Engine equipment

Abstract

To inhibit an air-fuel ratio from becoming lean when performing switching from a state where an engine is operated by injecting fuel from a cylinder injection valve in the latter half of a compression stroke to a state where the engine is operated by injecting fuel from the cylinder injection valve before the compression stroke.SOLUTION: An engine device includes: an engine having a cylinder injection valve; and a control device that controls the engine. The control device executes predetermined fuel amount increase control for increasing a fuel injection amount when switching is performed from a first fuel injection operating state where the engine is operated by injecting fuel from the cylinder injection valve in the latter half of a compression stroke to a second fuel injection operating state where the engine is operated by injecting fuel from the cylinder injection valve before the compression stroke.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an engine device, and more particularly to an engine device including an engine having a direct injection valve. [Background technology]

[0002] Conventionally, as an engine device of this type, one that has an in-cylinder injection valve and is equipped with an engine supplied with fuel containing alcohol has been proposed (see, for example, Patent Document 1). In this device, during a cold start when the engine temperature is below a predetermined temperature, fuel is injected from the in-cylinder injection valve in the latter half of the compression stroke to start the engine, and then the timing of fuel injection from the in-cylinder injection valve is advanced to improve the startability of the engine when it is cold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-224621 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned engine device, when the engine is switched from operating with fuel injected from the in-cylinder injection valve in the latter half of the compression stroke to operating with fuel injected from the in-cylinder injection valve before the compression stroke, the air-fuel ratio may become lean.When the fuel injection is switched from the latter half of the compression stroke to operating with fuel injected before the compression stroke (intake stroke), fuel adheres to the cylinder wall surface and the piston top surface, reducing the amount of fuel that contributes to combustion and causing the air-fuel ratio to become lean.

[0005] The engine device of the present disclosure has a primary objective of preventing the air-fuel ratio from becoming lean when switching from a state in which the engine is operated by injecting fuel from the in-cylinder injection valve in the latter half of the compression stroke to a state in which the engine is operated by injecting fuel from the in-cylinder injection valve before the compression stroke. [Means for solving the problem]

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

[0007] The engine device of the present disclosure comprises: An engine device comprising an engine having an in-cylinder injection valve and a control device that controls the engine, the control device executes a predetermined fuel increase control to increase the fuel injection amount when switching from a first fuel injection operating state in which the engine is operated by injecting fuel from the in-cylinder injection valve in the latter half of the compression stroke to a second fuel injection operating state in which the engine is operated by injecting fuel from the in-cylinder injection valve before the compression stroke. It is characterized by:

[0008] In the engine device disclosed herein, when switching from a first fuel injection operating state in which the engine is operated by injecting fuel from the in-cylinder injection valve in the latter half of the compression stroke to a second fuel injection operating state in which the engine is operated by injecting fuel from the in-cylinder injection valve before the compression stroke, a predetermined fuel increase control is executed to increase the fuel injection amount. Increasing the fuel injection amount can prevent the air-fuel ratio from becoming lean. As a result, when switching from a state in which the engine is operated by injecting fuel from the in-cylinder injection valve in the latter half of the compression stroke to a state in which the engine is operated by injecting fuel from the in-cylinder injection valve before the compression stroke, the air-fuel ratio can be prevented from becoming lean.

[0009] In the engine system of the present disclosure, the control device may execute the predetermined fuel increase control when the cylinder wall temperature or piston top temperature of the engine is below a threshold temperature. The switching from the first fuel injection operating state to the second fuel injection operating state is based on the fact that it occurs when the engine and / or catalyst have warmed up to a certain extent. Here, the threshold temperature may be the boiling temperature of the fuel or a temperature slightly lower than that. In this case, the control device may use a temperature based on the ethanol concentration of the fuel as the threshold temperature. It is preferable that the threshold temperature be set so that it decreases as the ethanol concentration of the fuel increases. This is based on the fact that the boiling temperature of the fuel decreases as the ethanol concentration of the fuel increases.

