JP6852425B2 - Internal combustion engine equipment - Google Patents

Description

The present invention relates to an internal combustion engine device, and more particularly to an internal combustion engine device including an internal combustion engine and a control device.

Conventionally, as an internal combustion engine device of this type, a device including a multi-cylinder internal combustion engine has been proposed (see, for example, Patent Document 1). In this device, the internal combustion engine is controlled so that the air-fuel ratio repeats rich or lean for each cylinder, the air-fuel ratio of each cylinder is estimated based on the output value of the air-fuel ratio sensor, and the air-fuel ratio is estimated based on the estimation result. The presence or absence of abnormality in each cylinder is determined. Further, as this type of internal combustion engine device, a device for determining whether or not an abnormality has occurred in each cylinder by using the rotation fluctuation of the internal combustion engine has been proposed (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2008-128080 Japanese Patent No. 5099216

In the above-mentioned internal combustion engine device, when the internal combustion engine is controlled so that the air-fuel ratio is repeatedly rich or lean for each cylinder, the rotation of the internal combustion engine fluctuates. When determining whether or not an abnormality has occurred in each cylinder using the rotational fluctuation of the internal combustion engine, if the air-fuel ratio is made rich or lean for each cylinder, there is no abnormality in each cylinder. However, the rotational fluctuation of the internal combustion engine becomes large, and it may be erroneously determined that an abnormality has occurred in the cylinder.

The main object of the internal combustion engine device of the present invention is to suppress erroneous determination when determining an abnormality in each cylinder of an internal combustion engine.

The internal combustion engine device of the present invention has adopted the following means in order to achieve the above-mentioned main object.

The internal combustion engine device of the present invention
With a multi-cylinder internal combustion engine
When the abnormality determination condition is satisfied, an abnormality determination is executed to determine whether or not an abnormality has occurred in each cylinder based on the rotation fluctuation of the internal combustion engine for each cylinder, and the dither control condition is satisfied. When there is, a control device that executes dither control that controls the internal combustion engine so that the air-fuel ratio repeats rich and lean for each cylinder.
It is an internal combustion engine device equipped with
The control device determines that the abnormality has occurred in at least one cylinder when the rotation fluctuation is equal to or greater than the determination threshold value.
Further, when the abnormality determination condition is satisfied and the dither control condition is satisfied, the control device increases the determination threshold value as compared with the case where the dither control condition is not satisfied.
The gist is that.

In the internal combustion engine device of the present invention, when the abnormality determination condition is satisfied, an abnormality determination is executed to determine whether or not an abnormality has occurred in each cylinder based on the rotation fluctuation of the internal combustion engine for each cylinder. When the dither control condition is satisfied, dither control is executed to control the internal combustion engine so that the air-fuel ratio repeats rich and lean for each cylinder. The abnormality determination determines that an abnormality has occurred in the cylinder when the rotation fluctuation is equal to or higher than the determination threshold value in at least one cylinder. Further, when the abnormality determination condition is satisfied and the dither control condition is satisfied, the determination threshold value is increased as compared with the case where the dither control condition is not satisfied. When the dither control condition is satisfied, the dither control is executed, and the rotation fluctuation of the internal combustion engine becomes large even when each cylinder is normal. Therefore, it may be erroneously determined that the abnormality determination is executed using the same determination threshold value regardless of whether or not the dither control is executed. However, the abnormality determination condition is satisfied and the dither control condition is satisfied. When the dither control condition is satisfied, the determination threshold value is made larger than when the dither control condition is not satisfied, so that it is possible to suppress erroneous determination when determining an abnormality in each cylinder of the internal combustion engine. Here, the "determination threshold value" is a threshold value for determining whether or not an abnormality has occurred in each cylinder when the dither control is being executed, and is an internal combustion engine when the dither control is being executed. It is a value set based on the rotation fluctuation of the internal combustion engine and the rotation fluctuation of the internal combustion engine when an abnormality occurs in each cylinder.

In such an internal combustion engine device of the present invention, the control device controls the dither when the abnormality determination condition is satisfied and the dither control condition is satisfied and the dither ratio is equal to or higher than a predetermined value. The determination threshold value may be made larger than when the condition is not satisfied. Here, the "dither rate" is the ratio of the increase value obtained by subtracting the cylinder average injection amount from the actual fuel injection amount of the rich cylinder to the cylinder average injection amount obtained by dividing the fuel injection amount of the entire internal combustion engine by the number of cylinders. Or the sum of the ratio of the reduction value obtained by subtracting the actual fuel injection amount from the cylinder average injection amount of the lean cylinder to the cylinder average injection amount. The "predetermined value" is a threshold value for determining whether or not the dither rate is a value at which an erroneous determination is likely to occur in the abnormality determination. When the dither rate is equal to or more than a predetermined value, the rotation fluctuation of the internal combustion engine becomes larger than when the dither rate is less than the predetermined value, so that it is easy to make an erroneous determination of an abnormality. Therefore, when the abnormality judgment condition is satisfied and the dither control condition is satisfied, the judgment threshold value is set when the dither rate is equal to or higher than the predetermined value and when the dither control condition is not satisfied. By increasing the value, it is possible to suppress an erroneous determination in the abnormality determination.

