WO2013098953A1

WO2013098953A1 - Control device for internal combustion engine

Info

Publication number: WO2013098953A1
Application number: PCT/JP2011/080253
Authority: WO
Inventors: 森田　晃司; 崇博塚越
Original assignee: トヨタ自動車株式会社
Priority date: 2011-12-27
Filing date: 2011-12-27
Publication date: 2013-07-04

Abstract

The objective of the present invention is to achieve excellent combustion in an internal combustion engine equipped with a port injection valve and an in-cylinder injection valve, even when there is a difference in the alcohol concentration of the fuel injected from these injection valves. The injection ratio that is currently set for the port injection and the in-cylinder injection is obtained. In addition, the A/F correction amount (the steady A/F deviation amount) of an E0 standard during steady operation is obtained. When the engine load changes, the amount of that change is obtained, and the temporary variation in the exhaust air-fuel ratio in conjunction with that change in the engine load is detected, and the peak value (the transient A/F deviation amount) of the E0 standard for that variation is obtained. Then, the respective alcohol concentrations for the port injection fuel and the in-cylinder injection fuel currently being used for the engine are determined by applying the steady A/F deviation amount, the amount of change in the engine load, the transient A/F deviation amount corresponding thereto, and the injection ratio, to a determination model. Using the fuel alcohol concentrations thus determined, the injection ratio is changed appropriately to achieve excellent combustion.

Description

Control device for internal combustion engine

The present invention relates to a control device for an internal combustion engine, and in particular, includes a port injection valve that injects fuel into an intake port and an in-cylinder injection valve that injects fuel into a cylinder, and changes an injection ratio by both injection valves. The present invention relates to a control apparatus for a possible internal combustion engine.

As an internal combustion engine (4-stroke reciprocating engine) for automobiles, it is possible to use multiple types of fuel, for example, hydrocarbon fuels such as gasoline and alcohol (ethanol, methanol, etc.), or a mixture of these. There are known internal combustion engines. In such an internal combustion engine, control according to the alcohol concentration of the fuel used is required. Specifically, since the calorific value per unit volume differs greatly between alcohol and gasoline, air-fuel ratio control according to the alcohol concentration of the fuel is required.

However, the alcohol concentration of the fuel used is not always known and is not always constant. Since there are a plurality of types of commercially available alcohol-mixed fuels having different alcohol concentrations, fuel with an alcohol concentration different from the fuel in the fuel tank may be added by refueling. For this reason, in an internal combustion engine in which use of an alcohol-mixed fuel is assumed, a means for knowing the alcohol concentration of the fuel used is required.

Incidentally, an alcohol concentration sensor is conventionally used as the above means. For example, Japanese Patent Laid-Open No. 2010-24996 discloses a fuel injection control device including an alcohol concentration sensor. Specifically, the engine of this device is a dual-injection internal combustion engine provided with a port injector and an in-cylinder injector, and can separately inject fuel into the port and the cylinder. It has become. An alcohol sensor is provided in the middle of the fuel supply system for supplying fuel to each injector. The alcohol sensor detects the alcohol concentration of the fuel passing through the fuel supply system. The detected alcohol concentration is used for calculating the correction amount of the fuel injection amount in the air-fuel ratio control.

Japanese Unexamined Patent Publication No. 2010-24996

However, in the case of an internal combustion engine of a type that includes both a port injection valve and an in-cylinder injection valve as in the prior art described above, the fuel injection amount from each fuel injection valve and the fuel piping from the fuel tank to each fuel injection valve Each length is different. For this reason, when fuels having different alcohol concentrations are supplied into the fuel tank, the timing at which new fuel reaches each fuel injection valve does not match, and as a result, the alcohol of fuel injected from each fuel injection valve The density will be different. In the above conventional technique, since the alcohol concentration sensor is provided in the fuel pipe nearest to the fuel tank, the alcohol concentration of the fuel injected from each fuel injection valve cannot be detected individually. For this reason, when a situation occurs in which the alcohol concentration of the fuel injected from each fuel injection valve becomes a different concentration, the air-fuel ratio correction cannot be performed accurately, which may lead to deterioration of emission and drivability. There is.

The present invention has been made to solve the above-described problems. In an internal combustion engine including a port injection valve for injecting fuel into an intake port and an in-cylinder injection valve for injecting fuel into a cylinder, To provide a control device for an internal combustion engine capable of realizing good combustion even when the alcohol concentration of fuel injected from an injection valve is different from the alcohol concentration of fuel injected from a cylinder injection valve With the goal.

In order to achieve the above object, a first invention includes a port injection valve that injects fuel into an intake port and a cylinder injection valve that injects fuel into a cylinder, and the exhaust air-fuel ratio of the internal combustion engine is a target. A control device for an internal combustion engine that performs air-fuel ratio control for controlling a fuel injection amount injected from the port injection valve and the in-cylinder injection valve so as to be an air-fuel ratio,
Means for obtaining an injection ratio between a fuel injection amount from the port injection valve and a fuel injection amount from the in-cylinder injection valve;
Means for acquiring a change amount of the load when the load of the internal combustion engine changes;
Transient A / F information acquisition means for detecting a temporary fluctuation of the exhaust air-fuel ratio that occurs when the load of the internal combustion engine changes, and acquiring information related to the peak value as transient A / F information;
Steady A / F information means for obtaining information related to the correction amount of the air-fuel ratio immediately before the load of the internal combustion engine changes as steady A / F information;
Change means for changing the injection ratio at the next fuel injection based on the load change amount, the corresponding transient A / F information, the steady A / F information, and the injection ratio at that time;
It is characterized by having.

