JP2014074337A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine in which multi-fuel containing gasoline and alcohol fuel having an octane number higher than the multi-fuel, and the high octane number fuel is saved as much as possible to improve combustion efficiency and emission performance desirably.SOLUTION: A control device of an internal combustion engine includes: a first injector capable of injecting multi-fuel containing gasoline; and a second injector capable of injecting alcohol fuel having an octane number higher than the multi-fuel. A flow rate (a low RON mass flow G1) of the multi-fuel to be injected from the first injector and a flow rate (a high RON mass flow G2) of the alcohol fuel to be injected from the second injector are calculated from an engine speed and a load on the basis of the preset characteristic so that a ratio of the alcohol fuel flow rate increases with the increase in the load of the internal combustion engine (S10), and fuel injection of the first and second injectors is controlled to be the calculated fuel flow rate (from S12 to S42).

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine that uses various fuels including gasoline and alcohol (ethanol) fuel having a higher octane number.

  Recently, it has been proposed to improve combustion efficiency and emission performance by using various fuels including gasoline and alcohol fuel with a higher octane number, and controlling the supply ratio according to the operating state. As an example, the technique described in Patent Document 1 below can be cited.

  In the technique described in Patent Document 1, high-octane fuel is directly injected into the combustion chamber with a direct-injector, low-octane fuel is injected into the intake port with a port injector, and the injection time of the direct-injector is the minimum injection time. When the time is shorter, the injection time is increased to the minimum injection time, while the injection amount from the port injector is reduced accordingly.

Japanese Patent No. 4719136

  In the technique described in Patent Document 1, the configuration as described above is intended to improve combustion efficiency while suppressing knocking. However, the direct injection injector always injects high-octane fuel in a minimum time or more. Therefore, the consumption of high octane fuel increases. As a result, a shortage of high-octane fuel may be caused, which may cause a disadvantage that the intended purpose of improving combustion efficiency while suppressing knocking cannot be achieved.

  Accordingly, the object of the present invention is to solve the above-mentioned problems, use various fuels including gasoline and alcohol fuel having a higher octane number, and improve combustion efficiency and emission performance by saving as much as possible the high octane number fuel. An object of the present invention is to provide a control device for an internal combustion engine which can be achieved as intended.

  In order to solve the above-mentioned object, the present invention includes a first injector capable of injecting various fuels including gasoline and a second injector capable of injecting alcohol fuel having an octane number higher than that of the various fuels. In the control device for an internal combustion engine that generates an output by igniting and burning an air-fuel mixture obtained by mixing fuel injected from at least one of the first and second injectors with intake air in a combustion chamber, Detection means for detecting the engine speed and load, flow rates of various fuels to be injected from the first injector based on a preset load / injection ratio characteristic from the detected engine speed and load, and the first The flow rate of the alcohol fuel to be injected from the two injectors is increased with respect to the flow rate of the various fuels as the load of the internal combustion engine increases. A flow rate calculating means for calculating the flow rate ratio; and a fuel injection control means for controlling the fuel injection of the first and second injectors so as to obtain the calculated fuel flow rate. The calculation means is configured to calculate the flow rates of the multi-fuel and the alcohol fuel so that the ratio of the flow of the multi-fuel to the flow of the alcohol fuel does not become zero even when the load of the internal combustion engine increases.

  In the control device for an internal combustion engine according to claim 2, the first injector includes an injector that directly injects the various types of fuel into the combustion chamber, and the second injector is connected to the intake port in front of the combustion chamber. It was comprised so that it might consist of an injector which injects alcohol fuel.

  In the control apparatus for an internal combustion engine according to claim 3, the flow rate calculation means calculates an adhesion correction flow rate of alcohol fuel to be injected from the second injector to the intake port wall surface, and the calculated adhesion correction The flow rate of the alcohol fuel is corrected by the flow rate.

  5. The control apparatus for an internal combustion engine according to claim 4, wherein the flow rate calculation means sets a flow rate / energization time characteristic set in advance from the calculated flow rate of the alcohol fuel when the second injector is driven from a stop. The energization time to the second injector is calculated based on the above, and when the calculated energization time is shorter than the minimum injection time that guarantees linear characteristics, the calculated energization time is increased to the minimum injection time. Configured.

  In the control apparatus for an internal combustion engine according to claim 5, the flow rate calculation means determines the flow rates of the various fuels to be injected from the first injector when the calculated energization time is increased to the minimum injection time. It was configured to correct for decrease.

