JP4023169B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an internal combustion engine that appropriately maintains an air-fuel ratio (A / F) of exhaust gas discharged from the internal combustion engine.
[0002]
[Prior art]
Conventionally, a fuel pump is used as one component in a fuel supply system that supplies a fuel injection amount to an internal combustion engine. The fuel pump discharge amount [l / h: liter per hour] of the fuel pump increases as the battery voltage [V: volt] increases as shown in the general characteristic diagram of FIG. 7, and the battery voltage is the same. It is known that even before the endurance indicated by the “round black paint” symbol and after the endurance indicated by the “square black paint” symbol, it is lowered due to mechanical deterioration or the like.
[0003]
[Problems to be solved by the invention]
According to the characteristic diagram of FIG. 7, the minimum operating voltage of the fuel pump is 11 [V], and the maximum required fuel injection amount required in accordance with the operating state of the internal combustion engine is about 150 [l / h]. . Here, in the fuel pump discharge amount before endurance, even if the battery voltage fluctuates and becomes close to the minimum operating voltage, the “shaded area” shown in FIG. 7 surrounded by the maximum required fuel injection amount and the minimum operating voltage. Is over. For this reason, the maximum required fuel injection amount can be supplied to the internal combustion engine, and the air-fuel ratio of the exhaust gas discharged from the internal combustion engine can be feedback controlled near the theoretical air-fuel ratio.
[0004]
By the way, when the battery voltage fluctuates and the fuel pump discharge amount after the endurance becomes as low as about 11.8 [V] or less, as shown by the “double hatched (mesh) region” in FIG. It is below the amount. Then, in this “double hatched region”, the maximum required fuel injection amount cannot be supplied to the internal combustion engine, that is, the fuel injection amount becomes insufficient, and as a result, the exhaust gas exhausted from the internal combustion engine becomes empty. There was a problem that the fuel ratio became lean.
[0005]
The same applies to the injector (fuel injection valve), and the maximum required fuel injection amount cannot be supplied depending on the fluctuation of the battery voltage or the degree of durability deterioration, and the fuel injection amount for air-fuel ratio control becomes insufficient. There was a problem that.
[0006]
Therefore, the present invention has been made to solve such a problem, and even when the maximum required fuel injection amount required by the internal combustion engine becomes impossible to supply, the air-fuel ratio of the exhaust gas discharged from the internal combustion engine is reduced. It is an object of the present invention to provide a control device for an internal combustion engine that can perform feedback control in the vicinity of the theoretical air-fuel ratio and can perform normal feedback control when the maximum required fuel injection amount can be supplied.
[0007]
[Means for Solving the Problems]
According to the control apparatus for an internal combustion engine of claim 1, the maximum fuel injection amount that can be supplied by the fuel supply means at the present time according to various operating parameters of the internal combustion engine by the fuel limit value calculation means is the fuel injection quantity limit value. When the required fuel injection amount calculated by the required fuel amount calculation means exceeds this fuel injection amount limit value, the air quantity control means supplies the internal combustion engine so that the required fuel injection amount falls below the fuel injection amount limit value. The amount of air to be controlled is limited. In other words, if the fuel supply system becomes insufficient in capacity, the air-fuel ratio of the exhaust gas discharged from the internal combustion engine becomes lean. At this time, the required fuel injection amount is supplied to the internal combustion engine so as to be less than the fuel injection amount limit value. The amount of air to be controlled is controlled. This makes it possible to control the air-fuel ratio of the exhaust gas discharged from the internal combustion engine close to the stoichiometric air-fuel ratio even when the fuel supply system becomes insufficient in capacity.
The air amount control means starts the restriction control of the air amount to the internal combustion engine when the required fuel injection amount continuously exceeds the fuel injection amount limit value for a predetermined period or more. Since the limit control of the air amount to the internal combustion engine is executed only when the fuel injection amount limit value is surely exceeded, the reliability of this control is improved.
Then, in the air amount control means, the restriction control of the air amount to the internal combustion engine is executed, stopped, and when the stop period when the repeat execution and the sequential repetition are shorter than a predetermined period, that is, to the internal combustion engine. When the air amount restriction control is executed recently, it is assumed that the fuel supply system is in shortage of capacity, and if the required fuel injection amount exceeds the fuel injection amount limit value, the air amount to the internal combustion engine is immediately Limit control is started, and thereby, the air-fuel ratio of the exhaust gas discharged from the internal combustion engine is suppressed from greatly deviating from the stoichiometric air-fuel ratio.