According to a second invention, in the first invention,
The changing means is
The amount of change in load, transient A / F information, steady A / F information, and injection ratio of port injection fuel injected from the port injection valve and in-cylinder injection fuel injected from the in-cylinder injection valve A decision model that correlates alcohol concentration;
By applying the change amount of the load, the corresponding transient A / F information, the steady A / F information, and the injection ratio at that time to the determination model, the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are respectively determined. A first means for determining;
A second means for specifying an injection ratio at the next fuel injection based on the alcohol concentration of the port injection fuel and the in-cylinder injection fuel;
It is characterized by including.

According to a third invention, in the second invention,
The second means applies the change amount of the load, the steady A / F information, and the injection ratio at that time to the determination model, so that the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are equal. The transient A / F information is specified as the transient A / F reference information, the load change amount, the transient A / F reference information, the steady A / F information, and the alcohol concentration of the port injection fuel and the in-cylinder injection fuel at that time Is applied to the determination model to specify the injection ratio at the next fuel injection.

4th invention is 2nd or 3rd invention,
The steady-state A / F information acquisition means acquires, as the transient A / F information, a difference amount between the peak value and a peak value under the same condition when using gasoline fuel having an alcohol concentration of 0%. It is characterized by that.

According to a fifth invention, in any one of the second to fourth inventions,
The steady-state A / F information acquisition means obtains the difference amount between the correction amount of the air-fuel ratio and the correction amount of the air-fuel ratio under the same condition when using gasoline fuel having an alcohol concentration of 0%. / F information is obtained.

A sixth invention is any one of the first to fifth inventions,
Determining means for determining an abnormality of the port injection valve or the in-cylinder injection valve based on a load change amount, transient A / F information corresponding thereto, steady A / F information, and an injection ratio at that time; Furthermore, it is characterized by providing.

A seventh invention is the sixth invention, wherein
When the ratio of the transient A / F information to the steady A / F information is greater than a predetermined upper limit value determined based on the load change amount and the injection ratio at that time, It is characterized by determining occurrence of clogging failure of the in-cylinder injection valve.

The eighth invention is the sixth or seventh invention, wherein
When the ratio of the transient A / F information to the steady A / F information is smaller than a predetermined lower limit value determined based on the load change amount and the injection ratio at that time, It is characterized by determining the occurrence of clogging failure of the port injection valve.

According to the first aspect of the present invention, based on the load fluctuation amount, information related to the corresponding peak value, information related to the air-fuel ratio correction amount immediately before the load change, and the injection ratio, the next fuel injection is performed. An injection ratio is determined. Here, the port adhesion amount of the port injection fuel injected from the port injection valve tends to increase as the alcohol concentration increases. For this reason, the peak value generated during the transient operation tends to increase as the alcohol concentration of the port-injected fuel increases. Further, the air-fuel ratio correction amount of the internal combustion engine tends to increase as fuel with a high alcohol concentration is injected. For this reason, the air-fuel ratio correction amount during steady operation tends to increase as the alcohol concentration of the fuel increases. That is, according to the present invention, information related to the alcohol concentration of the port-injected fuel and the in-cylinder-injected fuel can be obtained by using the relationship of the above information. Therefore, according to the present invention, it is possible to effectively suppress the deterioration of emission and the deterioration of drivability by changing the next injection ratio based on the information.

According to the second aspect of the invention, the port changes to the combustion state specified by the load fluctuation amount, information related to the corresponding peak value, information related to the air-fuel ratio correction amount immediately before the load fluctuation, and the injection ratio. Determination models in which the alcohol concentrations of the injected fuel and the in-cylinder injected fuel are associated with each other are prepared in advance. Then, the actually obtained load fluctuation amount, the corresponding transient A / F information, the steady A / F information, and the injection ratio are applied to the determination model. Therefore, according to the present invention, it is possible to accurately determine the alcohol concentration of the port injected fuel and the in-cylinder injected fuel, and therefore, by using the determined concentration information, it is possible to effectively reduce the emission and the drivability. It is possible to specify the injection ratio that can be suppressed.

According to the third invention, when the load change amount, the steady A / F information, and the injection ratio at that time are applied to the determination model, the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are equal. Transient A / F information (transient A / F reference information) is specified. Then, by applying the load change amount, transient A / F reference information, steady A / F information, and the alcohol concentration of the port injection fuel and in-cylinder injection fuel at that time to the determination model, The injection ratio is specified. Therefore, according to the present invention, even when the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are different, the combustion state equivalent to the combustion state when the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are equal. Therefore, it is possible to effectively determine the deterioration of emission and the deterioration of drivability.

According to the fourth aspect of the present invention, the peak value in the temporary fluctuation of the air-fuel ratio that occurs at the time when the load changes and the peak value under the same condition when using gasoline fuel (E0) with an alcohol concentration of 0% The difference amount is acquired as transient A / F information. It is difficult to superimpose the influence of the engine characteristic on the difference value of the peak value based on E0. For this reason, according to the present invention, a common determination model can be used in a wide range of engine configurations.

According to the fifth aspect of the present invention, the difference between the air-fuel ratio correction amount in the steady state immediately before the load changes and the air-fuel ratio correction amount under the same condition when using gasoline fuel (E0) with an alcohol concentration of 0%. Is acquired as steady A / F information. It is difficult to superimpose the influence of engine characteristics on the difference amount of the air-fuel ratio correction amount based on E0. For this reason, according to the present invention, a common model can be used in a wide range of engine configurations.

According to the sixth aspect of the invention, the load fluctuation amount, information related to the corresponding peak value (transient A / F information), and information related to the air-fuel ratio correction amount immediately before the load fluctuation (steady A / F information) Based on the injection ratio, it is determined whether or not a failure has occurred in the port injection valve or the in-cylinder injection valve. By using the relationship of the above information, information related to the alcohol concentration of the port injection fuel and the in-cylinder injection fuel can be obtained. When this information indicates an abnormal value, it is considered that fuel is not correctly injected due to a failure of the port injection valve or the in-cylinder injection valve. Therefore, according to the present invention, it is possible to accurately determine whether or not a failure of the port injection valve or the in-cylinder injection valve has occurred by using the above information.

