JP2006348867A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dual injection system with a port injection valve and an cylinder injection valve for maintaining the properly operated condition of an internal combustion engine by actively controlling an intake valve temperature with the adjustment of an injection rate. <P>SOLUTION: The fuel injection control device sets a port injection rate R in accordance with a basic injection rate R1 which is changed every second corresponding to the operated condition of the engine when the intake valve temperature TV is within a proper range. On the other hand, when the intake valve temperature TV exceeds an upper limit value TVH for the proper range, the port injection rate R is fixed to a value [1] greater than the basic injection rate R1 to reduce the intake valve temperature TV, and when the intake valve temperature TV falls bellow a lower limit valve TVL for the proper range, the port injection rate R is fixed to a value [0] smaller than the basic injection rate R1 to increase the intake valve temperature TV. Thus, the intake valve temperature TV is controlled to be within the proper range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel injection amount control device for an internal combustion engine.

In recent years, fuel injection valves (hereinafter referred to as “port injection valves”) that inject fuel into the intake passage upstream of the intake valves in order to improve combustion efficiency, reduce fuel consumption, and ensure startability at engine startup, etc. And a fuel injection valve (hereinafter referred to as “in-cylinder injection valve”) that directly injects fuel into the combustion chamber (hereinafter also referred to as “in-cylinder”). Internal combustion engines (hereinafter sometimes referred to as “engines”) have been developed (see, for example, Patent Document 1 below).
JP-A-5-2321221

  Hereinafter, a system including two fuel injection valves, that is, a port injection valve and an in-cylinder injection valve for each cylinder, is referred to as a “dual injection system”. The amount of fuel injected from the port injection valve is referred to as “port injection amount”, and the amount of fuel injected from the in-cylinder injection valve is referred to as “in-cylinder injection amount”.

  In the dual injection system described in the above document, the injection ratio, which is the ratio between the port injection amount and the in-cylinder injection amount, is a value based on the engine operating state such as the engine operating speed and the amount of air sucked into the combustion chamber. (Hereinafter referred to as “basic injection ratio”), the port injection amount and the cylinder injection amount are referred to as the air-fuel ratio of the air-fuel mixture supplied to the engine (hereinafter simply referred to as “air-fuel ratio”). Is determined based on the basic injection ratio so as to coincide with the target air-fuel ratio which is the target air-fuel ratio.

  Incidentally, there is an appropriate range for the temperature of the intake valve of the engine. When the temperature of the intake valve deviates from the appropriate range, it becomes difficult to maintain an appropriate operating state of the engine (details will be described later). However, in the dual injection system described in the above document, no consideration is given to the temperature of the intake valve.

  Accordingly, an object of the present invention is to maintain an appropriate operating state of an engine in a fuel injection amount control device for an internal combustion engine applied to a dual injection system by determining the fuel injection amount in consideration of the temperature of the intake valve. It is to provide what is possible. Hereinafter, first, the basic principle employed by the present invention will be described.

  Part of the fuel injected from the port injection valve adheres to the surface of the intake valve. At this time, the area where the fuel adheres to the surface of the intake valve increases as the port injection amount increases. As a result, the amount of heat transfer from the surface of the intake valve, which becomes higher than the attached fuel, to the fuel increases, and as a result, the temperature of the intake valve decreases. In other words, if the port injection amount is increased, the temperature of the intake valve can be decreased, and if the port injection amount is decreased, the temperature of the intake valve can be increased.

  On the other hand, in the dual injection system, by changing the injection ratio, the port injection amount can be changed without changing the total amount of fuel combusted in the cylinder, and the sum of the port injection amount and the in-cylinder injection amount can be changed. The larger the ratio of the port injection amount (hereinafter referred to as “port injection ratio”), the larger the port injection amount.

  From the above, in the dual injection system, if the port injection ratio is increased, the temperature of the intake valve can be decreased, and if the port injection ratio is decreased, the temperature of the intake valve can be increased. This is the basic principle adopted by the present invention.

  The first fuel injection amount control device according to the present invention is determined by an injection ratio determining means that principally determines the injection ratio as a basic injection ratio based on an operating state of the internal combustion engine, and the injection ratio determining means. An injection amount determining means for determining the port injection amount and the in-cylinder injection amount based on an injection ratio is provided.

  The first fuel injection amount control device according to the present invention is characterized by intake valve temperature acquisition means for acquiring an actual temperature of the intake valve as an intake valve temperature acquisition value, and the intake air in which the temperature of the intake valve should not exceed Upper limit value determining means for determining an upper limit value of the temperature of the valve, and when the intake valve temperature acquisition value exceeds the upper limit value, the injection ratio determining means replaces the injection ratio with the basic injection ratio. This is because the port injection amount ratio is determined to be larger than the basic injection ratio.

  The “upper limit value of the temperature of the intake valve” is an upper limit value of the above-described appropriate range of the temperature of the intake valve that can maintain an appropriate operating state of the engine. More specifically, the “upper limit value of the intake valve temperature” is a situation in which deposits are generated on the surface of the intake valve, as described later, or smooth operation of the intake valve, as will be described later. This value is lower than the lower limit value of the temperature range of the intake valve that prevents a proper opening area of the intake valve from being maintained with respect to the crank angle.

  According to the above configuration, when the intake valve temperature acquisition value is equal to or lower than the upper limit value, the injection ratio is determined as the basic injection ratio. On the other hand, when the intake valve temperature acquisition value exceeds the upper limit value, the injection ratio is a value at which the ratio of the port injection amount is larger than the basic injection ratio instead of the basic injection ratio (that is, the port injection ratio is large). Value).

  As a result, when the actual temperature of the intake valve exceeds the upper limit value, the actual temperature of the intake valve can be reduced based on the basic principle described above, and immediately returned to the upper limit value or less. As a result, it is possible to maintain an appropriate operating state of the engine.

  Here, for example, the injection amount determining means is configured such that the sum of the port injection amount and the in-cylinder injection amount is the amount of fuel to be burned in the cylinder in order to make the air-fuel ratio coincide with the target air-fuel ratio (hereinafter referred to as “basic fuel”). The same port injection amount and the same in-cylinder injection amount are determined based on the injection ratio so as to coincide with “injection amount”. Further, the injection amount determining means is attached to the intake valve immediately after the previous port injection and immediately before the current port injection. -The amount of fuel remaining) may be further taken into consideration to determine the port injection amount.

  The intake valve temperature acquisition means may physically detect the actual temperature of the intake valve by a sensor that detects the actual temperature of the intake valve, or may be based on a factor that affects the temperature of the intake valve. The actual temperature of the intake valve may be estimated using a table, function, or the like. When the actual temperature of the intake valve is estimated using the table or the like, in view of the basic principle, the intake valve temperature acquisition means is determined by the injection ratio determination means as a factor that affects the temperature of the intake valve. The intake valve temperature acquisition value is acquired based at least on the determined injection ratio (for example, port injection ratio).

  Further, when the fuel adhesion residual amount estimating means for estimating the fuel adhesion residual amount that is the amount of fuel adhering to the surface of the intake valve by the injection by the port injection means is provided, the intake valve temperature acquisition It is preferable that the means is configured to acquire the intake valve temperature acquisition value based on at least the fuel adhesion residual amount. Here, the “residual amount of fuel adhering” is the amount of fuel adhering to and remaining on the surface of the intake valve immediately after the previous port injection and immediately before the current port injection.

  A large amount of residual fuel adhering at a certain point in time means that the amount of heat transfer from the intake valve, which becomes higher in temperature than the adhering fuel, to the same fuel at a certain point in time is large. In other words, the residual amount of fuel adhesion can also be a factor that affects the temperature of the intake valve. Therefore, according to the above configuration, the actual temperature of the intake valve can be estimated with higher accuracy.

  In the first fuel injection amount control apparatus according to the present invention, the upper limit value determining means determines the upper limit value of the intake valve temperature as a temperature value at which no deposit is generated on the surface of the intake valve. It is suitable to be configured.

  In general, an internal combustion engine is provided with a blow-by gas reduction device that returns blow-by gas to the intake system in order to prevent the blow-by gas from being released into the atmosphere. For this reason, the intake air contains unburned HC components in blow-by gas. It is known that when the temperature of the intake valve exceeds a certain temperature, deposits are generated on the surface of the intake valve due to adhesion of unburned HC components and the like to the surface of the intake valve.

  Once such a deposit is formed on the surface of the intake valve, the shape of the intake valve changes to make it difficult to maintain an appropriate opening area of the intake valve with respect to the crank angle. Therefore, preventing the generation of such deposits is very important in maintaining an appropriate operating state of the engine.

  From the above, if the upper limit value is determined to be a temperature value at which no deposit is generated on the surface of the intake valve as in the above configuration, the generation of deposit can be prevented. The upper limit value can be made an effective value in maintaining the operating state.

  Thus, when the upper limit value is determined to be a temperature at which no deposit is generated on the surface of the intake valve, the upper limit value is based on at least the operating speed of the internal combustion engine and the amount of air taken into the combustion chamber. Is preferably configured to be determined.

  The smaller the amount of the HC component that causes the generation of the deposit during the intake air, the less the deposit is generated and the higher the lower limit value of the temperature at which the deposit is generated. On the other hand, the amount of the HC component that causes the generation of the deposit during intake greatly depends on at least the operating speed of the internal combustion engine and the amount of air taken into the combustion chamber (details will be described later).

  That is, according to the above configuration, the upper limit value can be changed according to the amount of the HC component that causes generation of the deposit during intake. As a result, the upper limit value can be determined to a higher value in accordance with the operating state of the engine within a temperature range in which no deposit is generated, so that opportunities for the injection ratio to be determined as the basic injection ratio can be increased.

