JP2013142301A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently hold combustibility, even if an estimation error of an alcohol concentration exists when starting.SOLUTION: An ECU 50 injects fuel exceeding an allowable limit in a transport delay out of fuel tried to be injected from an intake passage injection valve 26, from a cylinder injection valve 28 as a transport delay increase quantity, when simultaneously using intake passage injection and cylinder injection when starting an engine. Thus, even when an estimation error is caused when estimating an alcohol concentration in the fuel, a cylinder injection quantity for improving startability can be increased. Thus, influence of the estimation error on an intake passage injection quantity and a transport delay increase quantity is restrained, and starting time combustibility can be excellently held. A variation in the air-fuel ratio and the deterioration in exhaust emission caused by the transport delay of the intake passage injection are restrained, and the startability and an exhaust characteristic can be improved.

Description

  The present invention relates to a control device for an internal combustion engine that is mounted on a vehicle such as an FFV (Flexible-Fuel Vehicle) and uses alcohol fuel.

  As a conventional technique, for example, as disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-214415), it is applied to an internal combustion engine using alcohol fuel, and fuel is supplied from an intake passage injection valve to an intake passage (intake port). 2. Description of the Related Art There is known a control device for an internal combustion engine that executes intake passage injection for injection and in-cylinder injection for injecting fuel into a combustion chamber (in-cylinder) from an in-cylinder injection valve. In the prior art, in-cylinder injection is executed at the time of starting, and after starting, injection division control that selectively uses intake passage injection and in-cylinder injection is executed according to the operating state. According to the in-cylinder injection, the start can be performed earlier than the intake passage injection.

  On the other hand, as another conventional technique, Patent Document 2 (Japanese Patent Laid-Open No. 2009-191806) discloses an injection in consideration of a transport delay until the injected fuel reaches the cylinder in the intake passage injection. Control for increasing the amount of fuel (increase in transport delay) is disclosed. In this control, an increase value of the injected fuel is set according to the alcohol concentration in the fuel.

JP 2006-214415 A JP 2009-191806 A JP 2011-1848 A

  In the above-described prior art, when the alcohol concentration in the fuel is high at the time of engine start (starting), that is, when a large amount of fuel injection is required, the fuel may not be completely injected by in-cylinder injection alone. . In order to avoid this state, for example, a method in which in-cylinder injection is executed at the initial stage of starting and then intake passage injection is used in combination is considered. However, at the time of start-up, the water temperature is often low and it is difficult for the alcohol fuel to vaporize. For this reason, when performing intake passage injection, as described in Patent Document 2, in consideration of transport delay of intake passage injection, control for increasing the intake passage injection amount in accordance with the alcohol concentration in the fuel (Transport delay increase) needs to be executed.

  On the other hand, when the alcohol concentration in the fuel is changed due to refueling or the like at the time of starting, a deviation occurs between the estimated value (detected value) of the alcohol concentration recognized on the control device side and the actual alcohol concentration. There is a case. In this case, the intake passage injection amount and the transport delay increase amount are set based on the alcohol concentration including an error, and there is a problem that the combustibility deteriorates.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is an internal combustion engine that can maintain good combustibility even when there is an estimation error in alcohol concentration at the start. It is to provide an engine control device.

1st invention is mounted in the internal combustion engine which uses gasoline and alcohol fuel, and the intake passage injection valve which injects fuel to an intake passage,
An in-cylinder injection valve mounted on the internal combustion engine for injecting fuel into the cylinder;
Alcohol concentration acquisition means for acquiring the alcohol concentration in the fuel;
In-cylinder injection control means for performing in-cylinder injection by driving the in-cylinder injection valve when starting the engine,
When it is determined that fuel injection into the intake passage is necessary, intake passage injection combined means for driving the intake passage injection valve and using intake passage injection together;
Of the fuel to be injected from the intake passage injection valve at the start of the engine, the fuel whose transport delay from injection until it reaches the cylinder exceeds the allowable limit is injected from the cylinder injection valve as an increase in transport delay. Transportation delay increase transfer means,
It is characterized by providing.

  According to the second invention, the increase in the transport delay is set so as to increase as the alcohol concentration in the fuel increases.

