Pressure measuring device and corresponding method
First Claim
1. 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 (V1) 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 (V2) 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 (V1) during the first stroke, and equal to the second voltage (V2) 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.
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Accused Products
Abstract
Device for measuring cylinder pressure of an internal combustion engine includes a pressure sensor that includes a piezoelectric element associated with a capacitive element, and an output generating a first voltage representative of the cylinder pressure. A filtering module of the device filters parasitic low-frequency voltages and generates a second voltage free of these parasitic voltages. A control module delivers a control signal that is dependent on a switching parameter correlated with a stroke. A switching module, in response to the control signal, disconnects the input of the filtering module from the output of the pressure sensor during the first stroke and connects the input of the filtering module to the output of the pressure sensor during the second stroke. The first stroke corresponds to a compression stroke or to a combustion-expansion stroke, and the second stroke corresponds to an intake stroke or to an exhaust stroke.
16 Citations
14 Claims
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1. 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:
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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 (V1) 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 (V2) 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 (V1) during the first stroke, and equal to the second voltage (V2) 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method 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 method comprising:
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generating a first voltage (V1) representative of a pressure (F) applied to a piezoelectric element associated with a capacitive element; delivering a control signal (Scom) that is dependent on a switching parameter correlated with an engine stroke, among the first and second strokes, in which the engine is operating; when the switching parameter is correlated with the first stroke, generating an output signal (Vout) equal to the first voltage (V1), in response to the control signal (Scom); and when the switching parameter is correlated with the second stroke, filtering the parasitic low-frequency voltages present in the first voltage (V1), and generating an output signal (Vout) equal to a second voltage (V2) representative of the first voltage (V1) free of these low-frequency voltages, in response to the control signal (Scom), the first stroke corresponding to a compression stroke or to a combustion-expansion stroke, and the second stroke corresponding to an intake stroke or to an exhaust stroke.
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Specification