[0010] The engine system of the present disclosure may include a port injection valve, and the control device may adjust the fuel increase value in the predetermined fuel increase control based on fuel injection modes of the port injection valve and the direct injection valve. Examples of fuel injection modes include whether or not fuel is injected from the port injection valve and the number of fuel injections from the direct injection valve. When fuel is injected from the port injection valve, the fuel increase value is preferably adjusted to decrease as the distribution ratio of the fuel injection amount from the port injection valve increases. This is based on the fact that the larger the distribution ratio of the fuel injection amount from the port injection valve, the easier the fuel is to atomize and the less likely the fuel is to adhere to the cylinder wall surface and the top surface of the piston of the engine. Furthermore, the fuel increase value is preferably adjusted to decrease as the number of fuel injections from the direct injection valve increases. This is based on the fact that the more fuel is injected from the direct injection valve, the easier the fuel is to atomize and the less likely the fuel is to adhere to the cylinder wall surface and the top surface of the piston.

[0011] In the engine system of the present disclosure, the control device may adjust the fuel increase value based on the engine coolant temperature and the ethanol concentration of the fuel. Preferably, the fuel increase value is adjusted so that it increases as the engine coolant temperature decreases and as the ethanol concentration of the fuel increases. This is based on the fact that the lower the engine coolant temperature or the higher the ethanol concentration of the fuel, the easier the fuel is to atomize and the less likely the fuel is to adhere to the cylinder wall surface and the top surface of the piston.

[0012] In the engine system of the present disclosure, the control device may adjust the fuel increase value based on the fuel injection timing from the direct injection valve in the second fuel injection operating state. The relationship between the fuel injection timing and the fuel increase value may be determined based on the results of experiments, machine learning, or the like. In this case, when fuel is injected multiple times from the direct injection valve in the second fuel injection operating state, it is preferable that the control device adjusts the fuel increase value based on the timing of a first fuel injection.

[0013] In the engine apparatus of the present disclosure, the predetermined fuel increase control is preferably executed until fuel is injected into at least all cylinders of the engine, and during that time, the fuel increase value is adjusted based on the fuel injection timing of each cylinder.Furthermore, the predetermined fuel increase control is preferably controlled to maintain the fuel increase value at the start of control from the start of control until fuel is injected into all cylinders of the engine, and thereafter attenuate the fuel increase value. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a configuration diagram showing an outline of the configuration of an engine device 10 according to an embodiment of the present invention. [Figure 2] 4 is a flowchart showing an example of a fuel increase process executed by an electronic control unit 70 according to the embodiment. [Figure 3] FIG. 2 is an explanatory diagram showing an example of the relationship between the ethanol concentration Cet in fuel and the threshold temperature Tref. [Figure 4] FIG. 4 is an explanatory diagram showing an example of the relationship between a port injection distribution ratio and a fuel increase value Qadd. [Figure 5] 4 is an explanatory diagram showing an example of the relationship between the number of fuel injections of the direct injection valve 26 and a fuel increase value Qadd. FIG. [Figure 6] 3 is an explanatory diagram showing an example of the relationship between the coolant temperature Tw of the engine 12, the ethanol concentration Cet in the fuel, and the fuel increase value Qadd. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Next, a mode (embodiment) for carrying out the present disclosure will be described. Fig. 1 is a configuration diagram showing an outline of the configuration of an engine device 10 according to an embodiment of the present disclosure. As shown in the figure, the engine device 10 of the embodiment includes an engine 12, a fuel supply device 50, and an electronic control unit 70. The engine device 10 is mounted on a general vehicle that runs using power from the engine 12, various hybrid vehicles that include a motor in addition to the engine 12, and stationary equipment (such as construction equipment) that operates using power from the engine 12.

[0016] The engine 12 is configured as an internal combustion engine that uses fuel such as gasoline or a mixture of gasoline and alcohol, and outputs power through four strokes: intake, compression, expansion, and exhaust. The engine 12 is equipped with a port injection valve 25 that injects fuel into the intake port, and an in-cylinder injection valve 26 that injects fuel into the cylinder. By being equipped with the port injection valve 25 and the in-cylinder injection valve 26, the engine 12 can be operated in any of a port injection mode, an in-cylinder injection mode, and a common injection mode.

