Engine system

Abstract

To suppress deterioration of ignitability.SOLUTION: In the engine system, the first threshold value determined by the intake pressure at the first timing is prepared in advance, the first timing is after an intake valve opening timing indicating a timing at which the intake valve changes from the closed state to the open state in one cycle of the engine, and is included in a period until the piston reaches the bottom dead center. The processor is configured to determine whether or not the intake pressure detected by the intake pressure sensor is smaller than a first threshold value, and execute an advancing process of relatively advancing an injection timing of fuel in the engine according to a pressure difference between the first threshold value and the intake pressure detected by the intake pressure sensor when it is determined that the intake pressure detected by the intake pressure sensor is smaller than the first threshold value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] For example, Patent Document 1 discloses a control device that controls the timing of fuel injection into an engine. In Patent Document 1, the tumble ratio is estimated based on changes in pressure inside a surge tank, and the greater the tumble ratio, the more delayed the fuel injection timing is. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-291876 Summary of the Invention [Problem to be solved by the invention]

[0004] During engine warm-up, fuel is difficult to vaporize, so it is desirable to improve ignition and burn the mixture by forming a rich mixture around the spark plug. However, when deposits accumulate on the engine's intake valves and intake ports, the deposits block some of the air being introduced into the cylinder, reducing the flow of gas within the cylinder. It is difficult to detect changes in the flow of gas within the cylinder due to deposit accumulation, and if the flow of gas within the cylinder reduces, for example, during engine warm-up, it becomes difficult to form a rich mixture around the spark plug, which can reduce ignition.

[0005] Therefore, an object of the present invention is to provide an engine system that can suppress a decrease in ignition performance. [Means for solving the problem]

[0006] In order to solve the above problem, an engine system according to one embodiment of the present invention comprises: an engine having a piston, a cylinder, an intake valve, and an exhaust valve; an intake manifold that introduces intake air into the engine; an intake pressure sensor that detects an intake pressure inside the intake manifold; a control device for controlling the engine; Equipped with The control device one or more processors; one or more memories coupled to said processor; and a first threshold value is prepared in advance, the first threshold value being determined by the intake pressure at a first timing during rapid warm-up of the engine in an initial state; the first timing is after an intake valve opening timing, which indicates a timing at which the intake valve changes from a closed state to an open state, during one cycle of the engine, and is included in a period before the piston reaches bottom dead center; The processor: In the engine in a current state, the engine is undergoing rapid warm-up and the intake pressure at the first timing is acquired by the intake pressure sensor; determining whether the intake pressure detected by the intake pressure sensor is smaller than the first threshold value; when it is determined that the intake pressure measured by the intake pressure sensor is smaller than the first threshold value, executing an advancement process to relatively advance a fuel injection timing in the engine in accordance with a pressure difference between the first threshold value and the intake pressure measured by the intake pressure sensor; Execute the process including. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress a decrease in ignition ability. [Brief explanation of the drawings]

[0008] [Figure 1]FIG. 1 is a schematic diagram showing an example of the configuration of an engine system according to this embodiment. [Figure 2] FIG. 2 is a partial cross-sectional view showing an example of the configuration of the engine according to this embodiment. [Figure 3] FIG. 3 is a partial cross-sectional view showing an example of the operation of an engine during warm-up when the gas flow in the cylinder according to this embodiment is reduced. [Figure 4] FIG. 4 is an explanatory diagram showing the first timing according to the present embodiment. [Figure 5] FIG. 5 is an explanatory diagram showing a modified example of the first timing according to the present embodiment. [Figure 6] FIG. 6 is a flowchart showing the flow of operations of the engine control unit according to this embodiment. [Figure 7] FIG. 7 is a flowchart showing the flow of operations of the engine control unit according to this embodiment. [Figure 8] FIG. 8 is a flowchart showing the flow of operations of the engine control unit according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0010] 1 is a schematic diagram showing an example of the configuration of an engine system 1 according to this embodiment. The engine system 1 is mounted on, for example, a vehicle 2. The engine system 1 includes an engine 10, an intake passage 12, an exhaust passage 14, an EGR passage 16, an intake pressure sensor (Manifold Absolute Pressure Sensor: MAPS) 18, a control device 20, and an alarm device 22.

[0011] The engine 10 is, for example, a reciprocating engine, and generates driving force by burning a mixture containing fuel and air. The generated driving force is transmitted to, for example, the wheels of the vehicle 2. The engine 10 may include multiple cylinders, such as a four-cylinder engine.

[0012] The intake flow path 12 includes an intake duct 30 and an intake manifold 32. An intake port 34 is provided at one end of the intake duct 30. The other end of the intake duct 30 is connected to the intake manifold 32. The intake manifold 32 has a base end portion 32A connected to the intake duct 30, from which multiple branch portions 32B extend. The multiple branch portions 32B of the intake manifold 32 are connected to the intake ports of each cylinder of the engine 10.

