JP2020029786A - Internal combustion engine control apparatus - Google Patents

Abstract

To provide an internal combustion engine control apparatus enabling an alcohol content within fuel injecting from both a port injection valve and in-cylinder injection valve to converge as quickly as possible.SOLUTION: A CPU 42 executes: fuel injection by variably setting injection sharing-ratio that is a ratio of fuel injected from a port injection valve 16 to a fuel amount required for injection per combustion cycle, on the basis of a revolution speed of an internal combustion engine and a charging efficiency; active injection in which to modify the injection sharing-ratio in accordance with the aforementioned operating point and to facilitate an exchange of fuel both in the port injection valve 16 and in-cylinder injection valve 20, in a case where a fuel residual amount Qs detected by a center gage 54 increases; and prioritization of fuel injection from the port injection valve 16, in a case where a tip temperature of the in-cylinder injection valve 20 is equal to or lower than a given value.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 for injecting fuel into an intake passage and a direct injection valve for injecting fuel into a combustion chamber.

  For example, Patent Literature 1 below describes a control device for an internal combustion engine including a port injection valve that injects fuel containing alcohol into an intake passage and an in-cylinder injection valve that injects the fuel into a combustion chamber. When the alcohol concentration changes, the control device sets the ratio of injecting fuel from the port injection valve and the in-cylinder injection valve to a ratio different from the normal time. Here, the different ratio is a ratio equal to the ratio of the volume of the fuel passage to the port injection valve and the volume of the fuel passage to the in-cylinder injection valve (paragraph "0028"). This is because the fuel injected from the port injection valve and the fuel injected from the in-cylinder injection valve are quickly replaced by both the fuel injected from the port injection valve and the fuel injected from the in-cylinder injection valve. The aim is to make both alcohol concentrations converge at an early stage.

JP 2014-34943 A

  By the way, when the alcohol concentration changes, depending on the operating point of the internal combustion engine, there is a possibility that the fuel cannot be injected at a ratio equal to the volume ratio.

  In order to solve the above problems, a control device for an internal combustion engine is applied to an internal combustion engine including a port injection valve for injecting fuel into an intake passage and an in-cylinder injection valve for injecting fuel into a combustion chamber. An allocation process for allocating an amount of fuel to be supplied to the combustion chamber of the internal combustion engine to the port injection valve and the in-cylinder injection valve in one combustion cycle based on the operating point; and the port injection valve and the in-cylinder injection. When the alcohol concentration of the fuel supplied to the valve changes, the fuel injection ratio by the port injection valve is increased with respect to the allocation by the allocation process on the condition that the temperature of the in-cylinder injection valve is equal to or lower than a predetermined temperature. Operating processing for injecting fuel by operating at least one of the port injection valve and the in-cylinder injection valve based on the correction processing to be performed and the allocation corrected by the correction processing. , To run.

  In the above configuration, when the alcohol concentration of the fuel supplied to the port injection valve and the in-cylinder injection valve changes, the fuel injection ratio of the port injection valve is adjusted on the condition that the temperature of the in-cylinder injection valve is equal to or lower than a predetermined temperature. Increase preferentially. Since the opportunity of fuel injection by the port injection valve tends to be lower than the opportunity of fuel injection by the in-cylinder injection valve, the alcohol allocation in the fuel injected from the port injection valve is not performed according to the allocation process. The concentration may not converge for a long time. On the other hand, in the above configuration, by giving priority to the injection of fuel from the port injection valve, it is possible to converge the alcohol concentration in the fuel injected from both the port injection valve and the in-cylinder injection valve as early as possible. it can.

FIG. 1 is a diagram showing a control device and an internal combustion engine according to one embodiment. The figure which shows the allocation between the port injection valve and the in-cylinder injection valve concerning the embodiment. 5 is a flowchart showing a procedure of a process executed by the control device according to the embodiment. (A)-(e) is a time chart which shows the execution example of active injection. (A)-(d) is a time chart which shows the example of determination of the presence or absence of execution of active injection.

