JP2019108824A - Fuel injection control apparatus - Google Patents

Abstract

To prevent an air-fuel mixture from becoming excessively rich in the case of injecting fuel using an in-cylinder injection valve in a state where a fuel injection amount is corrected so as to compensate for fuel attached to a port wall surface.SOLUTION: A fuel injection control apparatus includes: a start-time fuel injection control part for performing fuel injection using an in-cylinder injection valve in the case of restarting an internal combustion engine by S&S control; a fuel injection valve selection part for selecting a fuel injection valve to be used for fuel injection after the restart; a port injection correction factor calculation part for calculating a port injection correction factor for compensating for an amount that is attached to a wall surface in a port injection amount when fuel is injected by a port injection valve; and a fuel injection amount calculation part for correcting a fuel injection amount by an attenuation factor that attenuates the port injection correction factor, in a case where the fuel injection valve selection part has selected the in-cylinder injection valve, in a state where the fuel injection valve selection part selects the port injection valve, with the fuel injection amount corrected on the basis of the port injection correction factor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel injection control device.

  An internal combustion engine is conventionally known that includes a port injection valve that injects fuel into an intake passage (port) of the internal combustion engine, and an in-cylinder injection valve that injects fuel into a cylinder of the internal combustion engine. In such an internal combustion engine, start-up injection control is performed using an in-cylinder injection valve, and then post-start fuel injection control is performed using a fuel injection valve selected from the in-cylinder injection valve and the port injection valve. (See, for example, Patent Document 1).

JP, 2010-255507, A

  By the way, when fuel injection is performed by the port injection valve, fuel may adhere mainly to the port wall surface. When fuel adheres to the port wall surface, the amount of fuel actually supplied to combustion decreases. For this reason, when fuel injection is performed by the port injection valve, the fuel injection amount corrected to compensate for the amount of fuel attached to the port wall surface is injected. On the other hand, when fuel injection is performed by the in-cylinder injection valve, blowback from the combustion chamber may occur. The fuel injection amount corrected to compensate for the fuel adhering to the port wall surface is injected, and if the unburned fuel is included in the blowback, the air-fuel mixture becomes over-rich and the combustion failure and fuel efficiency deterioration It may occur.

  Therefore, in the fuel injection control device disclosed in the present specification, when fuel injection by the in-cylinder injection valve is performed in a state in which the fuel injection amount is corrected so as to compensate the fuel adhering to the port wall surface The task is to avoid the rich state.

  The fuel injection control device disclosed in the present specification performs automatic stop / restart control for automatically stopping the internal combustion engine when a predetermined automatic stop condition is satisfied, and for restarting the internal combustion engine when a predetermined restart condition is satisfied. A fuel injection control device for an internal combustion engine comprising a port injection valve mounted on a vehicle and injecting fuel into an intake passage, and an in-cylinder injection valve injecting fuel into a cylinder, wherein the internal combustion engine is restarted When the fuel injection control is performed, the fuel injection control unit at start-up that performs fuel injection by the in-cylinder injection valve, the fuel injection valve selection unit that selects the fuel injection valve used in fuel injection after the restart, and the port injection valve A port injection correction coefficient calculation unit that calculates a port injection correction coefficient that compensates for the amount of fuel attached to the wall surface in the port injection amount when performing fuel injection by the fuel injection valve; When the in-cylinder injection valve is selected by the fuel injection valve selection unit in a state where the fuel injection amount is corrected by the port injection correction coefficient, the port injection correction coefficient is attenuated. And a fuel injection amount calculating unit that corrects the fuel injection amount by the attenuation coefficient.

  According to the fuel injection control device disclosed in the present specification, when the fuel injection by the in-cylinder injection valve is performed in a state where the fuel injection amount is corrected so as to compensate the fuel adhering to the port wall surface Rich conditions can be avoided.

