JP2009062940A - Fuel injection control device of internal combustion engine and internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain generation of PM and smoke in warming-up, in an internal combustion engine for directly injecting fuel into a combustion space in a cylinder, while enabling use of alcohol fuel. <P>SOLUTION: This internal combustion engine 1 can use the alcohol fuel, and has a fuel injection valve 21 for directly injecting the fuel into the combustion space 30B in the cylinder. Before completing the warming-up of the internal combustion engine 1, the timing for injecting the fuel from the fuel injection valve 21 in an intake stroke, is delayed more than the timing for injecting the fuel in the intake stroke after completing the warming-up of the internal combustion engine 1. Control for delaying the timing for injecting the fuel from the fuel injection valve 21, is changed based on the alcohol concentration of the fuel of the internal combustion engine 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention directly injects fuel into a combustion space in a cylinder, and can use not only gasoline but also oxygen-containing fuel such as alcohol or a mixture of gasoline and oxygen-containing fuel such as alcohol. Related to institutions.

  In recent years, from the viewpoint of responding to the diversification of energy with a view to suppressing consumption of fossil fuels, mainly petroleum, in addition to gasoline, fuels containing oxygen-containing fuels such as alcohol and gasoline, An internal combustion engine that can use only oxygen fuel is being put into practical use. Patent Document 1 discloses a technology that includes a port injection valve that injects fuel into an intake pipe and ensures the time required for vaporization by increasing the fuel injection timing as the alcohol concentration of the fuel increases.

JP-A-3-54332, page 4, FIG.

  By the way, the technique disclosed in Patent Document 1 is for an internal combustion engine including a port injection valve, and is not considered for a direct injection type internal combustion engine that directly injects fuel into a combustion space in a cylinder. The technique disclosed in Patent Document 1 does not consider whether the internal combustion engine is warming up or after warming up.

  When the temperature of the internal combustion engine is very low, particulate matter and smoke called PM (Particulate Matter) are likely to be generated. Therefore, it is preferable to retard the fuel injection timing. However, since the technique disclosed in Patent Document 1 increases the fuel injection timing as the alcohol concentration of the fuel increases, there is a possibility that PM and smoke may increase. On the other hand, in a direct injection type internal combustion engine, if the fuel injection timing in the intake stroke is retarded, there is a problem that fuel adheres to the inner wall of the cylinder and mixes into the oil in the oil pan, thereby diluting the oil.

  The present invention has been made in view of the above, and in an internal combustion engine that can use at least oxygen-containing fuel such as alcohol and directly injects fuel into a combustion space in a cylinder, PM and smoke during warm-up It is an object of the present invention to achieve at least one of suppressing the generation of oil and suppressing the dilution of oil due to fuel mixing into the oil.

  To achieve the above object, a fuel injection control device for an internal combustion engine according to the present invention is a fuel for an internal combustion engine that can use at least alcohol fuel and includes a fuel injection valve that directly injects fuel into a combustion space in a cylinder. The fuel injection timing of the intake stroke before the completion of warming up of the internal combustion engine is retarded from the fuel injection timing of the intake stroke after the completion of warming up of the internal combustion engine. .

  As a desirable aspect of the present invention, in the fuel injection control device for an internal combustion engine, the control for delaying the fuel injection timing of the intake stroke before the completion of warm-up from the fuel injection timing of the intake stroke after the completion of warm-up is terminated. It is preferable to change the warm-up retarded injection end timing based on the alcohol concentration of the fuel.

  According to a preferred aspect of the present invention, in the fuel injection control device for an internal combustion engine, when the alcohol concentration of the fuel is equal to or higher than a predetermined threshold, the warm-up delay is higher than when the alcohol concentration of the fuel is smaller than the threshold. It is preferable to make the angle injection end time earlier.

  As a desirable mode of the present invention, in the fuel injection control device of the internal combustion engine, it is preferable to change a region in which the internal combustion engine is operated at an air / fuel ratio smaller than a stoichiometric air / fuel ratio based on the alcohol concentration of the fuel.

  In order to achieve the above object, an internal combustion engine according to the present invention is an internal combustion engine that can use at least alcohol fuel and directly injects fuel into a combustion space in a cylinder in which a piston reciprocates. When injecting the fuel in a stroke, a fuel injection valve for injecting the fuel into the combustion space by delaying the timing of injecting the fuel before completion of warm-up than after completion of warm-up is provided. It is characterized by.

  As a preferred aspect of the present invention, in the fuel injection control device for an internal combustion engine, the fuel injection valve finishes the control in which the timing of injecting fuel before the completion of warm-up is delayed than after the completion of warm-up. It is preferable to change the warm-up retarded injection end timing based on the alcohol concentration of the fuel.

  As a desirable aspect of the present invention, in the fuel injection control device for an internal combustion engine, the fuel injection valve is configured such that the alcohol concentration of the fuel is lower than the threshold value when the alcohol concentration of the fuel is equal to or higher than a predetermined threshold value. It is preferable to make the warm-up delay angle injection end timing earlier than when it is smaller.

  As a preferred aspect of the present invention, in the fuel injection control device for the internal combustion engine, the fuel injection valve has a region in which the internal combustion engine is operated at an air / fuel ratio smaller than a stoichiometric air / fuel ratio based on an alcohol concentration of the fuel. It is preferable to change.

  In an internal combustion engine that can use at least an oxygen-containing fuel such as alcohol and directly injects fuel into a combustion space in a cylinder, the present invention suppresses the generation of PM and smoke during warm-up, and the fuel is converted into oil. At least one of suppressing dilution of oil due to mixing can be achieved.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the best mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. The present invention is suitable for an internal combustion engine that can use at least alcohol fuel. Here, the alcohol fuel means an oxygen-containing fuel such as alcohol or a fuel obtained by mixing gasoline and an oxygen-containing fuel such as alcohol.

(Embodiment 1)
Embodiment 1 is an internal combustion engine that directly injects fuel into a combustion space in a cylinder and can use not only gasoline but also oxygen-containing fuel such as alcohol, or a mixture of gasoline and oxygen-containing fuel such as alcohol. In fuel injection control of an engine, that is, an internal combustion engine that can use at least alcohol fuel, the fuel injection timing and the fuel injection amount are changed based on the alcohol concentration of the fuel. Here, the fuel injection control is control for changing the fuel injection timing, the fuel injection amount, and the like.

  FIG. 1 is a schematic configuration diagram showing the configuration of the internal combustion engine according to the first embodiment. The internal combustion engine 1 includes a fuel supply device 2, an internal combustion engine body 3 having a cylinder 30, an intake path 5 connected to the internal combustion engine body 3, and an exhaust path 6 connected to the internal combustion engine body 3. Prepare. The operation of the internal combustion engine 1 is controlled by an engine ECU (Electronic Control Unit) 7 which is a control device.

  In the internal combustion engine 1, the fuel F stored in the fuel tank 22 is supplied to the cylinder 30 by the fuel supply device 2. The internal combustion engine 1 can use not only gasoline, but also oxygen-containing fuel such as alcohol, or fuel obtained by mixing gasoline and oxygen-containing fuel such as alcohol. In the present embodiment, the fuel F is, for example, a mixed fuel of gasoline and alcohol (for example, ethanol). The fuel supply device 2 includes a fuel injection valve 21, a fuel tank 22, a low pressure fuel pump 23, a high pressure fuel pump 24, fuel supply pipes 26 to 28, and a fuel distribution pipe (so-called fuel delivery pipe) 25. It is out.

