Engine operation to estimate and control exhaust catalytic converter temperature
First Claim
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1. A method of operating an internal combustion engine wherein the method of operating the engine includes using a predicted exhaust gas temperature in conjunction with fuel scheduling for the engine and ignition timing for the engine and choosing a spark value so as to adjust an actual exhaust gas temperature and maintain the actual exhaust gas temperature within limits.
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Abstract
A method of operating an internal combustion engine wherein a predicted engine exhaust temperature is used as an input to a microprocessor controlling the engine. Exhaust temperature can be controlled by adjusting engine operation. Exhaust gas recirculation mass flow can be more accurately determined using the predicted engine exhaust temperature.
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Citations
11 Claims
- 1. A method of operating an internal combustion engine wherein the method of operating the engine includes using a predicted exhaust gas temperature in conjunction with fuel scheduling for the engine and ignition timing for the engine and choosing a spark value so as to adjust an actual exhaust gas temperature and maintain the actual exhaust gas temperature within limits.
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3. A method of inferring engine exhaust gas temperature including:
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providing inputs indicating air/fuel ratio, exhaust gas recirculation rate, spark timing, air charge intake, engine speed rpm; providing stored look-up tables indicating air/fuel ratio versus a first constant, air/fuel ratio versus a second constant, exhaust gas recirculation (EGR) versus a third constant, engine aircharge versus a fourth constant, engine rpm and engine aircharge versus MBT, engine rpm and engine discharge versus nominal exhaust temperature; multiplying an output from the EGR rate sensor and an output of the engine aircharge versus the fourth constant table to produce a first product; adding the output from the table of air/fuel ratio versus the second constant, the product, and an output of the rpm versus MBT table to produce a first sum; finding a difference between the spark timing input and the first sum; applying the difference to a table for spark delay versus constant; multiplying an output of the spark delay table by the output of the EGR versus constant table and the rpm versus nominal exhaust temperature table to produce a second product; multiplying the second product by an output of the air/fuel ratio versus constant to produce a third product of the exhaust temperature; providing stored tables and memory for adjusting exhaust temperature as a function of air/fuel ratio, exhaust gas recirculation, spark delay and engine speed; coupling an input indicating air/fuel ratio to information stored as a function of air/fuel ratio; coupling an input indicating EGR rate to information stored as a function of EGR; coupling an input indicating air charge to information stored as a function of air charge and engine speed; coupling engine speed to information stored as a function of engine speed; multiplying the output of information stored as a function of air charge and an input indicating exhaust gas recirculation and applying the output to a first adder; applying the output of information stored as a function of air/fuel ratio and information stored as a function of engine speed to the first adder; applying an input indicating spark timing to the negative input of a difference module and applying output of the first adder to the positive input of the difference module; applying the output of the difference module to an exhaust temperature adjustment table stored as a function of spark retard; applying the output of the exhaust temperature adjustment table to a second multiplier along with information stored as a function of exhaust gas recirculation, engine speed stored as a function of spark retard to provide an output indicative of exhaust temperature.
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4. A method of inferring engine exhaust gas temperature including:
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providing inputs indicating engine speed and engine aircharge; providing look-up tables stored in memory including a first look-up table indicating an exhaust gas recirculation constant versus aircharge, a second look-up table indicating MBT spark versus engine speed, a third look-up table indicating nominal exhaust temperature (EXT) versus engine speed, and a fourth look-up table indicating a constant versus spark delay; applying an input indicating aircharge to said first, second, and third tables; applying an input indicating engine speed to said second and third tables; applying outputs from said first and second tables to a first summer; applying an output of said first summer as an input to said fourth table; applying an output of said fourth table to a first multiplier; applying an output of said third table to said first multiplier; and using an output of said first multiplier as an indication of exhaust gas temperature. - View Dependent Claims (5, 6, 7)
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- 8. A method of operating an internal combustion engine wherein the method of operating the engine includes using a predicted exhaust gas temperature in conjunction with determining an exhaust gas recirculation mass flow rate.
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11. A method of operating an internal combustion engine wherein the method of operating the engine includes:
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using a predicted exhaust gas temperature in conjunction with determining an exhaust gas recirculation mass flow rate;
determining exhaust gas recirculation mass flow rate (EM) using;
space="preserve" listing-type="equation">EM=EGR-MASS-STP*SQRT[BP % PEXH)-29.92]*SQRT [1460/(EGT-EGRORIF %
460)]wherein;
p2 EGR-MASS-STP--exhaust gas recirculation mass flow at a predetermined or standard temperature and pressureBP--barometric pressure PEXH--exhaust gas pressure SQRT--square root function EGT--exhaust gas temperature EGRORIF--exhaust gas temperature at the metering orifice of the exhaust gas recirculation valve 29.92--barometric pressure 1460 DEG.Rankin--temperature of the exhaust gas at the metering orifice 1000 DEG.Fahrenheit--temperature of exhaust gas at the metering orifice providing inputs indicating air/fuel ratio, exhaust gas recirculation rate, spark timing, air charge intake, engine speed rpm; providing stored look-up tables indicating air/fuel ratio versus a first constant, air/fuel ratio versus a second constant, exhaust gas recirculation (EGR) versus a third constant, engine aircharge versus a fourth constant, engine rpm and engine aircharge versus MBT, engine rpm and engine discharge versus nominal exhaust temperature; multiplying an output from the EGR rate sensor and an output of the engine aircharge versus the fourth constant table to produce a first product; adding the output from the table of air/fuel ratio versus the second constant, the product, and an output of the rpm versus MBT table to produce a first sum; finding a difference between the spark timing input and the first sum; applying the difference to a table for spark delay versus constant; multiplying an output of the spark delay table by the output of the EGR versus constant table and the rpm versus nominal exhaust temperature table to produce a second product; multiplying the second product by an output of the air/fuel ratio versus constant to produce a third product of the exhaust temperature; providing stored tables and memory for adjusting exhaust temperature as a function of air/fuel ratio, exhaust gas recirculation, spark delay and engine speed; coupling an input indicating air/fuel ratio to information stored as a function of air/fuel ratio; coupling an input indicating from EGR rate to information stored as a function of EGR; coupling an input indicating air charge to information stored as a function of air charge and engine speed; coupling engine speed to information stored as a function of engine speed; multiplying the output of information stored as a function of air charge and an input indicating exhaust gas recirculation and applying the output to a first adder; applying the output of information stored as a function of air/fuel and information stored as a function of engine speed to the first adder; applying an input indicating spark timing to the negative input of a difference module and applying output of the first adder to the positive input of the difference module; applying the output of the difference module to an exhaust temperature adjustment table stored as a function of spark retard; applying the output of the exhaust temperature adjustment table to a second multiplier along with information stored as a function of exhaust gas recirculation, engine speed stored as a function of spark retard to provide an output indicative of exhaust temperature.
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Specification