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 mounted on a vehicle. The intake passage 12 of the internal combustion engine 10 is provided with a throttle valve 14 and a port injection valve 16 in order from the upstream side. The air sucked into the intake passage 12 and the fuel injected from the port injection valve 16 are supplied to the combustion chamber 18. The combustion chamber 18 is provided with a direct injection valve 20 and an ignition device 22. The air-fuel mixture in the combustion chamber 18 is used for combustion by spark discharge from the ignition device 22, and the air-fuel mixture used for combustion is discharged to the exhaust passage 24 as exhaust gas. A catalyst 26 is provided in the exhaust passage 24.

  Fuel is supplied to the port injection valve 16 from the low pressure side delivery pipe 30. Fuel is supplied to the in-cylinder injection valve 20 from the high pressure side delivery pipe 32. The fuel in the fuel tank 34 is supplied to the low-pressure side delivery pipe 30 via the fuel passage 36 and the low-pressure side passage 36a. Further, the fuel in the fuel tank 34 is pressurized by the pump 38 and supplied to the high pressure side delivery pipe 32 through the high pressure side passage 36b. In the present embodiment, the volume of the low-pressure delivery pipe 30 is larger than the volume of the high-pressure delivery pipe 32.

  The control device 40 controls the internal combustion engine 10 and controls the internal combustion engine 10 such as the throttle valve 14, the port injection valve 16, the in-cylinder injection valve 20, and the ignition device 22 in order to control a torque, an exhaust component ratio, or the like as a control amount. The operation unit of the engine 10 is operated. When operating the operation unit, the control device 40 controls the intake air amount Ga detected by the air flow meter 50, the alcohol concentration Da in the fuel passage 36 detected by the alcohol concentration sensor 52, and the fuel detected by the sender gauge 54. The remaining fuel amount Qs in the tank 34 is referred to. In addition, the control device 40 refers to the fuel pressure (in-cylinder pressure Pd) in the high-pressure side delivery pipe 32 detected by the pressure sensor 56 and the output signal Scr of the crank angle sensor 58. Further, the control device 40 refers to the temperature of the cooling water of the internal combustion engine 10 (water temperature THW) detected by the water temperature sensor 60 and the depression amount of the accelerator pedal (accelerator operation amount ACCP) detected by the accelerator sensor 62. The control device 40 includes a CPU 42 and a ROM 44.

  As shown in FIG. 2, the control device 40 supplies the fuel required for one combustion cycle to the port, which is the fuel injection by the port injection valve 16, based on the charging efficiency η and the rotation speed NE that define the operating point of the internal combustion engine 10. The fuel injection control is executed by allocating the fuel injection to the in-cylinder injection, which is the fuel injection by the in-cylinder injection valve 20. More specifically, in the present embodiment, in the region where the charging efficiency η is equal to or less than the specified value, only the port injection (indicated by PFI in the drawing) that is the fuel injection by the port injection valve 16 is executed, In a region equal to or greater than a predetermined value larger than the prescribed value, only in-cylinder injection (indicated by DI in the drawing) which is fuel injection by the in-cylinder injection valve 20 is executed. However, both the prescribed value and the prescribed value are set to smaller values as the rotational speed NE increases. On the other hand, in a region where the charging efficiency η is larger than the specified value and smaller than the predetermined value, both the port injection and the in-cylinder injection (indicated by PFI + DI in the drawing) are executed.

  In the present embodiment, the port injection is executed before the intake valve opens. This aims at increasing the degree of mixing of fuel and air in the air-fuel mixture in the combustion chamber 18. The injection amount allocation setting has the advantage that port injection has the advantage of easily increasing the degree of mixture of the air-fuel mixture, and that the in-cylinder injection has the advantage of easily increasing the charging efficiency by increasing the cooling effect in the combustion chamber 18 due to latent heat of vaporization. It has been optimized in light of this.

