Vehicle Power Transmission Unit with Nested Shaft Brake Layout
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Solution Overview
Problem
The existing vehicle power transmission units have a lengthened fitting portion due to the axial division between the motor shaft and input shaft, which affects the mountability on vehicles.
Innovation Solution
The brake unit is positioned opposite to the electric travel motor in the housing, with a recess formed in the input shaft end to accommodate the motor shaft, reducing the overall length and improving mountability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coupling is used to connect the motor shaft and input shaft via spline engagement, then power transmission is achieved, but the length from the housing side end surface to the brake unit increases
Solution Approach 1:
The motor shaft end is inserted into a recess formed in the input shaft, creating a nested configuration where one component fits inside another. This eliminates the need for an external coupling and reduces the overall axial length while maintaining power transmission capability through the spline engagement between the motor shaft outer peripheral surface and the recess inner peripheral surface.
2Reliability
If the fitting portion is divided into two via coupling, then power transmission is achieved, but the overall length increases affecting mountability
Solution Approach 1:
The motor shaft and input shaft are directly connected by forming a recess in the input shaft that receives the motor shaft end, merging what were previously separate coupling components into an integrated shaft connection. This reduces the number of separate parts and simplifies the assembly structure, improving mountability while maintaining reliable power transmission.
Data Source
AI summary
[Problem] Mountability of the vehicle power transmission unit, in which the brake unit is disposed on the side opposite to the electric travel motor in the housing, on the vehicle is improved.[Solution] A power transmission unit 41 includes an electric travel motor 30, an input shaft, a gear mechanism 80a, and a housing 44. Power from the motor is transmitted to the input shaft, gear mechanism, and axle in sequence. A brake unit 90 is mounted on the housing opposite the motor and connected to the second end of the input shaft 60. A recess 60d is formed at the first end of the input shaft, into which the motor shaft 32 is inserted, with a power transmission part 33, 62 interposed between the recess and the motor shaft end.