JP2007239487A - Fuel supply control device for internal combustion engine - Google Patents

Abstract

A fuel injection amount at the time of resumption of a fuel injection operation is made to exactly match a normal amount.
A port injection valve 18p for injecting fuel into an intake port 7 and a cylinder injection valve 18d for injecting fuel directly into the cylinder are provided. Depending on the engine load, the fuel injection action from the port injection valve 18p or the fuel injection action from the in-cylinder injection valve 18d is stopped. For the fuel injection valve in which the fuel injection action is stopped, the temperature change amount of the fuel injection valve itself or the fuel in the fuel injection valve that occurs from when the fuel injection action is stopped until it is restarted is estimated, and the fuel injection action is restarted The fuel injection amount is corrected based on the estimated temperature change amount.
[Selection] Figure 1

Description

  The present invention relates to a fuel supply control device for an internal combustion engine.

  An intake passage fuel injection valve for injecting fuel into the engine intake passage and an in-cylinder fuel injection valve for injecting fuel directly into the cylinder are provided. An internal combustion engine that performs fuel injection from a cylinder fuel injection valve while stopping fuel injection and performs fuel injection from an intake passage fuel injection valve and cylinder fuel injection valve during high engine load operation is known (See Patent Document 1). In this internal combustion engine, an air-fuel mixture is formed only in a limited region in the combustion chamber during engine low-load operation, and the combustion chamber is filled with a substantially uniform air-fuel mixture during engine high-load operation.

Japanese Patent Laid-Open No. 10-176574

  In the above-described internal combustion engine, when the engine load becomes low, the fuel injection action from the intake passage fuel injection valve is stopped, and then when the engine load becomes high, the fuel injection action from the intake passage fuel injection valve is resumed. Thus, while the fuel injection action is stopped, the temperature of the fuel in the intake passage fuel injection valve may rise due to, for example, receiving heat from the cylinder head. In this case, the fuel in the intake passage fuel injection valve expands, or the intake passage fuel injection valve itself expands to reduce the internal fuel passage cross-sectional area. As a result, the fuel is actually injected from the intake passage fuel injection valve. There is a risk that the amount of fuel will be less than the normal amount.

  In order to solve the above problems, according to the present invention, in an internal combustion engine that includes a fuel injection valve and stops the fuel injection action from the fuel injection valve during engine operation, the fuel injection action is resumed after the fuel injection action is stopped. The amount of change in the temperature of the fuel injection valve itself or the fuel in the fuel injection valve is estimated, and the amount of fuel injection is corrected based on the estimated amount of change in temperature when the fuel injection operation is resumed.

  It is possible to accurately match the fuel injection amount when the fuel injection operation is resumed with the regular amount.

  FIG. 1 shows a case where the present invention is applied to a spark ignition type internal combustion engine. However, the present invention can also be applied to a compression ignition type internal combustion engine.

  Referring to FIG. 1, for example, 1 is an engine body having four cylinders, 2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is an intake valve, 7 is an intake port, and 8 is an exhaust. A valve, 9 is an exhaust port, and 10 is a spark plug. The intake port 7 is connected to a surge tank 12 via a corresponding intake branch pipe 11, and the surge tank 12 is connected to an air cleaner 14 via an intake duct 13. A throttle valve 16 driven by a step motor 15 is disposed in the intake duct 13. An air flow meter 17 for detecting the intake air mass flow rate Ga is mounted in the intake duct 13 upstream of the throttle valve 16.