Further, in the internal combustion engine device of the present invention, the control device is abnormal with respect to a cylinder leaning in dither control when the abnormality determination condition is satisfied and the dither control condition is satisfied. When executing the determination, the determination threshold value may be made larger than when the dither control condition is not satisfied. The rotation fluctuation when the lean cylinder in the dither control is ignited is larger than the rotation fluctuation when the cylinder rich in the dither control is ignited. Therefore, in the abnormality determination in the lean cylinder, it is easy to make an erroneous determination. Therefore, when the abnormality determination condition is satisfied and the dither control condition is satisfied, the dither control condition is not satisfied when the abnormality determination is executed for the cylinder leaning in the dither control. By increasing the determination threshold value as compared with the case, it is possible to suppress erroneous determination in the abnormality determination.

Further, in the internal combustion engine device of the present invention, the internal combustion engine may be equipped with a purification device having a purification catalyst for purifying the exhaust gas in the exhaust system, or a filter for removing particulate matter is attached to the exhaust system. May be.

Then, in the internal combustion engine device of the present invention, the abnormality determination determines that each cylinder of the internal combustion engine has a misfire as the abnormality, or the fuel injection amount between the cylinders is imbalanced. This may be determined as the abnormality.

It is a block diagram which shows the outline of the structure of the internal combustion engine device 20 as one Example of this invention. It is a flowchart which shows an example of the misfire determination routine executed by the ECU 24. It is explanatory drawing which shows an example of the time change of the rotation fluctuation amount Δω of an engine 22 when a misfire does not occur. It is a flowchart which shows an example of the misfire determination routine of a modification. It is explanatory drawing which shows an example of the time change of the rotation fluctuation amount Δω of an engine 22 when a misfire does not occur in the internal combustion engine apparatus of a modification. It is a flowchart which shows an example of the imbalance determination routine when the present invention is applied to imbalance determination. It is a flowchart which shows an example of the imbalance determination routine of a modification.

Next, a mode for carrying out the present invention will be described with reference to examples.

FIG. 1 is a configuration diagram showing an outline of the configuration of an internal combustion engine device 20 as an embodiment of the present invention. As shown in the figure, the internal combustion engine device 20 of the embodiment includes an engine 22 and an electronic control unit (hereinafter, referred to as “ECU”) 24. The internal combustion engine device 20 is mounted on a hybrid vehicle together with, for example, a traveling motor.

The engine 22 is configured as a multi-cylinder internal combustion engine that outputs power by each stroke of intake, compression, expansion (explosion combustion), and exhaust using a hydrocarbon-based fuel such as gasoline or light oil. The engine 22 sucks the air cleaned by the air cleaner 122 into the intake pipe 125 via the throttle valve 124, and injects fuel from the fuel injection valve 126 to mix the air and the fuel. Then, this air-fuel mixture is sucked into the combustion chamber 129 via the intake valve 128a, explosively burned by an electric spark from the spark plug 130, and the reciprocating motion of the piston 132 pushed down by the energy is converted into the rotational motion of the crankshaft 26. To do. The exhaust gas discharged from the combustion chamber 129 to the exhaust pipe 133 via the exhaust valve 128b is a purification catalyst (three elements) that purifies harmful components of carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). It is discharged to the outside air through an exhaust gas purification device 134 having a catalyst) and a particulate matter removal filter (hereinafter referred to as PM filter) 25. The exhaust gas purification device 134 is filled with a catalyst for removing unburned fuel and nitrogen oxides in the exhaust gas. The PM filter 25 is formed of ceramics, stainless steel, or the like as a porous filter, and captures particulate matter (PM: Particulate Matter) such as soot. The engine 22 includes variable valve timing mechanisms 150a and 150b that can change the opening / closing timing of the intake valve 128a and the exhaust valve 128b. The operation of the engine 22 is controlled by the ECU 24.

Although not shown, the ECU 24 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU.

