JP2007315292A - Internal combustion engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply fuel of stable property to an internal combustion engine when starting the internal combustion engine, for example. <P>SOLUTION: The internal combustion engine control device controls the engine 100 which has a fuel tank 410 for storing gasoline and ethanol mixed fuel. The control device comprises a discharging means such as a pump 73 or discharge port 411 for discharging from the fuel tank 410 a water-ethanol phase 91b which is generated by the phase separation of the mixed fuel in the fuel tank 410, a fractionating device 600 for fractionating the discharged water-ethanol phase into a gas phase mainly containing ethanol and a liquid phase mainly containing water, and a return passage 815 for returning the gas phase from the fractionating device 600 to the fuel tank 410. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  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.

  Therefore, in Patent Document 1, in an internal combustion engine using such a mixed fuel, when phase separation occurs at the time of starting, the fuel mixing process (that is, stirring) is performed and the fuel is made uniform before starting. A technique for performing the above has been proposed.

JP-A-6-26414

  However, in the technique disclosed in Patent Document 1, phase separation can be solved immediately after the stirring is performed. However, since the proportion of moisture contained in the fuel does not change even after stirring, when a certain amount of time passes, There is a high probability that the separation will recur. For this reason, there is a technical problem that it is difficult to supply a mixed fuel having a stable property.

  The present invention has been made in view of, for example, the above-described problems, and is an internal combustion engine capable of properly eliminating phase separation generated in a fuel tank and supplying fuel with stable properties at the time of starting. It is an object to provide a control device.

  In order to solve the above problem, an internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus that controls an internal combustion engine that includes a fuel tank that stores a mixed fuel in which gasoline and alcohol are mixed. A discharge means for executing a discharge process for discharging the separated phase composed of the alcohol and water generated by phase separation of the mixed fuel in the fuel tank from the fuel tank; and the discharged separated phase, Fractionation means for performing fractional distillation for fractional distillation into a gas phase containing alcohol as a main component and a liquid phase containing water as a main component; and return means for returning the gas phase from the fractionation means to the fuel tank With.

  The “internal combustion engine” according to the present invention is a concept encompassing an engine that converts combustion of fuel into motive power, and refers to, for example, an engine that uses gasoline or the like as fuel. In the present invention, a mixed fuel in which gasoline and alcohol are mixed (that is, alcohol-mixed gasoline) is used as a fuel for the internal combustion engine. The mixed fuel is stored in a fuel tank. Such a mixed fuel has a phase composed of gasoline and a phase composed of alcohol and water (that is, a separated phase) when the alcohol concentration is low or when the mixed fuel contains a certain amount or more of water. In some cases, phase separation occurs. When both a phase composed of gasoline (more precisely, a phase composed of mixed fuel with high gasoline concentration) and a phase composed of alcohol and water exist in the fuel tank, the fuel tank When the fuel is supplied to the fuel, the alcohol concentration changes every moment, so there is a possibility that the fuel having a stable property cannot be supplied. As a result, for example, when the internal combustion engine is started, combustion of the internal combustion engine may become unstable or exhaust gas characteristics may be deteriorated.

  However, according to the control apparatus for an internal combustion engine according to the present invention, during the operation, first, before starting the internal combustion engine, the separated phase generated by the phase separation of the mixed fuel in the fuel tank is, for example, the bottom surface of the fuel tank. Discharged from the fuel tank to a separate phase storage tank for storing a separated phase, for example, by a discharge port provided in the discharge port, a discharge path connected to the discharge port, and a pump provided in the discharge path . Therefore, the separated phase can be removed from the fuel tank, that is, the phase separation can be eliminated. Next, the separation phase is heated to a predetermined distillation temperature or distillation temperature by the fractionation means, thereby being fractionated into a gas phase mainly composed of alcohol and a liquid phase mainly composed of water. The More specifically, the separation phase composed of, for example, ethanol and water as an example of an alcohol is heated to a predetermined distillation temperature set in advance, for example, to about 80 ° C. by the distillation means, It is separated into a gas phase mainly composed of ethanol having a lower boiling point and a liquid phase mainly composed of water having a boiling point higher than the distillation temperature. Under atmospheric pressure, ethanol has a boiling point of about 78 ° C. and water has a boiling point of about 100 ° C. Next, the gas phase (or the liquid in which the gas phase is condensed) is returned to the fuel tank by return means such as a return passage provided between the fractionation means and the fuel tank. Therefore, the gas phase mainly composed of alcohol can be mixed with the fuel in the fuel tank and dissolved in the phase composed of gasoline. Here, since the gas phase contains little or no water, there is little or no risk that phase separation will occur again by returning the gas phase to the fuel tank.

