Electric Traction Wheel Hub With Nested Motor and Transmission
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Solution Overview
Problem
Existing electric axles in heavy-duty vehicles are bulky, necessitating modifications to suspension systems and compromising useful vehicle space due to the presence of electric machines, and there is a need for optimized and cost-effective integration of electric traction systems with rims.
Innovation Solution
A wheel hub with integrated electric traction system is designed, featuring a compact and lightweight axle with an electric machine and transmission housed within the wheel hub, along with a cooling and electrical power system integrated into the axle, allowing for a modular and scalable design that minimizes external exposure and simplifies assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric machines are integrated into wheel hubs, then vehicle pollutant emissions are reduced and regenerative braking is enabled, but overall dimensions increase and useful space is reduced
Solution Approach 1:
The electric machine is nested within the hollow central portion of the wheel hub, with the stator positioned in the hollow central portion and the rotor surrounding it. The transmission is nested within the hollow end portions of the axle. This nesting arrangement allows the electric machine and transmission to be integrated within the existing wheel hub structure without significantly increasing overall dimensions.
Solution Approach 2:
The patent utilizes the hollow central and end portions of the axle as three-dimensional spaces to house the electric machine and transmission components. By arranging components along the axial and radial dimensions of the hollow portions, the design accommodates the electric machine without increasing the outer diameter or overall length of the wheel hub assembly.
2Reliability
If electric machines are integrated into wheel hubs, then regenerative braking is enabled, but structural characteristics of rims are compromised
Solution Approach 1:
The wheel hub is segmented into distinct functional portions: the hollow central portion houses the electric machine, the hollow end portions house the transmission, and the solid portions maintain structural integrity. The rim is designed as a separate component that connects to these segmented portions, allowing each segment to be optimized for its specific function without compromising overall structural strength.
Solution Approach 2:
The electric machine, transmission, and rim are merged into a single integrated wheel hub assembly. The electric machine and transmission are positioned within the hollow portions of the axle, while the rim is connected to the solid portions, creating a unified structure that combines regenerative braking capability with rim structural strength.
3Volume of moving object
If compact design is used to reduce dimensions, then useful space is optimized, but manufacturing complexity increases
Solution Approach 1:
The hollow central and end portions of the axle serve multiple functions: they provide structural support for the wheel hub, contain the electric machine and transmission, and facilitate cooling fluid flow. This multi-functionality reduces the need for separate cooling systems and structural components, thereby simplifying manufacturing despite the compact design.
Solution Approach 2:
Instead of adding external cooling systems or structural reinforcements to achieve compact design, the patent inverts the approach by utilizing the existing hollow portions of the axle as the cooling and structural framework. The cooling fluid flows through the hollow portions, and the solid portions provide structural support, eliminating the need for additional complex manufacturing steps.
4Volume of moving object
If hollow portions are used to house electric machine and transmission, then overall dimensions are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The hollow portions of the axle are designed with specific local qualities: the hollow central portion has dimensions and tolerances optimized for housing the electric machine, while the hollow end portions have dimensions optimized for the transmission. This localized optimization allows each hollow portion to be manufactured with appropriate precision for its specific function, reducing overall manufacturing complexity.
Solution Approach 2:
The hollow portions of the axle are pre-formed during the axle manufacturing process, with the electric machine and transmission designed to fit into these pre-formed cavities. This preliminary creation of the hollow portions with appropriate tolerances simplifies subsequent assembly operations and reduces the need for post-manufacturing precision work.
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
The solution provides a compact, lightweight, and protected electric traction system that reduces manufacturing time and cost, maintains structural integrity, and supports various vehicle types without compromising performance.
Implementation Method 1
electric machines such as motors/generators configured to give torque to the wheel hubs
Implementation Method 2
a cooling system and electrical connections
Data Source
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AI summary
A wheel hub (10) for an axle (1) of a heavy vehicle, comprising a fixed portion (8) configured to be rigidly carried by one end (3, 4) of the axle (1) and a movable portion (9) configured to be carried in a rotationally free manner by the same and with respect to the fixed portion (8), the fixed portion (8) and the movable portion (9) delimiting with the end (3, 4) a space (14) isolated from the external environment, the wheel hub (10) comprising an electric machine (15) housed in the space (14) and comprising a stator (15') carried integral with the fixed portion (8) and a rotor (15") operatively connected to the movable portion (9), the wheel hub (10) comprising a transmission (16) housed in the space (14), radially inside of the rotor (15"), and connecting the rotor (15") to the movable portion (19) so as to vary the speed/torque between the rotor (15") and the movable portion (9).