According to the seventh aspect, when the ratio of the transient A / F information to the steady A / F information is larger than the predetermined upper limit value, it is determined that a clogging failure of the in-cylinder injection valve has occurred. When the ratio of the transient A / F information to the steady A / F information is large, it is presumed that the alcohol concentration of the port-injected fuel is higher than that of the in-cylinder-injected fuel. If it exceeds the maximum value, it can be inferred that the amount of in-cylinder injected fuel is abnormally reduced. For this reason, according to this invention, generation | occurrence | production of the clogging failure of a cylinder injection valve can be determined with sufficient precision.

According to the eighth aspect, when the ratio of the transient A / F information to the steady A / F information is smaller than the predetermined lower limit value, it is determined that a port injection valve clogging failure has occurred. When the ratio of the transient A / F information to the steady A / F information is small, it is presumed that the alcohol concentration of the port injection fuel is lower than that of the in-cylinder injection fuel. If it is too small, it can be inferred that the injection amount of the port injection fuel is abnormally reduced. For this reason, according to this invention, generation | occurrence | production of the clogging failure of a port injection valve can be determined accurately.

1 is a diagram showing a schematic configuration of an internal combustion engine to which a control device as Embodiment 1 of the present invention is applied. It is a figure for demonstrating the relationship between the alcohol concentration of a fuel, and the A / F correction amount at the time of steady operation. It is a figure which shows the behavior of the exhaust air fuel ratio which arises with the change of the opening degree of a throttle when the injection ratio of port injection and in-cylinder injection is made constant. It is an example of the map which prescribed | regulated the relationship between the steady A / F deviation | shift amount and transient A / F deviation | shift amount, and the alcohol concentration of the fuel currently used with an engine in a predetermined injection ratio and load change. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is an example of the map which prescribed | regulated the relationship between the steady A / F deviation | shift amount and transient A / F deviation | shift amount, and the alcohol concentration of the fuel currently used with an engine in a predetermined injection ratio and load change. It is a flowchart of the routine performed in Embodiment 2 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted. The present invention is not limited to the following embodiments.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine (hereinafter simply referred to as an engine) to which a control device as Embodiment 1 of the present invention is applied. The engine shown in FIG. 1 is a spark ignition type 4-stroke reciprocating engine. The engine includes a cylinder block 6 in which a piston 8 is disposed, and a cylinder head 4 assembled to the cylinder block 6. A space from the upper surface of the piston 8 to the cylinder head 4 forms a combustion chamber 10, and an intake port 18 and an exhaust port 20 are formed in the cylinder head 4 so as to communicate with the combustion chamber 10. An intake valve 12 for controlling the communication state between the intake port 18 and the combustion chamber 10 is provided at a connection portion between the intake port 18 and the combustion chamber 10, and an exhaust gas is provided at a connection portion between the exhaust port 20 and the combustion chamber 10. An exhaust valve 14 for controlling the communication state between the port 20 and the combustion chamber 10 is provided. A spark plug 16 is attached to the cylinder head 4 so as to protrude from the top of the combustion chamber 10 into the combustion chamber 10.

An intake passage 30 for introducing air into the combustion chamber 10 is connected to the intake port 18 of the cylinder head 4. An air cleaner 32 is provided at the upstream end of the intake passage 30, and air is taken into the intake passage 30 via the air cleaner 32. An air flow meter 56 that outputs a signal corresponding to the intake amount of air is disposed downstream of the air cleaner 32. The downstream portion of the intake passage 30 branches for each cylinder (for each intake port 18), and a surge tank 34 is provided at the branch point. A throttle 36 is disposed upstream of the surge tank 34 in the intake passage 30. The throttle 36 is provided with a throttle sensor 54 that outputs a signal corresponding to its opening.

Further, the exhaust port 20 of the cylinder head 4 is connected to an exhaust passage 40 for discharging combustion gas generated by combustion in the combustion chamber 10 as exhaust gas. A catalyst 42 for purifying exhaust gas is provided in the exhaust passage 40. An air-fuel ratio sensor 58 that outputs a signal corresponding to the air-fuel ratio of the exhaust gas is disposed upstream of the catalyst 42 in the exhaust passage 40.

The engine of this embodiment is configured as a dual injection system having two

injection valves

38 and 70 for each cylinder. One injection valve 38 is a port injection valve provided in the vicinity of the intake port 18 in the intake passage 30, and injects fuel into the intake port 18. The other injection valve 70 is an in-cylinder injection valve provided so as to face the inside of the combustion chamber 10 to the cylinder head 4, and directly injects fuel into the combustion chamber 10. In such a dual injection system, the injection ratio between the fuel injection amount from the port injection valve 38 (port injection amount) and the fuel injection amount from the in-cylinder injection valve 70 (in-cylinder injection amount) is arbitrarily set. Can do. In addition, since the engine of this Embodiment can use alcohol mixed fuel, the fuel injected from each

injection valve

38 and 70 is not restricted to gasoline, Alcohol mixed gasoline and 100% alcohol are injected. Sometimes.

The engine of this embodiment includes an ECU (Electronic Control Unit) 50 as a control device. To the output side of the ECU 50, various actuators such as the port injection valve 38, the in-cylinder injection valve 70, the throttle 36, and the spark plug 16 are connected. Various sensors such as a crank angle sensor 52 that outputs a signal corresponding to the rotation angle of the crankshaft 24 are connected to the input side of the ECU 50 in addition to the air flow meter 56, the throttle sensor 54, and the air-fuel ratio sensor 58 described above. ing. The ECU 50 operates each actuator provided in the engine according to a predetermined control program based on the output of each sensor provided in the engine.

