Nested Differential Transmission 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 and low-loss design while maintaining advantageous functionality, particularly in terms of switchability and torque transmission efficiency.
Innovation Solution
The electric drive device incorporates a housing with a first and second planetary gear set, a differential transmission arranged radially within these sets, and a translation stage axially positioned between the electric machine and the differential gear, along with a connecting body and additional bearing elements to enhance compactness and performance, utilizing a blocking switching element for efficient torque transfer and switchability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional electric drive device is designed with standard component arrangements, then the basic functionality is achieved, but the device size and weight are larger than necessary
Solution Approach 1:
The differential transmission is arranged radially within the planetary gear sets, with the differential basket positioned inside the radial space of the planetary components. This nesting approach allows the differential transmission to occupy the radial space between the sun gear and planet gears, significantly reducing the overall device volume without adding axial height or radial footprint.
Solution Approach 2:
The differential transmission is positioned in the radial dimension rather than the axial dimension, where it would traditionally be placed. This dimensional reorganization allows the differential basket to be located within the radial clearance of the planetary gear set, enabling a more compact three-dimensional layout that reduces overall device size.
2Ease of manufacture
If multiple separate components are used for torque transmission and switching, then the functionality is complete, but the parts number and costs increase
Solution Approach 1:
The blocking switching element is integrated directly into the planetary gear set structure, with its blocking positions aligned with the planet carriers. This merging of the switching mechanism with the torque transmission components eliminates the need for separate switching devices, reducing parts number and manufacturing cost while maintaining reliable torque transmission through the unified structural design.
Solution Approach 2:
The planetary gear set components serve multiple functions: they provide torque transmission through gear meshing, enable switching through the integrated blocking switching element, and support the differential transmission. This multi-functionality reduces the need for separate dedicated components, lowering manufacturing costs while ensuring reliable torque transmission through the versatile planetary mechanism.
3Volume of moving object
If the blocking switching element is integrated within the planetary gear set, then the device becomes more compact, but the switching mechanism complexity increases
Solution Approach 1:
The blocking switching element is divided into multiple blocking positions, each associated with specific planet carriers. This segmentation allows the switching mechanism to be distributed across different radial positions within the planetary gear set, reducing the complexity of any single switching position while maintaining overall compactness through the distributed arrangement.
Data Source
Figure 1
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AI summary
The invention relates to an electric drive device, having a housing (12), having an electric machine (74), having a differential transmission (42) and having a transmission device (10), which has: a first planetary gear set (14) which is accommodated in the housing (12) and which has a first sun gear (16), a first internal gear (18) and a first planet carrier (20); and a second planetary gear set (24) which is accommodated in the housing (12) and which has a second sun gear (26) connected or connectable rotationally conjointly to the housing (12), a second internal gear (28) connected or connectable rotationally conjointly to the first planet carrier (20), and a second planet carrier (30), wherein the first sun gear (16) is connected or connectable rotationally conjointly to the second sun gear (26), wherein the differential transmission (42) is arranged radially within the first planetary gear set (14) and the second planetary gear set (24) and axially in the region of the first planetary gear set (14) and of the second planetary gear set (24), and wherein the second planet carrier (30) is connected rotationally conjointly to a differential cage (78).