JP2022063656A - Internal combustion engine control device - Google Patents

Abstract

To prevent fluctuation of torque due to inhomogeneous fuel injections into respective cylinders while dither control is in execution from being sensed by an occupant, etc.SOLUTION: A CPU 32 of a control device 30 at least performs dither control in a manner that uses a portion of a plurality of cylinders of an internal combustion engine 10 as rich combustion cylinders with an air-fuel ratio richer than a theoretical air-fuel ratio and remaining cylinders as lean combustion cylinders with the air-fuel ratio leaner than the theoretical air-fuel ratio when a request is made for a reproduction process of a GPF 26 installed at an exhaust side of an internal combustion engine 10. Also, while the dither control is in execution, the CPU switches cylinders to be used as the rich combustion cylinders among the plurality of cylinders in a random or quasi-random pattern.SELECTED DRAWING: Figure 1

Description

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

Patent Document 1 describes a control device for an internal combustion engine that performs the following control. That is, when filter regeneration processing is required due to an increase in the amount of PM (Particulate Matter) collected by the GPF (Gasoline Particulate Filter), one of cylinders # 1 to # 4 has a theoretical air-fuel ratio. Dither control is performed with a rich combustion cylinder that is richer than the theoretical air-fuel ratio and a lean combustion cylinder that is leaner than the stoichiometric air-fuel ratio. In addition, dither control is executed even when warm-up of the three-way catalyst is requested, and compared to dither control when warm-up is requested, the dither control during filter regeneration processing is the air-fuel ratio in the rich combustion cylinder and the air in the lean combustion cylinder. Increase the time integration value of the absolute value of the difference from the fuel ratio.

Japanese Unexamined Patent Publication No. 2019-060302

Although the technique described in Patent Document 1 can suppress the torque fluctuation (torque step) of the internal combustion engine generated when switching from the normal control for making the fuel injection amount to each cylinder uniform to the dither control, the dither control is being carried out. In addition, torque fluctuations caused by non-uniform fuel injection to each cylinder cannot be suppressed.

That is, in the technique described in Patent Document 1, the state in which the specific cylinder is the rich combustion cylinder and the other cylinders other than the specific cylinder are the lean combustion cylinders is continued for several cycles during the implementation of dither control. As a result, the torque fluctuation once every two rotations of the crank shaft (rotation 0.5th order) is repeated several times, in which the torque is large when the specific cylinder is burned and the torque is small when the other cylinders are burned. (Torque fluctuation) will occur.

The present disclosure has been made in consideration of the above facts, and an object of the present invention is to obtain a control device for an internal combustion engine capable of suppressing the detection of torque fluctuation during dither control.

The control device for an internal combustion engine according to the first aspect is theoretically empty of a part of a plurality of cylinders of the internal combustion engine when at least a regeneration process of a filter provided on the exhaust side of the internal combustion engine is required. The dither control is performed so that the rich combustion cylinder is richer than the fuel ratio and the rest is the lean combustion cylinder leaner than the stoichiometric air-fuel ratio. It includes a control unit that switches the cylinders to be used in a random or random pattern.

In the first aspect, during the implementation of dither control, the cylinder to be the rich combustion cylinder among the plurality of cylinders is switched at random or in a pattern according to random. As a result, in the rotation of the crank shaft of the internal combustion engine, the timing at which combustion occurs in the rich combustion cylinder, that is, the timing at which the torque of the internal combustion engine increases, changes in a random or random pattern, so that the torque fluctuation of the internal combustion engine changes. It is distributed to various orders. Therefore, according to the first aspect, it is possible to suppress the torque fluctuation caused by the non-uniform fuel injection amount to each cylinder from being perceived by the occupant or the like during the implementation of dither control. ..

The present disclosure has the effect that torque fluctuations can be suppressed from being sensed during dither control.

It is a schematic block diagram of an internal combustion engine, a control device and its periphery which concerns on embodiment. It is a block diagram which shows a part of the processing executed by a control device. It is a flowchart which shows an example of the dither control cylinder selection process. It is a flowchart which shows the other example of the dither control cylinder selection process. It is a diagram which shows the transmission characteristic at each response point of the power train which concerns on Example. It is a diagram which shows the torque fluctuation by the conventional dither control. It is a diagram which shows the torque fluctuation by the dither control of this disclosure.