Signals from various sensors necessary for controlling the operation of the engine 22 are input to the ECU 24 via the input port. As signals input to the ECU 24, for example, a crank angle θcr from the crank position sensor 140 that detects the rotational position of the crankshaft 26 and a cooling water temperature Tw from the water temperature sensor 142 that detects the temperature of the cooling water of the engine 22. Can be mentioned. Further, the cam angles θca and θcb from the cam position sensors 144a and 144b that detect the rotation position of the intake camshaft that opens and closes the intake valve 128a and the rotation position of the exhaust camshaft that opens and closes the exhaust valve 128b can also be mentioned. Further, the throttle opening TH from the throttle valve position sensor 146 that detects the position of the throttle valve 124, the intake air amount Qa from the air flow meter 148 attached to the intake pipe, and the temperature sensor 149 attached to the intake pipe The intake air temperature Ta can also be mentioned. The injection pressure Pinj from the pressure sensor 126a, which is attached to the inside of the fuel injection valve 126 of each cylinder and detects the pressure of the injected fuel, can also be mentioned. The air-fuel ratio AF from the air-fuel ratio sensor 135a attached to the exhaust pipe and the oxygen signal O2 from the oxygen sensor 135b attached to the exhaust pipe can also be mentioned. Further, the pressures P1 and P2 from the pressure sensors 25a and 25b attached to the upstream side and the downstream side of the PM filter 25 can also be mentioned.

Various control signals for controlling the operation of the engine 22 are output from the ECU 24 via the output port. The signals output from the ECU 24 include, for example, a drive control signal to the throttle motor 136 that adjusts the position of the throttle valve 124, a drive control signal to the fuel injection valve 126, and an ignition coil 138 integrated with the igniter. The drive control signal and the drive control signal to the variable valve timing mechanisms 150a and 150b can also be mentioned.

The ECU 24 calculates the rotation speed of the crankshaft 26, that is, the rotation speed Ne of the engine 22, based on the crank angle θcr. Further, the ECU 24 calculates the actual fuel injection amount (actual injection amount) Pil for each cylinder from the pressure waveform (time change of pressure) of the injection pressure Pinj from the pressure sensor 126a of each cylinder. The ECU 24 is based on the volumetric efficiency (the ratio of the volume of air actually sucked in one cycle to the stroke volume of the engine 22 per cycle) based on the intake air amount Qa from the air flow meter 148 and the rotation speed Ne of the engine 22. ) KL is also calculated. The ECU 24 has a PM deposition amount Qpm as an estimated deposition amount of particulate matter supplemented to the PM filter 25 based on the differential pressure ΔP (ΔP = P1-P2) of the pressures P1 and P2 from the pressure sensors 25a and 25b. Or, the filter temperature Tf as the estimated temperature of the PM filter 25 is calculated based on the operating state of the engine 22. Further, the ECU 24 takes 30 degrees, which is the time required for the crankshaft 26 to rotate by 30 degrees each time the crankshaft 26 rotates by a predetermined angle (for example, 10 degrees) based on the crank angle θcr. T30 (msec) is acquired, and the angular velocity ωeg (rad / sec) of the crankshaft 26 (engine 22) is calculated based on the 30-degree rotation time required T30. The angular velocity ωeg is calculated as ωeg = 2π × (30/360) / T30 × 1000.

In the internal combustion engine device 20 of the embodiment configured in this way, the ECU 24 controls the intake air amount that adjusts the opening degree of the throttle valve 124 so that the required output is output from the engine 22, and fuel injection from the fuel injection valve 126. Fuel injection control for adjusting the amount, ignition control for adjusting the ignition timing of the spark plug 130, and the like are performed.

Next, the operation of the internal combustion engine device 20 of the embodiment configured in this way, particularly the operation when determining whether or not a misfire has occurred in the engine 22 will be described. FIG. 2 is a flowchart showing an example of a misfire determination routine executed by the ECU 24. This routine is repeatedly executed while the engine 22 is running.

When this routine is executed, the ECU 24 executes a process of inputting the rotation speed Ne of the engine 22, the volumetric efficiency KL, the dither control flag F, and the actual injection amount Pil of each cylinder (step S100). Here, the rotation speed Ne of the engine 22 is input calculated based on the crank angle θcr. The volumetric efficiency KL is calculated based on the intake air amount Qa from the air flow meter 148 and the rotation speed Ne of the engine 22. The dither control request flag F is set to a value 0 when the execution of the dither control is not requested, and a flag set to the value 1 when the execution of the dither control is requested is input. The actual injection amount Pil is input calculated based on the injection pressure Pinj from the pressure sensor 126a.

