Rolling Element Cage Structure for Higher Power Density
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Solution Overview
Problem
Traditional rolling element cages in displacement units for vehicles have limited power density due to the spacing required for manufacturing, which restricts the packing density of rolling elements and affects the efficiency of longitudinal compensation in vehicle powertrains.
Innovation Solution
A rolling element cage design with guide structures positioned laterally along the outer surface and support structures on the inner surface, allowing for closer spacing of openings and rolling elements, enabling direct contact and increased packing density without limiting axial movement, and featuring end areas with ramps and plateaus to manage axial forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional rolling element cage design is used with sufficient spacing for manufacturing, then manufacturing ease is improved, but power density deteriorates due to limited packing density of rolling elements
Solution Approach 1:
The cage is divided into multiple segments or sections, each containing rolling elements. This segmentation allows for modular manufacturing with sufficient spacing between sections, while each section can be densely packed with rolling elements, thereby resolving the contradiction between manufacturing ease and power density.
Solution Approach 2:
The invention transitions from a traditional single-plane arrangement of rolling elements to a multi-dimensional configuration where rolling elements are arranged in multiple rows and columns within the cage structure. This dimensional expansion increases the packing density of rolling elements without compromising manufacturing feasibility, thus improving power density while maintaining ease of manufacture.
2Quantity of substance
If rolling elements are packed densely to increase power density, then power density is improved, but manufacturing precision deteriorates due to tighter tolerances required
Solution Approach 1:
By segmenting the cage into multiple sections with rolling elements arranged in a grid pattern across multiple planes, the design achieves high power density through increased rolling element count while each individual section maintains manageable manufacturing tolerances, thus resolving the precision-density trade-off.
Solution Approach 2:
The invention changes the geometric parameters of the cage structure, including the arrangement pattern and spacing of rolling elements, to optimize the balance between packing density and manufacturability. Specific parameter optimizations in the multi-dimensional arrangement allow dense packing without excessive tolerance requirements.
3Quantity of substance
If more rolling elements are accommodated in the same space to enhance power density, then power density is improved, but device complexity increases due to tighter spacing of openings and guide structures
Solution Approach 1:
The cage is segmented into multiple sections with standardized opening and guide structure patterns in each section. This modular segmentation allows for increased rolling element capacity through repetition of proven design units, thereby enhancing power density while avoiding exponential increases in overall device complexity.
Solution Approach 2:
The guide structures and openings are designed with universal characteristics that serve multiple functions: guiding rolling elements, maintaining spacing, and facilitating assembly. This multi-functionality reduces the number of specialized components needed, allowing more rolling elements to be accommodated without proportionally increasing device complexity.
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 enhances power density by allowing more rolling elements in the same space, reduces manufacturing costs, and effectively transmits axial forces directly between rolling elements, preventing damage from high axial forces during assembly and operation.
Implementation Method 1
The plurality of rolling elements are configured to be received at least partially within (i) the plurality of external raceways of the pin and (ii) the plurality of internal raceways of the sleeve
Data Source
AI summary
A displacement unit includes a pin, a sleeve, a plurality of rolling elements, and a rolling element cage. The pin includes a plurality of external raceways. The sleeve includes a plurality of internal raceways. The sleeve is configured to receive at least a portion of the pin. The rolling element cage includes a plurality of openings configured to each accommodate a rolling element of the plurality of rolling elements. The rolling element cage is configured to be received around the pin and disposed radially between the pin and the sleeve. The plurality of rolling elements are configured to be received at least partially within (i) the plurality of external raceways of the pin and (ii) the plurality of internal raceways of the sleeve.