JP2011058410A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To certainly inject fuel by an intake port injection valve and a cylinder injection valve even if a fuel injection system is deteriorated. <P>SOLUTION: The internal combustion engine 10 includes the intake port injection valve 30 and cylinder injection valve 32. An ECU 50 calculates cylinder premixture air mass Mg<SB>cyl</SB>as the total amount of an air-fuel mixture sucked into a cylinder and intake port injection mixture mass M<SB>cyl,lim</SB>involving only fuel injection by the intake port injection valve 30, based on cylinder inner pressure P<SB>cyl</SB>(θ) or the like. The actual cylinder injection quantity M<SB>d</SB>and intake port injection quantity M<SB>p</SB>are calculated based on these calculated values. Thereby, with respect to the intake port injection valve 30 and cylinder injection valve 32, a difference between the target value of the amount of fuel injected and the actual injection quantity is individually calculated. Accordingly, even if the fuel injection system is deteriorated, the fuel injection by the injection valves 30, 32 is always certainly performed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly, to a control device for an internal combustion engine provided with an intake port injection valve and a cylinder injection valve.

  As a conventional technique, for example, as disclosed in Japanese Patent Application Laid-Open No. 2006-118426, an intake port injection valve that injects fuel into an intake port of an internal combustion engine, and a cylinder that directly injects fuel into the cylinder A control device for an internal combustion engine including an internal injection valve is known. In this prior art, the injection amount sharing ratio between the intake port injection valve and the in-cylinder injection valve is calculated based on the operating state of the internal combustion engine. When the fuel injection amount of each injection valve is feedback-corrected based on the output of the air-fuel ratio sensor, the correction amount for each injection valve is set based on this injection amount sharing ratio and the like.

JP 2006-118426 A

  By the way, in the prior art mentioned above, it is set as the structure which each correct | amends the fuel injection quantity of an intake port injection valve and a cylinder injection valve based on the injection amount share rate etc. However, if the actual injection amount sharing rate deviates from the target due to deterioration of the fuel injection system, etc., even if each injection amount is corrected according to the injection amount sharing rate, the target injection amount sharing rate There is a problem that (fuel injection amount) cannot be realized.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide accurate fuel using an intake port injection valve and an in-cylinder injection valve even when the fuel injection system is deteriorated. An object of the present invention is to provide a control device for an internal combustion engine capable of performing injection.

The first invention includes an intake port injection valve that injects fuel into an intake port of an internal combustion engine;
An in-cylinder injection valve for injecting fuel into the cylinder of the internal combustion engine;
In-cylinder pressure detecting means for detecting in-cylinder pressure;
Temperature acquisition means for acquiring a temperature parameter corresponding to the temperature state in the cylinder;
When the intake valve of the internal combustion engine is closed by the fuel injected from the intake port injection valve and the in-cylinder injection valve, the total amount of the air-fuel mixture sucked into the cylinder at least when the intake valve is closed First gas mixture calculating means for calculating based on the in-cylinder pressure and the temperature parameter;
The in-cylinder pressure immediately before the fuel is injected from at least the in-cylinder injection valve is set to an intake port injection mixture amount that is the amount of the air-fuel mixture formed in the cylinder by only the fuel injected from the intake port injection valve. A second air-fuel ratio calculating means for calculating based on
In-cylinder injection amount calculating means for calculating an in-cylinder injection amount that is an injection amount of fuel actually injected from the in-cylinder injection valve based on a difference between the total amount of the air-fuel mixture and the intake port injection air-fuel mixture amount When,
An intake port injection amount for calculating an intake port injection amount, which is an injection amount of fuel actually injected from the intake port injection valve, based on the total amount of the mixture, the air-fuel ratio of the mixture, and the in-cylinder injection amount A calculation means;
It is characterized by providing.

According to a second aspect of the present invention, there is provided convergence determining means for determining whether or not the in-cylinder pressure has converged to a constant value during a period from when the intake valve is opened to immediately before fuel injection of the in-cylinder injection valve is performed. When,
In-cylinder pressure estimating means for estimating the in-cylinder pressure after convergence when the in-cylinder pressure does not converge to a constant value during the period,
The second air-fuel mixture amount calculating means calculates the intake port injection air-fuel mixture amount based on the convergence value when it is determined that the in-cylinder pressure has converged, and it is determined that the in-cylinder pressure does not converge. Sometimes, the intake port injection mixture amount is calculated based on the estimation result of the in-cylinder pressure estimation means.

  According to a third aspect of the invention, the temperature acquisition means is configured to change the temperature parameter based on a change in the in-cylinder pressure during a period from at least fuel injection of the in-cylinder injection valve to closing of the intake valve. The in-cylinder temperature that becomes

4th invention, The 1st learning means which learns the error of the said intake port injection amount based on the target value of the fuel injection amount by the said intake port injection valve, and the said intake port injection amount,
Second learning means for learning an error of the in-cylinder injection amount based on a target value of the fuel injection amount by the in-cylinder injection valve and the in-cylinder injection amount;
It is set as the structure provided with.

