JP2019218934A - Control device of internal combustion engine - Google Patents

Abstract

To provide a control device of an internal combustion engine capable of restraining PN.SOLUTION: A CPU 52 selects any of multi-injection processing for injecting a required injection amount in one combustion cycle while separating it into an injection amount of intake asynchronous injection for injecting fuel before an intake valve 18 is opened and an injection amount of intake synchronous injection for injecting fuel in synchronous with a valve opening period of an intake valve 18, and single-injection processing for injecting the fuel only by the intake asynchronous injection, at the time of restarting an internal combustion engine 10. The CPU 52 selects the single-injection processing when water temperature THW is defined temperature or higher and an integration value of an air amount after starting initial cranking is a predetermined value or more, at the time of restarting the internal combustion engine 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an internal combustion engine applied to an internal combustion engine including a port injection valve that injects fuel into an intake passage.

  For example, Patent Document 1 below discloses a control device that injects an amount of fuel calculated based on a water temperature at the time of starting an internal combustion engine. Here, when the water temperature is low, the injection amount is increased as compared with the case where the water temperature is high (paragraph "0002").

JP-A-5-214986

  By the way, when the injection amount is increased when the water temperature is low as described above, the amount of fuel adhering to the intake system of the internal combustion engine such as the intake passage and the intake valve increases, so that the number of particulate matter (PM) PN) may increase.

Hereinafter, means for solving the above-mentioned problems and the effects thereof will be described.
1. The present invention is applied to an internal combustion engine having a port injection valve for injecting fuel into an intake passage, and injecting a required amount of fuel calculated without depending on a detected value of an intake air amount at the time of starting the internal combustion engine. A multi-injection process for executing intake synchronous injection for injecting fuel in synchronization with a valve opening period of the fuel injection and asynchronous intake injection for injecting fuel at a timing advanced from the intake synchronous injection; A selection process for selecting one of a single injection process of injecting the fuel by the intake asynchronous injection, and an operation process of operating the port injection valve to execute the process selected by the selection process. In the selection process, when the temperature of the cooling water of the internal combustion engine is equal to or higher than a specified temperature, the single injection process is selected, and when the temperature of the cooling water is lower than the specified temperature, The control apparatus for an internal combustion engine comprising a process of selecting a multi-injection process.

  When all the fuel of the required injection amount is injected by the intake asynchronous injection when the temperature of the intake system of the internal combustion engine is low, the number (PN) of particulate matter (PM) in the exhaust may increase. It is presumed that this is because the amount of fuel adhering to the intake system increases and a part of the adhering fuel flows into the combustion chamber as droplets due to shearing of the fuel, thereby generating PM. Therefore, in the above configuration, when the temperature of the cooling water having a positive correlation with the temperature of the intake system is lower than the specified temperature, a part of the required injection amount is injected by the synchronous injection to reduce the asynchronous injection amount, and as a result, Reduce the amount of fuel adhering to the intake system. This can prevent the fuel from flowing into the combustion chamber as droplets due to the shearing of the attached fuel.

  2. When the internal combustion engine is intermittently driven, even when the temperature of the cooling water of the internal combustion engine is equal to or higher than a predetermined temperature, the selection process is performed when the integrated value of the amount of air taken into the intake passage is a predetermined value. Until the above, the control device for an internal combustion engine according to the above 1 includes a process for selecting the multi-injection process.

  Since the integrated value has a positive correlation with the combustion energy in the combustion chamber, the temperature of the intake system tends to be higher when the integrated value is large than when it is small. In particular, since the intake valve in the intake system directly receives heat generated in the combustion chamber, the temperature of the intake valve can be accurately grasped by using the integrated value. Therefore, by performing the multi-injection processing until the integrated value becomes equal to or more than the predetermined value as in the above configuration, the specified temperature can be set to a lower value compared to a case where such setting is not performed.

  3. Performing an asynchronous injection amount calculation process for calculating an asynchronous injection amount that is an injection amount of the intake asynchronous injection in the multi-injection process, wherein the asynchronous injection amount calculation process increases the asynchronous injection amount when the temperature is low. 3. The method according to claim 1, further comprising: a process of calculating a value larger than a case, and a process of calculating the asynchronous injection amount to a smaller value when the elapsed time from the stop of the internal combustion engine to the start thereof is shorter than when the elapsed time is longer. Of the internal combustion engine.

  When the temperature of the intake system is low, the amount of the fuel injected from the port injection valve that is not subject to combustion in the combustion chamber and remains in the intake system is greater than when the temperature is high. Therefore, in the above configuration, when the temperature of the cooling water having a positive correlation with the temperature of the intake system is low, the asynchronous injection amount is calculated to be a larger value than when the temperature of the cooling water is high. Excessive leaning of the fuel ratio can be suppressed.

  By the way, when the stop time of the internal combustion engine is shorter than the time required for the internal combustion engine and its surroundings to be in thermal equilibrium, the temperature of the intake system such as the intake valve does not match the temperature of the cooling water. Tend. Further, when the stop time is shorter than the required time, the temperature of the intake system tends to be higher when the stop time is shorter than when it is longer. Therefore, when calculating the asynchronous injection amount without considering the stop time even when the stop time is short, the asynchronous injection amount becomes excessive, and the air-fuel ratio in the combustion chamber may become excessively rich. Thus, in the above configuration, when the stop time is short, the asynchronous injection amount is set to a smaller value than when the stop time is long, so that the air-fuel ratio of the air-fuel mixture to be burned in the combustion chamber can be suppressed from becoming excessively rich.

  4. When the internal combustion engine is intermittently driven, the accumulated time during which the internal combustion engine is stopped is reduced when the integrated value of the amount of air drawn into the intake passage after the start of the internal combustion engine is large. A stop time calculation process for calculating an intermittent integration stop time reduced and corrected by a reduction correction ratio larger than the asynchronous injection amount calculation process, wherein the asynchronous injection amount calculation process is longer when the intermittent integration stop time is longer than when the intermittent integration stop time is shorter. 4. The control device for an internal combustion engine according to the above item 3, wherein the control device includes a process of calculating a large value.

