In-Wheel Motor Bolt Layout for Case Sealing and Oil Leak Control
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Solution Overview
Problem
Existing in-wheel motor drive devices face challenges in maintaining effective sealing between the motor case and reduction gear case due to large bolt fastening intervals, leading to deformation and difficulty in suppressing oil leakage.
Innovation Solution
The device employs a configuration where a pair of fastening bolts facing each other across the stator coil end portion are arranged on the same radial line, with the center lines of these bolts normal to the motor's axis, minimizing the bolt joint distance and reducing deformation, and uses a sealing material applied to the mating surfaces to enhance sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the bolt fastening interval is large, then the device complexity is reduced, but the sealing property deteriorates due to case deformation
Solution Approach 1:
The patent applies different bolt arrangement strategies to different regions: inside the stator coil end portion and outside the stator coil end portion. This local differentiation optimizes sealing at critical interfaces while maintaining overall structural simplicity
Solution Approach 2:
The bolt configuration is asymmetric relative to the motor axis, with specific bolts positioned at predetermined angles in radial cross-section. This asymmetric arrangement targets deformation-prone areas more effectively than symmetric patterns
2Reliability
If the bolt joint distance is minimized, then the sealing property is improved by reducing deformation, but the manufacturing precision requirements increase
Solution Approach 1:
The patent pre-determines bolt positions at specific angles in radial cross-section before assembly. This preliminary positioning planning ensures optimal joint distance while accounting for manufacturing tolerances, reducing the actual precision burden during assembly
3Reliability
If fastening bolts are arranged to face each other across the stator coil end portion on the same radial line, then the sealing property is improved, but the device complexity increases
Solution Approach 1:
The fastening system is segmented into distinct functional groups: bolts inside the stator coil end portion and bolts outside it. Each segment serves specific sealing requirements, allowing independent optimization without complicating the entire fastening system
Data Source
AI summary
An in-wheel motor drive device includes: a motor case housing a motor provided in a wheel of a drive wheel; a reduction gear case housing a reduction gear; and a plurality of fastening bolts for fastening the motor case and the reduction gear case. Further, among the plurality of fastening bolts, a pair of fastening bolts facing each other across a stator coil end portion of the motor is arranged on a same straight line in a radial direction orthogonal to an axis direction of the motor.