  According to the first invention, the first air-fuel ratio calculating means can calculate the total amount of the air-fuel mixture sucked into the cylinder, and the second air-fuel ratio calculating means is provided from the intake port injection valve. It is possible to calculate the intake port injection mixture amount in which only the injected fuel is involved. Thereby, the in-cylinder injection amount calculation means and the intake port injection amount calculation means can calculate the actual in-cylinder injection amount and the intake port injection amount, respectively. Therefore, the difference between the target value of the fuel injection amount and the actual injection amount can be calculated individually for each of the intake port injection valve and the in-cylinder injection valve, and the fuel injection of each injection valve is calculated based on the calculation result. It is possible to correct the amount, or to perform learning control of the fuel injection amount for each injection valve. As a result, even when deterioration or the like occurs in the fuel injection system, fuel injection by the intake port injection valve and the in-cylinder injection valve can always be performed accurately, and reliability and durability can be improved.

  According to the second invention, the convergence determination means determines whether or not the in-cylinder pressure has converged to a constant value during a period from when the intake valve is opened to immediately before fuel injection from the in-cylinder injection valve is performed. can do. Thus, the second air-fuel mixture amount calculating means calculates the intake port injection air-fuel mixture amount based on the convergence value of the in-cylinder pressure when the intake valve opening timing and the in-cylinder injection timing are separated. be able to. When the intake valve opening timing and the in-cylinder injection timing are close to each other, the intake port injection air-fuel mixture amount can be calculated based on the converged in-cylinder pressure estimated by the in-cylinder pressure estimating means. Therefore, even when the valve opening timing of the intake valve and the timing of in-cylinder injection vary, the in-cylinder pressure immediately before in-cylinder injection can be obtained by an appropriate method according to the interval between the two, and the intake port injection mixture amount Can always be calculated accurately.

  According to the third invention, the temperature acquisition means can estimate the in-cylinder temperature based at least on the change in the in-cylinder pressure from when the in-cylinder injection is performed until the intake valve is closed. Thus, the first and second mixture amount calculation means can accurately calculate the total amount of the mixture and the intake port injection mixture amount using the in-cylinder temperature close to the actual temperature state.

  According to the fourth aspect, the first and second learning means can learn these errors (deviations) based on the calculated actual in-cylinder injection amount and intake port injection amount. Therefore, even when deterioration or the like occurs in the fuel injection system, this deterioration can be absorbed by learning, and fuel injection can always be performed accurately.

It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. In Embodiment 1 of this invention, it is a flowchart which shows the control performed by ECU. In Embodiment 1 of this invention, it is a flowchart which shows the control performed by ECU. It is characteristic data which shows the relationship between the injection coefficient of a cylinder injection injection valve, an invalid injection time, and a fuel pressure. It is characteristic data which shows the relationship between the injection coefficient of an intake port injection valve, and an intake pipe negative pressure, and the relationship between an invalid injection time and a battery voltage. In Embodiment 2 of this invention, it is explanatory drawing which shows the change of the in-cylinder pressure during an intake stroke.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
The first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an overall configuration diagram for explaining a system configuration according to the first embodiment of the present invention. The system of the present embodiment includes a dual injection type internal combustion engine 10 on which, for example, two fuel injection valves are mounted. The cylinder 12 of the internal combustion engine 10 is provided with a combustion chamber 16 that expands and contracts by the reciprocating motion of the piston 14. The piston 14 is connected to a crankshaft 18 that is an output shaft of the internal combustion engine 10.

  The internal combustion engine 10 also includes an intake passage 20 that sucks intake air into the cylinder 12 and an exhaust passage 22 that discharges exhaust gas from the cylinder 12. The intake passage 20 is provided with an air flow meter 24 for detecting the amount of intake air and an electronically controlled throttle valve 26. The throttle valve 26 is driven by a throttle motor 28 based on the accelerator opening and the like to increase or decrease the intake air amount. Also, the cylinder 12 includes an intake port injection valve 30 that injects fuel into an intake port that is a portion in the vicinity of the cylinder in the intake passage 20, and an in-cylinder injection valve that directly injects fuel into the combustion chamber 16 (inside the cylinder). 32 is provided. Further, the cylinder 12 includes an ignition plug 34 that ignites the air-fuel mixture in the combustion chamber 16, an intake valve 36 that opens and closes the intake passage 20 relative to the combustion chamber 16, and an exhaust passage 22 that extends from the combustion chamber 16. An exhaust valve 38 that opens and closes is provided.

