Patent ID: 6931930

Claim:
A method for determining pressure in an interior space of an air spring of a motor vehicle, the air spring including a cover plate and a roll-off piston, the method comprising the steps of: providing an ultrasonic pulse/echo measuring arrangement including: an ultrasonic transducer fixedly mounted on said cover plate; a reference reflector fixedly mounted in said air spring; and, a transmitter/receiver evaluation circuit; providing said ultrasonic transducer with a λ/4 adaptation layer having an impedance unequal to the geometric mean of the impedance of the ultrasonic transducer and the impedance of the ambient air of said interior space of said air spring so as to define a mismatch; and, driving said ultrasonic transducer to generate oscillations reflected from said reference reflector and to form a reference signal having a running time and an amplitude; and, evaluating said running time and said amplitude of said reference signal in said transmitter/receiver evaluation circuit to determine said pressure in said interior space of said air spring.