  In the control apparatus for an internal combustion engine according to claim 1, the first injector capable of injecting various fuels including gasoline based on a preset load / injection ratio characteristic from the detected engine speed and load. The flow rate of the multi-fuel to be injected and the flow rate of the alcohol fuel to be injected from the second injector capable of injecting the alcohol fuel having an octane number higher than that of the multi-fuel include the ratio of the flow rate of the alcohol fuel to the flow of the multi-fuel as the load increases. The fuel injection of the first and second injectors is controlled so that the calculated fuel flow rate is obtained, and the ratio of the various fuel flow rates to the alcohol fuel flow rate is zero even when the load increases. The flow rate of various types of fuel and alcohol fuel is calculated so that the With knock by causing pressurized can be effectively suppressed, thereby improving the combustion efficiency and emission performance since it is possible to operate the internal combustion engine with a high compression ratio.

  Furthermore, since the flow rate of both types of fuel is calculated so that the ratio of the flow rate of the various fuels to the flow rate of the alcohol fuel does not become zero even when the load increases, the multiple fuels are always injected, and as a result, the alcohol fuels Consumption can be saved as much as possible, so that improvement in combustion efficiency and emission performance can be achieved as expected.

  In the control apparatus for an internal combustion engine according to claim 2, the first injector includes an injector that directly injects various fuels into the combustion chamber, and the second injector injects alcohol fuel into the intake port in front of the combustion chamber. In addition to the effects described above, since the first injector is the injector that directly injects various fuels into the combustion chamber, the various fuels are always injected from the first injector. It is possible to prevent deposits from being generated at the tip due to the influence of the combustion temperature, and it is possible to avoid abnormal combustion due to the latent heat of the injected various fuels. In addition, by using the injector that injects alcohol fuel into the intake port as the second injector, the accuracy and cost of components such as a pressure pump can be reduced, and the configuration can be simplified.

  In the control apparatus for an internal combustion engine according to claim 3, the adhesion correction flow rate of alcohol fuel to be injected from the second injector to the intake port wall surface is calculated, and the alcohol fuel flow rate is corrected by the calculated adhesion correction flow rate. Since it is configured as described above, in addition to the above-described effects, the flow rate of the alcohol fuel injected from the intake port can be calculated with high accuracy.

  In the control device for an internal combustion engine according to claim 4, when the second injector is driven from the stop, the flow rate of the alcohol fuel calculated from the calculated flow rate of the alcohol fuel is supplied to the second injector based on a preset flow rate / energization time characteristic. In addition to the above effects, the energization time is calculated, and when the calculated energization time is shorter than the minimum injection time that guarantees the linear characteristic, the calculated energization time is increased to the minimum injection time. Even when the energization time is shorter than the minimum injection time that guarantees the linear characteristics, alcohol fuel having a flow rate higher than the required flow rate can be supplied, and knocking can be effectively suppressed.

  In the control apparatus for an internal combustion engine according to claim 5, when the calculated energization time is increased to the minimum injection time, the flow rate of the various fuels to be injected from the first injector is corrected to decrease. In addition to the effect, the air-fuel ratio can be prevented from deviating from the target value.

1 is a schematic diagram showing an overall control apparatus for an internal combustion engine according to an embodiment of the present invention. It is a block diagram which shows the operation | movement of ECU shown in FIG. 1 functionally. Fig. 3 is a flowchart showing more specifically the operation of the ECU shown in Fig. 2. 3 is an explanatory diagram of the characteristics used in the processing of the flow chart. It is explanatory drawing which shows the whole characteristic of the fuel flow volume with respect to the energization time of the port injector shown in FIG. It is explanatory drawing which shows the characteristic of FIG. 5 in detail. 3 is a time chart for explaining the processing of the flow chart.

  The best mode for carrying out the control apparatus for an internal combustion engine according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing an overall control apparatus for an internal combustion engine according to an embodiment of the present invention.

  In FIG. 1, reference numeral 10 denotes a four-cylinder (cylinder) four-cycle internal combustion engine (only one cylinder is shown; hereinafter referred to as “engine”) mounted on a vehicle (not shown). In the engine 10, a compressor 14 a of the turbocharger 14 is disposed in the intake pipe 12.

  The intake air is forcibly compressed and sucked from an air cleaner (not shown) by the compressor 14a and flows through the intake pipe 12, is cooled by the intercooler 14b and reaches the throttle valve 16, where the flow rate is adjusted and the intake manifold 18 flows. When two intake valves (only one is shown) 20 are opened (opened), they flow into the combustion chamber 22.

  The throttle valve 16 is mechanically disconnected from the accelerator pedal 24 disposed on the vehicle driver's seat floor, and the opening and closing of the throttle valve 16 is controlled by a DBW (Drive By Wire) mechanism 26. That is, the throttle valve 16 is connected to an actuator (electric motor) 26a of the DBW mechanism 26, and is opened and closed by being driven by the actuator 26a.

