JP4858422B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel supply control device for an internal combustion engine that can be operated by an alcohol mixed fuel in which alcohol is mixed with fuel.

  2. Description of the Related Art In recent years, so-called multi-fuel internal combustion engines have been adopted in which a plurality of types of fuels having different fuel properties are used in an internal combustion engine and the respective advantages are complemented and the advantages are mutually complemented. A vehicle equipped with this multi-fuel internal combustion engine is generally called a flexible fuel vehicle (FFV). One example is the use of gasoline fuel and alcohol fuel such as ethanol alone or in combination according to the required performance to improve the internal combustion engine emission performance and reduce consumption of fossil fuel such as gasoline fuel. Those that improve performance are known.

  In this case, the internal combustion engine has a merit when using gasoline fuel and a merit when using alcohol fuel, and it is desirable to use them according to the operating state of the internal combustion engine. For example, alcohol fuel has a larger latent heat of vaporization than gasoline fuel, and has a higher boiling point. Therefore, when the internal combustion engine is at a low temperature, it becomes difficult to evaporate and it is difficult to form a combustible mixture, which reduces the startability of the internal combustion engine. To do. On the other hand, since the alcohol fuel has a high octane number, it is possible to suppress the occurrence of knocking in a high rotation / high load region of the internal combustion engine.

  Therefore, a mixed fuel of alcohol fuel and gasoline fuel is stored in the main fuel tank, separated into gasoline fuel and alcohol fuel by the fuel separator, and the separated gasoline fuel and alcohol fuel are stored in the sub fuel tank, respectively. It is conceivable to selectively supply gasoline fuel or alcohol fuel to the internal combustion engine according to the operating state of the internal combustion engine. However, in this case, since a sub fuel tank for gasoline fuel and a sub fuel tank for alcohol fuel are required, the fuel mounting capacity to the vehicle increases.

  Therefore, when a mixed fuel of gasoline fuel and alcohol fuel is stored in the main fuel tank and the operation state of the internal combustion engine is suitable for using gasoline fuel, the fuel separator separates the fuel into gasoline fuel and alcohol fuel. Then, the separated gasoline fuel is stored in the sub fuel tank, and the gasoline fuel is supplied from the sub fuel tank to the internal combustion engine, while the alcohol fuel separated by the fuel separator is returned to the main fuel tank. Yes. For example, such an internal combustion engine is described in Patent Document 1 below.

JP 2006-132368 A

  However, as described above, the fuel separator separates the gasoline fuel and the alcohol fuel, stores the separated gasoline fuel in the sub fuel tank, and supplies the gasoline to the internal combustion engine. When the control to return to the main fuel tank is executed, only the gasoline fuel is consumed in the main fuel tank, and the alcohol concentration becomes high. Then, the fuel separator cannot separate the required amount of gasoline fuel, making it difficult to use the gasoline fuel and the alcohol fuel properly according to the operating state of the internal combustion engine, and the low temperature start performance is deteriorated.

  The present invention is intended to solve such problems, and provides a fuel supply control device for an internal combustion engine that improves performance by selectively using fuel having properties suitable for the operating state of the internal combustion engine. The purpose is to provide.

  In order to solve the above-described problems and achieve the object, a fuel supply control device for an internal combustion engine according to the present invention separates mixed fuel stored in a main fuel tank into alcohol fuel and hydrocarbon fuel by a fuel separator. An internal combustion engine capable of supplying one separated fuel to the sub fuel tank, returning the other fuel to the main fuel tank, and supplying the fuel stored in the main fuel tank or the sub fuel tank to the internal combustion engine In this fuel supply control device, after one fuel separated by the fuel separation device and stored in the sub fuel tank is supplied to the internal combustion engine, the other fuel separated by the fuel separation device is supplied to the sub fuel. It is stored in a tank and supplied to the internal combustion engine.

  In the fuel supply control apparatus for an internal combustion engine according to the present invention, when the operating state of the internal combustion engine enters a use area of one fuel, the fuel separation device separates the mixed fuel, and the separated fuel is used as the sub fuel. The fuel is stored in a tank, and supply of one fuel stored in the sub fuel tank to the internal combustion engine is started.