[0008]
In the fuel limit value calculating means in the control device for an internal combustion engine according to claim 2, the fuel injection amount limit value is calculated based on at least the engine speed of the internal combustion engine or the battery voltage. That is, the capacity in the current fuel supply system varies based on the battery voltage and the like, and the margin for lean depends on the engine speed, so that an appropriate fuel injection amount limit value is calculated by considering these parameters. .
[0009]
In the control device for an internal combustion engine according to claim 3, the fuel injection amount limit value has a hysteresis characteristic when compared with the required fuel injection amount, and when the required fuel injection amount exceeds the fuel injection amount limit value, There is a difference in the fuel injection amount limit value in which the hysteresis is taken into account when the injection amount is equal to or less than the fuel injection amount limit value. Thereby, the stability of control when the required fuel injection amount increases or decreases near the fuel injection amount limit value is ensured.
[0010]
According to a fourth aspect of the present invention, there is provided an internal combustion engine control apparatus comprising: an electronic throttle control mechanism in which a throttle opening degree of a throttle valve disposed in an intake passage of an internal combustion engine as an air amount control means can be changed via an actuator based on a control command value; To do. For this reason, when the capacity of the fuel supply system becomes insufficient, the electronic throttle control mechanism restricts the amount of air supplied to the internal combustion engine, so that the air-fuel ratio of the exhaust gas discharged from the internal combustion engine is reduced to the stoichiometric air-fuel ratio. It becomes possible to maintain in the vicinity.
[0011]
The control apparatus for an internal combustion engine according to claim 5 is a variable valve lifting control mechanism in which the air amount control means is disposed in the intake valve of the internal combustion engine and the lift amount can be changed via the actuator based on the control command value. is there. For this reason, when the capacity of the fuel supply system becomes insufficient, the amount of air supplied to the internal combustion engine is limited and controlled by the variable valve lifting control mechanism, so that the air-fuel ratio of the exhaust gas discharged from the internal combustion engine It becomes possible to maintain in the vicinity of the fuel ratio.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples.
[0015]
FIG. 1 is a schematic configuration diagram showing a double overhead cam type internal combustion engine (engine) to which an internal combustion engine control apparatus according to an embodiment of the present invention is applied and its peripheral devices.
[0016]
In FIG. 1, an intake passage 2 and an exhaust passage 3 are connected to an internal combustion engine 1 composed of a plurality of cylinders. In the intake passage 2, an air flow meter 5 that detects an intake air amount GN introduced from an upstream air cleaner 4, a throttle valve 6, a throttle opening sensor 7 that detects a throttle opening TA of the throttle valve 6, an injector (fuel injection) 8) is provided. The throttle valve 6 is provided with a known electronic throttle mechanism that can open and close its throttle opening degree by driving an electric motor 9 as an actuator based on a depression amount of an accelerator pedal (not shown).
[0017]
The injector 8 is connected to a fuel pump 12 in a fuel tank 11 as a fuel supply system. The fuel is pumped to the injector 8 by the fuel pump 12. The fuel pressure (fuel pressure) FP in the injector 8 is detected by a fuel pressure sensor 13 disposed in the vicinity of the injector 8. The battery voltage from the in-vehicle battery (not shown) is measured by an A / D converter (not shown) incorporated in an input / output circuit 35 of the ECU 30 described later.
[0018]
The exhaust passage 3 has an air-fuel ratio sensor 15 that outputs a linear air-fuel ratio signal VOX1 corresponding to the air-fuel ratio of the exhaust gas discharged from the internal combustion engine 1, a three-way catalyst 16, and a three-way catalyst 16 downstream thereof. That outputs a voltage signal VOX2 corresponding to whether the oxygen concentration of the exhaust gas that has passed through is rich or lean with respect to the stoichiometric air-fuel ratio.₂) A sensor 17 is provided. The three-way catalyst 12 carries a catalyst component such as platinum or rhodium and an additive such as cerium or lanthanum, and the exhaust gas passes through the activated three-way catalyst 16 so as to be a harmful component therein. (Carbon monoxide), HC (hydrocarbon), NOx (nitrogen oxide), etc. are purified.