  According to the third invention, the increase in the transport delay is configured to gradually decrease as the number of cycles at the start of the engine increases.

  According to the fourth aspect of the invention, the degree of decrease in the transport delay increase is set so as to increase as the alcohol concentration in the fuel increases.

  According to the fifth aspect of the present invention, when the alcohol concentration in the fuel is lower than a predetermined determination value, the fuel corresponding to the increase in the transport delay is injected from the intake passage injection valve.

  According to the first aspect of the present invention, in the cycle (operating region) in which intake passage injection and in-cylinder injection are used in combination, even if an alcohol concentration estimation error occurs, the in-cylinder injection amount that improves startability is increased. Can do. As a result, it is possible to suppress the influence of the estimation error on the intake passage injection amount and the increase in the transport delay, and to keep the combustibility at the start at a good level. Further, it is possible to suppress air-fuel ratio fluctuations and exhaust emission deterioration caused by transport delay of intake passage injection, and to improve startability and exhaust characteristics.

  According to the second invention, as the alcohol concentration in the fuel is higher, the transport delay increase can be set to a larger value. That is, since the intake passage injection amount tends to increase as the alcohol concentration increases, the increase in the transport delay can be appropriately changed in accordance with the alcohol concentration by increasing the increase in the transport delay accordingly.

  According to the third aspect of the present invention, the increase in transport delay can be gradually reduced as the number of cycles at the start of the engine increases. As a result, a sudden change in the increase in transport delay can be prevented, so that the air-fuel ratio can be continuously changed in a stable state, and combustibility and exhaust emission can be further improved.

  According to the fourth invention, as the alcohol concentration in the fuel is higher, the degree of decrease in the transport delay increase can be set to a larger value. As a result, the higher the alcohol concentration, the greater the increase in transport delay can be reduced for each cycle. Therefore, it is possible to suppress the over-richness of the air-fuel ratio that occurs when the temperature of the fuel with a high alcohol concentration rises, while ensuring a necessary and sufficient amount of increase in transport delay.

  According to the fifth aspect of the present invention, when the alcohol concentration in the fuel is equal to or less than the predetermined determination value, the fuel corresponding to the transport delay increase amount can be injected from the intake passage injection valve. That is, when the alcohol concentration in the fuel is lower than the determination value, the intake passage injection amount is small, so even if there is an estimation error in alcohol concentration, the error that occurs in the intake passage injection amount due to the estimation error is It is smaller than when the alcohol concentration is high. In this case, by ignoring the estimation error of the alcohol concentration and adding the fuel corresponding to the increase in the transport delay to the target intake passage injection, the uniformity of the air-fuel mixture can be improved with priority, and PM The discharge of (particulate matter) can be suppressed.

It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is explanatory drawing which shows the fuel-injection state of each cylinder, when the fuel (gasoline) whose alcohol concentration is zero is used. It is explanatory drawing which shows the fuel-injection state of each cylinder at the time of engine starting in the case of using alcohol fuel. In Embodiment 1 of this invention, it is a flowchart of the control performed by ECU. In Embodiment 2 of this invention, it is explanatory drawing which shows the fuel-injection state of each cylinder at the time of engine starting. In Embodiment 3 of this invention, it is explanatory drawing which shows the fuel-injection state of each cylinder at the time of engine starting. In Embodiment 4 of this invention, it is explanatory drawing which shows the fuel-injection state of each cylinder at the time of engine starting.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram for explaining a system configuration according to the first embodiment of the present invention. The system of the present embodiment includes a multi-cylinder engine 10 as an internal combustion engine mounted on a vehicle such as an FFV. The engine 10 can use alcohol fuel and gasoline including, for example, methanol and ethanol. FIG. 1 exemplifies one cylinder among a plurality of cylinders mounted on the engine 10. Each cylinder of the engine 10 has a combustion chamber 14 formed by a piston 12, and the piston 12 is connected to a crankshaft 16. Further, the engine 10 includes an intake passage 18 that sucks intake air into each cylinder. The intake passage 18 is provided with an electronically controlled throttle valve 20 that adjusts the amount of intake air.

