Electric Drive Axle Sliding-Sleeve Coupling for Axle Decoupling
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Solution Overview
Problem
Existing electric drive axles for two-track motor vehicles face inefficiencies due to the need for multiple switching elements and the inability to decouple the gearbox and differential, leading to reduced drive efficiency.
Innovation Solution
The integration of a connecting element that firmly connects two sliding sleeves, allowing for simultaneous switching and enabling decoupling or coupling of driven gears between half-shafts and driven wheels through a single switching element with three switching positions, including a third position for complete axle lock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple switching elements are used to connect electric motors to half-shafts and output gears, then the drive can be switched between different operating modes (driving, regenerative braking, mechanical decoupling), but the device complexity increases and drive efficiency decreases due to additional friction and switching losses
Solution Approach 1:
The patent combines multiple switching functions into a single switching element that can connect/disconnect both the electric motor from the half-shaft and the output gear from the half-shaft simultaneously. This merging of functions reduces the total number of switching elements from multiple separate clutches to one integrated switching mechanism, thereby reducing device complexity while maintaining the ability to switch between driving, regenerative braking, and mechanical decoupling modes.
Solution Approach 2:
The single switching element is designed to perform multiple functions: it can disconnect the electric motor from the half-shaft, disconnect the output gear from the half-shaft, and enable mechanical coupling between the half-shaft and wheels. This multi-functional design allows one component to replace what would traditionally require multiple separate switching elements, reducing overall system complexity.
2Device complexity
If the transmission and differential are permanently coupled, then the mechanical structure is simplified, but drive efficiency is reduced due to constant drag when the drive axle is not needed
Solution Approach 1:
The patent introduces a dynamic switching capability that allows the transmission and differential to be mechanically decoupled from the half-shafts when the drive axle is not needed. The switching element can disengage the output gears from the half-shafts, creating a mechanical disconnect that eliminates constant drag and energy losses. This dynamic on-demand engagement/disengagement resolves the contradiction by allowing structural simplicity when engaged while preventing energy losses when disengaged.
3Device complexity
If a mechanical differential gear is used to compensate for speed differences at wheels, then the drive system is simplified compared to two separate electric motors, but torque vectoring capability is reduced to a fixed 50:50 split
Solution Approach 1:
The patent enables dynamic torque distribution by allowing independent control of each half-shaft through the switching element. By mechanically decoupling the half-shafts from the output gears when needed, the system can apply brake torque to one wheel while maintaining drive torque to the other, achieving active torque vectoring. This dynamic switching capability provides adaptability in torque distribution that a fixed mechanical differential cannot achieve.
Data Source
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AI summary
The invention relates to an electric drive axle (1) for a two-track motor vehicle, comprising a first half-shaft (2a) for driving a first wheel (3a) and a second half-shaft (2b) for driving a second wheel (3b) of the motor vehicle, wherein the first half-shaft (2a) can be driven via a first output wheel (4a) by a first electric machine (5a) and the second half-shaft (2b) can be driven via a second output wheel (4b) by a second electric machine (5b), wherein at least one electric machine (5a, 5b) can be connected to a wheel (3a, 3b) via a switching element (6).wherein the switching element (6) comprises at least one first sliding sleeve (6a) arranged coaxially to the first half-shaft (2a) in a first drive path between the first output gear (4a) and the first half-shaft (2a) and axially displaceable, and at least one second sliding sleeve (6b) arranged coaxially to the second half-shaft (2b) in a second drive path between the second output gear (4b) and the second half-shaft (2b) and axially displaceable. High drive efficiency can be achieved if the first sliding sleeve (6a) and the second sliding sleeve (6b) are rigidly connected to each other via a connecting element (62c).