Vehicle Drive Device Case Segmentation for Compact Packaging
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Solution Overview
Problem
Existing vehicle drive devices require multiple parts and bosses to join the case components, leading to increased size and production costs due to the need for numerous seal members to prevent oil leakage.
Innovation Solution
A vehicle drive device configuration with a separate support member inside the case, allowing the rotary electric machine, input, counter gear mechanism, and differential gear device to be positioned on distinct axes, minimizing the number of case parts and bosses, and reducing the number of seal members needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the peripheral wall portion of the case is divided into a plurality of parts in the axial direction, then the case can accommodate the rotary electric machine, input, counter gear mechanism, and differential gear device, but the number of bosses and seal members increases, resulting in increased case size and production costs
Solution Approach 1:
The case is divided into a first case portion and a second case portion that are joined together. The first peripheral wall includes a first joining portion, and the second peripheral wall includes a second joining portion, creating a segmented structure that accommodates different components (rotary electric machine in the first portion, counter gear mechanism and differential gear device in the second portion) while maintaining a manageable number of joining interfaces
Solution Approach 2:
The peripheral walls are extended in the axial direction to include joining portions that protrude radially outward. This dimensional extension allows the case portions to be joined together while providing boss structures for secure connection, effectively using the axial dimension to solve the accommodation problem without excessively increasing radial size
2Adaptability or versatility
If the peripheral wall portion of the case is divided into a plurality of parts in the axial direction, then the case can accommodate the rotary electric machine, input, counter gear mechanism, and differential gear device, but the number of seal members increases, resulting in increased production costs
Solution Approach 1:
The case is segmented into two main portions joined by a limited number of joining portions, which reduces the total number of seal members needed compared to dividing the case into more parts. This segmentation provides just enough division to accommodate different components while minimizing the number of sealing interfaces required
Solution Approach 2:
The joining portions serve multiple functions: they structurally connect the first and second case portions together, provide boss structures for mechanical joining, and incorporate seal members to prevent oil leakage. This multi-functionality reduces the need for separate components and minimizes the total number of seal members required
3Adaptability or versatility
If the number of parts into which the peripheral wall portion is divided increases, then the case can accommodate more components, but the size of the case increases
Solution Approach 1:
The case is divided into exactly two portions (first and second case portions) rather than more, which provides sufficient accommodation for all components (rotary electric machine, input, counter gear mechanism, differential gear device) while minimizing the total case volume. This optimal segmentation avoids the volume increase that would result from further division into more parts
Data Source
AI summary
A vehicle drive device including: a rotary electric machine that serves as a drive power source for a plurality of wheels; an input drivingly coupled to the rotary electric machine; a counter gear mechanism; a differential gear device that distributes a driving force transmitted from the rotary electric machine via the input and the counter gear mechanism, to the plurality of wheels; a case that accommodates the rotary electric machine, the input, the counter gear mechanism, and the differential gear device; and a support that is a separate member from the case, and is fixed inside the case.