JP2024020903A - Engine device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration in emission when a scavenge rate is large.

SOLUTION: An engine device executes feed-forward control on the rich-lean balance of a catalyst atmosphere in engine exhaust gas by using a lean determination value and a rich determination value and by setting, as a targe air-fuel ratio, a first air-fuel ratio detected by a first air-fuel ratio sensor for detecting an air-fuel ratio of the exhaust gas supplied to an emission control device. At that time, according to a scavenging rate, the control is switched to feedback control of the rich-lean balance, in which the lean determination value and the rich determination value are used and a target air-fuel ratio is set to the first air-fuel ratio based on a second air-fuel ratio detected by a second air-fuel ratio sensor for detecting an air-fuel ratio of the exhaust gas discharged from the emission control device.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to an engine device.

Conventionally, this type of engine device sets the target air-fuel ratio alternately to a rich air-fuel ratio and a lean air-fuel ratio, and also sets the air-fuel ratio of exhaust gas so that the output air-fuel ratio of the air-fuel ratio sensor becomes the target air-fuel ratio. A control method has been proposed (for example, see Patent Document 1). In this engine device, when scavenging occurs, the degree of leanness of the target air-fuel ratio when the target air-fuel ratio is set to a lean air-fuel ratio is increased compared to when scavenging does not occur. The unburned gas is purified.

JP2017-057760A

In an engine device equipped with a particulate matter removal filter that removes particulate matter, if the amount of particulate matter deposited on the particulate matter removal filter increases, the back pressure of the engine exhaust will increase, and the estimated scavenge rate will increase. The scavenging rate becomes larger than the actual scavenging rate, and the amount of correction for making the air-fuel ratio stoichiometric becomes excessive. For this reason, unburned gas (HC) and incompletely combusted gas (CO) in the exhaust gas increase, and emissions may deteriorate.

The main purpose of the engine device of the present invention is to suppress deterioration of emissions when the scavenge rate is large.

The engine device of the present invention employs the following means to achieve the above-mentioned main purpose.

The engine device of the present invention includes:
An engine having a supercharger, a variable valve timing mechanism, a port injection valve, and an in-cylinder injection valve;
a purification device having a purification catalyst that purifies exhaust gas from the engine;
a first air-fuel ratio sensor that detects a first air-fuel ratio that is an air-fuel ratio of exhaust gas supplied to the purification device;
a second air-fuel ratio sensor that detects a second air-fuel ratio that is an air-fuel ratio of exhaust gas discharged from the purification device;
a particulate matter removal filter that removes particulate matter contained in exhaust from the engine;
A control device that performs feedforward control of the rich-lean balance of a catalyst atmosphere in the exhaust gas of the engine using a lean determination value and a rich determination value to make the first air-fuel ratio a target air-fuel ratio based on the first air-fuel ratio. ,
An engine device comprising:
The control device adjusts the rich/lean balance according to a scavenge rate to a first air-fuel ratio based on the second air-fuel ratio detected by the second air-fuel ratio sensor using the lean determination value and the rich determination value. Switch to feedback control with the target air-fuel ratio,
It is characterized by