  In the internal combustion engine fuel supply control apparatus according to the present invention, when the operating state of the internal combustion engine deviates from one fuel use region, one fuel separated by the fuel separation device is returned to the main fuel tank, and the other The fuel is stored in the sub fuel tank, and the supply of the other fuel stored in the sub fuel tank to the internal combustion engine is started.

  In the fuel supply control device for an internal combustion engine of the present invention, when the supply amount of one fuel supplied to the internal combustion engine exceeds a predetermined amount set in advance, the one fuel separated by the fuel separation device is transferred to the main fuel. The fuel is returned to the tank, the other fuel is stored in the sub fuel tank, and the supply of the other fuel stored in the sub fuel tank to the internal combustion engine is started.

  In the fuel supply control device for an internal combustion engine of the present invention, when the difference between the supply amount of one fuel supplied to the internal combustion engine and the supply amount of the other fuel exceeds a predetermined amount set in advance, the fuel separation device One separated fuel is returned to the main fuel tank, the other fuel is stored in the sub fuel tank, and supply of the other fuel stored in the sub fuel tank to the internal combustion engine is started. It is said.

  In the fuel supply control apparatus for an internal combustion engine according to the present invention, when the alcohol concentration in the main fuel tank reaches a predetermined concentration, the supply of the other fuel to the internal combustion engine is terminated.

  In the fuel supply control apparatus for an internal combustion engine according to the present invention, when the alcohol concentration of the main fuel tank reaches a predetermined concentration set in advance and the other fuel stored in the sub fuel tank is exhausted, the main fuel tank The supply of the mixed fuel stored in the internal combustion engine to the internal combustion engine is started.

  According to the fuel supply control device for an internal combustion engine of the present invention, the mixed fuel stored in the main fuel tank is separated into the alcohol fuel and the hydrocarbon fuel, and one separated fuel is supplied to the sub fuel tank, The other fuel can be returned to the main fuel tank, and after one separated fuel is supplied to the internal combustion engine, the other separated fuel is forcibly supplied to the internal combustion engine, so that it is stored in the main fuel tank. The alcohol concentration of the mixed fuel will be maintained at a predetermined concentration, and fuel with properties suitable for the operating state of the internal combustion engine can be selectively used at all times, with low temperature starting performance and high rotation / high load. The performance can be improved.

  Embodiments of a fuel supply control device for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this Example.

  FIG. 1 is a schematic configuration diagram illustrating a fuel supply control device for an internal combustion engine according to a first embodiment of the present invention, and FIG. 2 is a flowchart illustrating mixed fuel separation and supply control by the fuel supply control device for the internal combustion engine according to the first embodiment. is there.

  The fuel supply control apparatus for an internal combustion engine according to the first embodiment uses a mixture of a plurality of types of fuels having different fuel properties, here, alcohol fuel and gasoline fuel (hydrocarbon fuel). As shown in FIG. 1, a cylinder head 12 is fastened on a cylinder block 11, and pistons 14 are fitted to a plurality of cylinder bores 13 formed on the cylinder block 11 so as to be movable up and down. A crankcase 15 is fastened to the lower part of the cylinder block 11, and a crankshaft 16 is rotatably supported in the crankcase 15. Each piston 14 is connected to the crankshaft 16 via a connecting rod 17. Has been.

  The combustion chamber 18 is constituted by the wall surface of the cylinder bore 13 in the cylinder block 11, the lower surface of the cylinder head 12, and the top surface of the piston 14, and the combustion chamber 18 has a high central portion at the upper portion (lower surface of the cylinder head 12). It has a pent roof shape that is slanted. An intake port 19 and an exhaust port 20 are formed on the upper portion of the combustion chamber 18, that is, the lower surface of the cylinder head 12, and the intake valve 19 and the exhaust valve 20 are opposed to the intake port 19 and the exhaust port 20. The lower end portions of 22 are respectively positioned. The intake valve 21 and the exhaust valve 22 are supported by the cylinder head 12 so as to be movable in the axial direction, and are urged and supported in a direction (upward in FIG. 1) for closing the intake port 19 and the exhaust port 20. ing. An intake cam shaft 23 and an exhaust cam shaft 24 are rotatably supported on the cylinder head 12, and the intake cam and the exhaust cam are in contact with upper ends of the intake valve 21 and the exhaust valve 22.