  When the internal combustion engine is intermittently driven, the time required for the internal combustion engine and its surroundings to be in thermal equilibrium when the internal combustion engine is stopped has a positive correlation with the total amount of combustion energy when the internal combustion engine is driven. . Therefore, in the above configuration, by setting the intermittent integration stop time to a value obtained by reducing the cumulative time by the integrated value of the air amount, the intermittent integration stop time can be used as a parameter that accurately represents the temperature of the intake system. it can. For this reason, by calculating the asynchronous injection amount based on the intermittent integration stop time, it is possible to preferably suppress the air-fuel ratio of the air-fuel mixture to be burned from being excessively deviated from the target in the combustion chamber.

  5. The control device for an internal combustion engine according to the above item 3 or 4, wherein the asynchronous injection amount calculation process includes a process of calculating the asynchronous injection amount to a larger value when the atmospheric pressure is higher than when the atmospheric pressure is lower.

  When the atmospheric pressure is high, the pressure in the intake passage at the time of starting is higher than when the atmospheric pressure is low, so that the amount of air charged into the combustion chamber increases. Therefore, in the above configuration, the asynchronous injection amount is set to a larger value when the atmospheric pressure is high than when it is low, so that the air-fuel ratio of the air-fuel mixture to be burned in the combustion chamber even when the atmospheric pressure is high. Can be suppressed from becoming excessively lean.

  6. The internal combustion engine includes a throttle valve, and the non-synchronous injection amount calculation processing is performed when the start of the internal combustion engine is a restart of the internal combustion engine, when the intake pressure is low, as compared to when the intake pressure is high. 6. The control device for an internal combustion engine according to the above item 5, including a process of calculating the injection amount to a small value.

  Immediately after the internal combustion engine is stopped, the pressure in the intake passage tends to be lower than the atmospheric pressure, and the pressure in the intake passage tends to converge to the atmospheric pressure over time. Therefore, at the time of restart, the pressure in the intake passage may still be lower than the atmospheric pressure, and in that case, the vapor pressure of the fuel in the intake passage may be lower than when the pressure is the atmospheric pressure. Therefore, the fuel is easily atomized. Therefore, in that case, the fuel injected from the port injection valve remains in the intake system without flowing into the combustion chamber as compared with the case where the pressure in the intake passage converges to the atmospheric pressure immediately before the restart. The amount of fuel tends to be low. Therefore, in the above configuration, when the intake pressure is low, the asynchronous injection amount is calculated to be a smaller value than when the intake pressure is high, so that the air-fuel ratio of the air-fuel mixture to be burned in the combustion chamber at the time of restart becomes excessively rich. Can be suppressed.

  7. Any one of the above 4 to 6 which executes a synchronous injection amount calculation process of calculating a synchronous injection amount which is an injection amount of the intake synchronous injection based on the temperature without depending on an elapsed time from a stop of the internal combustion engine to a start thereof. A control device for an internal combustion engine according to any one of the above.

  Since the elapsed time from the stop of the internal combustion engine to the start thereof has a negative correlation with the temperature of the intake system, the elapsed time is attached to the intake system without flowing into the combustion chamber of the intake asynchronous injection amount. It has a positive correlation with the amount that stays. On the other hand, the correlation between the elapsed time and the amount of the synchronous injection amount that remains attached to the intake system without flowing into the combustion chamber is that the elapsed time and the asynchronous injection amount of the intake air flow into the combustion chamber. It is not as strong as the correlation with the amount that remains attached to the intake system. For this reason, in the above configuration, the asynchronous injection amount is determined according to the elapsed time, while the synchronous injection amount is determined regardless of the elapsed time, so that the fuel that adheres to the intake system without flowing into the combustion chamber and remains there With respect to the intake asynchronous injection in which the amount is remarkable, the injection amount can be controlled according to the amount of fuel remaining in the intake system.

FIG. 1 is a diagram showing a control device and an internal combustion engine according to a first embodiment. (A) And (b) is a figure showing the ejection pattern concerning the embodiment. 5 is a flowchart showing a procedure of a process executed by the control device according to the embodiment. (A) shows the relationship between the atmospheric pressure and the pressure correction coefficient, and (b) shows the relationship between the intake pressure and the pressure correction coefficient. The figure which shows the relationship between a stop time and a stop time correction coefficient. 5 is a flowchart showing a procedure of a process executed by the control device according to the embodiment. 9 is a flowchart showing a procedure of a process executed by a control device according to the second embodiment.

<First embodiment>
Hereinafter, a first embodiment of a control device for an internal combustion engine will be described with reference to the drawings.

  In the intake passage 12 of the internal combustion engine 10 shown in FIG. 1, a throttle valve 14 and a port injection valve 16 are provided in order from the upstream side. The air sucked into the intake passage 12 and the fuel injected from the port injection valve 16 flow into the combustion chamber 24 defined by the cylinder 20 and the piston 22 with the opening of the intake valve 18. In the combustion chamber 24, the mixture of fuel and air is provided for combustion by spark discharge of the ignition device 26. Then, combustion energy generated by the combustion is converted into rotational energy of the crankshaft 28 via the piston 22. The air-fuel mixture supplied to the combustion is discharged to the exhaust passage 32 as exhaust gas when the exhaust valve 30 is opened. A catalyst 34 is provided in the exhaust passage 32.

  The rotational power of the crankshaft 28 is transmitted to an intake camshaft 40 and an exhaust camshaft 42 via a timing chain 38. In this embodiment, the power of the timing chain 38 is transmitted to the intake-side camshaft 40 via the intake-side valve timing adjusting device 44. The intake valve timing adjustment device 44 is an actuator that adjusts the valve opening timing of the intake valve 18 by adjusting the rotational phase difference between the crankshaft 28 and the intake camshaft 40.