The engine device of the present invention includes an engine having a supercharger, a variable valve timing mechanism, a port injection valve, and an in-cylinder injection valve, a purification device having a purification catalyst that purifies exhaust gas from the engine, and a purification device supplied to the purification device. a first air-fuel ratio sensor that detects a first air-fuel ratio that is the air-fuel ratio of the exhaust gas discharged from the engine; a second air-fuel ratio sensor that detects the second air-fuel ratio that is the air-fuel ratio of the exhaust gas discharged from the purification device; A particulate matter removal filter removes particulate matter contained in the exhaust gas, and a first air-fuel ratio is determined based on the first air-fuel ratio using a lean judgment value and a rich judgment value to determine the rich/lean balance of the catalyst atmosphere in the engine exhaust gas. and a control device that performs feedforward control to set the target air-fuel ratio to the target air-fuel ratio. The control device switches the rich-lean balance to feedback control in which the first air-fuel ratio is set as the target air-fuel ratio based on the second air-fuel ratio using the lean determination value and the rich determination value according to the scavenge rate. Scavenge is a phenomenon in which air flows from the intake pipe to the exhaust pipe when both the intake and exhaust valves are regenerated.Scavenge rate is calculated as the amount of air flowing from the intake pipe to the exhaust pipe relative to the amount of intake air. be done. When the scavenge rate is large and the amount of particulate matter deposited on the particulate matter removal filter increases, the estimated scavenge rate (estimated scavenge rate) becomes larger than the actual scavenge rate (actual scavenge rate). Since the correction amount of the feedforward control is increased as the scavenge rate increases, when the estimated scavenge rate becomes larger than the actual scavenge rate, the correction for making the air-fuel ratio stoichiometric becomes excessive. At this time, the air-fuel ratio becomes excessively rich, and the amount of unburned gas (HC) and incompletely combusted gas (CO) in the exhaust gas increases, resulting in poor emissions. In such a case, by switching to feedback control in which the first air-fuel ratio is set as the target air-fuel ratio based on the second air-fuel ratio, it is possible to suppress excessive richness of the air-fuel ratio and suppress deterioration of emissions. .

In the engine device of the present invention, the control device may change the lean determination value to a stoichiometric side when switching to feedback control based on the second air-fuel ratio. In this way, it is possible to prevent the catalyst atmosphere from becoming excessively lean.

In the engine device of the present invention, the control device may expand a rich-side value of the target air-fuel ratio to a rich side when switching to feedback control based on the second air-fuel ratio. In this way, when the catalyst atmosphere becomes lean, it can be quickly changed to the rich side. As a result, it is possible to prevent the catalyst atmosphere from becoming excessively lean.

In the engine device of the present invention, the control device may permit learning of a correction value for feedback control based on the second air-fuel ratio while executing feedforward control based on the first air-fuel ratio; Learning of the correction value for the feedback control based on the second air-fuel ratio may be prohibited while the feedback control based on the second air-fuel ratio is being executed. In this way, it is possible to prevent learning of the correction value for the feedback control based on the second air-fuel ratio in a state where the learning conditions are not appropriate due to a discrepancy between the estimated scavenge rate and the actual scavenge rate.

1 is a configuration diagram schematically showing the configuration of an engine device 10 according to an embodiment of the present invention. 7 is an explanatory diagram showing an example of input/output signals of the electronic control unit 70. FIG. 7 is a flowchart illustrating an example of a rich/lean balance control switching process of the catalyst atmosphere executed by the electronic control unit 70. FIG. FIG. 6 is an explanatory diagram showing an example of time changes in stoichiometric correction, target front air-fuel ratio, actual front air-fuel ratio, and actual rear air-fuel ratio in a comparative example and an example in a scavenge region.

Next, a mode for carrying out the present invention will be described using examples.

FIG. 1 is a configuration diagram showing an outline of the configuration of an engine device 10 as an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an example of input/output signals of an electronic control unit 70 included in the engine device 10. be. The engine device 10 of the embodiment is installed in a general vehicle that runs using power from an engine 12 and various hybrid vehicles that include a motor in addition to the engine 12, and as shown in FIGS. 1 and 2, It includes an engine 12, a variable valve timing mechanism 15, a supercharger 40, a purification device 37, a PM filter 38, a fuel supply device 16, and an electronic control unit 70.

The engine 12 is configured as an internal combustion engine that outputs power using fuel such as gasoline or diesel oil supplied from the fuel tank 11. This engine 12 includes a port injection valve 28 that injects fuel into an intake port, an in-cylinder injection valve 29 that injects fuel into a combustion chamber 31, and a spark plug 32. The in-cylinder injection valve 29 is arranged approximately at the center of the top of the combustion chamber 31, and injects fuel in a spray form. The spark plug 32 is arranged near the in-cylinder injection valve 29 so as to ignite the fuel sprayed from the in-cylinder injection valve 29.