  A first injector (INJ, fuel injection valve) 30 is disposed at a position facing the combustion chamber 22, and a second injector (INJ, fuel injection valve) 32 is disposed in the intake port 18 a before the intake valve 20. The

  Various fuels stored in the main fuel tank 34 are pumped to the first injector 30 by a main fuel pump 34 a disposed inside the tank, and are pumped through the fuel supply pipe 36. The first injector 30 directly injects the various fuels fed under pressure into the combustion chamber 22. Hereinafter, the first injector 30 is also referred to as a “direct injection injector”.

  As the multi-fuel, it is planned to use a fuel having a relatively low alcohol concentration, such as a mixed fuel of gasoline and ethanol (ethyl alcohol), specifically, a mixed fuel (E10) of 90% gasoline and 10% ethanol.

  On the other hand, the various fuels stored in the main fuel tank 34 are pumped up by the sub fuel pump 34b and sent to the separation device 42 via the conduit 40, where they are separated and extracted into alcohol components and other components. The separated alcohol component is stored in the sub fuel tank 44 as alcohol fuel having a certain range of alcohol concentration, and the other components are returned to the main fuel tank 34 via the pipe 46.

  The alcohol fuel stored in the sub fuel tank 44 is pumped up by a fuel pump 44 a disposed inside the tank, and is pumped to the second injector 32 through the fuel supply pipe 50. In other words, relatively low (low RON) fuel is pumped to the first injector 30 at the octane number (Research Octane Number), while relatively high (high RON) fuel is pumped to the second injector 32. Hereinafter, the fuel pumped to the first injector 30 is referred to as a low RON fuel, and the fuel pumped to the second injector 32 is referred to as a high RON fuel.

  The second injector 32 injects the pumped high RON fuel into the intake port 18a. Hereinafter, the second injector 32 is also referred to as a “port injector”. The injected high RON fuel flows into the combustion chamber 22 when the intake valve 20 is opened.

  The direct injection injector 30 or the port injector 32 is electrically connected to an ECU (Electronic Control Unit) 54 through a driver (drive circuit; shown in FIG. 2) 52 and indicates a valve opening (opening) time from the ECU 54. When the drive signal is supplied through the driver 52, the valve is opened, low RON fuel corresponding to the valve opening time is injected into the combustion chamber 22, and high RON fuel is injected into the intake port 18a. The injected low RON fuel or high RON fuel is mixed with the inflowing air to generate an air-fuel mixture.

  A spark plug 56 is disposed in the combustion chamber 22. The spark plug 56 is connected to an ignition device 60 such as an igniter. When an ignition signal is supplied from the ECU 54 via the driver 52, the ignition device 60 generates a spark discharge between the electrodes of the spark plug 56. The air-fuel mixture is ignited and combusted thereby, and drives the piston 62 slidably accommodated in the combustion chamber 22 downward.

  Inside the cylinder block 64 in which the combustion chamber 22 is formed, a crankshaft (not shown) that is connected to the piston 62 and converts the vertical motion of the piston 62 into rotational motion is accommodated.

  Exhaust gas (exhaust gas) generated by the combustion flows from the exhaust manifold 74 to the exhaust pipe 76 through the exhaust port 72 when two exhaust valves (only one is shown) 70 are opened. A turbine 14c of the turbocharger 14 is disposed in the exhaust pipe 76, and is rotated (driven) by exhaust gas. The turbine 14c is mechanically connected to the compressor 14a, and the compressor 14a is rotated (driven) accordingly to forcibly suck and suck the intake air.

  The exhaust pipe 76 is provided with a bypass passage 76a that bypasses the turbine 14c. A waste gate valve 14d is disposed in the bypass passage 76a. An actuator 14d1 composed of an electromagnetic solenoid valve is attached to the wastegate valve 14d.

  When the actuator 14d1 is energized, it drives the wastegate valve 14d to the open position and opens the bypass passage 76a. The rotational speed of the turbine 14c is controlled by adjusting the opening degree of the waste gate valve 14d via the actuator 14d1, and thus the supercharging pressure of the turbocharger 14 is controlled.

  A catalyst device (not shown) is disposed in the exhaust pipe 76 downstream of the bypass passage 76a. Exhaust gas is discharged to the atmosphere outside the engine after removing harmful components such as HC, CO, NOx by the catalyst device.