  The second fuel injection amount control device according to the present invention comprises the same injection ratio determination means and injection amount determination means as the first fuel injection amount control device. The second fuel injection amount control device according to the present invention is characterized by the same intake valve temperature acquisition means as that of the first fuel injection amount control device, and the lower limit of the temperature of the intake valve that the temperature of the intake valve should not fall below A lower limit value determining means for determining a value, and the injection ratio determining means replaces the injection ratio with the basic injection ratio when the intake valve temperature acquisition value is less than the lower limit value. The ratio of the port injection amount is determined to be a smaller value.

  The “lower limit value of the temperature of the intake valve” is the lower limit value of the appropriate range of the temperature of the intake valve that can maintain an appropriate operating state of the engine. More specifically, the “lower limit value of the intake valve temperature” is that the temperature of the intake valve is too low, and as described later, the “fuel remaining amount” increases and diverges. The port injection amount is a value higher than the upper limit value of the temperature range of the intake valve that makes it difficult to determine an appropriate value for making the air-fuel ratio coincide with the target air-fuel ratio. Alternatively, the “lower limit value of the intake valve temperature” refers to an appropriate opening area of the intake valve with respect to the crank angle due to a situation where the intake valve temperature is too low to prevent smooth operation of the intake valve. This value is higher than the upper limit value of the temperature range of the intake valve that cannot be maintained.

  According to the above configuration, when the intake valve temperature acquisition value is equal to or greater than the lower limit value, the injection ratio is determined as the basic injection ratio. On the other hand, when the intake valve temperature acquisition value is less than the lower limit value, the injection ratio is a value in which the ratio of the port injection amount is smaller than the basic injection ratio instead of the basic injection ratio (that is, the port injection ratio is Decrease value).

  As a result, when the actual temperature of the intake valve becomes lower than the lower limit value, the actual temperature of the intake valve can be increased based on the basic principle described above and immediately return to the upper limit value or more. As a result, it is possible to maintain an appropriate operating state of the engine.

  In the second fuel injection amount control device according to the present invention, the lower limit value determining means attaches the lower limit value of the temperature of the intake valve to the surface of the intake valve by injection by the port injection means. It is preferable that the fuel amount (that is, the fuel adhesion residual amount) is determined to be a temperature value that is equal to or less than a predetermined amount. Here, the “predetermined amount” is a value that is small enough not to make it difficult to determine the port injection amount to an appropriate value for making the air-fuel ratio coincide with the target air-fuel ratio, for example, “0”. It is.

  In general, when the temperature of the intake valve is lower than a certain temperature, the evaporation rate of the fuel adhering / remaining on the surface of the intake valve is reduced, so that the fuel adhering residual amount increases / diversifies. . When such fuel adhesion residual amount divergence occurs, the ratio of the fuel due to evaporation of the fuel attached to and remaining on the intake valve in the total fuel flowing into the cylinder increases, thereby reducing the port injection amount, It becomes difficult to determine an appropriate value for making the air-fuel ratio coincide with the target air-fuel ratio. Therefore, preventing the fuel adhesion residual amount from diverging is very important for making the air-fuel ratio coincide with the target air-fuel ratio.

  From the above, if the lower limit value is determined to be a temperature value at which the fuel adhesion residual amount is equal to or less than a predetermined amount as in the above configuration, divergence of the fuel adhesion residual amount can be prevented. As a result, the lower limit can be made an effective value in stably matching the air-fuel ratio with the target air-fuel ratio.

  Thus, when the lower limit value is determined to be a temperature value at which the fuel adhesion residual amount is equal to or less than a predetermined amount, the lower limit value is determined based on at least the operating speed of the internal combustion engine. Is preferable.

  The smaller the engine operating speed, the longer the period from the previous port injection to the current port injection, and the greater the evaporation amount of fuel adhering to and remaining on the surface of the intake valve during the same period. As a result, the fuel adhering residual amount is less likely to diverge and the upper limit value of the temperature at which the fuel adhering residual amount diverges becomes lower.

  According to the above configuration, the lower limit value can be changed according to the operating speed of the engine. As a result, the lower limit value can be determined to a lower value in accordance with the operating state of the engine within a temperature range in which the fuel adhesion residual amount does not diverge, so that the injection ratio is determined to be the basic injection ratio. Can be increased.

  In addition, a third fuel injection amount control device according to the present invention includes the same injection ratio determination means and injection amount determination means as the first and second fuel injection amount control devices. The features of the third fuel injection amount control device according to the present invention are the same intake valve temperature acquisition means as the first and second fuel injection amount control devices and the same upper limit value as the first fuel injection amount control device. Determining means and lower limit value determining means that is the same as the second fuel injection amount control device, and when the intake valve temperature acquisition value exceeds the upper limit value, the injection ratio determining means Instead of the basic injection ratio, a value that increases the ratio of the port injection amount to the basic injection ratio (that is, a value that increases the port injection ratio) is determined, and the intake valve temperature acquisition value is less than the lower limit value. In this case, the injection ratio is determined to be a value in which the ratio of the port injection amount is smaller than the basic injection ratio instead of the basic injection ratio (that is, the port injection ratio is small). That is.

  According to this, when the actual temperature of the intake valve deviates from the appropriate range described above, it can be immediately returned to the appropriate range based on the basic principle described above. As a result, it is possible to more reliably maintain an appropriate operating state of the engine.

  The fourth fuel injection amount control device according to the present invention includes the same intake valve temperature acquisition means as the first to third fuel injection amount control devices, and an intake valve temperature that is a target value of the intake valve temperature. An intake valve temperature target value determining means for determining a target value; and at least the same intake valve temperature acquired value and the same intake valve temperature target value so that the intake valve temperature acquired value approaches the intake valve temperature target value. And an injection amount determining means for determining the port injection amount and the in-cylinder injection amount based on the injection ratio determined by the injection ratio determining means.

  According to this, the intake valve temperature acquisition value (that is, the actual temperature of the intake valve) is controlled so as to approach the intake valve temperature target value based on the basic principle described above. Therefore, by setting the intake valve temperature target value to, for example, a predetermined value between the upper limit value and the lower limit value (that is, within the appropriate range), the actual temperature of the intake valve is set to the appropriate range. Can be maintained within. As a result, it is possible to maintain an appropriate operating state of the engine.

  In this case, the fourth fuel injection amount control apparatus according to the present invention further includes the same upper limit value determination means as the first and third fuel injection amount control apparatuses, and the intake valve temperature target value determination means includes: It is preferable that the intake valve temperature target value is determined based on the upper limit value. Here, the intake valve temperature target value is determined to be a value equal to or lower than the above upper limit value. Specifically, the intake valve temperature target value is set to a predetermined coefficient (for example, “0.8” in the vicinity of “1” below “1”). The value is multiplied by “1” or more and “1” or less.

  According to this, the actual temperature of the intake valve can be maintained at a value in the vicinity of the upper limit value that is sufficiently higher than the lower limit value and not exceeding the upper limit value. As a result, the evaporation rate of the fuel adhering / residual to the intake valve becomes sufficiently large so that the fuel adhering residual amount can be maintained at “0”, and the fuel adhering residual amount is reliably prevented from diverging. Can do. As a result, it becomes very easy to determine the port injection amount to an appropriate value for matching the air-fuel ratio with the target air-fuel ratio, and the air-fuel ratio can be matched more stably with the target air-fuel ratio.

  Further, in the fourth fuel injection amount control device according to the present invention, the injection ratio determining means is based on the difference so that the difference between the intake valve temperature acquisition value and the intake valve temperature target value becomes “0”. The feedback correction amount may be calculated, and the injection ratio may be feedback controlled based on the feedback correction amount.

  In this case, the injection ratio determination means feedback-corrects the basic injection ratio based on the operating state of the internal combustion engine determined by the injection ratio determination means included in the first to third fuel injection amount control devices according to the present invention. The injection ratio may be determined so that the intake valve temperature acquisition value approaches the intake valve temperature target value by correcting with the amount.

  In any of the above fuel injection amount control apparatuses according to the present invention, the internal combustion engine is configured to have a valve overlap period that is a period during which both the intake valve and the exhaust valve are open. When configured to be changeable according to the state, the injection rate determination means, when the length of the valve overlap period is predicted (currently) to exceed a predetermined length in the future, It is preferable that the ratio is changed and determined to a value for increasing the temperature of the intake valve.

  Here, the “value for increasing the temperature of the intake valve” is, for example, “0” when the port injection ratio is adopted as the injection ratio. As a result, the port injection ratio can be reduced, and as a result, the temperature of the intake valve can be reliably increased based on the basic principle.

  When the valve overlap period exists, the so-called “blow-back” of the burned gas occurs due to the pressure in the intake passage being lower than the in-cylinder pressure during the same period. When the valve overlap period increases, the degree of “blowback” increases, and the fuel adhering to and remaining on the intake valve may scatter to the upstream side of the intake passage. As a result, it may be very difficult to determine the port injection amount to an appropriate value for making the air-fuel ratio coincide with the target air-fuel ratio.

  Therefore, if it is predicted at this time that the length of the valve overlap period will exceed a predetermined length in the future (for example, between the present time and after a predetermined time), the temperature of the intake valve is reduced from the current time. It is considered preferable to increase the residual amount of fuel adheringly by forcibly increasing it.

  The above configuration is based on such knowledge. According to this, at the time when the valve overlap period increases in the future, the residual amount of fuel adhering is already a small value, so that the amount of fuel scattered by “blowback” of burned gas can be reduced. As a result, it is possible to suppress a temporary deterioration of the air-fuel ratio at the time when the valve overlap period increases in the future.

  In any one of the above fuel injection amount control apparatuses according to the present invention, the internal combustion engine is configured to be able to interrupt injection from the port injection means and the in-cylinder injection means in accordance with an operating state of the internal combustion engine. In this case, the injection ratio determination means changes and determines the injection ratio to a value for increasing the temperature of the intake valve when the interruption of the injection from the port injection means and the in-cylinder injection means is released. It is preferable to be configured as described above. Here, the “value for increasing the temperature of the intake valve” is, for example, “0” when the port injection ratio is adopted as the injection ratio as described above. Hereinafter, the interruption of the injection is referred to as “fuel cut”.

