Vehicle Braking Pressure Control via Reservoir Make-up Compressor
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Solution Overview
Problem
Heavy vehicle braking systems face pressure drops in brake chambers when a valve is in the apply state, affecting braking torque availability across the circuit.
Innovation Solution
A controller electronically manages switching valves to maintain braking pressures at wheels by adjusting valve states (apply, hold, release) based on criteria such as pressure differences and braking demands, ensuring consistent pressure distribution across brake chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If a valve is actuated to apply state to increase volume for compressed air storage, then the volume available for compressed air increases, but the pressure in the reservoir drops
Solution Approach 1:
The system performs preliminary action by activating a make-up compressor to replenish reservoir pressure before it drops to critical levels. The controller monitors pressure and proactively activates the compressor to maintain pressure within the desired range, preventing the harmful effect of pressure drop on braking performance.
Solution Approach 2:
The system implements feedback control by continuously monitoring reservoir pressure through sensors and using this information to control valve actuation and compressor operation. The controller adjusts the system based on real-time pressure feedback, activating the make-up compressor when pressure drops below a threshold and deactivating it when pressure is restored, thereby maintaining stable pressure despite volume changes during braking operations.
2Speed
If compressed air is distributed to multiple brake chambers simultaneously, then braking response at all wheels improves, but pressure drop in the reservoir increases
Solution Approach 1:
The system performs preliminary action by pre-charging the reservoir to a higher pressure level before simultaneous brake application, and by activating the make-up compressor in advance when pressure trends indicate upcoming demand. This ensures that when multiple brakes are applied simultaneously, sufficient pressure is available to maintain rapid response without excessive pressure drop.
Solution Approach 2:
The make-up compressor operates continuously or in repeated short cycles to maintain reservoir pressure within the optimal range during periods of high brake demand. Rather than allowing pressure to drop and then recovering, the system maintains continuous pressure supplementation, ensuring that simultaneous brake applications at multiple wheels can occur without compromising response speed or pressure availability.
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 maintains higher braking pressures and reduces pressure drops, enhancing braking torque consistency and vehicle control during ABS events.
Implementation Method 1
Heavy vehicle braking systems commonly rely on compressed air for operating a vehicle braking system. Compressed air is produced by a compressor and stored in at least one reservoir.
Implementation Method 2
If an increased volume is available for the same amount of compressed air, the pressure of the compressed air in the increased volume drops.
Data Source
AI summary
A controller controls respective braking pressures at wheels on a vehicle. The controller includes a processor electrically communicating with each of a plurality of switching valves, which controls braking pressures at respective wheels. The processor, during a braking event having a brake demand above a braking demand threshold, controls each of the switching valves to maintain braking pressures at the respective wheels based on at least one additional criteria.