JP2009144530A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow improvement of emission control efficiency of a catalyst while supplying secondary air to an exhaust passage. <P>SOLUTION: A control device 1 of an internal combustion engine comprises a first fuel injection means 11d capable of injecting a first predetermined quantity of fuel into a cylinder, a second fuel injection means 11p capable of injecting a second predetermined quantity of fuel into an intake passage, an exhaust emission control means provided in the exhaust passage and controlling emission of exhaust gas, an air supply means 29 capable of supplying secondary air to the exhaust passage, and a control means 30 controlling the first fuel injection means and the second fuel injection means to vary a first ratio of the first predetermined quantity to a total injection quantity summed up the first predetermined quantity and the second predetermined quantity and a second ratio of the second predetermined quantity to the total injection quantity and controlling the first fuel injection means and the second fuel injection means so that the first ratio in case of supplying the secondary air becomes larger in comparison with the first ratio in case of not supplying the secondary air. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technical field of a control device for an internal combustion engine that controls, for example, an internal combustion engine in which secondary air is supplied into an exhaust passage.

  As a control device for this type of internal combustion engine, in Patent Document 1 and the like, when an increase in the temperature of the exhaust gas is required, main injection is performed for the purpose of generating torque in the intake stroke or the compression stroke, A control device is disclosed in which secondary fuel injection is performed in the expansion stroke. In this control device, secondary air is further supplied into the exhaust passage by AI (Air Injection) means.

  On the other hand, a control device for an internal combustion engine that can be injected into the combustion chamber in addition to the intake passage, that is, both port injection and in-cylinder injection (or direct injection) are proposed.

JP 2000-80947 A JP 2003-056392 A Japanese Patent No. 3826642 JP 2005-307916 A

  However, according to Patent Document 1 and the like described above, in order to purify the catalyst more effectively by supplying the secondary air, it is necessary to increase the injection amount of the secondary fuel and the main injection fuel. This causes a technical problem that fuel consumption is reduced. In addition, when the fuel injection amount is increased, fuel injected locally or partially in the periphery of the spark plug is caused by the spray formation effect or the like in the recess in the upper part of the piston, so-called piston cavity. Therefore, there is a technical problem that there is a possibility of misfire due to the spark plug turning or the like.

  The present invention has been made in view of the above problems, for example, and provides a control device for an internal combustion engine capable of improving the purification efficiency of a catalyst while supplying secondary air to an exhaust passage. This is the issue.

  In order to solve the above problems, a control apparatus for an internal combustion engine according to the present invention includes a first fuel injection means (for example, a direct injection injector) capable of injecting a first predetermined amount of fuel into a cylinder of the internal combustion engine, and the internal combustion engine. Second fuel injection means (for example, a port injector) capable of injecting a second predetermined amount of fuel into the intake passage of the engine, and exhaust purification means (for example, a catalyst) provided in the exhaust passage of the internal combustion engine for purifying exhaust gas An air supply means capable of supplying secondary air to the exhaust passage, a first ratio of the first predetermined amount to a total injection amount that is the sum of the first predetermined amount and the second predetermined amount, and the total amount In addition to controlling at least one of the first fuel injection means and the second fuel injection means to change the second ratio of the second predetermined amount to the injection amount, the secondary To supply fresh air It said first ratio in a case, and a control means for controlling at least one of the injection means so as to be larger as compared with the first ratio in a case that does not supply the secondary air.

  According to the control apparatus for an internal combustion engine according to the present invention, in the internal combustion engine, fuel injection is performed by the first and second fuel injection means, for example, at an injection ratio of fuel according to an operation state. That is, a first predetermined amount of fuel is injected into the cylinder of the internal combustion engine by the first fuel injection means, and a second predetermined amount of fuel is injected into the intake passage of the internal combustion engine by the second fuel injection means.

  Further, secondary air is supplied to the exhaust passage by the air supply means. Here, “secondary air” according to the present invention means air mainly intended to be directly supplied to the exhaust system of the internal combustion engine, and is supplied to the intake system of the internal combustion engine. This is different from air whose main purpose is to be burned in the cylinders of the engine. Typically, this secondary air is supplied to the exhaust passage in order to raise the temperature of the exhaust purification means.

  During such normal operation of the internal combustion engine, under the control of the control means, the total injection quantity is the sum of the first predetermined quantity injected by the first fuel injection means and the second predetermined quantity injected by the second fuel injection means. The first ratio of the first predetermined amount changes. In addition to or instead of this, the second ratio of the second predetermined amount to the total injection amount is changed. Here, the “first ratio” according to the present invention means a ratio of the first predetermined amount to be injected by the first fuel injection means, such as a direct injection ratio described later, with respect to the total injection amount. The “second ratio” according to the present invention means, for example, a ratio of the second predetermined amount to be injected by the second fuel injection means such as a port injection ratio described later with respect to the total injection amount. If either one of the first ratio and the second ratio is determined, one of the first ratio and the second ratio may be determined by subtracting the determined one from 100%. Further, “%” relating to the ratio of fuel injected in the present application is a relative ratio of the first ratio and the second ratio, and basically means “weight%” throughout, but the same fuel. May be volume%, and may be dimensionless in the sense of the relative proportion between the injection means.