  During the fuel cut, heat based on combustion is not generated in the cylinder. Therefore, the temperature of the intake valve at the time when the fuel cut is released is low (for example, it may be less than the lower limit value). As a result, the fuel adhesion residual amount may diverge due to port injection after the fuel cut is released.

  Therefore, after the fuel cut is canceled, it is considered preferable to positively reduce the fuel adhesion residual amount by forcibly increasing the temperature of the intake valve based on the basic principle.

  The above configuration is based on such knowledge. According to this, the divergence of the fuel adhesion residual amount after the time when the fuel cut is released can be prevented, and as a result, the deterioration of the air-fuel ratio after the time when the fuel cut is released can be suppressed. .

  Embodiments of a fuel injection amount control device for an internal combustion engine according to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 shows a schematic configuration of a system in which a fuel injection amount control apparatus according to a first embodiment of the present invention is applied to a spark ignition type multi-cylinder (four-cylinder) internal combustion engine 10 equipped with a dual injection system. The internal combustion engine 10 includes a cylinder block unit 20 including a cylinder block, a cylinder block lower case, an oil pan, and the like, a cylinder head unit 30 fixed on the cylinder block unit 20, and a gasoline mixture in the cylinder block unit 20. And an exhaust system 50 for releasing exhaust gas from the cylinder block 20 to the outside.

  The cylinder block unit 20 includes a cylinder 21, a piston 22, a connecting rod 23, and a crankshaft 24. The piston 22 reciprocates in the cylinder 21, and the reciprocating motion of the piston 22 is transmitted to the crankshaft 24 through the connecting rod 23, whereby the crankshaft 24 rotates. The heads of the cylinder 21 and the piston 22 form a combustion chamber 25 together with the cylinder head portion 30.

  The cylinder head portion 30 includes an intake port 31 communicating with the combustion chamber 25, an intake valve 32 that opens and closes the intake port 31, an intake camshaft that drives the intake valve 32, and continuously changes the phase angle of the intake camshaft. The variable intake timing device 33, the actuator 33 a of the variable intake timing device 33, the exhaust port 34 communicating with the combustion chamber 25, the exhaust valve 35 that opens and closes the exhaust port 34, the exhaust camshaft 36 that drives the exhaust valve 35, and the spark plug 37 , An igniter 38 including an ignition coil that generates a high voltage to be applied to the spark plug 37, a port injection valve 39P for injecting fuel into the intake port 31, and an in-cylinder injection valve 39C for injecting fuel directly into the combustion chamber 25. Yes. The intake valve 32 and the exhaust valve 35 are made of an alloy containing Cr or the like.

  The intake system 40 is provided in an intake pipe 41 including an intake manifold that communicates with the intake port 31 and forms an intake passage together with the intake port 31, an air filter 42 provided at an end of the intake pipe 41, and the intake pipe 41. A throttle valve 43 that makes the opening cross-sectional area of the intake passage variable, and a throttle valve actuator 43a made of a DC motor that constitutes the throttle valve drive means are provided, and although not shown, a blow-by that reduces blow-by gas to the intake passage A gas reduction device is also provided.

  The exhaust system 50 includes an exhaust manifold 51 that communicates with the exhaust port 34, and an exhaust pipe (exhaust pipe) that is connected to the exhaust manifold 51 (actually, a collection portion of the exhaust manifolds 51 that communicate with each exhaust port 34). ) 52, and a three-way catalyst 53 disposed (intervened) in the exhaust pipe 52. The exhaust port 34, the exhaust manifold 51, and the exhaust pipe 52 constitute an exhaust passage.

  On the other hand, this system includes a hot-wire air flow meter 61, a cam position sensor 62, a crank position sensor 63, a water temperature sensor 64, and an exhaust passage upstream of the three-way catalyst 53 (in this example, a set in which the exhaust manifolds 51 are gathered. The air-fuel ratio sensor 65 is provided.

  The hot-wire air flow meter 61 outputs a voltage corresponding to the mass flow rate per unit time of the intake air flowing through the intake pipe 41. An intake air amount (flow rate) Ga is calculated from this output. The cam position sensor 62 generates a signal (G2 signal) having one pulse every time the intake camshaft rotates 90 ° (that is, every time the crankshaft 24 rotates 180 °). This signal also represents the opening / closing timing VT of the intake valve 32.

  The crank position sensor 63 outputs a signal having a narrow pulse every time the crankshaft 24 rotates 10 ° and a wide pulse every time the crankshaft 24 rotates 360 °. This signal represents the operating speed NE. The water temperature sensor 64 detects the temperature of the cooling water of the internal combustion engine 10 and outputs a signal representing the cooling water temperature THW. The air-fuel ratio sensor 65 outputs a current corresponding to the air-fuel ratio of the exhaust gas, and outputs a voltage corresponding to this current. From this output, the air-fuel ratio of the exhaust gas is calculated.

  The electric control device 70 includes a CPU 71 connected by a bus, a routine (program) executed by the CPU 71, a table (look-up table, map), a ROM 72 in which constants and the like are stored in advance, and the CPU 71 temporarily stores data as necessary. This is a microcomputer comprising a RAM 73 for storing data, a backup RAM 74 for storing data while the power is turned on and holding the stored data while the power is shut off, an interface 75 including an AD converter, and the like. .

  The interface 75 is connected to the sensors 61 to 65, supplies signals from the sensors 61 to 65 to the CPU 71, and in response to instructions from the CPU 71, the actuator 33a, the igniter 38, and the port injection valve 39P of the variable intake timing device 33. A drive signal is sent to the in-cylinder injection valve 39C and the throttle valve actuator 43a. As a result, the opening / closing timing VT of the intake valve 32 (and thus the above-described valve overlap period) is changed in accordance with the operating state of the engine. Further, the fuel cut described above is made according to the operating state of the engine.

(Outline of determining method of port injection amount fip and in-cylinder injection amount fic)
Next, a method for determining the fuel injection amount, that is, the port injection amount fip and the in-cylinder injection amount fic by the fuel injection amount control device (hereinafter also referred to as “this device”) configured as described above. Will be described.

  In such a dual injection system, the injection ratio of the port injection amount fip by the port injection valve 39P and the in-cylinder injection amount fic by the in-cylinder injection valve 39C (hereinafter, this port injection ratio R (= fip / ( fip + fic)) is preferably used depending on the engine operating conditions such as the operating speed NE and the cooling water temperature THW.

  For this reason, this apparatus stores in ROM 72 a table that defines the relationship between the engine operating state and the port injection ratio (hereinafter referred to as “basic injection ratio R1”) based on the operating state. . Further, the present apparatus should be combusted in the cylinder in order to make the air-fuel ratio coincide with the target air-fuel ratio abyfr from the in-cylinder intake air amount Mc obtained as described later and the target air-fuel ratio abyfr (theoretical air-fuel ratio stoich). The amount of fuel (that is, the basic fuel injection amount Fbase) is obtained.

  Then, in principle, this apparatus obtains the basic injection ratio R1 based on this table and the current operating state of the engine (operating speed NE, cooling water temperature THW, etc.), and the obtained basic fuel injection amount Fbase and The port injection amount fip and the in-cylinder injection amount fic are determined based on the basic injection ratio R1 and a fuel behavior model (inverse model) of fuel adhesion to the intake valve, which will be described later.

  As described above, the port injection ratio R is changed every moment in principle according to the operating state of the engine. On the other hand, as will be described later, when the actual temperature of the intake valve 32 (intake valve temperature acquisition value TV) deviates from the above-described appropriate range, the present apparatus forces the port injection ratio R regardless of the operating state of the engine. Therefore, the port injection amount fip and the in-cylinder injection amount fic are determined while being fixed to a predetermined specific value. The above is the outline of the method for determining the port injection amount fip and the in-cylinder injection amount fic.

  Hereinafter, before explaining a specific method for determining the port injection amount fip and the in-cylinder injection amount fic, a fuel behavior (adhesion) model used by the present apparatus to determine the port injection amount fip will be described.

(Fuel behavior (adhesion) model)
As conceptually shown in FIG. 2, part of the fuel injected from the port injection valve 39 </ b> P of the cylinder into which the fuel is injected adheres to the surface of the intake valve 32. The fuel adhering to the surface of the intake valve 32 evaporates at an evaporation rate according to the temperature of the intake valve 32, and the fuel that cannot be evaporated remains on the surface of the intake valve 32. Therefore, the present apparatus uses a fuel behavior model using such an adhesion rate and a residual rate representing the behavior of the fuel, and a fuel that is the amount of fuel adhering to and remaining on the surface of the intake valve 32. Find the adhesion residue fw.

  More specifically, as shown in FIG. 3 focusing on the port-injected cylinder, fip is the port injection amount that is the amount of fuel that is port-injected from the port injection valve 39P for the current intake stroke, fw (fw (k-1)) after the previous port injection and immediately before the current port injection, the amount of fuel adhering to and remaining on the surface of the intake valve 32 (fuel adhering residual amount), Pv as fuel The ratio of the amount of fuel remaining on the surface of the intake valve 32 (residual rate) in the residual adhesion amount fw (k-1), and the fuel that adheres to the surface of the intake valve 32 in the port injection amount fip. The amount of fuel remaining on the surface of the intake valve 32 after the current port injection and immediately before the next port injection in the remaining fuel adhesion amount fw (k-1). Becomes Pv · fw (k-1), and newly adheres to the surface of the intake valve 32 of the fuel of the port injection amount fip. The amount of fuel will be Rv · fip. Therefore, the following equation (1) is established for the remaining fuel adhesion amount fw (k) that is the amount of fuel adhering to and remaining on the surface of the intake valve 32 immediately after the next port injection and immediately before the next port injection. To do. The following equation (1), which is a recurrence formula, describes a fuel behavior model, and means for calculating the following equation (1) corresponds to fuel adhesion residual amount estimating means.

fw (k) = Pv · fw (k-1) + Rv · fip (1)

  Further, as described above, the Pv and Rv strongly depend on the temperature of the intake valve 32 that affects the behavior of the fuel adhering to and remaining on the surface of the intake valve 32 (for example, the evaporation speed of the fuel). In addition, the intake air amount Mc, the operating speed NE, the opening / closing timing VT of the intake valve 32, and the coolant temperature THW are also strongly dependent. Therefore, Pv and Rv are determined according to a predetermined table acquired in advance using these values as arguments.