Further, the system of the present embodiment includes a sensor system including a crank angle sensor 40, an in-cylinder pressure sensor 42, a fuel pressure sensor 44, an intake pressure sensor 46, a water temperature sensor 48, and the like, and a control system for controlling the operating state of the internal combustion engine 10. An ECU (Electronic Control Unit) 50 is provided. The crank angle sensor 40 outputs a signal synchronized with the rotation of the crankshaft 18, and the ECU 50 detects the engine speed and the crank angle based on this output. The in-cylinder pressure sensor 42 detects the pressure in the combustion chamber 16 (in-cylinder pressure), and constitutes the in-cylinder pressure detecting means of the present embodiment. The ECU 50 has a function of detecting the in-cylinder pressure at an arbitrary crank angle θ by the in-cylinder pressure sensor 42 and storing the detection result as time-series data P _cyl (θ) of the in-cylinder pressure.

  The fuel pressure sensor 44 detects the pressure of fuel injected from the injection valves 30 and 32 (fuel pressure), the intake pressure sensor 46 detects the pressure of intake air (intake pipe pressure), and the water temperature sensor 48 detects the pressure of the internal combustion engine 10. The cooling water temperature is detected. In the present embodiment, the water temperature sensor 48 constitutes a temperature acquisition means, and the cooling water temperature is used as a temperature parameter corresponding to the temperature state in the cylinder. In addition to the air flow meter 24 and the sensors 40 to 48 described above, the sensor system includes various sensors (for example, an air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas) necessary for controlling the vehicle and the internal combustion engine. These are included and are connected to the input side of the ECU 50. On the other hand, on the output side of the ECU 50, various actuators including a throttle motor 28, injection valves 30, 32, a spark plug 34, and the like are connected.

  Then, the ECU 50 drives each actuator while detecting the operation state of the internal combustion engine by the sensor system. Specifically, the fuel injection amount, injection timing, ignition timing, and the like are set based on the output of the sensor system, and the actuator is driven in accordance with these settings. Further, the ECU 50 sets the fuel injection ratio by the injection valves 30 and 32 according to the operating state of the internal combustion engine. The ratio of the fuel injection amount by the injection valves 30 and 32 corresponds to the injection ratio.

[Features of Embodiment 1]
When deterioration or the like occurs in the fuel injection system, the fuel injection amount of the injection valves 30 and 32 may deviate from the target value of the injection amount set by the ECU 50. Therefore, the ECU 50 calculates the fuel injection amount actually injected from the intake port injection valve 30 and the in-cylinder injection valve 32, respectively, and based on the calculation result, the difference in the fuel injection amounts of the injection valves 30, 32 is calculated. learn. Hereinafter, these processes will be described.

(Calculation of in-cylinder premixed gas mass)
First, the ECU 50 calculates the in-cylinder premixed gas mass Mg _cyl which is the total amount (total mass) of the air-fuel mixture sucked into the cylinder when the intake valve 36 is closed. The in-cylinder premixed gas mass Mg _cyl is the total amount of the air-fuel mixture formed in the cylinder by the fuel injected from the injection valves 30 and 32, and more specifically, the amount of fuel injected from the intake port injection valve 30. This is the sum of the mass, the mass of fuel injected from the in-cylinder injection valve 32, and the mass of intake air sucked into the cylinder.

The in-cylinder premixed gas mass Mg _cyl is determined by the in-cylinder pressure P _cyl (θ _IVC ) detected by the in-cylinder pressure sensor 42 when the intake valve 36 is closed (hereinafter referred to as _IVC ), and the in-cylinder volume V at IVC. Using (θ _IVC ), the water temperature Tw detected by the water temperature sensor 48 during IVC, and the gas constant R, the following equation (1) is used. Here, θ _IVC is a crank angle corresponding to the closing timing of the intake valve 36. The in-cylinder volume V (θ _IVC ) at a specific crank angle θ _IVC can be calculated by storing the relationship between the crank angle θ and the in-cylinder volume V in the ECU 50 in advance.

The equation (1) is a modification of the gas equation of state. In this equation, the mass of vaporized fuel present in the mixture in the cylinder is reflected in the cylinder pressure P _cyl (θ _IVC ). . The water temperature Tw is used as a temperature parameter corresponding to the in-cylinder temperature.

(Calculation of in-cylinder air-fuel ratio)
Next, the ECU 50 calculates the in-cylinder air-fuel ratio abyf _cyl by a known method described in, for example, JP-A-2006-97588. As described in this publication, there is a certain correlation between the combustion time Tc from the start of combustion in the cylinder until the combustion substantially ends and the in-cylinder air-fuel ratio abyf _cyl. . Data indicating this correlation is stored in advance in the ECU 50 as map data or the like. The combustion time Tc is obtained as a difference between the previous ignition timing θ _SA and the crank angle θ _T at the end of combustion (that is, Tc = θ _T −θ _SA ). Further, the crank angle θ _T is calculated as a crank angle at which the theoretical heat generation amount Q _T theoretically obtained from the previous fuel injection time (fuel injection amount) is approximately equal to the assumed heat generation amount Q _A. Here, the assumed heat generation amount Q _A is calculated based on the change dP / dθ of the in-cylinder pressure P _cyl (θ) acquired from the previous ignition to the substantial end of combustion.