  On the other hand, the engine 10 includes an exhaust passage 22 that exhausts exhaust gas of each cylinder, and the exhaust passage 22 is provided with a catalyst 24 such as a three-way catalyst that purifies the exhaust gas. Each cylinder of the engine has an intake passage injection valve 26 for injecting fuel into the intake passage 18 (intake port), an in-cylinder injection valve 28 for injecting fuel into the combustion chamber 14 (in-cylinder), and an air-fuel mixture. An ignition plug 30 for igniting, an intake valve 32 for opening and closing the intake passage 18 with respect to the inside of the cylinder, and an exhaust valve 34 for opening and closing the exhaust passage 22 with respect to the inside of the cylinder are provided.

  The system of the present embodiment includes a sensor system including various sensors necessary for engine control, and an ECU (Engine Control Unit) 50 that controls the operating state of the engine. First, the sensor system will be described. The crank angle sensor 40 outputs a signal synchronized with the rotation of the crankshaft 16, and the air flow sensor 42 detects the intake air amount of the engine. The water temperature sensor 44 detects the temperature of the engine cooling water (engine water temperature) as an example of the engine temperature, and the intake air temperature sensor 46 detects the temperature of the intake air (outside air temperature). The alcohol concentration sensor 48 detects the alcohol concentration in the fuel, and constitutes the alcohol concentration acquisition means of the present embodiment. Various other sensors are included in the sensor system, and these sensors are connected to the input side of the ECU 50. In addition, an actuator such as a throttle valve 20, fuel injection valves 26 and 28, and a spark plug 30 is connected to the output side of the ECU 50.

  Then, the ECU 50 drives each actuator based on engine operation information detected by the sensor system, and performs operation control. Specifically, based on the output of the crank angle sensor 40, cylinder discrimination for discriminating the stroke of each cylinder (the position of the piston 12) is executed, and the engine speed (engine speed) and the crank angle are detected. To do. Note that cylinder discrimination is performed only at the start. Further, the ECU 50 detects the intake air amount by the air flow sensor 42 and calculates a load factor (engine load) based on the engine speed and the intake air amount. Then, based on parameters such as the intake air amount, the engine load, the engine water temperature, the alcohol concentration in the fuel, and the acceleration / deceleration state of the engine, the total fuel injection amount is calculated by a known method.

  Here, the total fuel injection amount is a target value (target intake passage injection amount) of the fuel injection amount injected from the intake passage injection valve 26 (intake passage injection), and injection (in-cylinder injection) from the in-cylinder injection valve 28. This is the sum of the fuel injection amount and the target value (target in-cylinder injection amount). Then, the ECU 50 executes one or both of intake passage injection and in-cylinder injection according to the operating state, temperature state, and the like of the engine. More specifically, when either one of the injections is executed, an amount of fuel corresponding to the total fuel injection amount is injected from the corresponding injection valve. Moreover, when performing both injections, the ratio (injection ratio) of the fuel injection amount by the injection valves 26 and 28 is calculated based on the operating state of the engine or the like. Based on the injection ratio and the total fuel injection amount, the target intake passage injection amount and the target in-cylinder injection amount are calculated, and fuel corresponding to these target injection amounts is injected from the injection valves 26 and 28, respectively. . Further, the ECU 50 determines the ignition timing according to the operating state of the engine and drives the spark plug 30 to burn the air-fuel mixture in each cylinder.

[Features of Embodiment 1]
Alcohol fuel has low volatility and tends to increase the fuel injection amount, and this tendency is particularly noticeable at the time of starting. For this reason, at the time of start-up, there is a demand for improving the combustibility by directly injecting alcohol fuel into the cylinder. However, when the alcohol concentration in the fuel is high, the fuel may not be completely injected only by the in-cylinder injection, and the intake passage injection must be used together. In this case, for example, in-cylinder injection is preferably executed in the first cycle after cylinder discrimination, and intake passage injection is preferably used in combination after the second cycle. However, when the intake passage injection is executed, there is a time difference (transport delay) between the time when the fuel is injected and the time when it reaches the cylinder. For this reason, in the present embodiment, of the fuel to be injected from the intake passage injection valve 26 when the engine is started, the fuel whose transport delay exceeds the allowable limit is injected from the in-cylinder injection valve 28 as an increase in transport delay.

