Variable Spring Stiffness for Rail Vehicle Traction
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Solution Overview
Problem
Existing rail vehicle systems face reduced tractive effort due to loss of proper traction during inclement weather or adverse rail conditions, as preloaded springs fail to maintain adequate contact between wheels and tracks, especially in heavy trains or uphill starts.
Innovation Solution
Implementing a system with variable spring stiffness, where a motor-controlled spring retainer adjusts the number of inactive coils in the suspension springs to dynamically redistribute load among axles, increasing traction by transferring weight from inner to outer axles, thereby enhancing contact and reducing wheel slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If preloaded springs are used in the suspension system, then the normal weight distribution is maintained under normal conditions, but the springs cannot provide sufficient normal force to maintain proper wheel-track contact during inclement weather or adverse rail conditions
Solution Approach 1:
The spring stiffness is made dynamically adjustable through a mechanism that can change the number of active coils in the springs. This allows the suspension system to adapt from a static preloaded state to a dynamic state where stiffness can be modified in response to varying operational conditions, resolving the contradiction between maintaining reliable contact and adapting to different scenarios.
Solution Approach 2:
The invention changes the physical parameter of spring stiffness by altering the number of active coils. This parameter change enables the springs to provide variable force characteristics - maintaining normal weight distribution under standard conditions while being capable of providing enhanced normal force when needed for improved wheel-track contact during adverse conditions.
2Force
If the number of active coils in the springs is reduced to increase stiffness, then the normal force increases improving wheel contact, but the device complexity increases due to the spring retainer mechanism
Solution Approach 1:
The spring retainer mechanism is nested within the existing suspension assembly, with the retainer fitting inside or around the spring structure. This nesting approach allows the complexity to be contained within a compact form factor, minimizing the increase in overall device complexity while still enabling the force adjustment capability.
Solution Approach 2:
The spring retainer mechanism is designed to be actuated by the existing motor and controller systems already present in the rail vehicle, rather than requiring entirely new actuation mechanisms. This self-service approach leverages existing components to reduce the overall complexity increase associated with the variable stiffness capability.
3Power
If weight is transferred from inner to outer axles to increase traction, then the tractive effort is improved, but the load distribution becomes non-uniform affecting vehicle stability
Solution Approach 1:
The weight transfer is applied locally to specific axles (outer axles) rather than uniformly across all axles. This local quality approach allows targeted increase in tractive effort where it is most needed for propulsion, while maintaining different load characteristics on inner axles that may be better suited for guidance and stability functions.
Solution Approach 2:
The load distribution is made dynamic rather than static, allowing the vehicle to adjust weight distribution in real-time based on operational conditions. This dynamic capability enables the system to optimize the balance between tractive effort and stability, transferring weight to outer axles when maximum traction is needed while maintaining more uniform distribution when stability is the priority.
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 increases traction and allows for heavier loads to be hauled with fewer traction motors, improving contact between wheels and rails, and reducing wheel slip during traction-limited operations.
Implementation Method 1
a motor connected to the plurality of spring retainers and configured to actuate the spring retainers to adjust the number of inactive coils of the plurality of springs
Implementation Method 2
a plurality of springs and a plurality of spring retainers configured to adjust a number of inactive coils of the plurality of springs
Data Source
AI summary
Systems and methods provide variable spring stiffness for weight management in a vehicle. One system includes a plurality of springs and a plurality of spring retainers configured to adjust a number of inactive coils of the plurality of springs. Additionally, a motor is provided that is connected to the plurality of spring retainers and configured to actuate the spring retainers to adjust the number of inactive coils of the plurality of springs. Further, a controller is provided that is coupled to motor to control the motor to actuate the spring retainers to adjust the number of inactive coils of the plurality of springs.