  In particular, under the control of the control means, at least one of the first fuel injection means and the second fuel injection means causes the air supply means to increase the temperature of the exhaust purification means so as to be secondary to the exhaust passage. The first predetermined amount and the second predetermined amount of fuel are injected so that the first ratio in the case of supplying air is larger than the first ratio in the case of not supplying secondary air. Here, “in the case where secondary air is supplied to the exhaust passage” according to the present invention, in addition to or in place of the presence or absence of secondary air supply, This means that the degree of secondary air supply is relatively high. In addition, “when secondary air is not supplied to the exhaust passage” according to the present invention means in addition to or instead of meaning that there is no supply among the presence or absence of secondary air supply, This means that the degree of secondary air supply is relatively low.

  Typically, for example, secondary air supply based not only on the presence / absence or degree of secondary air supply to the exhaust passage, but also on other parameters (eg engine speed, load, etc.) The first and second ratios may be changed for each position or region on the coordinate plane spanned by the presence / absence or degree of and other parameters. Therefore, the first ratio described above is typically based on the degree of cooling in which the cylinder is cooled by the fuel injected into the cylinder, in addition to the presence or absence or degree of secondary air supply, This is the ratio of the first predetermined amount to be injected by the prescribed first fuel injection means to the total injection amount. Alternatively, the second ratio described above typically means that the second fuel injection means defined based on the degree of cooling of the cylinder in addition to the presence or absence or degree of secondary air supply. This is the ratio of the second predetermined amount to be injected to the total injection amount.

  As a result, when the secondary air is supplied to the exhaust passage, the air is sucked into the cylinder of the internal combustion engine due to the first ratio increased compared to the case where the secondary air is not supplied. In the air-fuel mixture, the degree of local or partial fuel concentration (so-called rich state) is increased compared to the case where secondary air is not supplied. As a result, the CO or HC concentration in the exhaust gas when secondary air is supplied to the exhaust passage is increased as compared with the CO or HC concentration in the exhaust gas when secondary air is not supplied. . Accordingly, even if the air-fuel ratio of the exhaust gas when the secondary air is supplied to the exhaust passage is the same as the air-fuel ratio of the exhaust gas when the secondary air is not supplied, the exhaust system It is possible to further promote the chemical reaction in the interior of the catalyst and in the catalyst, speed up the temperature rise of the catalyst, activate the catalyst early, and purify the exhaust gas more appropriately.

  As a result, when secondary air is supplied to the exhaust passage, it is possible to effectively suppress the fuel injection from being significantly increased in order to improve the purification efficiency of the catalyst, and the exhaust gas It is possible to purify the gas more efficiently and more appropriately.

  In one aspect of the control apparatus for an internal combustion engine according to the present invention, the control means further injects fuel at a time when it approaches the top dead center of the compression stroke of the internal combustion engine when the secondary air is supplied. The first fuel injection is larger than the first predetermined amount that is injected at a time when the first predetermined amount is close to the top dead center of the compression stroke when the secondary air is not supplied. Control means.

  According to this aspect, when the secondary air is supplied to the exhaust passage, the combustion of the cylinder of the internal combustion engine is caused by the first predetermined amount of fuel injected at the time when the compression stroke approaches the top dead center. The degree to which a fuel concentration state (so-called rich state) is locally or partially formed in the vicinity of the spark plug in the room is greater than when secondary air is not supplied. Here, the “timing close to the top dead center of the compression stroke” according to the present invention means a timing included in the latter half of the compression stroke such as 270 degrees to 360 degrees in the crank angle, for example. Thereby, the chemical reaction in the exhaust system or in the catalyst can be further promoted, the exhaust gas purification action can be further promoted, and early activation of the catalyst can be realized.

  In another aspect of the control device for an internal combustion engine according to the present invention, when the control means supplies the secondary air, the control means further sets the first ratio of the fuel to be injected in the compression stroke of the internal combustion engine, The at least one injection unit is controlled to be larger than the second ratio in the intake stroke of the internal combustion engine.

  According to this aspect, in the case where secondary air is supplied to the exhaust passage, in the air-fuel mixture sucked into the cylinder of the internal combustion engine due to the first ratio larger than the second ratio, The degree of partial fuel concentration (so-called rich state) is greater than when the first ratio is less than the second ratio. Thereby, the chemical reaction in the exhaust system or in the catalyst can be further promoted, the exhaust gas purification action can be further promoted, and early activation of the catalyst can be realized.

  In another aspect of the control device for an internal combustion engine according to the present invention, the control means further includes at least one fuel of the first predetermined amount and the second predetermined amount when the secondary air is supplied. The at least one injection means is controlled so as to change the injection timing for injecting the fuel to the retard side compared to the injection timing for injecting the at least one fuel when the secondary air is not supplied. .

