Air Spring Level Control Pre-filling to Prevent Sagging
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Solution Overview
Problem
Modern motor vehicle level control systems experience sagging during air spring filling due to initial compressed air escape, which is exacerbated by the presence of air dryers, and non-return valves hinder air delivery, delaying vehicle body raising.
Innovation Solution
A method involving a switchable directional control valve and a master line that is filled with compressed air until a predetermined threshold pressure is reached before filling the air spring, eliminating the need for a non-return valve and minimizing sagging by ensuring minimal air escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-return valve is placed between the air springs and the air drier or compressed air source to prevent compressed air from escaping, then sagging of the vehicle body is prevented, but the non-return valve acts like a resistor which hinders air delivery and delays raising of the vehicle body
Solution Approach 1:
The control system pre-fills the master line with compressed air before opening the directional control valve to the air spring. This preliminary action ensures that when the valve switches, compressed air is already available in the master line, eliminating the need for a non-return valve and avoiding the resistance it would create while still preventing air escape that causes sagging.
2Reliability
If the master line is filled with compressed air before filling the air spring to prevent sagging, then air escape is minimized, but the filling process is delayed due to the additional pre-filling step
Solution Approach 1:
The system performs preliminary filling of the master line with compressed air before the actual air spring filling operation. This pre-action is controlled by a timer or pressure sensor, ensuring the master line is ready with sufficient compressed air to immediately fill the air spring when the directional valve switches, preventing sagging while minimizing delay.
Solution Approach 2:
The control system uses pressure sensors to monitor the compressed air pressure in the master line and adjusts the pre-filling duration based on the measured pressure. This feedback mechanism ensures the master line is filled to the optimal pressure level, preventing both sagging and excessive delay in the filling process.
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 prevents significant vehicle body sagging during air spring filling, reduces compressor runtime and temperature increase, and allows for precise pressure control, minimizing filling delays and eliminating the need for a non-return valve.
Implementation Method 1
The master line is filled with compressed air until an air pressure in the master line is at least equal to a predetermined threshold value, before filling the at least one air spring
Implementation Method 2
a switchable directional control valve associated with the air spring... connecting the compressed air source to the switchable directional control valve with a master line
Data Source
AI summary
A method for controlling or regulating a level control system for a motor vehicle including a compressed air source, at least one air spring, a switchable directional control valve associated with the air spring and a master line connecting the compressed air source to the switchable directional control valve. The switchable directional control valve blocking the master line in a normal state thereof and connecting the master line through for filling the air spring in a switching state thereof. The master line is filled with compressed air before filling the air spring until the air pressure in the master line is at least equally as high as a predetermined threshold value, and only thereafter is the switchable directional control valve transferred into the switching state for filling the air spring. A level control system for a motor vehicle is also provided.