JP2007285193A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply composite fuel of a stable property in starting or the like by suitably eliminating phase separation occurring in a fuel tank. <P>SOLUTION: The control device of the internal combustion engine controls the internal combustion engine having a first fuel tank for storing the composite fuel of gasoline and alcohol and a second fuel tank (having an alcohol concentration higher than the first fuel tank). The control device of the internal combustion engine forcibly discharges fuel in a water-alcohol phase to the outside of the first fuel tank when the phase separation occurs in the first fuel tank. The phase separation occurring in the first fuel tank can be thus eliminated. An interface of the phase separation can be lowered below a fuel inlet opening. According to the above control device of the internal combustion engine, suitable starting by using the fuel of the first fuel tank is performed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that controls an internal combustion engine that uses a mixed fuel of gasoline and alcohol.

  Conventionally, an internal combustion engine using a mixed fuel of gasoline and alcohol is known. Such a mixed fuel is known to easily separate gasoline and alcohol when the alcohol concentration is low or when the mixed fuel contains a certain amount or more of water. When gasoline and alcohol are separated (hereinafter referred to as “phase separation”), the mixed fuel having a stable property cannot be supplied, and thus combustion of the internal combustion engine may become unstable.

  Japanese Patent Application Laid-Open No. 2004-151858 discloses a technique for starting an engine after performing fuel mixing (stirring) to equalize the fuel when phase separation occurs at the time of starting in an internal combustion engine using such a mixed fuel. Is described. In addition, Patent Documents 2 and 3 exist as prior art documents related to the present invention.

JP-A-6-26414 Japanese Patent Laid-Open No. 7-19124 JP-A-5-209565

  However, with the technique described in Patent Document 1 described above, phase separation is resolved immediately after stirring is performed, but it is highly possible that phase separation will recur after a certain amount of time has passed. This is because the proportion of moisture contained in the fuel does not change even when stirring. For this reason, there is a case where a mixed fuel having a stable property cannot be supplied. Further, even with the techniques described in Patent Documents 2 and 3, it has been difficult to appropriately eliminate the phase separation and supply a stable mixed fuel.

  The present invention has been made to solve the above-described problems, and can appropriately eliminate the phase separation generated in the fuel tank and supply a stable mixed fuel at the time of start-up. An object of the present invention is to provide a control device for an internal combustion engine.

  In one aspect of the present invention, there is provided a first fuel tank that stores a mixed fuel of gasoline and alcohol, and a mixed fuel that is a mixed fuel of gasoline and alcohol and has a higher alcohol concentration than the first fuel tank. A control device for an internal combustion engine that controls an internal combustion engine having a second fuel tank that stores the fuel in the first fuel tank, wherein the mixed fuel includes the gasoline phase, the alcohol, and water. Phase separation determining means for determining whether or not the phases are separated from each other, and when the phase separation determining means determines that the phase separation has occurred, the phase-separated alcohol and And a discharge control means for performing control for forcibly discharging the fuel in the phase composed of water to the outside of the first fuel tank.

  The above control device for an internal combustion engine controls an internal combustion engine having a first fuel tank and a second fuel tank that store a mixed fuel of gasoline and alcohol. In this case, the mixed fuel in the second fuel tank is set to have a higher alcohol concentration than the mixed fuel in the first fuel tank. The phase separation determination means determines whether or not the gasoline phase and the phase composed of alcohol and water are separated in the first fuel tank. The discharge control means forcibly discharges the fuel in the phase constituted by the phase-separated alcohol and water to the outside of the first fuel tank. Specifically, the phase separation determination means discharges the phase-separated fuel at an injection amount or an injection timing different from the fuel injected according to the required load of the vehicle. Thereby, it becomes possible to eliminate the phase separation generated in the first fuel tank by reducing the ratio of moisture in the fuel in the first fuel tank. Further, since the position of the phase separation boundary surface can be lowered from the position of the fuel suction, when the fuel in the first fuel tank is used at the time of starting, the fuel having a high gasoline concentration (that is, the fuel in the gasoline phase) ) Can be supplied to the internal combustion engine. Therefore, according to the control apparatus for an internal combustion engine, it is possible to perform an appropriate start using the fuel in the first fuel tank.

  In one aspect of the control apparatus for an internal combustion engine, the discharge control means can discharge the fuel into an exhaust passage of the internal combustion engine.

  In another aspect of the control device for an internal combustion engine, the discharge control means can discharge the fuel to the second fuel tank. In this case, since the alcohol concentration of the fuel in the second fuel tank is sufficiently high, phase separation occurs in the second fuel tank even if the fuel in the first fuel tank is discharged to the second fuel tank. It is thought not to.

  In another aspect of the control device for an internal combustion engine, the emission control means discharges the fuel so as to be used for combustion in the internal combustion engine, and the internal combustion engine is discharged when the fuel is discharged by the emission control means. Motor control means is provided for controlling the motor so that the difference between the output of the engine and the required output of the vehicle is compensated by the output of the motor. Thereby, the fuel in the phase comprised by the alcohol and water which are phase-separated can be appropriately discharged | emitted outside, suppressing the torque change resulting from discharge | emission of the fuel in a 1st fuel tank.

  In another aspect of the control device for an internal combustion engine, the stirring means for stirring the fuel in the first fuel tank when the phase separation occurs during cold start of the internal combustion engine, and the stirring Starting means for starting the internal combustion engine using the fuel in the first fuel tank after stirring by the means, and the discharge control means has the phase separation after starting by the starting means In some cases, the fuel is discharged. In this case, the first fuel tank is agitated and the fuel in the phase composed of the alcohol and water in the first fuel tank is discharged to the outside. Therefore, it is possible to perform an appropriate start-up even during a cold start.

  Preferably, the control device for the internal combustion engine further includes fuel supply means for supplying the fuel in the second fuel tank to the first fuel tank during the stirring by the stirring means. In this case, the control for increasing the alcohol concentration in the first fuel tank is performed by supplying the fuel in the second fuel tank to the first fuel tank. This also makes it possible to properly eliminate the phase separation that occurs in the first fuel tank.

  More preferably, the apparatus further includes a heating unit that heats the first fuel tank during the stirring by the stirring unit. In this case, control for increasing the temperature of the fuel in the first fuel tank is performed. This also makes it possible to properly eliminate the phase separation that occurs in the first fuel tank.

  Preferably, the apparatus includes a discharge end determination unit that determines whether or not to end the discharge of the fuel by the discharge control unit, and the discharge control unit determines that the discharge end determination unit should end the discharge If so, the discharge ends. Thereby, it is possible to prevent wasteful discharge of gasoline in the first fuel tank.

  In the above case, the discharge end determination means calculates the amount of fuel to be discharged by the discharge control means based on the position of the boundary surface of the phase separation, and the discharge control means discharges the calculated fuel amount In this case, it can be determined that the discharge should be terminated. Further, the discharge end determination means can determine that the discharge should be ended when the position of the boundary surface of the phase separation is located below the position of the fuel suction port.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
First, a first embodiment of the present invention will be described.

(overall structure)
FIG. 1 is a schematic configuration diagram of a vehicle to which a control device for an internal combustion engine according to a first embodiment is applied. In FIG. 1, solid arrows indicate the flow of gas or fuel, and broken arrows indicate input / output of signals.

  An intake passage 2 is connected in the engine (internal combustion engine) 4, and intake air whose flow rate is adjusted by a throttle valve 3 provided on the intake passage 2 is introduced. Further, a high concentration side injector 14 and a low concentration side injector 24 are provided on the intake passage 2, and fuel is supplied from these. The engine 4 generates power by combusting a mixture of supplied intake air and fuel. The engine 4 then discharges the exhaust generated by the combustion into the exhaust passage 5.