[0017] In the port injection mode, air purified by the air cleaner 22 is drawn into the intake pipe 23 and passes through the throttle valve 24, while fuel is injected from the port injection valve 25 to mix the air and fuel. This mixture is drawn into the combustion chamber 29 via the intake valve 28 and is explosively combusted by an electric spark from the spark plug 30. The reciprocating motion of the piston 32, which is pushed down by the energy from the explosive combustion, is then 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 29, and fuel is injected from the direct injection valve 26 midway through the intake stroke and / or during the compression stroke, and is explosively combusted by an electric spark from the spark plug 30 to rotate the crankshaft 14. In the shared injection mode, fuel is injected from the port injection valve 25 when air is drawn into the combustion chamber 29, and fuel is injected from the in-cylinder injection valve 26 during the intake stroke and the compression stroke, and the fuel is explosively burned by an electric spark from the spark plug 30, generating rotational motion of the crankshaft 14. These injection modes are switched depending on the operating state of the engine 12. Exhaust gas discharged from the combustion chamber 29 into the exhaust pipe 33 via the exhaust valve 31 is discharged into the outside air via a purification device 34 having a purification catalyst (three-way catalyst) 34a that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx).

[0018] The fuel supply device 50 is configured as a device that supplies fuel in a fuel tank 51 to the port injection valves 25 and the in-cylinder injection valves 26 of the engine 12. The fuel supply device 50 includes the fuel tank 51, a feed pump (first pump) 52, a low-pressure supply pipe (first supply pipe) 53, a check valve 54, a relief flow path 55, a relief valve 56, a high-pressure pump (second pump) 57, and a high-pressure supply pipe (second supply pipe) 58.

[0019] Feed pump 52 is configured as an electric pump that operates by receiving power from a battery (not shown), and is disposed inside fuel tank 51. Feed pump 52 supplies fuel from inside fuel tank 51 to low-pressure supply pipe 53. Low-pressure supply pipe 53 is connected to port injection valve 25. Check valve 54 is provided in low-pressure supply pipe 53 and allows fuel to flow in the direction from feed pump 52 to port injection valve 25, while restricting fuel flow in the opposite direction.

[0020] The relief flow passage 55 is connected to the low-pressure supply pipe 53 and the fuel tank 51. The relief valve 56 is provided in the relief flow passage 55, and closes when the fuel pressure in the low-pressure supply pipe 53 is below a threshold value Pflolim, and opens when the fuel pressure in the low-pressure supply pipe 53 is equal to or higher than the threshold value Pflolim. When the relief valve 56 opens, a portion of the fuel in the low-pressure supply pipe 53 is returned to the fuel tank 51 via the relief flow passage 55. In this way, the fuel pressure in the low-pressure supply pipe 53 is prevented from becoming excessive.

[0021] The high-pressure pump 57 is driven by power from the engine 12 (in this embodiment, rotation of the intake camshaft that opens and closes the intake valve 28), and is configured as a pump that pressurizes fuel in the low-pressure supply pipe 53 and supplies it to the high-pressure supply pipe 58. The high-pressure pump 57 has an electromagnetic valve 57a connected to its intake port that opens and closes when pressurizing the fuel, a check valve 57b connected to its discharge port that regulates backflow of fuel and maintains the fuel pressure in the high-pressure supply pipe 58, and a plunger 57c that is actuated (moves vertically in FIG. 1 ) by the rotation of the engine 12 (rotation of the intake camshaft). During operation of the engine 12, when the electromagnetic valve 57a is open, the high-pressure pump 57 sucks fuel from the low-pressure supply pipe 53, and when the electromagnetic valve 57a is closed, the high-pressure pump 57 pressurizes the fuel to be supplied to the high-pressure supply pipe 58 by intermittently sending fuel compressed by the plunger 57c into the high-pressure supply pipe 58 via the check valve 57b. When the high-pressure pump 57 is driven, the fuel pressure in the low-pressure supply pipe 53 and the fuel pressure (fuel pressure) in the high-pressure supply pipe 58 pulsate in accordance with the rotation of the engine 12 (the rotation of the intake camshaft). The high-pressure supply pipe 58 is connected to the in-cylinder injection valve 26.