Therefore, the ECU 50 first calculates the theoretical heat generation amount Q _T based on the previous fuel injection time, and calculates the assumed heat generation amount Q _A based on the change dP / dθ of the in-cylinder pressure P _cyl (θ). Next, the combustion time Tc can be calculated based on the crank angle θ _{T at} which the heat generation amounts Q _T and Q _A are equal and the previous ignition timing θ _SA . The in-cylinder air-fuel ratio abyf _cyl can be calculated by referring to the map data based on the calculation result of the combustion time Tc.

(Calculation of in-cylinder fuel mass)
Next, the ECU 50 calculates the in-cylinder fuel mass Mf _cyl by the following equation (2) based on the in-cylinder premixed gas mass Mg _cyl and the in-cylinder air-fuel ratio abyf _cyl . The in-cylinder fuel mass Mf _cyl is the total amount of fuel sucked into the cylinder. More specifically, the in-cylinder fuel mass Mf _cyl is the mass of the fuel injected from the intake port injection valve 30 and the fuel injected from the in-cylinder injection valve 32. It is the sum of mass.

Mf _cyl = Mg _cyl / abyf _cyl (2)

(Calculation of intake port injection mixture mass)
Next, the ECU 50 calculates the intake port injection mixture mass _{Mcyl, lim} . The intake port injection mixture mass M _{cyl, lim} is the amount of the mixture formed in the cylinder only by the fuel injection (intake port injection) of the intake port injection valve 30 when the intake valve 36 is closed, that is, The amount (mass) of the air-fuel mixture excluding the influence of fuel injection (in-cylinder injection) of the in-cylinder injection valve 32. The intake port injection air-fuel mixture mass M _{cyl, lim} uses the in-cylinder pressure P _{cyl, lim} immediately before the in-cylinder injection is performed, the in-cylinder volume V (θ _IVC ), the water temperature Tw, and the gas constant R, It is calculated by the following equation (3). This calculation method uses the gas equation of state in substantially the same manner as described above.

The in-cylinder pressure P _{cyl, lim} immediately before the in-cylinder injection used in the equation (3) is obtained by the following procedure. First, the opening / closing operation of the intake valve 36 and the fuel injection occur in the order of intake port injection (PFI) → intake valve opening (IVO) → in-cylinder injection (DI) → intake valve closing (IVC). For this reason, the in-cylinder pressure before the in-cylinder injection is performed decreases transiently when the intake valve 36 is opened, and then converges to a constant value after a certain period of time has elapsed. Therefore, when the timing of IVO and in-cylinder injection is different, the in-cylinder pressure immediately before in-cylinder injection converges to a constant value, and this converged value is converted into in-cylinder pressure P _{cyl, lim} by the in-cylinder pressure sensor 42. Can be detected. On the other hand, when the timing of IVO and in-cylinder injection is close, the in-cylinder pressure is not stable immediately before in-cylinder injection, so it is necessary to estimate the in-cylinder pressure P _{cyl, lim} by another method. is there. Therefore, the ECU 50 first determines whether or not the in-cylinder pressure has converged to a constant value during the period from when the intake valve 36 is opened until immediately before in-cylinder injection, according to the following equation (4).

| P _cyl (θ _injd −Δθ) −P _cyl (θ _injd −2Δθ) | <ε (4)

In the equation (4), θ _injd represents a crank angle corresponding to the timing of in-cylinder injection, and Δθ represents a minute time (minute crank angle). Further, ε is a minute value that can be considered that the pressure difference is close to zero. That is, if the determination equation is satisfied, the cylinder injection immediately before the in-cylinder pressure _{P cyl} (θ injd -Δθ), which with even more even small time only before the cylinder pressure _{P cyl} (θ injd -2Δθ) but Since they are almost equal, it can be determined that the in-cylinder pressure immediately before in-cylinder injection has converged to a constant value. In this case, the in-cylinder pressure P _{cyl, lim} immediately before the in-cylinder injection used in the equation (3) is calculated by the following equation (5).