  The fuel injection valve 21 constituting the fuel supply device 2 is attached to a cylinder head 32 of the internal combustion engine main body 3, and a fuel injection port is opened in a combustion space (cylinder combustion space) 30B in a cylinder described later. The fuel F is directly injected into the in-cylinder combustion space 30B of the internal combustion engine 1 from the fuel injection port of the fuel injection valve 21 opened in the in-cylinder combustion space 30B, and a fuel spray Fm is formed in the in-cylinder combustion space 30B. Is done. Thus, the internal combustion engine 1 according to this embodiment is supplied with the fuel F by a so-called direct injection system. The fuel injection control relating to the fuel injection amount of the fuel injection valve 21 (the fuel supply amount of the fuel F supplied to the internal combustion engine 1), the injection timing, etc. is executed by the engine ECU 7 which is a control device. In the present embodiment, a port injection valve that injects fuel into the intake port 37 may be further provided.

  The fuel F in the fuel tank 22 is sent to a high pressure fuel pump 24 which is a fuel pressure sending means by a low pressure fuel pump 23, and is sent from the high pressure fuel pump 24 to a fuel distribution pipe 25. The pressure of the fuel F in the fuel distribution pipe 25 is set to, for example, several tens of MPa. An alcohol concentration sensor 29 is attached to the fuel distribution pipe 25. The alcohol concentration sensor 29 detects the alcohol concentration of the fuel F filled in the fuel distribution pipe 25. The alcohol concentration of the fuel F detected by the alcohol concentration sensor 29 is taken into the engine ECU 7 and used for fuel injection timing control according to the present embodiment. By attaching the alcohol concentration sensor 29 to the fuel distribution pipe 25, it is possible to detect the alcohol concentration of the fuel immediately before being injected from the fuel injection valve 21 into the in-cylinder combustion space 30B, thereby improving the accuracy of fuel injection timing control.

  An internal combustion engine body 3 of the internal combustion engine 1 includes a cylinder block 31, a cylinder head 32 fastened and integrated with the cylinder block 31, a crankcase 30 </ b> C fastened and integrated with the cylinder block 31, and a cylinder 30. A piston 33 and a connecting rod 34 provided, a crankshaft 35, a spark plug 36 provided in the cylinder 30, and a valve device 4 are provided.

  A cylinder 30 included in the internal combustion engine body 3 is formed with an in-cylinder combustion space 30 </ b> B surrounded by a piston 33, a cylinder block 31, and a cylinder head 32. In the cylinder combustion space 30 </ b> B of the cylinder 30, an intake port 37 connected to the intake path 5 and an exhaust port 38 connected to the exhaust path 6 are formed. The intake port 37 and the exhaust port 38 are formed in the cylinder head 32.

  The piston 33 is rotatably attached to the connecting rod 34, and the connecting rod 34 is rotatably attached to the crankshaft 35. Thus, the piston 33 is connected to the crankshaft 35 via the connecting rod 34. In the internal combustion engine body 3, the air-fuel mixture of air A and fuel F is burned in the in-cylinder combustion space 30 </ b> B of the cylinder 30 to cause the piston 33 to reciprocate in the cylinder block 31. To convert to rotary motion and output.

  The internal combustion engine body 3 includes a crank angle sensor 39 that functions as means for detecting the rotation speed (engine rotation speed) of the crankshaft 35 provided in the internal combustion engine body 3 and means for detecting the angle of the crankshaft 35. The crank angle sensor 39 detects a crank angle (CA) that is the angle of the crankshaft 35 and outputs it to the engine ECU 7. The engine ECU 7 calculates the rotational speed of the internal combustion engine 1 (the rotational speed per unit time and also referred to as the engine rotational speed) from the crank angle detected by the crank angle sensor 39, or the stroke of the cylinder 30 (for example, , Whether it is an intake stroke, a compression stroke, an expansion stroke, or an exhaust stroke).

  A spark plug 36 is attached to the cylinder head 32 of the internal combustion engine body 3. The electrode 36S of the spark plug 36 protrudes into the in-cylinder combustion space 30B of the cylinder 30. Further, a direct ignition 36DI is attached to the spark plug 36. The direct ignition 36DI discharges the ignition plug 36 by an ignition signal from the engine ECU 7 functioning as an ignition timing adjusting means, and ignites the air-fuel mixture in the in-cylinder combustion space 30B of the cylinder 30. As a result, the air-fuel mixture burns to become high-temperature and high-pressure combustion gas, and drives the piston 33. Here, the ignition operation relating to the discharge timing of the spark plug 36 is controlled by the engine ECU 7 which is a control device for controlling the operation of the internal combustion engine 1.

  The internal combustion engine body 3 includes a valve device 4 for opening and closing an intake valve 41 and an exhaust valve 42. The valve device 4 includes an intake valve 41 and an exhaust valve 42 provided in the cylinder 30, an intake camshaft 43, an exhaust camshaft 44, an intake valve timing change mechanism 45, and an exhaust valve timing change mechanism 47. Is done.

  The intake valve 41 constituting the valve device 4 is disposed in an opening portion between the intake port 37 and the in-cylinder combustion space 30B, and opens and closes when the intake camshaft 43 rotates. The exhaust valve 42 constituting the valve device 4 is disposed at an opening portion between the exhaust port 38 and the in-cylinder combustion space 30B, and opens and closes when the exhaust camshaft 44 rotates.

  The intake camshaft 43 and the exhaust camshaft 44 of the valve device 4 rotate in conjunction with the rotation of the crankshaft 35 via a timing chain or a timing belt. The intake valve timing changing mechanism 45 of the valve device 4 is attached to the intake camshaft 43, and the exhaust valve timing changing mechanism 47 is attached to the exhaust camshaft 44.

  The intake valve timing changing mechanism 45 and the exhaust valve timing changing mechanism 47 are variable valve mechanisms. The intake valve timing changing mechanism 45 continuously changes the phase of the intake camshaft 43, and the exhaust valve timing changing mechanism 47 exhausts. The phase of the camshaft 44 is continuously changed. Accordingly, the intake valve timing changing mechanism 45 and the exhaust valve timing changing mechanism 47 can continuously change the opening / closing timing of the intake valve 41 and the opening / closing timing of the exhaust valve 42, so that the operation state of the internal combustion engine 1 is changed. Accordingly, the opening / closing timing of the intake valve 41 and the opening / closing timing of the exhaust valve 42 can be controlled to the optimum timing.

  The valve device 4 detects the rotational position of the intake camshaft 43 and outputs it to the engine ECU 7. The exhaust camshaft sensor 46 detects the rotational position of the exhaust camshaft 44 and outputs it to the engine ECU7. A position sensor 48 is provided. Outputs of the intake cam position sensor 46 and the exhaust cam position sensor 48 are taken into the engine ECU 7 and used for control of the ignition timing of the spark plug 36 and control of the intake valve timing change mechanism 45 and the exhaust valve timing change mechanism 47.

  An intake cam 43C is attached to the intake cam shaft 43, and an exhaust cam 44C is attached to the exhaust cam shaft 44. As intake camshaft 43 and exhaust camshaft 44 rotate, intake cam 43C and exhaust cam 44C rotate. As a result, the intake cam 43C opens and closes the intake valve 41, and the exhaust cam 44C opens and closes the exhaust valve 42.

  The intake passage 5 of the internal combustion engine body 3 sucks air A in the atmosphere and introduces the sucked air A into an in-cylinder combustion space 30 </ b> B formed in the cylinder 30 of the internal combustion engine body 3. The intake passage 5 includes an air cleaner 51, an air flow meter 52, a throttle valve 53, and an intake passage 54 that communicates from the air cleaner 51 to the intake port 37 of the cylinder 30. The intake path 5 introduces the air A from which dust or dust has been removed by the air cleaner 51 into the in-cylinder combustion space 30 </ b> B of each cylinder 30 via the intake passage 54 and the intake port 37. An air flow meter 52 provided in the intake path 5 is intake air amount detection means, detects the amount of intake air drawn from the intake path 5 and introduced into the cylinder 30, and outputs it to the engine ECU 7.