The engine 12 has a port injection valve 28 and an in-cylinder injection valve 29, so that it can be operated in any one of a port injection mode, an in-cylinder injection mode, and a shared injection mode. In the embodiment, the ratio of the fuel injection amount by the port injection valve 28 to the total fuel injection amount is set as the port injection ratio Rp (0≦Rp≦1), and the port injection mode is a case where the port injection ratio Rp is the value 1, The in-cylinder injection mode is when the port injection ratio Rp is 0, and the shared injection mode is when the port injection ratio Rp is greater than 0 and smaller than 1 (0<Rp<1).

In the port injection mode, air purified by the air cleaner 22 is sucked into the intake pipe 23, passes through the intercooler 25, throttle valve 26, and surge tank 27 in this order, and performs port injection on the downstream side of the surge tank 27 in the intake pipe 23. Fuel is injected from the valve 28 to mix air and fuel. This air-fuel mixture is sucked into the combustion chamber 31 through the intake valve 30, and exploded and combusted by electric sparks from the ignition plug 32. Then, the reciprocating motion of the piston 33, which is pushed down by the energy generated by the explosive combustion, is converted into the rotational motion of the crankshaft 14. In the direct injection mode, air is sucked into the combustion chamber 31 in the same way as in the port injection mode, and fuel is injected from the direct injection valve 29 once or multiple times during the intake stroke, compression stroke, or expansion stroke, and ignition is performed. The electrical spark generated by the plug 32 causes explosive combustion and rotational movement of the crankshaft 14 is obtained. In particular, when injecting fuel during the expansion stroke, the fuel injection from the in-cylinder injection valve 29 and the ignition from the spark plug 32 during the expansion stroke are synchronized so that the sprayed fuel injected from the in-cylinder injection valve 29 can be ignited. It is done. In the shared injection mode, fuel is injected from the port injection valve 28 when air is taken into the combustion chamber 31, and fuel is injected from the in-cylinder injection valve 29 once or multiple times during the intake stroke, compression stroke, or expansion stroke. The fuel is injected and exploded and combusted by the electric spark from the spark plug 32 to obtain rotational motion of the crankshaft 14.

Exhaust gas discharged from the combustion chamber 31 to the exhaust pipe 35 via the exhaust valve 34 is processed by a catalyst (three-way catalyst) that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). ) and a PM filter 38 that removes particulate matter (such as soot) in the exhaust gas, and is discharged to the outside air. Incidentally, a starter (not shown) that cranks the engine 12 and an alternator 48 that generates electricity using the power of the engine 12 are attached to the crankshaft 14 . The alternator 48 supplies generated power from a battery (not shown) to a power line that supplies power to the fan motor 38d, water pump 38e, etc. of the engine cooling system 38.

The variable valve timing mechanism 15 changes the opening and closing timing of the intake valve 30 by advancing or retarding the rotational position of the intake camshaft that opens and closes the intake valve 30 that performs intake and exhaust into the combustion chamber. The exhaust valve 34 is configured as a well-known mechanism that advances or retards the rotational position of the exhaust camshaft that opens and closes the exhaust valve 34 to change the opening and closing timing of the exhaust valve 34.