P _{cyl, lim} = P _cyl (θ _injd −Δθ) (5)

On the other hand, when the expression (4) is not established, the in-cylinder pressure does not converge to a constant value during the period from IVO to immediately before in-cylinder injection because the timing of IVO and in-cylinder injection is close. It is judged. In this case, the post-convergence in-cylinder pressure is estimated using, for example, a first-order lag model. Specifically, the constants k and τ of the first-order lag are calculated based on the in-cylinder pressure P _cyl (θ) (θ _IVO <θ <θ _injd ) from IVO to DI by the following equations (6) and (7). Based on the calculation result, the post-convergence in-cylinder pressure P _{cyl, lim} is obtained by the following equation (8). In these equations, θ _IVO and P _cyl (θ _IVO ) represent the crank angle corresponding to the opening timing of the intake valve 36 and the in-cylinder pressure at the crank angle.

P _{cyl, lim} = P _cyl (θ _IVO ) −k (8)

(Calculation of in-cylinder injection amount)
Next, the ECU 50 _{calculates the in-} cylinder injection amount M _d by the following equation (9) based on the in-cylinder pre-mixture mass Mg _cyl and the intake port injection mixture mass M _{cyl, lim} obtained by the above processing. calculate. The in-cylinder injection amount M _d is the injection amount (mass) of the fuel actually injected from the in-cylinder injection valve 32. According to the following equation (9), the in-cylinder pre-mixture mass Mg _cyl and the intake air mass contained in the intake port injection mixture mass M _{cyl, lim} are offset by subtraction, so the in-cylinder injection amount M _d Can be requested.

M _d = M _{g cyl} −M _{cyl, lim} (9)

(Calculation of intake port injection amount)
Next, the ECU 50 calculates the intake port injection amount M _p by the following equation (10) based on the in-cylinder fuel mass Mf _cyl and the in-cylinder injection amount M _d obtained by the above processing. The intake port injection amount M _p is the injection amount (mass) of the fuel actually injected from the intake port injection valve 30. Through the above processing, the actual intake port injection amount M _p and in-cylinder injection amount M _d can be acquired.

M _p = Mf _cyl −M _d (10)

(Learning control of fuel injection amount)
Next, the ECU 50 sets the fuel injection times τ _p and τ _d set for the injection valves 30 and 32 to realize the predetermined injection amounts Q _p and Q _d , and the actual injection amounts M _p and M _{d, respectively.} And learning control of the deviation of the fuel injection amount is performed. First, the fuel injection control as a premise will be described. In the fuel injection control, the entire fuel injection amount Q is determined based on the intake air amount and the like, and the fuel by the injection valves 30 and 32 is determined based on the operating state of the engine and the like. injection share ratio k _p of is set. The intake port injection amount Q _p and the in-cylinder injection amount Q _d are determined by the following equations (11) and (12) based on these parameters Q and k _p .

Q _p = k _p · Q (11)
Q _d = (1−k _p ) · Q (12)

The fuel injection times τ _p and τ _d of the injection valves 30 and 32 are set according to the following equations (13) and (14) based on the fuel injection amounts Q _p and Q _d . In these equations, a _p and a _d are injection coefficients corresponding to the time required for the injection valves 30 and 32 to perform unit amount fuel injection, and b _p and b _d are the injection valves 30 and 32. Is the invalid injection time that does not contribute to fuel injection.

τ _p = a _p · Q _p + b _p (13)
τ _d = a _d · Q _d + b _d (14)

Here, since the in-cylinder injection valve 32 injects fuel into a high-pressure cylinder with a high fuel pressure, the fuel injection amount is easily affected by fluctuations in fuel pressure. For this reason, the injection coefficient a _d and the invalid injection time b _{d of} the in-cylinder injection valve 32 are configured to be variably set according to the fuel pressure, as indicated by the solid line in FIG. FIG. 4 is characteristic data showing the relationship between the injection coefficient of the in-cylinder injection valve, the invalid injection time, and the fuel pressure. On the other hand, since the intake port injection valve 30 injects fuel into the low-pressure intake port with a relatively low fuel pressure, it is easily affected by fluctuations in the intake pipe pressure and battery voltage. For this reason, as indicated by a solid line in FIG. 5, the injection coefficient a _p of the intake port injection valve 30 is variably set according to the intake pipe pressure, and the invalid injection time b _p is variably set according to the battery voltage. It is the composition which becomes. FIG. 5 is characteristic data showing the relationship between the injection coefficient of the intake port injection valve and the intake pipe negative pressure, and the relationship between the invalid injection time and the battery voltage.

The above-described characteristic data shown in FIGS. 4 and 5 is stored in a rewritable state in a nonvolatile memory or the like mounted on the ECU 50. The ECU 50 refers to the characteristic data based on the fuel pressure, the intake pipe pressure, and the battery voltage when the injection amounts Q _p , Q _{d that} are target values are determined, and thereby sets the parameters a _p , a _d , b _p and _bd are determined. Based on these parameters and the injection amounts Q _p and Q _d , the fuel injection times τ _p and τ _d can be set according to the equations (13) and (14).