  Although not shown, the crankshaft sprocket fixed to the crankshaft 16 and the camshaft sprockets respectively fixed to the intake camshaft 23 and the exhaust camshaft 24 are wound with endless timing chains. The crankshaft 16, the intake camshaft 23, and the exhaust camshaft 24 can be interlocked.

  Accordingly, when the intake camshaft 23 and the exhaust camshaft 24 rotate in synchronization with the crankshaft 16, the intake cam and the exhaust cam move up and down the intake valve 21 and the exhaust valve 22 at a predetermined timing. The exhaust port 20 can be opened and closed to allow the intake port 19 and the combustion chamber 18 to communicate with the combustion chamber 18 and the exhaust port 20. In this case, the intake camshaft 23 and the exhaust camshaft 24 are set to rotate once (360 degrees) while the crankshaft 16 rotates twice (720 degrees). Therefore, the engine performs four strokes of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke while the crankshaft 16 rotates twice. At this time, the intake camshaft 23 and the exhaust camshaft 24 rotate once. Will be.

  The valve mechanism of the engine is a variable intake valve timing mechanism (VVT: Variable Valve Timing-intelligent) 25 that controls the intake valve 21 and the exhaust valve 22 at an optimal opening / closing timing according to the operating state. The intake variable valve mechanism 25 is configured by providing a VVT controller 26 at the shaft end of the intake camshaft 23, and the hydraulic pressure from the oil control valve 27 is supplied to an advance chamber and a retard chamber (not shown) of the VVT controller 26. By acting on this, the phase of the intake camshaft 23 with respect to the cam sprocket can be changed, and the opening / closing timing of the intake valve 21 can be advanced or retarded. In this case, the intake variable valve mechanism 25 advances or retards the opening / closing timing while keeping the operating angle (opening period) of the intake valve 21 constant. The intake camshaft 23 is provided with a cam position sensor 28 for detecting the rotational phase.

  A surge tank 30 is connected to the intake port 19 via an intake manifold 29, and an intake pipe 31 is connected to the surge tank 30. An air cleaner 32 is attached to an air intake port of the intake pipe 31. . An electronic throttle device 34 having a throttle valve 33 is provided on the downstream side of the air cleaner 32.

  An exhaust pipe 36 is connected to the exhaust port 20 via an exhaust manifold 35, and the exhaust pipe 36 has a three-way catalyst 37 for purifying harmful substances contained in the exhaust gas and a NOx occlusion reduction type catalyst 38. Is installed. This three-way catalyst 37 simultaneously purifies HC, CO, and NOx contained in the exhaust gas by an oxidation-reduction reaction when the air-fuel ratio (exhaust air-fuel ratio) is stoichiometric. The NOx occlusion reduction type catalyst 38 is in a rich combustion region or stoichiometric combustion region where the NOx contained in the exhaust gas is temporarily stored when the air-fuel ratio (exhaust air-fuel ratio) is lean, and the oxygen concentration in the exhaust gas is reduced. Sometimes, the stored NOx is released and NOx is reduced by the added fuel as a reducing agent.

  An exhaust gas recirculation passage (EGR passage) 39 is provided between the downstream side of the surge tank 23 in the intake pipe 31 and the upstream side of the three-way catalyst 37 in the exhaust pipe 36. Are provided with an EGR valve 40 and an EGR cooler 41. Further, an EGR gas temperature sensor 42 for detecting the temperature of the EGR gas is provided on the EGR passage 39 closer to the intake pipe 31 than the EGR valve 40.

  The cylinder head 12 is provided with an injector 43 that injects fuel into the intake port 19, and this injector 43 is attached to the intake manifold 29 of the cylinder head 12, and is inclined downward by a predetermined angle from the horizontal upper end. ing. The injectors 43 attached to the respective cylinders are connected to a delivery pipe 44, and a fuel supply system (to be described later) is connected to the delivery pipe 44 through a fuel supply pipe 45. The cylinder head 12 is equipped with a spark plug 46 that is located above the combustion chamber 18 and ignites the air-fuel mixture.