  Thus, ideally “fractionation treatment” according to the present invention is “gas phase mainly composed of ethanol”, “ethanol component is 80% or more by volume or weight%, preferably 90% or more, Divided into “a gas phase as close to 100% as possible” and “a liquid phase mainly composed of water” as “a liquid phase as close to 100% as possible, such as 80% or more, preferably 90% or more by volume or weight%” In a broad sense, the “concentration of the ethanol component in the gas phase” is higher than the “concentration of the ethanol component in the liquid phase” or the “concentration of water in the liquid phase” is This means that fractional distillation is performed so as to be higher than the “water concentration in the phase”. That is, in the broad sense, the above-described profit from fractional distillation can be greater or smaller depending on the degree of the fractional distillation. In an ideal case, the profit from the above-mentioned fractional distillation is significant and maximum. It will be obtained to the limit.

  As described above, according to the control apparatus for an internal combustion engine according to the present invention, the separation phase is discharged from the fuel tank by the discharge means, so that the phase separation in the fuel tank can be eliminated. Furthermore, after separating the separated phase discharged by the discharging means into a gas phase mainly composed of alcohol and a liquid phase mainly composed of water by the fractionation means, only the gas phase mainly composed of alcohol is obtained. Return to the fuel tank by return means. Therefore, the alcohol can be reliably dissolved again in the fuel in the fuel tank. Accordingly, it is possible to suppress or prevent deterioration of fuel properties due to phase separation that may occur in a mixed fuel in which gasoline and alcohol are mixed, and it becomes possible to supply fuel with stable properties to the internal combustion engine. As a result, it is possible to reduce or prevent the combustion of the internal combustion engine from becoming unstable or the exhaust gas characteristics from deteriorating, for example, at the start of the internal combustion engine.

  In one aspect of the control apparatus for an internal combustion engine according to the present invention, the fractionating means exchanges heat between the cooling water for the internal combustion engine that cools the internal combustion engine and the discharged separated phase. The fractionation process is performed using the temperature of the cooling water as the distillation temperature.

  According to this aspect, heat exchange is performed between the separated phase and the cooling water for the internal combustion engine by the fractionation means. Thereby, the separated phase is fractionated into a gas phase and a liquid phase using the temperature of the cooling water for the internal combustion engine as a distillation temperature. That is, a gas phase mainly containing ethanol having a boiling point lower than the water temperature of cooling water for an internal combustion engine, for example, about 80 ° C., by a fractionation means, for example, a separated phase composed of ethanol and water as an example of alcohol. And a liquid phase mainly containing water having a boiling point higher than the temperature of the cooling water for the internal combustion engine.

  In the aspect in which the fractionation means executes the fractionation process using the temperature of the cooling water for the internal combustion engine as the distillation temperature, the fractionation means is controlled to execute the fractionation process after the internal combustion engine is started. A fractionation control means may be further provided.

  In this case, the fractionation process is executed after the internal combustion engine is started or warmed up. That is, for example, the internal combustion engine cooling water, which is at a temperature lower than the boiling point of the alcohol at a low temperature or cold start, is heated by the heat generated by the internal combustion engine, and then the fractionation process is performed. Therefore, heat can be exchanged between the cooling water for the internal combustion engine, which has become a temperature higher than the boiling point of the alcohol contained in the separated phase, and the separated phase. Therefore, the separation phase can be reliably separated into a gas phase mainly composed of alcohol and a liquid phase mainly composed of water. The temperature of the cooling water for the internal combustion engine is typically about 80 ° C. due to heat radiation by the cooling device for the internal combustion engine.

  In another aspect of the control device for an internal combustion engine according to the present invention, the separated phase is determined by phase separation determining means for determining whether or not the separated phase is generated in the fuel tank, and by the phase separation determining means. When it is determined that the discharge has occurred, the apparatus further includes discharge control means for controlling the discharge means so as to execute the discharge process.

  According to this aspect, before starting the internal combustion engine, first, it is determined by the phase separation determination means having an alcohol concentration sensor or a water sensor, for example, whether or not a separated phase is generated, that is, in the fuel tank. It is determined whether the mixed fuel is phase-separated. Next, when it is determined that the phases are separated, the separated phase is discharged from the fuel tank by the discharge means under the control of the discharge control means. Thereby, the separated phase can be reliably removed from the fuel tank, in other words, the phase separation in the mixed fuel in the fuel tank can be surely eliminated.

  If it is determined that the phases are not separated, the discharge control means controls the discharge means so that the discharge process is not performed, thereby eliminating almost or completely the energy loss due to unnecessary discharge processing. Can do that.