  According to this aspect, when the secondary air is supplied to the exhaust passage, the cylinder of the internal combustion engine is caused by the injection timing changed to the retard side compared to the case where the secondary air is not supplied. In the vicinity of the spark plug in the combustion chamber, the degree of local or partial fuel concentration (so-called rich state) is increased compared to the case where secondary air is not supplied. . As a result, stratified combustion is more effectively promoted, and fuel ignition is more reliably performed. Thereby, the chemical reaction in the exhaust system or in the catalyst can be further promoted, the exhaust gas purification action can be further promoted, and early activation of the catalyst can be realized.

  In another aspect of the control apparatus for an internal combustion engine according to the present invention, the first fuel injection means can further inject secondary fuel in an expansion stroke or an exhaust stroke of the internal combustion engine, and the control means includes: The injection timing of the secondary fuel when the secondary air is supplied is compared with the injection timing when the secondary air is not supplied from the expansion stroke to the exhaust stroke of the internal combustion engine. The first fuel injection means is controlled so as to approach the changing bottom dead center.

  According to this aspect, the injection timing of the secondary fuel when the secondary air is supplied under the control of the control means is compared with the injection timing when the secondary air is not supplied. The fuel is injected into the secondary fuel by the first fuel injection means while approaching the bottom dead center that changes from the expansion stroke to the exhaust stroke of the engine. Here, `` approaching the bottom dead center '' according to the present invention means that the fuel injected in the recess in the upper part of the piston, the so-called piston cavity, is locally or around the spark plug due to the spray formation effect or the like. This means the position of the piston that is determined according to a state in which the concentration of the fuel is partially high (so-called rich state) is hardly formed or the degree of formation is remarkably low.

  As a result, in the vicinity of the ignition plug in the combustion chamber of the cylinder of the internal combustion engine, a state in which the concentration of fuel not intended for combustion in the expansion stroke or the exhaust stroke is not formed (so-called rich state) is not formed or is formed. Is significantly reduced, so that the spark plug can be prevented from being blown (burring), and the spark plug is unintentionally conducting due to the crack in the spark. Can be prevented.

  As a result, when the secondary fuel is injected into the exhaust passage in the expansion stroke or the exhaust stroke, it is possible to prevent the secondary fuel from adversely affecting the spark plug. Appropriate combustion can be achieved.

  In particular, in addition to the injection of the first and second predetermined amounts of fuel and the supply of secondary air to the exhaust passage, the injection of the secondary fuel is temporarily performed in one cycle. In the case of injecting a certain amount of fuel, a fixed amount of fuel is injected into the intake stroke as compared to the concentrated injection in the intake stroke and compression stroke, which are the injection timings of the first and second predetermined amounts of fuel described above. It is possible to spray in a distributed manner over the compression stroke, the expansion stroke and the discharge stroke. As a result, the first predetermined amount to be injected into the cylinder of the internal combustion engine can fall within a range in which appropriate combustion can be realized in the cylinder. If a certain amount of fuel is injected into the cylinder intensively during the intake stroke or compression stroke, it may be too rich around the spark plug in the combustion chamber of the cylinder of the internal combustion engine, and combustion may not be performed properly. Will occur. In contrast, in the present invention, in addition to the above-described first and second predetermined amount of fuel injection and secondary air supply to the exhaust passage, secondary fuel injection is dispersed. As a result, proper combustion is achieved in the cylinder.

  In addition to this, the amount of secondary fuel injection can be determined appropriately and with high accuracy in accordance with the amount of secondary air supplied to the exhaust passage. It is possible to promote the chemical reaction in the catalyst more appropriately, further promote the exhaust gas purification action, and realize early activation of the catalyst.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  In the following embodiments, description will be given of a case where the control device for an internal combustion engine of the present invention is applied to a port and a direct injection engine.

(1) Basic Configuration First, the basic configuration of the port and the direct injection engine according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a block diagram conceptually showing the basic configuration of the port and the direct injection engine according to this embodiment, and FIG. 2 is a cross section of the port and the direct injection engine according to the present embodiment. FIG. 3 is a cross-sectional view conceptually showing a cross section of an injector included in a port and an in-cylinder injection engine according to the present embodiment.

  As shown in FIG. 1, a direct injection injector 11 d together with a spark plug 13 is provided for each cylinder in a port and a cylinder head portion of a cylinder 2 of the direct injection type engine 1 according to the present embodiment. A port injector 11p is provided in each intake passage communicating with each cylinder. In addition, the port and the direct injection type engine 1 according to the present embodiment include a supercharging pressure (that is, an intake pressure) in the intake system, in addition to an air-fuel ratio sensor that measures the air-fuel ratio in the intake system and the exhaust system (not shown). It is equipped with a supercharging pressure sensor that measures the atmospheric pressure.