FIG. 1 is a schematic configuration diagram of an internal combustion engine system provided with a fuel injection control device of the embodiment. FIG. 2 is a flowchart showing an example of control performed by the fuel injection control device of the embodiment. FIG. 3 is a graph showing an example of a time change of an execution correction coefficient C, an engine rotational speed Ne, and a starter signal according to the control performed by the fuel injection control device of the embodiment. FIG. 4 is an example of a map for determining an initial correction coefficient A used by the fuel injection control device of the embodiment. FIG. 5: is an example of the map for selecting the fuel injection valve which the fuel-injection control apparatus of embodiment uses.

  Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. However, in the drawings, the dimensions, proportions, etc. of each part may not be illustrated so as to completely correspond to the actual ones. Also, some drawings may be drawn with details omitted.

(Embodiment)
FIG. 1 is a schematic block diagram of an internal combustion engine system 1. The internal combustion engine 20 burns the air-fuel mixture in a combustion chamber 23 in a cylinder head 22 installed on a cylinder block 21 in which a piston 24 is housed, and causes the piston 24 to reciprocate. The reciprocating motion of the piston 24 is converted to the rotational motion of the crankshaft 26. The internal combustion engine 20 of the present embodiment is an in-line four-cylinder internal combustion engine, but is not limited thereto.

  In the cylinder head 22 of the internal combustion engine 20, an intake valve Vi for opening and closing the intake port 10i and an exhaust valve Ve for opening and closing the exhaust port 30e are provided for each cylinder. Further, at the top of the cylinder head 22, an ignition plug 27 for igniting the mixture in the combustion chamber 23 is attached to each cylinder. The intake port 10i is included in the intake passage.

  The intake port 10i of each cylinder is connected to the surge tank 18 via a branch pipe for each cylinder. An intake pipe 10 is connected to the upstream side of the surge tank 18, and an air cleaner 19 is provided at the upstream end of the intake pipe 10. An air flow meter 15 for detecting the amount of intake air and an electronically controlled throttle valve 13 are provided in the intake pipe 10 sequentially from the upstream side.

  Further, at the intake port 10i of each cylinder, a port injection valve 12p for injecting fuel into the intake port 10i is installed. Further, in each cylinder, an in-cylinder injection valve 12d for injecting fuel into the cylinder is installed. The fuel injected from these injection valves is mixed with the intake air to form an air-fuel mixture, and this air-fuel mixture is drawn into the combustion chamber 23 when the intake valve Vi is opened, compressed by the piston 24, and ignited by the ignition plug 27. It is done.

  The exhaust port 30e of each cylinder is connected to the exhaust pipe 30 via a branch pipe for each cylinder. The exhaust pipe 30 is provided with a three-way catalyst 31. An air-fuel ratio sensor 33 for detecting the air-fuel ratio of the exhaust gas is disposed upstream of the three-way catalyst 31.

The internal combustion engine system 1 includes an ECU (Electronic Control Unit) 50. The ECU 50 includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a storage device, and the like. The ECU 50 controls the internal combustion engine 20 by executing a program stored in the ROM or the storage device.
The programs stored in the storage device include programs for performing S & S (Stop & Start) control and calculating the fuel injection amount. The ECU 50 functions as a fuel injection control device of the internal combustion engine 20, and executes control described later. This control is realized by the start time fuel injection control unit, the port injection correction coefficient calculation unit, the fuel injection valve selection unit, and the fuel injection amount calculation unit which are functionally realized by the CPU, the ROM, and the RAM. Details will be described later.

  The ignition plug 27, the throttle valve 13, the port injection valve 12p, the in-cylinder injection valve 12d, and the like are electrically connected to the ECU 50. The ECU 50 also includes an accelerator opening sensor 11 for detecting the accelerator opening, a throttle opening sensor 14 for detecting the throttle opening of the throttle valve 13, an air flow meter 15 for detecting the amount of intake air, an air-fuel ratio sensor 33, and a crankshaft. A crank angle sensor 25 for detecting the crank angle 26, a water temperature sensor 29 for detecting the temperature of cooling water of the internal combustion engine 20, and other various sensors are electrically connected. The ECU 50 controls the spark plug 27, the throttle valve 13, the port injection valve 12p, the in-cylinder injection valve 12d, and the like so as to obtain a desired output based on detection values of various sensors, etc. Control the amount, fuel injection ratio, fuel injection timing, throttle opening and so on.

