Patent ID: 8297114

Claim:
A device for measuring the cylinder pressure of an internal combustion engine that operates with a plurality of successive cycles, each cycle being broken down into at least first and second strokes, the measuring device comprising: at least one pressure sensor ( 1 ) comprising at least one piezoelectric element associated with a capacitive element, and an output ( 10 ) generating a first voltage (V 1 ) representative of a pressure (F) applied to the piezoelectric element; a filtering module ( 2 ) comprising at least one input ( 20 ) and one output ( 21 ), capable of filtering parasitic low-frequency voltages present at its input ( 20 ), and of generating on its output ( 21 ) a second voltage (V 2 ) free of these parasitic low-frequency voltages; a control module ( 3 ) capable of delivering a control signal (Scom) that is dependent on a switching parameter correlated with a stroke, among the first and second strokes, in which the engine is operating; a switching module ( 4 ), in response to the control signal (Scom), capable of disconnecting the input ( 20 ) of the filtering module ( 2 ) from the output ( 10 ) of the pressure sensor ( 1 ) during the first stroke, and of connecting the input ( 20 ) of the filtering module ( 2 ) to the output ( 10 ) of the pressure sensor ( 1 ) during the second stroke; and an output ( 5 ) generating an output voltage (Vout) equal to the first voltage (V 1 ) during the first stroke, and equal to the second voltage (V 2 ) during the second stroke, wherein the first stroke corresponds to a compression stroke or to a combustion-expansion stroke, and in which the second stroke corresponds to an intake stroke or to an exhaust stroke.