  As shown in FIG. 2, the direct injection injector 11d is attached to the cylinder 2 at an angle, for example, and directly injects fuel into the cylinder 2 (that is, the combustion chamber). Further, for example, a cavity 6 is formed at the top of the piston 5 that reciprocates in the cylinder 2. The fuel injected from the direct injection injector 11d flows through the cylinder 2 as a swirl flow or a tumble flow through the cavity 6.

  Further, as shown in FIG. 3, the direct injection injector 11 d includes a swirl valve that injects fuel from the injection hole 113 after the swirl portion 112 forms a swirling flow. In this embodiment, a groove is provided in the needle 111 of the direct injection injector 11d, and a swirling flow is formed by the fuel flowing into the sac portion 112 through the groove.

  In FIG. 1 again, the direct injection injector 11d is supplied with fuel via the fuel supply unit 14. More specifically, the fuel supply unit 14 is connected to the fuel tank 16 while being connected to the direct injection injector 11 d via the fuel pipe 15. The fuel supply unit 14 includes, for example, a high pressure fuel pump (not shown), and high pressure fuel can be supplied to the injector 11d by the high pressure fuel pump. At this time, the fuel supply unit 14 includes a pressure regulating valve that regulates the fuel supplied from the high-pressure fuel pump to a desired pressure. The fuel whose pressure is adjusted in the pressure regulating valve is supplied to the direct injection injector 11d and then injected into the cylinder 2 with the pressure adjusted in the pressure regulating valve (or with the pressure adjusted according to the pressure adjusted in the pressure regulating valve). Is done.

  The fuel injection operation from the direct injection injector 11 is controlled by the operation of the ECU 30. Particularly, the direct injection injector is provided by the operation of the injection period setting unit 302 for setting the period during which the fuel is injected, the injection number setting unit 303 for setting the number of times the fuel is injected, the injection control unit 304, and the like. The fuel injection operation from 11 is controlled. The operation of the spark plug 13 is controlled by the operation of the ECU 30 (particularly, the operation of the ignition timing control unit 305 and the like provided in the ECU 30). The operation of the fuel supply unit 14 (that is, the pressure adjustment) is controlled by the operation of the ECU 30 (particularly, the operation of the fuel pressure setting unit 301 provided in the ECU 30).

  Then, the air taken into the combustion chamber 5 through the intake manifold 3 and the intake port 7 (see FIG. 2) and the fuel injected from the direct injection injector 11d and the port injector 11p are mixed in the combustion chamber 5. As the spark plug 13 sparks, the mixed gas burns in the combustion chamber 5. The exhaust gas after combustion is discharged to the outside of the port and the in-cylinder injection engine 1 through the exhaust port 8 (see FIG. 2) and the exhaust manifold 4.

  Under the present circumstances, the knocking sensor 12 is provided in the cylinder head part of the cylinder 2 of the cylinder injection type engine 1 which concerns on this embodiment for every cylinder. The knocking sensor 12 can detect the occurrence of knocking for each cylinder. When the occurrence of knocking is detected, a knocking detection signal indicating that the occurrence of knocking has been detected is output from the knocking sensor 12 to the ECU 30.

  Further, as shown in FIG. 1, the port and in-cylinder injection engine 1 includes an exhaust turbine 21, a compressor 22, a rotor shaft 23, an air cleaner 24, and an intercooler 25.

  In the exhaust system (that is, the exhaust passage) downstream from the cylinder of the internal combustion engine, secondary air is supplied by the air supply means 29.

  Exhaust gas discharged from the port and the cylinder 2 of the in-cylinder injection engine 1 is sprayed to the exhaust turbine 21 via the exhaust manifold 4. The exhaust turbine 21 is rotated by the exhaust gas. As the exhaust turbine 21 rotates, the compressor 22 connected to the exhaust turbine 21 via the rotor shaft 23 also rotates in the same manner. At this time, the intake air supplied to the compressor 12 via the air cleaner 24 is compressed by the rotation of the compressor 22 and then passes through the intercooler 25 and the temperature thereof is lowered. Thereafter, the compressed intake air is supplied to the port and the cylinder 2 of the direct injection type engine 1 through the intake manifold 3.

  An exhaust purification unit 27 including a catalyst 26 as exhaust purification means and a muffler 28 are provided downstream of the exhaust turbine 21 in the exhaust system.

  The direct injector 11d constitutes a specific example of “first fuel injection means” in the present invention, and the port injector 11p constitutes a specific example of “second fuel injection means” in the present invention. ing. Further, the fuel pressure setting unit 301, the injection number setting unit 303, the injection control unit 304, the injection period setting unit 302, and the ignition timing control unit 30 constitute one specific example of “control means” in the present invention.

(2) Operation Principle Next, the operation principle of the control device for an internal combustion engine according to the present embodiment will be described with reference to FIGS.

