Bistable Valve Direct Air Supply for Parking Brake Reliability
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Solution Overview
Problem
Current electric parking brakes with bistable valves only allow for staged braking above a certain minimum pressure, leading to potential safety issues during power failures, as they automatically engage below this pressure, risking unintended braking or failure.
Innovation Solution
An electric parking brake system with a bistable valve connected directly to the compressed air supply, independent of the valve arrangement, and a pneumatically controlled valve that inverts pressure, ensuring reliable operation even in power failures, and includes a trailer test function to check brake effectiveness before parking on inclines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bistable valve is connected to the valve arrangement and dependent on its switching state, then the valve arrangement can control compressed air distribution, but the braking system fails during power outages when pressure drops below minimum threshold
Solution Approach 1:
The bistable valve is extracted from the dependent connection to the valve arrangement and reconnected directly to the compressed air supply. This separation allows the valve to maintain its switching positions independently of the valve arrangement's operational state, ensuring brake functionality persists even when the valve arrangement fails during power outages.
Solution Approach 2:
The bistable valve is pre-configured with direct compressed air supply connection that maintains sufficient pressure in the brake circuit regardless of the valve arrangement's state. This preliminary pressure maintenance ensures that the parking brake remains functional and can be activated even during power outages before any pressure depletion occurs.
2Reliability
If the bistable valve is supplied with compressed air from the compressed air supply independently of the valve arrangement, then the parking brake remains functional during power outages, but the compressed air consumption increases
Solution Approach 1:
The system applies partial action by providing compressed air supply only to the bistable valve's necessary ports for maintaining its switching positions, rather than supplying all components. This selective supply ensures adequate pressure for brake functionality during power outages while minimizing unnecessary compressed air consumption.
3Stability of the object's composition
If the minimum pressure at compressed air outlets is approximately 1 bar above ambient pressure, then the bistable valve maintains switching behavior, but the parking brake automatically engages and staged braking is limited
Solution Approach 1:
The system changes the pressure parameter by providing direct compressed air supply to the bistable valve, maintaining pressure well above the 1 bar threshold even during power outages. This parameter change allows the valve to maintain its switching behavior while enabling broader adaptability for staged braking control through the pneumatic control connection.
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 reliable brake operation and trailer safety by maintaining brake effectiveness during power failures and allowing a trailer test function, preventing jackknifing and ensuring stable parking on inclines.
Implementation Method 1
a bistable valve (24) for controlling a distribution of compressed air from a compressed air supply (50) to compressed air consumer circuits (60)
Implementation Method 2
a relay valve (29) for the spring-applied parking brake having a control connection for control with compressed air applied on the outlet side of the bistable valve (24)
Data Source
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AI summary
The invention relates to an electronic or electric parking brake, in particular for a commercial vehicle, comprising at least two compressed air outlets, an electrically controllable valve arrangement for controlling a compressed air distribution to the compressed air outlets comprising a bistable valve, a compressed air inlet which can be connected to a compressed air supply for supplying the valve arrangement and the compressed air outlets with compressed air from a compressor and/or a compressed air reservoir, wherein the bistable valve is supplied on the inlet side with compressed air from the compressed air supply independently of the switching state of the valve arrangement, which has a pressure provided by the compressor and/or the compressed air reservoir.The invention builds upon the generic electric or electronic parking brake in that the valve arrangement includes a pneumatically controlled valve for inverting a supply pressure for a trailer control module, and wherein the pneumatically controlled valve is controlled by the bistable valve. This increases the reliability of the electric parking brake.