  Here, the fuel whose transport delay exceeds the allowable limit is the fuel that cannot be burned in the intended cycle because it is delayed from reaching the cylinder due to the transport delay even if it is injected from the intake passage injection valve 26. Defined. More specifically, when starting with alcohol fuel, the target intake passage injection amount tends to increase, and this tendency becomes more pronounced as the alcohol concentration in the fuel is higher and the engine temperature at the time of starting is lower. . When the target intake passage injection amount is extremely increased, the fuel injection period becomes longer. For example, the fuel injected at the end of the injection period may flow into the cylinder before the end of the intake stroke. It is not possible, and the transport delay exceeds the allowable limit. Since such fuel does not contribute to combustion in the intended cycle, it becomes a factor that deteriorates the controllability of the air-fuel ratio and the exhaust emission.

  Therefore, in the present embodiment, when the intake passage injection and the in-cylinder injection are used at the time of starting the engine, a control (transport delay correction control) is performed in consideration of the transport delay of the injected fuel. In the transport delay correction control, the fuel whose transport delay exceeds the allowable limit in the target intake passage injection amount is not added to the target intake passage injection amount (subtracted from the target intake passage injection amount), and this fuel is used as the transport delay increase amount. Add to the target in-cylinder injection amount. Hereinafter, the fuel injection control of the present embodiment will be specifically described with reference to FIGS. 2 and 3. In these drawings, a six-cylinder engine is taken as an example, and numbers (# 1 to # 6) are assigned to the respective cylinders in the order in which fuel injection is performed.

(When using gasoline)
FIG. 2 is an explanatory view showing the fuel injection state of each cylinder when fuel (gasoline) having a zero alcohol concentration is used. When using gasoline, at least in the first cycle after engine start (after cylinder discrimination), only in-cylinder injection is executed, and fuel is directly injected into the cylinder to improve startability. Next, in the second cycle, intake passage injection and in-cylinder injection are used in combination. In particular, at a low temperature start in a state where the alcohol concentration in the fuel is high, the increase in the total fuel injection amount becomes remarkable, and the required amount of fuel may not be completely injected only by the in-cylinder injection. In consideration of such points, intake passage injection and in-cylinder injection are used together in the second cycle. When the alcohol concentration in the fuel is lower than the reference value that can be handled only by in-cylinder injection, the in-cylinder injection is performed without performing the intake passage injection after the second cycle. Also good.

  In the first intake passage injection, since a relatively large amount of injected fuel adheres to the wall surface of the intake passage, the amount of fuel contributing to combustion tends to be relatively reduced. For this reason, in the second cycle, control for adding the wall surface attached fuel amount to the target intake passage injection amount (wall surface attached amount correction control) is executed. Here, the amount of fuel attached to the wall surface corresponds to the amount of fuel that adheres to the wall surface of the fuel injected into the intake passage, and is known based on the target intake passage injection amount, the engine water temperature, the alcohol concentration in the fuel, and the like. Calculated by the method. In the third and subsequent cycles, for example, it is considered that the fuel adhering to the wall surface of the intake passage and the fuel vaporized from the wall surface reach a certain equilibrium state, so the wall surface adhesion amount correction control is stopped.

(When using alcohol fuel)
Next, FIG. 3 is an explanatory view showing a fuel injection state of each cylinder at the time of starting the engine when alcohol fuel is used. Even when alcohol fuel is used, in-cylinder injection is executed in the first cycle, as in the case of gasoline. In addition, after the second cycle, intake passage injection and in-cylinder injection are used together, and wall surface adhesion amount correction control is executed in the second cycle. However, in the case of alcohol fuel, the target intake passage injection amount is larger than that of gasoline. Therefore, in the second cycle, even if the target intake passage injection amount is injected from the intake passage injection valve 26, A fuel that is not in time for combustion, that is, a fuel whose transport delay exceeds an allowable limit, is generated. For this reason, the ECU 50 executes transport delay correction control.