[0013] Air is introduced into the intake duct 30 through an intake port 34. The air introduced into the intake duct 30 is sent to an intake manifold 32. The intake manifold 32 introduces the air supplied through the intake duct 30 into the engine 10. For ease of explanation, the air introduced into the engine 10 may be referred to as intake air.

[0014] A throttle valve 36 is provided in the intake duct 30. The throttle valve 36 is capable of adjusting the amount of air supplied to the engine 10 through the intake passage 12.

[0015] The exhaust flow path 14 includes an exhaust duct 40 and an exhaust manifold 42. One end of the exhaust duct 40 is provided with an exhaust port 44. The other end of the exhaust duct 40 is connected to the exhaust manifold 42. The exhaust manifold 42 is connected to the exhaust ports of each cylinder of the engine 10.

[0016] The engine 10 discharges gas produced by the combustion of the air-fuel mixture as exhaust gas into the exhaust manifold 42. The exhaust manifold 42 sends the exhaust gas discharged from the engine 10 to the exhaust duct 40.

[0017] A purification device 46 capable of purifying the exhaust gas is provided in the exhaust duct 40. The exhaust gas purified by the purification device 46 is discharged to the outside through an exhaust port 44.

[0018] One end of the EGR passage 16 is connected to an exhaust duct 40 of the exhaust passage 14. The other end of the EGR passage 16 is connected to an intake duct 30 of the intake passage 12. The EGR passage 16 recirculates a portion of the exhaust gas of the engine 10 to the intake side of the engine 10.

[0019] An EGR valve 50 is provided in the EGR passage 16. The EGR valve 50 is capable of opening and closing the EGR passage 16.

[0020] The intake pressure sensor 18 is provided in the intake manifold 32. For example, the intake pressure sensor 18 may be provided in the base end portion 32A of the intake manifold 32. The intake pressure sensor 18 detects the pressure of the intake air inside the intake manifold 32. For ease of explanation, the pressure of the intake air may be referred to as the intake pressure.

[0021] The control device 20 has one or more processors 60 and one or more memories 62 connected to the processors 60. The memories 62 include a ROM in which programs and the like are stored and a RAM as a work area. The memory 62 may also include a storage in which programs and the like are stored. The processor 60 controls the entire vehicle 2 in cooperation with the programs stored in the memories 62 and the like.

[0022] For example, the processor 60 may execute a program to function as an engine control unit 70 that controls the engine 10. The engine control unit 70 can control, for example, the state of the engine 10, such as starting, driving, and stopping of the engine 10, and the engine rotation speed. The engine control unit 70 will be described in detail later.

[0023] The notification device 22 is, for example, a Malfunction Indicator Lamp (MIL) that can notify of an abnormality, etc. Note that the notification device 22 is not limited to a malfunction indicator lamp, and may be various display devices that can display the details of the abnormality, or sound output devices that can notify the details of the abnormality by sound.

[0024] 2 is a partial cross-sectional view showing an example of the configuration of the engine 10 according to this embodiment. The engine 10 has a cylinder block 100, a cylinder head 102, a piston 104, an intake valve 106, an exhaust valve 108, an injector 110, and an ignition plug 112.

[0025] A cylinder 120 is formed in the cylinder block 100. A cylinder head 102 is connected to the cylinder block 100 so as to cover the cylinder 120. A piston 104 is slidably housed inside the cylinder 120. The space surrounded by the cylinder 120, the cylinder head 102, and the piston 104 is a combustion chamber 122.

[0026] An intake port 130 and an exhaust port 132 are formed in the cylinder block 100. The intake port 130 is connected to the intake manifold 32. The exhaust port 132 is connected to the exhaust manifold 42.

[0027] The intake valve 106 is provided in the intake port 130. The intake valve 106 is capable of opening and closing the end of the intake port 130 on the combustion chamber 122 side. The exhaust valve 108 is provided in the exhaust port 132. The exhaust valve 108 is capable of opening and closing the end of the exhaust port 132 on the combustion chamber 122 side.

[0028] The injector 110 is disposed with its nozzle 140 facing the combustion chamber 122. The nozzle 140 of the injector 110 is located, for example, on the opposite side of the intake valve 106 from the exhaust valve 108. The injector 110 is capable of injecting fuel into the combustion chamber 122 through the nozzle 140.

[0029] The spark plug 112 is positioned so that the electrode 142 is exposed to the combustion chamber 122. The electrode 142 of the spark plug 112 is located, for example, between the intake valve 106 and the exhaust valve 108. The spark plug 112 is capable of igniting the air-fuel mixture in the combustion chamber 122 by generating a discharge at the electrode 142.

[0030] Next, we will explain the operation of engine 10 while it is warming up. While engine 10 is warming up, the temperature of engine 10 is still relatively low, so the fuel injected by injector 110 does not easily vaporize. As a result, the fuel injected by injector 110 tends to be concentrated in a certain region of combustion chamber 122, causing an imbalance in the concentration of the air-fuel mixture in combustion chamber 122.