  The intake path 5 is provided with a throttle valve 53 that functions as intake air amount adjusting means for adjusting and controlling the intake air amount supplied to the in-cylinder combustion space 30B. The throttle valve 53 adjusts the amount of intake air introduced into the in-cylinder combustion space 30B of the cylinder 30. The throttle valve 53 is opened and closed by an actuator 53a such as a stepping motor. The opening degree of the throttle valve 53 that functions as the intake air amount adjusting means, that is, the opening degree of the throttle valve is controlled by the engine ECU 7 adjusting the opening degree of the throttle valve 53 by the actuator 53a.

  In the exhaust path 6 connected to the internal combustion engine main body 3, the combustion gas after combustion in the in-cylinder combustion space 30 </ b> B of the cylinder 30 and driving the piston 33 is discharged as exhaust gas. The exhaust path 6 includes an exhaust gas passage 62 and an exhaust gas purification catalyst 61 provided in the exhaust gas passage 62. The exhaust gas purification catalyst 61 provided in the exhaust path 6 purifies nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC) contained in the exhaust gas Ex sent from the exhaust gas passage 62. The exhaust gas after being purified by the exhaust gas purification catalyst 61 is exhausted into the atmosphere through a silencer.

An A / F sensor 63 and an O ₂ sensor 64 are provided in the exhaust gas passage 62. The A / F sensor 63 as air-fuel ratio detection means is a sensor having an output characteristic that is substantially proportional to the air-fuel ratio of the exhaust gas Ex. The A / F sensor 63 is arranged on the upstream side of the exhaust gas purification catalyst 61 in the exhaust gas passage 62, that is, between the exhaust port 38 of the internal combustion engine 1 and the exhaust gas purification catalyst 61. The A / F sensor 63 detects the exhaust gas air-fuel ratio of the exhaust gas Ex before being sucked into the exhaust gas purification catalyst 61 out of the exhaust gas Ex exhausted from the in-cylinder combustion space 30B to the exhaust path 6, and outputs it to the engine ECU 7. . The A / F sensor 63 may be an O ₂ sensor.

Further, the engine ECU 7 calculates the air-fuel ratio of the air-fuel mixture composed of the sucked air A and the fuel F, that is, the air-fuel ratio of the internal combustion engine 1 based on the exhaust gas air-fuel ratio detected by the A / F sensor 63. The O ₂ sensor 64 provided in the exhaust path 6 is a sensor that detects the oxygen concentration in the exhaust gas Ex, and functions as an oxygen concentration detection unit. The O ₂ sensor 64 is disposed on the downstream side of the exhaust gas purification catalyst 61 in the exhaust gas passage 62, that is, on the outlet side of the exhaust gas purification catalyst 61. The O ₂ sensor 64 detects the oxygen concentration of the exhaust gas Ex after passing through the exhaust gas purification catalyst 61 out of the exhaust gas Ex discharged from the in-cylinder combustion space 30B to the exhaust path 6, and outputs the detected oxygen concentration to the engine ECU 7.

As described above, various input signals are input to the engine ECU 7 from sensors attached to various parts of the vehicle in order to control and operate the internal combustion engine 1. Input signals input to the engine ECU 7 include, for example, a crank angle detected by a crank angle sensor 39 attached to the crankshaft 35, an intake air amount detected by an air flow meter 52, and an accelerator opening sensor 8. Cooling for detecting the opening of the accelerator 8P (accelerator opening), the exhaust gas air-fuel ratio detected by the A / F sensor 63, the oxygen concentration detected by the O ₂ sensor 64, and the temperature of the cooling water for cooling the internal combustion engine 1 The temperature of the cooling water output from the water temperature sensor 65 (cooling water temperature), the alcohol concentration of the fuel F detected by the alcohol concentration sensor 29, and the like.

  The engine ECU 7 controls the operation of the internal combustion engine 1 based on various maps such as the above-described input signal and a map describing the fuel injection amount stored in the storage unit 73 and a map describing the ignition timing. A control signal is output to the fuel injection valve 21, the direct ignition 36DI, and the like to be controlled. Examples of control signals that the engine ECU 7 outputs to execute operation control of the internal combustion engine 1 include a fuel injection signal that controls fuel injection of the fuel injection valve 21, an ignition signal that controls ignition of the spark plug 36, and a throttle valve. There is a valve opening signal for controlling the valve opening 53.

  The engine ECU 7 includes an input / output unit (I / O) 71 that inputs and outputs the above-described input signal and output signal, a processing unit 72, and a storage unit 73 that stores various maps such as a fuel injection amount map. . The processing unit 72 includes, for example, a memory and a CPU (Central Processing Unit). The processing unit 72 includes a fuel injection condition setting unit 74, a fuel injection control unit 75, and an intake / exhaust valve control unit 76. These execute the fuel injection control according to the present embodiment.

  Thus, since the engine ECU 7 is configured to include means for executing the fuel injection control according to the present embodiment, the engine ECU 7 is configured to operate the fuel injection control device for an internal combustion engine (hereinafter referred to as fuel injection control) according to the present embodiment. Function as a control device). The storage unit 73 is a non-volatile memory such as a flash memory, a memory that can be read only such as a ROM (Read Only Memory), or a memory that can be read and written such as a RAM (Random Access Memory). It can be configured by a combination of Next, fuel injection control according to this embodiment will be described.

  In the fuel injection control according to the present embodiment, as in the internal combustion engine 1 shown in FIG. 1, fuel is supplied by a so-called direct injection system, and not only gasoline but also oxygen-containing fuel such as alcohol, or gasoline and alcohol. The present invention is effectively applied to an internal combustion engine that can use a fuel mixed with such an oxygen-containing fuel. The fuel injection control according to the present embodiment is a first fuel injection control that is executed when the internal combustion engine 1 is cold-started, and a second fuel that is executed when the internal combustion engine 1 is operated under high operating conditions. There is injection control.

(First fuel injection control)
FIG. 2 is a schematic diagram for explaining the fuel injection timing. 2 indicates the direction of rotation of the crankshaft 35 provided in the internal combustion engine 1 shown in FIG. FIG. 3 is an explanatory diagram showing the relationship between the fuel injection timing and the coolant temperature. The first fuel injection control (hereinafter referred to as first fuel injection control) is executed after the cold start of the internal combustion engine 1 shown in FIG. 1 until the warm-up is completed. The direct injection internal combustion engine 1 changes the fuel injection timing according to the combustion mode of the air-fuel mixture. For example, when the internal combustion engine 1 is operated by homogeneous combustion, the fuel is injected in the intake stroke in order to improve air filling efficiency and to sufficiently mix the fuel and air. This is called intake stroke injection. In the intake stroke injection, fuel is injected between the intake top dead center TDC_I and the intake bottom dead center BDC_I shown in FIG. Further, when the internal combustion engine 1 is operated by stratified combustion, fuel is injected in the compression stroke in order to form a stratified mixture near the electrode 36S of the spark plug 36. This is called compression stroke injection.

  In the first fuel injection control according to the present embodiment, after the warm-up of the internal combustion engine 1 shown in FIG. 1 is completed, the air filling efficiency is improved and the fuel and air are sufficiently mixed. Fuel is injected at a fuel injection timing θ1 close to TDC_I. On the other hand, during the period from the cold start of the internal combustion engine 1 shown in FIG. 1 to the completion of warm-up, that is, during warm-up, the fuel and air are sufficiently mixed, so that fuel is injected by intake stroke injection. In this case, if fuel is injected in the vicinity of the intake top dead center TDC_I shown in FIG. 2, smoke and PM are likely to be generated. This phenomenon becomes more prominent as the gasoline concentration of the fuel F increases. In order to suppress this, the fuel is injected at the retarded fuel injection timing (θ2) as compared to the fuel injection timing (θ1) after completion of warm-up.