  The cylinder head 64 a is provided with a valve opening / closing timing variable mechanism (hereinafter referred to as “VTC”) 80. The VTC 80 is a hydraulic motor that can change the timing for opening and closing the combustion chamber of the intake valve, which is defined as a phase angle (VTC angle) of the camshaft with respect to the crankshaft by driving the camshaft via hydraulic pressure. In addition to the VTC 80, a mechanism capable of changing the opening / closing phase angle and the lift amount of the intake cam 80b according to a plurality of cams may be provided.

  A crank angle sensor 82 is disposed in the vicinity of the crankshaft of the engine 10. The crank angle sensor 82 includes a magnetic pickup that outputs a signal corresponding to the rotation of the pulsar 82a fixed to the crankshaft. The crank angle sensor 82 is a cylinder discrimination signal and TDC (top dead center) of each cylinder or a TDC indicating a crank angle in the vicinity thereof. A CRK signal obtained by subdividing the signal and the TDC signal is output.

  An air flow meter 84 having a temperature detecting element is disposed in the intake pipe 12 and outputs a signal corresponding to an intake (air) amount Q taken from the air cleaner and an intake air temperature TA.

  In the intake pipe 12, a throttle pre-pressure sensor 85 is disposed upstream of the throttle valve 16, outputs a signal indicating the intake pipe pressure PBA upstream of the throttle valve 16 in absolute pressure, and a MAP sensor 86 is disposed downstream. Then, a signal indicating the intake pipe pressure PBA at the downstream position of the throttle valve 16 in absolute pressure is output.

  A cam sensor 88 is disposed on the camshaft to output a signal indicating the phase angle of the camshaft with respect to the crankshaft, and a throttle opening sensor 90 is disposed on the DBW mechanism 26 to position the throttle valve 16 (throttle opening). A signal corresponding to the degree TH) is output.

  A water temperature sensor 92 is disposed in a cooling water passage (not shown) formed in the cylinder block 64 of the engine 10 and outputs a signal corresponding to the engine cooling water temperature (engine temperature) TW. 94 is arranged to output a signal corresponding to vibration generated in the engine 10 due to knocking.

  In the exhaust system, an A / F sensor (wide area air-fuel ratio sensor) 96 is arranged upstream of the catalyst device, and in a wide range from the stoichiometric air-fuel ratio to rich or lean, in other words, the actual air concentration. A signal indicating the fuel ratio KACT is output.

  A pipe 40 connecting the main fuel tank 34 and the separation device 42 is provided with an alcohol sensor 100 and low RON fuel flowing through the pipe 40, more specifically, alcohol of low RON fuel stored in the main fuel tank 34. In addition to outputting a signal indicating the concentration, a level sensor 102 is disposed in the sub fuel tank 44, and the level (liquid level height) of the high RON fuel stored in the sub fuel tank 44, in other words, the remaining high RON fuel. A signal indicating the quantity is output. Note that an alcohol sensor may also be disposed in a pipe line connecting the sub fuel tank 44 and the separation device 42 to detect the alcohol concentration of the high RON fuel.

  An accelerator opening sensor 104 is provided in the vicinity of the accelerator pedal 24, and outputs a signal corresponding to the accelerator opening AP indicating the amount by which the driver depresses the accelerator pedal. A vehicle speed sensor 106 is provided in the vicinity of a drive shaft (not shown), and outputs a pulse signal per predetermined angular rotation of the drive shaft.

  The output of the sensor group described above is input to the ECU 54. The ECU 54 includes a microcomputer and includes a CPU, a ROM, a RAM, an I / F, and the like. The ECU 54 measures (detects) the engine speed NE and the vehicle speed V by measuring the time interval between the output of the crank angle sensor 82 (CRK signal) and the output of the vehicle speed sensor 106 among the input signals.

  FIG. 2 is a block diagram functionally showing the operation of the ECU 54. The ECU 54 executes the illustrated process based on the input sensor output.

  As will be described below, the ECU 54 includes a fuel injection / ignition control unit 54a, in which the engine speed detected by the crank angle sensor 82 and the cylinder sucked into the cylinder (cylinder) of the engine 10 detected by the air flow meter 84. A basic value of the fuel injection amount is calculated according to appropriate characteristics from basic parameters such as the internal intake air amount (indicating the load of the engine 10).

  The calculated basic value is an air-fuel ratio feedback correction coefficient calculated based on A / F (air-fuel ratio) detected from the A / F sensor 96, or a correction coefficient calculated according to knocking detected from the knocking sensor 94. Are added (or multiplied), and a correction coefficient calculated based on the other parameters shown in the figure is added (or multiplied) as necessary.

More specifically, the fuel injection amount corresponds to the in-cylinder intake amount sucked into the cylinder of the engine 10 and the necessary heat generation so that the air-fuel ratio detected from the A / F sensor becomes the target value. The amount [MJ / m ³ ] is calculated, and then, as will be described later, the injection ratio, the number of injections, and the injection timing are calculated as mass flow rates of the low RON fuel and the high RON fuel.

