Pilot Valve Redundancy for Pneumatic Brake Control
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Solution Overview
Problem
Existing pneumatic brake systems in commercial vehicles face challenges in maintaining driving stability during automated braking procedures, especially in cases of electrical malfunction where ABS control valves may not be reliably actuated, leading to potential wheel lock-up and impaired braking performance.
Innovation Solution
A method is introduced where a pilot valve is electronically actuated with a redundancy signal to produce an intermittent braking pressure, oscillating between high and low levels, ensuring that wheels that tend to lock can rotate again by periodically reducing the service brake braking pressure below a limit pressure, thus maintaining driving stability even in the absence of electrical actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic actuation is used for axle modulators, then braking control precision is improved, but system reliability deteriorates due to electrical malfunction risk
Solution Approach 1:
The patent changes the actuation parameter from electrical to pneumatic in the event of electrical malfunction. The redundancy control unit detects electrical failures and automatically switches the axle modulator actuation from electronic control to pneumatic control via the pilot valve, maintaining braking functionality despite electrical system failures.
Solution Approach 2:
The pilot valve serves as an intermediary component that enables alternative actuation paths. When electrical actuation fails, the pilot valve mediates between the compressed air reservoir and the axle modulator, allowing pneumatic actuation to take over and maintain system reliability.
2Productivity
If continuous braking pressure is applied, then stopping efficiency is improved, but wheel lock-up risk increases leading to loss of driving stability
Solution Approach 1:
The patent implements periodic action through alternating the pilot valve between first and second switch positions. This creates periodic modulation of braking pressure applied to the wheels, preventing continuous high pressure that would cause lock-up while maintaining sufficient stopping efficiency through repeated pressure application cycles.
Solution Approach 2:
The system dynamically adjusts braking pressure by transitioning from static continuous pressure to dynamic alternating pressure. The pilot valve's switching between positions creates time-varying pressure profiles that adapt to wheel slip conditions, maintaining driving stability while preserving stopping capability.
3Reliability
If additional components are added to ensure smooth braking, then braking performance is improved, but device complexity increases
Solution Approach 1:
The pilot valve is designed with multi-functionality, serving both normal braking operations and redundancy functions. By making the pilot valve universal, the patent avoids adding separate dedicated components for redundancy, thereby improving braking performance and reliability without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the redundancy control functionality with the existing pilot valve structure. The redundancy control unit integrates with the pilot valve's switching mechanism, combining multiple functions (normal actuation, redundancy activation, pressure modulation) into a unified system rather than adding separate independent components.
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 approach allows for safe and reliable electronically controlled redundant braking, maintaining vehicle stability and preventing wheel lock-up by using a simple pilot valve and redundancy control unit, reducing the need for additional components that ensure smooth braking or low wear, and is effective in typical driving situations.
Implementation Method 1
The pilot valve outputs, as a pilot pressure, a low pressure level in the first switch position and a high pressure level in the second switch position
Implementation Method 2
the respective axle modulator generates the corresponding service brake braking pressure for the service brakes by means of increasing the quantity of air
Implementation Method 3
a service brake braking pressure that recurrently drops at least for a limit time below a limit pressure so as to initiate an intermittent braking procedure
Data Source
AI summary
A method for electronically controlling a pneumatic brake system in a vehicle includes determining that a failure or a defect has occurred in electronic actuation of wheel brakes of the pneumatic brake system, and electronically actuating a pilot valve via a redundancy signal in response to determining that the failure or the defect in the electronic actuation has occurred so as to actuate the wheel brakes in a redundant electropneumatic manner. The redundancy signal is specified in such a manner that the pilot valve alternately turns for a pulse time into a second switch position and for a pause time into a first switch position. The pilot valve outputs, as a pilot pressure, a low pressure level in the first switch position and a high pressure level in the second switch position. The wheel brakes are actuated using a service brake braking pressure that is dependent upon the pilot pressure.