Electro-Pneumatic Brake Redundancy With Alternating Axle Pressure Control
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Solution Overview
Problem
Existing redundant brake systems for autonomous vehicles are either complex and expensive or lack sufficient means to ensure vehicle stability and adequate brake force, especially when the primary brake system fails and no driver is present.
Innovation Solution
A cost-effective redundant electro-pneumatic brake control system that utilizes existing vehicle components, including an Electropneumatic Parking Brake (EPB) and a Pressure Control Valve (PCV), to independently control service and spring brakes, ensuring stable braking by alternating control between the two based on the difference in step responses of pneumatic connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a redundant brake system is designed to be simple and cost-effective, then the system complexity and cost are reduced, but the ability to ensure vehicle stability and provide adequate brake force is compromised
Solution Approach 1:
The EPB module is designed to perform multiple functions: it controls both the spring brakes (parking brake function) and the service brakes (braking function). By making the EPB multi-functional, the system eliminates the need for separate control modules for each brake type, thereby reducing system complexity and cost while maintaining the capability to provide adequate brake force and vehicle stability through a single integrated control unit
Solution Approach 2:
The patent combines the control of spring brakes and service brakes into a single pneumatic line controlled by one EPB module. This merging of control functions into a unified system reduces the number of components and simplifies the overall architecture, addressing the contradiction between simplicity and reliability by demonstrating that a consolidated control approach can maintain both vehicle stability and adequate braking performance
2Device complexity
If a redundant brake system uses a single EPB module to control both spring brakes and service brakes, then the system becomes more cost-effective and simpler, but independent control of different brake forces on different axles becomes difficult
Solution Approach 1:
The system dynamically switches between controlling spring brakes and service brakes through the single EPB module. By implementing dynamic control logic that can alternately direct the EPB's output to different brake systems based on operational requirements, the patent achieves independent control capability while maintaining a simple single-module architecture, thus resolving the contradiction between system simplicity and control versatility
Solution Approach 2:
The control system employs periodic switching between spring brake control and service brake control modes. This periodic action allows the single EPB module to sequentially serve different braking functions, effectively providing independent control over different brake forces on different axles while maintaining system simplicity through time-multiplexed operation
3Device complexity
If the EPB pressure is used to control both spring brakes and service brakes simultaneously, then the system becomes simpler, but vehicle instability and rear brake axle locking may occur
Solution Approach 1:
The patent segments the control function by implementing alternating control of spring brakes and service brakes through the single EPB module. Instead of simultaneously controlling both brake types (which would cause instability), the system divides the control timeline into separate segments where the EPB controls one brake type at a time, preventing rear brake axle locking while maintaining control system simplicity
Solution Approach 2:
The control system uses periodic switching between spring brake activation and service brake activation. This periodic action ensures that the EPB pressure is directed to spring brakes during parking/holding phases and to service brakes during driving/braking phases, preventing simultaneous application that would cause vehicle instability and rear axle locking, thereby resolving the contradiction between simplicity and stability
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 system provides reliable braking with sufficient force without vehicle instability by reusing existing components, allowing independent control of brake forces on different wheel axles, even in the absence of a driver.
Implementation Method 1
The EPB is configured to generate a controllable EPB pressure... such that the spring brakes are actuatable by the EPB pressure... such that the generated EPB pressure regulates a control pressure present at the control port
Implementation Method 2
A control pressure at the control port of the PCM is maintained when the PCV is in the closed position
Implementation Method 3
A step response of the second pneumatic connection is shorter than a step response of the first pneumatic connection... based on the difference in step response of the first and second pneumatic connections
Data Source
Figure 1~2
Figure 3A~4
Figure 5
AI summary
A redundant pneumatic brake control system for use in a vehicle (1) comprising service brakes (12) and spring brakes (11), comprising an electro-pneumatic parking brake module, EPB (13), a first pneumatic connection (15), a second pneumatic connection (16), a pressure control valve, PCV (14) and control arrangement (10). The second pneumatic connection is arranged to connect the EPB to a control port (122) of a pneumatic control module, PCM (121), such that the generated EPB pressure regulates a control pressure present at the control port. The control arrangement is configured to perform independent control of the pressure-actuated spring brakes and service brakes by alternately controlling the PCV to the open position and the closed position, based on a difference in step response of the first and second pneumatic connections, while controlling a level of the EPB pressure.