[0031] During warm-up of the engine 10, when the intake valve 106 is opened and intake air is introduced into the combustion chamber 122, a gas flow occurs within the cylinder 120 as shown by the arrow A10 in FIG.

[0032] Region A12 in Fig. 2 shows an example of a region where the fuel injected by injector 110 is concentrated, i.e., a region where the concentration of the mixture is high. As shown in Fig. 2, the flow of gas within cylinder 120 sends the high-concentration mixture to the periphery of electrode 142 of spark plug 112. As a result, spark plug 112 ignites the high-concentration mixture, so ignition performance can be maintained even during warm-up of engine 10.

[0033] When deposits accumulate on intake valve 106 and intake port 130, the deposits block some of the air being introduced into cylinder 120, reducing the flow rate of air into cylinder 120. In other words, when deposits accumulate, the flow of gas within cylinder 120 slows down.

[0034] Figure 3 is a partial cross-sectional view showing an example of the operation of engine 10 during warm-up when the gas flow in cylinder 120 according to this embodiment is reduced. Arrow A20 in Figure 3 shows an example of the gas flow in cylinder 120 when the gas flow in cylinder 120 is reduced due to deposits. Region A22 in Figure 3 shows an example of a region where the fuel injected by injector 110 is concentrated, i.e., a region where the concentration of the air-fuel mixture is high.

[0035] When the gas flow in the cylinder 120 is reduced, the force that moves the mixture due to the gas flow is weakened, and it takes longer for the concentrated mixture to reach the area around the electrode 142 of the spark plug 112. As a result, as shown in FIG. 3, it becomes more difficult for the concentrated mixture to reach the area around the electrode 142 of the spark plug 112 before ignition by the spark plug 112. As a result, if the gas flow in the cylinder 120 is reduced due to deposits, ignition performance of the engine 10 may be reduced during warm-up.

[0036] As described above, when the gas flow in the cylinder 120 slows down, it takes longer for the concentrated air-fuel mixture to reach the area around the electrode 142 of the spark plug 112. Based on this, when the gas flow in the cylinder 120 slows down, one possible countermeasure is to relatively advance the fuel injection timing compared to before the gas flow in the cylinder 120 slowed down. In other words, by advancing the fuel injection timing, the time it takes for the concentrated air-fuel mixture to reach the area around the electrode 142 of the spark plug 112 is ensured, and the concentrated air-fuel mixture reaches the area around the electrode 142 of the spark plug 112 before ignition occurs.

[0037] However, it is difficult to directly detect the occurrence of a decrease in the gas flow in the cylinder 120 due to deposits.

[0038] For example, the flow velocity of air flowing into cylinder 120 can be detected if both the pressure inside intake manifold 32 (intake pressure) and the pressure inside cylinder 120 can be measured. However, measuring the pressure inside cylinder 120 for all cylinders of engine 10 is not realistic in terms of the durability and cost of the sensors required to achieve this.

[0039] From this perspective, it is difficult to grasp that a decrease in gas flow within cylinder 120 due to deposits has occurred, and it is also difficult to determine whether to take measures such as relatively advancing the fuel injection timing.

[0040] Therefore, in the engine system 1 of this embodiment, a first threshold value is prepared in advance. The first threshold value is determined based on the intake pressure at the first timing when the engine 10 is in an initial state and is undergoing rapid warm-up. The first timing will be described in detail later. The engine control unit 70 acquires the intake pressure at the first timing when the engine 10 is currently undergoing rapid warm-up using the intake pressure sensor 18. The engine control unit 70 determines whether the intake pressure measured by the intake pressure sensor 18 is lower than the first threshold value. If the engine control unit 70 determines that the intake pressure measured by the intake pressure sensor 18 is lower than the first threshold value, the engine control unit 70 executes an advancement process to relatively advance the fuel injection timing of the engine 10 according to the pressure difference between the first threshold value and the intake pressure measured by the intake pressure sensor 18.

[0041] Rapid warm-up is warming up the engine 10 by idling the engine 10 at an engine speed higher than the engine speed at normal idling. Rapid warm-up is also called fast idling.

[0042] Fig. 4 is an explanatory diagram showing the first timing according to this embodiment. As shown in Fig. 4, during the intake stroke of the engine 10, the piston 104 moves from a top dead center (TDC) at a crank angle of 0° toward a bottom dead center (BDC) at a crank angle of 180°.

[0043] As shown in FIG. 4, "IVO" is the intake valve opening timing that indicates the timing at which the intake valve 106 changes from a closed state to an open state. "IVC" is the intake valve closing timing that indicates the timing at which the intake valve 106 changes from an open state to a closed state. "IVO" may be set to, for example, a crank angle of approximately "15°." "IVC" may be set to, for example, a crank angle of approximately "270°."

