Engine equipment

Abstract

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

Description

[Technical Field]

[0001] The present invention relates to an engine device. [Background technology]

[0002] Conventionally, as an engine device of this type, one has been proposed in which the target air-fuel ratio is alternately set to a rich air-fuel ratio and a lean air-fuel ratio, and the air-fuel ratio of the exhaust gas is controlled so that the output air-fuel ratio of an air-fuel ratio sensor becomes the target air-fuel ratio (see, for example, 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, thereby purifying unburned gas in the exhaust gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-057760 Summary of the Invention [Problem to be solved by the invention]

[0004] In an engine equipped with a particulate matter removal filter, if the amount of particulate matter accumulated on the particulate matter removal filter increases, the back pressure of the engine's exhaust increases, the estimated scavenging rate becomes higher than the actual scavenging rate, and the correction amount for making the air-fuel ratio stoichiometric becomes excessive. This results in an increase in unburned gas (HC) and incompletely burned gas (CO) in the exhaust, which can worsen emissions.

[0005] The main object of the engine device of the present invention is to suppress the deterioration of emissions when the scavenging rate is high. [Means for solving the problem]

[0006] The engine device of the present invention employs the following means to achieve the above-mentioned main object.

[0007] The engine device of the present invention comprises: an engine having a turbocharger, 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, which is the air-fuel ratio of the exhaust gas supplied to the purification device; a second air-fuel ratio sensor that detects a second air-fuel ratio, which is the air-fuel ratio of the 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 a rich-lean balance of a catalyst atmosphere in the exhaust gas of the engine based on the first air-fuel ratio using a lean determination value and a rich determination value so that the first air-fuel ratio becomes a target air-fuel ratio; An engine device comprising: the control device switches the rich-lean balance to feedback control in which the first air-fuel ratio is set to a target 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 according to a scavenging rate. It is characterized by:

[0008] The engine system of the present invention includes an engine having a turbocharger, a variable valve timing mechanism, port injection valves, and in-cylinder injection valves, a purification device having a purification catalyst for purifying exhaust gas from the engine, a first air-fuel ratio sensor for detecting a first air-fuel ratio which is the air-fuel ratio of exhaust gas supplied to the purification device, a second air-fuel ratio sensor for detecting a second air-fuel ratio which is the air-fuel ratio of exhaust gas discharged from the purification device, a particulate matter removal filter for removing particulate matter contained in the exhaust gas from the engine, and a control device that performs feedforward control of the rich-lean balance of the catalyst atmosphere in the exhaust gas from the engine using a lean determination value and a rich determination value, with the first air-fuel ratio set to a target air-fuel ratio based on the first air-fuel ratio. The control device switches to feedback control of the rich-lean balance based on the second air-fuel ratio using the lean determination value and the rich determination value in accordance with the scavenging rate, with the first air-fuel ratio set to the target air-fuel ratio. Scavenging is a phenomenon in which air flows from the intake pipe to the exhaust pipe when both the intake valve and the exhaust valve are in regenerative regeneration mode. The scavenging rate is calculated, for example, as the amount of air flowing from the intake pipe to the exhaust pipe relative to the intake air volume. When the scavenging rate is high, the amount of particulate matter deposited on the particulate matter removal filter increases, resulting in an estimated scavenging rate (estimated scavenging rate) greater than the actual scavenging rate (actual scavenging rate). Because the feedforward control correction amount increases with increasing scavenging rate, when the estimated scavenging rate exceeds the actual scavenging rate, excessive correction is required to make the air-fuel ratio stoichiometric. In this case, the air-fuel ratio becomes excessively rich, resulting in increased amounts of unburned gas (HC) and incompletely burned gas (CO) in the exhaust, resulting in worsening emissions. In such cases, switching to feedback control in which the first air-fuel ratio is set to the target air-fuel ratio based on the second air-fuel ratio can prevent the air-fuel ratio from becoming excessively rich, thereby suppressing worsening emissions.

[0009] In the engine system of the present invention, the control device may change the lean determination value to the stoichiometric side when switching to feedback control based on the second air-fuel ratio, thereby preventing the catalyst atmosphere from becoming excessively lean.

