Method for detecting a leakage in an air spring system of a motor vehicle

An arrangement for detecting leakages in a motor vehicle air spring system including a plurality of air springs and having a level control arrangement, the level control arrangement including:

• an electronic control apparatus;
• a plurality of elevation determination sensors associated with corresponding ones of said air springs;
• a pressure sensor;
• a plurality of air spring valves corresponding to respective ones of said air springs and a compressor;
• said elevation determination sensors and said pressure sensor being connected to said control apparatus for supplying signals thereto;
• said control apparatus functioning to process said signals for controlling said air spring valves and said compressor for controlling the motor vehicle upwardly or downwardly in elevation;
• the arrangement comprising:
• said control apparatus functioning to perform the following method steps:
• at a first time point (t1), measuring the elevation-distance values (h1) and the corresponding air pressure (p1) for each air spring and storing said elevation-distance values with the time of measurement with said first time point (t1) being selected so that said control apparatus is either transferred from an active mode into a sleep mode or the corresponding elevation-distance value (h1) drops below a threshold value (hsu);
• at a second time point (t2), measuring the elevation-distance value (h2) and, if needed, the air pressure (p2) in the corresponding air springs with said second time point (t2) being so selected that either a pregiven time span (Δt) has elapsed relative to the time point (t1) and/or the corresponding elevation-distance value (h2) has dropped below a threshold value (hsu) whereby a control need is recognized;
• detecting a leakage of a particular air spring when no desired level change (hs) takes place between said first time point (t1) and said second time point (t2) and, at this particular air spring, only a pressure change was determined from said first time point (t1) to said second time point (t2) in accordance with a first condition (p1−p2)>K1 and, simultaneously, an elevation change (h2) was determined in accordance with a second condition
• {h(t1)−h(t2)}*K3/(t2−t1)>K2;
• and,
• said control apparatus including a function logic which is operatively connected to said elevation determination sensors, said pressure sensor and said air spring valves in such a manner that a leakage of the air spring system or the corresponding air spring is detected at a corner of the motor vehicle when there is a pregiven desired level (hs) between two pregiven time points (t1, t2) and when there are pressure changes in accordance with said first condition from the first time point (t1) to the second time point (t2) and when there is a simultaneous elevation level change in accordance with said second condition.