Method of detecting low compression pressure responsive to crankshaft acceleration measurement and apparatus therefor

A method of compression pressure determination in a combustion chamber of a cylinder in a running engine, said method comprising the steps of:

• measuring acceleration of a crankshaft of said running engine, said measurement centered proximate a maximum rate of compression of said cylinder, and providing a first acceleration variable responsive thereto;
• measuring an intake manifold pressure of said running engine, and providing an intake manifold pressure variable responsive thereto;
• and
• providing a compression pressure variable indicative of a compression pressure in the combustion chamber of the cylinder in said running engine by dividing the first acceleration variable by the measured intake manifold pressure variable.

A method of compression pressure determination in a combustion chamber of a cylinder in a running engine, said method comprising the steps of:

• measuring an intake manifold pressure of said running engine associated with a pressure of air ingested into the combustion chamber of the cylinder, and providing an intake manifold pressure variable responsive thereto;
• measuring a first acceleration of a crankshaft of said running engine, coincident with a compression cycle of the cylinder and providing a first acceleration variable responsive thereto;
• measuring a second acceleration of the crankshaft of said running engine coincident proximate the cylinder's top-dead-center position, and providing a second acceleration variable responsive thereto;
• and
• providing a compression pressure variable having a magnitude indicative of a compression pressure in said combustion chamber of the cylinder determined dependent on an amplitude of the first acceleration variable, and an amplitude of the second acceleration variable, and the measured intake manifold pressure variable.

A method of compression pressure determination in a combustion chamber of a cylinder in a running engine, said method comprising the steps of:

• measuring an intake manifold pressure of said running engine associated with a pressure of air ingested into the combustion chamber of the cylinder, and providing an intake manifold pressure variable responsive thereto;
• measuring a first acceleration of a crankshaft of said running engine, coincident with a compression cycle of the cylinder and providing a first acceleration variable responsive thereto, wherein the first acceleration measurement is executed proximate .+-.10.degree. of the cylinder's maximum compression;
• measuring a second acceleration of the crankshaft of said running engine coincident proximate the cylinder's top-dead-center position, and providing a second acceleration variable responsive thereto wherein the second acceleration measurement is executed proximate .+-.10.degree. of the cylinder's top-dead-center position;
• and
• providing a compression pressure variable indicative of a compression pressure in said combustion chamber of the cylinder as a function of the first acceleration variable, the second acceleration variable, and the measured intake manifold pressure variable.

A method of compression pressure determination in a multi-cylinder reciprocating engine, said method comprising the steps of:

• measuring an intake manifold pressure for each of a plurality of cylinders in said multi-cylinder reciprocating engine, and providing a plurality of intake manifold pressure variables responsive thereto for each of the plurality of cylinders;
• measuring a first acceleration of a crankshaft for each of the plurality of cylinders in said multi-cylinder reciprocating engine, and providing a plurality of first acceleration variables responsive thereto;
• measuring, later in time, a second acceleration of the crankshaft for each of the plurality of cylinders in said reciprocating engine, and providing a plurality of second acceleration variables responsive thereto;
• and
• subtracting each of the plurality of first acceleration variables from each of the plurality of second acceleration variables and dividing each of the plurality of differences by each of the plurality of intake manifold pressure variables, wherein each of the divisions provides a plurality of compression pressure variables indicative of each of the compression pressures of the plurality of cylinders in said multi-cylinder reciprocating engine.

A method of compression pressure determination in a combustion chamber of a cylinder in a reciprocating engine, said method comprising the steps of:

• measuring a first engine crankshaft acceleration, proximate an engine crankshaft angle centered proximate a maximum rate of compression in the cylinder, and providing a first engine crankshaft acceleration reading;
• measuring a second engine crankshaft acceleration, proximate an engine crankshaft angle corresponding to the cylinder's top-dead-center position, and providing a second engine crankshaft acceleration reading;
• measuring an absolute pressure at an intake manifold coincident with the measurement of the first predetermined engine crankshaft angle and providing a pressure variable associated with the presently combusting cylinder;
• subtracting the first engine crankshaft acceleration reading from the second engine crankshaft acceleration reading and dividing the difference by the pressure variable and providing a compression pressure variable indicative of pressure in the combusting cylinder;
• and
• providing a low compression indication when the compression pressure variable, provided in said step of subtracting and dividing does not exceed a predetermined combustion pressure threshold.