[0044] A solid line B10 in Fig. 4 shows an example of the change in intake pressure in the intake manifold 32 of the engine 10 in an initial state (e.g., a new engine) where no deposits have accumulated on the intake valves 106, etc. A dashed-dotted line B12 in Fig. 4 shows an example of the change in intake pressure in the intake manifold 32 of the engine 10 in a current state (e.g., a state where deposits have accumulated on the intake valves 106, etc.).

[0045] The intake pressure in the engine 10 in the initial state starts to decrease from the point "IVO" and reaches a minimum value, for example, when the crank angle is near "90°." The crank angle "90°" is the midpoint between the top dead center and the bottom dead center of the piston 104 when the piston 104 moves toward the bottom dead center during the intake stroke of one cycle of the engine 10.

[0046] On the other hand, in the current state of engine 10, deposits act as resistance to the air flowing into cylinder 120. Therefore, as indicated by dashed-dotted line B12, in the current state of engine 10, the intake pressure starts to decrease later and the rate at which the intake pressure decreases is slower than in the initial state of engine 10.

[0047] As a result, at the time indicated by the notation "first timing" after "IVO" in Fig. 4, a difference occurs between the intake pressure in the engine 10 in the initial state (point C10 in Fig. 4) and the intake pressure in the engine 10 in the current state (point C12 in Fig. 4). By utilizing this difference, the engine system 1 of this embodiment determines that deposits have accumulated and determines whether to execute a fuel injection advancement process.

[0048] For ease of explanation, the period of one cycle of the engine 10 from the intake valve opening timing "IVO" until the piston 104 reaches bottom dead center "BDC" may be referred to as the first target section.

[0049] The first timing is included in this first target interval. Since the decrease in intake pressure begins after "IVO," a difference in intake pressure can occur after "IVO." The end point of the first target interval is the end of the intake stroke, and the first target interval is included in the intake stroke.

[0050] As described above, in the engine system 1 of this embodiment, the first timing is included in the first target section, so that the difference in intake pressure inside the intake manifold 32 can be detected appropriately.

[0051] Also, for ease of explanation, the period of one cycle of engine 10 that occurs after intake valve opening timing "IVO" and that ends when piston 104 moves in the direction toward bottom dead center "BDC" and reaches the midpoint between top dead center and bottom dead center (for example, crank angle "90°") may be referred to as the second target section.

[0052] It is more preferable that the first timing be included in this second target interval. After "IVO," a difference in intake pressure can occur. The first target interval is included in the intake stroke. The end point of the second target interval is the midpoint of the intake stroke. During the intake stroke, the amount of air flowing into cylinder 120 is greater in the first half of the intake stroke than in the second half of the intake stroke. Therefore, a difference in intake pressure is more likely to occur in the first half of the intake stroke.

[0053] In this way, in the engine system 1 of this embodiment, the first timing is included in the second target section, so that the difference in intake pressure inside the intake manifold 32 can be detected more appropriately.

[0054] As described above, in the engine system 1 of this embodiment, the first threshold value is prepared in advance and is determined by the intake pressure at the first timing during rapid warm-up of the engine 10 in an initial state. The first threshold value may be stored in advance in the memory 62 of the engine 10.

[0055] The first threshold value may be set during rapid warm-up of engine 10 in an initial state and substantially the same as the intake pressure at the first timing. Alternatively, the first threshold value may be set during rapid warm-up of engine 10 in an initial state and smaller by a predetermined value than the intake pressure at the first timing. The predetermined value may be set, for example, taking into account an allowable error.

[0056] The intake pressure at the first timing during rapid warm-up of the engine 10 in the initial state may be determined, for example, by an experiment or simulation using the engine 10 in a representative initial state.

[0057] The first threshold value may be prepared for each rotation speed of the engine 10. For example, the first threshold value may be stored in the memory 62 as a first threshold value table in which the rotation speed of the engine 10 and the first threshold value are associated with each other.

[0058] 5 is an explanatory diagram showing a modified example of the first timing according to the present embodiment. As shown in FIG. 5, "EVC" is the exhaust valve closing timing that indicates the timing at which the exhaust valve 108 changes from an open state to a closed state.

[0059] In the example of Fig. 5, the intake valve 106 changes to an open state before the exhaust valve 108 changes to a closed state. In other words, in the example of Fig. 5, one cycle of the engine 10 is controlled to include a valve overlap period in which both the intake valve 106 and the exhaust valve 108 are open.

[0060] For ease of explanation, when valve overlap is performed, the period of one cycle of the engine 10 that is after the intake valve opening timing "IVO" and after the exhaust valve closing timing "EVC" and until the piston 104 reaches bottom dead center "BDC" may be referred to as the third target section.