Hereinafter, an example of the embodiment of the present disclosure will be described in detail with reference to the drawings.

In the internal combustion engine 10 shown in FIG. 1, the air sucked from the intake passage 12 flows into the combustion chambers 16 of the cylinders # 1 to # 4 via the intake valve INV. Cylinders # 1 to # 4 are each provided with a fuel injection valve 18 for injecting fuel and an ignition device 20 for generating spark discharge. In the combustion chamber 16, the air-fuel mixture is subjected to combustion, and the air-fuel mixture used for combustion is discharged to the exhaust passage 22 as exhaust gas when the exhaust valve EXV is opened. The exhaust passage 22 is provided with a three-way catalyst 24 having an oxygen storage capacity. Further, a gasoline particulate filter (GPF) 26 is provided on the downstream side of the three-way catalyst 24 in the exhaust passage 22.

The control device 30 targets the internal combustion engine 10 as a control target, and operates an operation unit of the internal combustion engine 10 such as a fuel injection valve 18 and an ignition device 20 in order to control a controlled amount (torque, exhaust component, etc.) thereof. At this time, the control device 30 has an air fuel ratio Af detected by the air fuel ratio sensor 40 provided on the upstream side of the ternary catalyst 24, and an upstream pressure (upstream pressure) of the GPF 26 detected by the upstream pressure sensor 42. Pu) and the downstream pressure (downstream pressure Pd) of the GPF 26 detected by the downstream pressure sensor 44 are referred to. Further, the control device 30 includes an output signal Scr of the crank angle sensor 46, an intake air amount Ga detected by the air flow meter 48, a cooling water temperature (water temperature THW) of the internal combustion engine 10 detected by the water temperature sensor 50, and a water temperature THW. The amount of depression of the accelerator pedal (accelerator operation amount ACCP) detected by the accelerator sensor 52 is referred to.

The control device 30 includes a CPU 32, a ROM 34, and a RAM 36, and the control program 35 is stored in the ROM 34. The control device 30 functions as a control unit according to the present disclosure when the control program 35 is read from the ROM 34 and expanded in the RAM 36, and the control program 35 expanded in the RAM 36 is executed by the CPU 32. To control.

FIG. 2 shows a part of the processing realized by the CPU 32 executing the control program 35 stored in the ROM 34.

The misfire detection process M10 is a process for determining the presence or absence of a misfire based on the output signal Scr. The misfire detection process M10 includes a process of tentatively determining that a misfire occurs when the rotation fluctuation amount Δω is equal to or less than a negative threshold value based on the output signal Scr. Here, the rotation fluctuation amount Δω is the rotation speed (instantaneous rotation speed ω) at predetermined angular intervals including the compression top dead center only once, and the appearance timing of the compression top dead center is adjacent to each other in time series. It is a value obtained by subtracting the value in the cylinder in which the compression top dead center appears later from the value in the cylinder in which the compression top dead center appears first. The misfire detection process M10 makes a final determination that a misfire has occurred when the number of tentative determinations exceeds the threshold value while the crank shaft of the internal combustion engine 10 rotates a predetermined number of times, and the warning lamp shown in FIG. It includes a process of operating 54 to notify the user. The misfire detection process M10 includes a process of resetting the history of provisional determination every predetermined number of times.

The base injection amount calculation process M12 controls the open loop with the air-fuel ratio of the air-fuel mixture in the combustion chamber 16 as the target air-fuel ratio based on the rotation speed NE calculated based on the output signal Scr of the crank angle sensor 46 and the intake air amount Ga. This is a process of calculating the base injection amount Qb as the open loop operation amount, which is the operation amount for the operation.

The target value setting process M14 is a process of setting a target value Af * of a feedback control amount for controlling the air-fuel ratio of the air-fuel mixture in the combustion chamber 16 to the above target air-fuel ratio.

The feedback process M16 is a process for calculating the feedback manipulated variable KAF, which is the manipulated variable for feedback controlling the air-fuel ratio Af, which is the feedback controlled variable, to the target value Af *. In the present embodiment, the sum of the output values of the proportional element, the integral element, and the differential element that input the difference between the target value Af * and the air-fuel ratio Af is set as the correction ratio δ of the base injection amount Qb, and the feedback operation amount KAF. Is set to "1 + δ".