  As described above, in the first fuel injection control according to the present embodiment, the fuel injection timing in the intake stroke before the warm-up of the internal combustion engine 1 is completed is higher than the fuel injection timing in the intake stroke after the warm-up of the internal combustion engine 1 is completed. Retard. Thereby, generation | occurrence | production of PM and smoke during warming-up of the internal combustion engine 1 can be suppressed.

  Here, there is a phenomenon called oil dilution in which oil that lubricates the sliding portion of the internal combustion engine 1 is diluted with fuel. This is because, after the fuel F injected from the fuel injection valve 21 shown in FIG. 1 collides with the cylinder inner wall 30iw, it passes between the piston 33 and the cylinder inner wall 30iw and is mixed into the oil in the oil pan to dilute the oil. It is a phenomenon. In the direct injection method in which the fuel F is directly injected into the in-cylinder combustion space 30B, the fuel spray Fm easily reaches the cylinder inner wall 30iw, so that oil dilution becomes particularly significant. Oil dilution is likely to occur under conditions where the temperature of the cylinder inner wall 30iw is low and the fuel F adhering to the cylinder inner wall 30iw does not easily evaporate.

  Usually, an internal combustion engine includes a blow-by gas reduction device that returns blow-by gas to an intake passage. The fuel F mixed in and diluted with oil evaporates as the internal combustion engine 1 is warmed up and the temperature of the oil rises. The evaporated fuel F returns to the intake passage 54 of the internal combustion engine 1 shown in FIG. 1 through the blow-by gas reduction device, is introduced into the in-cylinder combustion space 30B through the intake port 37, and burns. When the fuel F mixed in the oil evaporates from the oil and returns to the intake passage 54, the air-fuel ratio of the internal combustion engine 1 is disturbed. Therefore, the air-fuel ratio is adjusted by adjusting the fuel injection amount from the fuel injection valve 21.

  When the fuel injection timing is retarded from the intake top dead center TDC_I, the piston 33 shown in FIG. 1 approaches the bottom dead center, and the area where the cylinder inner wall 30iw is exposed into the cylinder combustion space 30B increases. As a result, when the fuel injection timing is retarded from the intake top dead center TDC_I, the fuel F tends to adhere to the cylinder inner wall 30iw, and the amount of the fuel F mixed in the oil tends to increase.

  When the fuel injection timing is retarded after completion of warm-up and the amount of fuel F mixed into the oil increases, the fuel of the internal combustion engine 1 is not a problem when gasoline is used as the fuel of the internal combustion engine 1, even though it does not matter. May contain problems if alcohol is included. This is because alcohol is less likely to evaporate than gasoline, and the calorific value of alcohol is smaller than that of gasoline, so if you want to get the same calorific value, you need to inject more than gasoline. caused by. Problems caused by an increase in the amount of fuel F that dilutes oil include, for example, that alcohol is less likely to evaporate than gasoline and that more fuel must be injected than gasoline, resulting in more fuel in the oil. There is a problem of mixing. Further, since alcohol is less likely to evaporate than gasoline, alcohol mixed in the oil abruptly evaporates after completion of warm-up of the internal combustion engine 1 and returns to the intake passage 54 of the internal combustion engine 1, making it difficult to control the air-fuel ratio. There is also a problem.

  On the other hand, when alcohol is injected in the vicinity of the intake top dead center TDC_I shown in FIG. 2 during warm-up, it is less likely to generate particulate matter called smoke or PM (Particulate Matter) than gasoline. It has properties. Therefore, in the present embodiment, the fuel injection timing in the intake stroke before the completion of warming up of the internal combustion engine 1 shown in FIG. 1 is delayed from the fuel injection timing in the intake stroke after the completion of warming up of the internal combustion engine 1. Is changed based on the alcohol concentration of the fuel F of the internal combustion engine 1. More specifically, when the alcohol concentration of the fuel F is equal to or higher than a predetermined threshold, the retarded injection end timing is set earlier than when the alcohol concentration of the fuel F is smaller than the threshold.

  A solid line A in FIG. 3 indicates the fuel injection timing when the alcohol concentration of the fuel F of the internal combustion engine 1 is equal to or higher than a predetermined threshold. 3 indicates the fuel injection timing when the alcohol concentration of the fuel F of the internal combustion engine 1 is smaller than a predetermined threshold. As for the fuel injection timing θ in FIG. 3, the fuel is injected on the retarded side of θ2 relative to θ1, that is, the intake bottom dead center BDC_I side rather than the intake top dead center TDC_I side shown in FIG.

  In the present embodiment, the warm-up retarded injection end timing is determined based on the coolant temperature Tw of the internal combustion engine 1. For example, when the alcohol concentration of the fuel F of the internal combustion engine 1 is smaller than a predetermined threshold value, it is determined that the internal combustion engine 1 has been warmed up when the coolant temperature Tw = Tw2, and the fuel injection timing is The fuel injection timing θ2 before the completion is switched to the fuel injection timing θ1 after the completion of the warm-up. That is, the control for delaying the fuel injection timing of the intake stroke before the completion of warm-up from the fuel injection timing of the intake stroke after the completion of warm-up ends when the coolant temperature Tw = Tw2. As a result, smoke and PM are suppressed until warm-up is completed, and after warm-up, air charging efficiency is improved and fuel and air are mixed thoroughly to achieve proper combustion. The internal combustion engine 1 is operated in the state.

  Further, when the alcohol concentration of the fuel F of the internal combustion engine 1 is equal to or higher than a predetermined threshold value, it is determined that the warm-up of the internal combustion engine 1 is completed when the coolant temperature Tw = Tw1, and the fuel injection timing is determined to be complete. The previous fuel injection timing θ2 is switched to the fuel injection timing θ1 after completion of warm-up. That is, the control for delaying the fuel injection timing of the intake stroke before the completion of warm-up from the fuel injection timing of the intake stroke after the completion of warm-up ends when the coolant temperature Tw = Tw1.

  As described above, the cooling water temperature for determining the warm-up retarded injection end timing when the alcohol concentration of the fuel F of the internal combustion engine 1 is equal to or higher than a predetermined threshold is Tw1, and the alcohol of the fuel F of the internal combustion engine 1 is alcohol. The coolant temperature for determining the warm-up retarded injection end timing when the concentration is smaller than the predetermined threshold is Tw2. Here, since Tw1 <Tw2, when the alcohol concentration of the fuel F of the internal combustion engine 1 is equal to or greater than a predetermined threshold, the alcohol concentration of the fuel F of the internal combustion engine 1 is higher than the predetermined threshold at the warm-up retarded injection end timing. Is earlier than the warm-up retarded injection end timing.

  As described above, when the warm-up retarded injection end timing is changed based on the alcohol concentration of the fuel F of the internal combustion engine 1, when the alcohol concentration of the fuel F is high, the warm-up retarded injection end is completed. The time ends earlier. In this case, the generation of smoke and PM can be suppressed by utilizing the property of alcohol that smoke and PM are less likely to be generated than gasoline. Moreover, since the fuel injection timing shifts to the intake top dead center side, the amount of fuel F mixed into the oil can be suppressed. Next, the procedure of the first fuel injection control according to this embodiment will be described.

  FIG. 4 is a flowchart showing a procedure of first fuel injection control according to the first embodiment. FIG. 5 is an explanatory diagram of a method for determining the coolant temperature for switching the warm-up retarded injection end timing of the first fuel injection control according to the first embodiment. In executing the first fuel injection control according to the present embodiment, in step S101, the fuel injection condition setting unit 74 of the engine ECU 7 acquires the alcohol concentration Ce of the fuel in the fuel distribution pipe 25 detected by the alcohol concentration sensor 29. To do.

