Rail Vehicle Brake Unit Load-Corrected Emergency Braking
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Solution Overview
Problem
Existing brake units for rail vehicles face challenges in providing a safe emergency braking force that is not affected by variations in vehicle load, leading to potential over-braking or under-braking due to incorrect emergency braking force application.
Innovation Solution
The brake unit incorporates a load-corrected passive emergency braking system, utilizing a pressure transmitter and load correction means adjusted by electrical output signals from a fallback device to ensure a safe braking state, with an electro-hydraulic setpoint-force conversion device that includes a pressure sensor and control means to set and adjust preload pressure accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed emergency braking force is provided without load correction, then the braking system is simple to operate, but the braking performance deteriorates under varying load conditions leading to over-braking or under-braking
Solution Approach 1:
The brake system pre-charges a pressure transmitter (accumulator) with hydraulic fluid under normal operating conditions. In the event of a fault, this pre-stored pressure is immediately available to provide load-corrected emergency braking force without requiring complex real-time sensing or calculation during the emergency event itself.
Solution Approach 2:
A pressure transmitter (accumulator) is introduced as an intermediary element that stores hydraulic pressure and automatically provides load-corrected braking force during emergencies. This mediator decouples the complexity of load correction from the emergency braking activation, allowing simple fault-triggered operation while maintaining reliable performance.
2Reliability
If load correction is implemented for emergency braking, then the braking performance is improved across varying loads, but the device complexity increases due to additional sensors and control means
Solution Approach 1:
The system performs load correction准备工作 in advance by continuously maintaining the pressure transmitter charged with hydraulic fluid at normal operating pressure. This preliminary action ensures that when emergency braking is triggered, the load-corrected braking force is immediately available without requiring complex real-time computation or sensor processing during the critical emergency event.
Solution Approach 2:
The pressure transmitter automatically provides load-corrected braking force based on its pre-charged pressure level, which inherently reflects the vehicle's load condition. This self-service mechanism eliminates the need for complex electronic control algorithms or additional sensors during emergency operation, as the hydraulic system itself carries the load correction information.
3Reliability
If the emergency braking force is increased to ensure adequate braking under all loads, then braking safety is improved, but the risk of over-braking and wheel flat spots increases
Solution Approach 1:
The system changes the pressure parameter of the hydraulic fluid in the pressure transmitter based on the vehicle's load condition. During normal operation, the pressure is adjusted to reflect the current load, and this load-dependent pressure is then used to provide appropriately scaled emergency braking force, preventing both under-braking and over-braking.
Solution Approach 2:
The pressure transmitter is pre-charged to a pressure level that corresponds to the vehicle's load condition before any emergency occurs. This preliminary pressure adjustment ensures that when emergency braking is activated, the braking force is already correctly scaled to the load, eliminating the need for aggressive force increases that would cause wheel flat spots.
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 ensures a reliable and load-corrected passive emergency braking force, reducing the risk of flat spots and excessively long braking distances, while allowing for simple and effective adjustment and implementation in various brake unit types (electro-hydraulic, electro-pneumatic, or electro-mechanical).
Implementation Method 1
a pressure transmitter and load correction means, and the load correction means are suitably designed to set a preload pressure of the pressure transmitter
Implementation Method 2
an electro-hydraulic setpoint-force conversion device that includes a pressure sensor and control means to set and adjust preload pressure accordingly
Implementation Method 3
a brake cylinder with brake pistons connected to the container via a hydraulic line system
Implementation Method 4
first braking means actuated by the brake actuator... frictional engagement with the second braking means
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a brake unit (9; 109; 209) for a vehicle, in particular a rail vehicle (1), which can be mounted on running gear (3) of the vehicle and has means (30, 31, 132; 232) for making available a regulated braking force (FB) and a passive emergency braking force (FN). In order to permit safe braking by means of the emergency braking force which is made available, even in the case of a fault during the provision of the regulated braking force, there is provision that the means (30, 31, 132; 232) are of suitable design to make available the passive emergency braking force (FN) in a load-corrected fashion and have a pressure signal transmitter (50) and a load correction means (45, 46) for correcting the load of the passive emergency braking force (FN), wherein the load correcting means (45, 56) are of suitable design for setting a preload pressure (pN) of the pressure signal transmitter (50) as a function of electrical output signals (AS4, AS5) of a fallback device (37) to a load-corrected setpoint value (S.pN). The invention also relates to a vehicle (1) with such a brake unit (9; 109; 209).