[0019]
A crank position sensor 22 that outputs a crank angle signal θ1 is disposed on the crankshaft 21 of the internal combustion engine 1. A known hydraulically driven variable valve lifting control mechanism (hereinafter referred to as “VVL”) 25 is connected to the camshaft 24 of the intake valve 23 of the internal combustion engine 1. This VVL 25 drives the camshaft 24 of the internal combustion engine 1 in the axial direction of the intake valve 23 by a hydraulic control valve (hereinafter referred to as “OCV”) 27 as an actuator for adjusting and controlling the hydraulic pressure of the hydraulic oil. By changing the lift amount of the intake valve 23, the opening / closing timing and the intake amount are controlled. In the present embodiment, VVL is not connected to the camshaft 29 of the exhaust valve 28 of the internal combustion engine 1. Further, a driving force transmission system between the crankshaft 21 and the camshafts 24 and 29, an oil pump for pumping hydraulic oil from the internal combustion engine 1 to the OCV 27, and its oil passage are omitted.
[0020]
The intake air amount signal GN from the air flow meter 5, the throttle opening signal TA from the throttle opening sensor 7, the fuel pressure signal FP from the fuel pressure sensor 13, the battery voltage VB from the voltage sensor 14, and the air / fuel ratio signal from the air / fuel ratio sensor 15. Various sensor signals such as VOX 1, voltage signal VOX 2 from the oxygen sensor 17, and crank angle signal θ 1 from the crank position sensor 21 are input to an ECU (Electronic Control Unit) 30.
[0021]
The ECU 30 includes a CPU 31 as a central processing unit that executes various known arithmetic processes, a ROM 32 that stores a control program and a control map, a RAM 33 that stores various data, a B / U (backup) RAM 34, and the like. And is connected via a bus 36 to an input / output circuit 35 for inputting detection signals from various sensors and outputting control signals to various actuators.
[0022]
Based on the crank angle signal .theta.1 from the crank position sensor 22, the ECU 30 calculates the engine rotational speed NE, the control duty DV for the OCV 27, and the like. Further, the air-fuel ratio signal VOX1 from the air-fuel ratio sensor 15 is input to the ECU 30, the air-fuel ratio of the exhaust gas is detected, and rich / lean determination of the air-fuel mixture is executed. When the ECU 30 reverses from rich to lean and when it reverses from lean to rich, the FAF value, which is the air-fuel ratio feedback correction coefficient, is greatly changed (skipped) in steps to increase or decrease the fuel injection amount TAU. When rich or lean, well-known air-fuel ratio feedback control for gradually increasing or decreasing the FAF value is executed.
[0023]
Further, the ECU 30 obtains the basic fuel injection amount from the engine speed NE and the intake air amount GN, and corrects the basic fuel injection amount by the FAF value or the like to obtain the final fuel injection amount TAU. The fuel is injected at the injection timing. Then, the fuel pump discharge amount from the fuel pump 12 is controlled based on the fuel pressure FP detected by the fuel pressure sensor 13 in the ECU 30.
[0024]
Next, based on the flowchart of FIG. 2 showing the processing procedure of the throttle control in the CPU 31 in the ECU 30 used in the control device for an internal combustion engine according to an example of the embodiment of the present invention, FIG. This will be described with reference to FIG. Here, FIG. 3 is a time chart showing transition states of various control amounts corresponding to the processing of FIG. This throttle control routine is repeatedly executed by the CPU 31 every predetermined time.
[0025]
In FIG. 2, first, in step S101, a fuel injection amount limit value is calculated. As shown in FIG. 7, the fuel injection amount limit value is the maximum required fuel injection amount according to the fuel pump discharge amount [l / h] after the endurance of the fuel pump (not shown) and the operating state of the internal combustion engine 1. It is calculated based on [l / h] and the battery voltage [V] at this time, and is expressed as the upper limit value of the fuel pump discharge amount in the “shaded area” shown in FIG. Further, the fuel injection amount limit value is increased or decreased depending on the engine speed of the internal combustion engine 1. That is, the fuel injection amount limit value is increased in the low rotation speed region with a large lean margin, and the fuel injection amount limit value is decreased in the high rotation speed region with a small lean margin.
[0026]
Next, the routine proceeds to step S102, where it is determined whether the required fuel injection amount according to the operating state of the internal combustion engine 1 at this time exceeds the fuel injection amount limit value calculated at step S101. When the determination condition in step S102 is satisfied, that is, when the requested fuel injection amount exceeds the fuel injection amount limit value (time t0, time t3 in FIG. 3), the process proceeds to step S103, and the delay counter is incremented. Note that the delay counter is incremented every time this routine is executed unless it is reset halfway after the start of the increment until it exceeds a predetermined value α, which will be described later, and reaches a predetermined value (a preset maximum value adapted to the characteristics of the vehicle).
