JP6927142B2 - Internal combustion engine control device - Google Patents

Description

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

For example, in Patent Document 1 below, the amount of fuel required based on the amount of intake air is divided into an intake stroke injection that injects fuel into the intake stroke and a combustion stroke injection that injects fuel into the combustion stroke. A control device that executes a multi-injection process that operates a port injection valve is described. Specifically, this control device sets the division ratio between the intake stroke injection and the combustion stroke injection according to the rotation speed of the crankshaft of the internal combustion engine. Especially in the low rotation region, a single injection consisting of only the combustion stroke injection. Processing is being performed.

Japanese Unexamined Patent Publication No. 5-256172

By the way, when deciding whether to execute the multi-injection process or the single-injection process according to the rotation speed as in the above configuration, the execution period of the multi-injection process becomes long depending on how the internal combustion engine is operated. If the execution period of the multi-injection process is long, the number of times the port injection valve is driven increases as compared with the case where the single injection process is performed, so that there is a concern that the durability of the port injection valve may decrease.

Hereinafter, means for solving the above problems and their actions and effects will be described.
1. 1. It is applied to an internal combustion engine equipped with a port injection valve that injects fuel into the intake passage, and is synchronized with the valve opening period of the intake valve in order to inject the required injection amount of fuel, which is the required injection amount in one combustion cycle. By the multi-injection process that executes the intake synchronous injection that injects the fuel, the intake asynchronous injection that injects the fuel at the timing on the advance side of the intake synchronous injection, and the intake asynchronous injection that fuels the required injection amount. A selection process for selecting one of the single injection processes to be injected and an operation process for operating the port injection valve to execute the process selected by the selection process are executed, and the selection process is the internal combustion engine. Control of the internal combustion engine, which is a process of selecting the single injection process when the temperature of the intake system of the engine is equal to or higher than the specified temperature, and selecting the multi-injection process when the temperature of the intake system is lower than the specified temperature. It is a device.

When the temperature of the intake system of the internal combustion engine is low and all the fuel of the required injection amount is injected by intake asynchronous injection, the number of particulate matter (PM) (PN) in the exhaust may increase depending on the load. .. It is presumed that this is because the amount of fuel adhering to the intake system increases, and PM is generated by the shearing of the adhering fuel causing a part of the droplets to flow into the combustion chamber as droplets. Therefore, in the above configuration, a part of the required injection amount is injected by synchronous injection to reduce the asynchronous injection amount and, by extension, the amount of fuel adhering to the intake system. As a result, it is possible to prevent the fuel from flowing into the combustion chamber as droplets due to the shearing of the attached fuel.

However, when the multi-injection process consisting of the intake synchronous injection and the intake asynchronous injection is executed, the durability of the port injection valve is lowered because the number of times the port injection valve is driven increases as compared with the case where the single injection process is executed. Raise concerns. Therefore, in the above configuration, the multi-injection process is executed when the temperature of the intake system is lower than the specified temperature, while the single injection process is executed when the temperature exceeds the specified temperature. Since the PN is unlikely to be noticeable when the temperature of the intake system is high, it is possible to achieve a good balance between suppressing the decrease in the durability of the port injection valve and suppressing the PN in the above configuration.

2. In the above 1, the selection process includes a determination process for determining whether or not the temperature of the intake system of the internal combustion engine is equal to or higher than the specified temperature, and the determination process is an integrated value of the intake air amount of the internal combustion engine. Is a process for determining that the temperature is equal to or higher than the specified temperature on the condition that is equal to or higher than the judgment value, and is for controlling the air-fuel ratio to the target air-fuel ratio based on the amount of fresh air filled in the cylinder of the internal combustion engine. It is a control device of an internal combustion engine that executes a required injection amount calculation process for calculating the required injection amount as an injection amount.

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 the heat generated in the combustion chamber, the temperature of the intake valve can be accurately grasped by using the integrated value. Therefore, the temperature of the intake system can be accurately grasped by executing the determination process of determining that the temperature is equal to or higher than the specified temperature on the condition that the integrated air amount is equal to or higher than the judgment value as in the above configuration.

3. 3. In the above 2, the control device of the internal combustion engine that executes the determination value variable processing for setting the determination value to a value larger than when the temperature of the cooling water of the internal combustion engine is low when the temperature of the cooling water of the internal combustion engine is low at the time of starting the internal combustion engine. be.

When the temperature of the cooling water at the time of starting the internal combustion engine is low, the total amount of combustion energy generated in the combustion chamber becomes larger than when the temperature of the cooling water becomes higher than the specified temperature. Here, when it is necessary to suppress PN, the above determination value is fixed with respect to the temperature of the cooling water under the constraint of executing the multi-injection process as much as possible, or when the temperature of the cooling water at the time of starting is high. Will continue the multi-injection process even if the temperature of the intake system actually reaches the specified temperature. On the other hand, in the above configuration, the temperature of the intake system is specified as compared with the case where the judgment value is fixed with respect to the temperature of the cooling water by variably setting the judgment value according to the temperature of the cooling water at the time of starting. When the temperature rises above the temperature, it is possible to shift to the single injection process as soon as possible.

4. In 2 or 3, the internal combustion engine control device executes a determination value variable process for setting the determination value to a value larger when the period from the stop to the start of the internal combustion engine is longer than when it is short.