  In another aspect of the control device for an internal combustion engine according to the present invention, the internal combustion engine is provided in a hybrid vehicle together with a motor generator, and at least during the period during which the exhaust process is performed, the hybrid vehicle travels. The apparatus further includes power switching means for switching the power source for the engine from the internal combustion engine to the motor generator.

  According to this aspect, the power source of the hybrid vehicle is switched to the motor generator during the period in which the discharge process for discharging the separated phase from the fuel tank is performed, that is, the EV traveling of the hybrid vehicle is executed. Therefore, the internal combustion engine can be started using fuel having a high gasoline concentration by switching the power source to the internal combustion engine after the exhaust processing is completed (that is, starting the internal combustion engine). Therefore, startability of the internal combustion engine can be ensured or improved.

  The “motor generator” according to the present invention converts the electrical energy supplied from the battery into mechanical energy, and functions as an electric motor, and converts the mechanical energy into electrical energy, for example, to a battery or the like. And a function of operating as a generator for supplying electric power. Two types of motor generators may be installed in advance: a motor generator mainly used as an electric motor (motor) and a motor generator mainly used as a generator (generator). In the “hybrid vehicle” according to the present invention including such an internal combustion engine and a motor generator, so-called parallel control is suitably performed in which the motor generator can assist the power of the internal combustion engine as appropriate.

  In the aspect further including the phase separation determination unit described above, the phase separation determination unit includes a water detection unit that detects whether or not water is contained in the fuel in the lower part of the fuel tank. Also good.

  In this case, a separated phase composed of alcohol and water (that is, containing water) can be detected by water detection means such as a water sensor provided on the bottom surface of the fuel tank. Furthermore, the separated phase formed in the lower part in the fuel tank can be reliably detected due to the fact that it consists of water having a higher specific gravity than gasoline and alcohol having a characteristic that it is easily dissolved in water. Therefore, it is possible to reliably determine whether or not a separated phase is generated by the phase separation determination means.

  In the aspect further including the phase separation determination unit described above, the phase separation determination unit may include an alcohol concentration detection unit that detects an alcohol concentration of the fuel in a lower portion in the fuel tank.

  In this case, for example, a separated phase composed of alcohol and water (that is, containing alcohol) can be detected by alcohol concentration detection means such as an alcohol sensor provided on the bottom surface of the fuel tank. Furthermore, the separated phase formed in the lower part in the fuel tank can be reliably detected due to the fact that it consists of water having a higher specific gravity than gasoline and alcohol having a characteristic that it is easily dissolved in water. Therefore, it is possible to reliably determine whether or not a separated phase is generated by the phase separation determination means.

  More specifically, the alcohol concentration detected by the alcohol concentration detection means when the phase separation does not occur, for example, when the mixed fuel is supplied to the fuel tank, and the determination by the phase separation determination means. If the difference from the alcohol concentration detected by the alcohol concentration detection means is, for example, a predetermined reference value or more, the phase separation determination means determines that a separated phase has occurred.

  In another aspect of the control apparatus for an internal combustion engine according to the present invention, the discharge means is provided on the bottom surface of the fuel tank and has a discharge port for discharging the separated phase.

  According to this aspect, the separation phase formed in the lower part in the fuel tank is caused to be separated from the water tank having a specific gravity higher than that of gasoline and the alcohol having the characteristic of being easily dissolved in water. It can discharge reliably by the discharge port provided in the bottom face.

  In another aspect of the control device for an internal combustion engine according to the present invention, the internal combustion engine further includes a separated phase storage tank for storing the separated phase, and the discharging means removes the separated phase from the fuel tank as the discharging process. It discharges | emits to a separated phase storage tank, and the said fractionation means performs the said fractionation process with respect to the separated phase stored by the said separated phase storage tank.

  According to this aspect, the separated phase discharged from the fuel tank by the discharging means can be stored in the separated phase storage tank. Therefore, the discharged separated phase can be fractionated by the fractionating means after being temporarily stored in the separated phase storage tank.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
A control device according to the first embodiment will be described with reference to FIGS. 1 to 3.

  First, the overall configuration of a control device according to the present embodiment and a hybrid vehicle equipped with the control device will be described with reference to FIG. FIG. 1 is a block diagram showing a main part of a control device according to this embodiment and a hybrid vehicle equipped with the control device.

  In FIG. 1, the hybrid vehicle 1 includes an engine 100, a motor generator 200, a radiator 510, an engine cooling water flow path 511, a fuel tank 410, a sub tank 420, a fractionation device 600, a return passage 815, and a control device 300.

  The engine 100 is an example of the “internal combustion engine” according to the present invention, the fuel tank 410 is an example of the “fuel tank” according to the present invention, and the sub tank 420 is the “separated phase storage tank” according to the present invention. The fractionation device 600 is an example of the “fractionation means” according to the present invention, and the return passage 815 is an example of the “return means” according to the present invention.