  The above is the outline of the fuel behavior (attachment) model used by the present apparatus. This device uses the Pv and Rv determined in this way and the above equation (1), which is a recurrence formula representing the fuel behavior model, to calculate the remaining fuel adhesion amount fw (k) for each intake stroke. And it updates for every cylinder.

(Specific determination method of port injection amount fip and in-cylinder injection amount fic)
Next, a specific method for determining the port injection amount fip and the in-cylinder injection amount fic will be described. In principle, the present apparatus uses the basic injection ratio R1 and the basic fuel injection amount Fbase in the intake stroke when the intake valve temperature acquisition value TV described later does not deviate from the appropriate range. The port injection amount fip is obtained using an inverse model of the fuel behavior model described later so that the amount of fuel flowing into the fuel matches the required port inflow fuel amount Fc obtained by the following equation (2). The internal injection amount fic is obtained according to the following equation (3). In this way, by considering the residual fuel amount fw, the total amount of fuel supplied into the cylinder can coincide with the basic fuel injection amount Fbase, and as a result, the air-fuel ratio can coincide with the target air-fuel ratio stoich. it can.

Fc = Fbase · R1 (2)

fic = Fbase ・ (1-R1) (3)

  Hereinafter, an inverse model of the fuel behavior model will be described. The inverse model of the fuel behavior model is that the amount of fuel that flows into the cylinder without adhering to the intake valve 32 among the fuel injected into the port, and the fuel that flows into the cylinder among the fuel adhering to the intake valve 32 This is a model that calculates the port injection amount fip required to cause the required port inflow fuel amount Fc calculated by the above equation (2) to flow into the cylinder in consideration of the amount.

  Fuel adhesion, which is the amount of fuel adhering and remaining on the surface of the intake valve 32 immediately after the previous port injection of the fuel injection cylinder and immediately before the current port injection, which has already been obtained by the above equation (1) Using the residual quantity fw (k-1) and the above-mentioned Pv and Rv determined as described above, it is assumed that the fuel of the port injection quantity fip is injected into the cylinder for the current intake stroke. The amount Fin of inflowing fuel is expressed by the following equation (4) (see FIG. 3).

Fin = (1−Rv) ・ fip + (1−Pv) ・ fw (k−1) (4)

  Accordingly, the port injection amount fip required for the required port inflow fuel amount Fc calculated by the above equation (2) to flow into the cylinder in the current intake stroke is the same as the fuel amount Fin in the above equation (4). It can be obtained by solving for the port injection amount fip by replacing the required port inflow fuel amount Fc. The calculation result is as shown in the following equation (5). This equation (5) is a mathematical expression of the inverse model of the fuel behavior model. In principle, this apparatus obtains the port injection amount fip according to the equation (5). The above is the outline of the inverse model of the fuel behavior model used for obtaining the port injection amount fip.

fip = (Fc− (1−Pv) ・ fw (k−1)) / (1−Rv) (5)

(Control of intake valve temperature based on port injection ratio)
By the way, the temperature of the intake valve 32 may change from moment to moment according to the operating state of the engine. Here, as described above, when the temperature of the intake valve 32 exceeds a certain temperature, a deposit is generated on the surface of the intake valve 32.

  When a deposit is generated on the surface of the intake valve 32, the shape of the intake valve 32 changes. As a result, an appropriate opening area of the intake valve 32 with respect to the crank angle is not maintained, and an appropriate in-cylinder intake air amount Mc cannot be obtained. As a result, it becomes impossible to obtain proper engine output characteristics and the like.

  In addition, when deposit is generated on the surface of the intake valve 32, the material of the surface of the intake valve 32 changes and the thermal conductivity and the like of the surface changes, so that the behavior of the fuel adhering to and remaining on the intake valve 32 Changes. As a result, the estimation error included in the residual rate Rv and the sticking rate Pv of the fuel behavior model determined without considering the change in the thermal conductivity and the like increases, and the fuel sticking residual amount fw is accurately estimated. become unable.

  On the other hand, when the temperature of the intake valve 32 falls below a certain temperature, the above-mentioned “divergence of the remaining fuel adhesion amount” may occur. When this “divergence of the remaining amount of fuel adhering” occurs, the fuel adhering to and remaining on the intake valve 32 in the amount of total fuel flowing into the cylinder from the intake passage (that is, the fuel amount Fin of the above equation (4)) Of fuel that indirectly flows into the cylinder due to evaporation of the fuel (that is, the value expressed by the second term on the right side of the above equation (4) "(1-Pv) · fw (k-1)") The proportion of will increase.

  Here, the amount of fuel indirectly flowing into the cylinder represented by “(1-Pv) · fw (k-1)” is the amount of fuel directly flowing into the cylinder by port injection (that is, It is considered that the estimation error includes a larger estimation error than the first term “(1-Rv) · fip” on the right side of the equation (4). Therefore, when “divergence of the remaining amount of fuel adhesion” occurs, it is difficult to determine the port injection amount fip to an appropriate value for making the air-fuel ratio coincide with the target air-fuel ratio stoich.

  From the above, it is necessary to prevent the generation of deposits on the surface of the intake valve 32 and the “divergence of the remaining amount of fuel adhesion”. For this purpose, a temperature lower than the lower limit value of the temperature range in which deposits are generated (hereinafter referred to as “upper limit TVH”) and an upper limit value of the temperature range in which “the divergence of the fuel adhesion amount” occurs. Higher temperature (hereinafter referred to as “lower limit TVL”), and the actual temperature of the intake valve 32 (the intake valve temperature acquisition value TV described later) is not less than the lower limit TVL and not more than the upper limit TVH. It is necessary to control to be within the proper range.

<Basic principle of temperature control of intake valve>
By the way, in the dual injection system, the temperature of the intake valve 32 can be positively controlled by adjusting the port injection ratio R. Hereinafter, this principle (basic principle) will be described.

  As described above, part of the fuel of the port injection amount fip adheres to the surface of the intake valve 32. When the fuel adheres to the surface of the intake valve 32, heat transfer from the intake valve 32, which has a higher temperature than the attached fuel, to the attached fuel occurs. The amount of heat transfer increases as the port injection amount fip increases and the area where fuel adheres to the intake valve 32 increases. An increase in the amount of heat transfer means that the temperature of the intake valve 32 decreases.

  Accordingly, by increasing the port injection amount fip from a state where the engine is in a certain steady operation state and the temperature of the intake valve 32 is constant at a certain temperature, the temperature of the intake valve 32 is changed to the certain temperature. Can be lower. In other words, if the port injection amount fip is increased, the temperature of the intake valve 32 can be decreased, and if the port injection amount fip is decreased, the temperature of the intake valve 32 can be increased.

  On the other hand, in the dual injection system, by changing the port injection ratio R, the port injection amount fip can be changed without changing the total amount of fuel combusted in the cylinder (that is, the basic fuel injection amount Fbase). As the port injection ratio R increases, the port injection amount fip increases.

  From the above, in the dual injection system, if the port injection ratio R is increased, the temperature of the intake valve 32 can be decreased, and if the port injection ratio R is decreased, the temperature of the intake valve 32 can be increased. it can. This is the basic principle of temperature control of the intake valve based on the port injection ratio R.

<Details of intake valve temperature control>
Using the basic principle described above, when the actual temperature of the intake valve 32 exceeds the upper limit TVH, the port injection amount fip is determined based on the port injection ratio R that is larger than the basic injection ratio R1. The actual temperature of the intake valve 32 can be lowered, and as a result, the actual temperature of the intake valve 32 can be returned to the upper limit value TVH or less. In this case, if the port injection ratio R is set to the maximum value “1”, the effect of reducing the temperature of the intake valve 32 based on the basic principle is most exerted, so the actual temperature of the intake valve 32 is most quickly set. It can be returned to the upper limit value TVH or less.

  Similarly, when the actual temperature of the intake valve 32 falls below the lower limit value TVL, the port injection amount fip is determined based on the port injection ratio R that is smaller than the basic injection ratio R1, thereby causing the actual intake valve 32 to actually operate. The temperature can be raised, and as a result, the actual temperature of the intake valve 32 can be returned to the lower limit value TVL or higher. In this case, if the port injection ratio R is set to the minimum value “0”, the effect of increasing the temperature of the intake valve 32 based on the basic principle is most exerted, so that the actual temperature of the intake valve 32 is most quickly set. It can be returned to the lower limit TVL or higher.

  Therefore, when the actual temperature of the intake valve 32 (the intake valve temperature acquisition value TV described later) is within the appropriate range, the present device determines the port injection amount fip and the in-cylinder injection amount fic as described above. In principle, it is determined based on the basic injection ratio R1 (see the above formulas (2), (3) and (5)).

  On the other hand, this device determines the port injection amount fip and the in-cylinder injection amount fic so that the port injection ratio R = 1 when the actual temperature of the intake valve 32 exceeds the upper limit value TVH. In this case, the port injection amount fip is a value obtained by replacing the required port inflow fuel amount Fc with the basic fuel injection amount Fbase in the above equation (5), and the in-cylinder injection amount fic is “0”.