[0061] If valve overlap is performed during rapid warm-up, the first timing is included in this third target section. When valve overlap is performed, even after "IVO" but before "EVC," some of the gas in cylinder 120 flows out toward intake manifold 32, causing spit-back. If this spit-back occurs, the intake pressure in intake manifold 32 may differ from the desired value. For this reason, if valve overlap is performed, the first timing is included in the third target section, which excludes the section from "IVO" to "EVC."

[0062] In this way, in the engine system 1 of this embodiment, when valve overlap is performed, the first timing is included in the third target section, so it is possible to properly detect the difference in intake pressure within the intake manifold 32.

[0063] Also, for ease of explanation, when valve overlap is performed, the period of one cycle of engine 10 that is after intake valve opening timing "IVO" and after exhaust valve closing timing "EVC" and that ends when piston 104 reaches the midpoint between top dead center and bottom dead center (for example, crank angle "90°") as piston 104 moves in the direction toward bottom dead center "BDC" may be referred to as the fourth target period.

[0064] If valve overlap is performed during rapid warm-up, it is more preferable that the first timing be included in this fourth target interval. Setting the start point of the fourth target interval at "EVC" is essentially the same as setting the start point of the third target interval at "EVC." Also, setting the end point of the fourth target interval at "the midpoint between top dead center and bottom dead center" is essentially the same as setting the end point of the second target interval at "the midpoint between top dead center and bottom dead center."

[0065] In this way, in the engine system 1 of this embodiment, when valve overlap is performed, the first timing is included in the fourth target section, making it possible to more appropriately detect the difference in intake pressure within the intake manifold 32.

[0066] 6, 7, and 8 are flowcharts showing the flow of operations of the engine control unit 70 according to this embodiment. "A" in Fig. 6 connects to "A" in Fig. 7. "B" in Fig. 6 connects to "B" in Fig. 8.

[0067] As shown in FIG. 6, when the start conditions for the engine 10 are met, the engine control unit 70 starts the engine 10 (S10). After the engine 10 starts, the engine control unit 70 determines whether an advance flag is on (S11). The advance flag is an index used to determine whether or not to execute a fuel injection advance process. If the advance flag is on, the fuel injection advance process is performed as described below. The advance process is a process for relatively advancing the fuel injection timing in the engine 10 compared to normal injection control.

[0068] If it is determined that the advance flag is on (YES in S11), the engine control unit 70 proceeds to the process of "B" in FIG.

[0069] If it is determined that the advance flag is off (NO in S11), the engine control unit 70 determines whether an initial learned value of the rotational fluctuation of the engine 10 is stored in the memory 62 (S12). The rotational fluctuation of the engine 10 is an index that indicates the deviation of the actual rotational speed from the target rotational speed of the engine 10. The rotational fluctuation of the engine 10 varies from engine to engine. For this reason, as will be described later, the initial state of the engine rotational fluctuation is learned for each individual engine.

[0070] If it is determined that an initial learned value of the rotational fluctuation is already present (YES in S12), the engine control unit 70 proceeds to "A" in FIG.

[0071] If it is determined that the initial learned value of the rotational fluctuation has not yet been stored (NO in S12), the engine control unit 70 determines whether or not the conditions for performing rapid warm-up are met in the current start (S13). For example, the engine control unit 70 may determine that the conditions for rapid warm-up are met if the engine is in a cold state at the time of start.

[0072] If it is determined that the conditions for performing rapid warm-up are not met (NO in S13), the engine control unit 70 performs normal fuel injection control (S14). In this case, rapid warm-up is not performed, and normal fuel injection according to the target rotation speed is performed.

[0073] The engine control unit 70 continues the normal injection control (S14) while it has not received an engine stop command (NO in S15). When it receives an engine stop command (YES in S15), the engine control unit 70 stops the engine 10 (S16) and ends the current engine control.

[0074] On the other hand, if it is determined that the conditions for performing rapid warm-up are met (YES in S13), the engine control unit 70 performs rapid warm-up (S20). That is, the engine 10 is warmed up by idling at a relatively high engine speed.

[0075] When rapid warm-up is performed (S20), the engine control unit 70 determines the rotation fluctuation of the engine 10 during the rapid warm-up as an initial learned value (S21). For example, the engine control unit 70 may calculate the rotation fluctuation based on the target rotation speed and the actual rotation speed at each of a plurality of points in time during the rapid warm-up, and determine the initial learned value by comprehensively evaluating the rotation fluctuation at each point in time.

[0076] The engine control unit 70 stores the identified initial learned value in the memory 62 (S22), and proceeds to "A" in Fig. 7. As a result, the next time the engine is started, it will be determined in the processing of step S12 that the initial learned value of the rotation fluctuation has already been determined.

[0077] The engine 10 in an initial state (e.g., a new product) is started, for example, during inspection at the time of manufacturing the vehicle 2. Therefore, the initial learning values ​​are identified and stored for each individual engine 10 in the engine 10 that is substantially in an initial state (e.g., a new product).

