Rail Brake Deceleration Control with Dynamic Stroke Limits
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Solution Overview
Problem
Existing brake control systems for rail vehicles fail to maintain optimal braking performance under varying friction conditions, particularly in wet, snowy, or icy conditions, due to inadequate compensation for changes in friction properties between brake pads and discs.
Innovation Solution
A brake control device with a limiting device that sets maximum positive and negative control strokes independently of the control unit, allowing for non-proportional and time-dependent control strokes based on deceleration setpoints and environmental conditions, ensuring stable control and optimal braking results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a proportional controller is used to adjust braking force based on deceleration feedback, then the control system can respond to deceleration deviations, but the maximum control stroke is limited to a predetermined percentage of the requested deceleration value, which is insufficient for compensating friction variations in wet or icy conditions
Solution Approach 1:
The control system is segmented into two independent functional components: a control unit that calculates the control stroke based on deceleration feedback, and a limiting device that independently sets maximum control stroke limits. This segmentation allows the control unit to operate with high adaptability while the limiting device ensures reliability by preventing excessive control strokes, thereby resolving the contradiction between reliability and adaptability.
Solution Approach 2:
The limiting device dynamically adjusts the maximum control stroke based on operating conditions such as requested deceleration magnitude and environmental factors. Instead of using a fixed predetermined percentage, the system adapts the control stroke limits in real-time, allowing sufficient compensation for friction variations in wet or icy conditions while maintaining control stability.
2Force
If the maximum control stroke is set to a high percentage of the requested deceleration value to compensate for friction loss, then more braking force can be applied, but this may cause excessive energy input and instability in the control system
Solution Approach 1:
The limiting device applies partial action by setting maximum control stroke limits that are sufficient to compensate for friction variations but do not allow excessive control strokes. This prevents over-braking and maintains control system stability while still providing enough braking force improvement to handle reduced friction conditions.
Solution Approach 2:
The control system continuously monitors actual deceleration and compares it with the requested deceleration value. The limiting device uses this feedback to adjust the maximum control stroke dynamically, ensuring that the braking force is increased only to the extent necessary to compensate for friction loss, thereby maintaining stability while improving braking performance.
3Ease of manufacture
If a fixed predetermined percentage control stroke is used for all braking situations, then the control system is simple to implement, but it cannot adequately compensate for friction variations under different environmental conditions
Solution Approach 1:
The limiting device introduces dynamic adjustment of the maximum control stroke based on the requested deceleration value and environmental conditions. Instead of using a fixed predetermined percentage for all situations, the system adapts the control stroke limits dynamically, allowing adequate compensation for friction variations while maintaining a relatively simple implementation through programmable logic.
Data Source
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AI summary
The invention relates to a brake regulating device (2) for a rail vehicle, having an input (21) for a target deceleration value (äset), an input (22) for an actual deceleration value (atrain), and an output (23) for a deceleration control variable value, said deceleration control variable value (a0Ut) being set by a regulating unit in order to minimize a deviation between the actual deceleration value (atrain) and the target deceleration value (aset). The brake regulating device (2) is characterized in that a limiting device is provided which limits the deceleration control variable value (aout) independently of the regulating unit such that the deceleration control variable value (aout) deviates from the target deceleration value (aset) maximally by a maximum negative control stroke (14) to lower values or maximally by a maximum positive control stroke (15) to higher values. The invention additionally relates to a braking method and a brake system for a rail vehicle.