On the other hand, when the deterioration of the fuel injection system proceeds, a deviation occurs between the target injection values Q _p and Q _d and the actual injection amounts M _p and M _d . For this reason, in the learning control, the parameters a _p , a _d , b _p , b are set so that the actual injection amounts M _p , M _d obtained by the above-described processing become equal to the target injection amounts Q _p , Q _d. Change the value of _d (the stored value of the characteristic data). As a result, the characteristic data indicated by the solid line in FIGS. 4 and 5 is corrected to the state indicated by the dotted line by the learning control, so that the error (deviation) in the fuel injection amount due to deterioration with time can be absorbed by learning.

[Specific Processing for Realizing Embodiment 1]
2 and 3 are flowcharts showing the control executed by the ECU in the first embodiment of the present invention. The routines shown in these figures are repeatedly executed during operation of the internal combustion engine. First, in the routine shown in FIG. 2, the in-cylinder pressure P _cyl (θ) is acquired by the in-cylinder pressure sensor 42 (step 100). Further, the cylinder injection timing θ _injd and the valve closing timing θ _IVC of the intake valve 36 are acquired (steps 102 and 104). Further, the water temperature Tw at the time of IVC is acquired by the water temperature sensor 48, and the in-cylinder volume V (θ _IVC ) at the time of _IVC is calculated (steps 106 and 108).

Next, the in-cylinder premixed gas mass Mg _cyl is calculated by the above equation (1), and the in-cylinder air-fuel ratio abyf _cyl is calculated by the aforementioned processing (steps 110 and 112). Then, the in-cylinder fuel mass Mf _cyl is calculated by the equation (2) (step 114). Further, the valve opening timing θ _IVO of the intake valve 36 is acquired, and the in-cylinder pressure P _cyl (θ _IVO ) at the time of _IVO is acquired (steps 106 and 118).

Next, in step 120, whether or not the inequality of equation (4) holds, that is, whether the in-cylinder pressure has converged to a constant value during the period from when the intake valve 36 opens until immediately before in-cylinder injection. Determine whether or not. When this determination is established, as described above, the in-cylinder pressure P _{cyl, lim} immediately before in-cylinder injection is calculated by the above equation (5) _{, and the routine proceeds} to step 128 described later (step 122). On the other hand, when the determination in step 120 is not established, the first-order lag constants k and τ are calculated by the equations (6) and (7), and the in-cylinder pressure P after convergence is calculated by the equation (8) based on the calculation result. _{cyl, lim} is calculated (steps 124 and 126).

Next, in step 128, using the in-cylinder pressure P _{cyl, lim} calculated in step 122 or 126, etc., the intake port injection mixture mass M _{cyl, lim} is calculated by the above equation (3). Subsequently, the in-cylinder injection amount M _d is calculated by the equation (9), and the intake port injection amount M _p is calculated by the equation (10) (steps 130 and 132). With the above processing, the actual in-cylinder injection amount M _d and the intake port injection amount M _p can be obtained.

Next, in step 134, the fuel pressure is acquired by the fuel pressure sensor 44. Then, the above-described learning control is executed so that the actual in-cylinder injection amount M _d becomes equal to the target injection amount Q _{d at} the detected fuel pressure. In steps 138 and 140, the intake pipe pressure and the battery voltage are And get. Then, in the detected intake pipe pressure and battery voltage, two maps (two characteristic data shown in FIG. 5) related to PFI are set so that the actual intake port injection amount M _p becomes equal to the target injection amount Q _p . ) Is performed (step 142).

Then, based on the characteristic data of FIG. 4 and FIG. 5 in which learning control is performed, the fuel injection times τ _p and τ _d of the injection valves 30 and 32 are calculated, and the fuel is supplied to each injection valve based on the calculation result. An injection instruction is given (steps 144 and 146). Thereby, even when deterioration or the like occurs in the fuel injection system, fuel injection can be performed accurately.

As described above in detail, according to the present embodiment, only the in-cylinder premixed gas mass Mg _cyl which is the total amount of the air-fuel mixture sucked into the cylinder and the fuel injected from the intake port injection valve 30 are involved. The intake port injection mixture amount M _{cyl, lim} can be calculated, and the actual in-cylinder injection amount M _d and the intake port injection amount M _p can be calculated based on these calculated values. Therefore, for each of the intake port injection valve 30 and the in-cylinder injection valve 32, the difference between the target value of the fuel injection amount and the actual injection amount can be calculated individually. It is possible to correct the fuel injection amount, and to perform learning control of the fuel injection amount for each injection valve. As a result, even when the fuel injection system is deteriorated, fuel injection by the injection valves 30 and 32 can always be performed accurately, and reliability and durability can be improved. In addition, the calculation process of the fuel injection amount can be realized with a simple configuration using the in-cylinder pressure sensor 42.