[0022] The electronic control unit 70 includes a microcomputer having a CPU 71, ROM 72, RAM 73, flash memory 74, and input / output ports. Signals from various sensors are input to the electronic control unit 70 via the input ports. Examples of signals input to the electronic control unit 70 include a crank angle θcr from a crank position sensor 14a that detects the rotational position of the crankshaft 14 of the engine 12, and a coolant temperature Tw from a water temperature sensor 40 that detects the temperature of the coolant for the engine 12. Other examples of signals input to the electronic control unit 70 include cam angles θci and θco from a cam position sensor 44 that detects the rotational position of an intake camshaft that opens and closes the intake valve 28 and the rotational position of an exhaust camshaft that opens and closes the exhaust valve 31. Other examples include the throttle opening TH from a throttle position sensor 24a that detects the position of the throttle valve 24, the intake air amount Qa from an air flow meter 23a attached upstream of the throttle valve 24 in the intake pipe 23, and the intake air temperature Ta from a temperature sensor 23t attached upstream of the throttle valve 24 in the intake pipe 23. Other examples include the air-fuel ratio AF from an air-fuel ratio sensor 35 attached upstream of the purification device 34 in the exhaust pipe 33, and an oxygen signal O2 from an oxygen sensor 36 attached downstream of the purification device 34 in the exhaust pipe 33. Other examples include the fuel temperature Tftnk from a fuel temperature sensor 51t attached to the fuel tank 51, the rotation speed Nlp of the feed pump 52 from a rotation speed sensor 52a attached to the feed pump 52, the low-pressure fuel pressure (the pressure of the fuel supplied to the port injection valve 25) Pflo from a fuel pressure sensor 53p attached to the low-pressure supply pipe 53 near the port injection valve 25 (e.g., the low-pressure delivery pipe), and the high-pressure fuel pressure (the pressure of the fuel supplied to the in-cylinder injection valve 26) Pfhi from a fuel pressure sensor 58p attached to the high-pressure supply pipe 58 near the in-cylinder injection valve 26 (e.g., the high-pressure delivery pipe).

[0023] Various control signals are output from the electronic control unit 70 via the output port. Examples of signals output from the electronic control unit 70 include a control signal to the throttle valve 24 of the engine 12, a control signal to the port injection valve 25, a control signal to the in-cylinder injection valve 26, and a control signal to the spark plug 30. Other examples include a control signal to the feed pump 52 of the fuel supply device 50 and a control signal to the electromagnetic valve 57a of the high-pressure pump 57.

[0024] The electronic control unit 70 calculates the rotation speed Ne of the engine 12 based on the crank angle θcr from the crank position sensor 14a. The electronic control unit 70 also calculates a 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) based on the intake air amount Qa from the air flow meter 23a and the rotation speed Ne of the engine 12. The electronic control unit 70 also estimates the temperature Tc of the catalyst 34a of the purification device 34 based on the coolant temperature Tw from the water temperature sensor 40, the rotation speed Ne of the engine 12, and the load factor KL. In addition, the electronic control unit 70 estimates the fuel temperature Tfhp in the high-pressure pump 57 based on the coolant temperature Tw from the temperature sensor 40 and the intake air temperature Ta from the temperature sensor 23t. In addition, the electronic control unit 70 estimates the temperature Tcyl of the wall surface (cylinder wall surface) of the combustion chamber 29 and the temperature Ttop of the top surface of the piston 32 based on the cooling water temperature Tw from the water temperature sensor 40, the intake air temperature Ta from the temperature sensor 23t, and the integrated value of the intake air volume after the engine 12 is started.

[0025] In the engine device 10 of this embodiment configured as described above, the CPU 71 of the electronic control unit 70 controls the intake air volume, fuel injection, and ignition of the engine 12 as part of the operation control of the engine 12, and also controls the feed pump 52 and high-pressure pump 57 (electromagnetic valve 57a) of the fuel supply device 50.