  A motor generator 36 that generates thrust of the vehicle together with the internal combustion engine 10 is mechanically connected to the crankshaft 28. That is, the vehicle according to the present embodiment is a hybrid vehicle that uses the internal combustion engine 10 and the motor generator 36 as a vehicle thrust generating device.

  The control device 50 controls the internal combustion engine 10 and controls the control amount (torque, exhaust component ratio, etc.) of the throttle valve 14, the port injection valve 16, the ignition device 26, the intake-side valve timing adjustment. The operation unit of the internal combustion engine 10 such as the device 44 is operated. At this time, the control device 50 controls the throttle valve 14 of the output signal Scr of the crank angle sensor 60, the intake air amount Ga detected by the air flow meter 62, and the pressure in the intake passage 12 detected by the intake pressure sensor 64. Is referred to as the pressure on the downstream side (intake pressure Pin). The control device 50 also controls the air-fuel ratio Af detected by the air-fuel ratio sensor 66, the output signal Sca of the intake-side cam angle sensor 68, the temperature of the cooling water of the internal combustion engine 10 detected by the water temperature sensor 70 (water temperature THW), Reference is made to the atmospheric pressure Pa detected by the atmospheric pressure sensor 72.

  The control device 50 controls the motor generator 36 to be controlled, and controls the control amount (torque, rotation speed, and the like). FIG. 1 illustrates operation signals MS1 to MS5 for operating the throttle valve 14, the port injection valve 16, the ignition device 26, the motor generator 36, and the intake-side valve timing adjustment device 44, respectively.

  The control device 50 includes a CPU 52, a ROM 54, and a power supply circuit 56 that supplies power to each part in the control device 50. The CPU 52 executes a program stored in the ROM 54 to control the control amount. Execute.

In the present embodiment, the fuel injection process includes two processes, a process illustrated in FIG. 2A and a process illustrated in FIG. 2B.
FIG. 2A shows two types of intake synchronous injection, in which fuel is injected in synchronization with the opening period of the intake valve 18, and intake asynchronous injection in which fuel is injected at a more advanced timing than the intake synchronous injection. This is a multi-injection process for executing fuel injection. More specifically, in the intake synchronous injection, a period during which the fuel injected from the port injection valve 16 reaches the position before the opening of the intake valve 18 (the downstream end of the intake port, in other words, the entrance to the combustion chamber 24) is provided. The fuel is injected so as to fall within the opening period of the intake valve 18. Here, the start point of the “arrival period” is the timing at which the fuel injected at the earliest timing among the fuels injected from the port injection valve 16 reaches the position before the valve is opened, and the end point is the port injection timing. This is the timing at which the fuel injected at the latest timing among the fuels injected from the valve 16 reaches the position before the valve is opened. On the other hand, the intake asynchronous injection is to inject fuel so that the fuel injected from the port injection valve 16 reaches the intake valve 18 before the intake valve 18 opens. In other words, the intake asynchronous injection is an injection in which the fuel injected from the port injection valve 16 stays in the intake passage 12 until the intake valve 18 opens, and flows into the combustion chamber 24 after opening. is there. Note that, in the present embodiment, the intake asynchronous injection is such that the fuel injected from the port injection valve 16 reaches the position before the intake valve 18 opens before the intake valve 18 closes. Shall be.

FIG. 2B shows a single injection process in which only the intake asynchronous injection is performed.
In the present embodiment, the multi-injection process is executed with the aim of reducing the number (PN) of particulate matter (PM) in the exhaust gas. That is, when the temperature of the intake system of the internal combustion engine 10 such as the intake passage 12 and the intake valve 18 is low to some extent, the PN tends to increase when the single injection process is executed. This is because when the temperature of the intake system is low, the required injection amount, which is the amount of fuel to be injected from the port injection valve 16 in one combustion cycle, becomes a large value, and as a result, the amount of fuel adhering to the intake system increases. It is thought that it is caused. More specifically, it is presumed that when the amount of fuel attached to the intake system increases to a certain extent, a part of the attached fuel flows into the combustion chamber 24 as droplets due to the shearing of the attached fuel. Therefore, in the present embodiment, by injecting a part of the required injection amount by the intake synchronous injection, even if the required injection amount is large, the amount of fuel adhering to the intake system is reduced in spite of the large required injection amount. Thus, the PN is reduced.

  FIG. 3 shows a processing procedure at the time of starting the internal combustion engine 10 according to the present embodiment. The process shown in FIG. 3 is realized by CPU 52 repeatedly executing a program stored in ROM 54 at, for example, a predetermined cycle. In the following, the step number of each process is represented by a number prefixed with “S”.

  In the series of processes shown in FIG. 3, the CPU 52 first determines whether or not it is within a predetermined period after the start of cranking (S10). Here, the predetermined period means that the amount of air to be charged into the combustion chamber 24 cannot be accurately grasped by the intake air amount Ga detected by the air flow meter 62, and the required injection amount is accurately determined based on the intake air amount Ga. The period cannot be calculated well. When determining that it is within the predetermined period (S10: YES), the CPU 52 determines whether there is a request for the multi-injection process (S12). When determining that there is a request for the multi-injection process (S12: YES), the CPU 52 determines the asynchronous base injection amount Qnsb, which is the base value of the intake asynchronous injection amount, based on the water temperature THW and the number of injections after the start of cranking. Is calculated (S14). Here, the CPU 52 calculates the asynchronous base injection amount Qnsb to a larger value when the water temperature THW is low than when it is high. In this process, the CPU 52 performs a map calculation of the asynchronous base injection amount Qnsb in a state where map data having the water temperature THW and the number of injections as input variables and the asynchronous base injection amount Qnsb as an output variable is stored in the ROM 54 in advance. realizable. Here, the map data is a set of discrete values of the input variables and values of the output variables corresponding to the values of the input variables. The map operation is performed, for example, when the value of the input variable matches any of the input variables of the map data, and the value of the output variable of the corresponding map data is used as the calculation result. What is necessary is just to make the value obtained by interpolation of the value of several output variables contained in data into a calculation result.

