Steering Motor Case Mounting for Vibration Isolation and Rigidity
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Solution Overview
Problem
Existing electric power steering systems face issues with reduced support rigidity of the motor case and stator relative to the housing, leading to increased inclination of the output shaft under G-forces during vehicle travel, and vibrations are not effectively suppressed from being conveyed to the attachment-receiving object.
Innovation Solution
A motor attaching structure that uses a fastening member to secure the motor case to an attachment-receiving object, featuring a cylindrical portion with a protruding bottom portion and internal fastening portions to enhance rigidity while suppressing vibration conveyance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the motor case is attached to the housing using a plate structure with press-fitted fittings, then vibrations generated by the motor are suppressed from being conveyed to the housing, but supporting rigidity of the case main body and stator relative to the housing becomes low
Solution Approach 1:
The motor case is divided into a case main body and a separate plate structure. The plate is press-fitted to the case main body and extends radially outward to provide attachment points for fastening bolts, while the case main body itself maintains structural integrity to support the stator and rotor assembly
Solution Approach 2:
The plate acts as an intermediary element between the case main body and the housing. It provides a mounting surface for fastening members that connect the motor assembly to the housing, while the case main body with its bottom portion provides vibration isolation through controlled clearances
2Object-affected harmful factors
If the motor case is attached to the housing using a plate structure with press-fitted fittings, then vibrations are suppressed, but the output shaft becomes inclined more readily due to G-forces during vehicle travel
Solution Approach 1:
The motor case structure is segmented into the case main body and plate portion, allowing each to perform its specialized function: the case main body houses and positions the stator and rotor with precise tolerances to maintain output shaft alignment, while the plate handles mounting and vibration isolation
Solution Approach 2:
Different portions of the motor case have different structural properties optimized for their specific functions. The case main body has high rigidity and precision where it houses the motor components to maintain alignment, while the plate provides flexibility for vibration isolation and mounting
Data Source
AI summary
A motor attaching structure, a motor unit, and a vehicle steering device, capable of suppressing vibrations generated by a motor from being conveyed to an attachment-receiving object, while maintaining support rigidity regarding the motor by attaching a motor case to an attachment-receiving object by a fastening member. A motor case of a motor, in which a stator and a rotor are housed in the motor case, is attached by bolts to a housing serving as an attachment-receiving object. The motor case has a cylindrical portion that houses the stator, and a bottom portion that is provided so as to protrude toward an inner side in a radial direction from one end portion of the cylindrical portion. A fastening portion for receiving the bolt is provided on the bottom portion on an inner side of an outer peripheral face of the cylindrical portion.