[Operation of Embodiment 1]
Next, the operation of the control device according to the first embodiment will be described with reference to FIGS. In the engine of the present embodiment, feedback control of the air / fuel ratio is performed using the detection signal of the air / fuel ratio sensor 58. Specifically, the fuel injection amount is increased or decreased so that the air-fuel ratio of the exhaust gas detected by the air-fuel ratio sensor 58 becomes the target air-fuel ratio (for example, the theoretical air-fuel ratio).

Here, as described above, the engine of the present embodiment is an engine that can use alcohol mixed fuel. Therefore, the fuel injected from each of the

injection valves

38 and 70 is not limited to gasoline, but alcohol mixed gasoline or 100% Alcohol may be injected. However, since a fuel tank (not shown) is common between the

injection valves

38 and 70, the fuel injected from the two

injection valves

38 and 70 is usually the same type, and fuels with different alcohol concentrations are injected separately. There is no. Therefore, even when alcohol mixed fuel is used, the air-fuel ratio of the exhaust gas can be controlled to the target air-fuel ratio by performing the above-described air-fuel ratio control.

However, there is an exceptional case in which different types of fuel are injected from the two

injection valves

38 and 70. For example, immediately after refueling a fuel having a different alcohol concentration from the fuel currently used. This is because immediately after refueling, a new concentration of fuel reaches the

injection valves

38 and 70 via the fuel pipe, but this arrival timing is not always the same. This is because the pipe lengths from the fuel tank to the

injection valves

38 and 70 are different, and the fuel injection amounts from the

injection valves

38 and 70 are different. Therefore, during the period in which the fuel of different concentrations supplied reaches only one of the

injectors

38 and 70, the fuel injected from the two

injectors

38 and 70 has different concentrations, and the alcohol concentration Different fuels will be sprayed. In this case, in the above-described air-fuel ratio control, it takes time until the air-fuel ratio of the exhaust gas converges to the target air-fuel ratio, and there is a concern that emission and drivability deteriorate during this time.

Therefore, the engine of the present embodiment is characterized in that the alcohol concentration of the fuel injected from the two

injectors

38 and 70 is determined, respectively, and the fuel injection amount of each

injector

38 and 70 is controlled to an appropriate amount. Have. Hereinafter, the alcohol concentration determination method performed by the ECU 50 and the appropriate control of the fuel injection amount using the determined alcohol concentration will be described in detail.

FIG. 2 is a diagram for explaining the relationship between the alcohol concentration of fuel and the air-fuel ratio (A / F) correction amount during steady operation. In this figure, the alcohol concentration represents the fuel alcohol concentration in the combustion chamber 10, and the A / F correction amount represents the feedback correction amount (fuel amount) in the air-fuel ratio control during steady operation. Further, during steady operation here, the amount of fuel adhering to the intake port 18 is in a stable parallel state, and the air-fuel ratio of the exhaust gas is controlled to the target air-fuel ratio by air-fuel ratio control. Show.

As shown in this figure, the amount of deviation of the A / F correction amount from the E0 reference value when the gasoline fuel (E0) with 0% alcohol is used as the E0 reference value during steady operation. Is defined as the steady A / F deviation amount, it can be seen that the steady A / F deviation amount increases as the alcohol concentration increases. This is because the calorific value per unit volume of alcohol is smaller than that of gasoline fuel, so in order to generate the same torque as when gasoline fuel is used using alcohol fuel, the fuel injection amount must be increased. Depending on what you need to do. This indicates that the steady A / F deviation amount has a certain relationship with the fuel alcohol concentration in the combustion chamber 10, that is, the alcohol concentration of the cylinder injection fuel, the alcohol concentration of the port injection fuel, and the injection ratio. I mean.

FIG. 3 is a diagram showing the behavior of the exhaust air-fuel ratio that occurs with a change in the opening of the throttle 36 when the injection ratio of port injection and in-cylinder injection is constant. From this figure, when the throttle 36 is operated to the open side, the exhaust air-fuel ratio temporarily shifts to the lean side, and conversely, when the throttle 36 is operated to the close side, the exhaust air-fuel ratio temporarily shifts to the rich side. I understand that. The temporary fluctuation of the exhaust air-fuel ratio during such transient operation is caused by the fuel injected from the port injection valve 38 once adhering to the intake port 18, and the adhering fuel is vaporized and sucked into the combustion chamber 10. This takes a considerable amount of time.

For example, when the throttle 36 is opened, the fuel injection amount from each

injection valve

38, 70 is increased in accordance with the increase in engine load. At this time, a part of the fuel injected from the port injection valve 38 to the intake port 18 is sucked into the combustion chamber 10 together with the air in the intake port 18, but most of it is temporarily attached to the intake port 18. . For this reason, the amount of fuel sucked into the combustion chamber 10 from the intake port 18 increases with a delay in the amount of air, and the air-fuel ratio of the air-fuel mixture in the combustion chamber 10, that is, the exhaust air-fuel ratio is temporarily lean. It will shift to. On the other hand, when the throttle 36 is closed, the fuel injection amount from each of the

injection valves

38 and 70 is reduced in accordance with the decrease in the engine load, but the fuel amount sucked into the combustion chamber 10 is delayed with respect to the air amount. As a result, the exhaust air-fuel ratio temporarily shifts to the rich side.