The fuel supply device 16 includes a fuel tank 11, a feed pump 11p, a low pressure supply pipe 17, a high pressure pump 18, and a high pressure supply pipe 19. Fuel from the fuel tank 11 is fed under pressure by a feed pump 11p and is supplied to a port injection valve 28 via a low pressure supply pipe 17. The feed pump 11p is configured as an electric pump that operates by receiving power from a battery (not shown), and is arranged in the fuel tank 11. Although not shown, a check valve is also attached to the low-pressure supply pipe 17 to allow fuel to flow from the feed pump 11p side to the port injection valve 28 side and to restrict the flow of fuel in the opposite direction. Further, fuel from the low-pressure supply pipe 17 is pumped by a high-pressure pump 18 and is supplied to an in-cylinder injection valve 29 via a high-pressure supply pipe 19. The high-pressure pump 18 is configured as a pump driven by power from the engine 12 (in the embodiment, rotation of an intake camshaft that opens and closes the intake valve 30). The high-pressure pump 18 has an electromagnetic valve 18a connected to its suction port that opens and closes when pressurizing fuel, and a check valve connected to its discharge port that regulates backflow of fuel and maintains the fuel pressure in the high-pressure supply pipe 19. It has a valve 18b and a plunger 18c that is actuated by the rotation of the engine 12 (rotation of the intake camshaft), and when the electromagnetic valve 18a is opened while the engine 12 is operating, it sucks fuel from the low pressure supply pipe 17. When the electromagnetic valve 18a is closed, the fuel compressed by the plunger 18c is intermittently fed into the high-pressure supply pipe 19 via the check valve 18b, thereby pressurizing the fuel supplied to the high-pressure supply pipe 19. Note that when the high-pressure pump 18 is driven, the fuel pressure in the low-pressure supply pipe 17 and the fuel pressure (fuel pressure) in the high-pressure supply pipe 19 pulsate in accordance with the rotation of the engine 12 (rotation of the intake camshaft).

The supercharger 40 is configured as a turbocharger and includes a compressor 41, a turbine 42, a rotating shaft 43, a wastegate valve 44, and a blow-off valve 45. Compressor 41 is arranged upstream of intercooler 25 in intake pipe 23 . The turbine 42 is disposed upstream of the purifying device 37 of the exhaust pipe 35. The rotating shaft 43 connects the compressor 41 and the turbine 42. The wastegate valve 44 is provided in a bypass pipe 36 that communicates between the upstream side and the downstream side of the turbine 42 in the exhaust pipe 35, and is controlled by the electronic control unit 70. The blow-off valve 45 is provided in the bypass pipe 24 that communicates between the upstream side and the downstream side of the compressor 41 in the intake pipe 23, and is controlled by the electronic control unit 70.

In this supercharger 40, by adjusting the opening degree of the waste gate valve 44, the distribution ratio between the amount of exhaust gas flowing through the bypass pipe 36 and the amount of exhaust gas flowing through the turbine 42 is adjusted, and the rotational driving force of the turbine 42 is adjusted. The amount of compressed air by the compressor 41 is adjusted, and the supercharging pressure (intake pressure) of the engine 12 is adjusted. Here, the distribution ratio is adjusted so that, in detail, the smaller the opening degree of the wastegate valve 44, the smaller the amount of exhaust gas flowing through the bypass pipe 36 and the larger the amount of exhaust gas flowing through the turbine 42. Note that when the wastegate valve 44 is fully open, the engine 12 can operate in the same manner as a naturally aspirated engine that does not include the supercharger 40.

In addition, in the supercharger 40, when the pressure on the downstream side of the compressor 41 in the intake pipe 23 is higher than the pressure on the upstream side to some extent, by opening the blow-off valve 45, the surplus on the downstream side of the compressor 41 is Pressure can be released. Note that the blow-off valve 45 is configured as a check valve that opens when the pressure downstream of the compressor 41 in the intake pipe 23 becomes higher than the pressure upstream to some extent, instead of a valve controlled by the electronic control unit 70. It is also possible to do so.

The electronic control unit 70 is configured as a microprocessor centered on a CPU, and in addition to the CPU, includes a ROM that stores processing programs, a RAM that temporarily stores data, and a nonvolatile flash that stores and retains data. Equipped with memory, input/output ports, and communication ports. Signals from various sensors are input to the electronic control unit 70 via input ports.