When the stop time of the internal combustion engine is shorter than the time required for the internal combustion engine and its surroundings to reach a thermal equilibrium state, the temperature of the intake system such as the intake valve tends to be inconsistent with the temperature of the cooling water. be. Further, when the stop time is shorter than the above-mentioned required time, when the stop time is long, the temperature of the intake system tends to be lower than when the stop time is short. Here, when it is necessary to suppress the PN, the above determination value is fixed with respect to the stop time under the constraint of executing the multi-injection process as much as possible, and when the stop time is short, the temperature of the intake system is actually Even if the specified temperature is reached, the multi-injection process will be continued. On the other hand, in the above configuration, by setting the judgment value variably according to the stop time, the temperature of the intake system becomes equal to or higher than the specified temperature as much as possible as compared with the case where the judgment value is fixed with respect to the stop time. It is possible to shift to the single injection process at an early stage.

5. In any one of the above 2 to 4, in the determination process, the logical product of the integrated value being equal to or higher than the determination value and the temperature of the cooling water of the internal combustion engine being equal to or higher than the predetermined temperature is true. If this is the case, it is a control device for an internal combustion engine that includes a process of determining that the temperature is equal to or higher than the specified temperature.

In the above configuration, the temperature of the intake system that affects the PN becomes equal to or higher than the specified temperature by determining whether or not the temperature of the intake system is equal to or higher than the specified temperature based on the temperature of the cooling water in addition to the integrated value. Whether or not it can be determined with high accuracy.

The figure which shows the control device and the internal combustion engine which concerns on one Embodiment. The block diagram which shows the process executed by the control device which concerns on the same embodiment. (A) and (b) are diagrams showing the injection pattern according to the same embodiment. The flow chart which shows the procedure of the injection valve operation processing which concerns on the same embodiment. The flow chart which shows the procedure of the injection valve operation processing which concerns on the same embodiment. The flow chart which shows the procedure of the injection valve operation processing which concerns on the same embodiment.

Hereinafter, an embodiment of a control device for an internal combustion engine will be described with reference to the drawings.
The internal combustion engine 10 shown in FIG. 1 is the only prime mover that produces thrust for the vehicle. A throttle valve 14 and a port injection valve 16 are provided in the intake passage 12 of the internal combustion engine 10 in this 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 partitioned by the cylinder 20 and the piston 22 as the intake valve 18 opens. In the combustion chamber 24, the air-fuel mixture is subjected to combustion by the spark discharge of the ignition device 26. Then, the combustion energy generated by the combustion is converted into the rotational energy of the crankshaft 28 via the piston 22. The air-fuel mixture used for 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 the intake side camshaft 40 and the exhaust side camshaft 42 via the timing chain 38. In the present 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 side valve timing adjusting 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 side cam shaft 40.

The control device 50 controls the internal combustion engine 10, and in order to control the control amount (torque, exhaust component ratio, etc.), the throttle valve 14, the port injection valve 16, the ignition device 26, and 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 uses the output signal Scr of the crank angle sensor 60, the intake air amount Ga detected by the air flow meter 62, the air-fuel ratio Af detected by the air-fuel ratio sensor 64, and the output of the intake side cam angle sensor 66. The signal Sca and the temperature (water temperature THW) of the cooling water of the internal combustion engine 10 detected by the water temperature sensor 68 are referred to. Note that FIG. 1 shows operation signals MS1 to MS5 for operating each of the throttle valve 14, the port injection valve 16, the ignition device 26, the starter motor 36, and the intake side valve timing adjusting device 44.

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

FIG. 2 shows a part of the processing executed by the control device 50. The process shown in FIG. 2 is realized by the CPU 52 executing the program stored in the ROM 54.
The intake phase difference calculation process M10 is based on the output signal Scr of the crank angle sensor 60 and the output signal Sca of the intake side cam angle sensor 66, and is the phase difference of the rotation angle of the intake side cam shaft 40 with respect to the rotation angle of the crankshaft 28. This is a process for calculating a certain intake phase difference DIN. The target intake phase difference calculation process M12 is a process for variably setting the target intake phase difference DIN * based on the operating point of the internal combustion engine 10. In this embodiment, the operating point is defined by the rotation speed NE and the filling efficiency η. Here, the CPU 52 calculates the rotation speed NE based on the output signal Scr of the crank angle sensor 60, and calculates the filling efficiency η based on the rotation speed NE and the intake air amount Ga. The filling efficiency η is a parameter that determines the amount of fresh air filled in the combustion chamber 24.

The intake phase difference control process M14 outputs an operation signal MS4 to the intake side valve timing adjustment device 44 in order to operate the intake side valve timing adjustment device 44 in order to control the intake phase difference DIN to the target intake phase difference DIN *. It is a process.

The base injection amount calculation process M20 is a process of calculating the base injection amount Qb, which is the base value of the fuel amount for setting the air-fuel ratio of the air-fuel mixture in the combustion chamber 24 as the target air-fuel ratio, based on the filling efficiency η. Specifically, in the base injection amount calculation process M20, for example, when the filling efficiency η is expressed as a percentage, the filling efficiency η is set to the fuel amount QTH per 1% of the filling efficiency η for setting the air-fuel ratio as the target air-fuel ratio. The process may be such that the base injection amount Qb is calculated by multiplying. The base injection amount Qb is a fuel amount calculated to control the air-fuel ratio to the target air-fuel ratio based on the amount of fresh air filled in the combustion chamber 24. Incidentally, the target air-fuel ratio may be, for example, the theoretical air-fuel ratio.

The feedback processing M22 calculates a feedback correction coefficient KAF obtained by adding "1" to the correction ratio δ of the base injection amount Qb as the feedback operation amount, which is the operation amount for feedback-controlling the air-fuel ratio Af to the target value Af *. It is a process to output. Specifically, the feedback processing M22 holds and outputs the output values of the proportional element and the differential element that input the difference between the air-fuel ratio Af and the target value Af *, and the integrated value of the values corresponding to the difference. Let the sum of the output values of be the correction ratio δ.