  The hybrid vehicle 1 is configured as a so-called parallel type hybrid vehicle in which an engine 100 and a motor generator 200 that functions as an electric motor and a generator are mounted as a driving source for traveling. Engine 100 and motor generator 200 are connected to each other via a transmission mechanism (not shown).

  The engine 100 has four cylinders (not shown), and is configured as a so-called four-cylinder engine. The engine 100 is configured to be able to drive the hybrid vehicle 1 by combusting the air-fuel mixture in the cylinders in each cylinder and converting the internal piston motion generated according to the explosive force into rotational motion. In the present embodiment, a mixed fuel in which gasoline and ethanol are mixed (that is, ethanol mixed gasoline) is used as the fuel of the engine 100, and combustion is possible even with 100% gasoline, and ethanol is mixed at an arbitrary ratio. Even if it is done, it can be burned.

  An intake pipe 130 upstream of the engine 100 is provided with an injector 120 for each cylinder. The injector 120 is connected to a fuel tank 410 described later, and injects fuel into the intake passage for each cylinder.

  The main body of the engine 100 is provided with an engine speed sensor 54 (hereinafter also referred to as “NE sensor”). The NE sensor 54 is provided in the vicinity of a cam crankshaft (not shown) of the engine 100 and generates a signal pulse (that is, a TDC pulse) at every predetermined rotation angle (180 degrees in the present embodiment) of the crankshaft. To supply. The control device 300 can calculate the engine speed based on the signal pulse from the NE sensor 54.

  An oxygen sensor 55 is provided in the exhaust pipe 140 downstream of the engine 100. The oxygen sensor 55 can detect the oxygen concentration in the exhaust gas in the exhaust pipe 140.

  The engine coolant flow path 511 is configured to be able to exchange heat between the engine 100 and the radiator 510. The cooling water (that is, engine cooling water) in the engine cooling water flow path 511 that cools the engine 100 that generates heat is heated when the engine 100 is cooled, but dissipates heat in the radiator 510, and the engine cooling water flow again. It will flow through the path 511. The engine coolant is circulated in the engine coolant channel 511 by a water pump (not shown) provided in the middle of the engine coolant channel 511. Further, a temperature sensor 58 is provided in the engine coolant flow path 511, and the coolant temperature of the engine coolant (that is, the engine coolant temperature) can be detected. The engine coolant temperature is set to about 80 ° C. due to heat radiation by the radiator 510.

  Motor generator 200 is connected to a battery (not shown) via an inverter (not shown), and power is appropriately transferred between motor generator 200 and the battery. The motor generator 200 functions as an electric motor by converting electric energy supplied from the battery into mechanical energy, and operates as a generator that supplies electric power to the battery by converting mechanical energy into electric energy. It has a function.

  The fuel tank 410 stores fuel 91 that is used for combustion of the engine 100. The fuel 91 stored in the fuel tank 410 is supplied by the pump 71 to the injector 120 via the fuel path 711.

  The bottom surface of the fuel tank 410 is provided with a phase separation determination device 51 as an example of “phase separation determination means” according to the present invention. In the fuel tank 410, the phase separation determination device 51 is also referred to as a phase in which the fuel 91 is composed of a gasoline phase (hereinafter referred to as “gasoline phase”), ethanol and water (hereinafter referred to as “water-ethanol phase”). ) And whether or not the phases are separated. In other words, it is possible to determine whether or not a water-ethanol phase is generated.

  Here, phase separation will be described with reference to FIG. FIG. 2 is a schematic diagram for explaining phase separation.

  As shown in FIG. 2, the fuel 91 in the fuel tank 410 is phase-separated into a gasoline phase 91a and a water-ethanol phase 91b as an example of the “separated phase” according to the present invention. The position indicated by the arrow 91c indicates the phase separation interface between the gasoline phase 91a and the water-ethanol phase 91b (that is, the interface between the gasoline phase and the water-ethanol phase when phase separation occurs). . Usually, water and ethanol have a higher specific gravity than gasoline, so that a water-ethanol phase 91b is accumulated below the gasoline phase 91a. 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 91. However, when phase separation occurs due to the moisture contained in the fuel 91, the proportion of moisture contained in the fuel 91 does not change even if the fuel is stirred. It will occur. Further, when the phase separation boundary surface 91c is positioned above the fuel suction port 711a in the fuel path 711, the alcohol concentration in the fuel sucked from the fuel suction port 711a becomes high, and the fuel suction port 711a. Moisture is also sucked from the water. Therefore, in the case where the phase separation as shown in FIG. 2 occurs, there is a possibility that the fuel having a stable property cannot be supplied from the fuel tank 410 to the engine 100 unless any countermeasure is taken. As a result, for example, when the engine 100 is started, combustion of the engine 100 may become unstable or exhaust gas characteristics may be deteriorated. However, in this embodiment, as will be described later, for example, when the engine 100 is started, the fuel in the fuel tank 410 is supplied to the engine 100 after the water-ethanol phase 91b is removed. Deterioration can be suppressed or prevented.