Examples of signals input to the electronic control unit 70 include the tank internal pressure Ptnk from the internal pressure sensor 11a that detects the pressure inside the fuel tank 11, and the crank position sensor 14a that detects the rotational position of the crankshaft 14 of the engine 12. Examples include the crank angle θcr, the cooling water temperature Tw from a water temperature sensor (not shown) that detects the temperature of the cooling water of the engine 12, and the throttle opening TH from the throttle position sensor 26a that detects the opening of the throttle valve 26. The cam position θca from a cam position sensor (not shown) that detects the rotational position of an intake camshaft that opens and closes the intake valve 30 and an exhaust camshaft that opens and closes the exhaust valve 34 can also be cited. The intake air amount Qa from the air flow meter 23a installed upstream of the compressor 41 in the intake pipe 23, the intake temperature Tin from the intake air temperature sensor 23t installed upstream of the compressor 41 in the intake pipe 23, and the intake air Intake pressure (compressor prepressure) Pin from the intake pressure sensor 23b installed upstream of the compressor 41 in the intake pipe 23, supercharging pressure sensor 23c installed between the compressor 41 in the intake pipe 23 and the intercooler 25 The supercharging pressure Pc from . The surge pressure (throttle after pressure) Ps from the surge pressure sensor 27a attached to the surge tank 27 and the surge temperature Ts from the temperature sensor 27b attached to the surge tank 27 can also be mentioned. Examples include the low fuel pressure Pfp from the fuel pressure sensor 28a that detects the fuel pressure of fuel supplied to the port injection valve 28 and the high fuel pressure Pfd from the fuel pressure sensor 29a that detects the fuel pressure of fuel supplied to the in-cylinder injection valve 29. The front air-fuel ratio AF1 from the front air-fuel ratio sensor 35a installed on the upstream side of the purification device 37 in the exhaust pipe 35, and the rear air-fuel ratio AF1 from the rear air-fuel ratio sensor 35b installed on the downstream side of the purification device 37 in the exhaust pipe 35. The air-fuel ratio AF2, the exhaust pressure Pex from the exhaust pressure sensor 35c attached to the exhaust pipe 35, and the filter differential pressure Ppm from the differential pressure sensors 39 attached to the upstream and downstream sides of the PM filter 38 can also be mentioned.

Various control signals are output from the electronic control unit 70 via an output port. The signals output from the electronic control unit 70 include, for example, a control signal to the variable valve timing mechanism 15, a control signal to the throttle valve 26, a control signal to the port injection valve 28, and a control signal to the in-cylinder injection valve 29. A control signal to the spark plug 32 can be mentioned. Examples include a control signal to the waste gate valve 44, a control signal to the blow-off valve 45, and a control signal to the electromagnetic valve 18a.

The electronic control unit 70 calculates the rotational speed Ne of the engine 12 and the load factor (ratio of the volume of air actually taken in in one cycle to the stroke volume per cycle of the engine 12) KL. The rotation speed Ne is calculated based on the crank angle θcr from the crank position sensor 14a. The load factor KL is calculated based on the intake air amount Qa from the air flow meter 23a and the rotational speed Ne. The electronic control unit 70 calculates a scavenge rate Sc, which is the ratio of the amount of air flowing from the intake pipe to the exhaust pipe to the amount of intake air. In the embodiment, the scavenging rate Sc is determined by the difference between the pressure in the intake pipe 23 (surge pressure Ps from the surge pressure sensor 27a) and the pressure in the exhaust pipe 35 (exhaust pressure Pex from the exhaust pressure sensor 35c) and the scavenging rate Sc. The relationship between the two is determined in advance through experiments or machine learning, and stored as a scavenge rate setting map, and when the differential pressure between the pressure in the intake pipe 23 and the pressure in the exhaust pipe 35 is given, the corresponding scavenge rate is derived from the map. It is assumed that the calculation is performed by