Here, attention is paid to the magnitude of the temporary fluctuation of the exhaust air-fuel ratio that occurs as the throttle 36 is operated. There are the following three factors that determine the magnitude of the fluctuation of the exhaust air-fuel ratio, that is, the peak value of the fluctuation (indicated by an arrow in the figure). The first factor is the amount of change in engine load. Since the fuel injection amount is increased / decreased in accordance with a change in the engine load, the increase / decrease amount of the fuel injection amount increases with a large change in the engine load.

The second factor is the injection ratio between port injection and in-cylinder injection. If the total fuel injection amount is the same, the amount of fuel adhering to the intake port 18 is determined by the injection ratio of port injection and in-cylinder injection. As the ratio of the fuel amount adhering to the port to the required fuel amount (the fuel amount determined from the target air-fuel ratio and the in-cylinder intake air amount) increases, the delay of the fuel amount sucked into the combustion chamber 10 with respect to the air amount becomes more significant. Become. Therefore, when the engine load is increased and the total fuel injection amount is increased, the larger the ratio of the port-attached fuel amount to the required fuel amount, that is, the higher the port injection ratio in the injection ratio, the shorter the fuel amount. Becomes prominent, and the peak value of the deviation of the exhaust air-fuel ratio toward the lean side increases. Conversely, when the engine load is reduced and the total fuel injection amount is reduced, the larger the ratio of the port-attached fuel amount to the required fuel amount, that is, the higher the port injection ratio in the injection ratio, the more the fuel amount. Excessiveness becomes remarkable, and the peak value of the deviation of the exhaust air-fuel ratio to the rich side becomes large.

The third factor is the alcohol concentration of the port injection fuel injected from the port injection valve 38. The higher the alcohol concentration of the fuel, the harder the fuel adhering to the intake port 18 is vaporized, and the longer the response delay from when the fuel injection amount of the port injection valve 38 is changed until the change in the fuel amount flowing into the combustion chamber 10 appears. . For this reason, when the engine load increases, the higher the alcohol concentration of the fuel, the more the temporary shortage of the in-cylinder fuel amount with respect to the in-cylinder air amount becomes more prominent, and the peak value of the deviation of the exhaust air-fuel ratio to the lean side Becomes bigger. Further, when the engine load decreases, the higher the fuel alcohol concentration, the more the temporary excess of the fuel amount with respect to the intake air amount becomes more prominent, and the peak value of the deviation of the exhaust air / fuel ratio to the rich side becomes larger. If the peak value of fluctuation when using gasoline fuel (E0) with 0% alcohol is defined as the E0 reference value, and the shift amount of the peak value from the E0 reference value is defined as the transient A / F shift amount, the transient A / F Similar to the peak value, the amount of / F deviation increases as the fuel alcohol concentration increases.

The peak value of the fluctuation of the exhaust air / fuel ratio is determined by the above three factors. This means that there is a certain relationship among the transient A / F deviation amount, the engine load change amount, the injection ratio, and the fuel alcohol concentration of the port injection fuel.

Thus, the steady A / F deviation amount and the transient A / F deviation amount have a certain relationship with the alcohol concentration of the fuel used. These relationships will be described in more detail below. First, for example, consider a case where the alcohol concentration of the port-injected fuel changes due to fuel having a different alcohol concentration from the currently used fuel. As described above, the steady A / F deviation amount depends on the alcohol concentration of the port injected fuel and the alcohol concentration of the in-cylinder injected fuel. For this reason, the steady A / F deviation amount when the injection ratio is constant changes according to the change in the alcohol concentration of the port-injected fuel, but the degree of change is somewhat limited. On the other hand, the transient A / F deviation amount is dominated by the alcohol concentration of the port injection fuel and hardly depends on the alcohol concentration of the in-cylinder injection fuel. For this reason, when the alcohol concentration of the port-injected fuel changes, the transient A / F deviation amount is greatly affected and changes. That is, as the alcohol concentration of the port injection fuel is higher than that of the in-cylinder injection fuel, the transient A / F deviation amount becomes relatively larger than the steady A / F deviation amount. As the concentration is lower than the alcohol concentration of the in-cylinder injected fuel, it tends to be relatively small with respect to the steady A / F deviation amount.

Therefore, if this fixed relationship is modeled by a function, a map, or the like, the amount of change in engine load, the amount of transient A / F deviation, the amount of steady A / F deviation, and the injection ratio at that time are respectively shown. By specifying, it is possible to determine the alcohol concentration of the currently used fuel. FIG. 4 is an example of a map that defines the relationship between the steady A / F deviation amount and the transient A / F deviation amount and the alcohol concentration of the fuel currently used in the engine at a predetermined injection ratio and load change. It is. In the map shown in this figure, the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are respectively associated with the operating points on the map specified by the steady A / F deviation amount and the transient A / F deviation amount. Specifically, in this map, as the ratio of the transient A / F deviation amount to the steady A / F deviation amount is larger, the alcohol concentration of the port injection fuel becomes higher than that of the in-cylinder injection fuel. As the ratio of the transient A / F deviation amount to the / F deviation amount is smaller, the alcohol concentration of the port injection fuel is related to be lower than that of the in-cylinder injection fuel. Therefore, by storing a map as shown in FIG. 4 for each engine load change amount and each injection ratio, it is possible to accurately determine the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel, respectively. Become.

Next, the proper control of the fuel injection amount using the determined alcohol concentration will be described. According to the method described above, it is possible to accurately determine the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel. As a result, when the determined alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are different, it takes time until the air-fuel ratio of the exhaust gas converges to the target air-fuel ratio in the air-fuel ratio control described above. However, there is concern about the worsening of emissions and drivability during this period.

Here, under the condition where the alcohol concentration of the port injection fuel and the in-cylinder injection fuel are equal, good combustion is realized by the air-fuel ratio control. Therefore, in the engine of the present embodiment, when the determined alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are different, the combustion is performed when the alcohol concentrations of these injected fuels are equal by changing to the injection ratio. A condition equivalent to the condition is formed.