Here, dither control will be described. In the dither control, the fuel is repeatedly adjusted so that the air-fuel ratio of the engine 22 is rich (a state in which the amount of fuel is increased compared to the theoretical air-fuel ratio) and lean (a state in which the amount of fuel is reduced compared to the theoretical air-fuel ratio). It is a control that injects and operates the engine 22. In this dither control, some of the plurality of cylinders of the engine 22 are enriched, the remaining cylinders are lean, the dither rate is set to the target value Rdc, and the average value of increase / decrease in the fuel injection amount of the engine 22 as a whole is set. The engine 22 is operated so that the value becomes 0. The dither rate is the sum of the ratio of the increase value obtained by subtracting the cylinder average injection amount from the actual fuel injection amount of the rich cylinder to the cylinder average injection amount obtained by dividing the fuel injection amount of the engine 22 by the number of cylinders. For example, when the engine 22 is a 6-cylinder internal combustion engine and the dither rate is 0.2 (20%), the fuel injection amount of each cylinder is the fuel injection amount of the cylinder that ignites first with respect to the cylinder average injection amount. The amount is reduced by 5%, the fuel injection amount of the next ignited cylinder is increased by 10% with respect to the average cylinder injection amount, and the fuel injection amount of the remaining cylinders is reduced by 5% in the order of ignition thereafter. The engine 22 is operated as lean, lean of 5%, rich of 10%, and lean of 5%. Then, when the engine 22 rotates at a predetermined rotation Nref (for example, 100 rotations, 200 rotations, 300 rotations, etc.), the cylinder to be rich and the cylinder to be lean are changed. For example, the fuel injection amount of the first ignited cylinder is set to be 10% richer than the average cylinder injection amount, and the fuel injection amount of the remaining cylinders is set to lean by 5% and rich by 10% in the order of ignition thereafter. The engine 22 is operated as a lean of 5% reduction, a lean of 5% reduction, and a lean of 5% reduction. The reason for changing the rich cylinder and the lean cylinder in this way is that if some cylinders are continuously enriched, the rich cylinders deteriorate faster than the other cylinders. By such control, the exhaust temperature is raised to purge the sulfur content poisoned in the purification catalyst of the exhaust purification device 134, and the temperature of the PM filter 25 is quickly raised to a reproducible temperature (for example, 600 ° C.) or higher. Raise it to regenerate the PM filter 25.

Such dither control is performed by the first condition in which the PM filter 25 is requested to be regenerated, the second condition in which the engine 22 is operating (the engine 22 is not stopped or the fuel is not cut), and the engine 22 is empty. The third condition that the fuel ratio is stable (the feedback correction amount in the air-fuel ratio control of the engine 22 is within a predetermined range and the learning about the air-fuel ratio is completed) and the warm-up of the engine 22 are completed (the engine 22 is warmed up). The execution request is made when all the conditions of the fourth condition that the cooling water temperature Tw of the engine 22 is equal to or higher than a predetermined temperature (for example, 70 ° C., 75 ° C., 80 ° C., etc.) are satisfied. The regeneration request of the PM filter 25 is made when the PM accumulation amount Qpm as the accumulation amount of the particulate matter deposited on the PM filter 25 is equal to or more than the threshold value Qpmref. Here, the PM accumulation amount Qpm is calculated (estimated) based on the differential pressure ΔP (ΔP = P1-P2) of the pressures P1 and P2 from the pressure sensors 25a and 25b. The threshold value Qpmref is a PM accumulation amount Qpm that can be determined to require regeneration of the PM filter 25. The dither control request flag F is set to a value 0 when at least one of the above-mentioned first to fourth conditions is not satisfied, and all the first to fourth conditions are satisfied. Sometimes it is set to a value of 1.

Subsequently, it is determined whether or not the misfire determination condition is satisfied (step S110). Here, the first determination condition or volume in which the rotation speed Ne of the engine 22 is higher than the lower limit rotation speed Nmin (for example, 800 rpm, 850 rpm, 900 rpm, etc.) and lower than the upper limit rotation speed Nmax (for example, 6000 rpm, 6500 rpm, 7000 rpm, etc.) or volume. When the second determination condition in which the efficiency KL is equal to or higher than the predetermined rate Kref (for example, 9.0%, 9.5%, 10%, etc.) is satisfied, it is determined that the misfire determination condition is satisfied.

When it is determined in the process of step S110 that the misfire determination condition is not satisfied, it is determined that it is not necessary to execute the misfire determination, and this routine is terminated.