  In addition, the present apparatus determines the port injection amount fip and the in-cylinder injection amount fic so that the port injection ratio R = 0 when the actual temperature of the intake valve 32 falls below the lower limit value TVL. In this case, the port injection amount fip is “0”, and the in-cylinder injection amount fic is equal to the basic fuel injection amount Fbase.

  As described above, the present apparatus controls the intake valve temperature acquisition value TV so as to be within an appropriate range not less than the lower limit value TVL and not more than the upper limit value TVH based on the basic principle. Hereinafter, a method for determining the upper limit value TVH and the lower limit value TVL, and a method for acquiring the intake valve temperature acquisition value TV, which is the actual temperature of the intake valve 32, required for such control will be described.

<Determination method of upper limit TVH>
As described above, the upper limit value TVH is determined to be lower than the lower limit value of the temperature range in which deposits are generated on the surface of the intake valve 32 in this example. Therefore, in order to determine the upper limit value TVH, it is necessary to acquire the lower limit value of the temperature range in which the deposit is generated.

  By the way, this deposit is generated when the unburned HC component contained in the blow-by gas returned to the intake system by the blow-by gas reduction device adheres to the surface of the high-temperature intake valve 32. Therefore, the smaller the amount (average value) of the unburned HC component in the intake air that can contact (collision) with the intake valve 32 per unit time is, the more difficult it is to generate a deposit. The difficulty in generating a deposit means that the lower limit value of the temperature range in which the deposit is generated becomes higher.

  On the other hand, the unburned HC component or the like in the intake air contacts the intake valve 32 mainly during the valve opening period of the intake valve 32 (that is, while the intake air flows into the cylinder). Here, since the time interval from the previous valve opening period of the intake valve 32 to the valve opening period of the current intake valve 32 becomes longer as the operation speed NE is smaller, the frequency of the opening period of the intake valve 32 (accordingly, therefore) The frequency at which the unburned HC component etc. contacts the intake valve 32) decreases as the operating speed NE decreases. From the above, the average value per unit time of the unburned HC component and the like that can come into contact with the intake valve 32 becomes smaller as the operating speed NE is smaller. As a result, the lower the operating speed NE, the higher the lower limit value of the temperature range in which deposits are generated.

  In addition, the smaller the total amount of fuel injected into the cylinder, and thus the smaller the in-cylinder intake air amount Mc, the greater the crankcase from the gap between the inner wall surface of the cylinder 21 and the piston ring of the piston 22 during the compression stroke of the engine. The amount of unburned HC components that leak into As a result, the smaller the in-cylinder intake air amount Mc, the smaller the concentration of unburned HC components and the like in the intake air. Therefore, the average value per unit time of the unburned HC component and the like that can come into contact with the intake valve 32 decreases as the in-cylinder intake air amount Mc decreases. As a result, the lower the in-cylinder intake air amount Mc, the higher the lower limit value of the temperature range in which deposits are generated.

  From the above, the lower limit value of the temperature range in which the deposit is generated greatly depends on the operating speed NE and the in-cylinder intake air amount Mc, and can be obtained based on these. Therefore, the present apparatus determines the upper limit value TVH according to a predetermined table using the operating speed NE and the in-cylinder intake air amount Mc as arguments.

  Thus, the upper limit value TVH is set to a higher value as the operating speed NE is smaller and the in-cylinder intake air amount Mc is smaller. As a result, the upper limit value TVH can be determined to a higher value in accordance with the operating speed NE and the in-cylinder intake air amount Mc within a temperature range in which no deposit is generated, so that the port injection amount fip and the in-cylinder injection amount fic are Opportunities determined based on the basic injection ratio R1 can be increased.

<Determination method of lower limit TVL>
As described above, in this example, the lower limit value TVL is determined to be higher than the upper limit value of the temperature range in which “divergence of the remaining amount of fuel adhesion” occurs. Therefore, in order to determine the lower limit value TVL, it is necessary to acquire the upper limit value of the temperature range in which “the divergence of the fuel adhesion residual amount” occurs.

  In this example, from the viewpoint of most reliably preventing the occurrence of “divergence of fuel adhesion amount”, the fuel adhesion residual amount fw is set to “0” as the upper limit value of the temperature range where “divergence of fuel adhesion amount” occurs. The upper limit of the temperature range that cannot be maintained is adopted.

  By the way, the smaller the operation speed NE, the longer the period from the previous port injection to the current port injection (and hence the closing period of the intake valve 32). As a result, the amount of fuel adhering / residual to the intake valve 32 evaporates during the period increases, and the fuel adhering residual amount fw is easily maintained at “0”. This means that the lower the operation speed NE, the lower the upper limit value of the temperature range in which the remaining fuel adhesion amount fw cannot be maintained at “0”.

  From the above, the upper limit value of the temperature range in which the fuel adhesion residual amount fw cannot be maintained at “0” largely depends on the operation speed NE and can be obtained based on the operation speed NE. Therefore, the present apparatus determines the lower limit value TVL according to a predetermined table having the operation speed NE as an argument.

  Thereby, the lower limit value TVL is set to a lower value as the operation speed NE is lower. As a result, the lower limit value TVL can be determined to a lower value according to the operating speed NE within the temperature range in which the fuel adhesion residual amount fw can be maintained at “0” (corresponding to the predetermined amount), and the port injection amount fip , And the in-cylinder injection amount fic can be increased on the basis of the basic injection ratio R1.

<Acquisition method of intake valve temperature acquisition value TV>
The temperature of the intake valve 32 greatly depends on the port injection ratio R, as can be easily understood in view of the basic principle. In addition, the temperature of the intake valve 32 is greatly influenced by the in-cylinder intake air amount Mc and the cooling water temperature THW.

  Further, the temperature of the intake valve 32 also greatly depends on the fuel adhesion residual amount fw, and the fuel adhesion residual amount fw is large even if the port injection ratio R, the cylinder intake air amount Mc, and the cooling water temperature THW are constant. As the temperature of the intake valve 32 becomes lower. This is based on the fact that when the residual fuel amount fw at the present time is large, the heat transfer amount from the intake valve 32 to the fuel adhering to and remaining on the intake valve 32 up to the present time becomes large.

  From the above, this apparatus obtains the intake valve temperature instantaneous value TVp based on a predetermined table using the port injection ratio R, the in-cylinder intake air amount Mc, the coolant temperature THW, and the fuel adhesion residual amount fw as arguments. The intake valve temperature acquisition value TV, which is the actual temperature of the intake valve 32, is acquired by performing predetermined first-order lag processing on the obtained intake valve temperature instantaneous value TVp.

  FIG. 4 shows the relationship between the in-cylinder intake air amount Mc and the port injection ratio R, and the intake valve temperature instantaneous value TVp, obtained from the predetermined table when the cooling water temperature THW and the fuel adhesion residual amount fw are constant. It is the graph which showed. As can be understood from FIG. 4, the intake valve temperature instantaneous value TVp is determined to be larger as the in-cylinder intake air amount Mc is larger. Further, the intake valve temperature instantaneous value TVp is determined to be smaller as the port injection ratio R is larger. This is in line with the basic principle described above. The above is the concept of controlling the temperature of the intake valve based on the port injection ratio.

(Actual operation)
Next, an actual operation of the electric control device 70 will be described with reference to a series of flowcharts shown in FIGS. 5 and 6.

  The CPU 71 performs a series of routines for calculating the port injection amount fip, the in-cylinder injection amount fic, and the fuel injection instruction shown in the flowcharts of FIGS. 5 and 6, and determining that the crank angle of each cylinder is before the intake top dead center. Each time a predetermined crank angle (for example, BTDC 90 ° CA) is reached, it is repeatedly executed for each cylinder.

  Therefore, when the crank angle of an arbitrary cylinder reaches the predetermined crank angle, the CPU 71 starts processing from step 500 and proceeds to step 502, and the intake air flow rate Ga measured by the air flow meter 61 and the crank position sensor 63. The in-cylinder intake air amount Mc, which is the intake air amount of the cylinder that reaches the intake stroke, is obtained based on the operation speed NE obtained based on the output and the table MapMc using Ga and NE as arguments.

  Next, the CPU 71 proceeds to step 504, and multiplies the value obtained by dividing the in-cylinder intake air flow rate Mc by the current target air-fuel ratio abyfr (= stoich) by a coefficient α, thereby reducing the air-fuel ratio to the target air-fuel ratio stoich. To obtain the basic fuel injection amount Fbase. The coefficient α is a coefficient that is appropriately changed by air-fuel ratio feedback control or the like based on the output of the air-fuel ratio sensor 65.

  Next, the CPU 71 proceeds to step 506 and performs basic injection based on the operation speed NE, the in-cylinder intake air amount Mc, the coolant temperature THW obtained from the water temperature sensor 64, and the table MapR using NE, Mc, and THW as arguments. The ratio R1 is obtained.

  Subsequently, the CPU 71 proceeds to step 508, where the previous port injection ratio R, the in-cylinder intake air amount Mc, the cooling water temperature THW, the remaining fuel adhesion amount fw (k-1), R, Mc, THW, Based on the table MapTVp (see FIG. 4) having fw (k-1) as an argument, the intake valve temperature instantaneous value TVp is determined. Here, as the remaining fuel adhesion amount fw (k-1), the latest value already updated in step 538, which will be described later, at the time of the previous execution of this routine is used. Further, as the previous port injection ratio R, a value set in any of steps 518, 522, and 524, which will be described later, at the time of the previous execution of this routine is used.

  Next, the CPU 71 proceeds to step 510, and performs the first-order lag processing with the value A as a time constant according to the equation shown in step 510 for the obtained intake valve temperature instantaneous value TVp, and obtains the current intake valve temperature acquisition value. Find TV (k). Here, TV (k−1) is the previous intake valve temperature instantaneous value and is a value that is updated in the subsequent step 540. Steps 508 and 510 correspond to intake valve temperature acquisition means.