[0078] The condition for specifying and storing the initial learned value is not limited to the condition for rapid warm-up, and various conditions may be added in addition to the condition for rapid warm-up.

[0079] 7, the engine control unit 70 acquires various data related to the engine 10 (S30). For example, the engine control unit 70 may acquire the detected value of the intake pressure sensor 18 of the intake manifold 32. Note that the acquired data is not limited to the detected value of the intake pressure sensor 18, and may be various data that can be used in subsequent processing, etc.

[0080] Next, the engine control unit 70 determines whether or not the conditions for performing rapid warm-up are met in the current start (S31). For example, the engine control unit 70 may determine that the conditions for rapid warm-up are met if the engine 10 is in a cold state at the time of start-up.

[0081] If it is determined that the conditions for performing rapid warm-up are met (YES in S31), the engine control unit 70 performs rapid warm-up (S32). That is, the engine 10 is warmed up by idling at a relatively high engine speed.

[0082] When the rapid warm-up is performed (S32), the engine control unit 70 determines whether or not a predetermined auxiliary condition is satisfied (S33).

[0083] The predetermined auxiliary condition may include one or more of the following: (1) a first auxiliary condition, (2) a second auxiliary condition, (3) a third auxiliary condition, and (4) a fourth auxiliary condition.

[0084] (1) The first auxiliary condition includes the execution of fuel cut control in the engine 10. The fuel cut control is a control that does not perform fuel injection when, for example, the accelerator operation amount is "0" and the vehicle is traveling downhill.

[0085] (2) The second auxiliary condition includes that the water temperature of the engine 10 is equal to or higher than a predetermined temperature. The predetermined temperature may be set to, for example, 90°C.

[0086] (3) The third auxiliary condition includes that the rotation speed of the engine 10 is within a predetermined range. The predetermined range may be set to, for example, 1200 rpm to 2400 rpm.

[0087] (4) The fourth auxiliary condition includes a state in which the EGR valve 50, which can open and close the EGR passage 16, is closed. In other words, the fourth auxiliary condition includes a state in which a portion of the exhaust gas of the engine 10 is not recirculated to the intake side of the engine 10.

[0088] If it is determined that the auxiliary condition is not satisfied (NO in S33), engine control unit 70 proceeds to the process of step S40.

[0089] If it is determined that the auxiliary condition is satisfied (YES in S33), the engine control unit 70 determines whether the current time is substantially the first timing (S34). Note that being substantially the first timing is not limited to the current time completely coinciding with the first timing, but may also include the current time being close to the first timing within a predetermined allowable error range.

[0090] If it is determined that the current time is not substantially the first timing (NO in S34), the engine control unit 70 proceeds to the process of step S40.

[0091] If it is determined that the current time is substantially the first timing (YES in S34), the engine control unit 70 determines whether the intake pressure measured by the intake pressure sensor 18 in step S30 is smaller than a first threshold value (S35). Since it is determined that the current time is the first timing, the intake pressure measured by the intake pressure sensor 18 in step S30 is substantially the intake pressure measured by the intake pressure sensor 18 at the first timing.

[0092] For example, the engine control unit 70 refers to the current engine speed acquired in step S30 and the first threshold value table stored in the memory 62, and reads out the first threshold value corresponding to the current engine speed acquired in step S30. The engine control unit 70 may compare the intake pressure measured by the intake pressure sensor 18 acquired in step S30 with the read-out first threshold value.

[0093] If it is determined that the intake pressure detected by the intake pressure sensor is equal to or greater than the first threshold value (NO in S35), the engine control unit 70 proceeds to the process of step S40.

[0094] If it is determined that the intake pressure measured by the intake pressure sensor 18 is lower than the first threshold value (YES in S35), it can be inferred that the flow in the cylinder has decreased due to deposits on the intake valve or the like, and the engine control unit 70 turns on the advancement flag (S36). By turning on the advancement flag, it becomes possible to execute the fuel injection advancement process the next time the engine is started. After turning on the advancement flag, the engine control unit 70 proceeds to the process of step S40.

[0095] Furthermore, in step S31, if it is determined that the conditions for performing rapid warm-up are not met (NO in S31), the engine control unit 70 performs normal injection control (S37) and proceeds to the processing of step S40. In this case, rapid warm-up is not performed, and normal fuel injection according to the target rotation speed is performed.

[0096] In step S40, if engine control unit 70 has not received an engine stop instruction (NO in S40), it returns to the process of step S30 and repeats the process.

[0097] When the engine stop command is received (YES in S40), the engine control unit 70 stops the engine 10 (S41) and ends the current engine control.