  The high concentration side injector 14 and the low concentration side injector 24 are connected to the fuel supply passages 13 and 23, respectively. The fuel in the fuel tank 11 flows through the fuel supply passage 13, and the fuel in the fuel tank 21 flows through the fuel supply passage 23. The high-concentration side tank 11 and the low-concentration side tank 21 store fuels 19 and 29 obtained by mixing gasoline and alcohol such as methanol or ethanol, respectively. Specifically, the fuel 19 in the high concentration side tank 11 has a higher alcohol concentration than the fuel 29 in the low concentration side tank 21. For example, the high concentration side tank 11 stores fuel 19 having an alcohol concentration of about “E80 to E100”, and the low concentration side tank 21 stores fuel 29 having an alcohol concentration of about “E3 to E22”. Yes.

  Pumps 12 and 22 are provided in the fuel supply passages 13 and 23, respectively. The fuels 19 and 29 in the high-concentration side tank 11 and the low-concentration side 21 are sucked by the operation of the pumps 12 and 22, respectively, so that the fuels 19 and 29 are injected from the high-concentration injector 14 and the low-concentration side 24. . The fuels 19 and 29 thus injected are supplied to the engine 4. Basically, the fuel 19 stored in the high-concentration side tank 11 is used during normal driving of the vehicle, and the fuel 29 stored in the low-concentration side tank 21 is used when starting the vehicle at a low temperature. The reason why the fuel 29 is used at the time of cold start is that the fuel 29 has a low alcohol concentration (in other words, a high gasoline concentration), and therefore has a better startability than the fuel 19. Thus, the high concentration side tank 11 functions as the second fuel tank in the present invention, and the low concentration side tank 21 functions as the first fuel tank in the present invention.

  Further, the low concentration side tank 21 is provided with a phase separation detection device 25 and a phase separation boundary surface detection device 26. In the low concentration side tank 21, the phase separation detection device 25 is a phase in which the fuel 29 is composed of a gasoline phase (hereinafter referred to as “gasoline phase”), alcohol and water (hereinafter referred to as “water-alcohol phase”). It is also detected whether or not the phases are separated. The phase separation boundary surface detection device 26 detects a boundary surface between the gasoline phase and the water-alcohol phase (hereinafter referred to as “phase separation boundary surface”) when phase separation occurs.

  Here, phase separation will be described with reference to FIG. As illustrated, the fuel 29 in the low concentration side tank 21 is phase-separated into a gasoline phase 29a and a water-alcohol phase 29b. The position indicated by the arrow 29c indicates the phase separation interface between the gasoline phase 29a and the water-alcohol phase 29b. Usually, since water and alcohol have a higher specific gravity than gasoline, the water-alcohol phase 29b accumulates below the gasoline phase 29a. Phase separation occurs, for example, when the fuel contains a certain amount or more of moisture. Such phase separation can be temporarily eliminated by stirring the fuel 29. However, when phase separation occurs due to the moisture contained in the fuel 29, the proportion of moisture contained in the fuel 29 does not change even if the fuel is stirred. Arise.

  Further, when the phase separation boundary surface 29c is positioned above the fuel suction port 23a in the fuel supply passage 23, the alcohol concentration in the fuel sucked from the fuel suction port 23a becomes considerably high, and the fuel suction. Water is also sucked from the mouth 23a. Therefore, when phase separation as shown in FIG. 2 occurs, there is a high possibility that combustion in the engine 4 becomes unstable at low temperature start using the fuel in the low concentration side tank 21. Therefore, the startability of the engine 4 tends to deteriorate. As described above, in the present embodiment, when the phase separation occurs, the fuel in the water-alcohol phase 29b is discharged in order to suppress the occurrence of problems due to the phase separation. In addition, when "the fuel in a water-alcohol phase" is used in this specification, it shall contain not only alcohol but water.

  Returning to FIG. 1, the phase separation detection device 25 and the phase separation boundary surface detection device 26 will be specifically described. The phase separation detection device 25 includes, for example, an alcohol concentration sensor provided on the bottom surface of the low concentration side tank 21 and an alcohol concentration sensor provided on a float that moves together with the oil level of the fuel 29, not shown. Is done. The phase separation detection device 25 can detect whether or not phase separation has occurred based on the difference between the alcohol concentrations detected by the two alcohol concentration sensors. Specifically, the phase separation detection device 25 determines that the fuel is phase-separated when there is a difference in the detected alcohol concentration. The phase separation detection device 25 supplies a signal indicating whether or not the phases are separated to the ECU 10a.

  The phase separation boundary surface detection device 25 includes, for example, a float (which is different from the above-described float) set larger than the specific gravity of gasoline and smaller than the specific gravity of alcohol. When the phase separation occurs, the float moves to the boundary surface (phase separation boundary surface) between the water-alcohol phase and the gasoline phase. In other words, the float floats on top of the water-alcohol phase. Therefore, the phase separation boundary surface detection device 25 can detect the phase separation boundary surface by detecting the position of the float. The phase separation boundary surface detection device 25 supplies a signal corresponding to the detected position of the phase separation boundary surface to the ECU 10a.

  The ECU (Engine Control Unit) 10a includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like. The ECU 10a performs various controls based on the detection signals of the various sensors described above. Specifically, in the first embodiment, the ECU 10a controls the pump 22 and the low concentration side injector 24 to control the low concentration side tank 21 when the phase separation detection device 25 determines that phase separation has occurred. Control for injecting the fuel 29 is executed. Specifically, when the phase separation boundary surface is located above the fuel suction port 23a and the load of the engine 4 is high, control is performed to inject the fuel 29 in the low concentration side tank 21. . The reason why such control is executed is to enable appropriate start using the fuel 29 in the low concentration side tank 21 by discharging the fuel in the water-alcohol phase generated by the phase separation to the outside. . Thus, ECU10a operate | moves as a control apparatus of the internal combustion engine in this invention. Specifically, the ECU 10a functions as a phase separation determination unit and a discharge control unit.

(Water-alcohol phase discharge treatment)
Next, the water-alcohol phase discharge process according to the first embodiment will be described. This process is performed to discharge the water-alcohol phase fuel in the low-concentration side tank 21 when phase separation occurs and a predetermined condition is satisfied.

  FIG. 3 is a flowchart showing a water-alcohol phase discharge process according to the first embodiment. This process is repeatedly executed by the ECU 10a at a predetermined cycle. The water-alcohol phase discharge process is basically performed during normal operation after warming up.

  First, in step S <b> 101, the ECU 10 a determines whether or not phase separation occurs in the low concentration side tank 21. In this case, the ECU 10a makes a determination based on the detection signal supplied from the phase separation detection device 25. In addition, it is preferable to detect the phase separation when the vehicle is stopped. This is because the phase separation can be detected with higher accuracy when the vehicle is stopped. If phase separation has occurred (step S101; Yes), the process proceeds to step S102. If phase separation has not occurred (step S101; No), the process exits the flow.

  In step S102, the ECU 10a determines whether or not the phase separation boundary surface is located above the fuel suction port 23a. In this case, the ECU 10a makes a determination based on the detection signal supplied from the phase separation boundary surface detection device 26. When the phase separation boundary surface is located above the fuel suction port 23a (step S102; Yes), the process proceeds to step S103 because the fuel in the water-alcohol phase can be sucked from the fuel suction port 23a. In this case, when a predetermined condition is further satisfied, a process for discharging the water-alcohol phase fuel is executed. On the other hand, when the phase separation interface is located below the fuel suction port 23a (step S102; No), the process cannot be performed because the fuel in the water-alcohol phase cannot be sucked from the fuel suction port 23a. Exit the flow. In this case, although phase separation has occurred, fuel having a high gasoline concentration in the gasoline phase can be sucked from the fuel suction port 23a, and therefore, it is unlikely that the startability is deteriorated. It is not necessary to discharge the fuel inside.

