Electro-pneumatic Parking Brake Bi-stability via Segmented Magnet Valves
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Solution Overview
Problem
Existing electro-pneumatic parking brake systems for commercial vehicles face challenges in achieving easy and accurate control while ensuring bi-stability and proportional brake force control, particularly in maintaining the safe state during failures and trailer service brake control, often requiring complex and costly solutions.
Innovation Solution
A robust electro-pneumatic parking brake arrangement using two 3 by 2 magnet valves with specific fluid connections for pressure control, including connections to the parking brake pressure supply and ambient pressure, allows for precise control of the parking brake pressure and trailer service brake control, incorporating additional sensors for enhanced monitoring and control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expensive and complex solutions are used to ensure bi-stability and proportional brake force control, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The control system is segmented into two independent 3 by 2 magnet valves (first magnet valve for supply pressure control, second magnet valve for exhaust control) that work in coordination. This segmentation allows each valve to handle specific control functions independently, simplifying the overall control logic while maintaining reliable bi-stable operation through distributed control architecture.
Solution Approach 2:
The invention uses pneumatic pressure control through magnet-actuated valves to achieve bi-stability and proportional brake force control. By utilizing pneumatic signals and pressure differentials rather than complex electronic control systems, the solution achieves reliable control with simpler components, directly applying pneumatic principles to resolve the contradiction between reliability and complexity.
2Reliability
If minimal pressure in drive state is limited above zero to ensure safe state, then reliability is improved, but manufacturing precision and control accuracy requirements increase
Solution Approach 1:
A relay valve is introduced as an intermediary component between the magnet valves and the spring brake chamber. The relay valve receives control signals from the magnet valves and amplifies them to produce the necessary pressure changes in the brake chamber, thereby reducing the precision requirements for the magnet valves while ensuring reliable safe state maintenance through the relay valve's inherent pressure control characteristics.
Solution Approach 2:
The system maintains a minimal positive pressure above zero in the drive state as a pre-established safety margin. This cushioning pressure ensures that even with variations in component characteristics, the system remains in the desired safe state without requiring extremely high manufacturing precision, as the pressure buffer provides tolerance for component variations.
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 provides a cost-effective and accurate control mechanism for the parking brake system, ensuring the safe state and proportional brake force control, even during failures and trailer service brake operations, without overloading the brake mechanism.
Implementation Method 1
two 3 by 2 magnet valves with specific fluid connections for pressure control
Implementation Method 2
a 3 by 2 pneumatically controlled valve having a fluid connection from an output port to a control port for defining the valve switching position by the output pressure
Implementation Method 3
providing control pressure for a relay valve setting up a parking brake pressure in a spring brake chamber
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An electro-pneumatic parking brake arrangement, comprising a 3 by 2 pneumatically controlled valve (3) having a fluid connection from an output port (3.3) to a control port (3.4) for defining the valve switching position by the output pressure and providing control pressure for a relay valve (5) setting up a parking brake pressure in a springbrake chamber of a brake cylinder (8) through an output port (B) of the relay valve (5), wherein a variable pressure level which is feeding an inlet port (3.1) of the pneumatically controlled valve (3) is provided by two 3 by 2 magnet valves (1, 2), further comprising: - a fluid connection to the parking brake pressure supply input (A) provided through the parking brake check valve (7) by inlet port (1.2) of load magnet valve (1), and - a fluid connection to the ambient pressure provided by exhaust port (2.2) of the exhaust magnet valve (2), and - a fluid connection from an outlet port (1.3) of load magnet valve (1) to an inlet port (2.1) of the exhaust valve (2) and the inlet port (3.1) of the pneumatically controlled valve (3), and - a fluid connection from an outlet port (2.3) of the exhaust valve (2) to an inlet port (1.1) of the load valve (1).