[0098] In the above description, the advance flag is turned on (S36) when it is determined that the auxiliary condition is satisfied (YES in S33) and when it is determined that the intake pressure measured by the intake pressure sensor 18 is lower than the first threshold value (YES in S34). However, the determination of the auxiliary condition (S33) may be omitted, and the advance flag may be turned on at least when it is determined that the intake pressure measured by the intake pressure sensor 18 is lower than the first threshold value (YES in S34).

[0099] When the process proceeds to "B" in FIG. 8, the engine control unit 70 acquires various data related to the engine 10 (S50). For example, the engine control unit 70 may acquire the detected value of the intake pressure sensor 18 of the intake manifold 32. Note that the acquired data is not limited to the detected value of the intake pressure sensor 18, and may be various data that can be used in subsequent processing, etc.

[0100] Next, the engine control unit 70 determines whether or not the conditions for performing rapid warm-up are met in the current start (S51). For example, the engine control unit 70 may determine that the conditions for rapid warm-up are met if the engine 10 is in a cold state at the time of start-up.

[0101] If it is determined that the conditions for performing rapid warm-up are met (YES in S51), the engine control unit 70 performs rapid warm-up (S52). That is, the engine 10 is warmed up by idling at a relatively high engine speed.

[0102] When rapid warm-up is performed (S52), the engine control unit 70 determines whether the current time is substantially the first timing (S53). Note that being substantially the first timing does not necessarily mean that the current time is exactly the first timing, but may also mean that the current time is close to the first timing within a predetermined allowable error range.

[0103] If it is determined that the current time is not substantially the first timing (NO in S53), engine control unit 70 proceeds to the process of step S80.

[0104] If it is determined that the current time is substantially the first timing (YES in S53), the engine control unit 70 calculates the pressure difference between the first threshold value and the intake pressure measured by the intake pressure sensor and acquired in step S50 (S54).

[0105] For example, the engine control unit 70 refers to the current engine speed acquired in step S50 and the first threshold value table stored in the memory 62, and reads out the first threshold value corresponding to the current engine speed acquired in step S50. The engine control unit 70 may calculate the pressure difference by subtracting the intake pressure measured by the intake pressure sensor 18 acquired in step S50 from the read first threshold value.

[0106] Based on the calculated pressure difference, the engine control unit 70 sets the timing of fuel injection by the injector 110 (S55). That is, the degree to which fuel injection should be advanced is set according to the pressure difference.

[0107] Then, the engine control unit 70 advances the fuel injection in accordance with the set injection timing (S56).

[0108] Next, the engine control unit 70 sets a second threshold value for the rotation fluctuation of the engine 10 based on the initial learned value of the rotation fluctuation of the engine 10 stored in the memory 62 (S57). For example, the engine control unit 70 may set the second threshold value by adding a predetermined value representing an allowable error to the initial learned value. Since the initial learned value of the rotation fluctuation is specific to each individual engine 10, the second threshold value is also set for each individual engine 10.

[0109] After setting the second threshold value (S57), the engine control unit 70 determines whether the rotation fluctuation at the current time when the fuel injection advancement is being performed exceeds the second threshold value (S60). If it is determined that the rotation fluctuation at the current time when the fuel injection advancement is being performed is within the second threshold value (NO in S60), the engine control unit 70 proceeds to the process of step S80.

[0110] If it is determined that the rotational fluctuation at the time when fuel injection advancement is being performed exceeds the second threshold, engine control unit 70 causes the alarm device to notify that the gas flow inside cylinder 120 has decreased beyond the allowable range (S61). That is, even if the fuel injection advancement measure is taken, it is presumed that the gas flow inside cylinder 120 has decreased further, so by causing the alarm device to notify, inspection or maintenance of engine 10 by a specialist is encouraged. After causing the alarm device to notify, engine control unit 70 proceeds to the processing of step S80.

[0111] Furthermore, in step S51, if it is determined that the conditions for performing rapid warm-up are not met (NO in S51), the engine control unit 70 performs normal injection control (S70) and proceeds to the processing of step S80. In this case, rapid warm-up is not performed, and normal fuel injection according to the target rotation speed is performed.

[0112] In step S80, if engine control unit 70 has not received an engine stop instruction (NO in S80), the process returns to step S50 and repeats the process.

[0113] When the engine stop command is received (YES in S80), the engine control unit 70 stops the engine 10 (S81) and ends the current engine control.

[0114] In the above description, the degree of fuel injection advancement is set according to the pressure difference as shown in step S55. However, the degree of fuel injection advancement may be a value prepared in advance. In this case, for example, an advancement degree table in which the engine speed and the degree of fuel injection advancement are associated with each other, like the first threshold value table, may be stored in advance in the memory 62. The engine control unit 70 may set the degree of fuel injection advancement by referring to the current engine speed and the advancement degree table.