  Further, the ignition timing is calculated according to appropriate characteristics, and is corrected by a correction coefficient calculated according to knocking detected from the knocking sensor 94. A control value is calculated based on the calculated fuel injection amount and ignition timing, and is supplied to the direct injection injector 30, the port injector 32, and the spark plug 56 via the driver 52.

  Further, in the intake air amount control unit 54b, a required output required by the driver is calculated by searching for appropriate characteristics from the accelerator opening AP, the vehicle speed, and the engine speed, and the calculated required output is satisfied. Thus, the target intake air amount is calculated.

  Next, a target throttle (TH) opening, a target boost pressure, and a target VTC angle are calculated based on the calculated target intake air amount, and the calculated value, actual opening, actual boost pressure, A feedback correction coefficient is added (or multiplied) so that the deviation from the actual angle decreases, and a control value is calculated and supplied to the DBW mechanism 26, the wastegate valve actuator 14d1 and the VTC 80 via the driver 52.

  FIG. 3 is a flow chart showing the operation of the ECU 54 more specifically, and FIGS. 4A, 4B, and 4C are explanatory diagrams of characteristics used in the processing of FIG. The illustrated program is executed for each combustion cycle (consisting of four strokes) calculated from an appropriate crank angle near the TDC of each cylinder.

  In the following, the high RON required injection ratio Eratio (%) is calculated in S10. This is performed by searching the characteristic (load / injection ratio characteristic) 100 shown in FIG. 4A from the engine speed NE and the in-cylinder intake air amount (load) detected from the crank angle sensor 82 and the air flow meter 84. .

  As shown in the figure, the high RON required injection ratio Eratio is the ratio of the high RON fuel to the low RON fuel (more precisely, the mass flow rate of the high RON fuel relative to the total injected fuel (the mass flow rate of the low RON fuel and the high RON fuel)). The ratio is set to increase as the value of the in-cylinder intake amount with respect to the engine speed NE increases.

  The characteristic 100 is composed of a plurality of threshold values from a minimum threshold value 100a to a maximum threshold value 100b as shown in the figure. The high RON required injection ratio Eratio is, for example, 0% (low RON mass flow rate 100%, high RON mass flow rate 0%) when the in-cylinder intake amount is less than the minimum threshold value 100a, and the maximum threshold value 100b. It is set to be 70% (low RON mass flow rate 30%, high RON mass flow rate 70%). A value between the minimum threshold value 100a and the maximum threshold value 100b is calculated by interpolation.

  Thus, in the high RON required injection ratio Eratio, when the in-cylinder intake amount is less than the minimum threshold value 100a, the high RON mass flow rate is set to 0%, while the in-cylinder intake amount is set to the maximum threshold value. The low RON mass flow rate is set to 30%, in other words, not to be zero, that is, to save high RON fuel even when increasing to exceed 100b.

  Returning to the description of the flow chart of FIG. 3, the process then proceeds to S12 to calculate the required calorific value Calo_total. The necessary calorific value Calo_total corresponds to the in-cylinder intake air sucked into the cylinder of the engine 10 as described above, and is calculated so that the air-fuel ratio detected from the A / F sensor becomes the target value. The target value of the air-fuel ratio is set at or near the theoretical air-fuel ratio.

  Next, the process proceeds to S14, and, as shown in the equation in the figure, a high RON (fuel) mass flow rate (required injection amount) G2 is obtained from the high RON required injection ratio Eratio calculated in S10 and the required heat generation value Calo_total calculated in S12. Calculate (FIG. 4B).

  In the equation, Calo2 means a high RON (fuel) low calorific value, that is, a value obtained by subtracting the product of the condensation latent heat of water vapor and the water vapor amount from the high calorific value. As the high RON low calorific value Calo2, a value obtained in advance through experiments is used.

  As is clear from the equation shown in the drawing, when the in-cylinder intake amount is small and the high RON required injection ratio Eratio calculated in S10 is 0, the high RON mass flow rate G2 is zero.

  Next, the processing proceeds to S16, and the high RON (fuel) port injector (port INJ) is searched from the calculated high RON mass flow rate G2 according to the characteristic (flow rate / injection time characteristic) 102 shown in FIG. ) 32 valve opening time T2 is calculated.

  Next, in S18, it is determined whether or not the port injector 32 is being driven. That is, it is determined whether the port injector 32 is driven in addition to the direct injection injector 30, in other words, whether the engine load (in-cylinder intake air amount) is relatively large.

