JP2023046837A - Control device for internal combustion engine - Google Patents

Abstract

To suppress deviation between actual discharge amount and a calculated discharge amount of particulate matter.SOLUTION: A CPU 72 executes processing for calculating a discharge amount of particulate matter discharged from a combustion chamber 20 to an exhaust passage 30 of an internal combustion engine 10. The CPU 72 further executes processing for measuring the number of times of injection required from start of fuel injection until an air-fuel mixture is ignited at starting of the engine, and processing for correcting the discharge amount so that the calculated discharge amount is larger when the number of times of injection is large than when the number of times of injection is small.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device for an internal combustion engine.

For example, the control device described in Patent Literature 1 calculates the amount of particulate matter discharged from the combustion chamber of the internal combustion engine to the exhaust passage based on the engine rotation speed, the engine load, and the like.

Japanese Patent Application Laid-Open No. 2001-280118

When calculating the emission amount of particulate matter as described above, the calculation model is adapted on the assumption that the heaviness of the fuel of the internal combustion engine is within a predetermined range. The heaviness of the fuel is a value indicated by, for example, the 50% distillation temperature. As the fuel becomes heavier, the amount of particulate matter generated in the combustion chamber of the internal combustion engine tends to increase.

Therefore, if fuel with a higher degree of heaviness than the assumed range is used, there is a possibility that the discrepancy between the actual emission amount of particulate matter and the calculated emission amount will increase.

A control device for an internal combustion engine that solves the above problems executes a process of calculating the amount of particulate matter discharged from a combustion chamber of the internal combustion engine to an exhaust passage. This control device measures the number of injections required from the start of fuel injection at engine startup until the mixture ignites, and when the number of injections is large, compared to the case where the number of injections is small. , and a process of correcting the emission amount so that the calculated emission amount increases.

The higher the fuel's heaviness, the lower the fuel's volatility. Therefore, when the engine is started, the number of injections required from the start of fuel injection until the mixture ignites tends to increase. Therefore, in the same configuration, when the number of times of injection is large, compared to when the number of times of injection is small, the emission amount of particulate matter is corrected so that the calculated amount of emission of particulate matter is larger. Therefore, the emission amount of particulate matter is calculated according to the degree of heaviness of the fuel. Therefore, the divergence between the actual emission amount of particulate matter and the calculated emission amount can be suppressed.

1 is a diagram showing configurations of an internal combustion engine, a drive system, and a control device according to one embodiment; FIG. It is a flowchart which shows the processing procedure which the control apparatus of the same embodiment performs.

<Configuration of Internal Combustion Engine, Drive System, and Control Device>
An embodiment of a control device for an internal combustion engine will be described below with reference to the drawings.
As shown in FIG. 1, the internal combustion engine 10 has four cylinders, for example cylinder #1 to cylinder #4.

A throttle valve 14 is provided in an intake passage 12 of the internal combustion engine 10 .
An intake port 12a, which is a downstream portion of the intake passage 12, is provided with a port injection valve 16 for injecting fuel into the intake port 12a. Air taken into the intake passage 12 and fuel injected from the port injection valve 16 flow into the combustion chamber 20 as the intake valve 18 opens.

A cylinder head of the internal combustion engine 10 is provided with an in-cylinder injection valve 22 that injects fuel directly into the combustion chamber 20 .
The air-fuel mixture in the combustion chamber 20 is combusted by the spark discharge of the ignition plug 24 . The combustion energy generated at that time is converted into rotational energy of the crankshaft 26 .

The air-fuel mixture combusted in the combustion chamber 20 is discharged to the exhaust passage 30 as exhaust as the exhaust valve 28 is opened. The exhaust passage 30 is provided with a three-way catalyst 32 having an oxygen storage capacity and a gasoline particulate filter (GPF 34) that collects particulate matter (hereinafter referred to as PM) in the exhaust. In this embodiment, it is assumed that the GPF 34 is a filter that collects PM and supports a three-way catalyst.