[0115] As described above, in the engine system 1 of this embodiment, the engine 10 is in an initial state during rapid warm-up, and a first threshold value determined by the intake pressure at the first timing is prepared in advance. The first timing of the engine system 1 is after the intake valve open timing, which represents the timing at which the intake valve 106 changes from a closed state to an open state, within one cycle of the engine 10, and is included in the period until the piston 104 reaches bottom dead center. The processor 60 of the engine system 1 acquires the intake pressure at the first timing from the intake pressure sensor 18 during rapid warm-up in the engine 10 in its current state. The processor 60 of the engine system 1 determines whether the intake pressure measured by the intake pressure sensor 18 is lower than the first threshold value. If the processor 60 of the engine system 1 determines that the intake pressure measured by the intake pressure sensor 18 is lower than the first threshold value, the processor 60 executes an advancement process to relatively advance the fuel injection timing of the engine 10 in accordance with the pressure difference between the first threshold value and the intake pressure measured by the intake pressure sensor 18.

[0116] As a result, the engine system 1 of this embodiment can substantially recognize that a decrease in the gas flow in the cylinder 120 has occurred due to deposits accumulating on the intake valve 106 or the like. The engine system 1 of this embodiment can advance the fuel injection timing in response to the occurrence of a decrease in the gas flow in the cylinder 120 due to deposits accumulating on the intake valve 106 or the like. As a result, the engine system 1 of this embodiment can ensure that a highly concentrated air-fuel mixture reaches the periphery of the electrode 142 of the spark plug 112 by the time of ignition, even if the gas flow in the cylinder 120 has decreased.

[0117] Therefore, according to the engine system 1 of this embodiment, even if deposits accumulate on the intake valve 106 or the like, it is possible to suppress a decrease in ignition performance.

[0118] While the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention.

[0119] It should be noted that the processes shown in this specification do not necessarily have to be performed in chronological order according to the order shown in the flowcharts, and may include parallel or subroutine processes. [Explanation of symbols]

[0120] 1 Engine System 10 Engine 16 EGR passage 18 Intake pressure sensor 20 Control device 22 Alarm device 32 intake manifold 50 EGR valve 60 processors 62 memory 104 Piston 120 cylinders 106 Intake valve 108 Exhaust valve

Claims

1. an engine having a piston, a cylinder, an intake valve, and an exhaust valve; an intake manifold that introduces intake air into the engine; an intake pressure sensor that detects an intake pressure inside the intake manifold; a control device for controlling the engine; Equipped with The control device one or more processors; one or more memories coupled to the processor; and a first threshold value is prepared in advance, the first threshold value being determined by the intake pressure at a first timing during rapid warm-up in the engine in an initial state; the first timing is after an intake valve opening timing, which indicates a timing at which the intake valve changes from a closed state to an open state, during one cycle of the engine, and is included in a period before the piston reaches bottom dead center; The processor: In the engine in a current state, the engine is undergoing rapid warm-up and the intake pressure at the first timing is acquired by the intake pressure sensor; determining whether the intake pressure detected by the intake pressure sensor is smaller than the first threshold value; when it is determined that the intake pressure measured by the intake pressure sensor is smaller than the first threshold value, executing an advancement process to relatively advance a fuel injection timing in the engine in accordance with a pressure difference between the first threshold value and the intake pressure measured by the intake pressure sensor; An engine system that performs processing including:

2. 2. The engine system according to claim 1, wherein the first timing is a timing that occurs after the intake valve opening timing during one cycle of the engine and is included in a period during which the piston reaches a midpoint between top dead center and bottom dead center as the piston moves in a direction toward bottom dead center.

3. 2. The engine system according to claim 1, wherein, when valve overlap is performed during the rapid warm-up, the first timing is, within one cycle of the engine, after the intake valve opening timing, after exhaust valve closing timing that represents the timing at which the exhaust valve changes from an open state to a closed state, and is included in the period until the piston reaches bottom dead center.

4. The processor: when it is determined that the auxiliary condition is satisfied and the intake pressure measured by the intake pressure sensor is smaller than the first threshold value, executing the advancement process in accordance with the pressure difference; Perform a process including The auxiliary conditions include at least one of the following: a fuel cut control is being executed in the engine; a water temperature of the engine is equal to or higher than a predetermined temperature; a rotation speed of the engine is within a predetermined range; and an EGR valve capable of opening and closing an EGR flow path that recirculates a portion of the exhaust gas of the engine to the intake side of the engine is in a closed state. The engine system of claim 1 .

5. The processor: specifying, for each of the engines, a rotational fluctuation of the engine during rapid warm-up in an initial state of the engine as an initial learned value; setting a second threshold value of the engine rotation fluctuation based on the initial learned value; When the accelerating process is executed, determining whether or not a rotation fluctuation of the engine during the accelerating process exceeds the second threshold value; When it is determined that the rotational fluctuation of the engine during the execution of the accelerating process exceeds the second threshold value, a predetermined notification device is caused to notify that the gas flow inside the cylinder has decreased beyond an allowable range. The engine system of claim 1 , wherein the engine system performs a process including:

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