Further, in the present embodiment, it is possible to determine whether or not the in-cylinder pressure has converged to a constant value during the period from when the intake valve is opened to immediately before in-cylinder injection, using the equation (4). Thereby, when the timing of IVO and DI is separated, the intake port injection mixture amount _{Mcyl, lim} can be calculated based on the convergence value of the in-cylinder pressure. Further, when the timings of IVO and DI are close to each other, the intake port injection mixture amount M _{cyl, lim} can be calculated based on the estimated post-convergence in-cylinder pressure. Therefore, even when the timing of IVO and DI fluctuates, the in-cylinder pressure immediately before in-cylinder injection can be acquired by an appropriate method according to the interval between the two, and the intake port injection mixture amount _{Mcyl, lim} can be always accurately determined. Can be calculated.

  In the first embodiment, in FIG. 2 and FIG. 3, step 110 shows a specific example of the first mixture amount calculation means, and steps 120 to 128 show a specific example of the second mixture amount calculation means. Show. Step 130 shows a specific example of the in-cylinder injection amount calculation means, and step 132 shows a specific example of the intake port injection amount calculation means. Step 120 shows a specific example of the convergence determination means, and steps 124 and 126 show a specific example of the in-cylinder pressure estimation means. Further, step 136 shows a specific example of the second learning means, and step 142 shows a specific example of the first learning means.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. Although the present embodiment employs the same system configuration (FIG. 1) as that of the first embodiment, the configuration differs from the first embodiment in the control contents described below. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 2]
In the present embodiment, the in-cylinder temperature T (θ _IVC ) at _IVC is estimated based on the change in the in-cylinder pressure at least during the period from when in-cylinder injection is performed to when the intake valve closes, and the estimation The value is used as a temperature parameter corresponding to the temperature state in the cylinder. Hereinafter, a method for calculating the in-cylinder temperature T (θ _IVC ) will be described.

(In-cylinder temperature estimation method)
FIG. 6 is an explanatory diagram showing a change in in-cylinder pressure during the intake stroke in the second embodiment of the present invention. As shown in FIG. 6, the in-cylinder temperature T (θ _IVC ) is calculated by the pressure P (θ _injd ), volume V (θ _injd ), mass M (θ _injd ) during in-cylinder injection (DI). ), Temperature T (θ _injd ), pressure P (θ _IVC ), volume V (θ _IVC ), mass M (θ _IVC ), and temperature T (θ _IVC ) when the intake valve is closed (IVC). First, when the gas equation of state is applied to each of DI and IVC, the following equations (15) and (16) are established. R is a gas constant.

P (θ _injd ) · V (θ _injd ) = M (θ _injd ) · R · T (θ _injd ) (15)
P (θ _IVC ) · V (θ _IVC ) = M (θ _IVC ) · R · T (θ _IVC ) (16)

  Moreover, when the state at the time of DI and the time of IVC is compared, the following equation (17) is established from the first law of thermodynamics. In this equation, κ is the specific heat ratio, and Q is the amount of heat obtained from the outside.

For the heat quantity Q, the following equation (18) is established. Here, α is a heat transfer coefficient, and T _cyl is the in-cylinder temperature.

Assuming that the in-cylinder temperature T _cyl changes linearly between DI and IVC, the following equation (19) is established. Then, by substituting the equation (19) into the equation (18), the following equation (20) can be obtained.

Further, when the equation (20) is integrated between θ _injd to θ _IVC , the following equation (21) can be obtained. By substituting the equation (21) into the equation (17), the following ( 22) Equation can be obtained.

Further, when the masses M (θ _IVC ) and M (θ _injd ) in the equation (22) are deleted using the _items (15) and (16), the equation (22) is expressed by the following equation (23): Can be rewritten as:

Further, since the temperature change is small between _DI and _IVC, it is assumed that T (θ _injd ) _≈T (θ _IVC ), and the temperature T (θ _injd ) in the equation (23) is set to T (θ _IVC ). The following equation (24) can be obtained by replacing the equations with The following equation (25) can be obtained by modifying this equation (24).

The parameter included in the right side of the equation (25) is a known value or a value that can be obtained from the known value. Therefore, according to the present embodiment, at least in the cylinder pressure (θ) between _DI and _IVC , the cylinder volumes V (θ _injd ) and V (θ _IVC ), and the water temperature Tw, The in-cylinder temperature T (θ _IVC ) can be accurately estimated. The above-described calculation process of the in-cylinder temperature T (θ _IVC ) constitutes a temperature acquisition unit in the present embodiment.