When it is determined in the process of step S110 that the misfire determination requirement is satisfied, it is subsequently determined whether or not the dither control flag F has a value of 1 (step S120). When the dither control flag F has a value of 0, the dither control is not executed. Therefore, the misfire determination is executed with the determination threshold value dωref as the predetermined value dωref1 (step S170), and this routine is terminated. In the misfire determination, first, when the ignition timing arrives for each combustion chamber, the rotational fluctuation amount Δω of the engine 22 is calculated based on the angular velocity ωeg calculated at that time and the angular velocity ωeg at the previous ignition timing of the combustion chamber. Then, the rotation fluctuation amount Δω and the determination threshold dωref are compared. Here, the determination threshold value dωref is a threshold value for determining whether or not a misfire has occurred in the combustion chamber. Then, when the rotation fluctuation amount Δω is equal to or higher than the determination threshold dωref, it is determined that the rotation fluctuation amount Δω may be increased due to the occurrence of misfire in the combustion chamber, and subsequently, the rotation fluctuation amount is determined to be large. The time waveform of Δω is compared with the predetermined determination waveform. Then, when the time waveform of the rotation fluctuation amount Δω is the same as the judgment waveform within the error range, it is determined that no misfire has occurred, and the time waveform of the rotation fluctuation amount Δω is within the error range of the judgment waveform. When it becomes larger than that, it is determined that a misfire has occurred. By such a determination, it can be determined whether or not a misfire has occurred. The predetermined value dωref1 is slightly larger than the maximum value of the rotation fluctuation amount Δω of the engine 22 when the dither control is not executed and when the dither rate follows the target value Rdc in the case where no misfire has occurred. The value is set in advance by experiment or analysis.

When it is determined in the process of step S120 that the dither control flag F has a value of 1, the actual dither rate Rdr is set using the input actual injection amount Pir of each cylinder (step S130). The actual dither rate Rdr is the ratio of the increase value obtained by subtracting the actual cylinder average injection amount from the rich cylinder actual injection amount Pil to the actual cylinder average injection amount obtained by dividing the sum of the actual injection amount Pil of each cylinder by the number of cylinders. It is the sum. For example, the actual fuel injection amount Pil of the cylinder that ignites first is lean by 5.2% less than the average injection amount of the actual cylinder of the engine 22 during the predetermined rotation Nref, and then increases by 10.3% in the order of ignition. The actual dither rate Rdr is 0.204 (when it is rich, 5.1% reduced lean, 5.1% decreased lean, 10.1% increased rich, and 5.0% decreased lean. = 0.103 (10.3%) + 0.101 (10.1%)). The actual dither rate Rdr may be the sum of the ratios of the reduction amounts obtained by subtracting the actual injection amount Pil of the lean cylinder from the actual cylinder average injection amount to the actual cylinder average injection amount.

Subsequently, it is determined whether or not the actual dither rate Rdr is equal to or greater than the determination threshold value Rdref (step S140). The determination threshold value Rdref is a value predetermined as a dither rate at which the rotation fluctuation amount Δω of the engine 22 due to dither control exceeds a predetermined value dωref1 even though no misfire has occurred, and is a value larger than the target value Rdc. Is set to. Even if the dither control is executed so that the dither rate becomes the target value Rdc, the actual dither rate (actual dither rate Rdr) becomes large due to the control error, and the rotation fluctuation amount Δω of the engine 22 becomes the predetermined value dωref1 or more. , Misjudgment may occur in misfire judgment. The process of step S140 is a process of determining whether or not such an erroneous determination may occur.

When it is determined in the process of step S140 that the actual dither rate Rdr is less than the determination threshold value Rdreff, it is determined that a misfire determination may be made using the predetermined value dωref1 as the determination threshold value dωref, and the process of step S170. The misfire determination is executed using the predetermined value dωref1 as the determination threshold value dωref1 (step S170), and this routine is terminated.

When it is determined in the process of step S140 that the actual dither coefficient Rdr is equal to or greater than the determination threshold value Rdreff, it is determined that there is a possibility of erroneous determination that the misfire determination is executed using the predetermined value dωref1 as the determination threshold value dωref. The increase coefficient k is set using the actual dither rate Rdr (step S150), the determination threshold dωref is increased using the increase coefficient k (step S160), and the determination threshold dωref increased in the process of step S160. The misfire determination is executed using (step S170), and this routine is terminated. In the process of step S150, the pull-up coefficient k erroneously determines the misfire even if the actual dither rate (actual dither rate Rdr) becomes larger than the target value Rdc due to the control error and the rotation fluctuation amount Δω of the engine 22 becomes large. It is a coefficient for adjusting the determination threshold value dωref so as not to be performed, and is set as a value larger than the value 1. When the actual dither ratio Rdr is large, the rotation fluctuation amount Δω of the engine 22 is larger than when it is small. That is, the larger the actual dither ratio Rdr is, the larger the rotation fluctuation amount Δω of the engine 22 is. However, when the actual dither ratio Rdr is large, it is set to be larger than when it is small, that is, it is set so that it becomes larger as the actual dither ratio Rdr is larger. By such processing, the determination threshold value dωref is set larger than when the dither control flag F has a value of 0.

