Carriage Coupling Torque Profile for Smoother Rail Curve Entry
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Solution Overview
Problem
Existing rail vehicles, particularly multi-articulated low-floor trams, experience curve negotiation issues due to car centers of gravity located forward of bogie centers, leading to abrupt steering forces when entering curves, which affect driving safety and comfort.
Innovation Solution
A rail vehicle with a car articulation device that provides a variable resistance torque gradient, increasing at smaller angular positions and decreasing at larger angular positions during curve entry, allowing lateral forces to be transferred between cars for stabilization, using springs and dampers or geometrically defined cam bodies to adjust resistance torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the car articulation device provides high resistance torque at all angular positions to stabilize the vehicle, then the derailment stability is improved, but the ability of the first car to turn into curves is impeded and excessive steering forces occur
Solution Approach 1:
The car articulation device employs a variable resistance torque that dynamically changes with the angular position between cars. At small angular positions (straight or slightly curved track), the resistance torque is high to provide stability. As the angular position increases (entering curves), the resistance torque decreases to allow smooth curve negotiation. This dynamic adaptation resolves the contradiction between stability and maneuverability.
Solution Approach 2:
The invention changes the parameter of resistance torque from a constant value to a variable value that depends on the angular position. By defining different resistance torque gradients for different angular ranges, the system optimizes both stability during straight travel and ease of curve entry, eliminating the trade-off between these opposing requirements.
2Device complexity
If the car articulation device has constant resistance torque to simplify the design, then the device complexity is reduced, but the driving comfort and safety during curve entry deteriorate due to abrupt steering forces
Solution Approach 1:
Rather than using a complex active control system with sensors and actuators, the invention achieves dynamic resistance torque adjustment through a passive mechanical design. The resistance torque naturally varies with angular position through the geometric configuration of the articulation device, maintaining simplicity while improving driving comfort.
Solution Approach 2:
The car articulation device automatically adjusts its resistance torque based on the angular position between cars without requiring external control inputs. The system self-regulates by transferring lateral forces between cars in a way that naturally reduces steering forces during curve entry, eliminating the need for complex control systems.
3Stability of the object's composition
If the car articulation device transfers lateral forces between cars to improve stability, then the derailment stability increases, but the steering forces between wheelsets and track increase excessively
Solution Approach 1:
The invention applies different resistance torque characteristics to different angular position ranges. In the range of small angular positions, high resistance torque provides stabilization by transferring lateral forces between cars. In the range of large angular positions (curve entry), the resistance torque gradient is reduced to minimize steering forces at the wheelsets, achieving local optimization of force distribution.
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
Improves driving dynamics during curve entry maneuvers by stabilizing the vehicle without impeding its ability to turn, enhancing safety and comfort by reducing excessive steering forces.
Implementation Method 1
a first spring (8) which is connected to the at least first carriage (1) and the second carriage (2), wherein a first normal distance (14) between a first longitudinal axis (10) of the first spring (8) and a pivot point (7) is variable
Implementation Method 2
The carriage articulation device (5) has damping on both sides
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a rail vehicle having at least a first carriage (1) and a second carriage (2) which are coupled to one another by means of a carriage coupling device (5), the carriage coupling device (5) having a variable resistance to twisting of the at least first carriage (1) relative to the second carriage (2). According to the invention, a first resistance torque gradient (25) of the carriage coupling device (5) at a first angular position (16) of the at least first carriage (1) relative to the second carriage (2) in a direction of rotation is greater in magnitude than a second resistance torque gradient (26) of the carriage coupling device (5) at a second angular position (17) of the at least first carriage (1) relative to the second carriage (2) in the same direction of rotation, the first angular position (16) being associated with a lesser twisting of the at least first carriage (1) relative to the second carriage (2) than the second angular position (17). In this way, an improved driving behaviour of the rail vehicle is achieved, in particular when entering track curves.