(2-1) Control Process First, a control process in the control device for an internal combustion engine according to the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing the flow of control processing in the control apparatus for an internal combustion engine according to this embodiment. This control process is repeatedly executed by the ECU at a predetermined cycle such as several tens of microseconds or several microseconds. FIG. 5 shows the direct injection ratio, the ratio injected in the second half of the compression stroke, and the injection timing with respect to the concentration of hydrocarbon HC or carbon monoxide CO contained in the exhaust gas in the control apparatus for an internal combustion engine according to the present embodiment. 6 is a graph showing the relationship (FIG. 5A, FIG. 5B, and FIG. 5C). FIG. 6 is a timing chart showing various processing timings in the control apparatus for an internal combustion engine according to the present embodiment. FIG. 7 is a schematic diagram schematically showing how fuel is injected into the cylinder of the internal combustion engine according to the present embodiment.

  As shown in FIG. 4, first, under the control of the ECU 30, it is determined whether or not the catalyst needs to be warmed up to quickly increase the temperature of the catalyst (step S10). Here, when it is determined that the catalyst needs to be warmed up to quickly increase the temperature of the catalyst (step S10: Yes), secondary air is supplied to the exhaust passage by the air supply unit under the control of the ECU 30. It is determined whether or not so-called AI (Air Injection) is being executed (step S11). Here, "secondary air" according to the present embodiment means air mainly intended to be directly supplied to the exhaust system of the internal combustion engine, and is supplied to the intake system of the internal combustion engine. This is different from air whose main purpose is to be combusted in a cylinder of an internal combustion engine. Typically, this secondary air is supplied to the exhaust passage to raise the temperature of the catalyst. Here, when it is determined by the air supply means that secondary air is being supplied to the exhaust passage (step S11: Yes), a value A indicating the direct injection ratio under the control of the ECU 30, and A value 1-A indicating the port injection ratio is set (step S101). In particular, the value A indicating the direct injection ratio when the secondary air is supplied is compared with the value B indicating the direct injection ratio when the secondary air described later is not supplied. Is set to be large.

  Thus, when the secondary air is supplied to the exhaust passage, the intake air is sucked into the cylinder of the internal combustion engine due to the increased direct injection ratio compared to the case where the secondary air is not supplied. In the air-fuel mixture, the degree of local or partial fuel concentration (so-called rich state) is increased compared to the case where secondary air is not supplied. The direct injection ratio constitutes one specific example of the “first ratio” according to the present invention. Thereby, the concentration of hydrocarbon HC or carbon monoxide CO in the exhaust gas when secondary air is supplied to the exhaust passage is the same as that of HC or CO in the exhaust gas when secondary air is not supplied. Increased compared to concentration. Specifically, according to a study by the inventors of the present application, as shown in FIG. 5A, as the direct injection ratio is increased, the concentration of hydrocarbon HC or carbon monoxide CO contained in the exhaust gas increases. It has been found that Accordingly, even if the air-fuel ratio of the exhaust gas when the secondary air is supplied to the exhaust passage is the same as the air-fuel ratio of the exhaust gas when the secondary air is not supplied, the exhaust system It is possible to further promote the chemical reaction in the interior of the catalyst and in the catalyst, speed up the temperature rise of the catalyst, activate the catalyst early, and purify the exhaust gas more appropriately.

  As a result, when secondary air is supplied to the exhaust passage, it is possible to effectively suppress the fuel injection from being significantly increased in order to improve the purification efficiency of the catalyst, and the exhaust gas It is possible to purify the gas more efficiently and more appropriately.

  More specifically, the value A indicating the direct injection ratio and the value 1-A indicating the port injection ratio are the values that are performed in the first half and the second half of the intake stroke and the compression stroke in one cycle shown in FIG. It may mean the ratio between the injection amount of the jet injection and the injection amount of the port injection performed in the first half of the intake stroke and the compression stroke in one cycle shown in FIG.

  Next, under the control of the ECU 30, a value C indicating a first predetermined amount of fuel that is directly injected at the time when the compression stroke of the internal combustion engine approaches the top dead center is set (step S201). In particular, a value C indicating a first predetermined amount of fuel that is directly injected at a time approaching the top dead center (TDC) of the compression stroke of the internal combustion engine when supplying secondary air is described later. When the secondary air is not supplied, it is set to be larger than the value D indicating the first predetermined amount to be injected at the time when the compression stroke approaches the top dead center. The value C and the value D may be expressed by a direct injection ratio, or may be expressed by a ratio of a first predetermined amount with respect to the total amount injected by the direct injection injector in one cycle. Here, the “timing close to the top dead center of the compression stroke” according to the present embodiment means a timing included in the latter half of the compression stroke, such as 270 degrees to 360 degrees in the crank angle. In particular, the “timing close to the top dead center of the compression stroke” according to the present embodiment is a state where the concentration of fuel is locally or partially high (so-called rich in the vicinity of the spark plug in the combustion chamber of the cylinder of the internal combustion engine). As a value obtained by adding a slight margin to a value indicating a time at which the degree of formation of the (state) is maximized, it can be individually and specifically obtained by experiment, theoretical, empirical, simulation, or the like. Specifically, in the second half of the compression stroke in one cycle shown in FIG. 6, the first predetermined amount of fuel to be injected is directly injected.