  In FIG. 1 again, the phase separation determination device 51 includes an alcohol sensor 51a as an example of the “alcohol concentration detection means” according to the present invention. The alcohol sensor 51 a detects the alcohol concentration of the fuel in the lower part in the fuel tank 410. The phase separation determination device 51 determines whether or not the water-ethanol phase 91b is generated in the fuel tank 410 as follows. That is, the alcohol concentration detected by the alcohol sensor 51a when phase separation does not occur, such as when fuel is supplied to the fuel tank 410, and the alcohol sensor 51a detected by the phase separation determination device 51. When there is a difference equal to or greater than the predetermined reference value in the alcohol concentration, the phase separation determination device 51 determines that the water-ethanol phase 91b is generated. Here, particularly in the present embodiment, the phase separation determination device 51 includes the alcohol sensor 51 a provided on the bottom surface of the fuel tank 410, so that the water-ethanol phase 91 b that has accumulated below the fuel tank 410 is reliably removed. Can be detected. Therefore, the phase separation determination device 51 can reliably determine whether or not the water-ethanol phase 91b is generated. The phase separation determination device 51 supplies a signal indicating whether or not the phases are separated to the control device 300.

  As a modification of the present embodiment, the phase separation determination device 51 may include a water sensor provided on the bottom surface of the fuel tank 410 instead of or in addition to the alcohol sensor 51a. Also in this case, the water-ethanol phase 91b accumulated under the fuel tank 410 can be reliably detected. Therefore, the phase separation determination device 51 can reliably determine whether or not the water-ethanol phase 91b is generated.

  The sub tank 420 is configured to be able to store a fuel 92 composed of a water-ethanol phase 91 b generated by phase separation of the fuel 91 in the fuel tank 410. More specifically, the water-ethanol phase 91b generated by phase separation of the fuel 91 in the fuel tank 410 is discharged to the sub tank 420 by the pump 73 via the discharge port 411 and the discharge paths 62 and 63, and the fuel. It is stored as 92. That is, the pump 73 is configured to suck out the water-ethanol phase 91b from the fuel tank 410 via the discharge port 411 and the discharge path 62, and send the water-ethanol phase 91b to the sub tank 420 via the discharge path 63. Has been.

  The pump 73, the discharge port 411, and the discharge paths 62 and 63 are examples of the “discharge means” according to the present invention.

  The fractionator 600 includes a heat exchanger 610, a fractionation passage 811, a gas phase passage 812, and a liquid phase passage 813.

  The fuel 92 stored in the sub tank 420 can be supplied to the heat exchanger 610 via the fractionation passage 811 by the pump 72.

  The heat exchanger 610 performs heat exchange between the fuel 92 supplied from the sub tank 420 via the fractionation passage 811 and the engine cooling water flowing through the engine cooling water flow path 511, so that the fuel 92 (that is, The water-ethanol phase 91b) is converted into a gas phase (ie, ethanol having a boiling point lower than about 80 ° C., for example, more than 50% by volume or weight%, with a distillation temperature of about 80 ° C., which is an engine coolant temperature. Preferably a gas primarily comprising 90% or more, etc.) and a liquid phase (ie, a liquid mainly comprising water having a boiling point higher than about 80 ° C., eg greater than 50% by volume or weight%, preferably 90% or more, etc.) And can be fractionally fractionated. That is, the heat exchanger 610 supplies the fuel 92 supplied from the fuel tank 410 via the fractionation passage 811 to the engine coolant flow path 511 on the outlet side of the radiator 510 (that is, the radiator 510 in the engine coolant flow path 511). It is configured to evaporate ethanol having a boiling point lower than the temperature of the engine coolant contained in the supplied fuel 92 by contacting with the portion where the engine coolant adjusted to about 80 ° C. flows. In other words, the heat exchanger 610 can separate the fuel 92 into ethanol and water by heating the fuel 92 (that is, the water-ethanol phase 91b) using the engine cooling water to evaporate the ethanol. It is configured.

  The heat exchanger 610 supplies the fuel supplied from the sub tank 410 via the fractionation passage 811 to the engine cooling water passage 511 on the outlet side of the engine 100 (that is, about 80 by the engine 100 in the engine cooling water passage 511). It may be configured such that ethanol having a boiling point lower than the engine coolant temperature contained in the supplied fuel is vaporized by contacting with a portion where the engine coolant having a temperature higher than ° C. flows. In this case, vaporization of ethanol contained in the fuel 92 can be promoted, and the fuel 92 can be easily fractionated into ethanol (ie, gas phase) and water (ie, liquid phase).