[0010] In the engine system of the present invention, the control device may increase the rich side value of the target air-fuel ratio when switching to feedback control based on the second air-fuel ratio. This allows the catalyst atmosphere to be quickly shifted to the rich side when it becomes lean. As a result, the catalyst atmosphere can be prevented from becoming excessively lean.

[0011] In the engine apparatus 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, and prohibit learning of the correction value for feedback control based on the second air-fuel ratio while executing feedback control based on the second air-fuel ratio. This makes it possible to prevent learning of the correction value for feedback control based on the second air-fuel ratio when learning conditions are not appropriate due to a deviation between the estimated scavenging rate and the actual scavenging rate. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing an outline of the configuration of an engine device 10 according to an embodiment of the present invention. [Figure 2] 3 is an explanatory diagram showing an example of input / output signals of an electronic control unit 70. FIG. [Figure 3] 10 is a flowchart showing an example of a rich / lean balance control switching process for the catalyst atmosphere executed by the electronic control unit 70. [Figure 4] 10A and 10B are explanatory diagrams showing an example of time-dependent 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 embodiment in the scavenge region. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, a mode for carrying out the present invention will be described using examples. [Example]

[0014] 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. The engine device 10 of the embodiment is mounted on a general vehicle that travels using power from the engine 12 or various hybrid vehicles that include a motor in addition to the engine 12. As shown in FIGS. 1 and 2, the engine device 10 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.

[0015] The engine 12 is configured as an internal combustion engine that outputs power using fuel such as gasoline or light oil supplied from a fuel tank 11. The engine 12 has 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 disposed substantially at the center of the top of the combustion chamber 31 and injects fuel in a spray form. The spark plug 32 is disposed in the vicinity of the in-cylinder injection valve 29 so as to be able to ignite the fuel sprayed in a spray form from the in-cylinder injection valve 29.

[0016] By having the port injection valve 28 and the in-cylinder injection valve 29, the engine 12 can be operated in any one of a port injection mode, an in-cylinder injection mode, and a common 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 defined as a port injection ratio Rp (0 ≦ Rp ≦ 1). The port injection mode is the case where the port injection ratio Rp has a value of 1, the in-cylinder injection mode is the case where the port injection ratio Rp has a value of 0, and in the common injection mode, the port injection ratio Rp is greater than 0 and less than 1 (0 < Rp < 1).

[0017] In the port injection mode, air purified by the air cleaner 22 is drawn into the intake pipe 23 and passes through the intercooler 25, throttle valve 26, and surge tank 27 in that order. Fuel is injected from a port injection valve 28 downstream of the surge tank 27 in the intake pipe 23, mixing the air and fuel. This mixture is drawn into a combustion chamber 31 via an intake valve 30 and is explosively combusted by an electric spark from an ignition plug 32. The reciprocating motion of a piston 33, which is pushed down by the energy of the explosive combustion, is converted into rotational motion of the crankshaft 14. In the direct injection mode, as in the port injection mode, air is drawn into the combustion chamber 31, and fuel is injected from the direct injection valve 29 once or multiple times during the intake stroke, compression stroke, or expansion stroke. The fuel is explosively combusted by an electric spark from the ignition plug 32, generating rotational motion of the crankshaft 14. In particular, when fuel is injected during the expansion stroke, fuel injection from the in-cylinder injection valve 29 during the expansion stroke is synchronized with ignition from the spark plug 32 so that the spray-like fuel injected from the in-cylinder injection valve 29 can be ignited. In the combined injection mode, fuel is injected from the port injection valve 28 when air is drawn 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, and the fuel is explosively burned by an electric spark from the spark plug 32, generating rotational motion of the crankshaft 14.

[0018] The exhaust gas discharged from the combustion chamber 31 into the exhaust pipe 35 via the exhaust valve 34 is discharged into the outside air via a purification device 37 having 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) from the exhaust gas.