The feedback correction process M18 is a process of correcting the base injection amount Qb by multiplying the base injection amount Qb by the feedback operation amount KAF and calculating the required injection amount Qd.

The required value output processing M20 targets the air-fuel ratio of the air-fuel mixture for which the components of the entire exhaust gas discharged from each of the cylinders # 1 to # 4 of the internal combustion engine 10 are to be burned in all the cylinders # 1 to # 4. The injection amount correction request value α of the dither control that makes the air-fuel ratio of the air-fuel mixture to be burned different between the cylinders is calculated and output while keeping the same as the case of the fuel ratio.

Here, in the dither control according to the present embodiment, the dither control cylinder selection process M29 is used to select one of the first cylinders # 1 to the fourth cylinder # 4 and the air-fuel ratio of the air-fuel mixture as the stoichiometric air-fuel ratio. It is selected as a rich combustion cylinder to be richer than, and the remaining three cylinders are set to lean combustion cylinders in which the air-fuel ratio of the air-fuel mixture is leaner than the stoichiometric air-fuel ratio. Then, the injection amount in the rich combustion cylinder is set to "1 + α" times the required injection amount Qd, and the injection amount in the lean combustion cylinder is set to "1- (α / 3)" times the required injection amount Qd.

According to the above injection amount settings for the lean combustion cylinder and the rich combustion cylinder, if the amount of air filled in each of the cylinders # 1 to # 4 is the same, each cylinder # 1 to # 4 of the internal combustion engine 10 The components of the entire exhaust gas discharged from the engine can be made equivalent to the case where the air-fuel ratio of the air-fuel mixture to be burned in all the cylinders # 1 to # 4 is set as the target air-fuel ratio. According to the above injection amount setting, if the amount of air filled in each of the cylinders # 1 to # 4 is the same, the reciprocal of the average value of the air-fuel ratio of the air-fuel mixture to be burned in each cylinder. Is the target air-fuel ratio. The air-fuel ratio is the reciprocal of the air-fuel ratio.

The correction coefficient calculation process M22 is a process of adding the injection amount correction request value α to “1” and calculating the correction coefficient of the required injection amount Qd for the rich combustion cylinder selected by the dither control cylinder selection process M29. .. The dither correction process M24 is a process of calculating the injection amount command value Q * of the cylinder #w which is regarded as the rich combustion cylinder by multiplying the required injection amount Qd of the rich combustion cylinder by the correction coefficient “1 + α”. Here, "w" means any one of "1" to "4".

The multiplication process M26 is a process of multiplying the injection amount correction request value α by "-1/3", and the correction coefficient calculation process M28 adds the output value of the multiplication process M26 to "1" to select a dither control cylinder. This is a process of calculating the correction coefficient of the required injection amount Qd with respect to the lean combustion cylinder set by the process M29. The dither correction process M30 multiplies the required injection amount Qd of the lean-burn cylinder by the correction coefficient "1- (α / 3)" to determine the injection amount of the cylinders # x, # y, # z as the lean-burn cylinder. This is a process for calculating the command value Q *. Here, "x", "y", and "z" are any of "1" to "4", and "w", "x", "y", and "z" are each other. It shall be different.

The injection amount operation process M32 generates an operation signal MS2 for the fuel injection valve 18 of the cylinder #w, which is regarded as a rich combustion cylinder, based on the injection amount command value Q * output by the dither correction process M24, and generates the same fuel injection valve. The fuel injection valve 18 is operated so that the fuel is output to 18 and the amount of fuel injected from the fuel injection valve 18 becomes an amount corresponding to the injection amount command value Q *. Further, the injection amount operation process M32 transmits the operation signal MS2 of the fuel injection valve 18 of the cylinders # x, # y, # z, which are considered to be lean burn cylinders, based on the injection amount command value Q * output by the dither correction process M30. It is generated, output to the fuel injection valve 18, and the fuel injection valve 18 is operated so that the amount of fuel injected from the fuel injection valve 18 becomes an amount corresponding to the injection amount command value Q *.