  Next, in step S102, the fuel injection condition setting unit 74 determines whether or not the coolant temperature Tw1 is being used as the fuel injection control switching temperature Tc. Here, the cooling water temperature Tw1 is a cooling water temperature used for determination to switch from the fuel injection timing before completion of warm-up to the fuel injection timing after completion of warm-up when the alcohol concentration of the fuel F is equal to or higher than a predetermined threshold. is there. That is, when the alcohol concentration of the fuel F is equal to or higher than a predetermined threshold, the fuel injection timing is changed from the fuel injection timing before the completion of warming up to the fuel injection timing after the completion of warming up when the cooling water temperature Tw1 or higher. Switch to.

  When it is determined Yes in step S102, that is, when the fuel injection condition setting unit 74 determines that Tw1 is used as the fuel injection control switching temperature Tc, the process proceeds to step S103. In step S103, the fuel injection condition setting unit 74 of the engine ECU 7 determines whether or not the alcohol concentration Ce acquired in step S101 is equal to or higher than a first threshold value Ce1 that is a predetermined threshold value.

  When it is determined Yes in step S103, that is, when the fuel injection condition setting unit 74 determines that Ce ≧ Ce1, it can be determined that the concentration of alcohol that does not easily generate smoke or PM is higher than gasoline. For this reason, smoke and PM can be suppressed even if the control for delaying the fuel injection timing of the intake stroke before the completion of warm-up is earlier than the fuel injection timing of the intake stroke after the completion of warm-up. Moreover, since the fuel injection timing shifts to the intake top dead center side, the amount of fuel F mixed into the oil can be suppressed. In this case, the process proceeds to step S104, and the fuel injection condition setting unit 74 continues to use the coolant temperature Tw1 set as the fuel injection control switching temperature Tc.

  If it is determined No in step S103, that is, if the fuel injection condition setting unit 74 determines that Ce <Ce1, it can be determined that the concentration of alcohol in which smoke and PM are less likely to occur compared to gasoline is low. In this case, if the control for retarding the fuel injection timing of the intake stroke before the completion of warm-up is earlier than the fuel injection timing of the intake stroke after the completion of warm-up, smoke and PM may increase. Therefore, the process proceeds to step S105, and the fuel injection condition setting unit 74 sets the coolant temperature Tw2 as the fuel injection control switching temperature Tc.

  Here, the cooling water temperature Tw2 is a cooling water temperature used for determination to switch from the fuel injection timing before completion of warm-up to the fuel injection timing after completion of warm-up when the alcohol concentration of the fuel F is lower than a predetermined threshold. is there. That is, when the alcohol concentration of the fuel F is lower than the predetermined threshold value, the fuel injection timing is changed from the fuel injection timing before the warm-up completion to the fuel injection timing after the warm-up completion when the cooling water temperature Tw2 or higher. Switch to.

  When the fuel injection control switching temperature Tc is set to Tw1 or Tw2, the process proceeds to step S106, and the fuel injection condition setting unit 74 acquires the coolant temperature Tw. Then, the fuel injection condition setting unit 74 compares the fuel injection control switching temperature Tc with the coolant temperature Tw acquired in step S106. As a result, when the fuel injection condition setting unit 74 determines that Tc ≦ Tw, that is, when it is determined Yes in step S107, it can be determined that the warm-up of the internal combustion engine 1 shown in FIG. In this case, in step S108, the fuel injection condition setting unit 74 sets a post-warm-up injection timing map as a map describing the fuel injection timing, and the fuel injection control unit 75 of the engine ECU 7 sets the post-warm-up injection timing set. The fuel injection timing of the fuel injection valve 21 is controlled using the timing map.

  When the fuel injection condition setting unit 74 determines that Tc> Tw, that is, when it is determined No in step S107, it can be determined that the warm-up of the internal combustion engine 1 shown in FIG. In this case, in step S109, the fuel injection condition setting unit 74 sets the pre-warm-up injection timing map as a map describing the fuel injection timing, and the fuel injection control unit 75 of the engine ECU 7 sets the set pre-warm-up injection. The fuel injection timing of the fuel injection valve 21 is controlled using the timing map.

  Here, if the internal combustion engine 1 has the same operating conditions (the load, the engine speed, the intake air temperature, etc. are the same), the fuel injection timing in the post-warm-up injection timing map is the fuel injection in the pre-warm-up injection timing map. It is described on the advance side of the time, that is, on the intake top dead center side. In addition, the fuel injection timing is set in the post-warm-up injection timing map and the pre-warm-up injection timing map so that the effects of homogenizing the fuel and improving the charging efficiency can be maximized.

  When it is determined No in step S102, that is, when the fuel injection condition setting unit 74 determines that Tw2 is used as the fuel injection control switching temperature Tc, the process proceeds to step S110. In step S110, the fuel injection condition setting unit 74 of the engine ECU 7 determines whether or not the alcohol concentration Ce acquired in step S101 is equal to or higher than a second threshold value Ce2 that is a predetermined threshold value.

  If it is determined No in step S110, that is, if the fuel injection condition setting unit 74 determines that Ce <Ce2, it can be determined that the concentration of alcohol in which smoke and PM are less likely to occur compared to gasoline is low. In this case, if the control for retarding the fuel injection timing of the intake stroke before the completion of warm-up is earlier than the fuel injection timing of the intake stroke after the completion of warm-up, smoke and PM may increase. For this reason, it progresses to step S105 and the fuel injection condition setting part 74 continues use of the cooling water temperature Tw2 set as fuel injection control switching temperature Tc.

  When it is determined Yes in step S110, that is, when the fuel injection condition setting unit 74 determines that Ce ≧ Ce2, it can be determined that the concentration of alcohol that does not easily generate smoke or PM is higher than gasoline. For this reason, smoke and PM can be suppressed even if the control for delaying the fuel injection timing of the intake stroke before the completion of warm-up is earlier than the fuel injection timing of the intake stroke after the completion of warm-up. Moreover, since the fuel injection timing shifts to the intake top dead center side, the amount of fuel F mixed into the oil can be suppressed. In this case, the process proceeds to step S104, and the fuel injection condition setting unit 74 sets the coolant temperature Tw1 as the fuel injection control switching temperature Tc. Since the procedure after the fuel injection control switching temperature Tc is set to Tw1 or Tw2 is as described above, the description thereof is omitted.

  Here, a method for setting the fuel injection control switching temperature Tc based on the alcohol concentration of the fuel will be described with reference to FIG. In the present embodiment, the first threshold value Ce1 is used as the alcohol concentration when the fuel injection control switching temperature Tc is changed from Tw1 to Tw2 (the chain line D in FIG. 5), and the fuel injection control switching temperature Tc is changed from Tw2 to Tw1. The second threshold value Ce2 is used as the alcohol concentration when changing (solid line C in FIG. 5). That is, the first threshold value Ce1 is used as the alcohol concentration when changing the warm-up retarded injection end timing in the high alcohol concentration fuel to the warm-up retarded injection end timing in the low alcohol concentration fuel, and the warm in the low alcohol concentration fuel is used. The second threshold value Ce <b> 2 is used as the alcohol concentration when changing the time delay injection end timing to the warm time delay injection end timing in the high alcohol concentration fuel. Here, Ce1 <Ce2.

  Thus, when changing the warm-up retarded injection end timing in the high alcohol concentration fuel to the warm-up retarded injection end timing in the low alcohol concentration fuel, the warm-up retarded injection end timing in the low alcohol concentration fuel Is changed to the warm-up retarded injection end timing in the high alcohol concentration fuel. Thereby, stable fuel injection control can be realized by suppressing control hunting in switching of the warm-up retarded injection end timing.