[0019] The variable valve timing mechanism 15 is The intake valve 30 that intakes and exhausts air into the combustion chamber is opened and closed. The intake camshaft rotates in a direction that advances or retards the rotational position of the intake camshaft, which controls the intake valve 30, to change the opening and closing timing of the intake valve 30, and the exhaust camshaft rotates in a direction that advances or retards the rotational position of the exhaust camshaft, which controls the exhaust valve 34, to change the opening and closing timing of the exhaust valve 34.

[0020] The fuel supply system 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 pumped by the feed pump 11p and supplied to the port injection valve 28 via the 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 disposed in the fuel tank 11. Although not shown, the low-pressure supply pipe 17 is also equipped with a check valve that allows fuel to flow from the feed pump 11p side toward the port injection valve 28 side and restricts fuel flow in the opposite direction. Furthermore, fuel from the low-pressure supply pipe 17 is pumped by the high-pressure pump 18 and supplied to the in-cylinder injection valve 29 via the high-pressure supply pipe 19. The high-pressure pump 18 is configured as a pump driven by power from the engine 12 (in this embodiment, rotation of the intake camshaft that opens and closes the intake valve 30). The high-pressure pump 18 has an electromagnetic valve 18a connected to its intake port that opens and closes when pressurizing fuel, a check valve 18b connected to its discharge port that restricts backflow of fuel and maintains the fuel pressure in the high-pressure supply pipe 19, and a plunger 18c that is actuated by the rotation of the engine 12 (rotation of the intake camshaft).When the electromagnetic valve 18a is open while the engine 12 is running, the high-pressure pump 18 draws in fuel from the low-pressure supply pipe 17, and when the electromagnetic valve 18a is closed, the fuel compressed by the plunger 18c is intermittently sent to the high-pressure supply pipe 19 via the check valve 18b, thereby pressurizing the fuel to be supplied to the high-pressure supply pipe 19. Note that when the high-pressure pump 18 is operating, the fuel pressure (fuel pressure) in the low-pressure supply pipe 17 and the high-pressure supply pipe 19 pulsates in accordance with the rotation of the engine 12 (rotation of the intake camshaft).

[0021] 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. The compressor 41 is disposed upstream of the intercooler 25 in the intake pipe 23. The turbine 42 is disposed upstream of the purification device 37 in 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 connects the upstream side and downstream side of the turbine 42 in the exhaust pipe 35, and is controlled by an electronic control unit 70. The blow-off valve 45 is provided in a bypass pipe 24 that connects the upstream side and downstream side of the compressor 41 in the intake pipe 23, and is controlled by the electronic control unit 70.

[0022] In this turbocharger 40, the opening degree of the wastegate valve 44 is adjusted to adjust 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, thereby adjusting the rotational driving force of the turbine 42, adjusting the amount of air compressed by the compressor 41, and adjusting the supercharging pressure (intake pressure) of the engine 12. More specifically, the distribution ratio is adjusted so that the smaller the opening degree of the wastegate valve 44, the less the amount of exhaust gas flowing through the bypass pipe 36 and the more the amount of exhaust gas flowing through the turbine 42. 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 have a turbocharger 40.

[0023] Furthermore, in the turbocharger 40, when the pressure downstream of the compressor 41 in the intake pipe 23 is somewhat higher than the pressure upstream thereof, the blow-off valve 45 is opened, thereby making it possible to release excess pressure downstream of the compressor 41. Note that, instead of being a valve controlled by the electronic control unit 70, the blow-off valve 45 may be configured as a check valve that opens when the pressure downstream of the compressor 41 in the intake pipe 23 becomes somewhat higher than the pressure upstream thereof.

[0024] The electronic control unit 70 is configured as a microprocessor centered on a CPU, and in addition to the CPU, is equipped with a ROM for storing processing programs, a RAM for temporarily storing data, a non-volatile flash memory for storing and retaining data, input / output ports, and communication ports.Signals from various sensors are input to the electronic control unit 70 via the input ports.