  Next, the CPU 71 proceeds to step 512, obtains the upper limit value TVH based on the operation speed NE, the cylinder intake air amount Mc, and the table MapTVH using NE and Mc as arguments, and in step 514, the operation speed A lower limit TVL is obtained based on NE and a table MapTVL using NE as an argument. This step 512 corresponds to the upper limit value determining means, and step 514 corresponds to the lower limit value determining means.

  Next, the CPU 71 proceeds to step 516 to determine whether or not the acquired intake valve temperature acquired value TV (k) is equal to or less than the obtained upper limit value TVH. Proceed to, and fix the port injection ratio R to “1”.

  On the other hand, when the CPU 71 determines “Yes” in the determination in step 516, the CPU 71 proceeds to step 520 and determines whether or not the acquired intake valve temperature acquired value TV (k) is equal to or greater than the calculated lower limit TVL. When the determination is “No”, the process proceeds to step 522 and the port injection ratio R is fixed to “0”.

  If the determination in step 520 is “Yes”, the CPU 71 proceeds to step 524 and sets the port injection ratio R to the basic injection ratio R1 obtained in step 506. These steps 506 and 516 to 524 correspond to the injection ratio determining means.

  Subsequently, the CPU 71 proceeds to step 526 in FIG. 6 to obtain the required port inflow fuel amount Fc based on the obtained basic fuel injection amount Fbase, the obtained port injection ratio R, and the equation (2). Subsequently, in step 528, the in-cylinder injection amount fic is obtained based on the basic fuel injection amount Fbase, the port injection ratio R, and the above equation (3).

  Next, the CPU 71 proceeds to step 530, in which the cooling water temperature THW, the operation speed NE, the in-cylinder intake air amount Mc, the opening / closing timing VT of the intake valve 32, and the intake valve temperature acquisition value TV (k), The adhesion rate Rv and the residual rate Pv are determined based on predetermined tables MapRv and MapPv using THW, NE, Mc, VT, and TV (k) as arguments, respectively.

  Next, the CPU 71 proceeds to step 532 and based on the obtained required port inflow fuel amount Fc, the determined Pv and Rv, the remaining fuel adhesion amount fw (k-1), and the above equation (5). To obtain the port injection amount fip. When the port injection amount fip is a negative value, the port injection amount fip is set to “0”. As the remaining fuel adhesion amount fw (k-1), the latest value already updated in step 538, which will be described later, at the time of the previous execution of this routine is used. Steps 528 and 532 correspond to the injection amount determining means.

  Next, the CPU 71 proceeds to step 534 to instruct the port injection valve 39P of the cylinder that reaches the intake stroke to inject the fuel of the calculated port injection amount fip at a predetermined timing, and the above-described determination. An instruction for injecting the fuel of the in-cylinder injection amount fic at a predetermined time is given to the in-cylinder injection valve 39C of the same cylinder.

  Next, when the CPU 71 proceeds to step 536, based on the determined Pv and Rv, the remaining fuel amount fw (k-1), and the above equation (1), the remaining fuel amount fw (k). Update. Here, as step 508 and step 532, the latest value already updated in the next step 538 at the previous execution of this routine is used as the remaining fuel adhesion amount fw (k-1).

  That is, when the CPU 71 proceeds to step 538, the value of fw (k-1) is updated to the value of fw (k) updated in step 536 at the time of the current execution of this routine, and in subsequent step 540. Similarly, the value of TV (k−1) is updated to the value of TV (k) updated in the above step 510 when this routine is executed this time.

  Then, the CPU 71 proceeds to step 595 and once ends this routine. As described above, the port injection amount fip and the in-cylinder injection amount fic are determined using the fuel behavior model so that the total fuel amount combusted in the cylinder matches the basic fuel injection amount Fbase. Based on the basic principle, the intake valve temperature acquisition value TV (k) is controlled so as to be within an appropriate range not less than the lower limit value TVL and not more than the upper limit value TVH.

  As described above, the fuel injection amount control device for an internal combustion engine according to the first embodiment of the present invention is a dual injection in which two fuel injection valves, that is, a port injection valve 39P and an in-cylinder injection valve 39C, are provided for each cylinder. Applies to internal combustion engine with system. According to the first embodiment, the upper limit value TVH of the appropriate range of the temperature of the intake valve 32 is determined to be a temperature at which no deposit is generated on the surface of the intake valve 32, and the lower limit value TVL of the appropriate range is the fuel adhesion. The temperature at which the residual amount fw can be maintained at “0” is determined.

  When the actual temperature of the intake valve 32 (that is, the intake valve temperature acquisition value TV) is within an appropriate range not less than the lower limit TVL and not more than the upper limit TVH, the port injection amount fip and the in-cylinder injection amount fic It is determined based on the basic injection ratio R1, which is changed from moment to moment according to the operating state.

  On the other hand, when the intake valve temperature acquisition value TV exceeds the upper limit value TVH, the port injection amount fip and the in-cylinder injection are based on the port injection ratio R = 1 in which the ratio of the port injection amount fip is larger than the basic injection ratio R1. The quantity fic (= 0) is determined. As a result, the actual temperature of the intake valve 32 is reduced based on the basic principle and immediately becomes equal to or lower than the upper limit value TVH. Further, when the intake valve temperature acquisition value TV is lower than the lower limit value TVL, the port injection amount fip (= 0) based on the port injection ratio R = 0 in which the ratio of the port injection amount fip is smaller than the basic injection ratio R1. And the in-cylinder injection amount fic are determined. As a result, the actual temperature of the intake valve 32 is increased based on the basic principle and immediately becomes equal to or higher than the lower limit TVL. That is, the actual temperature of the intake valve 32 is controlled so as to be within the appropriate range. As a result, it is possible to prevent the generation of the deposit and the “divergence of the remaining amount of fuel adhesion” and maintain an appropriate operating state of the engine.

  The present invention is not limited to the first embodiment, and various modifications can be employed within the scope of the present invention. For example, in the first embodiment, when the intake valve temperature acquisition value TV exceeds the upper limit TVH, the port injection amount fip and the in-cylinder injection amount fic (= 0) are based on the port injection ratio R = 1. The basic injection ratio R1 is multiplied by a predetermined coefficient (> 1), or a value obtained by adding a predetermined constant (> 0) to the basic injection ratio R1 (if it exceeds “1”) “1”) may be used as the port injection ratio R, and the port injection amount fip and the in-cylinder injection amount fic may be determined based on the port injection ratio R.

  When the intake valve temperature acquisition value TV is lower than the lower limit value TVL, the port injection amount fip (= 0) and the in-cylinder injection amount fic are determined based on the port injection ratio R = 0. The port injection ratio is a value obtained by multiplying the ratio R1 by a predetermined coefficient (<1) or a value obtained by subtracting a predetermined constant (> 0) from the basic injection ratio R1 ("0" if less than "0"). It may be used as R, and the port injection amount fip and the in-cylinder injection amount fic may be determined based on the port injection ratio R.

  In the first embodiment, the upper limit value TVH is determined so as to change according to the operating speed NE and the in-cylinder intake air amount Mc, but may be a constant value. In this case, it is desirable to use the lower limit value of the variable range of the upper limit value TVH in the first embodiment as the constant value.

  Similarly, in the first embodiment, the lower limit value TVL is determined so as to change according to the operation speed NE, but may be a constant value. In this case, it is desirable to use the upper limit value of the variable range of the lower limit value TVL in the first embodiment as the constant value.

  In the first embodiment, the upper limit TVH is determined to be a temperature at which no deposit is generated on the surface of the intake valve 32, but is determined to be “a temperature at which the smooth operation of the intake valve 32 can be maintained”. Also good. In this case, the “temperature at which the smooth operation of the intake valve 32 can be maintained” is, for example, due to the difference in linear expansion coefficient between the shaft portion of the intake valve 32 and the support member that slidably supports the shaft portion. The temperature at which the clearance of the sliding portion between the shaft portion and the support member may vary within an appropriate range (design target range), or the temperature at which the so-called “burning” does not occur at the sliding portion, etc. Is mentioned.

  In the first embodiment, the lower limit value TVL is determined to be a temperature at which the fuel adhesion residual amount fw can be maintained at “0”. The temperature may be determined as follows. The lower limit value TVL may be determined as “a temperature at which the smooth operation of the intake valve 32 can be maintained”. In this case, as “the temperature at which the smooth operation of the intake valve 32 can be maintained”, for example, the clearance of the sliding portion between the shaft portion of the intake valve 32 and the support member is within an appropriate range (within the design target range). ) And the like.

(Second Embodiment)
Next, a fuel injection amount control apparatus according to the second embodiment of the present invention will be described. This fuel injection amount control device is different from the first embodiment in that the temperature of the intake valve 32 (intake valve temperature acquisition value TV) is controlled based on the basic principle described above in order to maintain an appropriate operating state of the engine. Although the same, the intake valve temperature target value TVS that is the target value of the temperature of the intake valve 32 is determined, and the port injection ratio R is feedback controlled so that the intake valve temperature acquisition value TV matches the intake valve temperature target value TVS. This is different from the first embodiment. Therefore, the following description will focus on such differences.

  This fuel injection amount control device obtains the intake valve temperature target value TVS according to the following equation (6). Here, the coefficient β is a positive value equal to or less than “1”, for example, “0.8”. Thus, the intake valve temperature target value TVS is set to a value that is in the vicinity of the upper limit value TVH and does not exceed the upper limit value TVH (that is, a value within the appropriate range). In other words, the intake valve temperature target value TVS is a temperature at which the deposit is not generated, and is set to a value sufficiently higher than the upper limit value of the temperature range in which the fuel adhesion residual amount fw cannot be maintained at “0”. .

TVS = TVH · β (6)

  This apparatus obtains a feedback correction amount DR of the port injection ratio R to bring the intake valve temperature deviation DTV (= intake valve temperature acquired value TV−intake valve temperature target value TVS) close to “0” as described later.