In the engine device 10 of the embodiment configured in this manner, the electronic control unit 70 controls the amount of intake air that controls the opening degree of the throttle valve 26 based on the required load factor KL* of the engine 12, and controls the intake air amount from the port injection valve 28. fuel injection control that controls fuel injection from the in-cylinder injection valve 29, ignition control that controls the ignition timing of the spark plug 32, supercharging control that controls the opening degree of the waste gate valve 44, and control of the solenoid valve 18a. The fuel pressure of the high pressure supply pipe 19 is controlled by opening and closing. The fuel injection control includes setting of the fuel injection amount to set the fuel injection amount from the port injection valve 28 and the fuel injection amount from the in-cylinder injection valve 29, injection timing of the port injection valve 28, and injection of the in-cylinder injection valve 29. This includes setting the fuel injection timing.

Next, the operation of the engine device 10 of the embodiment, particularly the operation when controlling the rich/lean balance of the catalyst atmosphere in the purification device 37, will be described. FIG. 3 is a flowchart illustrating an example of a rich/lean balance control switching process of the catalyst atmosphere executed by the electronic control unit 70.

When the control switching process is executed, the electronic control unit 70 first determines whether or not the area is a scavenge area (step S100). It can be determined whether the area is a scavenge area or not by determining whether the scavenge rate is equal to or higher than a threshold value (for example, 2% or 5%).

When it is determined in step S100 that the scavenge region is not present, feedforward control is performed based on the front air-fuel ratio AF1 in the rich-lean balance of the catalyst atmosphere (step S110), and the rear air-fuel ratio AF2 is adjusted to the rear air-fuel ratio AF2 in the rich-lean balance of the catalyst atmosphere. The learning of the correction value for the feedforward control based on the feedforward control is permitted (step S120), and the present process ends. Feedforward control based on the front air-fuel ratio AF1 in the rich-lean balance of the catalyst atmosphere sets a rich target value to the target front air-fuel ratio AF1* when the front air-fuel ratio AF1 exceeds a predetermined lean judgment value, and When the air-fuel ratio AF1 falls below a predetermined rich judgment value, a lean target value is set for the target front air-fuel ratio AF1*, and the fuel injection amount is controlled so that the front air-fuel ratio AF1 becomes the target front air-fuel ratio AF1*. Do it by doing this.

When it is determined in step S100 that the vehicle is in the scavenge region, feedback control is performed based on the rear air-fuel ratio AF2 of the rich-lean balance of the catalyst atmosphere (step S130). This feedback control sets a rich target value to the target front air-fuel ratio AF1* when the rear air-fuel ratio AF2 exceeds a predetermined lean judgment value, and when the rear air-fuel ratio AF2 falls below a predetermined rich judgment value. This is done by setting the target front air-fuel ratio AF1* to a lean target value and controlling the fuel injection amount so that the front air-fuel ratio AF1 becomes the target front air-fuel ratio AF1*. In the scavenging region, when the amount of particulate matter deposited on the PM filter 38 increases, the back pressure in scavenging (pressure in the exhaust pipe 35) increases, and the calculated scavenging rate Sc becomes larger than the actual scavenging rate. Therefore, when feedforward control is executed based on the front air-fuel ratio AF1 of the rich-lean balance of the catalyst atmosphere, the stoichiometric correction for making the air-fuel ratio AF stoichiometric becomes excessive, and the catalyst atmosphere becomes rich. In order to avoid this, feedback control is performed based on the rear air-fuel ratio AF2.

At this time, the lean determination value is changed to the stoichiometric side (step S140), and the rich target value of the target front air-fuel ratio AF1* is expanded to the rich side (step S150). The amount of change in the lean determination value toward the stoichiometric side may be, for example, 0.2, 0.3, or 0.4 as the air-fuel ratio. By changing the lean determination value to the stoichiometric side in this manner, it is possible to shorten the time that the catalyst atmosphere is in a lean state and suppress an increase in nitrogen oxide NOx in the exhaust gas. The amount of expansion of the rich target value of the target front air-fuel ratio AF1* to the rich side can be, for example, 0.2, 0.3, 0.4, etc. as the air-fuel ratio. By expanding the rich target value of the target front air-fuel ratio AF1* to the rich side in this way, it is possible to quickly change the catalyst atmosphere to the rich side when it becomes lean, thereby reducing the increase in nitrogen oxides (NOx) in the exhaust gas. Can be suppressed.