  Next, the CPU 52 determines whether or not it is time to restart the internal combustion engine 10 (S16). Here, the restart is the second or subsequent start of the internal combustion engine 10 during a period from when the start switch of the vehicle is turned on to when it is turned off. The start switch is a switch for enabling the vehicle to run when the user releases the brake and operates the accelerator. When determining that it is not the time of restart (S16: NO), the CPU 52 calculates a pressure correction coefficient Ka that is a correction coefficient of the asynchronous base injection amount Qnsb according to the atmospheric pressure Pa (S18). Specifically, as shown in FIG. 4A, the pressure correction coefficient Ka is calculated to be larger when the atmospheric pressure Pa is high than when it is low. This is because when the atmospheric pressure Pa is high, the pressure in the intake passage 12 at the time of starting is higher than when the atmospheric pressure Pa is low, so that the amount of air charged into the combustion chamber 24 is increased. Things. When the amount of air charged into the combustion chamber 24 is large due to the high atmospheric pressure Pa, the asynchronous injection amount Qns, which is the injection amount of the intake asynchronous injection, is set to a larger value than when the amount of air charged into the combustion chamber 24 is small. Even if Pa is high, the air-fuel ratio of the air-fuel mixture to be burned in the combustion chamber 24 is prevented from being excessively lean. Note that this processing can be realized by the CPU 52 performing a map calculation of the pressure correction coefficient Ka in a state where map data using the atmospheric pressure Pa as an input variable and the pressure correction coefficient Ka as an output variable is stored in the ROM 54 in advance.

  Referring back to FIG. 3, when determining that it is time to restart (S16: YES), the CPU 52 variably sets the pressure correction coefficient Ka according to the atmospheric pressure Pa and the intake pressure Pin (S20). Here, the CPU 52 calculates the pressure correction coefficient Ka to a larger value when the atmospheric pressure Pa is high than when it is low, as in the case where the restart is not performed. Further, as shown in FIG. 4B, the CPU 52 calculates the pressure correction coefficient Ka to be smaller when the intake pressure Pin is low than when it is high. This is because at the time of restart, the pressure in the intake passage 12 may still be lower than the atmospheric pressure Pa, and in this case, the fuel vapor This is because the fuel is easily atomized because the pressure is low. That is, when the fuel is easily atomized, the fuel injected from the port injection valve 16 flows into the combustion chamber 24 as compared with the case where the pressure in the intake passage 12 converges to the atmospheric pressure immediately before the restart. And the amount of fuel remaining in the intake system tends to decrease. Therefore, if the same amount of fuel is injected when the intake pressure Pin is low and when it is high, the air-fuel ratio of the air-fuel mixture to be burned in the combustion chamber 24 may be excessively rich. In this process, the CPU 52 performs a map calculation of the pressure correction coefficient Ka with the map data in which the atmospheric pressure Pa and the intake pressure Pin are input variables and the pressure correction coefficient Ka is an output variable stored in the ROM 54 in advance. Can be realized by

  Referring back to FIG. 3, when the process of S20 is completed, the CPU 52 determines the amount of the asynchronous base injection amount Qnsb based on the stop time Tstp of the internal combustion engine 10 that is the elapsed time from the previous stop of the internal combustion engine 10 to the current start. The stop time correction coefficient Ks is calculated (S22). More specifically, as shown in FIG. 5, the CPU 52 calculates the stop time correction coefficient Ks to be larger when the stop time Tstp is longer than when the stop time Tstp is shorter. This processing can be realized by performing a map calculation of the stop time correction coefficient Ks by the CPU 52 in a state where map data using the stop time Tstp as an input variable and the stop time correction coefficient Ks as an output variable is stored in the ROM 54 in advance.

  Returning to FIG. 3, when the processing of S22 or S18 is completed, the CPU 52 substitutes a value obtained by multiplying the asynchronous base injection amount Qnsb by the pressure correction coefficient Ka and the stop time correction coefficient Ks for the asynchronous injection amount Qns (S24). ).

  Next, the CPU 52 determines whether or not it is time to restart (S26). Then, when determining that it is not the time of restart (S26: NO), the CPU 52 calculates the synchronous injection amount Qs, which is the injection amount of the intake synchronous injection, based on the water temperature THW and the atmospheric pressure Pa (S28). On the other hand, when determining that it is time to restart (S26: YES), the CPU 52 calculates the synchronous injection amount Qs based on the water temperature THW, the atmospheric pressure Pa, and the intake pressure Pin (S30). Note that the reason for using the water temperature THW, the atmospheric pressure Pa, and the intake pressure Pin in the processing of S28 and S30 is the same as in the case of calculating the asynchronous injection amount Qns.

  Since the sum of the asynchronous injection amount Qns and the synchronous injection amount Qs is the required injection amount in one combustion cycle, the processing of S14 to S30 determines the required injection amount by the asynchronous injection amount Qns and the synchronous injection amount Qs. Can be regarded as the process of dividing into

  When the processes in S28 and S30 are completed, the CPU 52 performs the intake synchronization based on the water temperature THW, the rotational speed NE, and the intake phase difference DIN which is the phase difference between the rotational angle of the crankshaft 28 and the rotational angle of the intake camshaft 40. The injection start timing Is of the injection is calculated (S32). The CPU 52 performs a map calculation of the injection start timing Is with the map data in which the water temperature THW, the rotation speed NE, and the intake phase difference DIN are input variables, and the injection start timing Is is an output variable, stored in the ROM 54 in advance. Processing. At the time of starting, the intake phase difference DIN may be a fixed value. Even in such a case, it is effective to calculate the injection start timing Is according to the intake phase difference DIN when the fixed value of the intake phase difference DIN at the time of starting differs depending on the vehicle.