[0026] For example, the intake air amount control of the engine 12 involves setting a required air amount Qa* based on the accelerator pedal position and the engine speed Ne of the engine 12, setting a target opening TH* of the throttle valve 24 so that the intake air amount Qa becomes the required air amount Qa*, and controlling the throttle valve 24 using the target opening TH*. For fuel injection control of the engine 12, a basic fuel injection amount Qbase is set based on the required air amount Qa* and the target air-fuel ratio AF*, and a fuel increase value Qadd is set as needed, and a required injection amount Qfuel* is set as the sum of the basic fuel injection amount Qbase and the fuel increase value Qadd. Then, based on the injection mode and the required injection amount Qfuel*, the fuel injection time Tp from the port injection valve 25 and the number of injections from the direct injection valve 26 and each fuel injection time Tf(n) are set, and the start times Tp and Tf of each fuel injection are set. The port injection valve 25 and the direct injection valve 26 are controlled to open so that fuel is injected at the start times Tp and Tf for the fuel injection times Tp and Tf(n). Ignition control of the engine 12 involves setting a target ignition timing Ti* for the spark plug 30 based on the engine speed Ne, required air amount Qa*, etc., of the engine 12, and controlling the spark plug 30 using the set target ignition timing Ti*.

[0027] Next, the operation of the engine device 10 of the embodiment configured as described above will be described, particularly the operation of adjusting the fuel injection amount when switching from a state in which the engine 12 is operated by injecting fuel from the direct injection valve 25 in the latter half of the compression stroke (first fuel injection operating state) to a state in which the engine 12 is operated by injecting fuel from the direct injection valve 25 before the compression stroke (intake stroke) (second fuel injection operating state). The first fuel injection operating state is the operating state of the engine 12 when the engine 12 and the catalyst are warming up, and the second fuel injection operating state is the operating state of the engine 12 after the engine 12 and the catalyst have been warmed up to a certain extent. Therefore, the following will describe the operation of adjusting the fuel injection amount when the operating state of the engine 12 is switched from the first fuel injection operating state to the second fuel injection operating state after the engine 12 and the catalyst have been warmed up to a certain extent.

[0028] 2 is a flowchart showing an example of a fuel increase process executed by the electronic control unit 70 when switching from the first fuel injection operating state to the second fuel injection operating state. When the fuel increase process is executed, the electronic control unit 70 first determines whether the operation is switching from a state in which the engine 12 is operated by injecting fuel from the direct injection valve 25 in the latter half of the compression stroke (first fuel injection operating state) to a state in which the engine 12 is operated by injecting fuel from the direct injection valve 25 before the compression stroke (intake stroke) (second fuel injection operating state) (step S100). If it is determined that the operation is not switching from the first fuel injection operating state to the second fuel injection operating state, the electronic control unit 70 determines that this process is unnecessary and terminates this process.

[0029] When it is determined in step S100 that the operation state is being switched from the first fuel injection operation state to the second fuel injection operation state, a threshold temperature Tref is set based on the concentration Cet of ethanol in the fuel (step S110), and it is determined whether the temperature Tcyl of the wall surface (cylinder wall surface) of the combustion chamber 29 of the engine 12 and the temperature Ttop of the top surface of the piston 32 of the engine 12 are below the threshold temperature Tref (step S120). The threshold temperature Tref is a threshold for determining whether fuel adheres to the wall surface (cylinder wall surface) of the combustion chamber 29 or the top surface of the piston 32, and can be the temperature at which the fuel boils or a temperature slightly lower than that temperature. If fuel adheres to the wall surface (cylinder wall surface) of the combustion chamber 29 or the top surface of the piston 32, the fuel (atomized fuel) contributing to explosive combustion will be insufficient, causing the air-fuel ratio to become lean. Therefore, the threshold temperature Tref also serves as a threshold for suppressing the air-fuel ratio from becoming lean. Because the threshold temperature Tref is the boiling temperature of fuel or a temperature slightly lower than that temperature, it is preferable to set the threshold temperature Tref so that it decreases as the ethanol concentration Cet in the fuel increases, as shown in the example of the relationship between the ethanol concentration Cet in the fuel and the threshold temperature Tref in Figure 3. This is based on the fact that the boiling temperature of fuel decreases as the ethanol concentration Cet in the fuel increases. If it is determined in step S120 that the temperature Tcyl of the wall surface (cylinder wall surface) of the combustion chamber 29 of the engine 12 or the temperature Ttop of the top surface of the piston 32 of the engine 12 is equal to or higher than the threshold temperature Tref, it is determined that an increase in the amount of fuel is not necessary, and the process ends.

