Pneumatic Brake Valve Switching for Anti-Compounding Control
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Solution Overview
Problem
Conventional electronic park brake systems rely on software solutions for anti-compounding, which fail in case of power breakdowns, necessitating a pure mechanical/pneumatic solution to prevent force overshoot by converting bistable valve behavior to relay valve behavior without additional select-high valves.
Innovation Solution
A valve arrangement with a housing, movable pistons, and a controllable throttle unit that switches between bistable and relay valve behaviors, using a first piston and a second piston to connect/disconnect control and working chambers based on control pressure, enabling pure pneumatic anti-compounding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If software solutions are used for anti-compounding in electronic park brake systems, then the control precision and reliability of brake force management is improved, but the system becomes dependent on electrical power and software functionality which may fail during power breakdowns
Solution Approach 1:
The patent replaces the electronic/software-based anti-compounding control system with a purely pneumatic/mechanical solution. The valve arrangement uses pneumatic pressure signals and mechanical valve components to detect service brake activation and automatically prevent spring brake application, eliminating dependency on electrical power and software while maintaining control precision through pneumatic pressure management.
Solution Approach 2:
The invention implements anti-compounding functionality using pneumatic principles. Control pressure from the service brake line actuates the valve mechanism, and pneumatic pressure signals are used to control the opening/closing of valve ports that regulate air flow to the spring brake chamber, thereby preventing force overshoot without requiring electrical systems.
2Reliability
If a pure pneumatic solution is implemented for anti-compounding, then the reliability during power failures is improved, but the device complexity increases due to additional valve components and pneumatic circuitry
Solution Approach 1:
The patent integrates the anti-compounding function directly into the existing park brake valve structure. The valve arrangement combines the bistable valve mechanism with anti-compounding control elements in a single integrated component, where the same valve body and piston assembly perform both parking brake control and service brake interaction functions, thereby reducing overall system complexity despite adding pneumatic capabilities.
Solution Approach 2:
The valve arrangement is designed to perform multiple functions: it operates as a bistable valve for normal park brake application and release, and simultaneously functions as an anti-compounding control valve by detecting service brake pressure and preventing spring brake activation. This multi-functionality eliminates the need for separate dedicated anti-compounding valves or control systems.
3Stability of the object's composition
If the park brake valve acts as a bistable valve, then the stability of parking brake holding is improved, but the ability to respond quickly to service brake activation for anti-compounding is reduced
Solution Approach 1:
The valve arrangement incorporates dynamic switching capability that allows it to change its operational mode based on service brake activation. During normal operation, the valve maintains bistable behavior for stable parking brake holding. When service brake pressure is detected, the valve dynamically transitions to a relay valve mode with altered internal flow paths that enable rapid response and immediate prevention of spring brake application, thus achieving both stability and speed.
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
The solution provides reliable anti-compounding without software reliance, maintaining bistability and preventing force overshoot even in power failures, by using a purely pneumatic mechanism that switches between valve behaviors.
Implementation Method 1
In response to a control pressure the second piston (120) is configured to move together with the first piston (110) to connect the pressure outlet (106) with the supply pressure inlet (102) or with the exhaust port (108)
Implementation Method 2
A throttle unit (300) is provided and adapted, depending on the control pressure, to connect the second chamber (220) with the third chamber (230) to enable the bistable valve behavior or to disconnect the second chamber (220) from the third chamber (230) to enable the relay valve behavior
Data Source
AI summary
A valve-arrangement is operable to switch between a bistable-valve (BV) behavior and a relay-valve (RV) behavior to control a parking-brake, and includes a housing with a supply-pressure-inlet (SPI), a service brake-control-inlet (SBCI) to provide a control-pressure, a pressure-outlet, and an exhaust-port, and includes a first-piston and a second-piston both movable along a same direction in the housing to define a first-chamber communicating with the SBCI, a second-chamber between the first-piston and the second-piston, and third chamber communicating with the pressure-outlet and with a controllable connection to the SPI, in which upon the control-pressure the second-piston moves with the first-piston to connect the pressure-outlet with the exhaust-port or with the SPI. The valve arrangement includes a throttle unit adapted, depending on the control-pressure, to connect the second-chamber with the third-chamber to enable the BV behavior or disconnect the second-chamber from the third-chamber to enable the RV behavior.