[0027]
Next, the process proceeds to step S104, where it is determined whether the delay counter exceeds a predetermined value α. When the determination condition of step S104 is satisfied, that is, when the delay counter exceeds the predetermined value α, the process proceeds to step S105, and the output restriction execution flag is set to “ON (time t1 in FIG. 3)”. This output restriction execution flag is set to “OFF” by default. Next, the process proceeds to step S106, and since the output restriction execution flag is set to “ON” in step S105, the throttle closing control process is executed as the output restriction for the internal combustion engine 1.
[0028]
In this throttle closing control, the required fuel injection amount exceeds the fuel injection amount limit value calculated in step S101, that is, exceeds the capacity in the fuel supply system, so that the required fuel injection amount falls below the fuel injection amount limit value. The throttle opening TA of the throttle valve 6 in the known electronic throttle mechanism is controlled to the closed side by the electric motor 9, and the amount of air supplied to the internal combustion engine 1 is controlled to be limited. As a result, the air-fuel ratio of the exhaust gas is controlled so as to fall within a narrow area called “air-fuel ratio window” around the stoichiometric air-fuel ratio at which the three-way catalyst 16 can simultaneously obtain a high purification rate of the three components of CO, HC and NOx. It becomes possible. Next, the process proceeds to step S107, where the delay cancellation counter is set to "initial value (maximum value preset in conformity with vehicle characteristics)" (time t1 to time t2 in FIG. 3), and this routine is terminated. .
[0029]
On the other hand, when the determination condition of step S104 is not satisfied, that is, when the delay counter is smaller than the predetermined value α, the process proceeds to step S108, and it is determined whether the delay cancellation counter is greater than “0 (zero)”. When the determination condition of step S108 is satisfied, that is, when the delay cancellation counter is a value other than “0”, the throttle closing control process is executed almost immediately before the determination time, and this time a delay time is provided. If it is not necessary, the process immediately proceeds to step S105 described above, and the output restriction execution flag is set to “ON” (time t3 in FIG. 3). Similarly, in step S106, after the throttle closing control process is executed, in step S107, the delay cancellation counter is set to the “initial value” (after time t3 in FIG. 3), and this routine is terminated.
[0030]
On the other hand, when the determination condition of step S102 is not satisfied, that is, when the required fuel injection amount is as small as the fuel injection amount limit value or less, the process proceeds to step S109. In step S109, a value obtained by subtracting a predetermined value ΔH set as a hysteresis amount in order to provide hysteresis characteristics from the fuel injection amount limit value calculated in step S101 with the output limit execution flag being “ON” and the required fuel injection amount. It is determined whether the number exceeds. When the determination condition of step S109 is satisfied, the process proceeds to step S103 described above, and thereafter the same processing is executed.
[0031]
On the other hand, when the determination condition of step S109 is not satisfied, that is, when the output restriction execution flag is “OFF” or the required fuel injection amount is less than the value obtained by subtracting the predetermined value from the fuel injection amount limit value, the process proceeds to step S110. . In step S110, after the delay counter is reset to "0", the process proceeds to step S111, and the output restriction execution flag is set to "OFF" (time t2 to time t3 in FIG. 3). Next, the routine proceeds to step S112, where the throttle normal control process is executed.
[0032]
In this throttle normal control, the requested fuel injection amount is less than the fuel injection amount limit value calculated in step S101, and the throttle opening degree TA of the throttle valve 6 in the electronic throttle mechanism is a command value from the ECU 30. It is controlled by the electric motor 9 so as to follow the opening. As a result, the air-fuel ratio of the exhaust gas is controlled so as to fall within the “air-fuel ratio window” region around the stoichiometric air-fuel ratio. In step S113, the delay cancel counter is decremented (time t2 to time t3 in FIG. 3), and this routine ends. The delay cancellation counter is guarded so as not to become smaller than “0”.
[0033]
On the other hand, when the determination condition of step S108 is not satisfied, that is, when the delay cancellation counter is “0” (time t0 to time t1 in FIG. 3), the process proceeds to the above-described step S111, and thereafter the same processing is performed. Is executed.