The low temperature correction process M24 is a process of calculating the low temperature increase coefficient Kw to a value larger than “1” in order to increase the base injection amount Qb when the water temperature THW is less than the predetermined temperature Tth (for example, 60 ° C.). Specifically, the low temperature increase coefficient Kw is calculated to be a larger value when the water temperature THW is low than when it is high. When the water temperature THW is equal to or higher than the predetermined temperature Tth, the low temperature increase coefficient Kw is set to "1", and the correction amount of the base injection amount Qb by the low temperature increase coefficient Kw is set to zero.

The injection valve operation process M30 is a process of outputting an operation signal MS2 to the port injection valve 16 in order to operate the port injection valve 16 based on the base injection amount Qb, the feedback correction coefficient KAF, and the low temperature increase coefficient Kw. More specifically, it is a process of injecting the required injection amount Qd, which is the amount of fuel required to be supplied from the port injection valve 16 to one cylinder within one combustion cycle, from the port injection valve 16. Here, the required injection amount Qd is "KAF · Kw · Qb".

In the present embodiment, the fuel injection process includes two types of processes, a process illustrated in FIG. 3 (a) and a process illustrated in FIG. 3 (b).
FIG. 3A shows two types, an intake synchronous injection in which fuel is injected in synchronization with the valve opening period of the intake valve 18, and an intake asynchronous injection in which fuel is injected at a timing on the advance side of the intake synchronous injection. It is a multi-injection process that executes fuel injection. Specifically, in the intake synchronous injection, the period during which the fuel injected from the port injection valve 16 reaches the position before the intake valve 18 is opened (the downstream end of the intake port, in other words, the inlet portion to the combustion chamber 24) is The fuel is injected so as to be within the valve opening period of the intake valve 18. Here, the start point of the "reaching period" is the timing at which the fuel injected from the port injection valve 16 reaches the position before valve opening at the earliest timing, and the end point is the port injection. 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, in the intake asynchronous injection, the fuel injected from the port injection valve 16 is injected so as to reach the intake valve 18 before the intake valve 18 is opened. 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 is opened, and then flows into the combustion chamber 24 after the valve is opened. be. In the intake asynchronous injection in the present embodiment, the fuel is injected so that the period during which the fuel injected from the port injection valve 16 reaches the position before the opening of the intake valve 18 falls within the valve closing period of the intake valve 18. It shall be.

FIG. 3B is a single injection process that executes only intake asynchronous injection.
In the present embodiment, the multi-injection process is performed with the aim of reducing the number of particulate matter (PM) (PN) in the exhaust. 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 in the region where the filling efficiency η is large to some extent. It is considered that this is because when the filling efficiency η is large, the required injection amount Qd becomes a value larger than when it is small, and as a result, the amount of fuel adhering to the intake system increases. Specifically, when the amount of fuel adhering to the intake system increases to some extent, it is presumed that this is because a part of the adhering fuel flows into the combustion chamber 24 as droplets due to the shearing of the adhering fuel. Therefore, in the present embodiment, by injecting a part of the required injection amount Qd by intake synchronous injection, even when the required injection amount Qd is large, the amount of fuel adhering to the intake system is divided into a large amount of the required injection amount Qd. To reduce the amount of fuel, and eventually reduce the amount of PN.

FIG. 4 shows a processing procedure of the injection valve operation processing M30. The process shown in FIG. 4 is realized by the CPU 52 repeatedly executing the program stored in the ROM 54, for example, at 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. 4, the CPU 52 first determines whether or not it is within a predetermined period after the starter motor 36 is started (S10). Here, the predetermined period is a period during which the amount of air filled in the combustion chamber 24 cannot be accurately grasped and the base injection amount Qb cannot be calculated accurately. When the CPU 52 determines that the period is within the predetermined period (S10: YES), the CPU 52 determines whether or not there is a request for the multi-injection process (S12). When the CPU 52 determines that there is a request for multi-injection processing (S12: YES), it is the water temperature THW, the number of injections after the starter is turned on, and the elapsed time from the previous stop of the internal combustion engine 10 to the current start. Based on the stop time Tstp of the internal combustion engine 10, the asynchronous injection amount Qns, which is the injection amount of the intake asynchronous injection, is calculated (S14). Here, the CPU 52 calculates the asynchronous injection amount Qns to a larger value when the water temperature THW is low than when it is high. Further, the CPU 52 calculates the asynchronous injection amount Qns to a larger value when the stop time Tstp is long than when it is short.

Next, 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 (S16). Here, the CPU 52 calculates the synchronous injection amount Qs to a larger value when the water temperature THW is low than when it is high.

The sum of the asynchronous injection amount Qns and the synchronous injection amount Qs is the required injection amount Qd, which is the injection amount required for one combustion cycle. That is, the processing of S14 and S16 can be regarded as the processing of dividing the fuel having the required injection amount Qd into the asynchronous injection amount Qns and the synchronous injection amount Qs.

Next, the CPU 52 calculates the injection start timing Is of the intake synchronous injection based on the water temperature THW, the rotation speed NE, and the intake phase difference DIN (S18). In this method, the CPU 52 performs a map calculation of the injection start time Is in a state in which map data having the water temperature THW, the rotation speed NE, and the intake phase difference DIN as input variables and the injection start time Is as the output variable is stored in the ROM 54 in advance. It becomes a process. Here, the map data is a set of data of discrete values of input variables and values of output variables corresponding to the values of the input variables. In the map calculation, for example, when the value of the input variable matches one of the values of the input variable of the map data, the value of the output variable of the corresponding map data is used as the calculation result, whereas when the value does not match, the map is used. The process may be such that the value obtained by interpolating the values of a plurality of output variables included in the data is used as the calculation result.