  Each cylinder has an electrically controlled fuel injection valve 18p (hereinafter referred to as a port injection valve) disposed in the intake port 7 and an electrically controlled fuel injection valve 18d (hereinafter referred to as a cylinder) disposed in the combustion chamber 5. (Referred to as an internal injection valve). The port injection valve 18p is connected to the fuel tank 21 via a fuel pressure accumulating chamber or common rail 19p and an electronically controlled variable discharge fuel pump 20p. The cylinder injection valve 18d is connected to the fuel pressure accumulating chamber or common rail 19d and electronically controlled. It is connected to the fuel tank 21 via a fuel pump 20d having a variable discharge amount. Further, the common rails 19p and 19d are connected to the fuel tank 21 by corresponding return passages (not shown). The fuel in the fuel tank 21 is supplied from the fuel pumps 20p and 20d into the corresponding common rails 19p and 19d, and is supplied from the common rails 19p and 19d to the corresponding port injection valve 18p and in-cylinder injection valve 18d. Fuel pressure sensors (not shown) for detecting the fuel pressure in the common rails 19p and 19d are respectively attached to the common rails 19p and 19d, and the fuel pressures in the common rails 19p and 19d, that is, the fuels, are based on the output signals of the fuel pressure sensors. The discharge amounts of the corresponding fuel pumps 20p and 20d are controlled so that the injection rate matches the target value. Furthermore, a fuel temperature sensor 22 for detecting the temperature Tf of the fuel in the fuel tank 21 is attached to the fuel tank 21.

  On the other hand, the exhaust port 9 is connected to an exhaust pipe 24 via an exhaust manifold 23, and a small capacity catalyst 25 and a large capacity catalyst 26 are arranged in the exhaust pipe 24 in order from the upstream side. For example, an air-fuel ratio sensor or oxygen concentration sensors 27 and 28 for detecting the air-fuel ratio are attached to the exhaust manifold 23 and the exhaust pipe 24 between the catalysts 25 and 26, respectively.

  The electronic control unit 30 is composed of a digital computer, and is connected to each other by a bidirectional bus 31. A ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a CPU (Microprocessor) 34, an input port 35 and an output port 36. It comprises. A water temperature sensor 39 for detecting the engine cooling water temperature thw is attached to the engine body 1. Further, a load sensor 41 for detecting the depression amount L of the accelerator pedal 40 is connected to the accelerator pedal 40. The depression amount L of the accelerator pedal 40 represents a required load. The output signals of the air flow meter 17, the fuel temperature sensor 22, the air-fuel ratio sensors 27 and 28, and the load sensor 41 are input to the input port 35 via corresponding AD converters 37, respectively. Further, a crank angle sensor 42 that generates an output pulse every time the crankshaft rotates, for example, 30 °, and a vehicle speed sensor 43 that generates an output pulse representing the vehicle speed SPD are connected to the input port 35. The CPU 34 calculates the engine speed Ne based on the output pulse of the crank angle sensor 42. On the other hand, the output port 36 is connected to the spark plug 10, the step motor 15, the fuel injection valves 18 p and 18 d, and the fuel pumps 20 p and 20 d via corresponding drive circuits 38, which are output signals from the electronic control unit 30. Controlled based on.

  FIG. 2 shows an example of fuel injection control in the internal combustion engine shown in FIG. That is, when the engine load L is lower than the predetermined set load LX, fuel is injected from the in-cylinder injection valve 18d while stopping the fuel injection action from the port injection valve 18p. Thereby, an air-fuel mixture is formed in the combustion chamber 5, and this air-fuel mixture is then ignited by the spark plug 10. Note that the target air-fuel ratio at this time is set to a lean air-fuel ratio or a stoichiometric air-fuel ratio. In contrast, when the engine load L is higher than the set load LX, fuel is injected from the port injection valve 18p while stopping the fuel injection action from the in-cylinder injection valve 18d. As a result, an air-fuel mixture that fills the combustion chamber 5 substantially uniformly is formed, and this air-fuel mixture is then ignited by the spark plug 10. The target air-fuel ratio at this time is set to a lean air-fuel ratio or a stoichiometric air-fuel ratio.

  Therefore, after the engine load L becomes smaller than the set load LX, the fuel injection action from the port injector 18p is stopped until the engine load L becomes larger than the set load LX again, and the engine load L becomes larger than the set load LX. The fuel injection action from the in-cylinder injection valve 18d is stopped until it becomes smaller. In either case, the fuel injection action is stopped for a period exceeding one combustion cycle.

  When the engine load L increases beyond the set load or decreases, the fuel injection action of both the port injection valve 18p and the in-cylinder injection valve 18d may be performed.