The crankshaft 26 is mechanically connected to a carrier C of a planetary gear mechanism 50 that constitutes a power split device. The sun gear S of the planetary gear mechanism 50 is mechanically connected to the rotating shaft 52 a of the first motor generator 52 . Further, the ring gear R of the planetary gear mechanism 50 is mechanically connected to the rotating shaft 54 a of the second motor generator 54 and the drive wheel 60 . An AC voltage is applied to terminals of the first motor generator 52 by an inverter 56 . An AC voltage is applied to terminals of the second motor generator 54 by an inverter 58 .

The control device 70 controls the internal combustion engine 10, and controls the throttle valve 14, the port injection valve 16, the in-cylinder injection valve 22, the spark plug 24, etc. in order to control the torque, the exhaust gas component ratio, etc. as the control amount. , various operation units of the internal combustion engine 10 are operated. Further, the control device 70 controls the first motor generator 52 and operates the inverter 56 so as to control the rotation speed, which is the control amount thereof. Further, the control device 70 controls the second motor generator 54 and operates the inverter 58 to control the torque, which is the control amount of the second motor generator 54 . FIG. 1 shows operation signals MS1 to MS6 for the throttle valve 14, the port injection valve 16, the in-cylinder injection valve 22, the spark plug 24, and the inverters 56, 58, respectively.

The control device 70 refers to the intake air amount Ga detected by the air flow meter 80, the output signal Scr of the crank angle sensor 82, and the water temperature THW detected by the water temperature sensor 86 in order to control the control amount of the internal combustion engine 10. . The control device 70 also refers to the vehicle speed SP detected by the vehicle speed sensor 84 and the pressure Pex of the exhaust flowing into the GPF 34 which is a value detected by the exhaust pressure sensor 88 . In addition, in order to control the amount of control of the first motor generator 52 and the second motor generator 54, the control device 70 outputs an output signal Sm1 of the first rotation angle sensor 90 that detects the rotation angle of the first motor generator 52, and The output signal Sm2 of the second rotation angle sensor 92 that detects the rotation angle of the second motor generator 54 is referred to.

The control device 70 includes a CPU 72 , a ROM 74 , a storage device 75 , and a peripheral circuit 76 , which can communicate with each other through a communication line 78 . Here, the peripheral circuit 76 includes a circuit that generates a clock signal that defines internal operations, a power supply circuit, a reset circuit, and the like. The control device 70 controls the control amount by causing the CPU 72 to execute programs stored in the ROM 74 .

<Processing executed by the control device>
Control device 70 calculates engine speed NE based on output signal Scr. The control device 70 also calculates the engine load factor KL. The engine load factor KL is a parameter that determines the amount of air charged into the combustion chamber 20, and is the ratio of the inflow air amount per cylinder per combustion cycle to the reference inflow air amount. Note that the reference inflow air amount may be an amount that is variably set according to the engine speed NE.

The control device 70 calculates a PM discharge amount PMd, which is the amount of PM discharged from the combustion chamber 20 to the exhaust passage 30, at predetermined intervals. That is, the control device 70 calculates the base value PMb of the PM discharge amount PMd based on the engine speed NE, the engine load factor KL, and the water temperature THW at predetermined intervals. Then, the PM emission amount PMd is calculated by multiplying the base value PMb by a correction value H, which will be described later (PMd=PMb×H).

In addition, the control device 70 calculates a PM regeneration amount PMs, which is the amount of PM removed from the GPF 34, based on the temperature of the GPF 34 and the like at predetermined intervals. Based on the PM emission amount PMd and the PM regeneration amount PMs, which are thus calculated for each predetermined cycle, the control device 70 calculates the PM accumulation amount DPM, which is the amount of PM accumulated in the GPF 34 .

FIG. 2 shows processing executed by the control device 70 to calculate the correction value H. As shown in FIG. Note that this processing is started by the CPU 72 of the control device 70 when the engine starting of the internal combustion engine 10 is started. Incidentally, when the engine starting of the internal combustion engine 10 is started, cranking of the crankshaft 26, fuel injection from the fuel injection valve, and ignition by the ignition plug are started. Also, hereinafter, the step number of each process is represented by a number prefixed with "S".

