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.
85 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