[0030] If it is determined in step S120 that the temperature Tcyl of the wall surface (cylinder wall surface) of the combustion chamber 29 of the engine 12 or the temperature Ttop of the top surface of the piston 32 of the engine 12 is less than the threshold temperature Tref, a fuel increase value Qadd is calculated for each cylinder from the start of fuel increase until fuel injection is completed for all cylinders of the engine 12 (from the start of fuel increase until the crankshaft 14 rotates 720 degrees) based on the injection pattern, the engine 12 coolant temperature Tw, the ethanol concentration Ccyl in the fuel, and the timing Tf of the first fuel injection from the direct injection valve 26 (steps S130 and S140). This means that the fuel increase is executed from the start of fuel increase until the crankshaft 14 rotates 720 degrees, but the fuel increase value Qadd is calculated and fuel is injected for each cylinder. The fuel increase value Qadd is smaller in the port injection mode than in the direct injection mode. In the combined injection mode, it is preferable to calculate the fuel increase value Qadd so that it tends to decrease as the port injection distribution ratio increases, as shown in FIG. 4, which is an example of the relationship between the fuel injection distribution ratio (port injection distribution ratio) of the port injection valve 25 and the fuel increase value Qadd. This is based on the fact that the larger the port injection distribution ratio, the easier it is to atomize the fuel and the less likely it is that the fuel will adhere to the wall surface (cylinder wall surface) of the combustion chamber 29 and the top surface of the piston 32. Furthermore, it is preferable to calculate the fuel increase value Qadd so that it tends to decrease as the number of fuel injections by the direct injection valve 26 increases, as shown in FIG. 5, which is an example of the relationship between the number of fuel injections by the direct injection valve 26 and the fuel increase value Qadd. This is based on the fact that the more fuel injections by the direct injection valve 26 increase, the easier it is to atomize the fuel and the less likely it is that the fuel will adhere to the wall surface (cylinder wall surface) of the combustion chamber 29 and the top surface of the piston 32. As shown in an example of the relationship between the engine 12 coolant temperature Tw, the ethanol concentration Cet in the fuel, and the fuel increase value Qadd in Fig. 6, it is preferable to calculate the fuel increase value Qadd so that it tends to increase as the engine 12 coolant temperature Tw decreases and as the ethanol concentration Cet increases. This is based on the fact that the lower the engine 12 coolant temperature Tw or the higher the ethanol concentration Cet, the easier the fuel is to atomize and the less likely the fuel is to adhere to the wall surface (cylinder wall surface) of the combustion chamber 29 and the top surface of the piston 32.The fuel increase value Qadd may be determined, for example, by determining in advance the relationship between the timing Tf of the first fuel injection from the in-cylinder injection valve 26 and the increase coefficient k by which the fuel increase value Qadd is multiplied by through experiments, machine learning, or the like, and storing the result as a map for setting the increase coefficient; when the timing Tf of the first fuel injection from the in-cylinder injection valve 26 is given, the corresponding increase coefficient k is derived from the map, and the fuel increase value calculated based on the injection pattern, the cooling water temperature Tw of the engine 12, the ethanol concentration Ccyl in the fuel, etc., is multiplied by the increase coefficient k.

[0031] When the crankshaft 14 has rotated 720 degrees since the start of fuel increase, a positive determination is made in step S140, and the fuel increase value Qadd starts to decay (step S150). The fuel increase value Qadd may be decayed by subtracting a fixed amount from the fuel increase value Qadd calculated for each cylinder each time fuel is injected into that cylinder, or by multiplying the fuel increase value Qadd calculated for each cylinder by a decay coefficient.