The sulfur poisoning amount calculation process M40 is a process of calculating the sulfur poisoning amount DS of the three-way catalyst 24 based on the rotation speed NE and the load factor KL. Specifically, for example, the higher the rotation speed NE and the higher the load factor KL, the larger the increase in the sulfur poisoning amount DS is calculated, and the increase is integrated to calculate the sulfur poisoning amount DS. be. Here, the load factor KL is a parameter indicating the amount of air filled in the combustion chamber 16, and is calculated by the CPU 32 based on the intake air amount Ga. The load factor KL is the ratio of the inflow air amount per combustion cycle of one cylinder to the reference inflow air amount. In the present embodiment, the reference inflow air amount is the inflow air amount per combustion cycle of one cylinder when the opening degree of the throttle valve 14 is maximized. Incidentally, the reference inflow air amount may be an amount variably set according to the rotation speed NE.

The deposit amount calculation process M42 is a process of calculating and outputting the amount of PM collected in the GPF 26 (PM deposit amount DPM) based on the upstream pressure Pu, the downstream pressure Pd, and the intake air amount Ga. In the deposit amount calculation process M42, the PM deposit amount DPM is set to a larger value than when the differential pressure obtained by subtracting the downstream side pressure Pd from the upstream side pressure Pu is high, and the PM deposit amount DPM is set to a larger value than when the intake air amount Ga is large. The PM deposition amount DPM is set to a small value.

Specifically, the ROM 34 stores map data in which the differential pressure and the intake air amount Ga are input variables and the PM accumulation amount DPM is an output variable, and the PM accumulation amount DPM is map-calculated by the CPU 32. The map data is a set of data of discrete values of input variables and values of output variables corresponding to the values of the input variables. In the map operation, for example, if the value of the input variable matches any of the values of the input variable of the map data, the value of the output variable of the corresponding map data is used as the operation result, and if they do not match, the value is included in the map data. The processing may be performed using the value obtained by interpolating the values of a plurality of output variables as the calculation result.

The base torque calculation process M44 is a process of calculating the base torque Trq0, which is the base value of the torque required for the internal combustion engine 10, based on the accelerator operation amount ACCP. More specifically, it is a process of calculating the base torque Trq0 to a larger value when the accelerator operation amount ACCP is large than when it is small.

The raising torque calculation process M46 is a process of calculating the raising torque ΔTrq for raising the base torque Trq0 based on the injection amount correction request value α. More specifically, when the injection amount correction request value α is zero, the raising torque ΔTrq becomes zero, and the larger the injection amount correction request value α is, the larger the raising torque ΔTrq is.

The required torque calculation process M48 is a process of calculating the required torque Trq * for the internal combustion engine 10 by adding the raising torque ΔTrq to the base torque Trq0.

The throttle operation process M50 is a process of generating an operation signal MS1 and outputting it to the throttle valve 14 in order to operate the opening degree of the throttle valve 14 based on the required torque Trq *. More specifically, it is a process of operating the opening degree of the throttle valve 14 to a larger value when the required torque Trq * is large than when it is small. The throttle operation process M50 according to the present embodiment is a process for setting the opening degree of the throttle valve 14 necessary for obtaining the required torque Trq * on the premise that the dither control is not executed. Therefore, when the dither control is executed, the torque is lower than when the air-fuel ratios of all the cylinders are the same. Therefore, the required torque Trq * is raised by using the raising torque ΔTrq.

That is, the raising torque ΔTrq is provided so that when the dither control is being executed, the throttle operation process M50 can be operated to the opening degree of the throttle valve 14 required to obtain the base torque Trq0. It is a thing. By the way, the torque is lower when the dither control is executed than when it is not executed. This is because the amount of torque reduction due to the weight loss correction is larger.

The required value output process M20 requests to warm up the three-way catalyst 24, to execute the sulfur poisoning recovery process of the three-way catalyst 24, and to execute the GPF 26 regeneration process (filter regeneration process). When the above occurs, the injection amount correction request value α is set to a value larger than zero.

The dither control according to the warm-up request and the execution request of the sulfur poisoning recovery treatment is performed by the reaction heat in the three-way catalyst 24 of the oxygen discharged from the lean combustion cylinder and the unburned fuel discharged from the rich combustion cylinder. This is a process for raising the temperature of the three-way catalyst 24. On the other hand, the temperature of the dither control in response to the execution request of the filter regeneration process increased due to the reaction heat in the three-way catalyst 24 of the oxygen discharged from the lean combustion cylinder and the unburned fuel discharged from the rich combustion cylinder. This is a process of raising the temperature of the GPF 26 by allowing the exhaust gas to flow into the GPF 26.