  The CPU 42 calculates the rotation speed NE based on the output signal Scr of the crank angle sensor 58, and calculates the charging efficiency η based on the rotation speed NE and the intake air amount Ga. Note that the charging efficiency η is a parameter that determines the amount of air charged into the combustion chamber 18.

  More specifically, the control device 40 sets the injection ratio, which is the ratio of the amount of fuel injected from the port injection valve 16 to the amount of fuel to be injected in one combustion cycle, according to the operating point of the internal combustion engine 10. For example, in a region where the charging efficiency η is equal to or less than the specified value, the injection sharing rate is set to “1”. However, after refueling, control device 40 executes active injection for executing fuel injection at a different injection ratio from the normal injection ratio according to the operating point of internal combustion engine 10 shown in FIG.

  FIG. 3 shows a procedure of a process regarding the active injection. The process shown in FIG. 3 is realized by the CPU 42 repeatedly executing the program stored in the ROM 44 at a predetermined cycle, for example. In the following, a step number of each process is represented by a number preceded by “S”.

  In the series of processes shown in FIG. 3, the CPU 42 first determines whether the logical product of the condition (A) indicating that there is a refueling determination and the condition (A) indicating that the alcohol concentration Da has changed is true. A determination is made (S10). Here, when detecting that the remaining fuel amount Qs detected by the sender gauge 54 has increased, the CPU 42 determines that there is a refueling determination. Further, the CPU 42 sequentially samples the alcohol concentration Da, and determines that the condition (A) is satisfied when the alcohol concentration Da changes based on the time-series data of the sampling values. It should be noted that the determination result indicating that there is a refueling determination is reset after a predetermined time has elapsed.

  When determining that the logical product is true (S10: YES), the CPU 42 changes both the fuel injected from the port injection valve 16 and the fuel injected from the in-cylinder injection valve 20 to the one after refueling. It is determined whether or not the replacement has been completed (S12). Here, when the difference between the estimated value of the alcohol concentration of the fuel in the low-pressure side delivery pipe 30 and the alcohol concentration Da is equal to or smaller than a predetermined value, the CPU 42 determines the fuel injected by the port injection valve 16 after refueling. It is determined that the replacement of the object has been completed. When the difference between the estimated value of the alcohol concentration of the fuel in the high-pressure side delivery pipe 32 and the alcohol concentration Da is equal to or less than a predetermined value, the CPU 42 determines whether the fuel injected by the in-cylinder injection valve 20 has been refueled. It is determined that the switching to has been completed. Here, the CPU 42 estimates the alcohol concentration of the fuel in the low pressure side delivery pipe 30 and the alcohol concentration of the fuel in the high pressure side delivery pipe 32 as follows. First, the CPU 42 calculates the concentration Dab at the branch B to the low-pressure passage 36a and the high-pressure passage 36b. That is, the CPU 42 is provided with the alcohol concentration sensor 52 in the fuel passage 36 in which the integrated value of the sum of the fuel amount injected from the port injection valve 16 and the fuel amount injected from the in-cylinder injection valve 20 is provided. The alcohol concentration Da at the point of time when the volume from the location to the branch portion B is small is defined as the concentration Dab at the branch portion. Then, the CPU 42 determines the concentration Dab of the branch portion B at the time when the integrated value of the fuel injected from the port injection valve 16 is smaller by the volume of the low-pressure side passage 36a with the alcohol concentration of the fuel flowing into the low-pressure side delivery pipe 30. I do. Then, the CPU 42 estimates that the same amount of fuel as the injected fuel flows into the low-pressure delivery pipe 30 along with the injection of the fuel from the port injection valve 16, and estimates the alcohol concentration in the low-pressure delivery pipe 30. Further, the CPU 42 determines the concentration Dab of the branch portion B at the time when the integrated value of the fuel injected from the in-cylinder injection valve 20 is smaller by the volume of the high-pressure side passage 36b as the alcohol of the fuel flowing into the high-pressure side delivery pipe 32. Concentration. Then, the CPU 42 estimates that the same amount of fuel as the injected fuel flows into the high-pressure side delivery pipe 32 with the injection of the fuel from the in-cylinder injection valve 20, and estimates the alcohol concentration in the high-pressure side delivery pipe 32. .