  As described above, in the first fuel injection control according to the present embodiment, the fuel injection timing of the intake stroke before the completion of warm-up of the internal combustion engine is delayed from the fuel injection timing of the intake stroke after completion of the warm-up of the internal combustion engine. Thereby, generation | occurrence | production of PM and smoke during warming up of an internal combustion engine can be suppressed. Also, by changing the warm-up retarded injection end timing based on the alcohol concentration of the fuel of the internal combustion engine, smoke and PM are less likely to occur when the alcohol concentration of the fuel is high compared to gasoline. The amount of fuel mixed in the oil can be suppressed while suppressing the generation of smoke and PM by utilizing the property of alcohol.

  Direct-injection internal combustion engines have the advantage of fuel homogenization and improved charging efficiency when fuel is injected at an appropriate timing in the intake stroke. However, if the fuel injection timing is too close to the intake top dead center, The benefits are smaller. In the first fuel injection control according to the present embodiment, the fuel injection timing is not simply advanced to the intake top dead center side as the alcohol concentration increases, but the fuel is homogenized during and after the warm-up. The fuel is injected at a fuel injection timing set so as to maximize the effects of improving fuel efficiency and filling efficiency. As a result, the combustion deterioration of the internal combustion engine can be suppressed and the internal combustion engine can be operated efficiently.

(Second fuel injection control)
The second fuel injection control (hereinafter referred to as second fuel injection control) is characterized in that the region in which the amount of fuel is increased from the fuel injection amount relative to the theoretical air-fuel ratio is changed based on the alcohol concentration of the fuel.

  6 and 7 are explanatory diagrams showing an excess air ratio map used in the second fuel injection control. An internal combustion engine that uses gasoline as a fuel, for example, increases the fuel injection amount relative to the stoichiometric air-fuel ratio under an operating condition where the exhaust gas temperature is high, such as an operating condition under high rotation and high load, with an air-fuel ratio smaller than the stoichiometric air-fuel ratio. Driven. That is, the engine is operated with a fuel injection amount such that the excess air ratio λ (the amount of supplied air / theoretical required amount of air) <1. This reduces the temperature of the exhaust gas and suppresses overheating of the catalyst and parts.

  However, there is a problem that fuel consumption increases because the fuel injection amount is increased. On the other hand, when alcohol is used as the fuel for the internal combustion engine, the temperature of the exhaust gas decreases. For this reason, the region in which the internal combustion engine is operated by increasing the fuel injection amount with respect to the stoichiometric air-fuel ratio can be reduced as compared with the case where only gasoline is used as fuel. That is, the internal combustion engine can be operated without increasing the fuel injection amount up to a high rotation and high load region where the temperature of the exhaust gas becomes higher.

  In the second fuel injection control, the region in which the fuel is increased from the fuel injection amount with respect to the stoichiometric air-fuel ratio is changed based on the alcohol concentration of the fuel. More specifically, the excess air ratio map λ_GS (FIG. 6) used when the alcohol concentration of the fuel is smaller than a predetermined threshold, and the excess air ratio map used when the alcohol concentration of the fuel is greater than or equal to the predetermined threshold. An excess air ratio map λ_AL (FIG. 7) is prepared in which the region in which the amount of fuel is increased is smaller than λ_GS. Then, the excess air ratio map λ_GS and the excess air ratio map λ_AL are switched and used in accordance with the alcohol concentration of the fuel. As a result, in the case of fuel with a high alcohol concentration, by reducing the exhaust gas temperature by the alcohol in the fuel, the fuel injection amount is not increased to the high rotation, high load region where the exhaust gas temperature becomes higher. Operate the internal combustion engine. As a result, fuel consumption can be suppressed while suppressing overheating of the catalyst and components. Here, as shown in FIGS. 6 and 7, the excess air ratio maps λ_GS, λ_AL are described in relation to the load KL of the internal combustion engine 1 and the engine speed Ne, and the region FU is a region where λ <1. It is.

  FIG. 8 is a flowchart illustrating a procedure of second fuel injection control according to the first embodiment. FIG. 9 is an explanatory diagram of a method for switching the excess air ratio map in the second fuel injection control according to the first embodiment. The second fuel injection control can be realized by using the engine ECU 7 shown in FIG. 1 as a fuel injection control device. In executing the second fuel injection control according to the present embodiment, in step S201, the fuel injection condition setting unit 74 of the engine ECU 7 acquires the alcohol concentration Ce of the fuel in the fuel distribution pipe 25 detected by the alcohol concentration sensor 29. To do.

  Next, in step S202, the fuel injection condition setting unit 74 determines whether or not the excess air ratio map λ_AL used when the alcohol concentration of the fuel is equal to or higher than a predetermined threshold is being used. When it is determined Yes in step S202, that is, when the fuel injection condition setting unit 74 determines that the excess air ratio map λ_AL is used, the process proceeds to step S203. In step S203, the fuel injection condition setting unit 74 of the engine ECU 7 determines whether or not the alcohol concentration Ce acquired in step S201 is equal to or higher than a third threshold value Ce3 that is a predetermined threshold value.

  When it is determined Yes in step S203, that is, when the fuel injection condition setting unit 74 determines that Ce ≧ Ce3, it is determined that the concentration of alcohol having a high effect of lowering the temperature of exhaust gas compared to gasoline is high. it can. In this case, overheating of the catalyst and parts can be suppressed even if the region where the fuel increase is not performed is expanded as compared with gasoline. In this case, the process proceeds to step S204, and the fuel injection condition setting unit 74 continues to use the excess air ratio map λ_AL set as the excess air ratio map used for the fuel injection control.

  When it is determined No in step S203, that is, when the fuel injection condition setting unit 74 determines that Ce <Ce3, it is determined that the concentration of alcohol having a high effect of reducing the temperature of the exhaust gas is lower than that of gasoline. it can. In this case, if the excess air ratio map λ_AL corresponding to the fuel having a high alcohol concentration is used, the temperature of the exhaust gas may exceed the allowable value. Therefore, the process proceeds to step S205, and the fuel injection condition setting unit 74 sets the excess air ratio map λ_GS used when the alcohol concentration of the fuel is smaller than a predetermined threshold as the excess air ratio map used for the fuel injection control. When the excess air ratio map used for the fuel injection control is set, the process proceeds to step S206, and the fuel injection control unit 75 of the engine ECU 7 controls the fuel injection timing of the fuel injection valve 21 using the set excess air ratio map. .

  If it is determined No in step S202, that is, if the fuel injection condition setting unit 74 determines that the excess air ratio map λ_GS is used, the process proceeds to step S207. In step S207, the fuel injection condition setting unit 74 of the engine ECU 7 determines whether or not the alcohol concentration Ce acquired in step S201 is equal to or higher than a fourth threshold value Ce4 that is a predetermined threshold value.

  When it is determined No in step S207, that is, when the fuel injection condition setting unit 74 determines that Ce <Ce4, it is determined that the concentration of alcohol having a high effect of lowering the temperature of exhaust gas is lower than that of gasoline. it can. In this case, if the excess air ratio map λ_AL corresponding to the fuel having a high alcohol concentration is used, the temperature of the exhaust gas may exceed the allowable value. For this reason, the process proceeds to step S205, where the fuel injection condition setting unit 74 uses the excess air ratio map λ_GS used when the alcohol concentration of the fuel is smaller than a predetermined threshold as shown in FIG. Set as a rate map.

  When it is determined Yes in step S202, that is, when the fuel injection condition setting unit 74 determines that Ce ≧ Ce4, it is determined that the concentration of alcohol having a high effect of reducing the temperature of the exhaust gas compared to gasoline is high. it can. In this case, overheating of the catalyst and parts can be suppressed even if the region where the fuel increase is not performed is expanded as compared with gasoline. In this case, the process proceeds to step S204, and the fuel injection condition setting unit 74 continues to use the excess air ratio map λ_AL set as the excess air ratio map used for the fuel injection control. Since the procedure after the excess air ratio map used for the fuel injection control is set is as described above, the description thereof is omitted.