  Next, the CPU 52 calculates the injection start timing Ins of the intake asynchronous injection such that the intake asynchronous injection ends at least a predetermined time before the injection start timing Is (S34). Here, the predetermined time is determined by the structure of the port injection valve 16, and is used to avoid the start of the injection on the retard side before the end of the injection on the advance side among the fuel injections adjacent in time series. It is time. The CPU 52 causes the port injection valve 16 to inject the asynchronous injection amount Qns of fuel from the port injection valve 16 when the injection start time Ins is reached, and to inject the synchronous injection amount Qs of fuel from the port injection valve 16 when the injection start time Is is reached. The operation signal MS2 is output to the port 16 to operate the port injection valve 16 (S36).

  On the other hand, if the CPU 52 determines that there is no request to execute the multi-injection process (S12: NO), the CPU 52 is required for one combustion cycle based on the water temperature THW, the number of injections after the start of cranking, and the stop time Tstp. The required injection amount Qd, which is the injection amount, is calculated (S38). Next, the CPU 52 sets the injection start timing Isin (S40). Then, when the injection start timing Isin comes, the CPU 52 outputs the operation signal MS2 to the port injection valve 16 to inject the fuel of the required injection amount Qd and operates the port injection valve 16 (S36).

When the process of S36 is completed, or when a negative determination is made in the process of S10, the CPU 52 temporarily ends the series of processes illustrated in FIG.
FIG. 6 shows a procedure of a process related to the determination of the execution request of the multi-injection process. The process shown in FIG. 6 is realized by CPU 52 repeatedly executing a program stored in ROM 54 at a predetermined cycle, for example.

  In the series of processes shown in FIG. 6, the CPU 52 first determines whether or not it is the first cranking start after the start switch of the vehicle is turned on (S50). When determining that it is the first cranking start time (S50: YES), the CPU 52 substitutes the current water temperature THW into the initial water temperature THW0 (S52). When the process of S52 is completed or when the determination of S50 is negative, the CPU 52 determines whether the intake air amount Ga detected by the air flow meter 62 after the cranking is a value capable of accurately calculating the required injection amount Qd. It is determined whether or not acquisition is possible (S54). This processing determines whether or not the predetermined period has elapsed after the start of cranking.

  When determining that the acquisition is possible (S54: YES), the CPU 52 determines whether or not it is time to restart the internal combustion engine 10 (S56). When judging that it is the time of restart (S56: YES), the CPU 52 substitutes the current water temperature THW into the restart-time water temperature THW1 (S58).

Next, the CPU 52 acquires the stop time Tstp as the elapsed time from the time of the automatic stop immediately before the internal combustion engine 10 to the present (S60).
When the process in S60 is completed or when the determination in S56 is negative, the CPU 52 updates the total integrated air amount InG0, which is the integrated value of the intake air amount after the first cranking is started (S62). Here, the total integrated air amount InG0 may be updated by a value obtained by adding the intake air amount Ga to the value of the total integrated air amount InG0 in the previous process of S62. Note that the initial value of the total integrated air amount InG0 is “0”. When the CPU 52 has been restarted, in addition to updating the total integrated air amount InG0, the CPU 52 updates the post-restart integrated air amount InG1, which is an integrated value of the intake air amount Ga from the time of the restart. Note that the initial value of the post-restart integrated air amount InG1 is “0”, and the post-restart integrated air amount InG1 is initialized each time a restart is performed.

  When the process of S62 is completed or a negative determination is made in the process of S54, the CPU 52 proceeds to the process of S64. In the process of S64, the CPU 52 restarts the condition (A) that the current water temperature THW is equal to or higher than the specified temperature Tth, the condition (A) that the total integrated air amount InG0 is equal to or higher than the determination value Inth0, and restarts. It is determined whether the logical product of the post-integrated air amount InG1 and the condition (C) that the integrated air amount InG1 is equal to or greater than the determination value Inth1 is true. This process determines whether the temperature of the intake system of the internal combustion engine 10 including the intake passage 12 and the intake valve 18 has become equal to or higher than the lower limit value of the temperature at which PN falls within the allowable range even after performing the single injection process. This is the processing to be performed.

  Here, the CPU 52 calculates the determination value Inth0 to be a larger value when the initial water temperature THW0 is low than when it is high. This may be realized, for example, by performing a map calculation of the determination value Inth0 by the CPU 52 in a state where map data having the initial water temperature THW0 as an input variable and the determination value Inth0 as an output variable is stored in the ROM 54 in advance. Further, the CPU 52 calculates the determination value Inth1 to be a larger value when the restart-time water temperature THW1 is low than when it is high. The CPU 52 calculates the determination value Inth1 to be larger when the stop time Tstp is longer than when the stop time Tstp is shorter. This is performed by, for example, performing a map calculation of the determination value Inth1 by the CPU 52 in a state where map data having the restart-time water temperature THW1 and the stop time Tstp as input variables and the determination value Inth1 as an output variable is stored in the ROM 54 in advance. It should be realized. Here, the determination value Inth0 is set to zero when the initial water temperature THW0 is equal to or higher than a predetermined temperature higher than the specified temperature Tth. The determination value Inth1 is set to zero when the restart-time water temperature THW1 is equal to or higher than a predetermined temperature. Further, the determination value Inth1 is set to zero when the stop time Tstp is equal to or shorter than a specified time. Note that the CPU 52 sets the determination value Inth1 to zero when it is not after the restart. For this reason, the condition (c) is automatically satisfied when not restarting.