  When the result in S18 is negative, the program proceeds to S20, where it is determined whether or not the calculated valve opening time T2 of the port injector 32 exceeds the threshold value T2_ON, and when the result is affirmative, the program proceeds to S22 and the calculated valve opening time. The port injector 32 is driven at T2.

  3 will be described with reference to FIG. 5 and subsequent figures before continuing the description of FIG. 3. FIG. 5 (a) shows the overall characteristics of the fuel flow rate with respect to the energization time of the port injector 32. FIG. FIG. 6B is an enlarged view of the characteristic portion A of FIG. 6A, and FIG. 6 is an explanatory diagram showing the characteristics of FIG. 5B in more detail.

  In the port injector 32 (and the direct injection injector 30), the fuel flow rate shows a substantially linear characteristic with respect to the energization time because the needle valve moves backward to the perforated open position in response to energization (excitation). . However, while the energization amount is a minute value, the needle valve does not retract (invalid time), and when the energization amount exceeds the minute value (minimum injection time), the needle valve retracts all at once to the perforation opening position.

  Since this minimum injection time (shown as “T2lmt” in FIG. 6) guarantees linear characteristics, in the process of the flowchart of FIG. 3, when the calculated energization time T2 is less than the minimum injection time, the minimum injection time The time was extended.

  Further, since the port injector 32 is intermittently driven, threshold values T2_ON and T2_OFF are provided as shown in FIG. 6 to prevent control hunting when switching from stop to drive and from drive to stop. Comparison was made with time T2.

  Specifically, in order to drive the port injector 32 from the stop, the valve opening time T2 exceeds the threshold value T2_ON, and in order to stop from the driving, the valve opening time T2 is less than the threshold value T2_OFF. Control hunting was prevented from occurring by assuming that

  Returning to the description of the flow chart of FIG. 3 on the premise of the above, when the drive condition described above is determined in S20, if affirmative (satisfied), the process proceeds to S22, and the port injector 32 is driven.

  Next, the process proceeds to S24, in which it is determined whether or not the calculated valve opening time T2 of the port injector 32 is less than the minimum injection time T2lmt. If the result is negative, the process proceeds to S26, and the calculated valve opening time T2 of the port injector 32 is used as it is. The output (final) valve opening time is T2out.

  On the other hand, when the result in S24 is affirmative, the program proceeds to S28, and the minimum injection time T2lmt is set as the output (final) valve opening time T2out. In other words, the calculated valve opening time T2 is increased to the minimum injection time T2lmt.

  Further, since the valve opening time T2 is increased to the minimum injection time T2lmt, the calculated high RON mass flow rate G2 is also increased to the mass flow rate G2lmt corresponding to the minimum injection time T2lmt.

  On the other hand, when the result in S18 is affirmative and it is determined that the port injector 32 is being driven, the routine proceeds to S30, where it is determined whether or not the calculated valve opening time T2 of the port injector 32 is equal to or greater than the stop-side threshold value T2_OFF.

  If the determination in S30 is affirmative, the process proceeds to S22 because the stop condition is not satisfied. If the determination is negative, the process proceeds to S32 because the stop condition is satisfied, and the port injector 32 is stopped.

  Next, in S34, the output (final) valve opening time T2out and the high RON mass flow rate G2 are set to zero.

  Next, in S36, the adhesion correction flow rate Gst is calculated. That is, since the port injector 32 injects fuel into the intake port 18a, the fuel adhering to the wall surface of the intake port 18a is estimated and corrected for the amount of fuel drawn into the combustion chamber 22 after a transition. .

  The adhesion correction flow rate Gst is a direct rate (a proportion of fuel injected into the combustion chamber 22 during the combustion cycle of the fuel injected in a certain combustion cycle) and a take-off rate (a wall surface injected before a certain combustion cycle). Of the fuel adhering to the combustion chamber (the ratio of the fuel sucked into the combustion chamber 22 during the combustion cycle) and the like. No. 5 -187293), detailed description thereof is omitted.

  Next, in S38, a low RON (fuel) mass flow rate G1 to be injected from the direct injection injector 30 is calculated according to the equation shown in the figure. In the equation, Calo1 indicates a low RON (of fuel) low calorific value.

  As apparent from FIG. 4 (a), the fuel is calculated as the sum of the low RON fuel and the high RON fuel. Therefore, in the equation shown, the low RON mass flow rate G1 is high from the fuel corresponding to the required calorific value Calo_total. It is calculated by subtracting the RON mass fuel G2 and the adhesion correction flow rate Gst.

  Further, when the valve opening time T2 calculated in S28 is increased to the minimum injection time T2lmt, the difference (G2-G2lmt) is also subtracted from the low RON mass flow rate G1 in S38.