  Here, a method for setting the excess air ratio map based on the alcohol concentration of the fuel will be described with reference to FIG. In the present embodiment, the fourth threshold value Ce4 is used as the alcohol concentration when changing from the excess air ratio map λ_GS to λ_AL (solid line E in FIG. 9), and when changing from the excess air ratio map λ_AL to λ_GS (in FIG. 9). The third threshold value Ce3 is used as the alcohol concentration of the alternate long and short dash line F). That is, the third threshold value Ce3 is used as the alcohol concentration when the excess air ratio map λ_AL in the high alcohol concentration fuel is changed to the excess air ratio map λ_GS in the low alcohol concentration fuel, and the excess air ratio map λ_GS in the low alcohol concentration fuel is increased. The fourth threshold value Ce4 is used as the alcohol concentration when changing to the excess air ratio map λ_AL in the alcohol-concentrated fuel. Here, Ce3 <Ce4.

  As described above, when the excess air ratio map λ_AL in the high alcohol concentration fuel is changed to the excess air ratio map λ_GS in the low alcohol concentration fuel, the excess air ratio map λ_GS in the low alcohol concentration fuel is changed to the excess air ratio in the high alcohol concentration fuel. The threshold value of the alcohol concentration is changed depending on the case of changing to the map λ_AL. This suppresses control hunting in switching of the excess air ratio map and realizes stable fuel injection control.

  As described above, in the second fuel injection control according to the present embodiment, the region in which the fuel is increased beyond the fuel injection amount with respect to the stoichiometric air-fuel ratio is changed based on the alcohol concentration of the fuel. As a result, in the case of fuel with a high alcohol concentration, by reducing the exhaust gas temperature by the alcohol in the fuel, the fuel injection amount is not increased to the high rotation, high load region where the exhaust gas temperature becomes higher. The internal combustion engine can be operated. As a result, fuel consumption can be suppressed while suppressing overheating of the catalyst and components.

(Embodiment 2)
The second embodiment is characterized in that, based on the alcohol concentration of the fuel, a period in which the time when the intake valve is open and the time when the exhaust valve is closed, that is, the valve overlap is changed. Here, the valve overlap control according to the second embodiment can be applied to the internal combustion engine 1 according to the first embodiment described above.

  FIG. 10 is a conceptual diagram illustrating valve overlap. FIGS. 11 and 12 are explanatory diagrams showing a valve overlap setting map used in the second embodiment. FIG. 10 shows a curve CA_IN indicating the valve opening of the intake valve 41 of the internal combustion engine 1 shown in FIG. 1 and a curve CA_EX indicating the valve opening of the exhaust valve 42. The valve overlap is a period (θc−θo) in which the timing θo when the intake valve 41 of the internal combustion engine 1 shown in FIG. 1 opens and the timing θc when the exhaust valve 42 closes overlap. When the valve overlap is increased, fuel consumption can be suppressed by reducing pumping loss and internal EGR (Exhaust Gas Recirculation). The internal combustion engine 1 shown in FIG. 1 can change the valve overlap using the intake valve timing changing mechanism 45 and the exhaust valve timing changing mechanism 47. Thereby, the fuel consumption is suppressed by changing the valve overlap according to the operating condition of the internal combustion engine 1.

  In an internal combustion engine that uses gasoline as fuel, if the valve overlap is large, the amount of PM contained in the combustion gas in the in-cylinder combustion space 30B of the internal combustion engine 1 shown in FIG. This may contribute to a deposit on the path 5 (referred to as an intake deposit). Therefore, under operating conditions in which the amount of PM generated is large, the valve overlap is limited by using the intake valve timing changing mechanism 45 and the exhaust valve timing changing mechanism 47 to suppress the intake deposit. However, since the valve overlap is limited, the effect of suppressing the fuel consumption is reduced accordingly. On the other hand, since alcohol has a small amount of PM contained in combustion gas, it has a property that intake deposits are reduced even with the same valve overlap as when only gasoline is used.

  In the present embodiment, the valve overlap is changed based on the alcohol concentration of the fuel. More specifically, a valve overlap map VT_GS (FIG. 11) used when the alcohol concentration of the fuel is smaller than a predetermined threshold and a valve overlap map used when the alcohol concentration of the fuel is equal to or higher than the predetermined threshold. A valve overlap map VT_AL (FIG. 12) is prepared in which the region in which the valve overlap is increased is larger than VT_GS. Then, the valve overlap map VT_GS and the valve overlap map VT_AL are switched and used according to the alcohol concentration of the fuel. As a result, in the case of a fuel with a high alcohol concentration, fuel consumption can be suppressed by expanding the valve overlap region while suppressing intake deposits by alcohol in the fuel.

  Here, as shown in FIGS. 11 and 12, the valve overlap maps VT_GS and VT_AL are described in relation to the load KL of the internal combustion engine 1 and the engine speed Ne. Regions where the valve overlap is larger than usual are OL1, OL2, and OL3. OL1, OL2, and OL3 each represent the size of the valve overlap, and OL1 <OL2 <OL3.

  FIG. 13 is a flowchart illustrating a procedure of intake / exhaust valve opening / closing control according to the second embodiment. FIG. 14 is an explanatory diagram of a method for switching the valve overlap map. The intake / exhaust valve opening / closing control according to the second embodiment can be realized by using the engine ECU 7 shown in FIG. 1 as an intake / exhaust valve opening / closing control device. In executing the intake / exhaust valve opening / closing control according to the present embodiment, in step S301, the fuel injection condition setting unit 74 of the engine ECU 7 acquires the alcohol concentration Ce of the fuel in the fuel distribution pipe 25 detected by the alcohol concentration sensor 29. To do.

  Next, in step S302, the fuel injection condition setting unit 74 determines whether or not the valve overlap map VT_AL used when the alcohol concentration of the fuel is equal to or higher than a predetermined threshold is being used. When it is determined Yes in step S302, that is, when the fuel injection condition setting unit 74 determines that the valve overlap map VT_AL is used, the process proceeds to step S303. In step S303, the fuel injection condition setting unit 74 of the engine ECU 7 determines whether or not the alcohol concentration Ce acquired in step S301 is equal to or higher than a fifth threshold value Ce5 that is a predetermined threshold value.

  When it is determined Yes in step S303, that is, when the fuel injection condition setting unit 74 determines that Ce ≧ Ce5, it can be determined that the concentration of alcohol with a small intake deposit is higher than that of gasoline. In this case, the intake deposit can be suppressed even if the region where the valve overlap is increased is larger than that of gasoline. In this case, the process proceeds to step S304, and the fuel injection condition setting unit 74 continues to use the valve overlap map VT_AL set as a map used for intake / exhaust valve opening / closing control.

  When it is determined No in step S303, that is, when the fuel injection condition setting unit 74 determines that Ce <Ce5, it can be determined that the concentration of alcohol with a small intake deposit is lower than that of gasoline. In this case, if the valve overlap map VT_AL corresponding to the fuel with a high alcohol concentration is used, the intake deposit may increase. In this case, the process proceeds to step S305, and the fuel injection condition setting unit 74 uses, as shown in FIG. 14, the valve overlap map VT_GS used when the alcohol concentration of the fuel is smaller than a predetermined threshold value for intake / exhaust valve opening / closing control. Set as a valve overlap map. When the valve overlap map used for fuel injection control is set, the process proceeds to step S306. In step S306, the intake / exhaust valve control unit 76 of the engine ECU 7 controls the intake valve timing change mechanism 45 and the exhaust valve timing change mechanism 47 of the internal combustion engine 1 using the set valve overlap map, and the intake valve 41 And the opening / closing timing of the exhaust valve 42 is controlled.