  In the transport delay correction control, first, the amount of fuel whose transport delay exceeds the allowable limit among the target intake passage injection amount is calculated as the transport delay increase amount. Then, the target intake passage injection amount is decreased by the increase in transport delay, and the target in-cylinder injection amount is increased by the increase in transport delay. Here, the increase in the transport delay is achieved by using, for example, a known calculation model that models the behavior of the fuel injected into the intake passage until it reaches the cylinder, and the engine speed, load factor, target intake passage injection, and the like. It is calculated on the basis of parameters such as the amount, the alcohol concentration in the fuel, and the time constant corresponding to the fuel transportation delay. FIG. 3 illustrates the case where the transport delay correction control is executed in the second and third cycles, for example, and the transport delay increase amount (outlined portion) is added to the in-cylinder injection amount.

  According to the transport delay correction control, in the cycle (operating region) in which the intake passage injection and the in-cylinder injection are used together, the in-cylinder injection amount that improves the startability can be increased even when an estimation error of the alcohol concentration occurs. Can do. As a result, it is possible to suppress the influence of the estimation error on the intake passage injection amount and the increase in the transport delay, and to keep the combustibility at the start at a good level. Further, the fuel whose transport delay exceeds the allowable limit in the target intake passage injection amount can be added to the target in-cylinder injection amount as the transport delay increase amount, and this fuel can be subtracted from the target intake passage injection amount. That is, even when the alcohol concentration in the fuel is high, the fuel corresponding to the transport delay in the intake passage injection can be transferred to the in-cylinder injection that does not cause the transport delay. Further, by evaporating on the intake port side, it is possible to reduce the amount of fuel that causes air-fuel ratio roughening from flowing into the cylinder. Therefore, it is possible to suppress air-fuel ratio fluctuations and exhaust emission deterioration caused by transport delay of intake passage injection, and to improve startability and exhaust characteristics.

  The transport delay correction control is executed when, for example, the alcohol concentration in the fuel is equal to or higher than a predetermined determination value. This determination value is set corresponding to the minimum value of the alcohol concentration that causes a transport delay exceeding the allowable limit. When the alcohol concentration is equal to or higher than the determination value, the target intake passage injection amount increases, and fuel is generated in which the transport delay exceeds the allowable limit. Therefore, transport delay correction control is executed. On the other hand, when the alcohol concentration is lower than the determination value, the target intake passage injection amount does not increase so that the transport delay exceeding the allowable limit occurs, and therefore, the transport delay correction control is not executed, which corresponds to the transport delay increase amount. Fuel is injected from the intake passage injection valve 26. Thereby, the following effects can be obtained.

  When the alcohol concentration in the fuel is lower than the determination value, since the intake passage injection amount is small, even if there is an estimation error in the alcohol concentration, the error that occurs in the intake passage injection amount due to the estimation error is the alcohol concentration. It becomes smaller compared to when it is high. In this case, by ignoring the estimation error of the alcohol concentration and adding the fuel corresponding to the increase in the transport delay to the target intake passage injection, the uniformity of the air-fuel mixture can be improved with priority, and PM The discharge of (particulate matter) can be suppressed. FIG. 3 illustrates a case where the alcohol concentration in the fuel is equal to or higher than the determination value.

  Further, the transport delay increase amount is set so as to increase as the alcohol concentration in the fuel increases. The target intake passage injection amount tends to increase as the alcohol concentration increases, and accordingly, the amount of fuel whose transport delay exceeds the allowable limit among the target intake passage injection amount also increases. Therefore, according to the present embodiment, it is possible to appropriately change the transport delay increase according to the alcohol concentration in the fuel. The transport delay correction control is executed when it is determined necessary based on the alcohol concentration in the fuel, the target intake passage injection amount, and the like. That is, the execution timing (second and third cycles) of the transport delay correction control shown in FIG. 3 is merely an example, and the present invention is not limited to this execution timing. Further, the transport delay correction control is terminated when, for example, the target intake passage injection amount is reduced to an amount that does not require the transport delay increase amount.