  As a result, when secondary air is supplied to the exhaust passage, the ignition in the combustion chamber of the cylinder of the internal combustion engine is caused by the first predetermined amount of fuel injected at a timing close to the top dead center of the compression stroke. In the periphery of the plug, the degree of local or partial fuel concentration (so-called rich state) is increased compared to the case where secondary air is not supplied. More specifically, as shown in FIG. 7 (a), the fuel injected at the time of approaching the top dead center of the compression stroke is in a state where the concentration of the fuel is locally or partially concentrated around the spark plug. Is formed in the first half of the compression stroke shown in FIG. 7B, and is larger than that in the case where the piston is located away from the spark plug.

  Thereby, the chemical reaction in the exhaust system or in the catalyst can be further promoted, the exhaust gas purification action can be further promoted, and early activation of the catalyst can be realized. Specifically, according to a study by the inventors of the present application, as shown in FIG. 5B, as the first predetermined amount of fuel directly injected at the time of approaching the top dead center of the compression stroke is increased, It has been found that the concentration of hydrocarbon HC or carbon monoxide CO contained in the exhaust gas increases.

  In addition, the direct injection ratio of the fuel injected in the compression stroke of the internal combustion engine may be set to be larger than the port injection ratio in the intake stroke of the internal combustion engine. As a result, in the air-fuel mixture sucked into the cylinder of the internal combustion engine, the degree of local or partial fuel concentration (so-called rich state) is formed. The direct injection ratio is the port injection ratio. It becomes larger than the smaller case. Thereby, the chemical reaction in the exhaust system or in the catalyst can be further promoted, the exhaust gas purification action can be further promoted, and early activation of the catalyst can be realized.

  Next, under the control of the ECU 30, a value E indicating the injection timing of the first predetermined amount of fuel that is directly injected is set (step S301). In particular, the value E indicating the injection timing of the first predetermined amount of fuel that is directly injected when secondary air is supplied is directly injected when the secondary air described later is not supplied. It is set to be on the retard side as compared with the value F indicating the timing of injection of the first predetermined amount of fuel. As a result, the degree of local or partial fuel concentration (so-called rich state) formed around the spark plug in the combustion chamber of the cylinder of the internal combustion engine prevents secondary air from being supplied. It becomes larger than the case. As a result, stratified combustion is more effectively promoted, and fuel ignition is more reliably performed. Thereby, the chemical reaction in the exhaust system or in the catalyst can be further promoted, the exhaust gas purification action can be further promoted, and early activation of the catalyst can be realized. Specifically, according to the research by the present inventor, as shown in FIG. 5 (c), as the first predetermined amount injection timing of the directly injected fuel is changed to the retarded side, the exhaust gas is changed to the exhaust gas. It has been found that the concentration of contained hydrocarbon HC or carbon monoxide CO is high.

  Next, under the control of the ECU 30, in addition to the set port injection ratio and the direct injection ratio, the port injector 11p and the direct injection injector 11d are driven so that fuel is injected at the set injection timing. (Step S13).

  On the other hand, if it is not determined by the air supply means that secondary air is being supplied to the exhaust passage as a result of the determination in step S11 described above (step S11: No), the direct injection described above is performed under the control of the ECU 30. A value B indicating the injection ratio and a value 1-B indicating the port injection ratio are set (step S102). In particular, the value B indicating the direct injection ratio when the secondary air is not supplied is compared with the value A indicating the direct injection ratio when the secondary air is supplied. Is set to be smaller.

  Next, under the control of the ECU 30, a value D indicating a first predetermined amount of fuel that is directly injected at a time when it approaches the top dead center of the compression stroke of the internal combustion engine is set (step S202). In particular, the value D indicating the first predetermined amount of fuel directly injected at the time when the compression stroke of the internal combustion engine is approached to the top dead center when the secondary air is not supplied is the above-described secondary air. Is set to be smaller than the value C indicating the first predetermined amount to be injected at the time when the compression stroke is close to the top dead center.

  Next, under the control of the ECU 30, a value F indicating the injection timing of the first predetermined amount of fuel that is directly injected is set (step S302). In particular, the value F indicating the injection timing of the first predetermined amount of fuel that is directly injected when the secondary air is not supplied is directly injected when the secondary air is supplied. It is set so as to be on the advance side as compared with the value E indicating the injection timing of the first predetermined amount of fuel.

  On the other hand, as a result of the determination in step S10 described above, when it is determined that it is not necessary to warm up the catalyst to quickly increase the temperature of the catalyst (step S10: No), based on the normal map under the control of the ECU 30, A port injection ratio, a direct injection ratio, and an injection timing are set (step S12).

(2-2) Secondary Injection Control Processing Next, secondary injection control processing in the control apparatus for an internal combustion engine according to the present embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing the flow of the secondary injection control process in the control apparatus for an internal combustion engine according to this embodiment. This control process is repeatedly executed by the ECU at a predetermined cycle such as several tens of microseconds or several microseconds. In addition, processes that are substantially the same as the processes described in FIG. 4 are given the same step numbers, and descriptions thereof are omitted as appropriate.

