Dual-Motor Electric Transmission With Load-Shiftable Range Gears
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Solution Overview
Problem
Existing purely electric drive systems for vehicles lack efficient and comfortable operation, particularly in commercial vehicles, due to limitations in gear shifting and starting performance, which are not adequately addressed by hybrid systems.
Innovation Solution
A purely electric drive system utilizing two electric motors with a group transmission featuring a main gear and range group with a planetary gear set, including exactly two idler gears on each input shaft for discrete shiftable gears and virtual intermediate gears, allowing for load shiftability and reduced wear through claw switching elements, and a compact design with fixed gear connections to the planetary gear set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a purely electric drive system uses a single motor with traditional gear shifting, then the structure is simple, but starting performance and gear shifting comfort are insufficient
Solution Approach 1:
The transmission system is segmented into two independent motor-input shaft configurations, allowing each motor to independently control specific gear ranges. This segmentation enables optimized starting performance through the first motor while the second motor handles higher gear ranges, resolving the contradiction between improved starting performance and structural complexity.
Solution Approach 2:
Two idler gears are introduced as intermediary elements between the motors and the fixed gears. These idlers enable smooth gear shifting by acting as mediators that can be selectively engaged or disengaged, improving gear shifting comfort while maintaining a manageable transmission structure.
2Ease of operation
If friction shift elements are used for gear shifting, then gear shifting is possible, but wear occurs and service life is reduced
Solution Approach 1:
The patent replaces friction-based shift elements with claw switching elements that engage gear teeth through positive mechanical engagement. This substitution eliminates wear associated with friction, allowing gear shifting to occur while significantly extending the service life of the transmission components.
Solution Approach 2:
The gear shifting mechanism is designed to be dynamically controllable, with the ability to shift gears under load through coordinated motor control. The system can adjust motor speeds to synchronize gear engagement, enabling smooth shifting without requiring the transmission to be idle, thus improving ease of operation while maintaining reliability.
3Use of energy by moving object
If one motor is shut down during partial load operation, then efficiency and lifespan are improved, but the system loses operational flexibility
Solution Approach 1:
The system dynamically adjusts the number of active motors based on load conditions. During partial load operation, one motor can be shut down to improve energy efficiency, while the system maintains operational flexibility by being able to activate both motors when higher power is needed. The control system seamlessly manages the transition between single-motor and dual-motor operation.
Solution Approach 2:
The system changes operational parameters by switching between different motor configurations (one motor active vs. both motors active) based on load requirements. This parameter change enables the system to optimize energy efficiency during partial load while maintaining the adaptability to provide full power when necessary, resolving the contradiction between efficiency and flexibility.
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 enables comfortable, efficient, and long-lasting operation by improving starting performance and reducing wear, particularly in heavy vehicles, with one motor able to be shut down during partial load operation, extending lifespan and efficiency.
Implementation Method 1
a range group (9), in particular with a planetary gear set (10)
Data Source
Figure 1~2
AI summary
The invention relates to a purely electric drive system (1) having two electric machines (2,3) and a group transmission (7) having a main group (6) and a range group (9), the range group (9) having a planetary gear (10), wherein a first input shaft (4) of the main group (6) is or can be coupled to the first electric machine (2) such that torques from the first electric machine (2) can be introduced into the group transmission (7) via the first input shaft (4), wherein a second input shaft (5) of the main group (6) is or can be coupled to the second electric machine (3), wherein an output shaft (8) of the main group (6) is coupled permanently in a torque-transmitting manner to a first element (26) of the planetary gear (10), and wherein a second element (12) of the planetary gear is coupled permanently in a torque-transmitting manner to an output shaft (13) of the group transmission (7). The invention is characterized in that exactly two idler gears (18, 19) are arranged coaxially with the first input shaft (4), wherein exactly two further idler gears (20, 21) are arranged coaxially with the second input shaft (5), wherein the two input shafts (4, 5) are or can be coupled to the output shaft (8) via exactly two fixed gears (22, 23) arranged coaxially with the output shaft (8), and wherein a first fixed gear (22) is permanently in meshing engagement with the first and the third idler gear (18, 20) and a second fixed gear (24) is permanently in meshing engagement with the second idler gear (19) and the fourth idler gear (21).