Further, the required value output process M20 sets the injection amount correction request value α when the execution request of the filter regeneration process occurs, the sulfur poisoning recovery of the three-way catalyst 24 when the warm-up request of the three-way catalyst 24 occurs, and the recovery of sulfur poisoning of the three-way catalyst 24. It is set to a larger value than when a processing execution request occurs. One of the reasons for this is that GPF 26 is located downstream of the three-way catalyst 24.

That is, the target temperature (for example, 550 ° C.) of the GPF 26 by dither control when the execution request of the filter regeneration process is generated is the three-way catalyst 24 by dither control when the execution request of the sulfur poisoning recovery process of the three-way catalyst 24 is generated. It is not necessarily high compared to the target temperature (for example, 650 ° C.). However, since the GPF 26 is located on the downstream side of the three-way catalyst 24, the dither control raising capacity required to raise the temperature of the GPF 26 to the target temperature becomes large.

Next, as the operation of the present embodiment, the details of the dither control cylinder selection process M29 will be described with reference to FIG. The dither control cylinder selection process M29 shown in FIG. 3 is repeatedly executed in a predetermined cycle (for example, a cycle shorter than one combustion cycle).

In step 100 of the dither control cylinder selection process M29, the CPU 32 determines whether or not dither control is being executed. For example, when the injection amount correction request value α output from the request value output process M20 is zero, the determination in step 100 is denied and the dither control cylinder selection process ends. In this case, since the injection amount correction required value α is zero, the air-fuel ratio of the air-fuel mixture in each cylinder is made uniform.

Further, for example, when the injection amount correction request value α output from the request value output process M20 is not zero, the determination in step 100 is affirmed and the process proceeds to step 102. In the present embodiment, the factors for executing the dither control are the case where the warm-up request of the three-way catalyst 24 is generated, the case where the execution request of the sulfur poisoning recovery process is generated, and the execution of the filter regeneration process. There are cases where a request has occurred and cases where there is a request. In step 102, the CPU 32 determines whether or not the factor for executing the dither control is a request for execution of the filter reproduction process.

If the determination in step 102 is affirmed, the process proceeds to step 104, and in step 104, the CPU 32 determines whether or not a time corresponding to one combustion cycle has elapsed since the last selection of the rich combustion cylinder. If the determination in step 104 is denied, the dither control cylinder selection process ends. If the determination in step 104 is affirmed, the process proceeds to step 106.

In step 106, the CPU 32 generates a random number. In the next step 108, the CPU 32 selects a rich combustion cylinder according to the random number generated in step 106, and outputs the required injection amount Qd of the selected rich combustion cylinder to the dither correction process M24. Specifically, for example, when the numerical range of the generated random number is 0 to 1, if the value of the generated random number is 0 or more and less than 0.25, cylinder # 1 is selected as the rich combustion cylinder, and the random number is generated. If the value is 0.25 or more and less than 0.5, select cylinder # 2 as the rich combustion cylinder, and if the random number value is 0.5 or more and less than 0.75, select cylinder # 3 as the rich combustion cylinder. If the value of the random number is 0.75 or more and 1.0 or less, cylinder # 4 is selected as the rich combustion cylinder.

In step 110, the CPU 32 sets the remaining cylinders other than the cylinder selected as the rich combustion cylinder in step 108 as the lean combustion cylinder, and outputs the required injection amount Qd of the set lean combustion cylinder to the dither correction process M30. When the process of step 110 is performed, the dither control cylinder selection process ends.

In this way, when the dither control is executed in response to the execution request of the filter regeneration process, the processes of steps 106 to 110 are executed every one combustion cycle, so that the rich combustion cylinder is randomly switched every one combustion cycle. It will be. As a result, in the rotation of the crank shaft of the internal combustion engine 10, the timing at which combustion occurs in the rich combustion cylinder, that is, the timing at which the torque of the internal combustion engine 10 increases, changes randomly, so that the torque fluctuation of the internal combustion engine 10 varies in various orders. Distributed to.