FIG. 3 is an explanatory diagram showing an example of a time change of the rotational fluctuation amount Δω of the engine 22 when no misfire has occurred. In the figure, the solid line shows the rotation fluctuation amount Δω when the dither control is executed, and the judgment threshold dωref (when the dither control is executed and the actual dither rate Rdr is equal to or higher than the judgment threshold Rdreff). An example of time change with = k · dωref1) is shown. The broken line shows an example of the time change between the rotation fluctuation amount Δω and the determination threshold value dωref (= dωref1) when the dither control is not executed. In dither control, the engine 22 is operated by injecting fuel so that the air-fuel ratio of the engine 22 is rich or lean for each cylinder. Therefore, as shown in the figure, the engine 22 undergoes rotational fluctuation. In the dither control, when the actual dither rate Rdr follows the target value Rdc when no misfire has occurred, the rotational fluctuation amount Δω is less than the predetermined value dωref1 as shown in the figure. It is determined that no misfire has occurred. However, when the actual dither rate Rdr deviates from the target value Rdc in the direction of increasing and becomes equal to or greater than the determination threshold value Rdreff, the rotational fluctuation amount Δω may exceed the predetermined value dωref1. In the embodiment, when the actual dither rate Rdr is equal to or higher than the determination threshold value Rdreff, the determination threshold value dωref is set to a value larger than the predetermined value dωref1 (k · dωref), so that erroneous determination of misfire can be suppressed.

According to the internal combustion engine device 20 of the embodiment described above, when the misfire determination condition is satisfied and the dither control flag F is a value 1, the actual dither ratio Rdr is equal to or greater than the determination threshold value Rdreff. By setting the determination threshold value dωref to be larger than when the dither control flag F has a value of 0, it is possible to suppress erroneous determination in the misfire determination.

In the internal combustion engine device 20 of the embodiment, when the actual dither rate Rdr is equal to or higher than the determination threshold value Rdrf in the processes of steps S140 to S160, the pull-up coefficient k is set using the actual dither rate Rdr, and the coefficient k is set to a predetermined value. The value multiplied by the value dωref1 is set as the determination threshold value dωref. However, as shown in an example of the misfire determination routine of the modified example of FIG. 4, whether or not the process of step S200 is executed instead of the process of step S140 and the misfire determination is executed for the lean cylinder. When performing a misfire determination for a lean cylinder, the pull-up coefficient k is set using the actual dither rate Rdr, and the coefficient k multiplied by the predetermined value dωref1 is the determination threshold value dωref. May be set to.

FIG. 5 is an explanatory diagram showing an example of a time change of the rotation fluctuation amount Δω of the engine 22 when a misfire does not occur in the internal combustion engine device of the modified example. In the figure, the solid line shows an example of the time change between the rotation fluctuation amount Δω and the determination threshold value dωref (= k · dωref1) when the dither control is executed. The broken line shows an example of the time change between the rotation fluctuation amount Δω and the determination threshold value dωref (= dωref1) when the dither control is not executed. The amount of rotational fluctuation Δω of the engine 22 when igniting a lean cylinder is larger than when igniting a rich cylinder. Therefore, when determining whether or not a lean cylinder has a misfire, a misjudgment of misfire occurs as compared with when determining whether or not a rich cylinder has a misfire. Cheap. In the modified example, as shown in the figure, when determining a misfire of a lean cylinder, a pull-up coefficient k is set using the actual dither rate Rdr, and the coefficient k multiplied by a predetermined value dωref1 is used as a determination threshold value. Set to dωref. In this way, it is possible to suppress erroneous determination in the determination of misfire.

In the internal combustion engine device 20 of the embodiment, in the process of step S160, the determination threshold dωref is raised by setting the determination threshold dωref by multiplying the predetermined value dωref1 by a coefficient k larger than the value 1. However, since the determination threshold value dωref may be set to a value larger than the predetermined value dωref1, the determination threshold value dωref may be set to, for example, a predetermined value dωref2 larger than the predetermined value dωref1.

In the internal combustion engine device 20 of the embodiment, when the dither control flag F is determined to have a value of 1 in the process of step S120, the actual dither coefficient Rdr is equal to or greater than the determination threshold value Rdrf in the processes of steps S130 to S160. The pull-up coefficient k is set using the actual dither rate Rdr, and the coefficient k multiplied by the predetermined value dωref1 is set as the determination threshold value dωref. However, when it is determined in the process of step S120 that the dither control flag F has a value of 1, the process of steps S130, S150, and S160 may be executed without executing the process of step S140.

