Series Parking Brake Valve Assembly for Fault-Tolerant Venting
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Solution Overview
Problem
Existing pneumatic braking systems for utility vehicles lack the ability to independently ventilate and vent spring-loaded brake cylinders across different operational and redundancy levels, limiting the system's functionality and operational readiness in case of faults.
Innovation Solution
A parking brake valve assembly with two independent parking brake valve units, where the first unit is actuated by a first parking brake signal and the second unit by a second independent signal, allowing the parking brake working connection to be ventilated or vented regardless of the switching position of the other unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single parking brake valve unit is used, then the device complexity is reduced, but the reliability decreases because the system cannot independently ventilate and vent brake cylinders across different operational levels
Solution Approach 1:
The parking brake valve assembly is divided into two independent parking brake valve units (first and second units), each capable of being actuated by independent signals. This segmentation allows the system to independently control and switch between different operational levels (service brake and parking brake), ensuring that if one unit fails, the other can still maintain operational readiness. Each valve unit can independently ventilate or vent the brake cylinders, providing redundancy and enhanced reliability.
2Reliability
If two independent parking brake valve units are used, then the reliability and operational readiness are improved, but the device complexity increases
Solution Approach 1:
The system is segmented into two independent valve units that can operate autonomously. Each unit has its own actuation signal path, allowing them to function independently. This segmentation provides fault tolerance because a failure in one unit does not compromise the other, maintaining system reliability while managing complexity through modular independence.
Solution Approach 2:
Both parking brake valve units are designed with identical functionality, each capable of controlling the service brake and parking brake operations. This multi-functionality allows either unit to take over if the other fails, providing universal coverage for all operational scenarios and enhancing fault tolerance without requiring different types of components.
3Adaptability or versatility
If the valve units are connected in parallel, then the operational independence is improved, but the loss of substance increases due to potential pressure leakage paths
Solution Approach 1:
The two parking brake valve units are connected in series within the pneumatic circuit, meaning the output of one valve unit feeds into the input of the next. This series pneumatic connection ensures that compressed air flows through both valves sequentially, eliminating parallel leakage paths while maintaining independent operational control. The series configuration guarantees that both valves must be in the appropriate position for air to reach the brake cylinders, preventing unwanted pressure loss.
Data Source
AI summary
A parking brake valve assembly for a pneumatic braking system of a vehicle includes a first parking brake valve unit and a second parking brake valve unit. The first parking brake valve unit is actuated by a first parking brake signal and is switchable from a first to a second switching position, and the second parking brake valve unit is actuated by a second parking brake signal and is switchable from a first to a second switching position. The first and second parking brake signal are mutually independent. The first and second parking brake valve unit are pneumatically connected in series between a parking brake supply connection and a parking brake working connection such that the parking brake working connection can be both ventilated and vented independently of the switching position of one of the parking brake valve assemblies by switching the other parking brake valve assembly.