Compact Traction Drive Unit With High-Speed Motor And Passive Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing traction drive units for rail vehicles are bulky and heavy due to direct coupling between motors and wheels/axles, limiting their power output and making it impossible to achieve a compact, low-floor design, especially at higher power applications, as they are designed for lower speeds and do not allow the use of high-speed motors.
Innovation Solution
A compact traction drive unit with a high-speed electrical motor exceeding 9,000 rpm, integrated into a single housing with a two-stage gearbox, enabling significant reduction in volume and weight by using passive cooling and preheating the lubricant for low temperatures, allowing the integration of all components into a single compact housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct coupling between motor and wheel is used, then power transmission is simplified, but weight and volume of the drive unit increase significantly
Solution Approach 1:
A flexible coupling shaft with universal joints is introduced as an intermediary element between the motor and wheel. This coupling shaft transmits rotational motion while accommodating misalignments and reducing the need for heavy direct coupling mechanisms, thereby decreasing drive unit weight while maintaining power transmission functionality.
Solution Approach 2:
The drive unit is segmented into modular components: motor, flexible coupling shaft with universal joints, and wheel assembly. This segmentation allows each component to be optimized independently, reducing overall weight by eliminating the need for a single heavy integrated coupling structure.
2Weight of moving object
If high-speed electrical motor is used, then volume and weight of drive unit are reduced, but lubricant preheating system is required for low temperature operation
Solution Approach 1:
The lubricant preheating system activates before the drive unit operates in cold conditions, pre-warming the lubricant to ensure proper viscosity and flow characteristics. This preliminary action prevents operational issues at low temperatures without requiring a complex heating system during normal operation.
Solution Approach 2:
The high-speed motor's own operational heat gradually warms the lubricant during initial operation, reducing the need for external heating systems. The system leverages the motor's inherent thermal output to maintain lubricant temperature, minimizing additional complexity.
3Volume of moving object
If passive cooling system is implemented, then drive unit volume is reduced by eliminating fans, but heat dissipation efficiency must be maintained
Solution Approach 1:
The passive cooling system replaces active mechanical cooling components (fans) with thermally conductive structures and heat dissipation pathways integrated into the housing. Heat is transferred from the motor to the housing and dissipated to the surrounding air through conduction and natural convection, eliminating the need for mechanical fans and reducing volume.
4Ease of manufacture
If two-stage gearbox is integrated into single housing, then assembly is simplified, but manufacturing precision requirements increase
Solution Approach 1:
The two-stage gearbox is merged into a single integrated housing structure, combining the first and second gearboxes with their respective bearings and shafts into one unified assembly. This integration simplifies assembly by reducing the number of separate components and connection points, while precision features are built into the housing design.
Solution Approach 2:
The housing incorporates precision-engineered mounting surfaces, alignment features, and tolerance-controlled dimensional parameters that ensure accurate positioning of gearbox components. By controlling key geometric parameters during manufacturing, the integrated design achieves the required precision without complicating assembly.
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 solution reduces the volume and weight of the drive unit by 25% while maintaining traction power, simplifies assembly, and eliminates the need for fans, providing efficient heat dissipation and cost savings through passive cooling.
Implementation Method 1
A compact traction drive unit with a high-speed electrical motor exceeding 9,000 rpm
Implementation Method 2
providing efficient heat dissipation and cost savings through passive cooling
Implementation Method 3
passive cooling
Implementation Method 4
preheating the lubricant for low temperatures
Data Source
AI summary
A compact drive unit is predominantly intended for traction vehicles, especially for rail vehicles. This invention allows significant reduction of volume and weight of drive units. The drive unit comprises high-speed electrical motor (1) with passive cooling, which is supplied by power electronics converter (2), whose rotor is supported by bearings (3) along with pinion gear (4) of the input spur/helical gear (5). The output shaft (6) of the gear (5) is a part of the next following gear (7). Output shaft of this gear (7) can be connected either directly or by using the coupling (12) to the axle (8) of the traction vehicle, or to the wheel (9). Alternatively, in case the higher transmission ratio is required, it can be connected to another gears (10), where the output shaft of the gears (10) is connected to the wheel (9), or to the axle (8) of the traction vehicle directly or by using the coupling (12). The drive unit can be equipped with brake (13).