  The gas phase generated by fractional distillation by the heat exchanger 610 is configured to flow out to a gas phase passage 812 from a gas phase outlet (not shown) provided at an upper portion in the heat exchanger 610. On the other hand, the liquid phase generated by fractional distillation by the heat exchanger 610 is configured to flow out to a liquid phase passage 813 from a liquid phase outlet (not shown) provided in the lower part of the heat exchanger 610. The liquid phase passage 813 is configured to be able to guide the gas phase to a liquid phase tank (not shown).

  The return passage 815 is provided between the gas phase passage 812 and the fuel tank 410, and is configured to be able to guide the gas phase mainly composed of ethanol from the gas phase passage 812 to the fuel tank 410.

  The control device 300 includes a discharge control unit 310, a fractionation control unit 320, a fuel supply control unit 330, and a power switching unit 340, and controls the overall operation of the engine 100 and the motor generator 200. Here, the discharge control unit 310 is an example of the “discharge control unit” according to the present invention, the fractionation control unit 320 is an example of the “fractionation control unit” according to the present invention, and the power switching unit 340 includes: It is an example of "power switching means" according to the present invention. These are preferably a well-known electronic control unit (ECU), a central processing unit (CPU), a read only memory (ROM) storing a control program, and various data. It is configured as a logical operation circuit centering on a random read / write memory (RAM) to be stored. Further, the control device 300 is a bus (not shown) for an input port that receives input signals from various sensors such as the NE sensor 54 and the phase separation determination device 51 and an output port that sends control signals to various actuators such as the injector 120. Connected through.

  The discharge control unit 310 is configured to be able to control the pump 73. Particularly in the present embodiment, when the phase separation determination device 51 determines that the phases are separated (that is, the water-ethanol phase 91b is generated in the fuel tank 410), the discharge control unit 310 The pump 73 is controlled so as to perform a discharge process for discharging the water-ethanol phase 91b in the fuel tank 410 to the sub tank 420 via the discharge port 411 and the discharge paths 62 and 63. Therefore, after such a discharge process, the fuel tank 410 stores the fuel 91 from which the water-ethanol phase 91b has been removed (that is, the gasoline phase 91a), and the sub tank 420 includes the water-ethanol phase 91b. Fuel 92 will be stored.

  The fractionation control unit 320 is configured to be able to control the pump 72. In the present embodiment, in particular, the pump 72 is configured to control heat exchange by the heat exchanger 610 after the engine 100 is started or warmed up. Therefore, for example, after the engine coolant having a temperature lower than the boiling point of ethanol at a low temperature or during cold start is heated by the heat generated by the engine 100, heat exchange by the heat exchanger 610 is performed. Accordingly, heat can be exchanged between the engine cooling water that has reached a temperature higher than the boiling point of ethanol contained in the fuel 92 and the fuel 92. Therefore, the fuel 92 can be reliably separated into a gas phase mainly composed of ethanol and a liquid phase mainly composed of water.

  The fuel supply control unit 330 is configured to be able to control the pump 71 and the injector 120. More specifically, the fuel supply control unit 330 is configured to be able to control the fuel supply timing by the pump 71 and the fuel injection amount and injection timing by the injector 120.

  The power switching unit 340 is configured to be able to switch the power source of the hybrid vehicle 1 between the engine 100 and the motor generator 200. In the present embodiment, in particular, the power switching unit 340 switches the power source of the hybrid vehicle 1 to the motor generator 200 during the period in which the discharge process for discharging the water-ethanol phase 91b from the fuel tank 410 to the sub tank 420 is being performed. Is configured to be possible.

  Next, operation processing of the control device according to the present embodiment will be described with reference to FIG. 3 in addition to FIG. 1 and FIG. FIG. 3 is a flowchart showing the operation process of the control device according to this embodiment. Note that FIG. 3 mainly shows an operation process when the engine 100 is started.

  In FIG. 3, first, whether or not the fuel 91 in the fuel tank 410 is phase-separated by the phase separation determination device 51 (that is, whether or not the water-ethanol phase 91b is generated in the fuel tank 410). Determination is made (step S11). In other words, the alcohol concentration detected by the alcohol sensor 51a at the time of fuel supply to the fuel tank 410 (that is, when no phase separation occurs) and the alcohol sensor 51a at the time of determination by the phase separation determination device 51. It is determined whether or not there is a difference between the detected alcohol concentration and a predetermined reference value or more.