  The apparatus determines the port injection ratio R (0 ≦ R ≦ 1) by adding the feedback correction amount DR to the basic injection ratio R1, and the port injection based on the determined port injection ratio R. The amount fip and the in-cylinder injection amount fic are determined.

  Thus, the intake valve temperature acquisition value TV is actively controlled so as to coincide with the intake valve temperature target value TVS described above. As a result, in the second embodiment, as in the first embodiment, it is possible to prevent the generation of the deposit and the “divergence of the remaining amount of fuel adhesion”.

(Actual operation of the second embodiment)
Hereinafter, an actual operation of the fuel injection amount control apparatus according to the second embodiment will be described. The CPU 71 of this apparatus executes a series of routines shown in the flowcharts of FIGS. 7 and 8 instead of the series of routines shown in FIGS. 5 and 6 executed by the CPU 71 of the second embodiment. 7 and 8, the same steps as those shown in FIGS. 5 and 6 are denoted by the same step numbers as those in FIGS. 5 and 6.

  The CPU 71 performs a series of routines for calculating the port injection amount fip and the in-cylinder injection amount fic and instructing the fuel injection shown in FIGS. 7 and 8, and the predetermined crank angle of each cylinder before the intake top dead center. Each time the crank angle is reached (for example, BTDC 90 ° CA), the process is repeatedly executed for each cylinder.

  Accordingly, when the crank angle of an arbitrary cylinder reaches the predetermined crank angle, the CPU 71 starts processing from step 700 and proceeds to steps 502 to 506 in order, and as described above, the in-cylinder intake air amount Mc and the basic fuel injection amount. Fbase and basic injection ratio R1 are obtained in order.

  Next, the CPU 71 proceeds to step 705 to determine whether or not the injection ratio feedback control condition is satisfied. Here, the injection ratio feedback control condition is satisfied, for example, when all the various sensors used for the feedback control of the port injection ratio R are normal.

  Assuming that the injection ratio feedback control condition is satisfied, the CPU 71 determines “Yes” in step 705 and proceeds to steps 508 and 510 in order, and as described above, the intake valve temperature acquisition value TV (k). Ask for. Here, in step 508, the latest value already updated in step 538 of FIG. 8 described later at the time of the previous execution of this routine is used as the remaining fuel adhesion amount fw (k-1). As the previous port injection ratio R, the value set in step 740, which will be described later, at the time of the previous execution of this routine is used.

  Next, the CPU 71 proceeds to step 512 to obtain the upper limit value TVH as described above, and in the subsequent step 710, the intake valve temperature target value TVS is obtained based on the obtained upper limit value TVH and the above equation (6). Ask. Step 710 corresponds to intake valve temperature target value determining means.

  Subsequently, the CPU 71 proceeds to step 715, and based on the obtained intake valve temperature acquisition value TV (k), the obtained intake valve temperature target value TVS, and the equation described in step 715, the intake valve temperature acquisition value TV (k) is calculated. Obtain the temperature deviation DTV.

  Next, the CPU 71 proceeds to step 720 and, based on the obtained intake valve temperature deviation DTV, the previous intake valve temperature deviation DTVb, and the equation described in step 720, the differential of the intake valve temperature deviation. Find the value DDTV. As the previous temperature deviation DTVb of the intake valve, the latest value already updated in step 730 to be described later at the time of the previous execution of this routine is used. Δt is the time from the previous execution of this routine to the current execution of this routine.

  Next, the CPU 71 proceeds to step 725, in which the intake valve temperature deviation DTV obtained above, the intake valve temperature deviation differential value DDTV obtained, the intake valve temperature deviation integrated value SDTV, and step 725 are entered. A feedback correction amount DR of the port injection ratio R is obtained based on the described formula. As the integral value SDTV of the temperature deviation of the intake valve, the latest value already updated in step 735 described later at the time of the previous execution of this routine is used. Kp, Ki, and Kd are a proportional gain, an integral gain, and a differential gain, respectively.

  Subsequently, at step 730, the CPU 71 updates the previous temperature deviation DTVb of the intake valve as described above, and at step 735 updates the integrated value SDTV of the temperature deviation of the intake valve as described above. In this way, the feedback correction amount DR of the port injection ratio R when the injection ratio feedback control condition is satisfied is determined.

  Next, the CPU 71 proceeds to step 740 in FIG. 8 to add the port injection ratio R (0 ≦ R ≦ 1) to the calculated basic injection ratio R1 and the feedback correction amount DR of the calculated port injection ratio R. Set to value. These steps 715 to 740 correspond to the injection ratio determining means.

  Next, the CPU 71 proceeds to steps 526 to 532 in order, and as described above, the required port inflow fuel amount Fc, the in-cylinder injection amount fic, the adhesion rate Rv, the residual rate Pv, and the port injection amount fip (> 0) are obtained in order. In the following step 534, a fuel injection instruction for the port injection amount fip and the in-cylinder injection amount fic is issued. Then, the CPU 71 proceeds to steps 536 to 540 in order to update the fuel adhesion residual amount fw (k) as described above and prepare fw (k−1) and TV (k−) for the next execution of this routine. After updating 1), the routine proceeds to step 795 to end the present routine tentatively.

  Thus, when the injection ratio feedback control condition is satisfied, the port injection ratio R is feedback-controlled based on the feedback correction amount DR of the port injection ratio R determined in step 725 (step 740). As a result, the temperature deviation DTV of the intake valve is actively controlled so as to become “0”.

  On the other hand, when the injection ratio feedback control condition is not satisfied, the CPU 71 determines “No” when the process proceeds to step 705 in FIG. 7 and proceeds to step 745 to set the feedback correction amount DR of the port injection ratio R to “0”. In step 750, the integral value SDTV of the temperature deviation of the intake valve is set to “0”.

  As described above, when the injection ratio feedback control condition is not satisfied, the feedback correction amount DR of the port injection ratio R is determined to be “0”, so that the port injection ratio R is not feedback controlled. That is, the port injection ratio R is set to a value equal to the basic injection ratio R1.

  As described above, according to the second embodiment of the fuel injection amount control device for an internal combustion engine according to the present invention, the intake valve temperature acquisition value TV is set to the upper limit value while the injection ratio feedback control condition is satisfied. It is actively controlled so as to coincide with the intake valve temperature target value TVS determined to be a value in the vicinity of TVH and not exceeding the upper limit value TVH. As a result, it is possible to prevent the generation of deposits and “divergence of the remaining amount of fuel adhesion”, and it is possible to maintain an appropriate operating state of the engine.

  The present invention is not limited to the second embodiment, and various modifications can be adopted within the scope of the present invention. For example, in the second embodiment, when the injection ratio feedback control condition is not satisfied, the port injection ratio R is always set to a value equal to the basic injection ratio R1. When the injection ratio feedback control condition is not satisfied, as in the first embodiment, when the intake valve temperature acquisition value TV (k) exceeds the upper limit value TVH (therefore, a deposit is generated on the surface of the intake valve 32). May be configured to fix the port injection ratio R to “1”, or when the intake valve temperature acquisition value TV (k) falls below the lower limit value TVL (accordingly, When there is a possibility that the fuel adhesion residual amount fw may diverge), the port injection ratio R may be fixed to “0”.

  In the second embodiment, when the fuel cut made according to the operating state of the internal combustion engine is released (that is, the state in which no heat based on combustion is generated in the cylinder is released), the intake valve The port injection ratio R may be forcibly fixed to “0” until the temperature acquisition value TV is at least equal to or higher than the lower limit value TVL in the first embodiment.

  As a result, the actual temperature of the intake valve 32, which is lower than the lower limit TVL when the fuel cut is released, is forcibly and most rapidly increased based on the basic principle described above, and the fuel adhesion The residual amount fw is actively reduced. As a result, it is possible to reliably prevent the fuel adhesion residual amount fw from diverging and to suppress the deterioration of the air-fuel ratio after the fuel cut is released.

  In the first and second embodiments, the length of the valve overlap period that is changed according to the operating state of the internal combustion engine is predicted to exceed a predetermined length in the future (i.e., In the case where the degree of “blowback” of the burned gas is expected to increase), the port injection ratio R may be forcibly fixed to “0”.

  As a result, the actual temperature of the intake valve 32 is forcibly increased from the present time based on the above basic principle, and if the actual fuel adhesion residual amount is larger than “0” for some reason, the fuel adhesion residual The amount is actively reduced. As a result, the amount of fuel scattered from the surface of the intake valve 32 to the upstream side of the intake passage can be reduced even if the degree of the “blowback” increases in the future, and when the valve overlap period increases in the future. Temporary deterioration of the air-fuel ratio can be suppressed.

  In the first and second embodiments, the intake valve 32 is formed of an alloy containing Cr or the like. However, the heat resistance is lower than that of the alloy containing Cr or the like, and the cost is low. In some cases, it may be formed of another material that is lightweight (for example, an alloy containing Al or the like, a resin, or the like). In this case, when the lower limit value of the temperature range in which the other material is deformed or damaged by heat is lower than the lower limit value of the temperature range in which the deposit is generated, the upper limit value TVH is the value of the other material. The temperature should be lower than the lower limit of the temperature range in which deformation and breakage due to heat occur. Thereby, the cost reduction or weight reduction of an intake valve can be achieved.

  Further, in the first and second embodiments, the fuel adhesion residual amount fw is considered in order to determine the port injection amount fip. However, the fuel adhesion residual amount fw need not be considered. In this case, in FIG. 6 and FIG. 8, the value of the required port inflow fuel amount Fc calculated in step 526 is used as the port injection amount fip. As a result, the sum of the port injection amount fip and the in-cylinder injection amount fic always matches the basic fuel injection amount Fbase.