Next, the CPU 52 calculates the injection start timing Ins of the intake asynchronous injection (S20). Here, the CPU 52 calculates the injection start time Ins of the intake asynchronous injection so that the time interval between the injection end time of the intake asynchronous injection and the injection start time Is of the intake synchronous injection is equal to or longer than a predetermined time. Here, the predetermined time is determined by the structure of the port injection valve 16 in order to prevent the retard side injection from starting before the end of the advance side injection among the fuel injections adjacent to each other in chronological order. It's time. Then, the CPU 52 outputs an operation signal MS2 to the port injection valve 16 to inject fuel having an asynchronous injection amount Qns at the injection start time Ins to operate the port injection valve 16, and then operates the port injection valve 16 at the injection start time Is. The operation signal MS2 is output to the port injection valve 16 to inject the fuel of the above, and the port injection valve 16 is operated (S22).

On the other hand, when the CPU 52 determines that there is no execution request for the multi-injection process (S12: NO), the injection required for one combustion cycle is based on the water temperature THW, the number of injections after the starter is turned on, and the stop time Tstp. The required injection amount Qd, which is an amount, is calculated (S24). Next, the CPU 52 sets the injection start time Isin (S26). Then, the CPU 52 outputs the operation signal MS2 to the port injection valve 16 to inject the fuel of the required injection amount Qd at the injection start time Isin, and operates the port injection valve 16 (S22).

The CPU 52 temporarily ends the series of processes shown in FIG. 4 when the process of S22 is completed or when a negative determination is made in the process of S10.
FIG. 5 shows a processing procedure of the injection valve operation processing M30. The process shown in FIG. 5 is realized by the CPU 52 repeatedly executing the program stored in the ROM 54, for example, at a predetermined cycle.

In the series of processes shown in FIG. 5, the CPU 52 first determines whether or not a predetermined period has elapsed since the starter motor 36 was turned on (S30). Then, when it is determined that the predetermined period has elapsed (S30: YES), the CPU 52 determines whether or not there is a multi-injection request (S32). Then, when it is determined that there is a multi-injection request (S32: YES), the CPU 52 calculates the synchronous injection ratio Ks, which is the ratio of the synchronous injection amount Qs to the base injection amount Qb (S34). Here, the CPU 52 calculates the synchronous injection ratio Ks according to the rotation speed NE, the filling efficiency η, the water temperature THW, and the intake phase difference DIN. Specifically, the CPU 52 stores the map data with the rotation speed NE, the filling efficiency η, the water temperature THW, and the intake phase difference DIN as input variables and the synchronous injection ratio Ks as the output variable in advance in the ROM 54, and the synchronous injection ratio Ks by the CPU 52. Is calculated on the map.

Next, the CPU 52 calculates the asynchronous injection ratio Kns as the ratio of the asynchronous injection amount Qns to the required injection amount Qd (S36). Specifically, the CPU 52 calculates the asynchronous injection ratio Kns by subtracting “Ks / (KAF · Kw)” from “1”. Next, the CPU 52 substitutes the value obtained by multiplying the base injection amount Qb by the synchronous injection ratio Ks into the synchronous injection amount Qs (S38). Next, the CPU 52 substitutes the value obtained by multiplying the required injection amount Qd by the asynchronous injection ratio Kns into the asynchronous injection amount Qns (S40).

As a result, the asynchronous injection amount Qns becomes the following value.
Ksn / KAF / Kw / Qb = KAF / Kw / Qb-Ks / Qb
Therefore, the sum of the asynchronous injection amount Qns and the synchronous injection amount Qs is “KAF ・ Kw ・ Qb”, which is equal to the required injection amount Qd. That is, by the processing of S34 to S40, the fuel having the required injection amount Qd is divided into the asynchronous injection amount Qns and the synchronous injection amount Qs. Incidentally, the synchronous injection amount Qs becomes "Ks · Qb" without being influenced by the values of the feedback correction coefficient KAF and the low temperature increase coefficient Kw. This is because the base injection amount Qb is divided into the synchronous injection amount Qs and "(1-Ks) · Qb", and then the corrected value of "(1-Ks) · Qb" is the asynchronous injection amount Qns. Means to be. In this way, the reason for fixing the synchronous injection amount Qs is that the change in the exhaust component ratio when the synchronous injection amount Qs is changed is more remarkable than the change in the exhaust component ratio when the asynchronous injection amount Qns is changed. Is.

Next, the CPU 52 closes the intake valve 18 with the fuel injected at the latest timing among the fuels injected from the port injection valve 16 based on the rotation speed NE, the filling efficiency η, the water temperature THW, and the intake phase difference DIN. The arrival end time AEs shown in FIG. 3A, which is the target value of the timing of reaching the position in the period, is calculated (S42). Then, the CPU 52 calculates the injection start time Is of the intake synchronous injection based on the arrival end time AEs, the synchronous injection amount Qs, and the rotation speed NE (S44). Here, the CPU 52 calculates the injection start time Is to a value on the advance angle side when the synchronous injection amount Qs is large, as compared with the case where the synchronous injection amount Qs is small. Further, the CPU 52 sets the injection start time Is as a value on the advance angle side when the rotation speed NE is large and when it is small. Specifically, the CPU 52 added the injection period by the port injection valve 16 determined from the synchronous injection amount Qs, the flight time until the fuel injected from the port injection valve 16 reaches the position when the intake valve 18 is closed, and the like. The timing at which the angle is advanced with respect to the arrival end time AEs by the value is defined as the injection start time Is.