[Specific Processing for Realizing Embodiment 1]
Next, a specific process for realizing the above-described control will be described with reference to FIG. FIG. 4 is a flowchart of control executed by the ECU in the first embodiment of the present invention. In the routine shown in this figure, first, at step 100, it is determined whether or not the ignition switch (IG) is ON. If it is ON, the routine proceeds to step 102. In steps 102, 104, and 106, the engine water temperature ethw, the outside air (environment) temperature etha, and the alcohol concentration ealch in the fuel are calculated based on the output of the sensor system. The alcohol concentration ealch may be estimated based on the exhaust air / fuel ratio without using the alcohol concentration sensor 48.

  Next, in step 108, it is determined whether or not the starter switch is ON. If it is ON, the process proceeds to step 110. In step 110, crank angle detection and cylinder discrimination are executed based on the output of the crank angle sensor 40 while driving (starting) cranking by driving the starter motor. Next, in step 112, as described above, first, the total fuel injection amount (basic injection amount) is calculated, and the target intake passage injection amount and / or the in-cylinder injection amount are calculated according to the number of cycles. To do. In step 112, for example, in the second cycle, the wall surface attached fuel amount is calculated, and the calculation result is added to the target intake passage injection amount.

  Next, in step 114, an increase in transport delay is calculated based on the alcohol concentration in the fuel. When the alcohol concentration is equal to or higher than the determination value, the calculated transport delay increase amount is added to the target in-cylinder injection amount. When the alcohol concentration is lower than the determination value, the transport delay increase amount is added to the target intake passage injection amount. Next, in step 116, intake passage injection and / or in-cylinder injection are executed according to the calculation results of steps 112 to 114 and the number of cycles. After the engine shifts to the self-sustained operation by the above routine, either the intake passage injection or the in-cylinder injection is executed or the injection ratio is set to be variable by using both in accordance with the operating state of the engine. Blowing control is executed.

  In the first embodiment, step 116 in FIG. 4 shows a specific example of the in-cylinder injection control means and the intake passage injection combined means in claim 1, and step 114 shows a specific example of the transport delay increase transfer means. .

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, in addition to the same configuration and control as in the first embodiment, the increase in the transport delay is gradually reduced as the number of cycles at the start of the engine increases. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 2]
FIG. 5 is an explanatory diagram showing the fuel injection state of each cylinder when the engine is started in the second embodiment of the present invention. This figure illustrates the case where the alcohol concentration in the fuel is equal to or higher than the determination value (the same case as in FIG. 3). As shown in FIG. 5, in this embodiment, every time the number of cycles at the start of the engine increases (the cycle progresses), the increase in transport delay is gradually reduced. According to the present embodiment, the following operational effects can be obtained.

  In the first embodiment, when the target intake passage injection amount has decreased to an amount that does not require an increase in transport delay, the transport delay correction control is terminated and the transport delay increase is set to zero. However, when the transportation delay correction control is suddenly stopped, the air-fuel ratio changes suddenly and becomes discontinuous, which may cause the engine speed and exhaust emission to become unstable. On the other hand, in the present embodiment, as shown in FIG. 5, the transport delay increase amount, that is, the in-cylinder injection amount can be gradually decreased. Thereby, in addition to the effect by the said Embodiment 1, an air fuel ratio can be changed continuously in the stable state, and combustibility and exhaust emission can be improved more.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIG. In the present embodiment, in the transport delay correction control, a process of adding the transport delay increase amount to the intake passage injection amount when the alcohol concentration in the fuel is lower than the determination value is illustrated. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 3]
FIG. 6 is an explanatory diagram showing the fuel injection state of each cylinder when the engine is started in the third embodiment of the present invention. In the transport delay correction control, as shown in FIG. 3, when the alcohol concentration in the fuel is equal to or higher than the determination value, the transport delay increase amount is added to the target in-cylinder injection amount. On the other hand, when the alcohol concentration in the fuel is lower than the determination value, the transport delay increase is added to the target intake passage injection amount as shown in FIG. The reason for performing such processing is as described above. That is, according to the present embodiment, when the alcohol concentration in the fuel is lower than the determination value, even if there is an alcohol concentration estimation error or the like, it is ignored and transported with respect to the target intake passage injection. By adding the fuel corresponding to the delay increase, the uniformity of the air-fuel mixture can be improved with priority.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, in the transportation delay correction control, the degree of decrease in the transportation delay increase is set so as to increase as the alcohol concentration in the fuel increases. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 4]
FIG. 7 is an explanatory diagram showing the fuel injection state of each cylinder when the engine is started in the fourth embodiment of the present invention. The lower side of this figure shows the operation of adding an increase in transport delay to the intake passage injection amount of each cylinder by transport delay correction control. Further, the upper side of FIG. 7 shows an operation of gradually decreasing the transport delay increase amount added to the intake passage injection amount of each cylinder in the second cycle. As shown in this figure, in the present embodiment, as in the second embodiment, the increase in the transport delay is gradually reduced each time the number of cycles at the start of the engine increases (the cycle progresses). Then, the degree of decrease when the transport delay increase is decreased (the time decrease rate of the transport delay increase) is set so as to increase as the alcohol concentration in the fuel increases.

