Rail Vehicle Brake Actuator Control Switching
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Solution Overview
Problem
Existing brake actuators for vehicles, particularly rail vehicles, face challenges in maintaining controllability under various operating conditions, such as when the vehicle is stationary or sliding, where controlling deceleration variables can lead to problems due to implausible coefficient of friction measurements.
Innovation Solution
The brake actuator incorporates a setpoint control device that adjusts output setpoints for contact pressure variables based on predetermined and other operating conditions, utilizing a monitoring device to generate switchover signals and automatically switch between controlling deceleration and pressure variables, with a conversion device calculating the coefficient of friction to ensure effective braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the setpoint control device regulates the deceleration variable under all operating conditions, then the braking control is simplified and consistent, but the controllability deteriorates under conditions where deceleration measurement is implausible (vehicle stationary, sliding, or implausible friction coefficients)
Solution Approach 1:
The control system dynamically switches between two control modes (deceleration variable control and contact pressure variable control) based on the current operating conditions. The monitoring device continuously evaluates parameters such as vehicle speed, friction coefficient plausibility, and wheel slip to determine which control mode is appropriate, allowing the system to adapt its control strategy to maintain reliability across all operating conditions.
Solution Approach 2:
The system changes the controlled parameter from deceleration variable to contact pressure variable when operating conditions become unfavorable for deceleration control. This parameter substitution allows the braking system to maintain effective control even when deceleration measurement becomes implausible, such as when the vehicle is stationary or sliding.
2Reliability
If the system continuously monitors and switches control modes, then the controllability under various conditions is improved, but the device complexity increases due to additional monitoring and switching mechanisms
Solution Approach 1:
The monitoring device performs multiple functions: it monitors vehicle speed, calculates friction coefficients, detects wheel slip conditions, and determines the appropriate control mode. By consolidating these monitoring and decision-making functions into a single multi-functional device, the system achieves improved controllability without proportionally increasing overall system complexity.
Solution Approach 2:
The system uses feedback from sensors measuring vehicle speed, brake pressure, and wheel rotation to continuously evaluate operating conditions. This feedback mechanism allows the monitoring device to automatically detect when deceleration control becomes implausible and trigger the appropriate control mode switch, reducing the need for complex manual intervention or additional specialized components.
3Reliability
If the setpoint control device switches to controlling the contact pressure variable, then the controllability under unfavorable conditions is improved, but the conversion from deceleration setpoint to pressure setpoint introduces calculation complexity
Solution Approach 1:
The conversion device acts as an intermediary that translates the desired deceleration setpoint into the corresponding contact pressure setpoint using the measured friction coefficient and geometric relationships. This intermediary conversion process allows the system to maintain a unified control interface (deceleration setpoint) while adapting to different control modes, reducing the need for separate control mechanisms for each mode.
Solution Approach 2:
The system uses its own measured parameters (friction coefficient, geometric relationships of the brake system) to perform the conversion calculation internally. Rather than requiring external lookup tables or complex pre-programmed conversion algorithms, the system calculates the appropriate pressure setpoint in real-time based on current operating conditions and known geometric properties of the brake actuator.
Data Source
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AI summary
The invention relates to a brake actuator (BA) for a brake system (B) of a vehicle, in particular of a rail vehicle (S), having a setpoint value control device (5) which adjusts at least one setpoint value (Sv) of a deceleration variable (Fv; Mv) to an output setpoint value (AS), having a setpoint value force conversion device (6) which converts the output setpoint value (AS) into an actual value (Ip) of a contact-pressure variable (Cp; Fp), and having brake means (9, 10, 11) which convert the actual value (Ip) of the contact-pressure variable (Cp; Fp) for braking the vehicle into an actual value (Iv) of the deceleration variable (Fv; Mv), in which brake actuator a sensor (7) determines the actual value (Ip) of the contact-pressure variable (Cp; Fp), in which brake actuator a further sensor (8) determines the actual value (Iv) of the deceleration variable (Fv; Mv), and in which brake actuator the setpoint value control device (5) is suitably designed, given predetermined operating conditions of the vehicle for controlling the deceleration variable (Fv; Mv), to set the output setpoint value (AS) such that the detected actual value (Iv) of the deceleration variable (Fv; Mv) corresponds to the at least one setpoint value (Sv) of the deceleration variable (Fv; Mv). In order to improve the ability to control the brake actuator, the setpoint value control device (5) is suitably designed, given further predetermined operating conditions of the vehicle for controlling the contact-pressure variable (Cp; Fp), to set the output setpoint value (AS) such that the detected actual value (Ip) of the contact-pressure variable (Cp; Fp) corresponds to a setpoint value (Sp) of the contact-pressure variable (Cp; Fp).