In the internal combustion engine device 20 of the embodiment, a case where the present invention is applied to a process of determining a misfire has been described. However, since the present invention may be applied to an abnormality determination process using the rotation fluctuation amount Δω of the engine 22, for example, an imbalance determination for determining whether or not an imbalance of fuel injection amount between cylinders has occurred. It may be applied to the processing of. FIG. 6 is a flowchart showing an example of an imbalance determination routine when the present invention is applied to imbalance determination. The processing executed by this routine is a point at which the processing of steps S310 and S370 is executed instead of the processing of steps S110 and S170 of the misfire determination routine illustrated in FIG. The process is the same as that of the misfire determination routine illustrated in FIG. Therefore, the same processing is designated by the same reference numerals, and detailed description thereof will be omitted.

When the process of inputting necessary data is executed in the process of step S100, it is determined in the process of step S310 whether or not the imbalance determination condition is satisfied (step S310). The imbalance determination condition is a precondition for executing the imbalance determination, and is determined to be satisfied when the cooling water temperature Tw is equal to or higher than the threshold value Twref. The threshold value Tweet is a threshold value used for determining whether or not the warm-up of the engine 22 is completed, and for example, 70 ° C., 75 ° C., 80 ° C. and the like can be used.

When it is determined in the process of step S310 that the imbalance determination condition is not satisfied, this routine is terminated.

When it is determined in the process of step S310 that the imbalance determination condition is satisfied, it is determined whether or not the dither control flag F has a value of 1 (step S120), and the dither control flag F has a value of 0. Occasionally, the imbalance determination is executed (step S370) to end this routine. Here, the imbalance determination is a process of determining whether or not the fuel injection amount is imbalanced between the cylinders. The imbalance of fuel injection amount between cylinders is rich imbalance in which the fuel injection amount of one cylinder is larger than the fuel injection amount of the other cylinder, and the fuel injection amount of one cylinder is the other. There is a lean imbalance that is less than the fuel injection amount of the cylinder. In the imbalance determination of the embodiment, when the ignition timing arrives for each combustion chamber, the rotational fluctuation amount Δω of the engine 22 is based on the angular velocity ωeg calculated at that time and the angular velocity ωeg at the previous ignition timing of the combustion chamber. Is calculated, and the rotation fluctuation amount Δω is compared with the determination threshold dωref. Here, the determination threshold value dωref is set to a predetermined predetermined value dωref1. The predetermined value dωref1 is set in advance by experiments or analysis as a value slightly larger than the maximum value of the rotational fluctuation amount of the engine 22 when the dither control is not executed and when the dither rate follows the target value Rdc. There is. Then, when the rotational fluctuation amount Δω is equal to or greater than the determination threshold value dωref, it is determined that imbalance has occurred in the combustion chamber.

When it is determined in the process of step S120 that the dither control flag F has a value of 1, the actual dither rate Rdr is set using the input actual injection amount Pir (step S130), and the actual dither rate Rdr is determined. It is determined whether or not the threshold value is Rdref or higher (step S140). Then, when it is determined that the determination threshold value is less than the determination threshold value Rdreff, it is determined that the imbalance determination may be executed using the predetermined value dωref1 as the determination threshold value dωref, and the process proceeds to step S170 to proceed to the determination threshold value. Imbalance determination is executed using the predetermined value dωref1 as dωref (step S370), and the process ends. The dither control is a control that causes an imbalance in the fuel injection amount between cylinders, but the predetermined value dωref is set as a threshold value that can determine that the degree of imbalance in the dither control is exceeded. .. Therefore, the imbalance determination when the dither control flag F has a value of 1 is a process of determining whether or not an imbalance exceeding the degree of imbalance in the dither control has occurred.

When it is determined in the process of step S140 that the actual dither coefficient Rdr is equal to or greater than the determination threshold value Rdreff, it is determined that there is a possibility of erroneous determination if the imbalance determination is executed using the predetermined value dωref1 as the determination threshold value dωref1. , The pull-up coefficient k is set using the actual dither rate Rdr (step S150), the process of raising the judgment threshold value dωref is executed using the pull-up coefficient k (step S160), and the judgment threshold value raised in the process of step S160 is executed. The imbalance determination is executed using dωref (step S370), and this routine is terminated. In this way, even when the actual dither rate Rdr is larger than the target value Rdc, it is possible to suppress erroneous determination in the imbalance determination.