If the injection ratio is changed, the steady A / F deviation does not change greatly, but the transient A / F deviation changes according to the injection ratio. More specifically, if the various conditions (port injection fuel alcohol concentration, in-cylinder fuel alcohol concentration, engine load change amount) are set to the same conditions, and the injection ratio is changed, the current fuel alcohol concentration is activated. The point (white circle in FIG. 4) changes while keeping the steady A / F deviation amount substantially constant. Therefore, a plurality of injection ratios for the current operating point of fuel alcohol concentration (white circle in FIG. 4) to become the operating point (black circle in FIG. 4) at which the alcohol concentration of the port-injected fuel and in-cylinder injected fuel are equal. By specifying from these maps, it is possible to form combustion conditions equivalent to the case where the fuel alcohol concentrations of these injection valves are equal.

[Specific Processing in Embodiment 1]
Next, with reference to FIG. 5, the specific content of the process performed in this Embodiment is demonstrated. FIG. 5 is a flowchart of a routine executed by the ECU 50. Note that the routine shown in FIG. 5 may be repeatedly executed while the engine is in operation, or a predetermined period after refueling or when there is a difference in alcohol concentration between the port injection fuel and the cylinder injection fuel. It may be executed only during a certain period.

In the routine shown in FIG. 5, the currently set injection ratio of port injection and in-cylinder injection is acquired (step 100).

Next, when a change in engine load is detected, the amount of change is acquired (step 102). Specifically, the ECU 50 calculates the engine load from the opening of the throttle 36, the engine speed, the output value of the air flow meter 56, and the like. The amount of change in engine load acquired is the amount of change in engine load per unit time (Δengine load / sec).

Next, it is determined whether or not the engine load change amount is smaller than a predetermined value (step 104). As a result, when | Δengine load / sec | <predetermined value is established, it is determined that the engine is in steady operation. In this case, the process proceeds to the next step, and the steady A / F deviation amount is detected (step 106). Here, specifically, the current A / F correction amount in the air-fuel ratio control and the A / F correction amount under the same condition when using gasoline fuel (E0) with 0% alcohol (reference A / F correction) Amount) is acquired. Then, a value obtained by subtracting the reference A / F correction amount from the current A / F correction amount is calculated as the steady A / F deviation amount. When the process of step 106 is executed, the process returns to step 100 described above. That is, during the steady operation of the engine, the processing of steps 100 to 106 is repeatedly executed.

On the other hand, in step 104, if | Δengine load / sec | <predetermined value is not established, it is determined that the engine is in a transient operation. In this case, the process proceeds to the next step, and a transient A / F deviation amount is detected (step 108). Here, specifically, the peak value of the fluctuation of the exhaust air / fuel ratio caused by the change of the engine load and the peak value under the same condition when using gasoline fuel (E0) with 0% alcohol (reference peak) Value). Then, a value obtained by subtracting the reference peak value from the current peak value is calculated as the transient A / F deviation amount.

Next, the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are determined (step 110). Here, specifically, it corresponds to the injection ratio acquired in step 100 from the map group constituting the determination model of the fuel alcohol concentration and the engine load change amount during transient operation acquired in step 102. A map (map as shown in FIG. 4) is selected. Then, the steady A / F deviation amount acquired in step 106 and the transient A / F deviation amount acquired in step 108 are applied to the selected map. Thereby, the alcohol concentration of the in-cylinder injected fuel and the port injected fuel currently used in the engine is accurately determined.

Next, in the in-cylinder injected fuel and the port-injected fuel, the injection ratio is specified so that the in-cylinder combustion conditions are equivalent to those in the case where the fuel alcohol concentrations are equal ( Step 112). If the injection division ratio is changed, the steady A / F deviation amount does not change greatly, but the transient A / F deviation amount changes according to the injection division ratio. Therefore, specifically, here, the operating point of the current fuel alcohol concentration (white circle in FIG. 4) is the operating point (black circle in FIG. 4) at which the alcohol concentrations of the cylinder injection fuel and the port injection fuel are equal. The map at the position is selected, and the injection ratio associated with the map is specified. Next, the injection ratio currently used in the engine is changed to the injection ratio acquired in step 112 (step 114).

As described above, according to the engine of the present embodiment, the in-cylinder injection fuel and the port injection fuel that are currently used are utilized by utilizing the relationship between the steady A / F deviation amount and the transient A / F deviation amount. The alcohol concentration can be accurately determined. Further, according to the engine of the present embodiment, even if the alcohol concentrations of the in-cylinder injected fuel and the port injected fuel are different by changing the injection ratio, these fuel alcohol concentrations It is possible to form a combustion condition equivalent to the case where is equal. As a result, a situation in which the exhaust air-fuel ratio becomes rough can be suppressed, so that it is possible to effectively suppress the deterioration of emission and the deterioration of drivability.

In the first embodiment described above, the steady A / F deviation amount and the transient A / F deviation amount based on the case where gasoline fuel (E0) that is 0% alcohol is used are used. The A / F correction amount and A / F fluctuation peak value during operation may be used as they are. However, the steady A / F deviation amount and the transient A / F deviation amount are based on the case where gasoline fuel (E0) is used, so a common model should be used even if the engine characteristics are different. It is effective in that

In the first embodiment described above, the alcohol concentration of the port-injected fuel and the in-cylinder-injected fuel is determined using the amount of change in engine load, steady A / F deviation, transient A / F deviation, and injection ratio. Is determined from the map, and the injection ratio is specified from the map using the determined alcohol concentration. However, the injection ratio need not necessarily be specified by a map. For example, the optimum fuel injection ratio may be specified by estimating the fuel adhesion amount from the determined alcohol concentration and the operating conditions. Moreover, it is not always necessary to determine the values of the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel. For example, information on the combustion state caused by the alcohol concentration of the port injection fuel and the in-cylinder injection fuel is obtained from the map. After the determination, the injection ratio may be specified using such information.