  According to the present embodiment, the following operational effects can be obtained. Although alcohol fuel has low volatility at low temperatures, it has the property of evaporating rapidly when the temperature exceeds the boiling point. For this reason, the higher the alcohol concentration in the fuel, the more rapidly the amount of fuel evaporation when the temperature exceeds the boiling point, and the air-fuel ratio tends to become over-rich. On the other hand, when the alcohol concentration in the fuel is low, if the increase in transportation delay is rapidly decreased, the effect of the transportation delay increase may not be sufficiently exhibited. In contrast, in this embodiment, the higher the alcohol concentration in the fuel, the greater the increase in transport delay can be reduced for each cycle. Therefore, in addition to the operational effects of the first and second embodiments, it is possible to suppress the over-richness of the air-fuel ratio that occurs when the temperature of the fuel with a high alcohol concentration rises, while ensuring a necessary and sufficient amount of transport delay increase. .

  Further, in this embodiment, since the increase in transport delay is gradually decreased, the air-fuel ratio can be continuously changed in a stable state as in the second embodiment, and the combustibility and exhaust emission can be further improved. Can be improved. In the present embodiment, the case where the increase in transport delay added to the target intake passage injection amount of each cylinder is gradually reduced is illustrated. However, the present invention is not limited to this, and it is possible to gradually decrease the increase in transport delay added to the target in-cylinder injection amount of each cylinder and set the decrease rate so that the alcohol concentration in the fuel increases. Good.

10 Engine 12 Piston 14 Combustion chamber 16 Crankshaft 18 Intake passage 20 Throttle valve 22 Exhaust passage 24 Catalysts 26 and 28 Fuel injection valve 30 Spark plug 32 Intake valve 34 Exhaust valve 40 Crank angle sensor 42 Air flow sensor 44 Water temperature sensor 46 Intake temperature sensor 48 Alcohol concentration sensor (Alcohol concentration acquisition means)
50 ECU

Claims (5)

An intake passage injection valve mounted on an internal combustion engine that uses gasoline and alcohol fuel, and injects fuel into the intake passage;
An in-cylinder injection valve mounted on the internal combustion engine for injecting fuel into the cylinder;
Alcohol concentration acquisition means for acquiring the alcohol concentration in the fuel;
In-cylinder injection control means for performing in-cylinder injection by driving the in-cylinder injection valve when starting the engine,
When it is determined that fuel injection into the intake passage is necessary, intake passage injection combined means for driving the intake passage injection valve and using intake passage injection together;
Of the fuel to be injected from the intake passage injection valve at the start of the engine, the fuel whose transport delay from injection until it reaches the cylinder exceeds the allowable limit is injected from the cylinder injection valve as an increase in transport delay. Transportation delay increase transfer means,
A control device for an internal combustion engine, comprising:   The control apparatus for an internal combustion engine according to claim 1, wherein the increase in the transport delay is set so as to increase as the alcohol concentration in the fuel increases.   The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the increase in the transport delay is configured to gradually decrease as the number of cycles at the start of the engine increases.   The control apparatus for an internal combustion engine according to claim 3, wherein the degree of decrease in the increase in transport delay is set so as to increase as the alcohol concentration in the fuel increases.   5. The structure according to claim 1, wherein when the alcohol concentration in the fuel is lower than a predetermined determination value, the fuel corresponding to the increase in the transport delay is injected from the intake passage injection valve. Control device for internal combustion engine.

Images