  In the embodiment according to the present invention, the port injection amount PQ that is the fuel injection amount in the port injection valve 18p and the in-cylinder injection amount DQ that is the fuel injection amount in the in-cylinder injection valve 18d are respectively calculated by the following equations.

PQ = PQB ・ Kp ・ KpC
DQ = DQB ・ Kd ・ KdC
Here, PQB, Kp, and KpC are the basic fuel injection amount for the port injection valve 18p, the restart correction coefficient, and other correction coefficients, and DQB, Kd, and KdC are the basic fuel injection amount for the in-cylinder injection valve 18d and the restart. The hour correction coefficient and other correction coefficients are shown respectively.

  The basic fuel injection amounts PQB and DQB are fuel amounts required to make the air-fuel ratios coincide with the corresponding target air-fuel ratios. The other correction coefficients KpC and KdC collectively represent the air-fuel ratio correction coefficient, the acceleration increase correction coefficient, etc., and are set to 1.0 when there is no need for correction.

  The restart correction coefficients Kp and Kd are for making the actual fuel injection amount coincide with the normal injection amount when the fuel injection operation is restarted after being stopped, and are 1.0 when no correction is required. It is said.

  First, the restart correction coefficients Kp and Kd will be schematically described. For example, when the engine load L becomes lower than the set load LX and the fuel injection action from the port injection valve 18p is stopped, the internal fuel existing in the fuel passage in the port injection valve 18p at this time is the fuel injection action. Is stopped by the fuel in the port injection valve 18p itself or the common rail 19p. As a result, the temperature of the internal fuel gradually increases and the internal fuel expands. Further, the temperature of the port injection valve 18p itself rises while the fuel injection operation is stopped, and as a result, the flow passage cross-sectional area of the fuel passage in the port injection valve 18p decreases. As a result, when the port injection valve 18p is opened for a time corresponding to the above-described PQB · KpC when the fuel injection operation is resumed, the actual fuel amount becomes smaller than the normal fuel amount. The amount of fuel decrease in this case depends on the temperature of the port injection valve 18p itself or the fuel in the port injection valve 18p when the fuel injection operation is restarted, and this is a port that occurs between when the fuel injection operation is stopped and when it is restarted. It depends on the fuel temperature change amount in the injection valve 18p itself or in the port injection valve 18p.

  Therefore, in the embodiment according to the present invention, the correction coefficient Kp at the time of restart that is determined in accordance with the temperature change amount of the port injection valve 18p itself or its internal fuel generated from when the fuel injection action from the port injection valve 18p is stopped to when it is restarted. Is introduced, and PQB · KpC is corrected with the correction coefficient Kp at the time of restart.

  That is, when the fuel injection action from the port injector 18p is stopped as indicated by the arrow t1 in FIG. 3, the restart correction coefficient Kp for the port injector 18p increases from 1.0. Next, when the fuel injection action from the port injection valve 18p is restarted as indicated by an arrow t2 in FIG. 3, the above-described PQB · KpC is corrected by the restart correction coefficient Kp. As a result, the actual fuel injection amount can be exactly matched to the normal injection amount when the fuel injection operation is resumed.

  When the fuel injection operation is resumed, the temperature of the port injection valve 18p itself or its internal fuel gradually decreases due to the cooling operation of the fuel flowing through the port injection valve 18p. Therefore, in the embodiment according to the present invention, the restart correction coefficient Kp is decreased by the amount of attenuation ΔKp. This attenuation amount ΔKp may be a constant value or may be determined according to the fuel temperature Tf, for example. When the restart correction coefficient Kp decreases to 1.0, it is maintained at 1.0 thereafter.

  The restart correction coefficient Kp for the port injection valve 18p is calculated by the following equation.

Kp = Kpt + Kpb + Kpf
Here, Kpt represents a tip correction coefficient, Kpb represents a main body correction coefficient, and Kpf represents a fuel correction coefficient.