In the first embodiment described above, the transient A / F deviation amount is the “transient A / F information” in the first invention, and the steady A / F deviation amount is the “steady A / F deviation” in the first invention. "F information" respectively. In the first embodiment described above, the ECU 50 executes the process of step 100, so that the “injection ratio acquisition means” in the first aspect of the invention executes the process of step 102. The “load change amount acquisition means” in the first invention executes the process in step 106, so that the “steady A / F information acquisition means” in the first invention performs the process in step 108. By executing, the “transient A / F information acquisition means” in the first invention realizes the “changing means” in the first invention by executing the processing of step 114 above. .

Further, in the first embodiment described above, the ECU 50 executes the process of step 110, so that the “first means” in the second aspect of the invention executes the process of step 112. Each of the “second means” in the second invention is realized.

Embodiment 2. FIG.
[Features of Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIG. 6 and FIG. The second embodiment can be realized by executing a routine shown in FIG. 7 to be described later using the system shown in FIG.

In the first embodiment described above, the alcohol concentration of the port-injected fuel and the in-cylinder-injected fuel is mapped using the change amount of the engine load, the steady A / F deviation amount, the transient A / F deviation amount, and the injection ratio. It is decided to judge from. Here, as described above, in this map, the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are associated with the operating points on the map specified by the steady A / F deviation amount and the transient A / F deviation amount, respectively. It has been. In this map, as the ratio of the transient A / F deviation amount to the steady A / F deviation amount is larger, the alcohol concentration of the port injection fuel becomes higher than that of the in-cylinder injection fuel. As the ratio of the transient A / F deviation amount to the / F deviation amount is smaller, the alcohol concentration of the port injection fuel is related to be lower than that of the in-cylinder injection fuel.

However, there are areas that are not actually assumed in this map. FIG. 6 is an example of a map that defines the relationship between the steady A / F deviation amount and the transient A / F deviation amount and the alcohol concentration of the fuel currently used in the engine at a predetermined injection ratio and load change. is there. The A region in this map is a region that belongs when the steady A / F displacement amount corresponding to the transient A / F displacement amount is unexpectedly small, and belongs to the region in the normal control range. Absent. Therefore, when the current operating condition belongs to the A region, it can be determined that the in-cylinder injected fuel has not reached the required amount, that is, the in-cylinder injection valve 70 is clogged.

Further, the region B in the figure is a region that belongs when the transient A / F shift amount corresponding to the steady A / F shift amount is unexpectedly small, and belongs to the region in the normal control range. There is no. Therefore, when the current operating condition belongs to the B region, it can be determined that the port injection fuel has not reached the required amount, that is, the port injection valve 38 is clogged.

Therefore, by determining whether or not the current operating condition belongs to the A region or the B region, it is possible to accurately determine whether or not the in-cylinder injection valve 70 or the port injection valve 38 is clogged. .

[Specific Processing in Second Embodiment]
Next, with reference to FIG. 7, the specific content of the process performed in this Embodiment is demonstrated. FIG. 7 is a flowchart of a routine in which the ECU 50 determines whether or not a clogging abnormality has occurred in the port injection valve 38 and the in-cylinder injection valve 70. Note that the routine shown in FIG. 7 is repeatedly executed during operation of the engine.

In the routine shown in FIG. 7, the currently set injection ratio of port injection and in-cylinder injection is acquired (step 200). Next, when a change in engine load is detected, the amount of change is acquired (step 202). Next, it is determined whether or not the change amount of the engine load is smaller than a predetermined value (step 204). As a result, when it is recognized that | Δengine load / sec | <predetermined value is established, the steady A / F deviation amount is detected (step 206). On the other hand, in the above step 204, when | Δengine load / sec | <predetermined value is not established, a transient A / F deviation amount is detected (step 208). In steps 200 to 208, specifically, the same processing as the processing in steps 100 to 108 is executed.

Next, it is determined whether or not the operating point on the map belongs to a predetermined area A (step 210). Specifically, the map corresponding to the injection ratio acquired in step 200 and the change amount of the engine load during the transient operation acquired in step 202 from the map group constituting the determination model (FIG. 6). Is selected). Then, the steady A / F deviation amount acquired in step 206 and the transient A / F deviation amount acquired in step 208 are applied to the selected map. Then, it is determined whether or not the applied operating point on the map belongs to the A region. The A area is stored in advance on the map as an area where the steady A / F deviation amount corresponding to the transient A / F deviation amount is unexpectedly small. As a result, when it is determined that the operating point on the map belongs to the A region, it is determined that the injection amount from the in-cylinder injection valve 70 is decreased, and the process proceeds to the next step, and the in-cylinder injection is performed. It is determined that there is a clogging abnormality of the valve 70 (step 212).

On the other hand, if it is determined in step 210 that the operating point on the map does not belong to the area A, the process proceeds to the next step, and whether or not the operating point on the map belongs to the predetermined area B is determined. A determination is made (step 214). Specifically, the operating point on the map is applied by the same processing as in step 210, and it is determined whether or not this operating point belongs to the B region. The B area is stored in advance on the map as an area where the transient A / F deviation amount corresponding to the steady A / F deviation amount is unexpectedly small. As a result, when it is determined that the operating point on the map belongs to the region B, it is determined that the injection amount from the port injection valve 38 has decreased, the process proceeds to the next step, and the port injection valve 38 It is determined that there is a clogging abnormality (step 216).