  In step S103, the ECU 10a determines whether or not the load of the engine 4 is higher than a threshold value. That is, it is determined whether or not the load on the engine 4 is high. When the load of the engine 4 is high, even if the fuel 29 in the low-concentration side tank 21 is supplied to the engine 4, the ratio of water and alcohol to the entire injection amount is small. The effect is small. Therefore, in the present embodiment, when the load of the engine 4 is high, the water-alcohol phase fuel is discharged. The ECU 10a performs the determination in step S103 based on the output of a rotation speed sensor or the like provided in the engine 4. If the load on the engine 4 is higher than the threshold (step S103; Yes), the process proceeds to step S104. If the load on the engine 4 is equal to or less than the threshold (step S103; No), the process exits the flow.

  In step S104, the ECU 10a injects fuel in the low concentration side tank 21 by controlling the pump 22 and the low concentration side injector 24. That is, the fuel in the water-alcohol phase in the low concentration side tank 21 is discharged. Then, the process proceeds to step S105.

  In step S105, the ECU 10a determines whether or not the integrated injection amount from the low concentration side tank 21 has exceeded the required fuel consumption amount. That is, in step S105, the ECU 10a determines whether or not the discharge of the water-alcohol phase may be terminated. The required fuel consumption is calculated from the position of the phase separation boundary surface when the vehicle is stopped. Specifically, the required fuel consumption corresponds to the amount of fuel to be injected before the position of the phase separation boundary surface is lowered to the position of the fuel suction port 23a. Therefore, when the integrated injection amount reaches the required fuel consumption amount, the position of the phase separation boundary surface coincides with the position of the fuel suction port 23a.

  When the integrated injection amount exceeds the required fuel consumption (step S105; Yes), the process exits the flow. That is, the ECU 10a finishes discharging the water-alcohol phase. As described above, by determining the end of discharge using the necessary fuel consumption, it is possible to prevent the gasoline in the low concentration side tank 21 from being discharged wastefully. On the other hand, when the integrated injection amount does not exceed the required fuel consumption (step S105; No), the process returns to step S104. In this case, the fuel discharge in the water-alcohol phase is continued until the integrated injection amount exceeds the required fuel consumption.

  Thus, according to the water-alcohol phase discharge process according to the first embodiment, the water-alcohol phase fuel in the low concentration side tank 21 can be appropriately discharged to the outside. Thereby, it is possible to eliminate the phase separation occurring in the low concentration side tank 21 by reducing the ratio of moisture in the fuel 29 in the low concentration side tank 21. Further, since the position of the phase separation boundary surface is lower than the position of the fuel suction port 23a, when the fuel in the low concentration side tank 21 is used at the time of start-up, fuel having a high gasoline concentration (ie, gasoline phase fuel). Can be supplied to the engine 4. Therefore, according to the first embodiment, it is possible to perform an appropriate start using the fuel 29 in the low concentration side tank 21.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the second embodiment, similarly to the first embodiment, the water-alcohol phase discharge process is executed when phase separation occurs. However, the second embodiment differs from the first embodiment in that the control device for the internal combustion engine is applied to a hybrid vehicle. Specifically, in the second embodiment, the difference between the required output of the vehicle and the output of the engine 4 when the water-alcohol phase is discharged, in other words, before and after fuel injection in the water-alcohol phase. Control for compensating for the output change (torque change) by the output of the motor of the hybrid vehicle is performed.

(overall structure)
FIG. 4 is a schematic configuration diagram of a vehicle to which the control device for an internal combustion engine according to the second embodiment is applied. In FIG. 4, solid arrows indicate the flow of gas or fuel, and broken arrows indicate input / output of signals. Below, the same code | symbol is attached | subjected to the component same as 1st Embodiment, and the description is abbreviate | omitted.

  The vehicle according to the second embodiment is different from the vehicle according to the first embodiment in that the vehicle (motor generator) MG1, the motor MG2, the planetary gear 30, the inverter 31, and the battery 32 are provided. Moreover, it has ECU10b instead of ECU10a. Thus, the vehicle according to the second embodiment is configured as a hybrid vehicle.

  The motor MG1 is configured to function as a generator for charging the battery 32 or a generator for supplying power to the motor MG2. The motor MG2 is mainly configured to function as an electric motor that assists the output of the engine 4. Planetary gear 30 is configured to be able to distribute the output of engine 4 to motor MG1 and an axle (not shown). Inverter 31 is a DC / AC converter that controls input / output of electric power between battery 32 and motors MG1 and MG2. The battery 32 is a rechargeable storage battery configured to be able to function as a power source for driving the motor MG1 and the motor MG2.

  The ECU 10b includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like. Like the ECU 10a according to the first embodiment, the ECU 10b controls the pump 22 and the low concentration side injector 24 to control the low concentration side tank when the phase separation detection device 25 determines that phase separation has occurred. The control which discharges the water-alcohol phase in 21 is performed. However, the ECU 10b is different from the ECU 10a in that the ECU 10b performs control for compensating for the output change before and after the injection of the water-alcohol phase fuel by the output of the motor MG2. By executing such control, it is possible to appropriately suppress the output reduction in the vehicle due to the discharge of the water-alcohol phase fuel.

(Water-alcohol phase discharge treatment)
Here, the water-alcohol phase discharge process according to the second embodiment will be described. Also in the second embodiment, when phase separation occurs in the low concentration side tank 21, a process for discharging the fuel in the water-alcohol phase in the low concentration side tank 21 is performed. Further, in the second embodiment, a process of supplementing the output change before and after the injection of the water-alcohol phase fuel with the output of the motor MG2 is executed. Furthermore, in the second embodiment, the fuel injection amount in the water-alcohol phase is increased within a range where the output change due to the fuel-injection of the water-alcohol phase does not exceed a predetermined value. Also in this case, a process of compensating for the output change due to the increase in the fuel injection amount in the water-alcohol phase by the output of the motor MG2 is executed. The reason for increasing the fuel injection amount in this way is to increase the fuel discharge rate in the water-alcohol phase.

  Here, the water-alcohol phase discharge process according to the second embodiment will be specifically described with reference to FIG. FIG. 5A is a graph showing the presence or absence of phase separation, FIG. 5B is a graph showing the load of the engine 4, and FIG. 5C is a fuel injection amount from the low concentration side injector 24 (here) Is a graph showing a water-alcohol phase fuel discharge amount. 5D shows the detected torque of the motor MG1, FIG. 5E shows the generated torque of the motor MG2, and FIG. 5F shows the integrated injection amount from the low concentration side injector 24. Is shown. In addition, time is shown on the horizontal axis of Fig.5 (a)-(f).

  As shown in FIG. 5A, at time t10, the phase separation detection device 25 detects phase separation. And as shown in FIG.5 (b), the load of the engine 4 exceeds the threshold value X1 in the time t11. Therefore, the ECU 10b starts injection of fuel in the low concentration side tank 21 (fuel in the water-alcohol phase) as shown in FIG. In this case, the ECU 10b calculates the torque (output) of the engine 4 based on the output of the motor MG1, and within a range in which the torque change before and after fuel injection in the water-alcohol phase does not exceed a predetermined value, FIG. ) The amount of fuel injected from the low-concentration side tank 21 is gradually increased as indicated by the arrow Y1 in FIG. Thereby, the fuel in the water-alcohol phase can be quickly discharged.

  By injecting the fuel in the low-concentration side tank 21 in this way, the torque of the engine 4 detected based on the output of the motor MG1 is reduced as indicated by the arrow Y2 in FIG. Specifically, since the fuel injection amount in the water-alcohol phase is increased, the torque of the engine 4 is reduced accordingly. Therefore, ECU 10b performs control for generating torque from motor MG2 so that the torque change of engine 4 before and after fuel injection in the water-alcohol phase is compensated. Specifically, as indicated by an arrow Y3 in FIG. 5E, the ECU 10b increases the torque generated from the motor MG2 in accordance with the decrease in the torque of the engine 4. Then, as shown in FIG. 5 (f), at time t13, the integrated injection amount reaches the required fuel consumption amount X2. Therefore, the ECU 10b finishes discharging the fuel in the water-alcohol phase.

