Multi-Speed Electric Drive Axle With Compact Nested Clutch Gearbox
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Solution Overview
Problem
Conventional electric drive axles for vehicles are large and heavy, making them inefficient in terms of size, weight, and production costs, which hinders their ability to provide reasonable power over a broad speed range.
Innovation Solution
The electric drive axle design incorporates a multi-speed gearbox system with a clutch assembly and gear train configuration that includes a first and second clutch assembly, with a hydraulic actuator for engaging and disengaging the clutches, allowing for efficient torque transfer and gear ratio selection, thereby reducing size and weight while maintaining performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-speed electric motor is used to provide power over a broad speed range, then the motor can achieve reasonable power across different speeds, but the motor becomes large and heavy
Solution Approach 1:
The single-speed motor is replaced by a multi-speed gearbox system with multiple gear sets (first gear set with first and second gears, third gear, fourth gear; second gear set with fifth gear, sixth gear). This segmentation allows the motor to operate at optimal speed while the gearbox provides multiple speed ratios, effectively dividing the broad speed range into manageable segments handled by different gear combinations.
Solution Approach 2:
The gearbox incorporates clutch assemblies (first clutch with first clutch drum, second clutch with second clutch drum) that enable dynamic switching between different gear ratios. This dynamic reconfiguration allows the system to adapt to varying speed requirements without changing the motor itself, maintaining motor optimality while achieving broad speed range coverage.
2Adaptability or versatility
If a single-speed electric motor is used to provide power over a broad speed range, then the motor can achieve reasonable power across different speeds, but the overall system size and weight increase
Solution Approach 1:
The clutch drums are disposed concentrically within each other (first clutch drum nested within second clutch drum), and the gear sets are arranged in a compact configuration where gears are meshed in series. This nesting arrangement minimizes the radial and axial space required for the gearbox, reducing overall drive axle volume while maintaining multiple speed ratios.
Solution Approach 2:
The offset idler shaft arrangement and concentric clutch drum configuration utilize three-dimensional space efficiently. By arranging components in multiple dimensions (offset shafts, concentric drums, stacked gear sets), the design achieves compact packaging that reduces overall system volume while maintaining functional requirements for broad speed range.
3Weight of moving object
If a multi-speed gearbox with clutch assemblies is implemented, then the system size and weight are reduced, but the device complexity increases
Solution Approach 1:
The clutch assemblies serve multiple functions: they engage and disengage different gear ratios, provide neutral position control, and enable smooth transitions between speed ranges. The offset idler shaft system universally handles torque transmission across all gear sets. This multi-functionality reduces the need for separate control mechanisms, managing complexity while maintaining versatility.
Solution Approach 2:
The clutch drums act as intermediaries between the motor shaft and the various gear sets. Rather than directly connecting the motor to multiple gear ratios, the clutch drums mediate the engagement, simplifying the control architecture. The hydraulic actuators serve as intermediaries for clutch actuation, providing smooth and controlled engagement without requiring complex mechanical linkages.
4Power
If conventional electric drive axles are used, then they can provide drive power, but production costs are high due to large size and weight
Solution Approach 1:
The invention changes the fundamental parameters of the drive system by introducing a multi-speed gearbox with specific gear ratios and clutch engagement characteristics. This parameter change allows the motor to operate at higher efficiency points while delivering the required power across a broad speed range, reducing the overall motor size and associated costs. The compact gearbox design also reduces material requirements and manufacturing complexity compared to conventional single-speed systems.
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 a compact and lightweight electric drive axle that efficiently provides power over a broad speed range, reducing production costs and enhancing vehicle performance.
Implementation Method 1
a hydraulic actuator for engaging and disengaging the clutches
Implementation Method 2
A third gear is selectively coupled with the second shaft, and the third gear is meshed with the first gear
Data Source
AI summary
An electric drive axle including a first shaft in driving engagement with an electric motor. A first gear and a second gear are coupled with the first shaft. A second shaft is disposed offset from the first shaft. A third gear is selectively coupled with the second shaft, and the third gear is meshed with the first gear. A fourth gear is selectively coupled with the second shaft, and the fourth gear is meshed with the second gear. A fifth gear is coupled with the second shaft and meshed with a sixth gear coupled with a differential case.