  The front end correction coefficient Kpt increases as the amount of temperature change at the front end of the port injection valve 18p that occurs from when the fuel injection from the port injection valve 18p is stopped until it is restarted increases. Here, assuming that the temperature at the tip of the port injection valve 18p changes by ΔPTt per unit time while the fuel injection operation from the port injection valve 18p is stopped, the fuel injection operation from the port injection valve 18p is stopped. The amount of temperature change at the tip of the port injection valve 18p that occurs until the restart is represented by Σ (ΔPTt). Therefore, the tip correction coefficient Kpt increases as the temperature change amount Σ (ΔPTt) at the tip of the port injection valve 18p increases as shown in FIG.

  Similarly, the main body correction coefficient Kpb and the fuel correction coefficient Kpf are respectively increased when the temperature change amount of the main body of the port injection valve 18p and the internal fuel generated between the stop and restart of the fuel injection operation from the port injection valve 18p increases. It will be bigger. Here, assuming that the temperature of the main body of the port injection valve 18p and the internal fuel change by ΔPTb and ΔPTf per unit time while the fuel injection operation from the port injection valve 18p is stopped, the fuel injection operation from the port injection valve 18p. The change in temperature of the main body of the port injector 18p and the internal fuel that occurs from when the engine is stopped to when it is restarted is represented by Σ (ΔPTb) and Σ (ΔPTf), respectively. Therefore, the main body correction coefficient Kpb and the fuel correction coefficient Kpf are the temperature change amounts Σ (ΔPTt) and Σ (ΔPtf) of the main body and the internal fuel of the port injector 18p, as shown in FIGS. 4B and 4C, respectively. Increases as each increases.

  The temperature change amount ΔPTt per unit time at the tip of the port injection valve 18p while the fuel injection action from the port injection valve 18p is stopped is calculated by the following equation.

ΔPTt = kthw1 + kair + kf1
kthw1 represents the temperature change at the tip of the port injection valve 18p by the engine main body 1, and increases as the engine coolant temperature thw increases as shown in FIG. 5 (A). Kair represents the temperature change at the tip of the port injection valve 18p due to the air flowing through the intake port 7, and decreases as the intake air amount Ga increases as shown in FIG. kf1 represents the temperature change at the tip of the port injection valve 18p due to the fuel supplied into the common rail 19p, and increases as the fuel temperature Tf in the fuel tank 21 increases as shown in FIG. 5C. .

  On the other hand, the temperature change amount ΔPTb per unit time of the main body of the port injection valve 18p while the fuel injection action from the port injection valve 18p is stopped is calculated by the following equation.

ΔPTb = kthw2 + kspd1 + kf2
kthw2 represents a temperature change of the main body of the port injection valve 18p by the engine main body 1, and increases as the engine cooling water temperature thw becomes higher as shown in FIG. kspd1 represents the temperature change of the main body of the port injection valve 18p due to the vehicle running wind, and decreases as the vehicle speed SPD increases as shown in FIG. kf2 represents the temperature change at the tip of the port injection valve 18p due to the fuel supplied into the common rail 19p, and increases as the fuel temperature Tf in the fuel tank 21 increases as shown in FIG. 5 (F). .

  The temperature change amount ΔPTf per unit time of the internal fuel of the port injection valve 18p while the fuel injection action from the port injection valve 18p is stopped is calculated by the following equation.

ΔPTf = kthw3 + kspd2
kthw3 represents the temperature change of the internal fuel of the port injector 18p by the engine body 1, and increases as the engine coolant temperature thw increases as shown in FIG. 5 (G). kspd2 represents the temperature change of the internal fuel of the port injection valve 18p due to the vehicle traveling wind, and decreases as the vehicle speed SPD increases as shown in FIG. 5 (H).

  That is, when the fuel injection action from the port injection valve 18p is stopped, ΔPTt, ΔPTb, ΔPTf are calculated, and their integrated values Σ (ΔPTt), Σ (ΔPTb), Σ (ΔPTf) are calculated. . When the fuel injection action from the port injection valve 18p is to be resumed, Kpt, Kpb, Kpf are calculated from the integrated values Σ (ΔPTt), Σ (ΔPTb), and Σ (ΔPTf) at this time, respectively, and the resumption correction coefficient Kp is Calculated.