Next, the CPU 52 calculates the injection start time Ins of the asynchronous injection based on the injection start time Is (S46). Here, the time interval between the injection end time and the injection start time Is of the intake asynchronous injection is set to be equal to or longer than the above-mentioned predetermined time.

By the above process, the injection start time Is of the intake synchronous injection is set independently of the injection start time Ins of the intake asynchronous injection. This is because the above-mentioned arrival end time AEs of the intake synchronous injection is particularly likely to affect the PN and HC in the exhaust.

Then, the CPU 52 injects fuel having an asynchronous injection amount Qns at the injection start time Ins, and then outputs an operation signal MS2 to the port injection valve 16 in order to inject fuel having a synchronous injection amount Qs at the injection start time Is. The port injection valve 16 is operated (S48).

On the other hand, when the CPU 52 determines that there is no request for the multi-injection process (S32: NO), the CPU 52 substitutes "KAF, Kw, Qb" for the requested injection amount Qd (S50). Next, the CPU 52 calculates the injection start timing Isin of the single injection (S52). Specifically, as shown in FIG. 3B, the CPU 52 sets the timing at which the intake valve 18 is advanced by a predetermined amount Δ1 with respect to the valve opening timing as the arrival end timing AEns. Next, the CPU 52 adds a value obtained by adding the injection period by the port injection valve 16 determined from the required injection amount and the flight time until the fuel injected from the port injection valve 16 reaches the position when the intake valve 18 is closed. However, the timing at which the angle is advanced with respect to the arrival end time AEs is set as the injection start time Isin. Returning to FIG. 5, the CPU 52 outputs the operation signal MS2 to the port injection valve 16 to inject the fuel of the required injection amount Qd at the injection start time Isin to operate the port injection valve 16 (S48).

The CPU 52 temporarily ends the series of processes shown in FIG. 5 when the process of S48 is completed or when a negative determination is made in S30.
FIG. 6 shows a procedure of the injection valve operation process M30, particularly related to the determination of the execution request of the multi-injection process. The process shown in FIG. 6 is realized by the CPU 52 repeatedly executing the program stored in the ROM 54, for example, at a predetermined cycle.

In the series of processes shown in FIG. 6, it is determined whether or not the IG signal corresponding to the on / off of the ignition switch is switched from the off state to the on state (S50). When the CPU 52 determines that it is the time of switching (S50: YES), the CPU 52 substitutes the current water temperature THW for the initial water temperature THW0 (S52). When the processing of S52 is completed or when a negative determination is made in the processing of S50, the CPU 52 determines whether or not the intake air amount Ga can be calculated after cranking (S54). This process determines whether or not the predetermined period has elapsed since the starter motor 36 was started.

When the CPU 52 determines that the intake air amount Ga can be calculated (S54: YES), the CPU 52 determines whether or not the internal combustion engine 10 is restarting (S56). Here, at the time of restart, when the IG signal is in the ON state, the internal combustion engine 10 is automatically stopped (idling stop control), the internal combustion engine 10 is stopped, and then the internal combustion engine 10 is automatically started. It means that it is a time. When the CPU 52 determines that it is at the time of restart (S56: YES), the CPU 52 substitutes the current water temperature THW for the restart water temperature THW1 (S58).

Next, the CPU 52 acquires the stop time Tstp as the elapsed time from the automatic stop of the internal combustion engine 10 to the present (S60).
When the processing of S60 is completed or when a negative determination is made in the processing of S56, the CPU 52 updates the total integrated air amount InG0, which is the integrated value of the intake air amount after the starter motor 36 is started (S62). ). Here, the total integrated air amount InG0 may be updated by the value obtained by adding the intake air amount Ga to the value of the total integrated air amount InG0 in the previous processing of S62. The initial value of the total integrated air amount InG0 is set to "0". Further, when the CPU 52 is after the restart, the CPU 52 updates the integrated air amount InG1 after the restart, which is the integrated value of the intake air amount Ga from the restart. The initial value of the integrated air amount InG1 after restart is "0", and the integrated air amount InG1 after restart is initialized each time the restart is performed.

When the processing of S62 is completed or when a negative determination is made in the processing of S54, the CPU 52 shifts to the processing of S64. In the processing of S64, the CPU 52 includes a condition (a) that the total integrated air amount InG0 is the determination value Inth0 or more, and a condition (a) that the integrated air amount InG1 after restart is the determination value Inth1 or more. It is determined whether or not the logical product with the condition (c) that the water temperature THW at the present time is equal to or higher than the predetermined temperature Tth is true. This process is a process of determining whether or not the temperature of the intake system of the internal combustion engine 10 including the intake passage 12 and the intake valve 18 is equal to or higher than the specified temperature. Here, the specified temperature is set to a value at which the PN falls within the permissible range even if the single injection process is executed. The predetermined temperature Tth is preferably set to a specified temperature or higher.

Here, the CPU 52 calculates the determination value Inth0 to be larger when the initial water temperature THW0 is lower than when it is high. This may be realized, for example, by performing a map calculation on the determination value Inth0 by the CPU 52 in a state where the map data having the initial water temperature THW0 as the input variable and the determination value Inth0 as the output variable is stored in the ROM 54 in advance. Further, the CPU 52 calculates the determination value Inth1 to be larger when the water temperature THW1 at restart is high than when it is low. Further, the CPU 52 calculates the determination value Inth1 to a larger value when the stop time Tstp is long than when it is short. This is done, for example, by performing a map calculation on the determination value Inth1 by the CPU 52 in a state where map data in which the restart water temperature THW1 and the stop time Tstp are input variables and the determination value Inth1 is an output variable is stored in the ROM 54 in advance. It should be realized. The CPU 52 sets the determination value Inth1 to zero when it is not after the restart. Therefore, if it is not the time of restart, the above condition (a) is automatically satisfied.