On the other hand, when the dither control is executed in response to the warm-up request of the three-way catalyst 24 or the execution request of the sulfur poisoning recovery treatment, the determination in step 102 is denied and the process proceeds to step 112. In step 112, the CPU 32 determines whether or not a predetermined time (a time clearly larger than one combustion cycle) has elapsed since the last selection of the rich combustion cylinder. If the determination in step 112 is denied, the dither control cylinder selection process ends.

If the determination in step 112 is affirmed, the process proceeds to step 114, and in step 114, the CPU 32 switches the rich combustion cylinder. The switching of the rich combustion cylinder in this step 114 is, for example, a predetermined pattern of switching the rich combustion cylinder (for example, the pattern of switching the rich combustion cylinder in the order of cylinder # 1, cylinder # 4, cylinder # 3, cylinder # 2). ) Can be done. When the process of step 110 is performed, the dither control cylinder selection process ends.

In the dither control according to the warm-up request of the three-way catalyst 24 or the execution request of the sulfur poisoning recovery treatment, the time cycle for switching the rich combustion cylinder is longer than that when the execution request of the filter regeneration processing is generated. The reason is as follows. That is, when the warm-up request of the three-way catalyst 24 is generated, and when the execution request of the sulfur poisoning recovery treatment of the three-way catalyst 24 is generated, the injection is performed as compared with the case where the execution request of the filter regeneration processing is generated. The amount correction request value α is set to a small value. As a result, when the warm-up request for the three-way catalyst 24 is generated, and when the execution request for the sulfur poisoning recovery treatment of the three-way catalyst 24 is generated, the internal combustion engine is compared with the case where the execution request for the filter regeneration processing is generated. This is because the torque fluctuation of the engine 10 becomes small.

Next, with reference to FIG. 4, another example of the dither control cylinder selection process M29 will be described only in a portion different from FIG. In the dither control cylinder selection process M29 shown in FIG. 4, a rich combustion cylinder is selected by the process of step 120 instead of steps 106 and 108 shown in FIG.

That is, in the dither control cylinder selection process M29 shown in FIG. 4, a switching pattern of the rich combustion cylinders is created in advance using random numbers so that the rich combustion cylinders are switched in a pattern according to random numbers. Then, in step 106, the CPU 32 selects a rich combustion cylinder based on the switching pattern. As a result, it is possible to switch the rich combustion cylinders in a pattern according to random numbers without generating random numbers.

As described above, in the present embodiment, at least a part of the plurality of cylinders of the internal combustion engine 10 has a theoretical air-fuel ratio when the regeneration process of the GPF 26 provided on the exhaust side of the internal combustion engine 10 is required. Dither control is performed so that the rich combustion cylinder is richer than the engine and the rest is the lean combustion cylinder leaner than the stoichiometric air-fuel ratio. Further, during the dither control, the cylinder to be the rich combustion cylinder among the plurality of cylinders is switched at random or in a pattern according to random. As a result, the torque fluctuation of the internal combustion engine 10 is dispersed to various orders, so that the occupant or the like senses the torque fluctuation caused by making the fuel injection amount to each cylinder non-uniform during the dither control. It can be suppressed from being done.

In the above, the mode of switching the rich combustion cylinder for each combustion cycle has been described, but the present disclosure is not limited to this, and the rich combustion cylinder is provided for each N combustion cycle (however, an integer of N> 1). You may switch.

Further, in the above, when the dither control is executed in response to the execution request of the filter regeneration process, the mode of switching the cylinder to be the rich combustion cylinder in a random or random pattern has been described. However, the present disclosure is not limited to this, and even when the dither control is executed in response to the warm-up request of the three-way catalyst 24 or the execution request of the sulfur poisoning recovery treatment, the cylinder to be a rich combustion cylinder is used. , Random or random patterns may be used.

Further, in the above, the upstream exhaust purification device is a three-way catalyst 24 and the downstream exhaust purification device is a GPF 26, but the present disclosure is not limited to this. For example, the upstream exhaust purification device may be a GPF and the downstream exhaust purification device may be a three-way catalyst. Further, for example, only GPF 26 may be provided. However, when a catalyst having an oxygen storage capacity is not provided upstream of the GPF, it is desirable to impart the oxygen storage capacity to the GPF in order to increase the temperature rising capacity by dither control.