  Similarly, the restart correction coefficient Kd is determined in accordance with the temperature change amount of the in-cylinder injection valve 18d itself or its internal fuel that is generated after the fuel injection action from the in-cylinder injection valve 18d is stopped and restarted. That is, as shown by the arrow t2 in FIG. 3, when the fuel injection action from the in-cylinder injection valve 18d is stopped, the restart correction coefficient Kd for the in-cylinder injection valve 18d increases from 1.0. Next, when the fuel injection action from the in-cylinder injection valve 18d is restarted as indicated by an arrow t3 in FIG. 3, the above-described DQB · KdC is corrected by the restart correction coefficient Kd. Next, the restart correction coefficient Kd is gradually decreased toward 1.0 with the amount of attenuation ΔKd.

  The restart correction coefficient Kd for the in-cylinder injection valve 18d is calculated by the following equation.

Kd = Kdt + Kdb + Kdf
Here, Kdt represents a tip correction coefficient, Kdb represents a main body correction coefficient, and Kdf represents a fuel correction coefficient.

  The front end correction coefficient Kdt increases as the amount of temperature change at the front end of the in-cylinder injection valve 18d that occurs from when the fuel injection operation from the in-cylinder injection valve 18d is stopped to when it is restarted increases. Here, assuming that the temperature at the tip of the in-cylinder injection valve 18d changes by ΔDTt per unit time while the fuel injection operation from the in-cylinder injection valve 18d is stopped, the fuel injection operation from the in-cylinder injection valve 18d stops. The amount of temperature change at the tip of the in-cylinder injection valve 18d that occurs from when it is restarted is represented by Σ (ΔDTt). Therefore, the tip correction coefficient Kdt increases as the temperature change amount Σ (ΔDTt) at the tip of the in-cylinder injection valve 18d increases as shown in FIG.

  Similarly, the main body correction coefficient Kdb and the fuel correction coefficient Kdf are large in the amount of temperature change of the main body of the in-cylinder injection valve 18d and the internal fuel that occurs between when the fuel injection action from the in-cylinder injection valve 18d is stopped and restarted. It will become bigger each time. Here, assuming that the temperature of the main body of the in-cylinder injection valve 18d and the internal fuel change by ΔDTb and ΔDTf per unit time while the fuel injection operation from the in-cylinder injection valve 18d is stopped, respectively, The temperature change amounts of the main body of the in-cylinder injection valve 18d and the internal fuel that are generated from when the fuel injection operation is stopped to when it is restarted are represented by Σ (ΔDTb) and Σ (ΔDTf), respectively. Therefore, the main body correction coefficient Kdb and the fuel correction coefficient Kdf are respectively shown in FIGS. 4 (E) and 4 (F), and the temperature change amounts Σ (ΔDTt), Σ (ΔDtf) ) Increases as each increases.

  The temperature change amount ΔDTt per unit time at the tip of the in-cylinder injection valve 18d while the fuel injection operation from the in-cylinder injection valve 18d is stopped is calculated by the following equation.

ΔDTt = kthw4 + kkcomb + kf3
kthw4 represents the temperature change at the tip of the in-cylinder injection valve 18d by the engine body 1, and increases as the engine coolant temperature thw increases as shown in FIG. 6 (A). kcomb represents the temperature change at the tip of the in-cylinder injection valve 18d due to the gas in the combustion chamber 5, and decreases as the port injection amount PQ increases as shown in FIG. 6B. kf3 represents the temperature change at the tip of the in-cylinder injection valve 18d due to the fuel supplied into the common rail 19d, and increases as the fuel temperature Tf in the fuel tank 21 increases as shown in FIG. 6C. Become.

  On the other hand, the temperature change amount ΔDTb per unit time of the main body of the in-cylinder injection valve 18d while the fuel injection action from the in-cylinder injection valve 18d is stopped is calculated by the following equation.