On the other hand, if it is determined in step 214 that the operating point on the map does not belong to the B region, it is determined that there is no clogging abnormality in the port injection valve 38 and the in-cylinder injection valve 70, and the next step Then, it is determined that these injection valves are normal (step 218).

As described above, according to the engine of the present embodiment, the port injection valve 38 and the in-cylinder injection valve that are currently used by utilizing the relationship between the steady A / F deviation amount and the transient A / F deviation amount. The presence / absence of abnormality due to clogging of 70 can be accurately determined.

By the way, in Embodiment 2 described above, the steady A / F deviation amount and the transient A / F deviation amount based on the case where gasoline fuel (E0) that is 0% alcohol is used are used. The A / F correction amount and A / F fluctuation peak value during operation may be used as they are. However, the steady A / F deviation amount and the transient A / F deviation amount are based on the case where gasoline fuel (E0) is used, so a common model should be used even if the engine characteristics are different. It is effective in that

In the second embodiment described above, only the determination of the presence / absence of a failure due to clogging of the port injection valve 38 and the in-cylinder injection valve 70 is executed, but the determination of alcohol concentration and the injection in the first embodiment described above are performed. The dividing ratio changing operation may be executed together with the above-described failure presence / absence determining operation.

In the second embodiment described above, the transient A / F deviation amount is “transient A / F information” in the first invention, and the steady A / F deviation amount is “steady A / F information” in the first invention. "F information" respectively. In the second embodiment described above, the ECU 50 executes the process of step 200, so that the “injection ratio acquisition unit” in the first aspect of the invention executes the process of step 202. The “load change amount acquisition means” in the first invention executes the process in step 206, so that the “steady A / F information acquisition means” in the first invention performs the process in step 208. By executing, the “transient A / F information acquisition means” in the first invention is realized.

In the second embodiment described above, the ECU 50 executes the process of step 210, and the “determination means” in the sixth or seventh invention executes the process of step 214. The “determination means” in the sixth or eighth invention is realized.

10 Combustion chamber 36 Throttle 18 Intake port 38 Port injection valve 50 ECU (Electronic Control Unit)
58 Air-fuel ratio sensor 70 In-cylinder injection valve

Claims

A port injection valve for injecting fuel into the intake port; and an in-cylinder injection valve for injecting fuel into the cylinder; and the port injection valve and the cylinder in the cylinder so that the exhaust air-fuel ratio of the internal combustion engine becomes a target air-fuel ratio A control device for an internal combustion engine that performs air-fuel ratio control for controlling a fuel injection amount injected from an injection valve,
Means for obtaining an injection ratio between a fuel injection amount from the port injection valve and a fuel injection amount from the in-cylinder injection valve;
Means for acquiring a change amount of the load when the load of the internal combustion engine changes;
Transient A / F information acquisition means for detecting a temporary fluctuation of the exhaust air-fuel ratio that occurs when the load of the internal combustion engine changes, and acquiring information related to the peak value as transient A / F information;
Steady A / F information means for obtaining information related to the correction amount of the air-fuel ratio immediately before the load of the internal combustion engine changes as steady A / F information;
Change means for changing the injection ratio at the next fuel injection based on the load change amount, the corresponding transient A / F information, the steady A / F information, and the injection ratio at that time;
A control device for an internal combustion engine, comprising:
The changing means is
The amount of change in load, transient A / F information, steady A / F information, and injection ratio of port injection fuel injected from the port injection valve and in-cylinder injection fuel injected from the in-cylinder injection valve A decision model that correlates alcohol concentration;
By applying the change amount of the load, the corresponding transient A / F information, the steady A / F information, and the injection ratio at that time to the determination model, the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are respectively determined. A first means for determining;
A second means for specifying an injection ratio at the next fuel injection based on the alcohol concentration of the port injection fuel and the in-cylinder injection fuel;
The control apparatus for an internal combustion engine according to claim 1, comprising:
The second means applies the change amount of the load, the steady A / F information, and the injection ratio at that time to the determination model, so that the alcohol concentrations of the port injection fuel and the in-cylinder injection fuel are equal. The transient A / F information is specified as the transient A / F reference information, the load change amount, the transient A / F reference information, the steady A / F information, and the alcohol concentration of the port injection fuel and the in-cylinder injection fuel at that time 3. The control device for an internal combustion engine according to claim 2, wherein the injection ratio is determined at the next fuel injection by applying to the determination model.
The steady-state A / F information acquisition means acquires, as the transient A / F information, a difference amount between the peak value and a peak value under the same condition when using gasoline fuel having an alcohol concentration of 0%. 4. The control device for an internal combustion engine according to claim 2, wherein the control device is an internal combustion engine.
The steady-state A / F information acquisition means obtains the difference amount between the correction amount of the air-fuel ratio and the correction amount of the air-fuel ratio under the same condition when using gasoline fuel having an alcohol concentration of 0%. 5. The control device for an internal combustion engine according to claim 2, wherein the control device is acquired as / F information.
Determining means for determining an abnormality of the port injection valve or the in-cylinder injection valve based on a load change amount, transient A / F information corresponding thereto, steady A / F information, and an injection ratio at that time; The control device for an internal combustion engine according to any one of claims 1 to 5, further comprising:
When the ratio of the transient A / F information to the steady A / F information is greater than a predetermined upper limit value determined based on the load change amount and the injection ratio at that time, 7. The control apparatus for an internal combustion engine according to claim 6, wherein occurrence of clogging failure of the in-cylinder injection valve is determined.
When the ratio of the transient A / F information to the steady A / F information is smaller than a predetermined lower limit value determined based on the load change amount and the injection ratio at that time, 8. The control apparatus for an internal combustion engine according to claim 6, wherein occurrence of clogging failure of the port injection valve is determined.