Rail Vehicle Compact Direct Drive Motor Suspension
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Solution Overview
Problem
Compact traction drives in rail vehicles face challenges with high unsprung mass, leading to increased track loads and shock loads, which complicates maintenance and increases construction costs.
Innovation Solution
A rail vehicle design where the drive motor is suspended at a single point on the chassis with a single-plane clutch, allowing movement in the direction of rotation and transversely, and supported via a link for torque, reducing the need for additional coupling levels and hollow shafts, thus minimizing unsprung mass and optimizing space utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the drive motor is mounted directly on the wheelset axle (axle-hung drive), then the drive becomes compact and space is saved, but the unsprung mass increases leading to high track stresses and shock loads
Solution Approach 1:
The drive motor is arranged radially around the wheelset axle in a radial configuration, utilizing the radial dimension rather than just axial or lateral dimensions. This allows compact packaging of the drive motor while keeping it suspended from the chassis, thereby achieving space efficiency without increasing unsprung mass.
Solution Approach 2:
A coupling device serves as an intermediary between the suspended drive motor and the wheelset axle. The coupling transmits torque while allowing the drive motor to remain suspended from the chassis, enabling both compact arrangement and reduced unsprung mass through this mediating component.
2Weight of moving object
If the drive motor is suspended from the chassis on both sides (floating drive), then unsprung mass is minimized, but the device complexity increases with multiple buffer and coupling elements
Solution Approach 1:
The drive motor is suspended from a single point on the chassis rather than both sides, extracting the need for symmetric dual-side suspension elements. This simplifies the suspension structure while still achieving minimized unsprung mass through the single-point suspension combined with radial arrangement.
Solution Approach 2:
The coupling device combines multiple functions: it transmits torque from the drive motor to the wheelset axle, accommodates the radial arrangement of the motor, and works with the single-point suspension system. This merging of functions reduces the overall number of separate components needed compared to traditional floating drive configurations.
3Power
If traditional multi-level coupling and hollow shafts are used, then torque transmission is achieved, but the drive train becomes less compact and space utilization decreases
Solution Approach 1:
The coupling device utilizes a radial arrangement where the drive motor surrounds the wheelset axle radially. This radial dimension allows direct torque transmission paths that eliminate the need for multi-level axial couplings and hollow shafts, achieving compact packaging while maintaining effective torque transmission.
Solution Approach 2:
The complex multi-level mechanical coupling system with hollow shafts is replaced by a simplified coupling device that directly connects the radially arranged drive motor to the wheelset axle. This substitution reduces the mechanical complexity and volume while maintaining torque transmission capability.
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 design results in a statically fully sprung drive with reduced load on the clutch and wheelset shaft, lower dynamic wheel-rail forces, and increased spring deflection, while maintaining ground clearance and allowing for more powerful motors within the same installation space.
Implementation Method 1
The suspension of the drive motor on the chassis is designed in such a way that it allows movement of the drive motor both in the direction of the axis of rotation of the wheelset axle and transversely thereto
Implementation Method 2
the drive motor is additionally connected to the chassis via at least one link for torque support
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
A rail vehicle has a chassis (2) in which a wheelset axle (3) is spring-mounted, so that the wheelset axle (3) can rotate about an axis of rotation (7) and the chassis (2) is a sprung mass with respect to the wheelset axle (3). A drive motor (8) for the wheelset axle (3) acts on the wheelset axle (3) via a coupling (9). The drive motor (8) surrounds the wheelset axle (3). The coupling (9) is designed as a single-plane coupling. The drive motor (8) is directly connected to the coupling (9) and, viewed in the direction (y) of the axis of rotation (7) of the wheelset axle (3), is suspended at a single point on the chassis (2). The suspension of the drive motor (8) on the chassis (2) is designed such that it allows movement of the drive motor (8) both in the direction (y) of the axis of rotation (7) of the wheelset axle (3) and transversely thereto.