  When determining that the logical product is true (S64: YES), the CPU 52 selects the single injection process (S66). On the other hand, when determining that the logical product is false (S64: NO), the CPU 52 determines whether or not the water temperature THW is equal to or higher than a low threshold TL lower than the specified temperature Tth (S68). Here, since the water temperature THW is low, the required injection amount Qd becomes excessively large, and the time interval between the injection end timing of the intake asynchronous injection and the injection start timing Is of the intake synchronous injection is set to the predetermined time or more. Is determined. When a negative determination is made in the process of S68, the CPU 52 determines that it is difficult to execute the multi-injection process, and shifts to the process of S66. On the other hand, when determining that the water temperature THW is equal to or higher than the low threshold value TL (S68: YES), the CPU 52 selects the multi-injection process (S70). In this case, there is a multi-injection request.

When the processing of S66 and S70 is completed, the CPU 52 ends the series of processing shown in FIG. 6 once.
Incidentally, in the present embodiment, the CPU 52 selects the multi-injection processing or the single-injection processing based on the processing in FIG. 6 even if a negative determination is made in the processing in S10. However, if a negative determination is made in the process of S10, the CPU 52 executes control for injecting a required injection amount of fuel determined from the intake air amount Ga according to the selection result.

Here, the operation and effect of the present embodiment will be described.
When starting the internal combustion engine 10, the CPU 52 selects the single injection process when the logical product of the above conditions (A) to (C) is true, and selects the multi-injection process when the logical product is false. Here, at the time of the first start, the above condition (a) is automatically satisfied. However, since the total integrated air amount InG0 cannot be calculated and is set to zero, which is the initial value, the CPU 52 sets the water temperature THW to the low threshold value TL when the initial water temperature THW0 is not equal to or higher than the predetermined temperature higher than the specified temperature Tth. If not, select the multi-injection process. On the other hand, when the initial water temperature THW0 is equal to or higher than the predetermined temperature, the CPU 52 executes the single injection processing because the logical product is true.

  Further, even when restarting, the CPU 52 determines that the water temperature THW is not lower than the low threshold TL unless the initial water temperature THW0 is equal to or higher than the predetermined temperature higher than the specified temperature Tth unless the stop time Tstp is excessively short. As long as the multi-injection process is selected.

  On the other hand, when the stop time Tstp is excessively short at the time of restart, the CPU 52 determines that the water temperature THW is equal to or higher than the specified temperature Tth and the total integrated air amount InG0 because the determination value Inth1 becomes zero. Is greater than or equal to the determination value Inth0, the single injection process is selected. That is, when the total integrated air amount InG0 is equal to or higher than the determination value InG0 immediately before the stop of the internal combustion engine 10, the CPU 52 selects the single injection process when the water temperature THW is equal to or higher than the specified temperature Tth.

  However, even when the water temperature THW is equal to or higher than the specified temperature Tth, the total integrated air amount InG0 may be less than the determination value Inth0. In this case, there is a possibility that the temperature of the intake valve 18 does not reach a temperature range in which PN can be set within an allowable range. This is because the temperature of the intake valve 18 largely depends on the amount of heat generated in the combustion chamber 24 because the intake valve 18 directly receives the heat in the combustion chamber 24. Therefore, the temperature of the intake valve 18 is uniquely determined by the water temperature THW. Because it is not decided. Therefore, when the total integrated air amount InG0 is less than the determination value Inth0, a situation may occur in which the temperature of the intake valve 18 is not yet sufficiently high in spite of the high water temperature THW. Here, if the specified temperature Tth, which is the determination value of the water temperature THW, is set to a value at which the temperature of the intake valve 18 or the like becomes equal to or higher than the predetermined temperature, the condition (a) may not be provided. However, in that case, the specified temperature Tth must be set to an excessively large value, and even when the process shifts to the single injection process and the PN can be set within the allowable range, the multi-injection process is performed. There are cases where it is executed.

  On the other hand, in the present embodiment, by providing the above condition (a), the specified temperature Tth is set to a smaller value as compared with the case where it is determined whether or not there is a request to execute the multi-injection process only from the above condition (a). Can be set to Therefore, when the PN can be set within the allowable range, the single injection processing can be executed as much as possible. Therefore, an increase in the number of times the port injection valve 16 is driven can be suppressed, and a decrease in the durability of the port injection valve 16 can be suppressed. Further, according to the single injection processing, atomization of fuel can be promoted as compared with the multiple injection processing, and generation of HC can be suppressed.

<Second embodiment>
Hereinafter, the second embodiment will be described with reference to the drawings, focusing on differences from the first embodiment.

  In the above-described embodiment, when restarting, the asynchronous injection amount Qns is calculated based on the immediately preceding stop time Tstp, but there is a concern that the temperature of the intake system cannot be accurately grasped from the immediately preceding stop time Tstp. In particular, in the case of a hybrid vehicle, the driving and stopping of the internal combustion engine 10 may be frequently repeated within a short period of time, so this problem is serious. That is, when the drive time and the stop time are shortened, the temperature of the intake system can be greatly affected by not only the stop time Tstp immediately before the restart but also the driving method and the stop time before that.

  Therefore, in the present embodiment, during the period in which the start switch of the vehicle is in the ON state, the amount becomes larger as the total stop time after the internal combustion engine 10 is driven is longer, The asynchronous injection amount Qns is corrected based on the intermittent integration stop time InT, which is an amount that decreases as the combustion energy amount increases.

  FIG. 7 shows a procedure for calculating the intermittent integration stop time InT. The process shown in FIG. 7 is realized by CPU 52 repeatedly executing a program stored in ROM 54 at a predetermined cycle, for example.

  In the series of processes shown in FIG. 7, the CPU 52 first determines whether or not the internal combustion engine 10 is stopped (S80). If the CPU 52 determines that the intermittent integration stop time InT has been stopped (S80: YES), the CPU 52 adds the intermittent integration stop time InT to a value obtained by adding a predetermined amount ΔT equal to the cycle of a series of processes shown in FIG. Update (S82).

