Pneumatic Brake Air Supply Flow Limiting for Parking Brake Engagement
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Solution Overview
Problem
Existing electronically controllable pneumatic brake systems in vehicles face challenges in reliably and quickly engaging the parking brake, especially when a compressor is running or in vehicles with high levels of automation, due to replenishing delivery by the compressor maintaining or increasing reservoir pressure, which prevents the parking brake from engaging.
Innovation Solution
A compressed-air supply arrangement with a delivery-rate limiting device, including a switchable valve unit, is implemented to control the flow of compressed air to the reservoir, allowing the parking brake to be engaged reliably by limiting the air flow from the compressor, even in fault conditions, using a switchable valve unit to manage the flow rate and prevent reservoir pressure increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor continues to deliver compressed air to the reservoir, then the reservoir pressure is maintained or increased, but the parking brake cannot engage reliably
Solution Approach 1:
The invention extracts the harmful effect of continuous compressed air delivery by introducing a delivery-rate limiting device that selectively restricts the air flow from the compressor to the reservoir, allowing the parking brake to engage by limiting the replenishing delivery of compressed air
Solution Approach 2:
The invention changes the parameter of compressed air delivery rate from unlimited to limited by introducing a delivery-rate limiting device with a switchable valve unit, which controls the flow rate parameter to enable reliable parking brake engagement while maintaining necessary air pressure levels
2Speed
If the compressor is running, then compressed air is continuously supplied to maintain system pressure, but this prevents quick parking brake engagement in fault conditions
Solution Approach 1:
The invention extracts the harmful continuous operation effect of the compressor by introducing a delivery-rate limiting device that can be switched to limit the compressor's delivery rate, enabling quick parking brake engagement by preventing continuous air replenishment while allowing the compressor to remain running for other system needs
3Reliability
If a delivery-rate limiting device is introduced to limit compressed air flow, then parking brake engagement is enabled, but device complexity increases
Solution Approach 1:
The switchable valve unit in the delivery-rate limiting device serves multiple functions: it limits compressed air delivery to enable parking brake engagement, maintains necessary air pressure levels for brake operation, and can be integrated into existing brake system control architecture, reducing overall system complexity despite the added component
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 engagement of the parking brake even when the compressor is running, by limiting the compressed-air delivery rate, allowing the brake to be engaged quickly and safely, even in vehicles with high levels of automation.
Implementation Method 1
at least one delivery-rate limiting device, which comprises a switchable valve unit, for limiting the compressed-air flow delivered by the compressor through the at least one compressed-air delivery line to the at least one compressed-air reservoir
Implementation Method 2
a compressor (104) for generating compressed air
Implementation Method 3
The parking brakes operate under the action of spring force, can be released by pressurization of spring brake cylinders with a parking brake pressure, and can be arrested by ventilation
Data Source
AI summary
A compressed-air supply arrangement is for supplying compressed air to an electronically controllable pneumatic brake system of a utility vehicle. An electronically controllable pneumatic brake system includes such a compressed-air supply arrangement. A corresponding utility vehicle includes such a braking system. A method is for engaging a parking brake in the event of a fault of an electronically controllable pneumatic brake system of a utility vehicle. The compressed-air supply arrangement includes a compressor, an air treatment unit, at least one compressed-air reservoir for providing a reservoir pressure, and a delivery-rate limiting device, having a switchable valve unit, for limiting the compressed-air flow delivered by the compressor to the at least one compressed-air reservoir. The switchable valve unit is switched, in the event of a fault of the brake system, via a switching signal received from an electronic brake control unit of the brake system.