Then, learning of the correction value for the feedforward control based on the rear air-fuel ratio AF2 of the rich/lean balance of the catalyst atmosphere is prohibited (step S150), and the present process ends. It is inappropriate to prohibit learning of the feedforward control correction value based on the rear air-fuel ratio AF2 by changing the lean judgment value to the stoichiometric side or expanding the rich target value of the standard front air-fuel ratio AF1* to the rich side. This is to prevent the correction value from being learned.

FIG. 4 shows an example of temporal changes in the scavenging rate Sc, the output of the front air-fuel ratio sensor 35a, the stoichiometric correction in the comparative example and the example, the target front air-fuel ratio AF1*, the actual front air-fuel ratio AF1, and the actual rear air-fuel ratio AF2. It is an explanatory diagram. As a comparative example, one was used in which the rich/lean balance of the catalyst atmosphere was performed by feedforward control based on the front air-fuel ratio AF1 even in the scavenge region. In the comparative example, since feedforward control is performed based on the front air-fuel ratio AF1 even in the scavenge region, the stoichiometric correction for making the air-fuel ratio AF stoichiometric becomes excessive, resulting in a rich catalyst atmosphere. On the other hand, in the embodiment, the rich/lean balance of the catalyst atmosphere is performed by feedback control based on the rear air-fuel ratio AF2 in the scavenge region, so that the stoichiometric correction is stable.

In the engine device 10 of the embodiment described above, when it is determined that the scavenge region is present, feedback control is performed based on the rear air-fuel ratio AF2 of the rich-lean balance of the catalyst atmosphere. Thereby, even in the scavenge region, it is possible to suppress excessive stoichiometric correction compared to the case where feedforward control is performed based on the front air-fuel ratio AF1 of the rich-lean balance of the catalyst atmosphere.

In the engine device 10 of the embodiment, when performing feedback control based on the rear air-fuel ratio AF2 of the rich-lean balance of the catalyst atmosphere in the scavenging region, the lean determination value is changed to the stoichiometric side. This makes it possible to shorten the time during which the catalyst atmosphere is in a lean state and suppress an increase in nitrogen oxide NOx in the exhaust gas.

In the engine device 10 of the embodiment, when performing feedback control based on the rear air-fuel ratio AF2 of the rich-lean balance of the catalyst atmosphere in the scavenge region, the rich target value of the target front air-fuel ratio AF1* is expanded to the rich side. Thereby, when the catalyst atmosphere becomes lean, it can be quickly changed to the rich side, and an increase in nitrogen oxide NOx in the exhaust gas can be suppressed.

In the engine device 10 of the embodiment, an engine 12 in which the in-cylinder injection valve 29 is disposed approximately at the center of the top of the combustion chamber 31 is used. ) may be used.

In the engine device 10 of the embodiment, the supercharger 40 is configured as a turbocharger in which a compressor 41 disposed in the intake pipe 23 and a turbine 42 disposed in the exhaust pipe 35 are connected via a rotating shaft 43. I took it as a thing. However, instead of this, a compressor driven by the engine 12 or a motor may be configured as a supercharger disposed in the intake pipe 23.

The correspondence between the main elements of the embodiments and the main elements of the invention described in the column of means for solving the problems will be explained. In the embodiment, the supercharger 40 corresponds to a "supercharger", the port injection valve 28 corresponds to a "port injection valve", the in-cylinder injection valve 29 corresponds to a "in-cylinder injection valve", and the engine 12 corresponds to the "engine", the purification device 37 corresponds to the "purification device", and the electronic control unit 70 corresponds to the "control device".