When the CPU 52 determines that the logical product is true (S64: YES), the CPU 52 selects the single injection process (S66). On the other hand, when the CPU 52 determines 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 the low threshold value TL lower than the predetermined temperature Tth (S68). Here, in the low threshold value TL, since the water temperature THW is low, the required injection amount Qd becomes excessively large, and the time interval between the injection end time of the intake asynchronous injection and the injection start time Is of the intake synchronous injection is equal to or longer than the above-mentioned predetermined time. It is for determining whether or not it is not possible. 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 the CPU 52 determines 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 processes of S66 and S70 are completed, the CPU 52 temporarily ends the series of processes shown in FIG.
Here, the operation and effect of this embodiment will be described.

When the IG signal is switched from the off state to the on state, the CPU 52 stores the water temperature THW at that time as the initial water temperature THW0. Further, when the execution request of the automatic start processing after the automatic stop processing occurs, the CPU 52 stores the water temperature THW at that time as the water temperature THW1 at the time of restart. The CPU 52 starts fuel injection after starting the starter motor 36. Here, within a predetermined period after the start of the starter motor 36, the required injection amount Qd is determined according to the water temperature THW. Here, the determination value Inth0 is set to be zero when the initial water temperature THW0 is equal to or higher than a high threshold value higher than the predetermined temperature Tth. Further, the determination value Inth1 is set to be zero when the water temperature THW1 at restart is equal to or higher than the high threshold value. Therefore, when the water temperature THW at the time of starting the starter motor 36 is equal to or higher than the high threshold value, the CPU 52 executes the single injection process, and when it is less than the high threshold value, executes the multi-injection process.

After that, when a predetermined period elapses, the CPU 52 determines that the water temperature THW is equal to or higher than the predetermined temperature Tth and the total integrated air amount InG0 and the integrated air amount InG1 after restart are the determination values Inth0 and Inth1, respectively. The single injection process is executed because it is not necessary to execute the multi-injection process from the viewpoint of PN reduction. Here, even if the water temperature THW is equal to or higher than the predetermined temperature Tth, the total integrated air amount InG0 may be less than the determination value Inth0, or the integrated air amount InG1 after restart may be less than the determination value Inth1. In that case, the temperature of the intake valve 18 may be lower than the specified temperature. 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 unique depending on the water temperature THW. This is because it is not fixed to. Therefore, when the total integrated air amount InG0 is less than the judgment value Inth0 or the integrated air amount InG1 after restart is less than the judgment value Inth1, the temperature of the intake valve 18 is still sufficient for the high water temperature THW. It can be a situation that is not expensive. Here, if the predetermined 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 is equal to or higher than the specified temperature, it is possible not to provide the above conditions (a) and (b). .. However, in that case, the predetermined temperature Tth must be set to an excessively large value, and even when the PN can be kept within the permissible range even when shifting to the single injection process, the multi-injection process can be performed. There will be cases where it will be executed.

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

<Correspondence>
The correspondence between the matters in the above embodiment and the matters described in the column of "Means for Solving the Problem" is as follows. In the following, the correspondence is shown for each number of the solution means described in the column of "Means for solving the problem". [1] The multi-injection process corresponds to the process shown in FIG. 3 (a), and the single injection process corresponds to the process shown in FIG. 3 (b). The selection process corresponds to the process of FIG. 6, and the operation process corresponds to the processes of S22 and S48. [2] The determination process corresponds to the process of S64, and the required injection amount calculation process corresponds to the base injection amount calculation process M20, the feedback process M22, and the low temperature correction process M24. That is, since the required injection amount Qd is "Qb, KAF, Kw", the required injection amount is calculated by calculating the base injection amount Qb, the feedback correction coefficient KAF, and the low temperature increase coefficient Kw by each of the above processes. It can be considered that Qd has been calculated. [3] The determination value variable processing corresponds to the determination value Inth0 and the determination value Inth1 being set according to the water temperature in the processing of S64. [4] The determination value variable processing corresponds to the determination value Inth1 being set according to the stop time Tstp in the processing of S64. [5] The determination process corresponds to the process of S64.

<Other Embodiments>
In addition, this embodiment can be implemented by changing as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

・ "Required injection amount"
(A) Within a predetermined period after the starter is turned on In the above embodiment, the required injection amount Qd is calculated based on the water temperature THW, the number of injections, and the stop time Tstp, but the present invention is not limited to this. For example, the required injection amount Qd may be calculated based only on the water temperature THW, the water temperature THW and the number of injections, or the water temperature THW and the stop time Tstp only for the above three parameters. May be good.

(B) The required injection amount Qd after a lapse of a predetermined period after the starter is turned on may be corrected by the learning value LAF in addition to the low temperature increase coefficient Kw and the feedback correction coefficient KAF. Incidentally, the calculation process of the learning value LAF is a process of inputting the feedback correction coefficient KAF and updating the learning value LAF so that the correction ratio of the base injection amount Qb by the feedback correction coefficient KAF becomes small. It is desirable that the learning value LAF is stored in an electrically rewritable non-volatile memory.

Further, for example, by feed-forward control based on the ratio of fuel other than fuel (disturbance fuel) injected from the port injection valve 16 in one combustion cycle to the amount of fuel flowing into the combustion chamber 24 in one combustion cycle, the disturbance fuel can be used. When the ratio is large, the required injection amount Qd may be calculated so that the required injection amount Qd is smaller than when the ratio is small. Here, as the disturbance fuel, for example, a canister that collects fuel vapor from a fuel tank that stores fuel injected from the port injection valve 16 and an adjustment that adjusts the inflow amount of the fluid in the canister into the intake passage 12. When the internal combustion engine includes the device, there is fuel vapor flowing from the canister into the intake passage 12. Further, for example, when a system for returning the fuel vapor in the crankcase to the intake passage 12 is provided, there is fuel vapor flowing into the intake passage 12 from the crankcase.