[0034]
Next, based on the flowchart of FIG. 4 which shows the 1st modification of the process sequence of the throttle control in CPU31 in ECU30 used with the control apparatus for internal combustion engines concerning one Example of embodiment of this invention. explain. This throttle control routine is repeatedly executed by the CPU 31 every predetermined time. Here, for the same processing as the throttle control routine in the above-described embodiment, the corresponding step number is described, and the detailed description thereof is omitted.
[0035]
In FIG. 4, steps S201 to S206 correspond to steps S101 to S106 in the above-described embodiment. Steps S207 to S210 correspond to steps S109 to S112 in the above-described embodiment.
[0036]
That is, in the first modification, the predetermined value ΔH as a hysteresis amount with respect to the fuel injection amount limit value in the above-described embodiment is considered and the delay counter is used, but without using the delay cancellation counter. It has been simplified. For this reason, the difference from the throttle control routine in the above-described embodiment is that the delay time until the delay counter exceeds a predetermined value α is always set when shifting from the throttle normal control process to the throttle closing control process. It is to be done.
[0037]
Next, based on the flowchart of FIG. 5 which shows the 2nd modification of the process procedure of the throttle control in CPU31 in ECU30 used with the control apparatus for internal combustion engines concerning one Example of embodiment of this invention. explain. This throttle control routine is repeatedly executed by the CPU 31 every predetermined time. Here, for the same processing as the throttle control routine in the above-described embodiment, the corresponding step number is described, and the detailed description thereof is omitted.
[0038]
In FIG. 5, Steps S301 to S304 correspond to Steps S101, S102, S105, and S106, respectively, in the above-described embodiment. Steps S305 to S307 correspond to steps S109, S111, and S112 in the above-described embodiment.
[0039]
That is, in the second modification, the predetermined value ΔH as a hysteresis amount with respect to the fuel injection amount limit value in the above-described embodiment is taken into consideration, but is simplified without using a delay counter and a delay cancellation counter. . For this reason, the difference from the throttle control routine in the above-described embodiment is that when the required fuel injection amount exceeds the fuel injection amount limit value, the routine immediately shifts from the throttle normal control processing to the throttle closing control processing. When the injection amount becomes equal to or less than the value obtained by subtracting the hysteresis amount from the fuel injection amount limit value, the throttle closing control process is returned to the throttle normal control process.
[0040]
Next, based on the flowchart of FIG. 6 which shows the 3rd modification of the process sequence of the throttle control in CPU31 in ECU30 used with the control apparatus for internal combustion engines concerning one Example of embodiment of this invention. explain. This throttle control routine is repeatedly executed by the CPU 31 every predetermined time.
[0041]
In FIG. 6, Steps S401 to S403 correspond to Steps S101, S102, and S106 in the above-described embodiment. Step S404 corresponds to step S112 in the above-described embodiment.
[0042]
That is, in the third modified example, the hysteresis amount with respect to the fuel injection amount limit value in the above-described embodiment is not taken into consideration, and is simplified without using the delay counter and the delay cancellation counter. Further, the hysteresis for the fuel injection amount limit value is not taken into consideration. For this reason, the difference from the throttle control routine in the above-described embodiment is that when the required fuel injection amount exceeds the fuel injection amount limit value, the routine immediately shifts from the throttle normal control processing to the throttle closing control processing. When the injection amount becomes equal to or less than the fuel injection amount limit value, the throttle closing control process is immediately returned to the throttle normal control process.
[0043]
As described above, the control device for the internal combustion engine of the embodiment and the first to third modifications is achieved by the injector 8, the fuel pump 12, the ECU 30, and the like that supply the fuel injection amount to the internal combustion engine 1. The fuel supply means, the required fuel amount calculation means achieved by the ECU 30 for calculating the required fuel injection amount required in the internal combustion engine 1, and the fuel supply means at the present time according to various operating parameters of the internal combustion engine 1 The fuel limit value calculating means achieved by the ECU 30 that calculates the maximum fuel injection amount that can be supplied as the fuel injection amount limit value, and the required fuel injection amount calculated by the required fuel amount calculation means is the fuel limit value calculation When the fuel injection amount limit value calculated by the means is exceeded, the ECU 30 or the like that limits and controls the amount of air supplied to the internal combustion engine 1 reaches the required fuel injection amount below the fuel injection amount limit value. Those comprising an air quantity control means being.