ΔDTb = kthw5 + kspd3 + kf3
kthw5 represents the temperature change of the in-cylinder injection valve 18d body by the engine body 1, and increases as the engine coolant temperature thw increases as shown in FIG. 6 (D). kspd3 represents the temperature change of the in-cylinder injection valve 18d due to the vehicle running wind, and decreases as the vehicle speed SPD increases as shown in FIG. 6 (E). kf3 represents the temperature change at the tip of the in-cylinder injection valve 18d due to the fuel supplied into the common rail 19d, and increases as the fuel temperature Tf in the fuel tank 21 increases as shown in FIG. 6 (F). Become.

  The temperature change amount ΔDTf per unit time of the internal fuel of the in-cylinder injection valve 18d while the fuel injection operation from the in-cylinder injection valve 18d is stopped is calculated by the following equation.

ΔDTf = kthw6 + kspd4
kthw6 represents the temperature change of the fuel in the cylinder injection valve 18d by the engine body 1, and increases as the engine coolant temperature thw increases as shown in FIG. 6 (G). kspd4 represents the temperature change of the internal fuel in the in-cylinder injection valve 18d due to the vehicle running wind, and decreases as the vehicle speed SPD increases as shown in FIG. 6 (H).

  That is, when the fuel injection action from the in-cylinder injection valve 18d is stopped, ΔDTt, ΔDTb, ΔDTf are calculated and their integrated values Σ (ΔDTt), Σ (ΔDTb), Σ (ΔDTf) are calculated. The When the fuel injection action from the in-cylinder injection valve 18d is to be resumed, Kdt, Kdb, and Kdf are calculated from the integrated values Σ (ΔDTt), Σ (ΔDTb), and Σ (ΔDTf) at this time, respectively, and the correction coefficient Kd at the time of restart Is calculated.

  Incidentally, in the internal combustion engine shown in FIG. 1, the fuel injection action from the port injection valve 18p and the in-cylinder injection valve 18d is stopped during engine deceleration operation. This will be briefly described with reference to FIG. Note that the routine of FIG. 7 is executed by interruption every predetermined set time.

  Referring to FIG. 7, at step 80, it is judged if the engine load L determined according to the depression amount of the accelerator pedal 40 is zero. When L> 0, the processing cycle is terminated. Next, when L = 0, the routine proceeds to step 81, where it is determined whether or not a flag that is set when the fuel injection action from the port injection valve 18p and the in-cylinder injection valve 18d should be stopped is set. When the flag is reset, the routine proceeds to step 82, where it is determined whether or not the engine speed Ne is higher than a predetermined first set speed Ne1. When Ne ≦ Ne1, the routine proceeds to step 83 where the flag is reset, and at step 84, the fuel injection action from the port injection valve 18p or the in-cylinder injection valve 18d is executed. On the other hand, when Ne> Ne1, the routine proceeds to step 85, where the flag is set, and at step 86, the fuel injection action from the port injection valve 18p and the in-cylinder injection valve 18d is stopped. When the flag is set, the routine proceeds from step 81 to step 87, where it is determined whether or not the engine speed Ne is lower than a predetermined second set speed Ne2 (<Ne1). When Ne ≧ Ne2, the routine proceeds to steps 85 and 86 where the fuel injection operation is continued and stopped. When Ne <Ne2, the routine proceeds to steps 83 and 84 and the flag is reset, and then from the port injection valve 18p or the in-cylinder injection valve 18d. The fuel injection action is executed.

  Therefore, in the embodiment according to the present invention, when the engine load L is lower than the set load LX or during the engine deceleration operation, the fuel injection action from the port injection valve 18p is stopped, and the engine load L is higher than the set load LX or This means that the fuel injection action from the cylinder injection valve 18d is stopped during the engine deceleration operation.

  8 and 9 show the fuel injection amount calculation routine of the embodiment according to the present invention. This routine is executed by interruption every predetermined time.