  If it is determined that the phases are not separated (that is, the water-ethanol phase 91b is not generated in the fuel tank 410) (step S11: NO), the engine 100 is used using the fuel 91 in the fuel tank 410. Is started (step S21). That is, the power switching unit 340 switches the power source of the hybrid vehicle 1 to the engine 100, and the fuel 91 in the fuel tank 410 is driven by the pump 71, the injector 120, and the like under the control of the fuel supply control unit 330. By being supplied to 100, the engine 100 is started. In this case, the pump 73 is not operated, and there is no energy loss due to unnecessary discharge processing.

  On the other hand, when it is determined that the phases are separated (that is, the water-ethanol phase 91b is generated in the fuel tank 410) (step S11: YES), the water-ethanol phase 91b in the fuel tank 410 is determined. Is discharged to the sub tank 420 (step S12). That is, under the control of the discharge controller 310, the water-ethanol phase 91b in the fuel tank 410 is discharged to the sub tank 420 by the pump 73 via the discharge port 411 and the discharge paths 62 and 63, that is, the discharge process is performed. Done. Subsequently, the phase separation determination device 51 determines whether or not the fuel 91 in the fuel tank 410 is phase-separated (in other words, whether or not the water-ethanol phase 91b remains in the fuel tank 410). (Step S13). If it is determined that the phases are separated (in other words, the water-ethanol phase 91b remains in the fuel tank 410) (step S13: YES), the discharge process is performed again (step S12). On the other hand, when it is determined that the phases are not separated (in other words, the water-ethanol phase 91b does not remain in the fuel tank 410) (step S13: NO), the discharge process is stopped (step S14: NO). That is, the pump 73 is controlled by the discharge control unit 310 so that the discharge of the water-ethanol phase 91b is stopped. Therefore, also in this case, there is no energy loss due to unnecessary discharge processing of the pump 73. In this way, the discharge process (step S12) is performed until the water-ethanol phase 91b in the fuel tank 410 is almost or preferably completely eliminated. Here, particularly in the present embodiment, the power source of the hybrid vehicle 1 is switched to the motor generator 200 during the period in which the discharge process for discharging the water-ethanol phase 91b from the fuel tank 410 to the sub tank 420 is performed. The EV traveling of the hybrid vehicle 1 is executed. Therefore, the engine 100 can be started using fuel with a high gasoline concentration by switching the power source to the engine 100 after the exhaust processing is completed (that is, starting the engine 100).

  Next, engine 100 is started using fuel 91 in fuel tank 410 (step S15). That is, the power switching unit 340 switches the power source of the hybrid vehicle 1 to the engine 100, and the fuel 91 in the fuel tank 410 is driven by the pump 71, the injector 120, and the like under the control of the fuel supply control unit 330. By being supplied to 100, the engine 100 is started. As described above, in this embodiment, in particular, the engine 100 can be started using the fuel 91 in the fuel tank 410 after the phase separation is eliminated (in other words, the gasoline phase 91a), that is, the fuel having a high gasoline concentration. . Therefore, for example, the startability of the engine 100 can be ensured or preferably improved at a low temperature or cold start.

  Next, after the engine 100 is warmed up, the fuel 92 (that is, the water-ethanol phase 91b) stored in the sub tank 420 is fractionated by the fractionator 600 (step S16). Specifically, first, the fuel 92 stored in the sub tank 420 is supplied by the pump 72 to the heat exchanger 610 via the fractionation passage 811. Next, heat exchange is performed between the fuel 92 and the engine coolant at about 80 ° C. by the heat exchanger 610. Thus, the fuel 92 has a gas phase composed of a component having a boiling point of less than about 80 ° C. and a liquid phase composed of a component having a boiling point of about 80 ° C. or more, with a distillation temperature of about 80 ° C., which is the engine coolant temperature. Is fractionated. Here, under atmospheric pressure, the boiling point of ethanol is about 78 ° C., and the boiling point of water is about 100 ° C. Thus, the gas phase will consist almost or completely of ethanol and the liquid phase will consist almost or completely of water. In other words, the gas phase is composed mainly of ethanol and contains little or no water. The gas phase generated by fractional distillation by the heat exchanger 610 is guided to the return passage 815 by the gas phase passage 812. On the other hand, the liquid phase is guided to a liquid phase tank (not shown) by the liquid phase passage 813 and stored in the liquid phase tank.

  Next, the gas phase guided from the gas phase passage 812 to the return passage 815 is returned to the fuel tank 410 by the return passage 815 (step S17). Therefore, the gas phase mainly composed of ethanol can be mixed with the fuel 91 in the fuel tank 410 (in other words, the gasoline phase 91a) and dissolved in the fuel 91. Here, since the gas phase mainly composed of ethanol contains little or no water, there is little or no possibility that phase separation will occur again by returning the gas phase to the fuel tank 410. Therefore, stable fuel supply from the fuel tank 410 to the engine 100 is possible.