  Next, the process proceeds to S40, and the valve opening time T1 of the low RON (fuel) direct injection injector 30 according to an appropriate characteristic not shown (characteristic similar to the characteristic shown in FIG. 5A) from the calculated low RON mass flow rate G1. Is calculated.

  Next, in S42, the calculated valve opening time T1 is set as an output (final) valve opening time T1out.

  FIG. 7 is a time chart for explaining the processing of the flowchart of FIG.

  As shown in the figure, the high RON required injection ratio is increased according to the required load (in-cylinder intake amount or required calorific value Calo_total) of the engine 10, and the high RON fuel is increased accordingly (relative to the low RON fuel). . Thus, knocking can be effectively suppressed, and the engine 10 can be operated at a high compression ratio, so that combustion efficiency and emission performance can be improved.

  Furthermore, since the ratio of the low RON fuel to the high RON fuel is calculated so that it does not become zero even when the required load increases, the low RON fuel is always injected, and as a result, the high RON fuel can be consumed. As much as possible can be saved, so that the improvement in combustion efficiency and emission performance can be achieved as expected.

  Further, since the adhesion correction flow rate Gst to the intake port wall surface of the high RON fuel is calculated and the flow rate of the low RON fuel is corrected by the calculated adhesion correction flow rate Gst, the flow rate of the low RON fuel can be accurately calculated. .

  Further, when the energization time T2 to the port injector 32 is shorter than the minimum injection time T2lmt that guarantees the linear characteristics, the flow increases to the minimum injection time and the flow rate of the low RON fuel is corrected to decrease by the increased difference (G2-G2lmt). As a result, the air-fuel ratio can be prevented from deviating from the target value.

  In the above description, the flow rate of the fuel is indicated by the mass flow rate. However, since the volume flow rate is obtained by dividing the mass flow rate by the air density, the volume flow rate is also equivalent.

  As described above, in this embodiment, the first injector 30 capable of injecting various fuels including gasoline (low RON fuel) and the alcohol fuel (high RON fuel) having a higher octane number than the various fuels can be injected. An internal combustion engine (which includes a second injector 32) and produces an output by igniting and burning an air-fuel mixture obtained by mixing fuel injected from at least one of the first and second injectors with intake air in the combustion chamber 22 ( In the control device of the engine 10, detection means (82, 84, 54) for detecting the engine speed (engine speed) NE and load (cylinder intake air amount) of the internal combustion engine, and the detected engine speed The flow rate of various fuels (low RON mass flow rate G1) to be injected from the first injector based on the preset load / injection ratio characteristic 100 from the 2 As the flow rate of alcohol fuel to be injected from the injector (high RON mass flow rate G2) increases, the ratio of the flow rate of the alcohol fuel to the flow rate of the various fuels increases as the load of the internal combustion engine (in-cylinder intake air amount) increases. The flow rate calculation means (ECU 54, S10) calculated as described above, and the fuel injection control means (ECU 54, S12 to S42) for controlling the fuel injection of the first and second injectors so that the calculated fuel flow rate is obtained. And the flow rate calculating means calculates the flow rates of the multifuel and the alcohol fuel so that the ratio of the flow rate of the multifuel to the flow rate of the alcohol fuel does not become zero even when the load of the internal combustion engine increases. (ECU 54, S12 to S42) Since it is configured, alcohol fuel (high RON fuel) as load increases Increasing is possible effectively suppress knocking in, it is possible to improve the combustion efficiency and emission performance since it is possible to operate the engine 10 at a high compression ratio.

  Further, since the ratio of the flow rate of the various fuels (low RON mass flow rate) to the flow rate of the alcohol fuel (high RON mass flow rate) does not become zero even when the load increases, the flow rate of both is calculated. The fuel (low RON fuel) is always injected, and as a result, the consumption of alcohol fuel (high RON fuel) can be saved as much as possible, so that the improvement of combustion efficiency and emission performance can be achieved as expected. it can.

  The first injector includes an injector 30 that directly injects the multi-fuel (low RON fuel) into the combustion chamber 22 (direct injection), and the second injector is connected to the alcohol intake port before the combustion chamber. In addition to the above-described effects, the injector for directly injecting various types of fuel (low RON fuel) into the combustion chamber 22 is used as the first injector 30. Since multiple fuels are always injected from one injector, it is possible to prevent deposits from being generated at the tip due to the influence of the in-cylinder combustion temperature, and to avoid abnormal combustion due to the latent heat of the injected multiple fuels. it can.

  Further, by using the second injector 32 as an injector that injects alcohol fuel (high RON fuel) into the intake port, the accuracy and cost of components such as a pressure pump can be reduced, and the configuration can be simplified.

