Multi-Circuit Protection Valve for Vehicle Air Brake Systems
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Solution Overview
Problem
Existing pneumatic brake systems in commercial vehicles face challenges in ensuring that the service brake circuits are filled with sufficient pressure before the parking brake circuit, to guarantee the parking brake remains engaged until sufficient braking force is applied, as per legal requirements.
Innovation Solution
A multi-circuit protection valve design with an overflow valve having three active surfaces, where the service brake pressure from the less filled service brake circuit counteracts a closing force to open or keep the overflow valve open, ensuring the service brake circuits are filled before the parking brake circuit, and incorporating check valves and control valves to prioritize filling of the service brake circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the parking brake circuit is supplied in parallel with service brake circuits, then the filling time is reduced, but the legal requirement that service brake must be filled before parking brake cannot be ensured
Solution Approach 1:
The overflow valve acts as an intermediary component between the service brake circuits and the parking brake circuit. It uses pressure differential forces on its piston surfaces to control the timing of compressed air supply, ensuring that the parking brake circuit only receives air after both service brake circuits have been filled to sufficient pressure, thus maintaining legal compliance while enabling parallel supply architecture
Solution Approach 2:
The invention changes the pressure parameter threshold for opening the overflow valve. By designing the piston with specific surface areas (A1, A2, A3) that create a pressure differential requirement, the system ensures that only when both service brake circuits reach sufficient pressure (changing the pressure parameter) will the overflow valve open and allow the parking brake circuit to fill, thereby enforcing the required filling sequence
2Device complexity
If overflow valves are designed with traditional two-surface pistons, then the structure is simple, but the filling sequence of both service brake circuits before parking brake cannot be enforced
Solution Approach 1:
The overflow valve piston is segmented into multiple effective surfaces (A1, A2, A3) that respond to different pressure sources. The first surface responds to parking brake pressure, the second to one service brake circuit, and the third to the other service brake circuit. This segmentation allows the valve to independently monitor both service brake circuits and enforce that both must be filled before allowing parking brake supply
Solution Approach 2:
The overflow valve performs multiple functions simultaneously: it protects against overpressure in the parking brake circuit, enforces the filling sequence requirement, and monitors the pressure status of both service brake circuits. This multi-functionality is achieved through the multi-surface piston design that integrates sequence control and pressure protection in a single component
3Reliability
If check valves are added to prioritize service brake circuit filling, then the filling sequence is controlled, but the device complexity increases
Solution Approach 1:
The invention merges the sequence control function and the overflow protection function into a single overflow valve assembly. The check valves are integrated with the overflow valve piston mechanism, allowing the piston to respond to pressure from both service brake circuits through the check valves while simultaneously providing overpressure protection. This merging reduces overall system complexity compared to having separate sequence control valves and overflow valves
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
Ensures that both service brake circuits are filled before the parking brake circuit, meeting the legal requirement of maintaining the parking brake engaged until sufficient braking force is applied, and maintains operational integrity even with defects in one service brake circuit.
Implementation Method 1
the forces generated via the three effective surfaces counteract a closing force in order to open or open the overflow valve
Data Source
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AI summary
The invention relates to a multi-circuit protection valve (10) for a compressed-air supply device of a vehicle, having a first port (12) for a service brake, wherein the first port (12) comprises two mutually separate service brake circuit ports (26, 28) for a first service brake circuit (58) and a second service brake circuit (60), and wherein the two service brake circuit ports (26, 28) are protected by a first and a second service brake circuit overflow valve (30, 32), and having a second port (14) for a parking brake, which second port is protected by an overflow valve (16), wherein one of the two service brake circuits (58, 60) can be filled preferentially, and wherein the overflow valve (16) has two active surfaces (18, 20) which can be acted on with a valve inlet pressure and a valve outlet pressure respectively. It is provided according to the invention that the overflow valve (16) has a third active surface (22) which can be acted on with the service brake pressure from the non-preferentially filled service brake circuit (60; 58) of the service brake, and that forces (18', 20', 22') generated by means of the three active surfaces (22, 18, 20) counteract a closing force (24) in order to open or hold open the overflow valve (16). The invention also relates to a method for operating a multi-circuit protection valve (10) for a compressed-air supply device of a vehicle.