearing compensates for any remaining play
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 provides a compact, low-friction, and acoustically unobtrusive design capable of handling high loads, reducing mechanical power losses, and enhancing the efficiency of electric drive trains.
Implementation Method 1
cylindrical rolling bodies arranged at a first contact angle are accommodated and roll on an inner race track of the first inner race and an outer race track of the first outer race
Data Source
AI summary
A rolling bearing assembly for an electrically operable drive train includes axially spaced first and second angular contact roller bearings, a shaft, rotatably mounted by the bearings, and first and second connecting structures. The first bearing has a first inner race with an inner race track, a first outer race with an outer race track, and rolling bodies arranged to roll on the race tracks at a first contact angle. The second bearing has a second inner race with an inner race track, a second outer race with an outer race track, and rolling bodies arranged to roll on the race tracks at a second contact angle. The first and second inner races are axially and rotationally fixed to the shaft, the first outer race is axially fixed relative to the first connecting structure, and the second outer race is axially displaceable relative to the second connecting structure.