[0025] Examples of signals input to the electronic control unit 70 include a tank internal pressure Ptnk from an internal pressure sensor 11a that detects the pressure inside the fuel tank 11, a crank angle θcr from a crank position sensor 14a that detects the rotational position of the crankshaft 14 of the engine 12, a coolant temperature Tw from a water temperature sensor (not shown) that detects the temperature of the coolant for the engine 12, and a throttle opening TH from a throttle position sensor 26a that detects the opening of the throttle valve 26. Other examples of signals input to the electronic control unit 70 include a cam position θca from a cam position sensor (not shown) that detects the rotational positions of an intake camshaft that opens and closes the intake valve 30 and an exhaust camshaft that opens and closes the exhaust valve 34. Other examples include the intake air amount Qa from an air flow meter 23a attached upstream of the compressor 41 in the intake pipe 23, the intake air temperature Tin from an intake air temperature sensor 23t attached upstream of the compressor 41 in the intake pipe 23, the intake pressure (pre-compressor pressure) Pin from an intake pressure sensor 23b attached upstream of the compressor 41 in the intake pipe 23, and the boost pressure Pc from a boost pressure sensor 23c attached between the compressor 41 in the intake pipe 23 and the intercooler 25. Other examples include the surge pressure (post-throttle pressure) Ps from a surge pressure sensor 27a attached to the surge tank 27 and the surge temperature Ts from a temperature sensor 27b attached to the surge tank 27. Other examples include the low-pressure fuel pressure Pfp from a fuel pressure sensor 28a that detects the pressure of fuel supplied to the port injection valve 28 and the high-pressure fuel pressure Pfd from a fuel pressure sensor 29a that detects the pressure of fuel supplied to the direct injection valve 29. Other examples include the front air-fuel ratio AF1 from the front air-fuel ratio sensor 35a attached upstream of the purification device 37 in the exhaust pipe 35, the rear air-fuel ratio AF2 from the rear air-fuel ratio sensor 35b attached downstream of the purification device 37 in the exhaust pipe 35, 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 upstream and downstream of the PM filter 38.

[0026] Various control signals are output from the electronic control unit 70 via output ports. Examples of signals output from the electronic control unit 70 include 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, a control signal to the in-cylinder injection valve 29, and a control signal to the spark plug 32. Other examples include a control signal to the wastegate valve 44, a control signal to the blow-off valve 45, and a control signal to the solenoid valve 18a.

[0027] The electronic control unit 70 calculates the rotation speed Ne and load factor KL (the ratio of the volume of air actually taken in per cycle to the stroke volume per cycle of the engine 12) of the engine 12. 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 rotation speed Ne and the intake air amount Qa from the air flow meter 23a. The electronic control unit 70 calculates a scavenging 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 calculated by determining in advance the relationship between the pressure 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 through experiments, machine learning, etc., and storing the relationship as a map for setting the scavenging rate.When the pressure difference between the pressure in the intake pipe 23 and the pressure in the exhaust pipe 35 is given, the corresponding scavenging rate is derived from the map.

[0028] In the engine system 10 of this embodiment configured as described above, the electronic control unit 70 performs intake air amount control that controls the opening of the throttle valve 26, fuel injection control that controls fuel injection from the port injection valves 28 and the in-cylinder injection valves 29, ignition control that controls the ignition timing of the spark plugs 32, supercharging control that controls the opening of the wastegate valve 44, and fuel pressure control in the high-pressure supply pipe 19 by opening and closing the electromagnetic valve 18a, based on the required load factor KL* of the engine 12. The fuel injection control includes fuel injection amount setting that sets the fuel injection amount from the port injection valves 28 and the in-cylinder injection valves 29, and fuel injection timing setting that sets the injection timing of the port injection valves 28 and the in-cylinder injection valves 29.

[0029] Next, a description will be given of the operation of the engine system 10 of the embodiment, in particular the operation when controlling the rich-lean balance of the catalyst atmosphere in the purification device 37. Fig. 3 is a flowchart showing an example of a control switching process for the rich-lean balance of the catalyst atmosphere executed by the electronic control unit 70.