  As described above, according to the control device 300 according to the present embodiment, the water-ethanol phase 91b generated by the phase separation is discharged from the fuel tank 410 by the pump 73, the discharge port 411, and the like. Phase separation can be eliminated. Furthermore, after the discharged water-ethanol phase 91b (that is, the fuel 92) is separated into a gas phase mainly composed of ethanol and a liquid phase mainly composed of water by the fractionator 600, ethanol is mainly composed. Only the gas phase is returned to the fuel tank by the return passage 815. Therefore, ethanol can be reliably dissolved again in the fuel in the fuel tank 410. Therefore, it is possible to supply fuel with stable properties to the engine 100. As a result, it is possible to reduce or prevent the combustion of the engine 100 from becoming unstable or the exhaust gas characteristics from deteriorating.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and the control of the internal combustion engine accompanying such a change. The apparatus is also included in the technical scope of the present invention.

It is a block diagram which shows the principal part of the control apparatus which concerns on 1st Embodiment, and the hybrid vehicle provided with this control apparatus. It is a schematic diagram for demonstrating phase separation. It is a flowchart which shows the operation processing of the control apparatus which concerns on 1st Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Hybrid vehicle, 51 ... Phase separation determination apparatus, 51a ... Alcohol sensor, 54 ... Engine speed sensor, 55 ... Oxygen sensor, 58 ... Temperature sensor, 62, 63 ... Discharge path, 71, 72, 73 ... Pump, 91 ... Fuel, 91a ... Gasoline phase, 91b ... Water-ethanol phase, 92 ... Fuel, 100 ... Engine, 120 ... Injector, 200 ... Motor generator, 300 ... Control device, 310 ... Discharge control unit, 320 ... Fraction control unit, 330 ... Fuel supply control unit, 340 ... Power switching unit, 410 ... Fuel tank, 411 ... Discharge port, 420 ... Sub tank, 510 ... Radiator, 511 ... Engine coolant flow path, 610 ... Heat exchanger, 711 ... Fuel path, 711a ... Fuel inlet

Claims (9)

A control device for an internal combustion engine that controls an internal combustion engine including a fuel tank that stores a mixed fuel in which gasoline and alcohol are mixed,
Discharge means for executing a discharge process for discharging the separated phase composed of the alcohol and water generated by the phase separation of the mixed fuel in the fuel tank from the fuel tank;
A fractionating means for performing fractional distillation for fractionating the discharged separated phase into a gas phase mainly composed of alcohol and a liquid phase mainly composed of water;
A control device for an internal combustion engine, comprising: return means for returning the gas phase from the fractionation means to the fuel tank.   The fractionating means heat-exchanges the cooling water for the internal combustion engine that cools the internal combustion engine and the discharged separated phase, thereby performing the fractionation process using the temperature of the cooling water for the internal combustion engine as a distillation temperature. The control device for an internal combustion engine according to claim 1, wherein the control device is executed.   The control apparatus for an internal combustion engine according to claim 2, further comprising a fractionation control means for controlling the fractionation means so as to execute the fractionation process after the internal combustion engine is started. Phase separation determining means for determining whether or not the separated phase is generated in the fuel tank;
And a discharge control means for controlling the discharge means so as to execute the discharge process when the phase separation determination means determines that the separated phase is generated. The control device for an internal combustion engine according to any one of claims 1 to 3. The internal combustion engine is provided in a hybrid vehicle together with a motor generator,
5. The apparatus further comprises power switching means for switching a power source for traveling of the hybrid vehicle from the internal combustion engine to the motor generator during at least the period during which the discharge process is performed. The control apparatus for an internal combustion engine according to any one of the above.   6. The control apparatus for an internal combustion engine according to claim 4, wherein the phase separation determination means includes water detection means for detecting whether or not water is contained in the fuel in the lower part of the fuel tank. .   The control apparatus for an internal combustion engine according to any one of claims 4 to 6, wherein the phase separation determination unit includes an alcohol concentration detection unit that detects an alcohol concentration of fuel in a lower portion of the fuel tank. .   The control device for an internal combustion engine according to any one of claims 1 to 7, wherein the discharge means is provided on a bottom surface of the fuel tank and has a discharge port for discharging the separated phase. Further comprising a separated phase storage tank for storing the separated phase;
The discharge means discharges the separated phase from the fuel tank to the separated phase storage tank as the discharge process,
The control of the internal combustion engine according to any one of claims 1 to 8, wherein the fractionation unit performs the fractionation process on a separated phase stored in the separated phase storage tank. apparatus.

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