  If the CPU 42 determines that the switching has not been completed for both (S12: YES), the CPU 42 changes the port fuel for both the port injection valve 16 and the in-cylinder injection valve 20 to the fuel immediately after refueling. It is determined whether or not the execution condition of the split active injection that injects fuel from both the injection valve 16 and the in-cylinder injection valve 20 at a predetermined injection rate is satisfied (S14). Here, the predetermined injection division rate is different from the normal injection rate determined according to the operating point of the internal combustion engine 10, and is different from the fuel amount injected from the port injection valve 16 and the fuel amount injected from the in-cylinder injection valve 20. Is made equal to the ratio of the volume of the low pressure side delivery pipe 30 and the low pressure side passage 36a to the volume of the high pressure side delivery pipe 32 and the high pressure side passage 36b.

  The execution conditions include a condition (C) that the charging efficiency η is equal to or greater than a predetermined value, a condition (D) that the accelerator operation amount ACCP is not zero, and the like. Here, the condition (c) is a condition for enabling fuel injection necessary for injecting fuel from both the port injection valve 16 and the in-cylinder injection valve 20 at a predetermined injection rate. The condition (d) is a condition that the rate of decrease of the charging efficiency η is not large.

  When determining that the execution condition is satisfied (S14: YES), the CPU 42 determines whether the injection amount of the direct injection valve 20 becomes equal to or more than the minimum injection amount by the split active injection that injects the fuel at the predetermined injection ratio. It is determined whether or not it is (S16). This can be realized by the CPU 42 calculating the minimum injection amount based on the cylinder inner pressure Pd, and performing a magnitude comparison between the injection amount of the in-cylinder injection valve 20 and the minimum injection amount determined from a predetermined injection ratio. Then, when determining that the injection amount is equal to or more than the minimum injection amount (S16: YES), the CPU 42 determines to execute the divided active injection (S18). On the other hand, when determining that the injection amount is less than the minimum injection amount (S16: NO), the CPU 42 determines whether or not the tip end temperature of the in-cylinder injection valve 20 is equal to or lower than a predetermined temperature Tth (S20). When the operating point of the internal combustion engine 10 is equal to or lower than the charging efficiency η in the broken line shown in FIG. 2, the CPU 42 determines that the temperature is equal to or lower than the predetermined temperature Tth.

  When determining that the temperature is equal to or lower than the predetermined temperature Tth (S20: YES), the CPU 42 determines that all of the fuel amount required to be injected in one combustion cycle is injected by the port injection valve 16 (S22). First, in this embodiment, since the low-pressure side delivery pipe 30 has a larger volume than the high-pressure side delivery pipe 32, the amount of fuel to be injected from the port injection valve 16 in order to completely replace the fuel is in-cylinder. This is because the amount of fuel to be injected from the injection valve 20 becomes larger. Second, in a region where the charging efficiency η is higher than the dashed line shown in FIG. 2, the tip temperature of the in-cylinder injection valve 20 may be excessively high. This is because it is required to inject fuel from the inner injection valve 20 and the number of injection opportunities by the port injection valve 16 is reduced.

  On the other hand, when the CPU 42 determines that the tip temperature is higher than the predetermined temperature Tth (S20: NO), the fuel amount required to be injected in one combustion cycle is equal to or greater than the minimum injection amount of the direct injection valve 20. It is determined whether or not it is (S24). When it is determined that the injection amount is equal to or more than the minimum injection amount (S24: YES), the CPU 42 determines that all of the fuel amount required to be injected in one combustion cycle is injected from the in-cylinder injection valve 20 (S26). On the other hand, when determining that the injection amount is less than the minimum injection amount (S24: NO), the CPU 42 shifts to the processing of S22.