The correspondence relationship between the main elements of the examples and the main elements of the invention described in the column of means for solving the problem is that the example implements the invention described in the column of means for solving the problem. Since this is an example for specifically explaining a form for solving the problem, it is not intended to limit the elements of the invention described in the column of means for solving the problems. In other words, the interpretation of the invention described in the column of means for solving the problem should be based on the description in that column, and the examples are based on the description of the invention described in the column of means for solving the problem. This is just one specific example.

Although the embodiments of the present invention have been described above using examples, the present invention is not limited to these examples in any way, and may be modified in various forms without departing from the gist of the present invention. Of course, it can be implemented.

INDUSTRIAL APPLICATION This invention can be utilized for the manufacturing industry of an engine device, etc.

10 engine device, 11 fuel tank, 11a internal pressure sensor, 11p feed pump, 12 engine, 14 crankshaft, 14a crank position sensor, 15 variable valve timing mechanism, 16 fuel supply device, 17 low pressure supply pipe, 18 high pressure pump, 18a electromagnetic Valve, 18b Check valve, 18c Plunger, 19 High pressure supply pipe, 22 Air cleaner, 23 Intake pipe, 23a Air flow meter, 23b Intake pressure sensor, 23c Supercharging pressure sensor, 24 Bypass pipe, 25 Intercooler, 26 Throttle valve, 26a Throttle Position sensor, 27 Surge tank, 27a Surge pressure sensor, 27b Temperature sensor, 28 In-cylinder injection valve, 28a Fuel pressure sensor, 29 Intake valve, 30 Combustion chamber, 31 Spark plug, 32 Piston, 34 Exhaust valve, 35 Exhaust pipe, 35a Front air-fuel ratio sensor, 35b Rear air-fuel ratio sensor, 35c Exhaust pressure sensor, 36 Bypass pipe, 37 Purifier, 38 PM filter, 39 Differential pressure sensor, 40 Supercharger, 41 Compressor, 42 Turbine, 43 Rotating shaft, 44 Waste Gate valve, 45 blow-off valve, 70 electronic control unit.

Claims (4)

An engine having a supercharger, a variable valve timing mechanism, a port injection valve, and an in-cylinder injection valve;
a purification device having a purification catalyst that purifies exhaust gas from the engine;
a first air-fuel ratio sensor that detects a first air-fuel ratio that is an air-fuel ratio of exhaust gas supplied to the purification device;
a second air-fuel ratio sensor that detects a second air-fuel ratio that is an air-fuel ratio of exhaust gas discharged from the purification device;
a particulate matter removal filter that removes particulate matter contained in exhaust from the engine;
control for performing feedforward control to set the first air-fuel ratio detected by the first air-fuel ratio sensor as a target air-fuel ratio using a lean judgment value and a rich judgment value to determine the rich-lean balance of a catalyst atmosphere in the exhaust gas of the engine; a device;
An engine device comprising:
The control device adjusts the rich/lean balance according to a scavenge rate to a first air-fuel ratio based on the second air-fuel ratio detected by the second air-fuel ratio sensor using the lean determination value and the rich determination value. Switch to feedback control with the target air-fuel ratio,
An engine device characterized by: The engine device according to claim 1,
The control device changes the lean determination value to a stoichiometric side when switching to feedback control based on the second air-fuel ratio.
engine equipment. The engine device according to claim 1,
The control device expands a rich side value of the target air fuel ratio to a rich side when switching to feedback control based on the second air fuel ratio.
engine equipment. An engine device according to any one of claims 1 to 3, comprising:
The control device allows learning of a correction value for feedback control based on the second air-fuel ratio while performing feedforward control based on the first air-fuel ratio, and performs feedback control based on the second air-fuel ratio. Prohibits learning of a correction value for feedback control based on the second air-fuel ratio while executing the second air-fuel ratio;
engine equipment.

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