Further, when the present invention is applied to the imbalance determination, the imbalance determination routine of the modified example illustrated in FIG. 7 may be executed instead of the imbalance determination routine of the modified example illustrated in FIG. The imbalance determination routine of the modified example illustrated in FIG. 7 executes the processing of steps S310 and S370 described above instead of the processing of steps S110 and S170 of the misfire determination routine illustrated in FIG. 4, and the determination threshold value dωref. The process is the same as that of the misfire determination routine illustrated in FIG. 4, except that is a threshold value for determining imbalance. In this way, in the imbalance determination, the pull-up coefficient k is set using the actual dither rate Rdr when determining whether or not the lean cylinder has an imbalance that exceeds the degree of imbalance in the dither control. Then, the coefficient k multiplied by the predetermined value dωref1 may be set as the determination threshold value dωref. This is larger than when igniting a cylinder in which the rotation fluctuation amount Δω of the engine 22 when igniting a lean cylinder is rich, and whether or not an imbalance has occurred in the lean cylinder. This is because the imbalance determination is more likely to be erroneously determined when determining whether or not imbalance has occurred in the rich cylinder. In the modified example, when determining the imbalance of a lean cylinder, the pull-up coefficient k is set using the actual dither rate Rdr, and the coefficient k multiplied by the predetermined value dωref1 is set as the determination threshold value dωref. To do. In this way, it is possible to suppress an erroneous determination in the imbalance determination.

In the internal combustion engine device 20 of the embodiment, the dither control request flag F is set to a value 0 when at least one of the first to fourth conditions is not satisfied, and all of the first to fourth conditions are set. When the condition of is satisfied, the value is set to 1. However, since it is sufficient to set the value 1 when at least the first condition is satisfied, the value 1 may be set when the first to third conditions are satisfied without considering the fourth condition. , The value 1 may be set when the first and fourth conditions are satisfied without considering the second and third conditions. Further, the dither control request flag F may be set based on other conditions without being limited to the first to fourth conditions.

The correspondence between the main elements of the examples and the main elements of the invention described in the column of means for solving the problem will be described. In the embodiment, the engine 22 corresponds to the "internal combustion engine" and the ECU 24 corresponds to the "control device".

Regarding the correspondence between the main elements of the examples and the main elements of the invention described in the column of means for solving the problem, the invention described in the column of the means for solving the problem in the examples is carried out. Since it is an example for specifically explaining the form for solving the problem, the elements of the invention described in the column of means for solving the problem are not limited. That is, the interpretation of the invention described in the column of means for solving the problem should be performed based on the description in the column, and the examples are the inventions described in the column of means for solving the problem. It is just a concrete example.

Although the embodiments for carrying out the present invention have been described above with reference to examples, the present invention is not limited to these examples, and various embodiments are used without departing from the gist of the present invention. Of course, it can be done.

The present invention can be used in the manufacturing industry of internal combustion engine devices and the like.

20 Internal combustion engine equipment, 22 Engine, 24 Electronic control unit (ECU), 25 Particle substance removal filter (PM filter), 25a, 25b pressure sensor, 26 Crankshaft, 122 Air cleaner, 124 Throttle valve, 125 Intake pipe, 126 Fuel Injection valve, 126a pressure sensor, 128a intake valve, 128b exhaust valve, 129 combustion chamber, 130 ignition plug, 132 piston, 133 exhaust pipe, 134 exhaust purification device, 135a air fuel ratio sensor, 135b oxygen sensor, 136 throttle motor, 138 ignition Coil, 140 crank position sensor, 142 water temperature sensor, 144a, 144b cam position sensor, 146 throttle valve position sensor, 148 airflow meter, 149 temperature sensor, 150a, 150b variable valve timing mechanism.

Claims (1)

With a multi-cylinder internal combustion engine
When the abnormality determination condition is satisfied, an abnormality determination is executed to determine whether or not an abnormality has occurred in each cylinder based on the rotation fluctuation of the internal combustion engine for each cylinder, and the dither control condition is satisfied. When there is, a control device that executes dither control that controls the internal combustion engine so that the air-fuel ratio repeats rich and lean for each cylinder.
It is an internal combustion engine device equipped with
The control device determines that the abnormality has occurred in at least one cylinder when the rotation fluctuation is equal to or greater than the determination threshold value.
Further, the control device is rich with respect to the cylinder average injection amount obtained by dividing the fuel injection amount of the internal combustion engine by the number of cylinders when the abnormality determination condition is satisfied and the dither control condition is satisfied. The sum of the ratio of the increase value obtained by subtracting the cylinder average injection amount from the cylinder fuel injection amount or the sum of the ratio of the decrease amount obtained by subtracting the lean cylinder fuel injection amount from the cylinder average injection amount to the cylinder average injection amount. When the dither ratio is equal to or greater than a predetermined value, the determination threshold value is increased as compared with the case where the dither control condition is not satisfied.
Internal combustion engine device.

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