The ECU 50 performs S & S (Stop & Start) control. The ECU 50 that performs S & S control determines whether the automatic stop condition of the internal combustion engine 20 is met. The automatic stop condition is satisfied, for example, when all the following conditions (a) to (d) are satisfied.
Condition (a): The vehicle speed of the host vehicle is equal to or less than a predetermined vehicle speed (≧ 0).
Condition (b): The accelerator pedal is not depressed.
Condition (c): The brake booster negative pressure value is on the vacuum side of a predetermined threshold.
Condition (d): The brake pedal is depressed.
In addition, conditions (a)-(d) are an example, and can be changed suitably.

  The ECU 50 stops fuel injection and stops the internal combustion engine 20 when the automatic stop condition is satisfied. When the fuel injection is performed by the port injection valve 12p when the internal combustion engine 20 is in operation, the fuel adheres to the wall surface of the intake port 10i, but when the fuel injection is stopped, the wall surface of the intake port 10i The deposited fuel evaporates.

The ECU 50 determines whether the restart condition of the internal combustion engine 20 is met. The restart condition is satisfied, for example, when one of the following conditions (e) to (g) is not satisfied.
Condition (e): The vehicle speed of the host vehicle is equal to or less than a predetermined vehicle speed (≧ 0).
Condition (f): The brake pedal is depressed.
Condition (g): The brake booster negative pressure value is on the vacuum side of a predetermined threshold.
In addition, conditions (e)-(g) are an example and can be changed suitably.

  The ECU 50 performs start-up fuel injection control when the restart condition is satisfied. In start-up injection control, fuel injection using the in-cylinder injection valve 12d is performed from the viewpoint of reduction of PM (Particulate Matter) and securing of early startability.

  The ECU 50 performs post-startup fuel injection control after the internal combustion engine 20 is started by the start-up fuel injection control. In post-start fuel injection control, the fuel injection valve to be used is selected in consideration of the load and the like in the internal combustion engine 20. The fuel injection valve to be used is divided into an injection mode using only the port injection valve 12p, an injection mode using both the port injection valve 12p and the in-cylinder injection valve 12d, and an injection mode using only the in-cylinder injection valve 12d. .

  Here, when the port injection valve 12p is used, the fuel injection amount is corrected so as to compensate for the fuel adhering to the wall surface of the intake port 10i. At this time, the ECU 50 calculates a port injection correction coefficient that supplements the amount of fuel attached to the wall surface in the port injection amount. The port injection correction coefficient A is A> 1.

  When the fuel injection amount is corrected by the port injection correction coefficient after restart by S & S control, the fuel injection amount is in a state of being increased more than the fuel injection amount to be the base calculated from the intake air amount etc. . When the fuel injection amount is increased as described above, the fuel injection is performed using the in-cylinder injection valve 12d, and if the blow back occurs, the air-fuel mixture becomes rich. Therefore, the fuel injection amount is calculated by further correcting the fuel injection amount with the attenuation coefficient B that attenuates the port injection correction coefficient A.

  Hereinafter, an example of a specific fuel injection control will be described with reference to FIGS. 2 to 5. First, in step S1, the ECU 50 determines whether the internal combustion engine 20 has been restarted by S & S control. The restart of the internal combustion engine 20 is satisfied when at least one of the above-mentioned conditions (e) to (g) is not satisfied, and the YES determination is made. When it is judged as NO by step S1, the process of step S1 is repeated until it is judged as YES by step S1. If YES is determined in step S1, the process proceeds to step S2.

  In step S2, the ECU 50 acquires the water temperature and the time when the internal combustion engine 20 has been stopped by the S & S control. Then, the ECU 50 calculates the port injection correction coefficient A in step S3 and sets the port injection correction coefficient A to the execution correction coefficient C at this stage. The execution correction coefficient C is a correction coefficient for correcting the fuel injection amount serving as the base and calculating the final injection amount to be actually injected. The ECU 50 further turns on the starter signal.

