Three-Intermediate-Shaft EV Drive Assembly for Low-NVH Torque Transfer
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Solution Overview
Problem
Existing electric vehicle gearbox designs face challenges with noise, vibration, and harshness (NVH) issues, particularly in planetary gearset coaxial structures, and require complex and costly manufacturing processes, as well as a larger center distance for torque transmission in offset coaxial structures.
Innovation Solution
A transmission gearbox with a gearbox input shaft and three evenly distributed intermediate shafts, forming a two-stage three-intermediate-shaft coaxial gear set, which eliminates the need for a ring gear, reduces center distance, and shares torque among the intermediate shafts, enhancing NVH performance and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a planetary gearset coaxial structure is used, then the center distance is reduced, but the NVH performance deteriorates and manufacturing complexity increases
Solution Approach 1:
The planetary gearset is segmented into multiple independent single-stage reduction mechanisms (first, second, and third single-stage reduction mechanisms) that work in parallel. Each mechanism processes a portion of the torque independently, which reduces the complexity and NVH issues associated with traditional planetary gearsets while maintaining the compact coaxial structure and small center distance.
2Length of stationary object
If a planetary gearset coaxial structure is used, then the center distance is reduced, but the manufacturing complexity and cost increase
Solution Approach 1:
The transmission system is divided into multiple independent single-stage reduction mechanisms, each with simpler gear structures that are easier to manufacture. This segmentation avoids the complex ring gears and precise meshing requirements of traditional planetary gearsets, reducing manufacturing complexity and cost while maintaining the compact coaxial design.
Solution Approach 2:
The invention uses standard, easily manufacturable gear components in each single-stage reduction mechanism rather than expensive, custom-designed planetary gear components. This approach prioritizes manufacturing simplicity and cost-effectiveness while achieving the same functional outcome of compact torque transmission.
3Force
If an offset coaxial structure is used, then the torque transmission capability is improved, but the center distance increases
Solution Approach 1:
Multiple single-stage reduction mechanisms are merged into a single coaxial transmission system, combining their torque transmission capabilities. This allows the system to achieve high torque transmission capability similar to offset coaxial structures while maintaining a compact center distance through the coaxial arrangement of all reduction mechanisms.
Solution Approach 2:
The torque transmission function is segmented across multiple independent single-stage reduction mechanisms arranged coaxially. Each mechanism contributes to the overall torque transmission capability, enabling the system to match or exceed the torque capacity of offset coaxial structures without requiring a larger center distance.
4Force
If traditional gearbox structures are used, then the torque transmission is achieved, but the number of meshed gears increases
Solution Approach 1:
The transmission system is segmented into multiple independent single-stage reduction mechanisms, each handling a portion of the total torque. This segmentation reduces the number of gears that need to mesh simultaneously compared to traditional multi-stage planetary gearsets, while still achieving the required overall torque transmission capability through the parallel arrangement of mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design improves NVH performance, reduces the overall volume and weight, allows for a more compact vehicle layout, and lowers production costs by simplifying the structure and eliminating the need for high-precision components, while maintaining high output torque and efficiency.
Implementation Method 1
the three first-stage driven gears are respectively meshed with the first-stage driving gear
Implementation Method 2
the three second-stage driving gears are respectively meshed with the second-stage driven gear
Data Source
AI summary
The disclosure relates to the technical field of electric drive assemblies, and in particular provides an electric drive assembly for an electric vehicle, and an electric vehicle. The disclosure provides an electric drive assembly composed of an input shaft integrated with an electric motor rotor and a gearbox first-stage driving gear, three intermediate shafts each integrated with a gearbox first-stage driven gear and a second-stage driving gear, and a differential integrated with a second-stage driven gear. The three intermediate shafts are evenly disposed around the input shaft. The power of the electric motor is transmitted from the first-stage driving gear to the second-stage driven gear on the differential evenly through the three intermediate shafts. The structure has a small size, a light weight, and a large ability to transmit loads, thereby avoiding the problem of poor manufacturing precision of the planetary gear and the ring gear used in the traditional coaxial electric drive assembly structure, and providing a better NVH performance.