  FIG. 6 is a flowchart showing a water-alcohol phase discharge process according to the second embodiment. This process is repeatedly executed by the ECU 10b at a predetermined cycle.

  Since the process of step S201-S204 is the same as the process of step S101-S104 in the water-alcohol phase discharge process which concerns on 1st Embodiment (refer FIG. 3), the description is abbreviate | omitted. In the following, the processing after step S205 will be described.

  In step S205, the ECU 10b performs control for shifting the engine 4 to a steady state. In this case, the ECU 10b controls the motor MG2 to supplement the excess / deficiency with respect to the required torque with the torque generated by the motor MG2. Thus, by injecting the fuel in the low concentration side tank 21 in the steady state, it is possible to accurately calculate the torque change before and after the injection from the output of the motor MG1. When the process of step S205 ends, the process proceeds to step S206.

  In step S206, the ECU 10b determines whether or not the torque change before and after fuel injection in the low concentration side tank 21 is less than a threshold value. Here, the ECU 10b determines whether or not the fuel injection amount in the low concentration side tank 21 may be increased. In this case, the ECU 10b calculates a torque change based on the output of the motor MG1. The threshold used in step S206 is preferably set based on the state of charge (SOC) of battery 32. This is because the torque that the motor MG2 can output is determined according to the state of charge of the battery 32. That is, according to the state of charge of the battery 32, the generated torque of MG2 that can compensate for the torque change before and after fuel injection in the low concentration side tank 21 is determined.

  If the torque change is less than the threshold value (step S206; Yes), the process proceeds to step S207. In this case, since there is no problem even if the fuel injection amount in the low concentration side tank 21 is increased, in step S207, the ECU 10b increases the fuel injection amount. Thereby, the fuel in the water-alcohol phase can be quickly discharged. Then, the process proceeds to step S208. On the other hand, when the torque change is equal to or greater than the threshold value (step S206; No), the fuel injection amount in the low-concentration side tank 21 should not be increased. Therefore, the process proceeds to step S208 without increasing the fuel injection amount. Proceed to

  In step S208, the ECU 10b generates torque by controlling the motor MG2, that is, executes motor assist. Specifically, the ECU 10b generates torque from the motor MG2 so that the torque change of the engine 4 caused by fuel injection in the low concentration side tank 21 is compensated. Then, the process proceeds to step S209.

  In step S209, the ECU 10b determines whether or not the integrated injection amount from the low concentration side tank 21 exceeds the required fuel consumption amount. That is, it is determined whether or not the discharge of the water-alcohol phase may be terminated. If the integrated injection amount exceeds the required fuel consumption (step S209; Yes), the process exits the flow. That is, the ECU 10b finishes discharging the water-alcohol phase fuel. On the other hand, when the integrated injection amount does not exceed the required fuel consumption (step S209; No), the process returns to step S209. In this case, the water-alcohol phase fuel is continuously discharged until the integrated injection amount exceeds the required fuel consumption.

  As described above, according to the water-alcohol phase discharge process according to the second embodiment, the water-alcohol phase is appropriately removed from the outside while suppressing the torque change caused by the discharge of the water-alcohol phase in the low concentration side tank 21. Can be discharged. Moreover, according to 2nd Embodiment, the water-alcohol phase in the low concentration side tank 21 can be discharged | emitted rapidly.

  In the second embodiment, when the fuel is discharged in the water-alcohol phase, the operation line indicating the relationship between the engine speed and the load is changed to a low rotation and high load side than during normal operation. Is preferred. Specifically, as shown in FIG. 7, the operation line 71 used at the time of discharging the water-alcohol phase is set on the lower rotation and higher load side than the operation line 70 used during normal operation. In FIG. 7, the horizontal axis indicates the engine speed, and the vertical axis indicates the load of the engine 4. By setting the operation line in this way, when the fuel in the water-alcohol phase is injected, the ratio of water and alcohol in the entire injection amount can be further reduced, so that the influence on the output of the engine 4 is affected. It becomes possible to suppress effectively.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the third embodiment, similarly to the first embodiment and the second embodiment, the water-alcohol phase discharge process is executed when phase separation occurs. However, the third embodiment differs from the first and second embodiments in that water-alcohol phase fuel is discharged into the exhaust passage 5 of the engine 4 instead of being discharged into the intake passage 3.

(overall structure)
FIG. 8 is a schematic configuration diagram of a vehicle to which the control device for an internal combustion engine according to the third embodiment is applied. In FIG. 8, solid arrows indicate the flow of gas and fuel, and broken arrows indicate input / output of signals. Below, the same code | symbol is attached | subjected to the component same as 1st Embodiment, and the description is abbreviate | omitted.

The vehicle according to the third embodiment is the first in that it includes an exhaust side fuel supply passage 23b, a three-way valve 41, an exhaust side injector 42, a catalyst 43, and an O ₂ sensor (oxygen concentration sensor) 44. The configuration differs from the vehicle according to the embodiment. Moreover, it has ECU10c instead of ECU10a.

  The exhaust side fuel supply passage 23 b is connected to the fuel supply passage 23 via a three-way valve 41. In this case, the exhaust-side fuel supply passage 23 b can be connected to the fuel supply passage 23 by switching the three-way valve 41. The exhaust side fuel supply passage 23 b is connected to an exhaust side injector 42 provided on the exhaust passage 5. Therefore, when the three-way valve 41 is switched to connect the fuel supply passage 23 and the exhaust side fuel supply passage 23b, fuel is injected from the exhaust side injector 42 into the exhaust passage 5. That is, the fuel in the low concentration side tank 21 is injected into the exhaust passage 5.

The exhaust-side injector 42 is provided on the exhaust passage 5 on the upstream side of the catalyst 43 that can purify the exhaust gas. The exhaust side injector 42 is provided at such a position in order to purify the fuel injected from the exhaust side injector 42 by the catalyst 43. Further, an O ₂ sensor 44 for detecting the oxygen concentration is provided on the exhaust passage 5 on the downstream side of the catalyst 43.

  The ECU 10c includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like. Similar to the ECU 10a according to the first embodiment, the ECU 10c controls to discharge the water-alcohol phase fuel in the low-concentration side tank 21 when the phase separation detection device 25 determines that phase separation has occurred. Execute. However, the ECU 10 c is different from the ECU 10 a in that the water-alcohol phase fuel in the low concentration side tank 21 is discharged into the exhaust passage 5 by controlling the pump 22, the three-way valve 41, and the exhaust side injector 42. Different.

(Water-alcohol phase discharge treatment)
Next, the water-alcohol phase discharge process according to the third embodiment will be described. Also in the third embodiment, when phase separation occurs in the low concentration side tank 21, a process for discharging fuel in the water-alcohol phase in the low concentration side tank 21 is performed. Specifically, in the third embodiment, water-alcohol phase fuel is discharged into the exhaust passage 5.

  Furthermore, in the third embodiment, the air-fuel ratio is controlled so that the air-fuel ratio (A / F) in the catalyst 43 becomes stoichiometric. The reason for executing such control is as follows. Due to the fuel injection into the exhaust passage 5 as described above, the air-fuel ratio in the exhaust passage 5 tends to be rich. In this case, when the air-fuel ratio in the catalyst 43 becomes rich, the purification rate of the catalyst 43 tends to decrease as compared with the case where the air-fuel ratio is stoichiometric. Therefore, the ECU 10c increases the air-fuel ratio at the catalyst 43 by increasing the opening of the throttle valve 3 to make the air-fuel ratio at the outlet of the engine 4 lean while discharging the water-alcohol phase fuel. To maintain. Thereby, when the fuel in the water-alcohol phase is discharged, the air-fuel ratio in the catalyst 43 can be maintained in a stoichiometric manner, so that the purification rate of the catalyst 43 can be ensured.