  On the other hand, when the CPU 42 makes a negative determination in the process of S12, the CPU 42 determines whether or not the replacement of the fuel injected by the port injection valve 16 with that after refueling has been completed (S28). If the CPU 42 determines that the processing has not been completed (S28: YES), the CPU 42 proceeds to the processing of S20. On the other hand, when a negative determination is made in the process of S28, the CPU 42 determines whether or not the replacement of the fuel injected by the in-cylinder injection valve 20 with that after refueling has been completed (S30). If the CPU 42 determines that the processing has not been completed (S30: YES), the CPU 42 proceeds to the processing of S24.

  Then, when the processing of S18, S22, S26 is completed, or when a negative determination is made in the processing of S10, S30, the CPU 42 executes processing of injecting fuel in accordance with the determined injection ratio (S32). That is, the CPU 42 outputs the operation signal MS2 to the port injection valve 16 to operate the port injection valve 16 in accordance with the determined injection division ratio, and outputs the operation signal MS3 to the in-cylinder injection valve 20 to output the operation signal MS3 to the cylinder injection valve 20. And at least one process of operating the inner injection valve 20.

When the process of S32 is completed, the CPU 42 temporarily ends a series of processes illustrated in FIG.
Here, the operation and effect of the present embodiment will be described.

  FIG. 4A shows a transition as to whether or not the replacement of the fuel injected from the port injection valve 16 is completed, and FIG. 4B shows the completion of the replacement of the fuel injected from the in-cylinder injection valve 20. FIG. 4C shows a transition of the charging efficiency η. FIG. 4D shows the transition of the temperature at the tip of the in-cylinder injection valve 20, and FIG. 4E shows the transition of the injection ratio.

  In FIG. 4, in both the fuel injected from the port injection valve 16 and the fuel injected from the in-cylinder injection valve 20, the switching to the fuel after refueling has not been completed. It is assumed that the execution condition to be determined is not satisfied. In this case, before the time t1, since the tip end temperature of the in-cylinder injection valve 20 is higher than the predetermined temperature Tth, the CPU 42 sets the injection ratio to “0” and sets the fuel required to be injected in one combustion cycle. All the amount of fuel is injected from the in-cylinder injection valve 20. On the other hand, since the tip end temperature of the in-cylinder injection valve 20 is lower than the predetermined temperature Tth from the time t2 to the time t3, the injection division rate is set to “1” and the fuel amount required to be injected in one combustion cycle is determined. All the fuel is injected from the port injection valve 16.

  As described above, in the present embodiment, when it is not possible to simultaneously efficiently exchange both the fuel injected from the port injection valve 16 and the fuel injected from the in-cylinder injection valve 20, the tip of the in-cylinder injection valve 20 The fuel injection by the port injection valve 16 is prioritized on condition that the temperature is equal to or lower than the predetermined temperature Tth. Thereby, the replacement of the fuel of the port injection valve 16 in which the securing of the injection opportunity tends to be lower than that of the in-cylinder injection valve 20 can be executed as early as possible.

  When the fuel is replaced, the CPU 42 tends to hardly obtain a highly accurate value of the alcohol concentration in the injected fuel. When the internal combustion engine 10 is cold-started by injecting fuel from the port injection valve 16 based on the low-precision alcohol concentration, there is a concern that the startability is reduced. This is because the amount of fuel adhering and remaining in the intake passage 12 without flowing into the combustion chamber 18 greatly depends on the alcohol concentration. Therefore, if the accuracy of the alcohol concentration referred to in the control is low, the amount of adhesion is appropriately grasped. This is because the controllability of the air-fuel ratio of the air-fuel mixture in the combustion chamber 18 is reduced.

  Further, when the charging efficiency η sharply increases and the injection rate is switched from “1” to “0” in a state where the accuracy of the alcohol concentration referred to in the control is low, the control of the air-fuel ratio in the combustion chamber 18 is performed. There is a possibility that torque controllability may be reduced due to a reduction in performance.