Further, although the 4-cylinder internal combustion engine has been described above as the internal combustion engine 10, the present disclosure is not limited to this. For example, an in-line 6-cylinder internal combustion engine may be used, or a cylinder having a first exhaust gas purification device and a second exhaust gas purification device, such as a V-type internal combustion engine, and whose exhaust gas is purified by each. It may be different.

Further, in the above description, the embodiment in which the number of lean combustion cylinders is larger than the number of rich combustion cylinders has been described, but the present disclosure is not limited to this, and for example, the number of rich combustion cylinders and the number of lean combustion cylinders. May be the same as the number

Further, although the mode in which the control program 35 is stored (installed) in advance in the ROM 34 has been described above, the control program 35 is recorded in a non-temporary recording medium such as an HDD, SSD, or DVD. It is also possible to provide.

Next, the experiments carried out by the inventors of the present application will be described. This experiment includes the first experiment to the third experiment.

In the first experiment, the torque of the internal combustion engine is fluctuated as an input to the power train to be tested including the internal combustion engine, and the rotation fluctuation of the flywheel, the torque fluctuation of the input shaft, and the torque fluctuation of the drive shaft are changed. It was measured. FIG. 5 shows the vibration transmission sensitivity characteristics at each response point obtained in the first experiment. As is clear from FIG. 5, in the power train to be tested, resonance occurs at each response point at each frequency of 8.7 [Hz], 12.8 [Hz], and 17.1 [Hz]. ..

In the second experiment, the conventional dither control, that is, the dither control that keeps the rich combustion cylinder constant over multiple combustion cycles, is applied to the internal combustion engine of the power train to be tested, and the torque, rotation speed, and input of the internal combustion engine are applied. The shaft torque and the drive shaft torque were measured over a predetermined period of time. Then, FFT (Fast Fourier Transform) analysis is applied to the time-series data of the torque of the internal combustion engine, the number of revolutions, the torque of the input shaft, and the torque of the drive shaft obtained by this measurement, and the analysis / examination in the frequency domain is applied. Was done. The results of the second experiment are shown in FIG.

As is clear from FIG. 6, when the conventional dither control is performed, the torque of the internal combustion engine has a variation of 0.5th order of rotation. Further, this torque fluctuation of 0.5th order of rotation excites the resonance of the flywheel, the input shaft and the drive shaft, and the torque of the internal combustion engine, the torque of the input shaft and the torque of the drive shaft are 12.8 [Hz]. The variable component is very large.

Further, the third experiment is the second experiment except that the dither control according to the present disclosure, that is, the dither control for switching the rich combustion cylinder in each combustion cycle is applied to the internal combustion engine of the power train to be tested. Is the same as. The results of the third experiment are shown in FIG.

As is clear from FIG. 7, when the dither control according to the present disclosure is performed, the timing at which combustion occurs in the rich combustion cylinder, that is, the timing at which the torque of the internal combustion engine increases, is randomly changed, which is caused by the dither control. Torque fluctuations are distributed to various orders. Therefore, in the frequency characteristic of the torque of the internal combustion engine, the torque fluctuation component of the 0.5th order of rotation is suppressed. Further, since the torque fluctuation component of the 0.5th order of the torque rotation of the internal combustion engine is suppressed, the resonance of the flywheel, the input shaft and the drive shaft is not excited, and the rotation speed of the internal combustion engine, the torque of the input shaft and the torque of the input shaft are suppressed. Fluctuations in the torque of the drive shaft are suppressed.

10 Internal combustion engine 18 Fuel injection valve 24 Three-way catalyst 26 GPF (filter)
30 Control device 32 CPU
35 Control program

Claims (1)

At least, when the regeneration process of the filter provided on the exhaust side of the internal combustion engine is required, a part of the plurality of cylinders of the internal combustion engine is made into a rich combustion cylinder which is richer than the stoichiometric air-fuel ratio, and the rest is made. While performing dither control to make the lean combustion cylinder leaner than the stoichiometric air-fuel ratio, during the execution of the dither control, the cylinder to be the rich combustion cylinder among the plurality of cylinders is randomly or a pattern according to random. A control device for an internal combustion engine including a control unit for switching.

Images