EV Drive Unit Stator Support Layout for Compact Differential Assembly
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Solution Overview
Problem
Existing vehicle drive devices face challenges in minimizing the inter-axial distance between the rotary electric machine and the differential gear mechanism, which affects the size and weight of the case, due to potential interference and difficulties in centering and tilting of components during assembly.
Innovation Solution
The configuration includes an input member and differential gear mechanism with parts arranged on the axial first side with respect to the rotary electric machine, utilizing an outer peripheral support portion to center and hold the stator core, and notch portions to facilitate closer arrangement of components, reducing the inter-axial distance and thus the overall size and weight of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the differential gear mechanism is arranged close to the rotary electric machine to reduce inter-axial distance, then the case size is reduced, but component interference occurs making assembly difficult
Solution Approach 1:
The differential gear mechanism is divided into multiple components (differential case, side gears, pinion gears, etc.) that can be assembled separately and then integrated. The case is segmented with opening portions that allow component insertion from the radial direction, enabling assembly without disassembling the entire compact structure.
Solution Approach 2:
A bearing is introduced as an intermediary component between the differential case and the case body, facilitating smooth assembly and positioning. The bearing acts as a mediator that enables the differential case to be properly positioned and secured within the compact arrangement.
2Volume of stationary object
If the stator core is positioned closer to the shaft member to reduce radial dimension, then the inter-axial distance is shortened, but centering precision becomes difficult to maintain
Solution Approach 1:
The stator core is pre-positioned and fixed to the case body before assembling other components. The opening portions are designed to accommodate the stator core in a predetermined position, ensuring proper centering is established early in the assembly process and maintained throughout.
Solution Approach 2:
Complex mechanical centering mechanisms are replaced by the geometric design of the opening portions and the inherent alignment features of the stator core. The radial positioning is achieved through the structural arrangement rather than additional centering devices.
3Ease of manufacture
If the case structure is simplified to reduce manufacturing cost, then the number of divisions is reduced, but assembly precision and component positioning become compromised
Solution Approach 1:
The case body is designed with multi-functional features: the opening portions serve both as access paths for assembly and as positioning references for component alignment. The peripheral wall portion integrates multiple functions including structural support, component mounting surfaces, and alignment features, reducing the need for additional specialized components.
Data Source
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AI summary
An input member and a differential gear mechanism include a part arranged on an axial first side with respect to a rotary electric machine. The differential gear mechanism is connected to a first wheel via a shaft member (61) including a part that is arranged on an axial second side with respect to the differential gear mechanism. A case (2) includes an outer peripheral support portion (25) that is formed along a core outer peripheral surface (12a) that is an outer peripheral surface of a stator core (12), and that supports the core outer peripheral surface (12a) in a radial direction (R). A notch portion (26A) in which the outer peripheral support portion (25) is notched over an entire area of an arrangement area of the stator core (12) in an axial direction is formed in the outer peripheral support portion (25), and the notch portion (26A) is arranged at a position that is between the core outer peripheral surface (12a) and the shaft member (61) in the radial direction (R), and that overlaps the shaft member (61) as seen in the radial direction along the radial direction (R).