Coaxial Planetary Transmission Input Shaft Integration
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Solution Overview
Problem
Existing motor vehicle transmission systems require significant axial installation space due to the coaxial arrangement of planetary transmissions, limiting compact design possibilities while aiming to implement multiple operating modes.
Innovation Solution
The planetary transmission is arranged coaxially with the first input shaft, with the carrier permanently coupled to one output shaft via a spur gear stage, allowing for shorter output shafts and reduced overall installation space, while enabling various shift conditions and operating modes such as electric, internal combustion engine-driven, and hybrid modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the planetary transmission is arranged coaxially to one of the output shafts, then the transmission can be designed with multiple operating modes, but the axial installation space requirement increases significantly
Solution Approach 1:
The planetary transmission is relocated from a coaxial arrangement with the output shaft to a coaxial arrangement with the input shaft, effectively changing the spatial dimension and reference axis for the planetary gear set. This dimensional repositioning allows the planetary transmission to utilize the axial space around the input shaft, thereby reducing the axial length requirement on the output shaft side while preserving all multiple operating modes (electric mode, internal combustion engine-driven mode, and hybrid mode).
2Length of stationary object
If the planetary transmission is arranged coaxially to the first input shaft with carrier permanently coupled via spur gear stage, then the axial installation space is reduced, but the device complexity increases due to additional gear stages
Solution Approach 1:
The spur gear stage serving as the permanent coupling between the planetary transmission carrier and the output shaft is designed to fulfill multiple functions simultaneously: it acts as both the power transmission element and the positioning/coupling mechanism. This multi-functionality reduces the need for separate coupling devices or additional shifting mechanisms, thereby limiting the increase in device complexity despite the rearranged configuration.
3Length of stationary object
If the output shafts are designed to be shorter to reduce installation space, then the axial space is optimized, but the torque transmission capability may be compromised
Solution Approach 1:
The planetary transmission, with its inherent torque multiplication capability through the gear ratio between ring gear and sun gear, performs the torque amplification action in advance before the power reaches the shortened output shafts. This preliminary torque multiplication allows the use of shorter output shafts while maintaining adequate torque transmission capability, as the high torque requirements are met at the planetary gear stage rather than requiring long output shafts for mechanical leverage.
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
This configuration achieves a compact transmission design that supports multiple operating modes with reduced axial space requirements, enabling efficient use of space on the first input shaft for the internal combustion engine and allowing for a speed superimposition mode and electrodynamic starting operation.
Implementation Method 1
The planetary transmission includes a ring gear, a sun gear, and a carrier. The ring gear of the planetary transmission forms the second input shaft of the transmission. The carrier of the planetary transmission is permanently coupled to one of the output shafts via a spur gear stage.
Implementation Method 2
a first prime mover (3), preferably designed as an internal combustion engine
Implementation Method 3
a second prime mover (4), preferably designed as an electric machine
Data Source
AI summary
A transmission (2) includes a first input shaft (7) for a first prime mover (3), a second input shaft (8) for a second prime mover (4), as well as a first output shaft (9) and a second output shaft (10), which are each coupleable to a drive output (11). A first sub-transmission (5) includes the first input shaft (7), and fixed gears (12, 13) are arranged on the first input shaft (7). Each of these fixed gears (12, 13) meshes with a respective idler gear (14, 15) on the first output shaft (9) and with a respective idler gear (16, 17) on the second output shaft (10). Shift elements (A, B, C, D) are associated with the output shafts (9, 10), depending on which the idler gears of the output shafts are coupleable to the particular output shaft in a rotationally fixed manner. A second sub-transmission (6) includes the second input shaft (8) and is designed as a planetary transmission. A ring gear (22) forms the second input shaft (8). A carrier (23) is coupled to one of the output shafts (9, 10). Shift elements (F, E) are associated with the planetary transmission, via which, depending on their shift position, the sun gear (24) is fixedly connectable to the housing or the planetary transmission is bringable into direct drive. The planetary transmission is arranged coaxially to the first input shaft (7). The carrier (23) of the planetary transmission is permanently coupled to one of the output shafts via a spur gear stage.