  FIG. 9 is a flowchart showing a water-alcohol phase discharge process according to the third embodiment. This process is repeatedly executed by the ECU 10c at a predetermined cycle.

  Since the process of step S301 and S302 is the same as the process of step S101 and S102 in the water-alcohol phase discharge process which concerns on 1st Embodiment (refer FIG. 3), the description is abbreviate | omitted. Below, the process after step S303 is demonstrated.

  In step S303, the ECU 10c determines whether or not the catalyst 43 is warmed up. Here, when the water-alcohol phase fuel is discharged into the exhaust passage 5, the ECU 10c determines whether or not the catalyst 43 is in a state capable of purifying the fuel. If it is after the catalyst is warmed up (step S303; Yes), the process proceeds to step S304. If it is not after the catalyst is warmed up (step S303; No), the process exits the flow.

  In step S304, the ECU 10c injects the fuel in the low concentration side tank 21 by controlling the pump 22, the three-way valve 41, and the exhaust side injector 42. That is, the water-alcohol phase fuel in the low concentration side tank 21 is discharged into the exhaust passage 5. Then, the process proceeds to step S305.

In step S305, the ECU 10c determines whether or not the air-fuel ratio in the exhaust passage 5 downstream of the catalyst 43 is richly shifted. The determination in step S305 is performed to determine whether or not the control for returning the air-fuel ratio in the catalyst 43 to stoichiometric is to be executed. In this case, the ECU 10c makes a determination based on the detection signal supplied from the O ₂ sensor 44. If the air-fuel ratio has shifted to rich (step S305; Yes), the process proceeds to step S306. If the air-fuel ratio has not shifted to rich (step S305; No), the process proceeds to step S307.

  In step S306, the ECU 10c performs control to increase the opening of the throttle valve 3 (throttle opening) in order to make the air-fuel ratio of the catalyst 43 stoichiometric. That is, the air-fuel ratio at the outlet of the engine 4 is made lean by increasing the throttle opening. Thereby, since the air-fuel ratio of the catalyst 43 can be maintained at stoichiometric, the purification rate of the catalyst 43 can be ensured. The ECU 10c determines the throttle opening based on the fuel injection amount from the exhaust-side injector 42 and the like. When the process of step S306 ends, the process proceeds to step S307.

  In step S307, the ECU 10c determines whether or not the integrated injection amount from the low concentration side tank 21 exceeds the required fuel consumption amount. That is, it is determined whether or not the discharge of the water-alcohol phase may be terminated. If the integrated injection amount exceeds the required fuel consumption (step S307; Yes), the process exits the flow. That is, the ECU 10c finishes discharging the water-alcohol phase. On the other hand, when the integrated injection amount does not exceed the required fuel consumption (step S307; No), the process returns to step S305. In this case, the fuel injection in the low-concentration side tank 21 is continued while the process of maintaining the air-fuel ratio in the catalyst 43 at stoichiometric is performed until the integrated injection amount exceeds the required fuel consumption.

  Thus, according to the water-alcohol phase discharge process according to the third embodiment, the water-alcohol phase fuel can be appropriately discharged into the exhaust passage 5 while ensuring the purification rate of the catalyst 43 with respect to the exhaust gas. it can.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. Also in the fourth embodiment, the water-alcohol phase discharge process is executed when phase separation occurs as in the first embodiment. However, in the fourth embodiment, instead of discharging the water-alcohol phase fuel from the low concentration side tank 21 to the engine 4 or the exhaust passage 5, this water-alcohol phase fuel is discharged to the high concentration side tank 11. This is different from the first embodiment.

(overall structure)
FIG. 10 is a schematic configuration diagram of a vehicle to which the control device for an internal combustion engine according to the fourth embodiment is applied. In FIG. 10, solid line arrows indicate the flow of gas and fuel, and broken line arrows indicate signal input and output. Below, the same code | symbol is attached | subjected to the component same as 1st Embodiment, and the description is abbreviate | omitted.

  The vehicle according to the fourth embodiment is different from the vehicle according to the first embodiment in that it includes a fuel supply passage 50 and a pump 51. Moreover, it has ECU10d instead of ECU10a. The fuel supply passage 50 has one end (the fuel suction port 50 a) located in the low concentration side tank 21 and the other end located in the high concentration side tank 11. Inside the fuel supply passage 50, the fuel 29 in the low concentration side tank 21 sucked by the pump 51 flows as indicated by an arrow 90.

  Further, the fuel suction port 50 a of the fuel supply passage 50 is provided below the fuel suction port 23 a of the fuel supply passage 23 (on the bottom surface side of the low concentration side tank 21). Accordingly, the water-alcohol phase generated by the phase separation is sucked from the fuel suction port 50a and the position of the phase separation boundary surface is lowered, so that the phase separation boundary surface is positioned below the fuel suction port 23a. Can do. In other words, the phase separation boundary surface is located below the fuel suction port 50a, but the situation where the phase separation boundary surface is located above the fuel suction port 23a does not occur. Therefore, at the time of starting using the fuel 29 in the low concentration side tank 21, fuel with high gasoline concentration in the gasoline phase can be reliably sucked from the fuel suction port 23a, so that startability can be improved. .

  The ECU 10d includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like. Similar to the ECU 10a according to the first embodiment, the ECU 10d controls to discharge the water-alcohol phase fuel in the low-concentration side tank 21 when the phase separation detection device 25 determines that phase separation has occurred. Execute. However, the ECU 10 d is different from the ECU 10 a in that the water-alcohol phase fuel in the low concentration side tank 21 is discharged to the high concentration side tank 11 by controlling the pump 51.

(Water-alcohol phase discharge treatment)
Next, the water-alcohol phase discharge process according to the fourth embodiment will be described. Also in the fourth embodiment, when phase separation occurs in the low concentration side tank 21, a process for discharging the fuel in the water-alcohol phase in the low concentration side tank 21 is performed. Specifically, in the fourth embodiment, the water-alcohol phase fuel is discharged to the high concentration side tank 11. Also by this, it is possible to appropriately solve the problems such as the deterioration of the startability due to the phase separation as described above. In addition, since the alcohol concentration of the fuel 19 in the high concentration side tank 11 is sufficiently high, phase separation does not occur in the high concentration side tank 11 even if the water-alcohol phase fuel is discharged to the high concentration side tank 11. Conceivable.

  FIG. 11 is a flowchart showing a water-alcohol phase discharge process according to the fourth embodiment. This process is repeatedly executed by the ECU 10d at a predetermined cycle.

  In step S401, the ECU 10d determines whether or not the vehicle is stopped. When the vehicle is stopped, the determination in step S401 is performed because processing such as phase separation detection and phase separation boundary surface detection can be performed with high accuracy. If the vehicle is stopped (step S401; Yes), the process proceeds to step S402. If the vehicle is not stopped (step S401; No), the process exits the flow.

  In step S402, the ECU 10d determines whether or not phase separation occurs in the low concentration side tank 21. In this case, the ECU 10d makes a determination based on the detection signal supplied from the phase separation detection device 25. If phase separation has occurred (step S402; Yes), the process proceeds to step S403. If phase separation has not occurred (step S402; No), the process exits the flow.

  In step S403, the ECU 10d determines whether or not the phase separation boundary surface is located above the fuel suction port 23a. In this case, the ECU 10d makes a determination based on the detection signal supplied from the phase separation boundary surface detection device 26. When the phase separation boundary surface is located above the fuel suction port 23a (step S403; Yes), the fuel in the water-alcohol phase is sucked from the fuel suction port 23a, so the position of the phase separation boundary surface is lowered. In order to do so, the process proceeds to step S404. On the other hand, when the phase separation interface is located below the fuel suction port 23a (step S403; No), the fuel in the gasoline phase can be sucked from the fuel suction port 23a (in the water-alcohol phase). The process exits the flow because the fuel is much less likely to be aspirated). In this case, it is not necessary to lower the position of the phase separation interface.