  In the first and second embodiments, the port injection ratio R (= fip / (fip + fic)) is adopted as the injection ratio. However, the in-cylinder injection ratio (fic / (fip + fic)) may be adopted. Further, the value “fip / fic” or the value “fic / fip” may be adopted as the injection ratio.

  In addition, in the first and second embodiments, the intake valve temperature acquisition value TV is estimated using a predetermined table or the like in steps 508 and 510 of FIG. 5 or FIG. The intake valve temperature acquisition value TV may be physically detected by an intake valve temperature sensor that detects 32 actual temperatures.

1 is a schematic configuration diagram of a system in which a fuel injection amount control device according to an embodiment of the present invention is applied to a spark ignition type multi-cylinder internal combustion engine. It is the figure which showed notionally the mode that the fuel injected from the port injection valve adhered to the surface of an intake valve. The amount of fuel injected from the port injection valve (port injection amount), the amount of fuel adhering and remaining on the surface of the intake valve (fuel adhering residual amount), and the amount of fuel flowing into the cylinder (necessary port) It is a figure for demonstrating the relationship with an inflow fuel amount. It is the graph which showed the relationship between a port injection ratio, in-cylinder intake air amount, and an intake valve temperature instantaneous value. 2 is a flowchart showing a first half of a program for determining a port injection amount and in-cylinder injection amount, and for executing port injection and in-cylinder injection, which is executed by the CPU shown in FIG. 1. 3 is a flowchart illustrating a second half of a program for determining a port injection amount and in-cylinder injection amount, and for executing port injection and in-cylinder injection, which is executed by the CPU shown in FIG. 1. The first half part of the program for determination of port injection amount and in-cylinder injection amount, and execution of port injection and in-cylinder injection executed by the CPU of the fuel injection amount control device according to the second embodiment of the present invention is shown. It is a flowchart. The latter half part of the program for determination of port injection amount and in-cylinder injection amount, and execution of port injection and in-cylinder injection which CPU of the fuel injection amount control apparatus which concerns on 2nd Embodiment of this invention performs is shown. It is a flowchart.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Spark ignition type multi-cylinder internal combustion engine, 25 ... Combustion chamber, 32 ... Intake valve, 39C ... In-cylinder injection valve, 39P ... Port injection valve, 41 ... Intake pipe, 70 ... Electric control device, 71 ... CPU

Claims (13)

Port injection means for injecting fuel into the intake passage upstream of the intake valve of the internal combustion engine;
In-cylinder injection means for injecting fuel into the combustion chamber;
Applied to an internal combustion engine with
An injection ratio that is a ratio of a port injection amount that is the amount of fuel injected from the port injection means and an in-cylinder injection amount that is the amount of fuel injected from the in-cylinder injection means is based on the operating state of the internal combustion engine. Injection ratio determining means for determining the basic injection ratio;
Injection amount determining means for determining the port injection amount and the in-cylinder injection amount based on the injection ratio determined by the injection ratio determining means;
A fuel injection amount control device for an internal combustion engine comprising:
Intake valve temperature acquisition means for acquiring the actual temperature of the intake valve as an intake valve temperature acquisition value;
Upper limit value determining means for determining an upper limit value of the temperature of the intake valve that should not exceed the temperature of the intake valve;
Further comprising
The injection ratio determining means includes
When the intake valve temperature acquisition value exceeds the upper limit value, the injection ratio is determined to be a value at which the ratio of the port injection amount is larger than the basic injection ratio instead of the basic injection ratio. A fuel injection amount control device for an internal combustion engine. Port injection means for injecting fuel into the intake passage upstream of the intake valve of the internal combustion engine;
In-cylinder injection means for injecting fuel into the combustion chamber;
Applied to an internal combustion engine with
An injection ratio that is a ratio of a port injection amount that is the amount of fuel injected from the port injection means and an in-cylinder injection amount that is the amount of fuel injected from the in-cylinder injection means is based on the operating state of the internal combustion engine. Injection ratio determining means for determining the basic injection ratio;
Injection amount determining means for determining the port injection amount and the in-cylinder injection amount based on the injection ratio determined by the injection ratio determining means;
A fuel injection amount control device for an internal combustion engine comprising:
Intake valve temperature acquisition means for acquiring the actual temperature of the intake valve as an intake valve temperature acquisition value;
Lower limit value determining means for determining a lower limit value of the temperature of the intake valve that should not be lower than the temperature of the intake valve;
Further comprising
The injection ratio determining means includes
When the intake valve temperature acquisition value is less than the lower limit value, the injection ratio is determined to be a value in which the ratio of the port injection amount is smaller than the basic injection ratio instead of the basic injection ratio. A fuel injection amount control device for an internal combustion engine. Port injection means for injecting fuel into the intake passage upstream of the intake valve of the internal combustion engine;
In-cylinder injection means for injecting fuel into the combustion chamber;
Applied to an internal combustion engine with
An injection ratio that is a ratio of a port injection amount that is the amount of fuel injected from the port injection means and an in-cylinder injection amount that is the amount of fuel injected from the in-cylinder injection means is based on the operating state of the internal combustion engine. Injection ratio determining means for determining the basic injection ratio;
Injection amount determining means for determining the port injection amount and the in-cylinder injection amount based on the injection ratio determined by the injection ratio determining means;
A fuel injection amount control device for an internal combustion engine comprising:
Intake valve temperature acquisition means for acquiring the actual temperature of the intake valve as an intake valve temperature acquisition value;
Upper limit value determining means for determining an upper limit value of the temperature of the intake valve that should not exceed the temperature of the intake valve;
Lower limit value determining means for determining a lower limit value of the temperature of the intake valve that should not be lower than the temperature of the intake valve;
Further comprising
The injection ratio determining means includes
When the intake valve temperature acquisition value exceeds the upper limit value, the injection ratio is determined to be a value at which the ratio of the port injection amount is larger than the basic injection ratio instead of the basic injection ratio, and the intake valve temperature When the acquired value is less than the lower limit value, an internal combustion engine configured to determine the injection ratio to a value in which the ratio of the port injection amount is smaller than the basic injection ratio instead of the basic injection ratio. Fuel injection amount control device. In the fuel injection amount control device for an internal combustion engine according to claim 1 or 3,
The upper limit determining means includes
A fuel injection amount control device for an internal combustion engine configured to determine an upper limit value of the temperature of the intake valve as a temperature value at which no deposit is generated on the surface of the intake valve. The fuel injection amount control device for an internal combustion engine according to claim 4,
The upper limit determining means includes
A fuel injection amount control device for an internal combustion engine configured to determine an upper limit value of the temperature of the intake valve based on at least an operation speed of the internal combustion engine and an air amount taken into the combustion chamber. In the fuel injection amount control device for an internal combustion engine according to claim 2 or 3,
The lower limit determining means includes
The lower limit value of the temperature of the intake valve is determined to be a temperature value at which the fuel adhesion residual amount, which is the amount of fuel adhering to and remaining on the surface of the intake valve due to injection by the port injection means, is equal to or less than a predetermined amount. A fuel injection amount control apparatus for an internal combustion engine configured to do the above. The fuel injection amount control device for an internal combustion engine according to claim 6,
The lower limit determining means includes
A fuel injection amount control device for an internal combustion engine configured to determine a lower limit value of the temperature of the intake valve based at least on an operating speed of the internal combustion engine. Port injection means for injecting fuel into the intake passage upstream of the intake valve of the internal combustion engine;
In-cylinder injection means for injecting fuel into the combustion chamber;
Applied to an internal combustion engine with
Intake valve temperature acquisition means for acquiring the actual temperature of the intake valve as an intake valve temperature acquisition value;
An intake valve temperature target value determining means for determining an intake valve temperature target value which is a target value of the temperature of the intake valve;
In-cylinder that is the amount of fuel that is injected from the port injection means and the amount of fuel that is injected from the in-cylinder injection means so that the intake valve temperature acquisition value approaches the intake valve temperature target value An injection ratio determining means for determining an injection ratio that is a ratio of an injection amount based on at least the intake valve temperature acquisition value and the intake valve temperature target value;
Injection amount determining means for determining the port injection amount and the in-cylinder injection amount based on the injection ratio determined by the injection ratio determining means;
A fuel injection amount control device for an internal combustion engine comprising: A fuel injection amount control device for an internal combustion engine according to claim 8,
An upper limit value determining means for determining an upper limit value of the temperature of the intake valve that should not exceed the temperature of the intake valve;
The intake valve temperature target value determining means includes:
A fuel injection amount control device for an internal combustion engine configured to determine the intake valve temperature target value based on the upper limit value. The fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 9,
The intake valve temperature acquisition means includes
A fuel injection amount control device for an internal combustion engine configured to acquire the intake valve temperature acquisition value based on at least an injection ratio determined by the injection ratio determination means. A fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 10,
A fuel adhesion residual amount estimating means for estimating a fuel adhesion residual amount that is an amount of fuel adhering to and remaining on the surface of the intake valve by injection by the port injection means;
The intake valve temperature acquisition means includes
A fuel injection amount control apparatus for an internal combustion engine configured to acquire the intake valve temperature acquisition value based on at least the fuel adhesion residual amount. The fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 11,
The internal combustion engine
The length of the valve overlap period, which is a period in which both the intake valve and the exhaust valve are open, is configured to be changeable according to the operating state of the internal combustion engine,
The injection ratio determining means includes
When the length of the valve overlap period is predicted to exceed a predetermined length in the future, the injection ratio is configured to be changed and determined to a value for increasing the temperature of the intake valve. A fuel injection amount control device for an internal combustion engine. The fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 12,
The internal combustion engine
The injection from the port injection means and the in-cylinder injection means is configured to be interruptable according to the operating state of the internal combustion engine,
The injection ratio determining means includes
An internal combustion engine configured to change / determine the injection ratio to a value for increasing the temperature of the intake valve when the interruption of injection from the port injection unit and the in-cylinder injection unit is released. Fuel injection amount control device.

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