[0044]
That is, the maximum fuel injection amount that can be supplied at the present time is set as a fuel injection amount limit value according to various operating parameters of the internal combustion engine 1, and if the fuel injection amount limit value exceeds the required fuel injection amount, the capability of the fuel supply system Due to the shortage, the air-fuel ratio of the exhaust gas discharged from the internal combustion engine 1 becomes lean. Therefore, at this time, the amount of air supplied to the internal combustion engine 1 is controlled so that the required fuel injection amount falls below the fuel injection amount limit value. This makes it possible to control the air-fuel ratio of the exhaust gas discharged from the internal combustion engine 1 in the vicinity of the theoretical air-fuel ratio even when the fuel supply system becomes insufficient in capacity.
[0045]
Further, the fuel limit value calculating means achieved by the ECU 30 of the control device for an internal combustion engine of the above embodiment and the first to third modifications calculates the fuel injection amount limit value based on the battery voltage VB. Is. That is, as shown in FIG. 7, the fuel pump discharge amount of the fuel pump 12 varies with the battery voltage as a parameter. For this reason, an appropriate fuel injection amount limit value can be obtained by considering the current battery voltage.
[0046]
And the control apparatus for internal combustion engines of the said Example, a 1st modification, and a 2nd modification has a hysteresis characteristic in comparing the fuel injection amount limit value with the required fuel injection amount. That is, as shown in FIG. 3, when the required fuel injection amount exceeds the fuel injection amount limit value and shifts from the throttle normal control process to the throttle closing control process, the required fuel injection amount becomes equal to or less than the fuel injection amount limit value. When returning from the closing control process to the throttle normal control process, a predetermined value ΔH is provided as a hysteresis amount. Thereby, the stability of the control when the required fuel injection amount increases or decreases in the vicinity of the fuel injection amount limit value can be ensured.
[0047]
Further, the air amount control means of the control device for the internal combustion engine of the above embodiment and the first to third modifications is the throttle opening TA of the throttle valve 6 disposed in the intake passage 2 of the internal combustion engine 1. Is an electronic throttle control mechanism that can be changed via the electric motor 9 based on a control command value from the ECU 30. For this reason, in the internal combustion engine 1 equipped with the electronic throttle control mechanism, the driver request throttle opening is shown in FIG. As shown by the actual throttle opening degree with respect to the degree, the air amount restriction control of the internal combustion engine 1 is executed, so that the air-fuel ratio of the exhaust gas discharged from the internal combustion engine 1 is maintained in the vicinity of the theoretical air-fuel ratio. be able to.
[0048]
In addition, the air amount control means of the control device for an internal combustion engine according to the above-described embodiment and the first modified example is configured to supply the internal combustion engine 1 when the required fuel injection amount continuously exceeds the fuel injection amount limit value for a predetermined period or more. The air amount restriction control is started. That is, as shown at time t1 in FIG. 3, when the delay counter exceeds the predetermined value α, the ECU 30 starts the throttle closing control process as the restriction control of the air amount to the internal combustion engine 1. As a result, the air amount restriction control to the internal combustion engine 1 is controlled only when the required fuel injection amount surely exceeds the fuel injection amount limit value, and the transition from the throttle normal control processing to the throttle closing control processing is performed. Reliability can be improved.
[0049]
Further, the air amount control means of the control device for an internal combustion engine according to the above-described embodiment executes, stops, and repeats the re-execution and the sequential re-execution of the air amount to the internal combustion engine 1 for a shorter period than the predetermined period. Sometimes, the limit control is started as soon as the required fuel injection amount exceeds the fuel injection amount limit value. That is, the stop period is from time t2 to time t3 in FIG. 3, and the delay cancellation counter is set to “initial value (maximum value set in advance according to vehicle characteristics)” and then decremented to “0”. When the required fuel injection amount exceeds the fuel injection amount limit value, as shown at time t3 in FIG. 3, the throttle closing control processing is immediately performed from the throttle normal control processing by the ECU 30, as shown in time t3 in FIG. The restriction control of the amount of air supplied to is started. For this reason, when the restriction control of the air amount to the internal combustion engine 1 has been executed just recently, it is assumed that the fuel supply system has become insufficient in capacity and the required fuel injection amount exceeds the fuel injection amount limit value. Immediately, the control shifts to the restriction control of the air amount to the internal combustion engine 1. Thereby, it is possible to suppress the air-fuel ratio of the exhaust gas discharged from the internal combustion engine 1 from greatly deviating from the stoichiometric air-fuel ratio.