・ "About intake asynchronous injection in multi-injection processing"
In the above embodiment, the intake asynchronous injection is performed so that the period during which the fuel injected from the port injection valve 16 reaches the position before the opening of the intake valve 18 falls within the valve closing period of the intake valve 18. However, it is not limited to this. For example, when the rotation speed NE is high and the asynchronous injection amount Qns is excessively large, the intake valve 18 is opened for a part of the period during which the fuel injected from the port injection valve 16 reaches the position before the intake valve 18 is opened. It may overlap with the valve period.

・ "Intake synchronous injection"
(A) Within a predetermined period after the starter is turned on In the above embodiment, the injection start time Is is set based on the water temperature THW, the rotation speed NE, and the intake phase difference DIN, but the present 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.

(B) After a predetermined period has elapsed after the starter is turned on In the above embodiment, the arrival end time AEs is set based on the rotation speed NE, the filling efficiency η, the water temperature THW, and the intake phase difference DIN, but the present invention is not limited to this. For example, the injection start time Is may be directly set based on the rotation speed NE, the filling efficiency η, the water temperature THW, and the intake phase difference DIN. Further, as a parameter indicating the load, which is a parameter indicating the amount of fresh air filled in the combustion chamber 24, for example, the base injection amount Qb may be used instead of the filling efficiency η. Regarding the four parameters of rotation speed NE, load, water temperature THW, and intake phase difference DIN, the arrival end time AEs and injection start time Is can be variably set based on only three of these parameters, or only two parameters. It may be variably set based on, or may be variably set based on only one parameter.

・ "About single injection processing"
In the above embodiment, the single injection process is performed by injecting the fuel so that the period during which the fuel injected from the port injection valve 16 reaches the position before the opening of the intake valve 18 falls within the valve closing period of the intake valve 18. However, it is not limited to this. For example, when the required injection amount Qd is large, a part of the period during which the fuel injected from the port injection valve 16 reaches the position before the intake valve 18 is opened overlaps with the valve closing period of the intake valve 18. There may be.

・ "About judgment processing"
In the above embodiment, when the logical product of the above conditions (a), condition (b) and condition (c) is true, it is determined that the temperature of the intake system is equal to or higher than the specified temperature, but the present invention is not limited to this. For example, when the logical product of the following condition (d) and the condition (c) is true, it may be determined that the temperature of the intake system is equal to or higher than the specified temperature. Here, the condition (d) is a determination value in which the integrated air amount InG1 after restart under the above condition (a) is used as the integrated value of the intake air amount Ga from the immediately preceding start regardless of whether or not the restart is performed. It is a condition that Inth1 is variably set based on the water temperature THW at the time of the immediately preceding start and the elapsed time from the immediately preceding stop to the immediately preceding start. Further, for example, when the condition (d) is satisfied, it may be determined that the temperature of the intake system is equal to or higher than the specified temperature.

In the above embodiment, it is assumed that the idling stop control is executed in the vehicle provided only with the internal combustion engine as the prime mover for generating the thrust of the vehicle, but the present invention is not limited to this. For example, it may be a so-called hybrid vehicle equipped with a rotating electric machine in addition to an internal combustion engine as a prime mover for generating thrust of the vehicle. In this case, if the logical product of the condition (d) and the condition (c) is true, it may be determined that the temperature of the intake system is equal to or higher than the specified temperature. However, when the logical product of the above conditions (a), (b) and (c) is true, it may be determined that the temperature of the intake system is equal to or higher than the specified temperature. However, the condition (a) here is that the integrated value of the intake air amount Ga after the signal that enables the vehicle to travel is switched from off to on is set to the total integrated air amount InG0. The condition (a) is a condition in which the integrated value of the intake air amount Ga from the second and subsequent starts after the signal for enabling the vehicle is switched from off to on is set to the integrated air amount InG1 after restarting. ..

Further, for example, if the idling stop control is not executed, it may be determined that the temperature of the intake system is equal to or higher than the specified temperature when the logical product of the above conditions (a) and (c) is true. Further, it may be determined that the temperature of the intake system is equal to or higher than the specified temperature when the condition (a) is satisfied, and for example, when the condition (c) is satisfied, the temperature of the intake system is equal to or higher than the specified temperature. You may judge.

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

・ "About selection process"
The conditions for selecting the multi-injection process are not limited to those exemplified in the above embodiment. For example, the following conditions (e) and conditions (f) may be provided.

Condition (e): It is a condition that the filling efficiency η is equal to or higher than a predetermined value. This condition is a condition that the amount of fuel adhering to the intake passage 12 may become excessively large and the PN may become remarkable if the single injection process is performed. However, this condition is a condition after a predetermined period has elapsed after the starter is turned on.

Condition (f): It is a condition that the rotation speed NE is equal to or less than the predetermined speed NEth. This condition is a condition that the time interval between the end timing of the intake asynchronous injection and the injection start time Is can be secured to be equal to or longer than the above-mentioned predetermined time. Further, this condition is a condition for suppressing an excessive amount of heat generation due to an increase in the calculation load of the control device 50 because the calculation load of the multi-injection process is larger than that of the single injection process.

