Electric Drive Transmission Device Integrating Final Drive Function
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Solution Overview
Problem
Existing electric drive transmission devices for motor vehicles face challenges in achieving low-loss operation and compact design, often requiring additional components and space due to complex gear configurations.
Innovation Solution
The transmission device integrates a permanently non-rotatable coupling of the sun gear of the third planetary gearset to the ring gear of the second gearset and the output shaft, along with fixed couplings of planetary carriers to the housing, eliminating the need for a final drive and reducing the number of parts, weight, and space requirements, while utilizing friction and form-fitting clutches for shifting capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional transmission device with multiple planetary gear sets is used, then gear transmission capability is achieved, but the device complexity and space requirements increase
Solution Approach 1:
The patent merges the final drive function into the planetary gear set structure by permanently coupling the sun gear of the third planetary gear set to both the ring gear of the second planetary gear set and the output shaft. This integration eliminates the need for a separate final drive, reducing device complexity while maintaining complete gear transmission capability through the combined planetary gear system
Solution Approach 2:
The planetary gear sets are designed to perform multiple functions simultaneously. The third planetary gear set serves both as a transmission stage and as a final drive mechanism through its permanent coupling configuration. The ring gear of the second planetary gear set serves dual purposes as both a transmission element and a support structure for the third sun gear, enabling multi-functionality that reduces overall device complexity
2Reliability
If additional components like final drive are added to achieve complete power transmission, then transmission capability is improved, but weight and space requirements increase
Solution Approach 1:
The final drive function is merged into the existing planetary gear set structure through permanent couplings. The sun gear of the third planetary gear set is permanently coupled to both the ring gear of the second planetary gear set and the output shaft, eliminating the need for a separate final drive component. This integration achieves complete power transmission capability while minimizing additional weight
3Reliability
If additional components like final drive are added to achieve complete power transmission, then transmission capability is improved, but space requirements increase
Solution Approach 1:
The final drive function is merged into the existing planetary gear set structure through permanent couplings. The sun gear of the third planetary gear set is permanently coupled to both the ring gear of the second planetary gear set and the output shaft, eliminating the need for a separate final drive component. This integration achieves complete power transmission capability while minimizing additional space requirements
Solution Approach 2:
The planetary gear sets are arranged in a nested configuration where the third planetary gear set is positioned within or adjacent to the second planetary gear set. The permanent coupling of the third sun gear to the second ring gear creates a compact nested structure that achieves complete power transmission while minimizing the overall volume of the transmission device
Data Source
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AI summary
The invention relates to a transmission device (26) for an electric drive (10) of a motor vehicle, having a housing (30), having at least three planetary gear sets (32, 34, 36) which are arranged in the housing (30) and which have in each case one sun gear (38, 46, 54), one planet carrier (40, 48, 56) and one internal gear (42, 50, 58), having an input shaft (64) which can be driven by a rotor (20) of an electric machine (12), and having an output shaft (68), by means of which at least one wheel (14) of the motor vehicle can be driven, wherein at least one shift element (70) is provided, by means of which the internal gear (42) of a first of the planetary gear sets (32, 34, 36) can be fixed to the housing (30), wherein the internal gear (42) of the first planetary gear set (32) is permanently coupled rotationally conjointly to the sun gear (46) of a second of the planetary gear sets (32, 34, 36), wherein the internal gear (50) of the second planetary gear set (34) is permanently coupled rotationally conjointly to the planet carrier (40) of the first planetary gear set (32), and wherein the sun gear (54) of the third planetary gear set (36) is permanently coupled rotationally conjointly to the internal gear (50) of the second planetary gear set (34) and is permanently coupled rotationally conjointly to the output shaft (68).