Electric Vehicle Drive Device Axial Length Reduction
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Solution Overview
Problem
Electric vehicle driving devices face challenges in reducing size in the axial direction while maintaining torque output, as existing designs limit the non-overlapping arrangement of motors and transmission components, restricting suspension types and increasing device length.
Innovation Solution
The electric vehicle driving device features a configuration where the rotation axes of the first and second motors and the transmission device are positioned to avoid overlap, allowing for a reduction in axial length by using separate reduction gears to amplify torque and a connector placement that simplifies wiring, enabling efficient torque transmission and gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the driving device is designed with overlapping motor and transmission components in the axial direction, then the axial length is reduced, but the device complexity and wiring complexity increase
Solution Approach 1:
The patent transitions from a conventional axial stacking arrangement to a radial distribution arrangement where motors are positioned at different radial locations around the output member. This dimensional change allows components to be distributed in the radial plane rather than compressed axially, reducing wiring complexity while maintaining compact overall dimensions.
2Length of moving object
If the outer diameters of the motors are reduced to fit more components, then the axial length decreases, but the torque output capability is limited
Solution Approach 1:
The patent divides the drive system into multiple independent motor units (first motor and second motor) positioned at different radial locations. Each motor can be optimized for specific torque requirements, and their combined output provides sufficient total torque while maintaining reduced axial length through radial distribution.
Solution Approach 2:
The patent implements a nested arrangement where reduction gears are positioned within the radial space between the motors and the output member. This nesting allows torque amplification components to be integrated into the existing radial layout without increasing axial length, enabling reduced motor diameters while maintaining torque output capability.
3Power
If reduction gears are added to amplify torque, then the torque output increases, but the device complexity and axial length increase
Solution Approach 1:
The patent positions reduction gears in the radial dimension rather than extending them axially. The reduction gears are arranged to engage with motor shafts and transmit torque to the output member through radial gear trains, allowing torque amplification without increasing axial length.
4Ease of operation
If the connector is placed in the larger region for transmission device access, then the wiring space is reduced, but the wiring arrangement becomes difficult
Solution Approach 1:
The patent strategically places the connector in the smaller region where wiring requirements are less demanding. This local optimization considers the specific wiring needs of each motor location and positions the connector where it can efficiently serve both motors with minimal wiring complexity, rather than placing it where space is more abundant but wiring paths are more complex.
Data Source
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AI summary
An electric vehicle driving device includes a first motor, a second motor, a transmission device to which power of at least one of the first motor and the second motor is transmitted, and an output member that rotates with power output from the transmission device. A rotation axis of the first motor, a rotation axis of the second motor, and a rotation axis of the transmission device are arranged in parallel to a rotation axis of the output member. When seen from an axial direction parallel to the rotation axis of the output member, the rotation axis of the first motor is located on one side of a straight line passing through the rotation axis of the output member and the rotation axis of the transmission device and the rotation axis of the second motor is located on the other side of the straight line.