  In step S <b> 404, the ECU 10 d supplies the fuel in the low concentration side tank 21 to the high concentration side tank 11 by controlling the pump 51. That is, the fuel is discharged by sucking the fuel in the water-alcohol phase in the low concentration side tank 21 from the fuel suction port 50a. Then, the process proceeds to step S405.

  In step S405, the ECU 10d determines whether or not the phase separation boundary surface is located below the fuel suction port 23a. Also in this case, the ECU 10d makes a determination based on the detection signal supplied from the phase separation boundary surface detection device 26.

  When the phase separation boundary surface is located below the fuel suction port 23a (step S405; Yes), the process proceeds to step S406 because the fuel in the gasoline phase can be sucked from the fuel suction port 23a. In this case, in step S406, the ECU 10d stops the supply of fuel to the high concentration side tank 11. That is, the ECU 10d finishes discharging the fuel in the water-alcohol phase of the low concentration side tank 21. Then, the process exits the flow. On the other hand, when the phase separation boundary surface is located above the fuel suction port 23a (step S405; No), the fuel in the water-alcohol phase is sucked from the fuel suction port 23a. In order to lower the position, the process of step S404 is executed again. That is, the ECU 10d continues to discharge the water-alcohol phase.

  Thus, the water-alcohol phase discharge process according to the fourth embodiment can appropriately discharge the water-alcohol phase fuel in the low concentration side tank 21 to the outside. Therefore, according to the third embodiment, it is possible to perform appropriate start-up using the fuel 29 in the low concentration side tank 21.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. Also in the fifth embodiment, the water-alcohol phase discharge process is executed when phase separation occurs as in the first embodiment. However, in the fifth embodiment, when phase separation occurs during cold start, the engine 4 is started after stirring the low-concentration side tank 21, and when phase separation occurs after the start of startup. It differs from 1st Embodiment etc. by the point which performs control which discharges the fuel of a water-alcohol phase.

(overall structure)
FIG. 12 is a schematic configuration diagram of a vehicle to which the control device for an internal combustion engine according to the fifth embodiment is applied. In FIG. 12, solid arrows indicate the flow of gas and fuel, and broken arrows indicate input / output of signals. Below, the same code | symbol is attached | subjected to the component same as 1st Embodiment, and the description is abbreviate | omitted.

  The vehicle according to the fifth embodiment is different from the vehicle according to the first embodiment in that it includes an agitation device 65 and includes an ECU 10e instead of the ECU 10a. The stirrer 65 is provided in the low concentration side tank 21 and includes, for example, a pump and a fuel circulation passage (not shown). In the fuel circulation passage, the fuel 29 in the low concentration side tank 21 circulates by the operation of the pump. One end of the fuel circulation passage is provided near the bottom surface portion of the low concentration side tank 21, and the other end of the fuel circulation passage is provided near the ceiling portion of the low concentration side tank 21. The fuel 29 in the low concentration side tank 21 is agitated by circulating the fuel 29 in the fuel circulation passage by the operation of the pump described above. The stirring device 65 is not limited to the above.

  The ECU 10e includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like. The ECU 10e executes control for discharging the water-alcohol phase fuel in the low concentration side tank 21 in the same manner as the ECU according to the first embodiment. Specifically, the ECU 10e starts the engine 4 after stirring the low-concentration tank 21 by controlling the stirring device 65 when phase separation occurs during the cold start, and after starting the phase separation Control is performed to discharge the water-alcohol phase fuel in the event that this occurs.

(Water-alcohol phase discharge treatment)
Next, the water-alcohol phase discharge process according to the fifth embodiment will be described. In the fifth embodiment, when phase separation occurs during cold start, the engine 4 is started after stirring the low-concentration side tank 21, and phase separation occurs after the start of such start. And a process for discharging the fuel in the water-alcohol phase.

  FIG. 13 is a flowchart showing a water-alcohol phase discharge process according to the fifth embodiment. This process is repeatedly executed by the ECU 10e at a predetermined cycle.

  First, in step S501, the ECU 10e determines whether or not there has been a start request when it is cold. If there is a start request during cold (step S501; Yes), the process proceeds to step S502. If there is no start request during cold (step S501; No), the process exits the flow. In step S <b> 502, the ECU 10 e determines whether phase separation has occurred in the low concentration side tank 21 based on the detection signal supplied from the phase separation detection device 25. If phase separation has occurred (step S502; Yes), the process proceeds to step S503. If phase separation has not occurred (step S502; No), the process exits the flow.

  In step S503, the ECU 10e agitates the low-concentration side tank 21 by controlling the agitation device 65. Since the phase separation is temporarily eliminated by stirring in this way, it is possible to suppress the suction of only the fuel in the water-alcohol phase from the fuel suction port 23a. Then, the process proceeds to step S504, and the ECU 10e starts the engine 4. Next, the process proceeds to step S505.

  In step S505, the ECU 10e determines again whether or not phase separation has occurred. If phase separation has occurred (step S505; Yes), the process proceeds to step S503. On the other hand, when phase separation has not occurred (step S505; No), the process returns to step S505. In this case, the determination in step S505 is repeated until phase separation is detected. This is because the ratio of moisture contained in the fuel 29 does not change greatly even if stirring is performed as described above, and phase separation occurs again after a certain amount of time has passed.

  In step S506, the ECU 10e controls the pump 22 and the low concentration side injector 24 to inject fuel in the low concentration side tank 21. That is, the fuel in the water-alcohol phase in the low concentration side tank 21 is discharged. Then, the process proceeds to step S507.

  In step S507, the ECU 10e determines whether or not the integrated injection amount from the low concentration side tank 21 exceeds the required fuel consumption amount. This required fuel consumption is calculated by the method described above. If the integrated injection amount exceeds the required fuel consumption (step S507; Yes), the process exits the flow. In this case, the discharge of the water-alcohol phase fuel is terminated. On the other hand, when the integrated injection amount does not exceed the required fuel consumption (step S507; No), the process returns to step S507. In this case, the water-alcohol phase fuel is continuously discharged.

  As described above, according to the water-alcohol phase discharge process according to the fifth embodiment, since the agitation of the low-concentration side tank 21 is performed at the time of cold start, appropriate start-up can be performed even at the time of cold start. After the engine is started, the water-alcohol phase fuel in the low concentration side tank 21 can be discharged to the outside.

  In the above description, the embodiment in which the fuel in the low concentration side tank 21 is injected into the engine 4 after the low concentration side tank 21 is agitated has been described. However, the present invention is not limited to this. In another example, after the low-concentration side tank 21 is stirred, the fuel in the low-concentration side tank 21 is injected into the exhaust passage 5 as shown in the third embodiment, instead of being injected into the engine 4. Alternatively, it can be injected into the high concentration side tank 11 as shown in the fourth embodiment. Further, when the control device for an internal combustion engine according to the fifth embodiment is applied to a hybrid vehicle, as shown in the second embodiment, the output change before and after the injection of the water-alcohol phase fuel is calculated. It is also possible to compensate by the output of the motor MG2.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. In the sixth embodiment, in order to increase the alcohol concentration in the low concentration side tank 21, control is performed to supply fuel in the high concentration side tank 11 to the low concentration side tank 21 in which phase separation has occurred. This is different from the first embodiment described above. This is because the phase separation of the low concentration side tank 21 can be eliminated by increasing the alcohol concentration of the low concentration side tank 21.

  FIG. 14 is a schematic configuration diagram of a vehicle to which the control device for an internal combustion engine according to the sixth embodiment is applied. In FIG. 14, solid arrows indicate the flow of gas and fuel, and broken arrows indicate input / output of signals. Below, the same code | symbol is attached | subjected to the component same as 1st Embodiment, and the description is abbreviate | omitted.