  As shown in FIG. 8, after step S10 described above, as a result of the determination in step S11, the air supply means determines that secondary air is being supplied to the exhaust passage (step S11: Yes). ) Under the control of the ECU 30, a secondary fuel injection timing of the fuel that is directly injected at the timing when the internal combustion engine changes from the expansion stroke to the exhaust stroke is set (step S401). In particular, the value G indicating the injection timing of the secondary fuel when the secondary air is supplied is compared with the value H indicating the injection timing when the secondary air is not supplied. It is set to be close to the bottom dead center (BDC) that changes to the exhaust stroke. Specifically, the secondary fuel is directly injected near the bottom dead center where the expansion stroke changes to the exhaust stroke in one cycle shown in FIG. Here, “close to bottom dead center” according to the present embodiment means that the fuel injected in the recess in the upper part of the piston, that is, the piston cavity, is locally around the spark plug due to the spray formation effect or the like. Alternatively, it means the position of the piston that is determined depending on the state in which the concentration of fuel is partially high (so-called rich state) is hardly formed or the degree of formation is remarkably low.

  As a result, in the vicinity of the ignition plug in the combustion chamber of the cylinder of the internal combustion engine, a state in which the concentration of fuel not intended for combustion in the expansion stroke or the exhaust stroke is not formed (so-called rich state) is not formed or is formed. Is significantly reduced, so that the spark plug can be prevented from being blown (burring), and the spark plug is unintentionally conducting due to the crack in the spark. Can be prevented. More specifically, as shown in FIG. 7 (b), the secondary fuel injected at the time of approaching the vicinity of the bottom dead center where the expansion stroke changes to the exhaust stroke reaches a wide range in the combustion chamber in the cylinder. Spread. Accordingly, for example, in the first half of the expansion stroke and the second half of the exhaust stroke shown in FIG. 7A, the periphery of the spark plug is compared with the case where secondary injection is performed when the piston is close to the spark plug. However, the degree to which the fuel concentration is locally or partially formed is significantly reduced.

  As a result, when the secondary fuel is injected into the exhaust passage in the expansion stroke or the exhaust stroke, it is possible to prevent the secondary fuel from adversely affecting the spark plug. Appropriate combustion can be achieved.

  In particular, in addition to the direct injection, the port injection, and the secondary air supply to the exhaust passage described above, the injection of the secondary fuel temporarily assumes a certain amount in one cycle. In the case of injecting fuel, a fixed amount of fuel is injected in the intake stroke, compression stroke, and expansion compared to the concentrated injection in the intake stroke and compression stroke, which are the fuel injection timings in the direct injection and port injection described above. It is possible to spray in a distributed manner over the stroke and the discharge stroke. As a result, the amount of fuel to be directly injected into the cylinder of the internal combustion engine can be kept within a range where appropriate combustion can be realized in the cylinder. If a certain amount of fuel is injected into the cylinder intensively during the intake stroke or compression stroke, it may be too rich around the spark plug in the combustion chamber of the cylinder of the internal combustion engine, and combustion may not be performed properly. Will occur. On the other hand, in this embodiment, in addition to the fuel injection and the secondary air supply to the exhaust passage in the direct injection and port injection described above, the secondary fuel injection is dispersed. As a result, proper combustion is achieved in the cylinder.

  In addition to this, the amount of secondary fuel injection can be determined appropriately and with high accuracy in accordance with the amount of secondary air supplied to the exhaust passage. It is possible to promote the chemical reaction in the catalyst more appropriately, further promote the exhaust gas purification action, and realize early activation of the catalyst.

  Next, under the control of the ECU 30, the direct injection injector 11d is driven so that secondary fuel is injected at the set injection timing in addition to the set direct injection ratio (step S14). ).

(3) Other Embodiments (3-1) Control Processing Next, control processing in an internal combustion engine control device according to another embodiment will be described with reference to FIGS. 9 to 11. FIG. 9 is a flowchart showing the flow of control processing in the control apparatus for an internal combustion engine according to another embodiment. FIG. 10 is another flowchart showing a flow of control processing in the control apparatus for an internal combustion engine according to another embodiment. FIG. 11 is another flowchart showing a flow of control processing in the control apparatus for an internal combustion engine according to another embodiment. Note that these control processes are repeatedly executed by the ECU at a predetermined cycle such as several tens of microseconds or several microseconds.

  As shown in FIG. 9, steps S202 and S302 may be omitted in the control process in FIG. 4 described above. Thereby, the load of the control process regarding the direct injection ratio and the port injection ratio in the ECU 30 can be reduced.

  Alternatively, as shown in FIG. 10, steps S102 and S302 may be omitted in the control process in FIG. 4 described above. Thereby, the load of the control process regarding the injection timing in the ECU 30 can be reduced.

  Alternatively, as shown in FIG. 11, steps S102 and S202 may be omitted in the control process in FIG. 4 described above. Thereby, the load of the control process regarding the injection timing in the ECU 30 can be reduced.