[0050]
By the way, in the above-described embodiment and the first to third modifications, the throttle closing control process for restricting and controlling the amount of air supplied to the internal combustion engine is performed in order to achieve the air amount control means. In the throttle closing control process, an electronic throttle control mechanism is used. However, the present invention is not limited to this, and a VVL (variable valve lifting control mechanism) 25 is used. Similarly, the amount of air supplied to the internal combustion engine can be limited and controlled, and the air-fuel ratio of the exhaust gas discharged from the internal combustion engine 1 can be maintained near the stoichiometric air-fuel ratio.
[0051]
Further, in the above-described embodiment and the first to third modifications, the fuel injection amount limit value is calculated based on the battery voltage as various operating parameters of the internal combustion engine. However, the present invention is not limited to this, and it is possible to construct a more practical system, for example, by considering the degree of deterioration of the fuel pump in the fuel supply system at that time and the fuel properties of the fuel used. Become.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an internal combustion engine to which an internal combustion engine control device according to an example of an embodiment of the present invention is applied and its peripheral devices.
FIG. 2 is a flowchart showing a processing procedure of throttle control in an ECU used in the control device for an internal combustion engine according to an example of the embodiment of the present invention.
FIG. 3 is a time chart showing transition states of various control amounts and the like corresponding to the processing of FIG. 2;
FIG. 4 is a flowchart showing a first modified example of a processing procedure of throttle control in the ECU used in the control device for an internal combustion engine according to an example of the embodiment of the present invention.
FIG. 5 is a flowchart showing a second modification of the processing procedure of throttle control in the ECU used in the control device for an internal combustion engine according to an example of the embodiment of the present invention;
FIG. 6 is a flowchart showing a third modification of the processing procedure of throttle control in the ECU used in the control device for an internal combustion engine according to one example of the embodiment of the invention.
FIG. 7 is a characteristic diagram showing a fuel pump discharge amount of a fuel pump in a fuel supply system of a general internal combustion engine before and after endurance using a battery voltage as a parameter.
[Explanation of symbols]
1 Internal combustion engine
2 Intake passage
6 Throttle valve
8 Injector (fuel injection valve)
9 Electric motor (actuator)
12 Fuel pump
13 Fuel pressure sensor
23 Intake valve
25 VVL (Variable valve lifting control mechanism)
30 ECU (Electronic Control Unit)

Claims (5)

Fuel supply means for supplying a fuel injection amount to the internal combustion engine;
A required fuel amount calculating means for calculating a required fuel injection amount required in the internal combustion engine;
Fuel limit value calculating means for calculating, as a fuel injection amount limit value, a maximum fuel injection amount that can be supplied at the present time by the fuel supply means in accordance with various operating parameters of the internal combustion engine;
When the required fuel injection amount calculated by the required fuel amount calculating means exceeds the fuel injection amount limit value calculated by the fuel limit value calculating means, the required fuel injection amount becomes equal to the fuel injection amount limit value. Air amount control means for limiting and controlling the amount of air supplied to the internal combustion engine to be less than,
When the required fuel injection amount exceeds the fuel injection amount limit value continuously for a predetermined period or more, the air amount control means starts control of limiting the air amount to the internal combustion engine, and sets the air amount to the internal combustion engine. When the stop period for executing, stopping, and sequentially repeating the limit control is shorter than a predetermined period, the limit control is started as soon as the required fuel injection amount exceeds the fuel injection amount limit value. A control device for an internal combustion engine. 2. The control apparatus for an internal combustion engine according to claim 1, wherein the fuel limit value calculating means calculates the fuel injection amount limit value based on at least an engine speed or a battery voltage of the internal combustion engine. The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the fuel injection amount limit value has a hysteresis characteristic when compared with the required fuel injection amount. 2. The electronic throttle control mechanism according to claim 1, wherein the air amount control means is an electronic throttle control mechanism capable of changing a throttle opening of a throttle valve disposed in an intake passage of the internal combustion engine via an actuator based on a control command value. 2. A control device for an internal combustion engine according to 1. 2. The internal combustion engine according to claim 1, wherein the air amount control means is a variable valve lifting control mechanism capable of changing a lift amount of an intake valve of the internal combustion engine via an actuator based on a control command value. Control device.

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