Patent ID: 6745614
Filing Date: 2004-06-08
Classification: B60G,G01M

Abstract:
A method 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 method comprising the steps of: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 (&Dgr;t) 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; and, 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 (p1âˆ’p2)>K1 and, simultaneously, an elevation change (h2) was determined in accordance with a second condition {h(t1)âˆ’h(t2)}*K3/(t2âˆ’t1)>K2.