  Here, the calculation of the port injection correction coefficient A will be described with reference to FIG. The port injection correction coefficient A is calculated based on the water temperature acquired in step S2 and the time during which the internal combustion engine 20 has been stopped by the S & S control. The port injection correction coefficient A increases as the stop time increases, and decreases as the water temperature increases. This is because, as the stop time is longer, the combustion evaporates from the wall surface of the intake port 10i and becomes dry, and the amount of fuel adhering to the wall surface increases when fuel injection is performed by the port injection valve 12p thereafter. It is. In addition, the higher the water temperature, the better the fuel is atomized, and the smaller the amount of fuel adhering to the wall surface when fuel injection is performed by the port injection valve 12p.

  In step S4, the ECU 50 determines whether the number of start injections has been eight or more. Here, the number of start injections is the number of injections by the in-cylinder injection valve 12d as the fuel injection at the start. Since the internal combustion engine 20 of the present embodiment is a four-cylinder internal combustion engine, the ECU 50 determines that the internal combustion engine 20 has started when fuel injection is performed twice for each cylinder. Note that such a determination is an example of the determination as to whether or not the fuel injection at start has been completed, and may be determined by another determination method. For example, when the number of revolutions of the internal combustion engine 20 (the number of engine revolutions Ne) becomes equal to or more than a predetermined number of revolutions, it may be determined that the start fuel injection has been completed.

  When the ECU 50 determines NO in step S4, the process proceeds to step S5. In step S5, a start injection amount is calculated. The start-up fuel injection is performed by the in-cylinder injection valve 12 d and is not affected by the fuel injection by the port injection valve 12 p after restart, so the start injection amount is the port injection correction coefficient A Determined independently. The start injection amount is calculated based on, for example, a map of the start fuel injection amount associated with the water temperature.

  In step S6, which is performed subsequent to step S5, start injection is performed. When the start injection is performed, the engine speed Ne increases as shown in FIG. After step S6 is executed, the ECU 50 executes step S4 again.

  If it is determined YES in step S4, the ECU 50 proceeds to step S7. The injection control after step S7 is fuel injection control after start. In step S7, the ECU 50 determines whether fuel injection by the port injection valve 12p has been performed. Specifically, it is determined whether the port injection valve 12p is selected as the fuel injection valve used after the internal combustion engine 20 is restarted. The selection of the fuel injection valve is performed, for example, using the map shown in FIG. Referring to FIG. 5, when the air amount (load) and the engine rotational speed Ne are low, fuel injection is performed by the port injection valve 12p. Further, when the air amount (load) and the engine rotational speed Ne are respectively medium, fuel injection is performed using both the port injection valve 12p and the in-cylinder injection valve 12d. Further, when the air amount (load) and the engine rotational speed Ne are high, fuel injection is performed by the in-cylinder injection valve 12d.

  When fuel injection only by the port injection valve 12p and fuel injection by the port injection valve 12p and the in-cylinder injection valve 12d are performed, the ECU 50 determines YES in step S7. If it is determined YES in step S7, the process proceeds to step S8.

  In step S8, the ECU 50 determines whether fuel injection using the port injection valve 12p has been performed a number of times greater than the number of cylinders after restart. Since the internal combustion engine 20 of this embodiment has four cylinders, it is determined whether fuel injection using the port injection valve 12p has been performed four times. This is to determine whether fuel adheres to the wall surface of each intake port 10i after the restart.

  When it is determined as YES in step S8, the process proceeds to step S9, the ECU 50 sets the final fuel injection amount to base, and executes fuel injection in step S10. Once fuel adheres to the wall surfaces of intake ports 10i of all cylinders, even if fuel injection is subsequently performed by port injection valve 12p, basically no further adhesion of the fuel wall surface occurs, and the fuel is used for combustion. There is no need to reduce fuel consumption.

  On the other hand, when it determines with NO by step S7, it progresses to step S11. In step S11, the ECU 50 determines whether a correction request has been made after restart by S & S control. That is, fuel injection using the port injection valve 12p is performed after restart, and it is determined whether or not the final fuel injection amount is corrected by the port injection correction coefficient A. If it is determined NO in step S11, fuel injection using port injection valve 12p is not yet performed after restart, and fuel injection using port injection valve 12p is not performed at this stage as well. . Therefore, when it is determined NO in step S11, the process proceeds to step S9, the final fuel injection amount is set to base, and fuel injection is performed in step S10.