  On the other hand, when determining that the internal combustion engine 10 is not stopped (S80: NO), the CPU 52 determines whether or not the internal combustion engine 10 is being driven (S84). Here, when it is not during cranking, the CPU 52 determines that the internal combustion engine 10 is being driven. If it is determined that the vehicle is being driven (S84: YES), the CPU 52 substitutes the value obtained by multiplying the intake air amount Ga by the gain Kt into the decrease correction amount ΔT1 of the intermittent integration stop time InT (S86). Then, the CPU 52 updates the intermittent integration stop time InT by the larger of the value obtained by subtracting the decrease correction amount ΔT1 from the intermittent integration stop time InT and zero (S88).

  When the processing of S82 and S88 is completed, the CPU 52 substitutes the intermittent integration stop time InT for the stop time Tstp (S90). This processing is for determining parameters used in the processing in S22 in FIG. 3 and the processing in S60 in FIG. As a result, the CPU 52 calculates the stop time correction coefficient Ks to a larger value when the intermittent integration stop time InT is long than when it is short.

Note that the CPU 52 temporarily ends the series of processes illustrated in FIG. 7 when the process of S90 is completed or when a negative determination is made in the process of S84.
<Correspondence>
The correspondence between the items in the above embodiment and the items described in the “Means for Solving the Problems” section is as follows. In the following, the correspondence is shown for each number of the solving means described in the column of "means for solving the problem". [1] The multiple injection processing corresponds to the processing shown in FIG. 2A, and the single injection processing corresponds to the processing shown in FIG. The selection process corresponds to the process of FIG. 6, and the operation process corresponds to the process of S36. [2] This corresponds to the process of S64 when the stop time Tstp is short. That is, when the stop time Tstp is short, the determination value Inth1 becomes zero. Therefore, when the logical product of the above condition (a) and the condition (a) becomes true, an affirmative determination is made in the process of S64. [3-6] Asynchronous injection amount calculation processing corresponds to the processing of S14 to S24. Note that the stop time calculation processing corresponds to the processing in FIG. [7] The synchronous injection amount calculation processing corresponds to the processing of S26 to S30.

<Other embodiments>
This embodiment can be implemented with the following modifications. The present embodiment and the following modifications can be implemented in combination with each other within a technically consistent range.

・ “Asynchronous injection amount calculation processing”
In the above-described embodiment, when the restart is not performed, the asynchronous injection amount Qns is calculated based on the water temperature THW, the number of injections, and the atmospheric pressure Pa, but is not limited thereto. For example, the asynchronous injection amount Qns is calculated based on only the water temperature THW, calculated only based on the water temperature THW and the number of injections, or calculated based only on the water temperature THW and the atmospheric pressure Pa for the above three parameters. Is also good.

  In the above embodiment, at the time of restart, the asynchronous injection amount Qns is calculated based on the water temperature THW, the number of injections, the stop time Tstp, the atmospheric pressure Pa, and the intake pressure Pin, but the present invention is not limited to this. For example, the asynchronous injection amount Qns may be calculated based on only the four parameters, such as calculating the five parameters based on only the water temperature THW, the stop time Tstp, the number of injections, and the intake pressure Pin. Further, for example, calculation based on only three parameters, such as calculation based on only the water temperature THW, the stop time Tstp, and the intake pressure Pin, or calculation based on only two parameters, such as calculation based on only the water temperature THW and the stop time Tstp Or may be calculated based on only one parameter, such as calculation based on only the water temperature THW.

・ “Synchronous injection amount calculation processing”
In the above-described embodiment, when the restart is not performed, the synchronous injection amount Qs is calculated based on the water temperature THW and the atmospheric pressure Pa. However, the present invention is not limited to this. For example, two parameters of the water temperature THW and the atmospheric pressure Pa may be calculated using only the water temperature THW. Further, for example, as in the case of the restart, the synchronous injection amount Qs may be calculated using the intake pressure Pin.

  In the above embodiment, at the time of restart, the synchronous injection amount Qs is calculated based on the water temperature THW, the atmospheric pressure Pa, and the intake pressure Pin, but is not limited thereto. For example, for these three parameters, the synchronous injection amount Qs may be calculated based only on the water temperature THW and the intake pressure Pin. However, the present invention is not limited to this. For example, the above three parameters may be calculated based on the water temperature THW and the atmospheric pressure Pa, or may be calculated using only the water temperature THW.

・ “Asynchronous intake injection in multi-injection processing”
In the above-described embodiment, the intake asynchronous injection is performed such that the fuel injected from the port injection valve 16 reaches the position before the intake valve 18 opens before the intake valve 18 closes. But it is not limited to this. For example, when the rotational speed NE is high and the asynchronous injection amount Qns is excessively large, a part of the period in which the fuel injected from the port injection valve 16 reaches the position before the intake valve 18 is opened is partially opened. It may overlap with the valve period.

・ "About intake synchronous injection"
In the above embodiment, the injection start timing Is is set based on the water temperature THW, the rotation speed NE, and the intake phase difference DIN, but the invention is not limited to this. For example, the above three parameters may be set based on only one of them, or may be set based on only two of them.

・ "Single injection processing"
In the above embodiment, the single injection processing is performed such that the fuel injected from the port injection valve 16 reaches the position before the intake valve 18 opens before the intake valve 18 closes. But it is not limited to this. For example, when the rotation speed NE is high and the required injection amount Qd is large, a part of the period in which the fuel injected from the port injection valve 16 reaches the position before the intake valve 18 is opened is part of the intake valve 18. It may overlap with the valve closing period.

・ "Selection process"
In the above embodiment, the single injection processing is selected when the logical product of the above conditions (A), (A) and (C) is true, but the present invention is not limited to this. For example, the single injection process may be selected when the logical product of the condition (a) and the condition (a) is true.