  The vehicle according to the sixth embodiment is different from the vehicle according to the first embodiment in that it includes a fuel supply passage 60, a pump 61, and a stirring device 65. Moreover, it has ECU10f instead of ECU10a. The fuel supply passage 60 has one end located in the low concentration side tank 21 and the other end located in the high concentration side tank 11. Inside the fuel supply passage 60, the fuel 19 in the high concentration side tank 11 sucked by the pump 61 flows as indicated by an arrow 91. Then, the fuel 19 flowing through the fuel supply passage 60 is supplied to the low concentration side tank 21. The agitator 65 is the same as that shown in the fifth embodiment described above, and agitates the fuel 29 in the low concentration side tank 21.

  The ECU 10f includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like. When phase separation has occurred, the ECU 10 f performs stirring by controlling the stirring device 65 and supplies fuel from the high concentration side tank 11 to the low concentration side tank 21 by controlling the pump 61.

  Here, the reason why fuel is supplied from the high concentration side tank 11 to the low concentration side tank 21 will be described with reference to FIG.

  FIG. 15 is a graph showing the relationship between the alcohol concentration (horizontal axis) and the water ratio causing the phase separation (vertical axis). From this, it can be seen that the higher the alcohol concentration, the greater the proportion of water that causes phase separation. That is, it can be said that the higher the alcohol concentration is, the higher the water ratio necessary for phase separation is, so that phase separation is less likely to occur. As described above, in the sixth embodiment, in order to eliminate the phase separation occurring in the low concentration side tank 21 by increasing the alcohol concentration in the low concentration side tank 21, a high alcohol concentration fuel is stored. Fuel is supplied from the concentration side tank 11 to the low concentration side tank 21.

  Next, processing according to the sixth embodiment will be described. FIG. 16 is a flowchart showing processing according to the sixth embodiment. This process is repeatedly executed by the ECU 10f at a predetermined cycle.

  In step S601, the ECU 10d determines whether or not the vehicle is stopped. If the vehicle is stopped (step S601; Yes), the process proceeds to step S602. If the vehicle is not stopped (step S601; No), the process exits the flow. In step S <b> 602, the ECU 10 d determines whether phase separation has occurred in the low concentration side tank 21 based on the detection signal supplied from the phase separation detection device 25. If phase separation has occurred (step S602; Yes), the process proceeds to step S603. If phase separation has not occurred (step S602; No), the process exits the flow.

  In step S <b> 603, the ECU 10 f supplies a predetermined amount of fuel from the high concentration side tank 11 to the low concentration side tank 21 by controlling the pump 61. This is because the alcohol concentration of the fuel in the low concentration side tank 21 is increased to eliminate the phase separation generated in the low concentration side tank 21. The predetermined amount of fuel supplied to the low-concentration side tank 21 is preferably set to such an amount that an increase in the alcohol concentration of the fuel in the low-concentration side tank 21 is suppressed as much as possible. This is because if the alcohol concentration of the fuel in the low concentration side tank 21 increases excessively, the startability may be deteriorated. When the process in step S603 is completed, the process proceeds to step S604.

  In step S604, the ECU 10f agitates the inside of the low concentration side tank 21 by controlling the agitation device 65. By performing such agitation, the supplied fuel, water and alcohol that are phase-separated can be effectively dissolved in the low-concentration side tank 21, and therefore phase separation can be quickly eliminated. Is possible. When the process of step S604 ends, the process proceeds to step S605.

  In step S605, the ECU 10f determines whether or not the phase separation has been canceled based on the detection signal supplied from the phase separation detection device 25. When the phase separation has been eliminated (step S605; Yes), the processing exits the flow. On the other hand, when the phase separation has not been eliminated (step S605; No), the process returns to step S603. In this case, the fuel supply to the low-concentration side tank 21 and the stirring of the fuel in the low-concentration side tank 21 are executed again.

  As described above, according to the sixth embodiment, the control of increasing the alcohol concentration in the low-concentration side tank 21 can appropriately eliminate the phase separation that occurs in the low-concentration side tank 21. Therefore, according to the sixth embodiment, it is possible to perform an appropriate start using the fuel 29 in the low concentration side tank 21.

  In the above description, the embodiment has been described in which only the control for supplying the fuel in the high concentration side tank 11 to the low concentration side tank 21 is performed. However, the embodiment is not limited thereto. In another example, control is performed to supply the fuel in the high concentration side tank 11 to the low concentration side tank 21 before the engine 1 is started, and after the engine 1 is started, the first to fourth embodiments described above are performed. Control of discharging the phase-separated water-alcohol phase fuel out of the low-concentration side tank 21 can be performed by any one of the embodiments. Thereby, it is possible to effectively eliminate the phase separation occurring in the low concentration side tank 21.

[Seventh Embodiment]
Next, a seventh embodiment of the present invention will be described. The seventh embodiment is different from the first embodiment described above in that control for increasing the temperature of the fuel in the low concentration side tank 21 is performed. This is because the phase separation of the low concentration side tank 21 can be eliminated by increasing the temperature of the fuel in the low concentration side tank 21.

  FIG. 17 is a schematic configuration diagram of a vehicle to which the control device for an internal combustion engine according to the seventh embodiment is applied. The control apparatus for an internal combustion engine according to the seventh embodiment is applied to a hybrid vehicle as in the second embodiment described above. Therefore, below, the same code | symbol is attached | subjected with respect to the component same as 2nd Embodiment, and the description is abbreviate | omitted. In FIG. 17, solid arrows indicate the flow of gas and fuel, and broken arrows indicate input / output of signals.

  The vehicle according to the seventh embodiment is different from the vehicle according to the second embodiment described above in that it includes heat transfer members 71, 72, and 73 and includes an ECU 10g instead of the ECU 10b. The heat transfer member 71 connects the motor MG1 and the low concentration side tank 21, the heat transfer member 72 connects the motor MG2 and the low concentration side tank 21, and the heat transfer member 73 includes the inverter 73 and the low concentration side. The tank 21 is connected. The heat transfer members 71, 72, 73 are made of metal having high thermal conductivity, and heat generated by the motor MG1, the motor MG2, and the inverter 73 (hereinafter also simply referred to as “motors”). It is configured to be able to transmit to the low concentration side tank 21.

  The ECU 10g includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like. The ECU 10g controls the motor MG2 before starting by the engine 4 when phase separation occurs at a low outside air temperature, thereby running using the torque generated by the motor MG2 (hereinafter referred to as “EV running”). )). That is, the ECU 10g causes the motors to generate heat by executing such EV traveling. By transmitting such heat generation to the low concentration side tank 21 via the heat transfer members 71, 72, 73, the low concentration side tank 21 can be heated. That is, the temperature of the fuel in the low concentration side tank 21 can be raised.

  Here, the reason why the temperature of the fuel in the low concentration side tank 21 is increased will be described with reference to FIG.

  FIG. 18 is a graph showing the relationship between the fuel temperature (horizontal axis) and the water ratio (vertical axis) causing phase separation. From this, it can be seen that the higher the temperature of the fuel, the greater the proportion of moisture that causes phase separation. That is, it can be said that the higher the temperature of the fuel, the higher the proportion of water necessary for phase separation, so that phase separation is less likely to occur. As described above, in the seventh embodiment, the temperature of the fuel in the low concentration side tank 21 is increased in order to eliminate the phase separation occurring in the low concentration side tank 21.

  Next, processing according to the seventh embodiment will be described. FIG. 19 is a flowchart showing processing according to the seventh embodiment. This process is repeatedly executed by the ECU 10g at a predetermined cycle.

  First, in step S701, the ECU 10g determines whether or not phase separation has occurred in the low-concentration side tank 21 when the vehicle is parked based on a detection signal supplied from the phase separation detection device 25. If phase separation has occurred (step S701; Yes), the process proceeds to step S702. If phase separation has not occurred (step S701; No), the process exits the flow.

