Vehicle Drive Ring Gear Centering via Intermediate Wall
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Solution Overview
Problem
Existing vehicle drive apparatuses face challenges in achieving accurate axis alignment of the ring gear, leading to poor tooth contact and increased gear noise due to the complexity of machining the inner surface of the case and the use of intermediate members, which compromise gear durability and noise reduction.
Innovation Solution
A vehicle drive apparatus where the ring gear is fixed to an intermediate wall via a ring gear flange, utilizing a centering mechanism and a locking mechanism to ensure accurate alignment and secure fixation, eliminating direct contact between the ring gear and the case, thus reducing vibration transmission and gear noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ring gear is fixed to the case on the outer periphery of the ring gear, then the gear noise emitted from the case can be reduced, but the axis accuracy of the ring gear is aggravated
Solution Approach 1:
The patent introduces an intermediate member (fixing member) positioned between the ring gear and the case. This intermediary component serves dual functions: it provides shock absorption to reduce gear noise transmitted to the case, while simultaneously enabling accurate centering of the ring gear through precisely machined fitting surfaces. The intermediate member acts as a mediator that decouples the conflicting requirements of noise reduction and positioning accuracy.
2Object-affected harmful factors
If the ring gear is fixed to the case on the outer periphery of the ring gear, then the gear noise emitted from the case can be reduced, but the machining cost and difficulty increase
Solution Approach 1:
The intermediate fixing member serves as a manufacturable intermediary that transfers the fixing function from the difficult-to-machine inner surface of the case to more accessible outer surfaces. This allows standard machining operations to be used instead of complex internal machining, significantly reducing manufacturing difficulty and cost while maintaining the noise reduction function.
Solution Approach 2:
The fixing function is segmented into multiple components: the ring gear, the intermediate fixing member, and the case. This segmentation allows each component to be manufactured independently with appropriate machining operations, avoiding the need for complex single-step machining of the case's inner surface.
3Manufacturing precision
If an intermediate member is interposed between the ring gear and the case, then the axis accuracy of the ring gear is improved, but the device complexity increases
Solution Approach 1:
The intermediate fixing member is designed to perform multiple functions simultaneously: it provides shock absorption for noise reduction, enables accurate centering of the ring gear, and serves as a structural connector between the ring gear and case. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
Data Source
AI summary
A vehicle drive apparatus includes a motor generator, a speed reduction mechanism connected to a rotor shaft of the motor generator, an output shaft connected to the speed reduction mechanism, an intermediate wall separating the motor generator from the speed reduction mechanism, and a bearing that is fixed to the intermediate wall and supports the rotor shaft. The motor generator, intermediate wall, speed reduction mechanism, and output shaft are disposed in this order, and a ring gear of the speed reduction mechanism is fixed. The ring gear is fixed to the intermediate wall via a ring gear flange that is positioned relative and fixed to the intermediate wall by a centering mechanism and a locking mechanism. The centering mechanism is formed by fitting a boss of the ring gear flange and the intermediate wall. The locking mechanism is disposed on an outer peripheral side relative to the centering mechanism.