  Further, for example, when the above condition (A) is satisfied, the single injection process may be selected. This is particularly effective in the case of a vehicle having only an internal combustion engine as a prime mover for generating thrust of the vehicle and not performing the idling stop control, as described in the section “About the vehicle” below.

  For example, when the alcohol concentration such as a detection value of an alcohol concentration sensor that detects the alcohol concentration in the fuel can be acquired, the determination value Inth0 or the determination value Inth1 may be variably set according to the alcohol concentration. In this case, the determination value Inth0 or the determination value Inth1 is set to a larger value when the alcohol concentration is high than when it is low.

・ About the control device
The control device is not limited to the one including the CPU 52 and the ROM 54 and executing software processing. For example, a dedicated hardware circuit (for example, an ASIC or the like) that performs hardware processing on at least a part of the software processing in the above embodiment may be provided. That is, the control device may have any of the following configurations (a) to (c). (A) A processing device that executes all of the above processing in accordance with a program, and a program storage device such as a ROM that stores the program. (B) A processing device and a program storage device that execute a part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (C) A dedicated hardware circuit that executes all of the above processing is provided. Here, there may be a plurality of software processing circuits including a processing device and a program storage device, and a plurality of dedicated hardware circuits. That is, the above processing may be performed by a processing circuit including at least one of one or more software processing circuits and one or more dedicated hardware circuits.

・ About the vehicle
In the above-described embodiment, for example, a so-called hybrid vehicle including a motor generator in addition to an internal combustion engine as a prime mover that generates thrust of the vehicle has been described, but the present invention is not limited to this. For example, a vehicle that includes only an internal combustion engine as a prime mover that generates thrust of the vehicle and that executes idling stop control may be used. Even in this case, by including the above condition (A) in the execution condition of the single injection process, the specified temperature Tth can be set to a lower value compared to the case where only the above condition (A) is used. .

It should be noted that executing the idling stop control is not essential.
·"others"
It is not essential that the internal combustion engine 10 includes a characteristic variable device that changes the characteristic of the intake valve 18. It is not essential that the internal combustion engine 10 includes the throttle valve 14.

  Reference Signs List 10 internal combustion engine, 12 intake passage, 14 throttle valve, 16 port injection valve, 18 intake valve, 20 cylinder, 22 piston, 24 combustion chamber, 26 ignition device, 28 crankshaft, 30 ... exhaust valve, 32 ... exhaust passage, 34 ... catalyst, 36 ... motor generator, 38 ... timing chain, 40 ... intake side camshaft, 42 ... exhaust side camshaft, 44 ... intake side valve timing adjusting device, 50 ... control device 52, CPU, 54, ROM, 56, power supply circuit, 60, crank angle sensor, 62, air flow meter, 64, intake pressure sensor, 66, air-fuel ratio sensor, 68, intake-side cam angle sensor, 70, water temperature sensor, 72 ... Atmospheric pressure sensor.

Claims (7)

Applied to an internal combustion engine having a port injection valve that injects fuel into the intake passage,
An intake synchronous injection that injects fuel in synchronization with an intake valve opening period in order to inject fuel of a required injection amount calculated without depending on a detected value of an intake air amount at the time of starting the internal combustion engine; Either multi-injection processing for executing intake asynchronous injection for injecting fuel at a more advanced timing than intake synchronous injection, or single injection processing for injecting the required amount of fuel by the intake asynchronous injection. Selection process to select,
Operating the port injection valve to execute the process selected by the selection process, and
The selection process selects the single injection process when the temperature of the cooling water of the internal combustion engine is equal to or higher than a specified temperature, and selects the multi-injection process when the temperature of the cooling water is lower than the specified temperature. Control device for internal combustion engine including processing.   When the internal combustion engine is intermittently driven, even when the temperature of the cooling water of the internal combustion engine is equal to or higher than a predetermined temperature, the selection process is performed when the integrated value of the amount of air taken into the intake passage is a predetermined value. 2. The control device for an internal combustion engine according to claim 1, further comprising a process of selecting the multi-injection process until the above-described operation is performed. Performing an asynchronous injection amount calculation process of calculating an asynchronous injection amount that is an injection amount of the intake asynchronous injection in the multi-injection process;
The asynchronous injection amount calculation process includes a process of calculating the asynchronous injection amount to a value larger than a case where the temperature is low and a case where the elapsed time from a stop of the internal combustion engine to a start is long when the temperature is low. 3. The control device for an internal combustion engine according to claim 1, further comprising: calculating the asynchronous injection amount to a value smaller than the asynchronous injection amount. When the internal combustion engine is intermittently driven, the accumulated time during which the internal combustion engine is stopped is reduced when the integrated value of the amount of air drawn into the intake passage after the start of the internal combustion engine is large. A stop time calculation process of calculating an intermittent integrated stop time reduced and corrected at a reduction correction ratio larger than
The control device for an internal combustion engine according to claim 3, wherein the asynchronous injection amount calculation process includes a process of calculating the asynchronous injection amount to be larger when the intermittent integration stop time is longer than when the intermittent integration stop time is shorter.   The control device for an internal combustion engine according to claim 3 or 4, wherein the asynchronous injection amount calculation process includes a process of calculating the asynchronous injection amount to a larger value when the atmospheric pressure is high than when the atmospheric pressure is low. The internal combustion engine includes a throttle valve,
The asynchronous injection amount calculation process includes a process of calculating the asynchronous injection amount to a small value when the start of the internal combustion engine is a restart of the internal combustion engine as compared with a case where the intake pressure is low when the intake pressure is low. The control device for an internal combustion engine according to claim 5, further comprising:   7. A synchronous injection amount calculating process for calculating a synchronous injection amount, which is an injection amount of the intake synchronous injection, based on the temperature without depending on an elapsed time from a stop of the internal combustion engine to a start thereof. A control device for an internal combustion engine according to any one of the preceding claims.