Twin Gear Transmission Layout for Vehicle NV and Cost Control
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Solution Overview
Problem
Existing vehicle drive apparatuses with symmetrically arranged left-side and right-side gear transmission mechanisms require different gears, increasing manufacturing costs and complicating noise and vibration (NV) reduction due to independent shaping of tooth faces, leading to difficulty in achieving optimal NV performance.
Innovation Solution
The drive apparatus features independently combined left-side and right-side drive sources and gear transmission mechanisms with identical gear configurations, including parallel rotary shafts, shared casing, and symmetrical drive sources, allowing for identical gear positioning and reduced axial distances to minimize manufacturing costs and improve NV performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If left-side and right-side gear transmission mechanisms are arranged symmetrically in the width direction of the vehicle, then the drive apparatus achieves balanced power transmission, but corresponding gears must be constituted by different gears requiring independent tooth face shaping operations such as crowning and bias, thereby increasing manufacturing cost
Solution Approach 1:
The patent applies asymmetry by making the left-side and right-side gear transmission mechanisms asymmetric in arrangement. Specifically, the left-side gear transmission mechanism is arranged on the left side of the vehicle width direction while the right-side gear transmission mechanism is arranged on the right side, but they are positioned at different distances from the vehicle centerline. This asymmetric arrangement allows corresponding gears to be identical, eliminating the need for independent tooth face shaping operations and reducing manufacturing costs while maintaining balanced power transmission.
2Object-affected harmful factors
If corresponding gears of left-side and right-side gear transmission mechanisms are constituted by different gears, then each gear can be independently shaped to suppress NV, but it becomes difficult to reduce NV in the vehicle as a whole since the mechanisms have different NV characteristics
Solution Approach 1:
The patent applies homogeneity by making the left-side and right-side gear transmission mechanisms homogeneous in terms of gear configuration and NV characteristics. Corresponding gears are constituted by identical gears with the same tooth profiles and dimensions, ensuring that both mechanisms have the same NV characteristics. This allows for consistent NV performance across the entire drive apparatus while simplifying the noise and vibration control strategy.
3Object-affected harmful factors
If independent tooth face shaping operations such as crowning and bias are performed on corresponding gears, then NV is suppressed at the gear level, but the manufacturing cost including design cost increases
Solution Approach 1:
The patent extracts the need for independent tooth face shaping operations by making corresponding gears identical. Since the left-side and right-side gear transmission mechanisms are arranged asymmetrically, the same gear can be used on both sides without requiring separate crowning and bias operations for each side. This extraction of the independent shaping requirement significantly reduces manufacturing and design costs while still achieving NV suppression through the standardized gear design.
Data Source
AI summary
A drive apparatus is for a vehicle that includes left and right wheels. The drive apparatus includes: (a) a left-side gear transmission mechanism disposed between a left-side drive source and the left wheel; and (b) a right-side gear transmission mechanism disposed between a right-side drive source and the right wheel. Each of the left-side and right-side gear transmission mechanisms includes a plurality of rotary shafts and a plurality of gears. The left-side and right-side gear transmission mechanisms are the same as each other in terms of a number of the rotary shafts, a number of the gears and a positional relationship between the gears. Each of the gears of the left-side gear transmission mechanism and a corresponding one of the gears of the right-side gear transmission mechanism are identical with each other and disposed in the same attitude as each other.