  8 and 9, in step 100, it is determined whether or not the engine is operating. When not operating for a period, the processing cycle is terminated. Next, when the engine is in operation, the routine proceeds to step 101. Steps 101 to 112 are parts for calculating the port injection amount PQ. In step 101, it is determined whether or not the fuel injection action from the port injection valve 18p should be stopped. When the fuel injection action from the port injection valve 18p is to be stopped, the routine proceeds to step 102 where the port injection amount PQ is made zero. In the subsequent step 103, the temperature change amounts ΔPTt, ΔPTb, ΔPTf for the port injection valve 18p are calculated as described above, and the respective integrated values Σ (ΔPTt), Σ (ΔPTb), Σ (ΔPTf) are calculated ( Σ (ΔPTt) = Σ (ΔPTt) + ΔPTt, Σ (ΔPTb) = Σ (ΔPTb) + ΔPTb, Σ (ΔPTf) = Σ (ΔPTf) + ΔPTf). Next, the process jumps to step 113. On the other hand, when the fuel injection action from the port injection valve 18p is to be executed, the routine proceeds from step 101 to step 104, where it is determined whether or not the fuel injection action from the port injection valve 18p should be resumed. That is, when the routine proceeds to step 104 for the first time after the fuel injection action from the port injection valve 18p is stopped, the routine then proceeds to step 105, where the temperature change integrated values Σ (ΔPTt), Σ (ΔPTb), Σ (ΔPTf ), The correction coefficients Kpt, Kpb, and Kpf are calculated, and the restart correction coefficient Kp is calculated (Kp = Kpt + Kpb + Kpf). In the subsequent step 106, the temperature change integrated values Σ (ΔPTt), Σ (ΔPTb), and Σ (ΔPTf) are set to zero. Then jump to step 111.

  On the other hand, when it is determined at step 104 that the fuel injection action from the port injection valve 18p should be continued, the routine proceeds to step 107 where the attenuation amount ΔKp is calculated. In the following step 108, the restart correction coefficient Kp is calculated (Kp = Kp−ΔKp). In the following step 109, it is determined whether or not the restart correction coefficient Kp is smaller than 1.0. When Kp ≧ 1.0, the routine jumps to step 111. When Kp <1.0, the process proceeds to step 110, and after setting Kp to 1.0, the process proceeds to step 111. In step 111, the basic fuel injection amount PQB and other correction coefficients KpC are calculated. In the following step 112, the port injection amount PQ is calculated (PQ = PQB · Kp · KpC). Next, the routine proceeds to step 113.

  Steps 113 to 124 are portions for calculating the in-cylinder injection amount DQ. In step 113, it is determined whether or not the fuel injection action from the cylinder injection valve 18d should be stopped. When the fuel injection action from the in-cylinder injection valve 18d is to be stopped, the routine proceeds to step 114 where the in-cylinder injection amount DQ is made zero. In the following step 115, the temperature change amounts ΔDTt, ΔDTb, ΔDTf for the in-cylinder injection valve 18d are calculated as described above, and the respective integrated values Σ (ΔDTt), Σ (ΔDTb), Σ (ΔDTf) are calculated. (Σ (ΔDTt) = Σ (ΔDTt) + ΔDTt, Σ (ΔDTb) = Σ (ΔDTb) + ΔDTb, Σ (ΔDTf) = Σ (ΔDTf) + ΔDTf). The processing cycle is then terminated. In contrast, when the fuel injection action from the in-cylinder injection valve 18d is to be executed, the routine proceeds from step 113 to step 116, where it is determined whether or not the fuel injection action from the in-cylinder injection valve 18d should be resumed. That is, when the routine proceeds to step 116 for the first time after the fuel injection action from the in-cylinder injection valve 18d is stopped, the routine then proceeds to step 117, where the temperature change integrated values Σ (ΔDTt), Σ (ΔDTb), Σ ( Each correction coefficient Kdt, Kdb, Kdf is calculated from ΔDTf), and a restart correction coefficient Kd is calculated (Kd = Kdt + Kdb + Kdf). In the following step 118, the temperature change integrated values Σ (ΔDTt), Σ (ΔDTb), and Σ (ΔDTf) are set to zero. Then jump to step 123.