[0030] When the control switching process is executed, the electronic control unit 70 first determines whether or not the region is in the scavenge region (step S100). The determination of whether or not the region is in the scavenge region can be made by determining whether or not the scavenge rate is equal to or greater than a threshold value (for example, 2% or 5%).

[0031] When it is determined in step S100 that the catalyst is not in the scavenge region, feedforward control is performed based on the front air-fuel ratio AF1 of the rich-lean balance of the catalyst atmosphere (step S110), and feedforward control is performed based on the rear air-fuel ratio AF2 of the rich-lean balance of the catalyst atmosphere (step S111). Feedback ControlThe learning of the correction value of (step S120) is permitted, and this process is terminated. The feedforward control of the rich-lean balance of the catalyst atmosphere based on the front air-fuel ratio AF1 is performed by setting the target front air-fuel ratio AF1* to a rich target value when the front air-fuel ratio AF1 exceeds a predetermined lean determination value, and by setting the target front air-fuel ratio AF1* to a lean target value when the front air-fuel ratio AF1 falls below the predetermined rich determination value, and by controlling the fuel injection amount so that the front air-fuel ratio AF1 becomes the target front air-fuel ratio AF1*.

[0032] If step S100 determines that the catalyst atmosphere 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 is performed by setting the target front air-fuel ratio AF1* to a rich target value when the rear air-fuel ratio AF2 exceeds a predetermined lean determination value, and by setting the target front air-fuel ratio AF1* to a lean target value when the rear air-fuel ratio AF2 falls below the predetermined rich determination value, and by controlling the fuel injection amount so that the front air-fuel ratio AF1 becomes the target front air-fuel ratio AF1*. In the scavenge region, as the amount of particulate matter deposited in the PM filter 38 increases, the back pressure (pressure in the exhaust pipe 35) during scavenging increases, and the calculated scavenge rate Sc becomes larger than the actual scavenge rate. Therefore, if feedforward control based on the front air-fuel ratio AF1 of the rich-lean balance of the catalyst atmosphere is performed, the stoichiometric correction to make the air-fuel ratio AF stoichiometric becomes excessive, causing the catalyst atmosphere to become rich. To avoid this, feedback control based on the rear air-fuel ratio AF2 is performed.

[0033] At this time, the lean determination value is changed toward the stoichiometric side (step S140), and the rich target value of the target front air-fuel ratio AF1* is increased toward the rich side (step S150). The amount by which the lean determination value is changed toward the stoichiometric side can be, for example, an air-fuel ratio of 0.2, 0.3, or 0.4. By changing the lean determination value toward the stoichiometric side in this way, the time during which the catalyst atmosphere is in a lean state can be shortened, thereby suppressing an increase in nitrogen oxides (NOx) in the exhaust gas. The amount by which the rich target value of the target front air-fuel ratio AF1* is increased toward the rich side can be, for example, an air-fuel ratio of 0.2, 0.3, or 0.4. By increasing the rich target value of the target front air-fuel ratio AF1* toward the rich side in this way, the catalyst atmosphere can be quickly changed toward the rich side when it becomes lean, thereby suppressing an increase in nitrogen oxides (NOx) in the exhaust gas.

[0034] And based on the rear air-fuel ratio AF2 of the rich-lean balance of the catalyst atmosphere Feedback Control The learning of the correction value based on the rear air-fuel ratio AF2 is prohibited (step S160), and the process ends. Feedback Control The reason for prohibiting learning of the correction value is that the lean judgment value is changed to the stoichiometric side. Target front air-fuel ratio AF1* This is to prevent an inappropriate correction value from being learned by expanding the rich target value to the rich side.

[0035] FIG. 4 is an explanatory diagram showing an example of time variations in the scavenge rate Sc, the output of the front air-fuel ratio sensor 35a, stoichiometry correction, target front air-fuel ratio AF1*, actual front air-fuel ratio AF1, and actual rear air-fuel ratio AF2 in the comparative example and the embodiment. The comparative example uses a system in which the rich-lean balance of the catalyst atmosphere is achieved by feedforward control based on the front air-fuel ratio AF1 even in the scavenge region. In the comparative example, because feedforward control based on the front air-fuel ratio AF1 is performed even in the scavenge region, the stoichiometry correction to make 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 achieved by feedback control based on the rear air-fuel ratio AF2 in the scavenge region, so the stoichiometry correction is stable.

