Peak combustion pressure timing detector for internal combustion engine

Patent · Tue Jul 22 00:00:00 EDT 1986

OSTI ID:5476317

Fattic, G T; Dennis, D S; Ricketts, W J

This patent describes an apparatus for sensing the timing of peak combustion pressure in the combustion chamber of an internal combustion engine comprising, in combination: pressure sensing apparatus including a piezoelectric element adapted for flexure in response to variations in combustion chamber pressure, the piezoelectric element having a capacitance varying with the flexure; a first resistance connected electrically in parallel with the capacitance of the piezoelectric element with grounded and ungrounded junctions; constant current generating means adapted to supply a constant current to the ungrounded junction, the constant current being effective, when the capacitance remains constant, to establish a predetermined voltage across the first resistance and thereby across the capacitance; a second resistance; a referenced voltage source effective to provide the predetermined voltage; an operational amplifier having an output connected through the second resistance to the ungrounded junction and through a third resistance to the grounded junction, an inverting input connected to the output through a feedback resistance and a non-inverting input connected to the reference voltage source, the operational amplifier thus comprising a variable current source and sink effective to maintain the predetermined voltage on the capacitance; and output circuit means connected to the output of the operational amplifier, the voltage theron corresponding to the derivative of the pressure sensed by the piezoelectric element and thus indicating the timing of peak combustion pressure as it passes through the predetermined voltage.

• Assignee: General Motors Corp., Detroit, MI
• Patent Number(s): US 4601197
• OSTI ID: 5476317
• Resource Relation: Patent File Date: Filed date 12 Jul 1985
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
COMBUSTION CHAMBERS
PRESSURE GAGES
INTERNAL COMBUSTION ENGINES
AMPLIFIERS
CAPACITANCE
COMBUSTION KINETICS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRIC GROUNDS
ELECTRIC POTENTIAL
ELECTRONIC CIRCUITS
INVERTERS
PIEZOELECTRICITY
TEMPERATURE MEASUREMENT
CHEMICAL REACTION KINETICS
CURRENTS
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
ELECTRICITY
ELECTRONIC EQUIPMENT
ENGINES
EQUIPMENT
HEAT ENGINES
KINETICS
MEASURING INSTRUMENTS
PHYSICAL PROPERTIES
REACTION KINETICS
330100* - Internal Combustion Engines