  In the above-described embodiment, the internal combustion engine including the supercharger including the exhaust turbine 21 and the compressor 22 is described. However, the internal combustion engine may not include the supercharger.

  The present invention is not limited to the above-described embodiments, and may be implemented in various forms. For example, the present invention is not limited to a gasoline engine, and may be applied to various internal combustion engines that use diesel gasoline or other fuels.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and the control of the internal combustion engine accompanying such a change. The apparatus is also included in the technical scope of the present invention.

It is a block diagram which shows notionally the basic composition of the port which concerns on this embodiment, and a cylinder injection type engine. It is sectional drawing which shows notionally the cross section of the port which concerns on this embodiment, and a cylinder injection type engine. It is sectional drawing which shows notionally the cross section of the injector with which the port which concerns on this embodiment, and a cylinder injection type engine are provided. 3 is a flowchart showing a flow of control processing in the control device for an internal combustion engine according to the present embodiment. The relationship between the direct injection ratio, the ratio injected in the second half of the compression stroke, and the injection timing with respect to the concentration of hydrocarbon HC or carbon monoxide CO contained in the exhaust gas in the control apparatus for an internal combustion engine according to the present embodiment is shown. FIG. 5 is a graph (FIG. 5A, FIG. 5B, and FIG. 5C). 4 is a timing chart showing various processing timings in the control apparatus for an internal combustion engine according to the present embodiment. It is the schematic diagram which showed a mode that the fuel was injected in the cylinder of the internal combustion engine which concerns on this embodiment. 6 is a flowchart showing a flow of a secondary injection control process in the control apparatus for an internal combustion engine according to the present embodiment. It is one flowchart which showed the flow of the control processing in the control apparatus of the internal combustion engine which concerns on other embodiment. It is the other flowchart which showed the flow of the control processing in the control apparatus of the internal combustion engine which concerns on other embodiment. It is the other flowchart which showed the flow of the control processing in the control apparatus of the internal combustion engine which concerns on other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Port and cylinder injection type engine 2 Cylinder 3 Intake manifold 4 Exhaust manifold 5 Piston 6 Cavity 7 Intake port 8 Exhaust port 11d Direct injection injector 11p Port injector 12 Knocking sensor 13 Spark plug 14 Fuel supply unit 15 Fuel pipe 16 Fuel tank 21 Exhaust turbine 22 Compressor 23 Rotor shaft 24 Air cleaner 25 Intercooler 26 Catalyst 27 Exhaust purification unit 28 Muffler 29 Air supply means 30 ECU
301 Fuel Pressure Setting Unit 302 Injection Period Setting Unit 303 Injection Number Setting Unit 304 Injection Control Unit 305 Ignition Timing Control Unit

Claims (5)

First fuel injection means capable of injecting a first predetermined amount of fuel into a cylinder of the internal combustion engine;
Second fuel injection means capable of injecting a second predetermined amount of fuel into the intake passage of the internal combustion engine;
An exhaust purification means for purifying exhaust gas provided in an exhaust passage of the internal combustion engine;
Air supply means capable of supplying secondary air to the exhaust passage;
The first ratio of the first predetermined amount with respect to the total injection amount that is the sum of the first predetermined amount and the second predetermined amount and the second ratio of the second predetermined amount with respect to the total injection amount are changed. In addition to controlling at least one of the first fuel injection means and the second fuel injection means, the first ratio in the case where the secondary air is supplied is expressed as the secondary air. A control means for controlling the at least one injection means so as to be larger than the first ratio when not supplied.   The control means further uses the secondary air as the first predetermined amount of fuel to be injected at a time approaching the top dead center of the compression stroke of the internal combustion engine when the secondary air is supplied. 2. The first fuel injection unit is controlled to be larger than the first predetermined amount that is injected at a time when the compression stroke is close to the top dead center when not supplied. Control device for internal combustion engine.   When the control means supplies the secondary air, the control means further compares the first ratio of the fuel injected in the compression stroke of the internal combustion engine with the second ratio in the intake stroke of the internal combustion engine. 3. The control apparatus for an internal combustion engine according to claim 1, wherein the at least one injection unit is controlled to be large.   The control means further supplies the secondary air at an injection timing for injecting at least one of the first predetermined amount and the second predetermined amount when the secondary air is supplied. The at least one injection unit is controlled so as to be changed to a retarded angle as compared with an injection timing at which the at least one fuel is injected when not. The control apparatus for an internal combustion engine according to the item. The first fuel injection means is further capable of injecting secondary fuel in an expansion stroke or an exhaust stroke of the internal combustion engine,
The control means compares the injection timing of the secondary fuel when the secondary air is supplied with the injection timing when the secondary air is not supplied, and the expansion stroke of the internal combustion engine. 5. The control device for an internal combustion engine according to claim 1, wherein the first fuel injection unit is controlled so as to approach a bottom dead center that changes from an exhaust stroke to an exhaust stroke. 6.