[0032] When the fuel increase value Qadd becomes less than the threshold value Qref (step S160), it is determined that the fuel increase is complete, and this process ends. A value close to 0 can be used as the threshold value Qref.

[0033] In the engine device of the embodiment described above, when switching from a first fuel injection operating state in which the engine 12 is operated by injecting fuel from the direct injection valve 26 in the latter half of the compression stroke to a second fuel injection operating state in which the engine 12 is operated by injecting fuel from the direct injection valve 26 before the compression stroke, the fuel injection amount is increased. This makes it possible to prevent the air-fuel ratio from becoming lean even if fuel adheres to the wall surface (cylinder wall surface) of the combustion chamber 29 or the top surface of the piston 32.

[0034] In the engine device of the embodiment, the fuel increase value Qadd is calculated for each cylinder based on the injection pattern, the engine 12 cooling water temperature Tw, the ethanol concentration Ccyl in the fuel, and the initial fuel injection timing Tf from the in-cylinder injection valve 26, so the fuel increase value Qadd can be determined more accurately.

[0035] In the engine device of the embodiment, the fuel increase value Qadd starts to be attenuated when the crankshaft 14 has rotated 720 degrees since the fuel increase was started, so the fuel increase value Qadd can be attenuated more appropriately.

[0036] Although the engine device 10 of the embodiment is provided with the port injection valve 25 and the in-cylinder injection valve 26, the port injection valve 25 may not be provided.

[0037] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained below. In the embodiment, the engine 12 corresponds to the "engine" and the electronic control unit 70 corresponds to the "controller."

[0038] The correspondence between the main elements of the embodiments 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 embodiments 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 embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0039] The above describes the form (embodiment) for carrying out the present invention, but the present invention is not limited to such an embodiment, 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]

[0040] The present invention can be used in the engine device manufacturing industry and the like. [Explanation of symbols]

[0041] 10 engine device, 12 engine, 14 crankshaft, 14a crank position sensor, 15 crank position sensor, 22 air cleaner, 23 intake pipe, 23a air flow meter, 23t temperature sensor, 24 throttle valve, 24a throttle position sensor, 25 port injection valve, 26 in-cylinder injection valve, 28 intake valve, 29 combustion chamber, 30 spark plug, 31 exhaust valve, 32 piston, 33 exhaust pipe, 34 purification device, 34a catalyst, 35 air-fuel ratio sensor, 36 oxygen sensor, 40 water temperature sensor, 44 cam position sensor, 50 fuel supply device, 51 fuel tank, 51t fuel temperature sensor, 52 feed pump, 52a rotation speed sensor, 53 low-pressure supply pipe, 53p fuel pressure sensor, 54 check valve, 55 relief flow path, 56 relief valve, 57 High-pressure pump, 57a solenoid valve, 57b check valve, 57c plunger, 58 high-pressure supply pipe, 58p fuel pressure sensor, 70 electronic control unit, 71 CPU, 72 ROM, 73 RAM, 74 flash memory.

Claims

1. An engine device comprising an engine having a port injection valve and an in-cylinder injection valve, and a control device for controlling the engine, the control device executes a predetermined fuel increase control to increase the fuel injection amount when switching from a first fuel injection operating state in which the engine is operated by injecting fuel from the direct injection valve in the latter half of the compression stroke to a second fuel injection operating state in which the engine is operated by injecting fuel from the direct injection valve before the compression stroke, the control device adjusts the fuel increase value in the predetermined fuel increase control so that the fuel increase value decreases as the port injection distribution ratio increases in the fuel injection modes of the port injection valve and the direct injection valve. An engine device characterized by:

2. 2. The engine device according to claim 1, the control device executes the predetermined fuel increase control when a cylinder wall surface temperature or a piston top surface temperature of the engine is lower than a threshold temperature. Engine equipment.

3. 3. The engine device according to claim 2, the control device uses a temperature based on an ethanol concentration in the fuel as the threshold temperature; Engine equipment.

4. An engine device according to claim 1, the control device adjusts the fuel increase value so that the lower the engine coolant temperature is and the higher the ethanol concentration is, the larger the fuel increase value tends to be. Engine equipment.

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