[0036] In the engine system 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. This makes it possible to prevent excessive stoichiometric correction, even in the scavenge region, compared to when feedforward control is performed based on the front air-fuel ratio AF1 of the rich-lean balance of the catalyst atmosphere.

[0037] In the engine device 10 of the embodiment, when feedback control based on the rear air-fuel ratio AF2 of the rich-lean balance of the catalyst atmosphere is performed in the scavenge region, the lean determination value is changed to the stoichiometric side, thereby shortening the time that the catalyst atmosphere is in a lean state and suppressing an increase in nitrogen oxides (NOx) in the exhaust gas.

[0038] In the engine system 10 of the embodiment, when feedback control based on the rear air-fuel ratio AF2 of the rich-lean balance of the catalyst atmosphere in the scavenge region is performed, the rich target value of the target front air-fuel ratio AF1* is expanded to the rich side. This allows the catalyst atmosphere to be quickly shifted to the rich side when it becomes lean, thereby suppressing an increase in nitrogen oxides (NOx) in the exhaust.

[0039] In the engine device 10 of the embodiment, the engine 12 used is one in which the in-cylinder injection valve 29 is arranged approximately in the center of the top of the combustion chamber 31, but it is also possible to use an engine in which the in-cylinder injection valve 29 is arranged on the side wall (side) of the combustion chamber 31.

[0040] In the engine system 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 rotary shaft 43. However, instead of this, the supercharger may be configured as a supercharger in which a compressor driven by the engine 12 or a motor is disposed in the intake pipe 23.

[0041] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be explained below. In the embodiment, the turbocharger 40 corresponds to the "turbocharger," the port injection valve 28 corresponds to the "port injection valve," the in-cylinder injection valve 29 corresponds to the "in-cylinder injection valve," 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."

[0042] The correspondence between the main elements of the Examples and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the Examples are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the Examples are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0043] The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms within the scope that does not deviate from the gist of the present invention. [Industrial Applicability]

[0044] The present invention can be used in the engine device manufacturing industry and the like. [Explanation of symbols]

[0045] 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 solenoid 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 boost 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 port injection valve, 28a fuel pressure sensor, 29 in-cylinder injection valve, 29a fuel pressure sensor, 30 intake valve, 31 combustion chamber, 32 Spark plug, 33 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 Purification device, 38 PM filter, 39 Differential pressure sensor, 40 Turbocharger, 41 Compressor, 42 Turbine, 43 Rotating shaft, 44 Wastegate valve, 45 Blow-off valve, 70 Electronic control unit.

Claims

1. an engine having a turbocharger, 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, which is the air-fuel ratio of the exhaust gas supplied to the purification device; a second air-fuel ratio sensor that detects a second air-fuel ratio, which is the air-fuel ratio of the 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 a rich-lean balance of a catalyst atmosphere in exhaust gas from the engine, using a lean determination value and a rich determination value to set the first air-fuel ratio detected by the first air-fuel ratio sensor as a target air-fuel ratio, and feedback control of the rich-lean balance, using the lean determination value and the rich determination value to set the first air-fuel ratio as a target air-fuel ratio based on the second air-fuel ratio detected by the second air-fuel ratio sensor; An engine device comprising: The control device performs the feedforward control and permits learning of a correction value for the feedback control when the scavenge rate is not a scavenge region where the scavenge rate is equal to or greater than a threshold, and switches from the feedforward control to the feedback control and prohibits learning of the correction value for the feedback control when the scavenge rate is in the scavenge region. An engine device characterized by:

2. 2. The engine device according to claim 1, The control device changes the lean determination value to the stoichiometric side when switching to the feedback control. Engine equipment.

3. 2. The engine device according to claim 1, the control device increases the rich side value of the target air-fuel ratio to the rich side when switching to the feedback control. Engine equipment.

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