  On the other hand, when it is determined in step 116 that the fuel injection action from the in-cylinder injection valve 18d should be continued, the routine proceeds to step 119, where an attenuation amount ΔKd is calculated. In the following step 120, the restart correction coefficient Kd is calculated (Kd = Kd−ΔKd). In the following step 121, it is determined whether or not the restart correction coefficient Kd is smaller than 1.0. When Kd ≧ 1.0, the routine jumps to step 123. When Kd <1.0, the routine proceeds to step 122. After setting Kd to 1.0, the routine proceeds to step 123. In step 123, the basic fuel injection amount DQB and other correction coefficients KdC are calculated. In the following step 124, the port injection amount DQ is calculated (DQ = DQB · Kd · KdC).

  If a temperature sensor is attached to the fuel passages in the port injection valve 18p and the in-cylinder injection valve 18d, it seems that the temperature of the internal fuel can be easily detected. However, it is actually difficult and impractical to attach a temperature sensor to the fuel passage in the injection valve.

  As shown in FIG. 10, the present invention can also be applied to an internal combustion engine in which a plurality of cylinders are divided into a pair of cylinder groups 1A and 1B. In this internal combustion engine, as shown in FIG. 11, when the engine load L is lower than a predetermined set load LY, the operation of one cylinder group 1A is performed, and the operation of the other cylinder group 1B is stopped. When the engine load L becomes higher than the set load LY, both cylinder groups 1A and 1B are operated. Therefore, the fuel injection action in the cylinders of the other cylinder group 1B is stopped until the engine load L becomes smaller than the set load LY and then becomes larger than the set load LY again. With respect to the fuel injection amount of the cylinders in the other cylinder group 1B, the amount of change in the temperature of the fuel injection valve itself or the fuel in the fuel injection valve that occurs from when the fuel injection operation is stopped to when it is restarted is estimated. The fuel injection amount is corrected based on the temperature change amount estimated at the time of restart.

1 is an overall view of an internal combustion engine. It is a figure which shows an example of fuel-injection control. It is a time chart which shows a fuel-injection effect | action and a correction coefficient at the time of restart. It is a map which shows various correction coefficients. It is a map which shows various parameters. It is a map which shows various parameters. It is a flowchart for performing control at the time of deceleration. It is a flowchart for performing a fuel injection amount calculation routine. It is a flowchart for performing a fuel injection amount calculation routine. It is a figure which shows another Example of an internal combustion engine. It is a figure which shows another example of fuel-injection control.

Explanation of symbols

1 Engine Body 5 Combustion Chamber 7 Intake Port 18p Port Injection Valve 18d In-Cylinder Injection Valve

Claims (4)

  In an internal combustion engine that is provided with a fuel injection valve and that stops the fuel injection action from the fuel injection valve during engine operation, the fuel injection valve itself or the fuel injection valve that is generated after the fuel injection action is stopped and restarted A fuel supply control device that estimates a temperature change amount of the fuel and corrects the fuel injection amount based on the estimated temperature change amount when the fuel injection operation is resumed.   An intake passage fuel injection valve for injecting fuel into the engine intake passage and an in-cylinder fuel injection valve for injecting fuel directly into the cylinder, the fuel injection action from the intake passage fuel injection valve and the cylinder One or both of the fuel injection operation from the internal fuel injection valve is temporarily stopped according to the engine operating state, and the temperature change amount is determined for the fuel injection valve in which the fuel injection operation is stopped. 2. The fuel supply control for an internal combustion engine according to claim 1, wherein the fuel injection amount of the fuel injection valve is corrected based on the estimated temperature change amount when the fuel injection operation of the fuel injection valve is resumed. apparatus.   The fuel injection action in some cylinders of the plurality of cylinders is temporarily stopped according to the engine operating state, and the temperature change amount is set for the fuel injection valve of the cylinder in which the fuel injection action is stopped. 2. The fuel supply control device for an internal combustion engine according to claim 1, wherein the fuel injection amount of the cylinder is corrected based on the estimated temperature change amount when the fuel injection operation in the cylinder is resumed.   The fuel supply control device for an internal combustion engine according to claim 1, wherein the fuel injection operation is stopped during engine deceleration operation.

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