  If it is determined No in step S302, that is, if the fuel injection condition setting unit 74 determines that the valve overlap map VT_GS is used, the process proceeds to step S307. In step S307, the fuel injection condition setting unit 74 of the engine ECU 7 determines whether or not the alcohol concentration Ce acquired in step S301 is equal to or higher than a sixth threshold value Ce6 that is a predetermined threshold value.

  When it is determined No in step S307, that is, when the fuel injection condition setting unit 74 determines that Ce <Ce4, it can be determined that the concentration of alcohol with a small intake deposit is lower than that of gasoline. In this case, if the valve overlap map VT_AL corresponding to the fuel with a high alcohol concentration is used, the intake deposit may increase. Therefore, the process proceeds to step S305, and the fuel injection condition setting unit 74 sets the valve overlap map VT_GS used when the alcohol concentration of the fuel is smaller than a predetermined threshold as the valve overlap map used for intake / exhaust valve opening / closing control. .

  When it is determined Yes in step S307, that is, when the fuel injection condition setting unit 74 determines that Ce ≧ Ce6, it can be determined that the concentration of alcohol with a small intake deposit is higher than that of gasoline. In this case, the intake deposit can be suppressed even if the region where the valve overlap is increased is larger than that of gasoline. In this case, the process proceeds to step S304, and the fuel injection condition setting unit 74 continues to use the valve overlap map VT_AL set as the valve overlap map used for intake / exhaust valve control. Since the procedure after the valve overlap map used for the intake / exhaust valve opening / closing control is set is as described above, the description thereof is omitted.

  Here, a technique for setting the valve overlap map based on the alcohol concentration of the fuel will be described with reference to FIG. In this embodiment, the sixth threshold value Ce6 is used as the alcohol concentration when the valve overlap map VT_GS is changed to VT_AL (solid line G in FIG. 14), and the valve overlap map VT_AL is changed to VT_GS (FIG. 14). The fifth threshold value Ce5 is used as the alcohol concentration of the alternate long and short dash line H). That is, the fifth threshold Ce5 is used as the alcohol concentration when changing the valve overlap map VT_AL in the high alcohol concentration fuel to the valve overlap map VT_GS in the low alcohol concentration fuel, and the valve overlap map VT_GS in the low alcohol concentration fuel is increased. The sixth threshold value Ce6 is used as the alcohol concentration when changing to the valve overlap map VT_AL in the alcohol concentration fuel. Here, Ce5 <Ce6.

  As described above, when the valve overlap map VT_AL for the high alcohol concentration fuel is changed to the valve overlap map VT_GS for the low alcohol concentration fuel, the valve overlap map VT_GS for the low alcohol concentration fuel is changed to the valve overlap map VT_GS for the low alcohol concentration fuel. The threshold value of the alcohol concentration is changed depending on the case of changing to the map VT_AL. As a result, the control hunting in switching the valve overlap map is suppressed, and stable intake / exhaust valve opening / closing control can be realized.

  As described above, in the present embodiment, the valve overlap is changed based on the alcohol concentration of the fuel. As a result, in the case of a fuel with a high alcohol concentration, fuel consumption can be suppressed by expanding the valve overlap region while suppressing intake deposits by alcohol in the fuel.

  As described above, the fuel injection control device and the internal combustion engine of the internal combustion engine according to the present invention are useful for an internal combustion engine that can use alcohol fuel, and particularly suppress the generation of PM and smoke, and the oil generated by the fuel. Suitable for suppressing dilution.

1 is a schematic configuration diagram illustrating a configuration of an internal combustion engine according to a first embodiment. It is a schematic diagram for demonstrating fuel-injection time. It is explanatory drawing which shows the relationship between fuel-injection time and a cooling water temperature. 3 is a flowchart illustrating a procedure of first fuel injection control according to the first embodiment. It is explanatory drawing of the method of determining the cooling water temperature which switches the warming-up time retarded injection end timing of the 1st fuel injection control which concerns on Embodiment 1. FIG. It is explanatory drawing which shows the excess air ratio map used by 2nd fuel injection control. It is explanatory drawing which shows the excess air ratio map used by 2nd fuel injection control. 3 is a flowchart illustrating a procedure of second fuel injection control according to the first embodiment. It is explanatory drawing of the method of switching an excess air ratio map in the 2nd fuel injection control which concerns on Embodiment 1. FIG. It is a conceptual diagram explaining valve overlap. It is explanatory drawing which shows the valve overlap setting map used in Embodiment 2. It is explanatory drawing which shows the valve overlap setting map used in Embodiment 2. 6 is a flowchart illustrating a procedure of intake / exhaust valve opening / closing control according to the second embodiment. It is explanatory drawing of the method of switching a valve overlap map.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Fuel supply apparatus 3 Internal combustion engine main body 4 Valve apparatus 5 Intake path 6 Exhaust path 7 Engine ECU
DESCRIPTION OF SYMBOLS 21 Fuel injection valve 22 Fuel tank 25 Fuel distribution pipe 29 Alcohol concentration sensor 30 Cylinder 30B Cylinder combustion space 30C Crankcase 30iw Cylinder inner wall 31 Cylinder block 32 Cylinder head 33 Piston 34 Connecting rod 35 Crankshaft 36 Spark plug 39 Crank angle sensor 45 Intake valve timing changing mechanism 47 Exhaust valve timing changing mechanism 54 Intake passage 62 Exhaust gas passage 65 Cooling water temperature sensor 72 Processing unit 73 Storage unit 74 Fuel injection condition setting unit 75 Fuel injection control unit 76 Intake / exhaust valve control unit

Claims (8)

Controlling fuel injection of an internal combustion engine having a fuel injection valve that can use at least alcohol fuel and injects fuel directly into the combustion space in the cylinder,
A fuel injection control device for an internal combustion engine, wherein a fuel injection timing of an intake stroke before completion of warming-up of the internal combustion engine is delayed from a fuel injection timing of intake stroke after completion of warm-up of the internal combustion engine.   Based on the alcohol concentration of the fuel, the warm-up retarded injection end timing for ending the control for delaying the fuel injection timing of the intake stroke before the warm-up completion from the fuel injection timing of the intake stroke after the warm-up is completed. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel injection control device is changed.   3. The warm-up retarded injection end timing is advanced when the alcohol concentration of the fuel is equal to or higher than a predetermined threshold, compared to when the alcohol concentration of the fuel is smaller than the threshold. A fuel injection control device for an internal combustion engine.   The internal combustion engine fuel according to any one of claims 1 to 3, wherein a region in which the internal combustion engine is operated at an air / fuel ratio smaller than a stoichiometric air / fuel ratio is changed based on an alcohol concentration of the fuel. Injection control device. In an internal combustion engine in which at least alcohol fuel can be used and fuel is directly injected into a combustion space in a cylinder in which a piston reciprocates,
When injecting the fuel in the intake stroke of the internal combustion engine, the fuel that injects the fuel into the combustion space by retarding the timing of injecting the fuel before the completion of warm-up than after the completion of warm-up An internal combustion engine comprising an injection valve. The fuel injection valve is
The warm-up retarded injection end timing is terminated based on the alcohol concentration of the fuel. The control is terminated so that the fuel injection timing before the completion of the warm-up is delayed rather than after the warm-up completion. An internal combustion engine according to claim 5. The fuel injection valve is
The warm-up retarded injection end timing is made earlier when the alcohol concentration of the fuel is equal to or higher than a predetermined threshold value, compared to when the alcohol concentration of the fuel is smaller than the threshold value. The internal combustion engine described in 1. The fuel injection valve is
The internal combustion engine according to any one of claims 5 to 7, wherein a region in which the internal combustion engine is operated at an air-fuel ratio smaller than a stoichiometric air-fuel ratio is changed based on an alcohol concentration of the fuel.

Images