Ball-Shaped Differential Nested in Planetary Gear Electric Drive
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Solution Overview
Problem
Existing electric drive devices for motor vehicles face challenges in achieving a compact design and efficient operation, particularly in managing speed compensation and torque transmission between wheels during cornering while minimizing power loss.
Innovation Solution
The electric drive device incorporates a ball-shaped differential gear with a bevel gear differential housing, coaxially arranged with planetary gear sets and an electric motor, featuring switching elements for non-rotatable connections and axial bearings to support components, enabling efficient speed compensation and torque transmission while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional differential gear arrangement is used, then speed compensation between wheels is achieved, but the device occupies excessive installation space and has increased weight
Solution Approach 1:
The differential gear is nested within the planetary gear set structure. The differential housing is integrated with the planetary gear components, allowing the differential mechanism to occupy space within the existing gear assembly rather than requiring separate mounting space. This nesting approach reduces the overall volume of the drive device while maintaining the speed compensation function.
Solution Approach 2:
The patent combines the differential gear mechanism with the planetary gear set into a single integrated assembly. The differential housing, planetary gears, and carrier are merged into one compact unit, eliminating the need for separate differential and transmission housings. This merging reduces installation space and simplifies the overall structure.
2Adaptability or versatility
If multiple switching elements are added for non-rotatable connections, then gear range switching capability is improved, but device complexity increases
Solution Approach 1:
The switching elements are designed to perform multiple functions. Each switching element not only engages/disengages gear ranges but also serves as a structural support component and torque transmission path. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in device complexity.
Solution Approach 2:
The transmission system is segmented into distinct gear ranges (first, second, third, and fourth ranges) with dedicated switching elements for each. This segmentation allows independent control of each gear range, improving adaptability while keeping the control logic simple and modular, which helps manage device complexity.
3Volume of moving object
If the side shaft runs inside the rotor, then compact coaxial arrangement is achieved, but manufacturing and assembly difficulty increases
Solution Approach 1:
The side shaft is nested within the rotor structure, running coaxially through the rotor's interior space. This nesting arrangement achieves compact coaxial alignment of the differential, planetary gears, and motor components without requiring additional external mounting space, thus reducing overall device volume while maintaining manufacturability.
Data Source
AI summary
An electric drive device has a planetary gear set, which includes has a first sun gear, a first planet carrier and a first ring gear. The drive device also includes a planetary gear set with a second sun gear that is or can be non-rotatably coupled to the first ring gear, a second planet carrier and a second ring gear that is or can be non-rotatably coupled to the first planet carrier. An electric motor has a rotor with an input shaft driveable by the rotor and permanently non-rotatably connected to the first sun gear. The drive device also includes an output shaft, a differential gear, a first switching element, and a second switching element. The planetary gear sets are arranged coaxially to the differential gear and the differential gear has a ball-shaped differential having a differential housing.