・ "About the method of dividing the required injection amount"
(A) Within a predetermined period after the starter is turned on In the above embodiment, the sum of the asynchronous injection amount Qns calculated by the processing of S14 and the synchronous injection amount Qs calculated by the processing of S16 is the required injection amount Qd. , S14, S16 can be regarded as executing the process of dividing the required injection amount Qd into the synchronous injection amount Qs and the asynchronous injection amount Qns. Here, for example, instead of the treatment of S16, the synchronous injection amount Qs may be calculated according to the number of injections and the stop time Tstp in addition to the water temperature THW.

(B) After a predetermined period has elapsed after the starter is turned on In the above embodiment, the ratio of the synchronous injection amount Qs to the base injection amount Qb is shown based on the rotation speed NE, the filling efficiency η, the water temperature THW, and the intake phase difference DIN. The injection ratio Ks is variably set, but the present invention is not limited to this. For example, the required injection amount Qd may be used instead of the filling efficiency η as the load parameter which is a parameter indicating the amount of fresh air filled in the combustion chamber 24. Further, the four parameters of the load parameter, the rotation speed NE, the water temperature THW, and the intake phase difference DIN can be variably set based on only three of them, or variably set based on only two parameters. It may be variably set based on only one parameter. At this time, it is desirable to variably set the load parameter and the water temperature THW by using at least one as much as possible. In addition to the above four parameters, for example, the intake pressure and the flow velocity of the intake air may be used. However, according to the above four parameters, the intake pressure and the flow velocity of the intake air can be grasped.

Further, it is not essential to determine the synchronous injection ratio Ks. For example, the synchronous injection amount Qs may be calculated based on the parameter that defines the synchronous injection ratio Ks in the above embodiment or its modification. In this case, the asynchronous injection amount Qns may be set to "Qb, KAF, Kw-Qs".

For example, the value “KAF · Qb” in which the base injection amount Qb is corrected by the feedback correction coefficient KAF may be divided by the synchronous injection ratio Ks to obtain the synchronous injection amount Qs. In this case, the synchronous injection amount Qs is "Ks, KAF, Qb".

・ "About the variable intake valve characteristics device"
The characteristic variable device for changing the characteristics of the intake valve 18 is not limited to the intake side valve timing adjusting device 44. For example, the lift amount of the intake valve 18 may be changed. In this case, the parameter indicating the valve characteristics of the intake valve 18 is the lift amount or the like instead of the intake phase difference DIN. Therefore, in the above embodiment or its modification, the lift amount or the like is used instead of the intake phase difference DIN. Just do it.

・ "About control device"
The control device is not limited to the one that includes the CPU 52 and the ROM 54 and executes software processing. For example, a dedicated hardware circuit (for example, ASIC or the like) for hardware processing at least a part of the software processed 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 according to a program and a program storage device such as a ROM that stores the program are provided. (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 are provided. (C) A dedicated hardware circuit for executing all of the above processes 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 processing may be executed by a processing circuit including at least one of one or more software processing circuits and one or more dedicated hardware circuits.

·"others"
It is not essential that the internal combustion engine 10 is provided with a characteristic variable device that changes the characteristics of the intake valve 18. It is not essential that the internal combustion engine 10 includes the throttle valve 14.

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 ... Starter motor, 38 ... Timing chain, 40 ... Intake side camshaft, 42 ... Exhaust side camshaft, 44 ... Intake side valve timing adjustment device, 50 ... Control device , 52 ... CPU, 54 ... ROM, 56 ... power supply circuit, 60 ... crank angle sensor, 62 ... air flow meter, 64 ... air-fuel ratio sensor, 66 ... intake side cam angle sensor, 68 ... water temperature sensor.

Claims (5)

Applicable to internal combustion engines equipped with a port injection valve that injects fuel into the intake passage
Intake synchronous injection in which fuel is injected in synchronization with the valve opening period of the intake valve in order to inject fuel in the required injection amount, which is the required injection amount in one combustion cycle, and the advance side of the intake synchronous injection. A selection process that selects one of a multi-injection process that executes intake asynchronous injection that injects fuel at the timing of the above, and a single injection process that injects the required injection amount of fuel by the intake asynchronous injection.
The operation process of operating the port injection valve to execute the process selected by the selection process, and the operation process of executing the process are executed.
In the selection process, the single injection process is selected when the temperature of the intake system of the internal combustion engine is equal to or higher than the specified temperature, and the multi-injection process is selected when the temperature of the intake system is lower than the specified temperature. A control device for an internal combustion engine, which is a process. The selection process includes a determination process for determining whether or not the temperature of the intake system of the internal combustion engine is equal to or higher than the specified temperature.
The determination process is a process of determining that the temperature is equal to or higher than the specified temperature on condition that the integrated value of the intake air amount of the internal combustion engine is equal to or higher than the determination value.
The first aspect of the present invention, wherein the required injection amount calculation process for calculating the required injection amount as the injection amount for controlling the air-fuel ratio to the target air-fuel ratio based on the fresh air amount filled in the cylinder of the internal combustion engine is executed. Internal combustion engine control device. The control device for an internal combustion engine according to claim 2, wherein the determination value variable process for setting the determination value to a value larger than when the temperature of the cooling water of the internal combustion engine is low is higher than when the temperature of the cooling water of the internal combustion engine is low at the time of starting the internal combustion engine. .. The control device for an internal combustion engine according to claim 2 or 3, wherein the determination value variable process for setting the determination value to a value larger than when the period from the stop to the start of the internal combustion engine is long is larger than when the determination value is short. In the determination process, when the logical product of the integrated value being equal to or greater than the determination value and the temperature of the cooling water of the internal combustion engine being equal to or greater than a predetermined temperature is true, the determination process is determined to be equal to or greater than the specified temperature. The control device for an internal combustion engine according to any one of claims 2 to 4, which includes a determination process.

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