In the series of processes shown in FIG. 2, the CPU 72 first determines whether or not the starting water temperature THWs, which is the water temperature THW at engine starting, is equal to or less than a predetermined determination value THWsref (S100). The ignitability of the air-fuel mixture at engine start-up is more likely to be affected by the heavyness of the fuel in the internal combustion engine 10 as the water temperature THWs at start-up is lower. Therefore, as the reference value THWsref, a water temperature that is likely to be affected by the degree of heaviness of the fuel is set in advance. The heaviness of the fuel is a value indicated by, for example, the 50% distillation temperature. Therefore, the startability of the internal combustion engine 10 deteriorates. In addition, when the degree of heaviness of the fuel increases, the amount of PM generated in the combustion chamber 20 increases, and the amount of PM emissions tends to increase.

If it is determined that the starting water temperature THWs is equal to or lower than the determination value THWsref (S100: YES), the CPU 72 starts measuring the number of times of injection N (S110). The number of injections N is the number of fuel injections after the start of fuel injection when the engine is started. When fuel is injected from both the port injection valve 16 and the in-cylinder injection valve 22, i.e., when so-called split injection is performed at engine start-up, either the port injection valve 16 or the in-cylinder injection valve 22 is used. The number of times of one injection is counted as the number of times N of injections. Further, when the measurement of the number of times N of injections has already started at the time of execution of S110, the CPU 72 continues the measurement of the number of times N of injections.

Next, the CPU 72 determines whether or not the air-fuel mixture has ignited for the first time after starting the engine (S120). The ignition determination in S120 can be performed as appropriate. For example, an affirmative determination may be made when the engine speed NE is equal to or higher than a predetermined determination value. Alternatively, an affirmative determination may be made when the amount of increase in the engine speed NE is greater than or equal to a predetermined determination value. Alternatively, if an in-cylinder pressure sensor that detects the pressure in the combustion chamber 20 is provided, affirmative determination may be made when the pressure detected by the in-cylinder pressure sensor exceeds a predetermined determination value.

If the determination in S120 is negative, that is, if the air-fuel mixture has not yet ignited after the start of the engine, the CPU 72 substitutes the current injection number N for the non-ignition number Nnf (S130 ). The initial value of the non-firing count Nnf is "0". Then, the CPU 72 repeatedly executes the processes of S120 and S130 until an affirmative determination is made in S120.

When the determination in S120 is affirmative, the CPU 72 acquires the current number of non-ignition times Nnf (S140). The value of the number of unfired times Nnf acquired here indicates the number of times of injection required from the start of fuel injection until the mixture ignites at engine startup.

Next, the CPU 72 calculates the correction value H based on the number of unfired times Nnf (S150). In the process of S150, the CPU 72 calculates the correction value H so that the correction value H increases as the number of non-ignition times Nnf increases. Note that the correction value H is a value equal to or greater than "1", and the larger the correction value H, the larger the value of the PM discharge amount PMd that is calculated.

Then, when the process of S150 is finished, or when a negative determination is made in the process of S100, the CPU 72 finishes the series of processes shown in FIG.
<Action and effect>
The action and effect of this embodiment will be described.

(1) As the weight of the fuel increases, the volatility of the fuel decreases. Therefore, when the engine is started, the number of injections required from the start of fuel injection to the ignition of the air-fuel mixture tends to increase. Therefore, the correction value H to be multiplied by the base value PMb of the PM discharge amount PMd is calculated as follows. That is, the larger the number of non-ignition times Nnf, the larger the correction value H. Therefore, when the number of non-ignitions Nnf is large, the calculated PM emission amount PMd is corrected so as to be larger than when it is small. Therefore, the PM emission amount PMd is calculated according to the degree of weight of the fuel. Therefore, it is possible to suppress the divergence between the actual emission amount of PM and the calculated emission amount.

It should be noted that the above embodiment can be implemented with the following modifications. The above embodiments and the following modifications can be combined with each other within a technically consistent range.

・Measure the number of cycles required from the start of fuel injection to the ignition of the air-fuel mixture when the engine is started. Then, the measured number of cycles may be used as a substitute value for the number of non-ignition times Nnf.

・Measure the number of ignitions required from the start of ignition of the air-fuel mixture until the air-fuel mixture ignites when the engine is started. Then, the measured number of ignitions may be used as a substitute value for the number of non-ignitions Nnf.