An apparatus for determining compression pressure of a cylinder in a running engine, said apparatus comprising:

• means for measuring acceleration of a crankshaft of said running engine centered proximate a maximum rate of compression of said cylinder, and providing a first acceleration variable responsive thereto;
• means for measuring an intake manifold pressure of said running engine, and providing an intake manifold pressure variable responsive thereto;
• and
• means for providing a compression pressure variable indicative of a compression pressure in the combustion chamber of the cylinder in said running engine, by dividing the first acceleration variable by the measured intake manifold pressure variable.

An apparatus for determining compression pressure in a combustion chamber of a cylinder in a running engine, said apparatus comprising:

• means for measuring an intake manifold pressure of said running engine associated with a pressure of air ingested into the combustion chamber of the cylinder, and providing an intake manifold pressure variable responsive thereto;
• means for measuring a first acceleration of a crankshaft of said running engine, coincident with a compression cycle of the cylinder and providing a first acceleration variable responsive thereto, and for measuring a second acceleration of the crankshaft of said running engine coincident proximate the cylinder's top-dead-center position and providing a second acceleration variable responsive thereto;
• and
• means for providing a compression pressure variable having a magnitude indicative of a compression pressure in said combustion chamber of the cylinder determined dependent on an amplitude of the first acceleration variable, and an amplitude of the second acceleration variable, and the measured intake manifold pressure variable.

An apparatus for determnining compression pressure in a combustion chamber of a cylinder in a running engine, said apparatus comprising:

• means for measuring an intake manifold pressure of said running engine associated with a pressure of air ingested into the combustion chamber of the cylinder, and providing an intake manifold pressure variable responsive thereto;
• means for measuring a first acceleration of a crankshaft of said running engine, coincident with a compression cycle of the cylinder and providing a first acceleration variable responsive thereto, and for measuring a second acceleration of the crankshaft of said running engine coincident proximate the cylinder's top-dead-center position and providing a second acceleration variable responsive thereto;
• and
• means for providing a compression pressure variable indicative of a compression pressure in said combustion chamber of the cylinder by subtracting the first acceleration variable from the second acceleration variable and dividing the difference by the intake manifold pressure variable, wherein the division provides a compression pressure variable indicative of a compression pressure in the combustion chamber of the cylinder.

An apparatus for determining compression pressure in a multi-cylinder reciprocating engine, said apparatus comprising:

• means for measuring an intake manifold pressure for each of a plurality of cylinders in said multi-cylinder reciprocating engine, and providing a plurality of intake manifold pressure variables responsive thereto for each of the plurality of cylinders;
• means for measuring a first acceleration of a crankshaft for each of the plurality of cylinders in said multi-cylinder reciprocating engine and for providing a plurality of first acceleration variables responsive thereto, and, later in time, for measuring a second acceleration of the crankshaft for each of the plurality of cylinders in said reciprocating engine and for providing a plurality of second acceleration variables responsive thereto;
• and
• means for subtracting each of the plurality of first acceleration variables from each of the plurality of second acceleration variables and for dividing each of the plurality of differences by each of the plurality of intake manifold pressure variables, wherein each of the divisions provides a plurality of compression pressure variables indicative of each of the compression pressures of the plurality of cylinders in said multi-cylinder reciprocating engine.

An apparatus for determining compression pressure in a combustion chamber of a cylinder in a reciprocating engine, said apparatus comprising:

• an accelerometer for measuring engine crankshaft acceleration at an engine crankshaft angle centered proximate a maximum rate of compression in the cylinder and for providing a first engine crankshaft acceleration reading, and for measuring a second engine crankshaft acceleration at an engine crankshaft angle corresponding to the cylinder's top-dead-center position and for providing a second engine crankshaft acceleration reading;
• an absolute pressure sensor measuring an absolute pressure at an intake manifold coincident with the measurement of the first predetermined engine crankshaft angle and providing a pressure variable associated with the presently combusting cylinder;
• and
• a control device for subtracting the first engine crankshaft acceleration reading from the second engine crankshaft acceleration reading and dividing the difference by the pressure variable and providing a compression pressure variable indicative of pressure in the combusting cylinder, and for providing a low compression indication when the compression pressure variable does not exceed a predetermined combustion pressure threshold.