In-Wheel Motor Brake Disk Structure for Reduced Axial Space
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Solution Overview
Problem
In-wheel motors protrude from the wheel's inner space area, leading to increased cabin space requirements and potential interference with suspension systems due to their size and positioning relative to brake disks.
Innovation Solution
The in-wheel motor drive device incorporates a wheel hub bearing unit with a stationary outer ring and inner ring, where the fixing bolt for the outer ring is positioned within the cylindrical portion of the brake disk, allowing for reduced axial dimensions by eliminating clearance between the brake disk and the bolt, thus minimizing the overall size of the in-wheel motor drive device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the in-wheel motor is made small to fit within the inner space area of the wheel, then the wheel house size and cabin space are preserved, but the motor cannot accommodate the necessary components including the brake disk and fixing means
Solution Approach 1:
The fixing bolt is repositioned from a conventional location to extend axially through the brake disk, utilizing the axial dimension rather than radial or lateral space. This allows the fixing means to be integrated within the existing brake disk structure without increasing the overall footprint in the wheel's inner space area.
Solution Approach 2:
The fixing bolt is nested within the brake disk structure, with the bolt extending through the brake disk's axial direction. This nesting approach allows multiple components (brake disk, fixing bolt, motor) to occupy overlapping spatial volumes, maximizing space utilization within the wheel's inner space area.
2Adaptability or versatility
If the in-wheel motor protrudes from the inner space area of the wheel, then the motor can accommodate necessary components, but the wheel house needs to be enlarged sacrificing cabin space
Solution Approach 1:
The motor and brake disk are configured to overlap in the axial direction rather than extending radially outward. This dimensional reorganization allows all components to fit within the existing wheel house boundaries without sacrificing cabin space.
3Adaptability or versatility
If the in-wheel motor protrudes from the inner space area of the wheel, then the motor can accommodate necessary components, but the protruding portion interferes with the suspension device
Solution Approach 1:
By reorganizing components to overlap axially rather than extending radially, the motor assembly clears the suspension device's operational space, eliminating interference while maintaining component functionality.
4Reliability
If clearance is provided between the brake disk and fixing bolt in the axial direction, then the fixing means can properly secure the outer ring, but the dimension in the axial direction increases
Solution Approach 1:
The fixing bolt is nested within the brake disk's axial space, with the bolt extending through the brake disk thickness. This nesting eliminates the need for additional clearance beyond the brake disk's own thickness, minimizing the overall axial dimension while maintaining secure fixing.
Solution Approach 2:
The fixing means utilizes the brake disk's existing axial thickness rather than requiring additional axial clearance, repositioning the fixing function within the available dimensional envelope of the brake disk structure.
Data Source
AI summary
An in-wheel motor drive device (10) includes a wheel hub bearing unit (11) having an outer ring (13), an inner ring (12) protruding from the outer ring to one side in an axial (O) direction, rolling elements (14) between the outer ring and the inner ring, and a fixing bolt (15) for fixing the outer ring to a non-rotary member (102); and a brake disk (55) having a connecting portion (58) configured to connect with one end of the inner ring, a cylindrical portion (57) extending from the connecting portion to the other side in the axial direction and disposed coaxially to the inner ring, and at least a part of the fixing bolt is received in an internal space of the cylindrical portion.