・Measure the time required from the start of the engine to the ignition of the air-fuel mixture. Then, the correction value H may be calculated such that the longer the measured time, the larger the correction value H becomes. In the case of this modification, the voltage of the battery that supplies electric power to the motor that cranks the internal combustion engine 10 affects the measurement time. Therefore, for example, the voltage of the battery during cranking is acquired. Then, the measured time and the correction value H may be corrected according to the acquired battery voltage.

• Measure the time T required from the start of fuel injection to the ignition of the air-fuel mixture when the engine is started. Then, based on the measured time T and the engine speed NE during cranking, the number of rotations of the crankshaft 26 from the start of fuel injection to the ignition of the air-fuel mixture is calculated. Then, by multiplying the calculated number of rotations by "2", the number of non-ignition times Nnf may be calculated.

- The correction value H is multiplied by the base value PMb calculated at each predetermined cycle. In addition, the total fuel injection amount during one trip is calculated. Then, by multiplying the calculated total fuel injection amount by the correction value H, the total PM emission amount PMd during one trip may be calculated.

- A PM sensor for measuring the amount of PM is provided on the upstream side of the GPF 34 . Then, the correction value H may be calculated from the difference between the actual PM emission amount PMr measured by the PM sensor and the calculated PM emission amount PMd.

- The correction value H calculated after refueling may be used as it is without being updated until the next refueling. The calculated correction value H may also be used to calculate the PM emission amount PMd after the warm start.

The PM deposition amount DPM calculated from the above-mentioned PM discharge amount PMd, PM regeneration amount PMs, etc. is set as a first PM deposition amount DPM1. Also, let the PM deposition amount calculated based on the pressure difference between the upstream side and the downstream side of the GPF 34 be a second PM deposition amount DPM2. Then, the correction value H may be calculated based on the difference between the first PM deposition amount DPM1 and the second PM deposition amount DPM2. When the correction value H is calculated in this modified example and in the process of S150, for example, one of the correction values H may be invalidated.

- The GPF 34 is not limited to a filter carrying a three-way catalyst, and may be a filter alone. Further, the GPF 34 is not limited to one provided downstream of the three-way catalyst 32 in the exhaust passage 30 . Also, the three-way catalyst 32 may be replaced with an oxidation catalyst that oxidizes the components contained in the exhaust gas.

- The control device is not limited to one that includes the CPU 72 and the ROM 74 and executes software processing. For example, a dedicated hardware circuit such as an ASIC may be provided to perform hardware processing at least part of what is software processed in the above embodiments. That is, the control device may have any one of the following configurations (a) to (c). (a) A processing device that executes all of the above processes according to a program, and a program storage device such as a ROM that stores the program. (b) A processing device and a program storage device for executing part of the above processing according to a program, and a dedicated hardware circuit for executing the remaining processing. (c) provide dedicated hardware circuitry to perform all of the above processing; Here, there may be a plurality of software execution devices provided with a processing device and a program storage device, or a plurality of dedicated hardware circuits.

- The vehicle is not limited to a series/parallel hybrid vehicle, and may be, for example, a parallel hybrid vehicle or a series hybrid vehicle. However, the vehicle is not limited to a hybrid vehicle, and may be a vehicle having only the internal combustion engine 10 as a power generation device of the vehicle, for example.

DESCRIPTION OF SYMBOLS 10... Internal combustion engine 12... Intake passage 12a... Intake port 14... Throttle valve 16... Port injection valve 18... Intake valve 20... Combustion chamber 22... In-cylinder injection valve 24... Spark plug 26... Crankshaft 28... Exhaust valve 30... Exhaust Passage 32 Three-way catalyst 34 GPF
50... Planetary gear mechanism 52... First motor generator 54... Second motor generator 60... Drive wheel 70... Control device 72... CPU
74 ROM
80 Air flow meter 82 Crank angle sensor 86 Water temperature sensor 88 Exhaust pressure sensor

Claims (1)

A control device that executes a process of calculating an amount of particulate matter discharged from a combustion chamber of an internal combustion engine to an exhaust passage,
A process of measuring the number of injections required from the start of fuel injection at engine startup until the mixture ignites;
A control device for an internal combustion engine that corrects the emission amount so that the calculated emission amount increases when the number of injections is high compared to when the number of injections is low.

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