Dual-Motor Vehicle Drive Unit With Nested Shafts and Shift Decoupling
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Solution Overview
Problem
Existing drive units for vehicles are not compact and efficient, particularly in integrating multiple electrical machines and gear systems, leading to inefficiencies and increased space requirements.
Innovation Solution
A drive unit design featuring two electrical machines, a manual gearbox with two gears, a differential, and positive-locking shift units, including a first shift unit with a sliding sleeve and actuator, and a second shift unit with a sliding sleeve, allowing for compact arrangement and efficient torque distribution and decoupling of electrical machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple electrical machines and gear systems are integrated into a drive unit, then functionality and versatility are improved, but device complexity and space requirements increase
Solution Approach 1:
The output shaft is arranged within the hollow drive shaft, creating a nested configuration where the output shaft passes through the interior cavity of the drive shaft. This nesting principle allows two shafts to coexist in a compact arrangement, reducing the overall radial dimension of the drive unit while maintaining multiple functional pathways for torque transmission.
Solution Approach 2:
The patent utilizes axial parallel arrangement of the two electrical machines and their respective shafts, transitioning from a traditional radial or stacked configuration to an axial layout. This dimensional reorganization allows the first electrical machine and drive shaft to be positioned axially parallel to the second electrical machine and output shaft, optimizing space utilization and reducing device complexity.
2Loss of energy
If positive-locking shift units are used instead of friction-locking shift elements, then efficiency is improved due to reduced drag losses, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces friction-locking shift elements with positive-locking shift units that utilize mechanical engagement through claw-toothed interfaces. This substitution eliminates reliance on friction-based torque transfer, thereby reducing drag losses and improving efficiency. The positive-locking mechanism provides direct mechanical coupling between shafts, ensuring reliable torque transmission with minimal energy loss.
3Volume of moving object
If the output shaft is guided axially through the entire drive shaft, then compactness is improved, but structural complexity increases
Solution Approach 1:
The output shaft is positioned within the hollow interior of the drive shaft, creating a nested configuration that maximizes spatial efficiency. This arrangement allows the output shaft to pass axially through the drive shaft's cavity, enabling compact packaging of multiple transmission pathways without increasing the overall radial footprint of the drive unit.
Solution Approach 2:
The hollow drive shaft structure serves multiple functions: it acts as a structural support element, provides a protective enclosure for the output shaft, and creates a defined pathway for torque transmission. This multi-functional design reduces the need for additional separate components, thereby managing structural complexity while achieving compactness.
Data Source
AI summary
A vehicle drive unit has a first and second electrical machines arranged in parallel, a manual gearbox arranged parallel to the electrical machines, a differential, a hollow drive shaft for connecting the first electrical machine to the gearbox, an output shaft within the drive shaft and for connecting the gearbox to the differential. A positive-locking shift unit has first and second shift elements and a sliding sleeve that is displaceable into three shift positions. In a first shift position, the first shift element is closed, and the second electrical machine is connected to the drive shaft with an actuating effect. In a second shift position, both shift elements are open, and the second electrical machine is decoupled from the gearbox. In a third shift position, the second shift element is closed, and the second electrical machine is connected to the output shaft with an actuating effect.