  If it is determined YES in step S11, the process proceeds to step S12, the attenuation coefficient B is multiplied by the already set execution correction coefficient C, and the new execution correction coefficient C is updated and stored. The execution correction coefficient C stored here is used in step S13 of determining the final injection amount via step S8. Here, the damping coefficient B is B <1, and in this embodiment, B is set to 0.9. By multiplying the damping coefficient B, the value of the actual correction coefficient C becomes smaller. As a result, the final injection amount is reduced, and thus the mixture rich state is improved. The damping coefficient B can not take 0 or 1 because of the property of damping the port injection correction coefficient A, and is appropriately set within the range of 0.1 to 0.99.

  After the execution correction coefficient C is updated in step S12, the final injection amount is set to base in step S9. Then, fuel injection is performed in step S10. Also when the execution correction coefficient C is updated in step S12, NO is determined in step S7, and fuel injection using the port injection valve 12p is not performed. Therefore, when it is determined NO in step S11, the process proceeds to step S9, the final fuel injection amount is set to base, and fuel injection is performed in step S10.

  If NO in step S8, the final injection amount is set to base × C in step S13, and fuel injection is performed in step S10. Here, the execution correction coefficient C differs depending on whether or not it passes through step S12. When step S12 is not performed, the execution correction coefficient C remains the port injection correction coefficient A, which is an initial value, as A = C is set in step S3. On the other hand, when passing through step S12, the attenuation coefficient B is a multiplied value. When the process goes through step S12 a plurality of times, the value of the execution correction coefficient C decreases by that amount.

  After the injection is performed in step S10, the process proceeds to step S14. In step S14, it is determined again whether or not there is a stop due to the S & S control. When the determination in step S14 is NO, the ECU 50 repeats the process from step S7. As described above, the process from step S7 is repeated, and when the process goes through step S12 a plurality of times, the execution correction coefficient C gradually decreases as shown in FIG. As a result, the final injection amount is further reduced, and the richness of the mixture is further improved. However, 1 is set as a guard value so that the execution correction coefficient C does not become smaller than 1.

  When it is determined as YES in step S14, the series of processing is returned, and the processing from step S1 is repeated.

  Thus, by introducing the damping coefficient B for attenuating the port injection correction coefficient A, it is possible to avoid an air-fuel mixture rich state. As a result, combustion defects and fuel efficiency deterioration in the internal combustion engine 20 can be improved.

  The above embodiments are merely examples for carrying out the present invention, and the present invention is not limited to these, and various modifications of these examples are within the scope of the present invention, and further, the present invention. It is obvious from the above description that within the scope various other embodiments are possible.

1 internal combustion engine system 10i intake port 12p port injection valve 12d in-cylinder injection valve 20 internal combustion engine 50 ECU (fuel injection control device, fuel injection control unit at start-up, port injection correction coefficient calculation unit, fuel injection valve selection unit and fuel injection amount Calculation unit)

Claims (1)

When the predetermined automatic stop condition is satisfied, the internal combustion engine is automatically stopped. On the other hand, when the predetermined restart condition is satisfied, the internal combustion engine is restarted. A fuel injection control device for an internal combustion engine, comprising: a port injection valve; and an in-cylinder injection valve that injects fuel into a cylinder,
A start-up fuel injection control unit that performs fuel injection by the in-cylinder injection valve when restarting the internal combustion engine;
A fuel injection valve selection unit for selecting a fuel injection valve used in fuel injection after the restart;
A port injection correction coefficient calculation unit that calculates a port injection correction coefficient that complements the amount of fuel attached to the wall surface in the port injection amount when fuel injection is performed by the port injection valve;
When the in-cylinder injection valve is selected by the fuel injection valve selection unit in a state where the port injection valve is selected by the fuel injection valve selection unit and the fuel injection amount is corrected by the port injection correction coefficient, A fuel injection amount calculation unit that corrects a fuel injection amount by an attenuation coefficient that attenuates the port injection correction coefficient;
Fuel injection control device equipped with

Images