[Specific Processing for Realizing Embodiment 2]
Next, a case where the in-cylinder temperature T (θ _IVC ) is applied to the first embodiment will be described. In this case, first, in step 108 in FIG. 2, after calculating the in-cylinder volume V (θ _IVC ) at _IVC , the in-cylinder temperature T (θ _IVC ) is estimated by the above-described calculation process. In steps 110 and 128 in FIGS. 2 and 3, when calculating the in-cylinder premixed gas mass Mg _cyl and the intake port injection mixed gas mass _{Mcyl, lim} , in the above formulas (1) and (3) In-cylinder temperature T (θ _IVC ) is used instead of the water temperature Tw. Specifically, the following equations (26) and (27) are obtained.

Therefore, according to the present embodiment, the in-cylinder _premixture mass Mg _cyl and the intake port injection mixture mass _{Mcyl, lim} are accurately determined using the in-cylinder temperature T (θ _IVC ) close to the actual temperature state. The accuracy of learning control can be improved.

In the first embodiment, the case where the fuel injection amount learning control is performed based on the calculated in-cylinder injection amount M _d and the intake port injection amount M _p has been described as an example. However, the present invention is not always necessary to perform the learning control, for example on the basis of the in-cylinder injection quantity M _d and intake port injection quantity M _p, may be configured to correct the injection quantity in the next fuel injection.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Cylinder 14 Piston 16 Combustion chamber 18 Crankshaft 20 Intake passage 22 Exhaust passage 24 Air flow meter 26 Throttle valve 28 Throttle motor 30 Intake port injection valve 32 In-cylinder injection valve 34 Spark plug 36 Intake valve 38 Exhaust valve 40 Crank angle Sensor 42 In-cylinder pressure sensor (in-cylinder pressure detection means)
44 Fuel pressure sensor 46 Intake pressure sensor 48 Water temperature sensor (temperature acquisition means)
50 ECU
Mg _cyl Pre-mixed gas mass in cylinder (total amount of mixed gas)
M _{cyl, lim} Intake port injection mixture amount M _{d In-} cylinder injection amount M _p Intake port injection amount

Claims (4)

An intake port injection valve for injecting fuel into the intake port of the internal combustion engine;
An in-cylinder injection valve for injecting fuel into the cylinder of the internal combustion engine;
In-cylinder pressure detecting means for detecting in-cylinder pressure;
Temperature acquisition means for acquiring a temperature parameter corresponding to the temperature state in the cylinder;
When the intake valve of the internal combustion engine is closed by the fuel injected from the intake port injection valve and the in-cylinder injection valve, the total amount of the air-fuel mixture sucked into the cylinder at least when the intake valve is closed First gas mixture calculating means for calculating based on the in-cylinder pressure and the temperature parameter;
The in-cylinder pressure immediately before the fuel is injected from at least the in-cylinder injection valve is set to an intake port injection mixture amount that is the amount of the air-fuel mixture formed in the cylinder by only the fuel injected from the intake port injection valve. A second air-fuel ratio calculating means for calculating based on
In-cylinder injection amount calculating means for calculating an in-cylinder injection amount that is an injection amount of fuel actually injected from the in-cylinder injection valve based on a difference between the total amount of the air-fuel mixture and the intake port injection air-fuel mixture amount When,
An intake port injection amount for calculating an intake port injection amount, which is an injection amount of fuel actually injected from the intake port injection valve, based on the total amount of the mixture, the air-fuel ratio of the mixture, and the in-cylinder injection amount A calculation means;
A control device for an internal combustion engine, comprising: Convergence determining means for determining whether or not the in-cylinder pressure has converged to a constant value during a period from when the intake valve is opened to immediately before fuel injection of the in-cylinder injection valve is performed;
In-cylinder pressure estimating means for estimating the in-cylinder pressure after convergence when the in-cylinder pressure does not converge to a constant value during the period,
The second air-fuel mixture amount calculating means calculates the intake port injection air-fuel mixture amount based on the convergence value when it is determined that the in-cylinder pressure has converged, and it is determined that the in-cylinder pressure does not converge. 2. The control device for an internal combustion engine according to claim 1, wherein the control unit is configured to calculate the intake port injection air-fuel mixture amount based on an estimation result of the in-cylinder pressure estimation means.   The temperature acquisition means estimates an in-cylinder temperature serving as the temperature parameter based on a change in the in-cylinder pressure in a period from at least fuel injection of the in-cylinder injection valve to closing of the intake valve. The control device for an internal combustion engine according to claim 1 or 2, wherein the control device is configured as described above. First learning means for learning an error of the intake port injection amount based on a target value of the fuel injection amount by the intake port injection valve and the intake port injection amount;
Second learning means for learning an error of the in-cylinder injection amount based on a target value of the fuel injection amount by the in-cylinder injection valve and the in-cylinder injection amount;
The control apparatus for an internal combustion engine according to any one of claims 1 to 3, further comprising:

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