  The flow rate calculation means calculates an adhesion correction flow rate Gst to the wall surface of the intake port 18a of alcohol fuel (high RON fuel) to be injected from the second injector 32, and the alcohol fuel is calculated using the calculated adhesion correction flow rate. In addition to the above-described effects, the flow rate of alcohol fuel injected from the intake port 18a can be calculated with high accuracy.

  Further, when the second injector 32 is driven from the stop, the flow rate calculation means is configured to apply the energization time to the second injector based on the flow rate / energization time characteristic 102 set in advance from the calculated flow rate of the alcohol fuel. T2 is calculated (ECU 54, S16), and when the calculated energization time T2 is shorter than the minimum injection time T2lmt that guarantees linear characteristics, the calculated energization time is increased to the minimum injection time (ECU 54, S24). , S28), in addition to the above-described effects, at least the calculated flow rate of alcohol fuel (high RON fuel) is supplied even when the calculated energization time T2 is shorter than the minimum injection time T2lmt that guarantees linear characteristics. be able to.

  The flow rate calculation means decreases and corrects the flow rate of the various fuels to be injected from the first injector (in G2-G2lmt) when the calculated energization time is increased to the minimum injection time (ECU54, S38). In addition to the effects described above, it is possible to prevent the air-fuel ratio from deviating from the target value.

  In the above description, the main fuel tank 34 stores various fuels including alcohol fuel, and the sub fuel tank 44 stores alcohol fuel. However, the main fuel tank 34 stores gasoline fuel and the sub fuel tank 44 stores alcohol fuel. You may do it.

  DESCRIPTION OF SYMBOLS 10 Internal combustion engine (engine), 14 Turbocharger, 14a Compressor, 14c Turbine, 14d Wastegate valve, 14d1 Wastegate valve actuator, 16 Throttle valve, 18 Intake manifold, 18a Intake port, 20 Intake valve, 22 Combustion chamber , 26 DBW mechanism, 30 first (direct injection) injector, 32 second (port) injector, 34 main fuel tank, 42 separator, 44 sub fuel tank, 54 ECU (electronic control unit), 56 spark plug (ignition means) ), 60 ignition device (ignition means), 80 VTC (variable valve opening timing mechanism), 82 crank angle sensor, 84 air flow meter, 86 MAP sensor, 90 throttle opening sensor, 96 A / F sensor, 100 alcohol sensor, 02 level sensor, 104 an accelerator opening sensor

Claims (5)

  A fuel injected from at least one of the first and second injectors, comprising: a first injector capable of injecting various fuels including gasoline; and a second injector capable of injecting alcohol fuel having an octane number higher than that of the various fuels. In a control apparatus for an internal combustion engine that generates an output by igniting and burning an air-fuel mixture obtained by mixing the air and intake air in a combustion chamber, detection means for detecting the engine speed and load of the internal combustion engine, and the detected engine Based on a load / injection ratio characteristic set in advance from the rotational speed and the load, the flow rate of various fuels to be injected from the first injector and the flow rate of alcohol fuel to be injected from the second injector are determined as the load of the internal combustion engine. The flow rate calculation means for calculating so that the ratio of the flow rate of the alcohol fuel to the flow rate of the various fuels increases as the flow rate increases. Fuel injection control means for controlling the fuel injection of the first and second injectors so that the calculated fuel flow rate is obtained, and the flow rate calculation means also when the load of the internal combustion engine increases. A control device for an internal combustion engine, wherein the flow rates of the multi-fuel and the alcohol fuel are calculated so that the ratio of the flow of the multi-fuel to the flow of the alcohol fuel does not become zero.   The first injector is an injector that directly injects the various fuels into the combustion chamber, and the second injector is an injector that injects the alcohol fuel into an intake port in front of the combustion chamber. The control apparatus for an internal combustion engine according to claim 1.   The flow rate calculating means calculates an adhesion correction flow rate of alcohol fuel to be injected from the second injector to the intake port wall surface, and corrects the alcohol fuel flow rate with the calculated adhesion correction flow rate. The control device for an internal combustion engine according to claim 2.   The flow rate calculation means calculates the energization time to the second injector based on a preset flow rate / energization time characteristic from the calculated flow rate of the alcohol fuel when driving the second injector from a stop. 4. The calculated energization time is increased to the minimum injection time when the calculated energization time is shorter than a minimum injection time that guarantees linear characteristics. Control device for internal combustion engine.   5. The internal combustion engine according to claim 4, wherein the flow rate calculation means corrects the flow rate of the various fuels to be injected from the first injector when the calculated energization time is increased to the minimum injection time. Control device.

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