On the other hand, in this embodiment, in both the port injection valve 16 and the in-cylinder injection valve 20, the fuel exchange can be executed as early as possible.
FIG. 5A shows the transition of the remaining fuel amount, FIG. 5B shows the transition of the presence or absence of the refueling determination, FIG. 5C shows the transition of the alcohol concentration Da, and FIG. 2) shows the transition of the execution of active injection for changing the injection ratio with respect to the injection pattern shown in FIG.

  After the fuel remaining amount increases due to the refueling at time t3, when the control device 40 is activated at time t4, the CPU 42 determines the refueling based on the change in the fuel remaining amount Qs detected by the sender gauge 54. do. Thereafter, when the internal combustion engine 10 is started, the fuel in the fuel tank 34 passes near the alcohol concentration sensor 52 in the fuel passage 36, so that the alcohol concentration Da changes. Thereby, the CPU 42 executes the active injection by making an affirmative determination in S10 of FIG. As described above, in the present embodiment, by providing the processing of S10, the active injection is performed unnecessarily by performing the active injection after the refueling and when the alcohol concentration Da changes. Thus, the fuel injection shown in FIG. 2 can be executed as much as possible. As a result, the exhaust characteristics can be better controlled and the torque fluctuation can be suppressed as compared with the case where the active injection is performed unnecessarily.

<Correspondence>
The correspondence between the items in the above embodiment and the items described in the section of “Means for Solving the Problem” is as follows. The allocation processing corresponds to the processing shown in FIG. 2, the correction processing corresponds to the processing of S22 when the charging efficiency η is larger than the specified value, and the operation processing corresponds to the processing of S32.

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

-In the process of S10, the condition (A) may be deleted.
-The process of S18 may be deleted.
The process for determining whether or not the fuel injected by the port injection valve 16 has been replaced by that after refueling is not limited to the process illustrated in the above embodiment. For example, after making an affirmative determination in S10, the process may be determined to be replaced when the integrated value of the amount of fuel injected from the port injection valve 16 is equal to or greater than a predetermined value.

  The process of determining whether or not the fuel injected by the in-cylinder injection valve 20 has been replaced by the one after refueling is not limited to the process illustrated in the above embodiment. For example, after making an affirmative determination in S10, the process may be such that when the integrated value of the amount of fuel injected from the in-cylinder injection valve 20 is equal to or greater than a predetermined value, it is determined that the fuel has been replaced.

  In the above embodiment, the volume of the low-pressure side delivery pipe 30 is larger than the volume of the high-pressure side delivery pipe 32. However, the present invention is not limited to this.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 12 ... Intake passage, 14 ... Throttle valve, 16 ... Port injection valve, 18 ... Combustion chamber, 20 ... In-cylinder injection valve, 22 ... Ignition device, 24 ... Exhaust passage, 26 ... Catalyst, 30 ... Low pressure Side delivery pipe, 32 ... High pressure side delivery pipe, 34 ... Fuel tank, 36 ... Fuel passage, 36a ... Low pressure side passage, 36b ... High pressure side passage, 38 ... Pump, 40 ... Control device, 42 ... CPU, 44 ... ROM, 50: air flow meter, 52: alcohol concentration sensor, 54: sender gauge, 56: pressure sensor, 58: crank angle sensor, 60: water temperature sensor, 62: accelerator sensor.

Claims (1)

Applied to an internal combustion engine including a port injection valve that injects fuel into an intake passage and an in-cylinder injection valve that injects fuel into a combustion chamber,
An allocation process of allocating an amount of fuel to be supplied to a combustion chamber of the internal combustion engine in one combustion cycle to the port injection valve and the in-cylinder injection valve based on an operating point of the internal combustion engine;
When the alcohol concentration of the fuel supplied to the port injection valve and the in-cylinder injection valve changes, the port is allocated to the port by the allocation process on the condition that the temperature of the in-cylinder injection valve is equal to or lower than a predetermined temperature. A correction process for increasing the fuel injection ratio by the injection valve;
A control device for an internal combustion engine that executes an operation process of injecting fuel by operating at least one of the port injection valve and the in-cylinder injection valve based on the allocation corrected by the correction process.