  In step S702, the ECU 10g determines whether or not there is a driving request at a low outside air temperature. Here, it is determined whether or not the engine 4 can be started. If there is an operation request (step S702; Yes), the process proceeds to step S703. In this case, it can be said that starting by the engine 4 is difficult. On the other hand, when there is no driving request (step S702; No), the process exits the flow.

  In step S703, the ECU 10g executes EV traveling by controlling the motor MG2. By executing such EV traveling, the motors generate heat. The heat generated by the motors is transmitted to the low concentration side tank 21 via the heat transfer members 71, 72, 73. Thereby, the low concentration side tank 21 will be heated. The reason why the process of step S703 as described above is executed is to eliminate the phase separation occurring in the low concentration side tank 21 by increasing the temperature of the fuel in the low concentration side tank 21. Then, the process proceeds to step S704.

  In step S704, the ECU 10g determines whether or not the phase separation has been eliminated based on the detection signal supplied from the phase separation detection device 25. If phase separation has been eliminated (step S704; Yes), the process proceeds to step S705. In this case, since phase separation has not occurred, there is no problem even if the fuel is started using the fuel in the low concentration side tank 21, so the ECU 10g starts the engine 4 (step S705). Then, the process exits the flow. On the other hand, when the phase separation has not been eliminated (step S704; No), the process returns to step S703. In this case, EV travel is continued until phase separation is eliminated.

  As described above, according to the seventh embodiment, it is possible to appropriately eliminate the phase separation generated in the low concentration side tank 21 by performing the control for increasing the temperature of the low concentration side tank 21. Therefore, according to the seventh embodiment, it is possible to perform an appropriate start using the fuel 29 in the low concentration side tank 21.

  In the above description, the heat transfer members 71, 72, 73 are used to transmit the heat generated by the motors to the low-concentration side tank 21, but the present invention is not limited to this. In another example, instead of using the heat transfer members 71, 72, and 73, the components in the vehicle are arranged so that the motors are brought into contact with the low-concentration side tank 21. Therefore, it can be transmitted to the low concentration side tank 21. In still another example, instead of using the heat transfer members 71, 72, 73, the heat generated by the inverter 31 can be transmitted to the low concentration side tank 21 using water for cooling the inverter 31.

  In the above description, the embodiment is shown in which only the control for increasing the temperature of the low concentration side tank 21 is performed. However, the present invention is not limited to this. In another example, control for increasing the temperature of the low-concentration side tank 21 is performed before the engine 1 is started, and any of the first to fourth embodiments described above is performed after the engine 1 is started. By the method, it is possible to control the phase-separated water-alcohol phase fuel to be discharged to the outside of the low concentration side tank 21. By executing such control, the phase separation occurring in the low concentration side tank 21 can be effectively eliminated.

  Furthermore, in another example, before starting the engine 1, it is possible to perform control for increasing the temperature of the low concentration side tank 21 and control for stirring the fuel in the low concentration side tank 21.

1 is a schematic configuration diagram of a vehicle to which a control device for an internal combustion engine according to a first embodiment is applied. It is a figure for demonstrating phase separation. It is a flowchart which shows the water-alcohol phase discharge process which concerns on 1st Embodiment. The schematic block diagram of the vehicle with which the control apparatus of the internal combustion engine which concerns on 2nd Embodiment was applied is shown. It is a figure for demonstrating the water-alcohol phase discharge process which concerns on 2nd Embodiment. It is a flowchart which shows the water-alcohol phase discharge process which concerns on 2nd Embodiment. In 2nd Embodiment, it is a figure which shows the operation line used at the time of discharge | emission of a water-alcohol phase. The schematic block diagram of the vehicle to which the control apparatus of the internal combustion engine which concerns on 3rd Embodiment was applied is shown. It is a flowchart which shows the water-alcohol phase discharge process which concerns on 3rd Embodiment. The schematic block diagram of the vehicle with which the control apparatus of the internal combustion engine which concerns on 4th Embodiment was applied is shown. It is a flowchart which shows the water-alcohol phase discharge process which concerns on 4th Embodiment. The schematic block diagram of the vehicle to which the control apparatus of the internal combustion engine which concerns on 5th Embodiment was applied is shown. It is a flowchart which shows the water-alcohol phase discharge process which concerns on 5th Embodiment. The schematic block diagram of the vehicle with which the control apparatus of the internal combustion engine which concerns on 6th Embodiment was applied is shown. It is a graph which shows the relationship between the alcohol concentration and the water | moisture content ratio which raise | generates a phase separation. It is a flowchart which shows the process which concerns on 6th Embodiment. The schematic block diagram of the vehicle to which the control apparatus of the internal combustion engine which concerns on 7th Embodiment was applied is shown. It is a graph which shows the relationship between the temperature of a fuel, and the moisture ratio which raise | generates a phase separation. It is a flowchart which shows the process which concerns on 7th Embodiment.

Explanation of symbols

3 Throttle valve 4 Engine 5 Exhaust passage 10a, 10b, 10c, 10d, 10e, 10f, 10g ECU
11 High Concentration Side Tank 12, 22 Pump 14 High Concentration Side Injector 21 Low Concentration Side Tank 24 Low Concentration Side Injector 25 Phase Separation Detection Device 26 Phase Separation Interface Detection Device MG1, MG2 Motor

Claims (10)

A first fuel tank for storing a mixed fuel of gasoline and alcohol, and a second fuel tank for storing a mixed fuel of gasoline and alcohol having a higher alcohol concentration than the first fuel tank; A control device for an internal combustion engine that controls an internal combustion engine having
Phase separation determination means for determining whether or not the mixed fuel is phase-separated into a phase of the gasoline and a phase composed of the alcohol and water in the first fuel tank;
When the phase separation determination means determines that the phase separation has occurred, the fuel in the phase constituted by the alcohol and water that are phase-separated is forcibly placed outside the first fuel tank. An internal combustion engine control apparatus comprising: a discharge control means for performing control for discharging.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the discharge control means discharges the fuel into an exhaust passage of the internal combustion engine.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the discharge control means discharges the fuel into the second fuel tank. The emission control means discharges the fuel so as to be used for combustion in the internal combustion engine,
Motor control means for controlling the motor so that the difference between the output of the internal combustion engine and the required output of the vehicle when the fuel is discharged by the discharge control means is supplemented by the output from the motor. The control apparatus for an internal combustion engine according to claim 1, wherein the control apparatus is an internal combustion engine. Agitation means for agitating the fuel in the first fuel tank when the phase separation occurs during a cold start of the internal combustion engine;
Starting means for starting the internal combustion engine using the fuel in the first fuel tank after stirring by the stirring means,
The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the discharge control means discharges the fuel when the phase separation occurs after the start by the start means. .   6. The control of the internal combustion engine according to claim 5, further comprising fuel supply means for supplying the fuel in the second fuel tank to the first fuel tank during execution of the stirring by the stirring means. apparatus.   The control device for an internal combustion engine according to claim 5, further comprising a heating unit that heats the first fuel tank during the stirring by the stirring unit. A discharge end determination means for determining whether or not to end the discharge of the fuel by the discharge control means;
The internal combustion engine according to any one of claims 1 to 7, wherein the discharge control means ends the discharge when the discharge end determination means determines that the discharge should be ended. Control device.   The discharge end determination means calculates the amount of fuel to be discharged by the discharge control means based on the position of the phase separation boundary surface, and the discharge control means discharges the calculated fuel amount when the discharge control means discharges the fuel amount. 9. The control apparatus for an internal combustion engine according to claim 8, wherein it is determined that the exhaust should be terminated.   The discharge end determination means determines that the discharge should be ended when the position of the boundary surface of the phase separation is positioned below the position of the fuel suction port. Control device for internal combustion engine.

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