  In the fuel supply system described above, the main fuel tank 47 stores a mixed fuel obtained by mixing gasoline fuel and alcohol fuel at a predetermined ratio. A feed pump 48 is disposed in the main fuel tank 47, and a main fuel supply pipe 50 is connected to the feed pump 48 through a filter 49. The sub fuel tank 51 can store the separated gasoline fuel or alcohol fuel. A feed pump 52 is disposed in the sub fuel tank 51, and a sub fuel supply pipe 53 is connected to the feed pump 52. The end portions of the fuel supply pipe 45, the main fuel supply pipe 50, and the sub fuel supply pipe 53 are connected by a three-way supply fuel switching valve 54.

  Accordingly, the feed pump 48 pressurizes the mixed fuel in the main fuel tank 47 to a predetermined low pressure and supplies it to the main fuel supply pipe 50, and the feed pump 52 supplies the alcohol fuel or gasoline fuel in the sub fuel tank 51 as the sub fuel. The tube 53 can be supplied. When the fuel supply pipe 45 and the main fuel supply pipe 50 are communicated by the supply fuel switching valve 54, the mixed fuel in the main fuel tank 47 is supplied from the main fuel supply pipe 50 to the delivery pipe 44 through the fuel supply pipe 45. The injector 43 can inject the mixed fuel in the delivery pipe 44 into the intake port 19. On the other hand, when the fuel supply pipe 45 and the sub fuel supply pipe 53 are communicated by the supply fuel switching valve 54, the alcohol fuel or gasoline fuel in the sub fuel tank 51 is transferred from the sub fuel supply pipe 53 to the delivery pipe 44 through the fuel supply pipe 45. The injector 43 can inject gasoline fuel or alcohol fuel in the delivery pipe 44 into the intake port 19.

  The fuel separation device 55 separates the mixed fuel into gasoline fuel and alcohol fuel using a separation membrane (not shown) when necessary, and is constituted by a known technique. That is, the fuel branch pipe 56 branched from the main fuel supply pipe 50 is connected to the fuel separator 55 at the tip, and a shutoff valve 57 is mounted in the middle. A three-type first separation fuel switching valve 59 is connected to the tip of the first fuel separation pipe 58 extended from the fuel separation device 55, and a first branch branched from the first separation fuel switching valve 59. The tip of the first separated fuel supply pipe 60 is connected to the sub fuel tank 51, while the tip of the first separated fuel return pipe 61 branched from the first separated fuel switching valve 59 is connected to the main fuel tank 47. . A three-type second separated fuel switching valve 63 is connected to the tip of the second fuel separation pipe 62 extended from the fuel separation device 55, and the second branched from the second separated fuel switching valve 63. The tip of the separated fuel supply pipe 64 is connected to the sub fuel tank 51, while the tip of the second separated fuel return pipe 65 branched from the second separated fuel switching valve 63 is connected to the main fuel tank 47.

  Accordingly, when the fuel separator 55 is operated and the shutoff valve 57 is opened, the mixed fuel in the main fuel tank 47 is introduced from the main fuel supply pipe 50 through the fuel branch pipe 56 to the fuel separator 55, where the fuel separator 55 is separated. The mixed fuel can be separated into gasoline fuel and alcohol fuel by the membrane. The separated gasoline fuel is discharged to the first fuel separation pipe 58 and supplied to the sub fuel tank 51 through the first separated fuel supply pipe 60 by the switching operation of the first separated fuel switching valve 59, or the first It can be returned to the main fuel tank 47 through the separated fuel return pipe 61. On the other hand, the separated alcohol fuel is discharged to the second fuel separation pipe 62 and supplied to the sub fuel tank 51 through the second separated fuel supply pipe 64 by the switching operation of the second separated fuel switching valve 63 or the second fuel separation pipe 62. The fuel can be returned to the main fuel tank 47 through the separated fuel return pipe 65.

  The vehicle is equipped with an electronic control unit (ECU) 66, which can control the fuel injection timing of the injector 43, the ignition timing of the spark plug 46, and the like. The fuel injection amount, injection timing, ignition timing, and the like are determined based on engine operating conditions such as temperature, throttle opening, accelerator opening, engine speed, and coolant temperature.

  That is, an airflow sensor 67 and an intake air temperature sensor 68 are mounted on the upstream side of the intake pipe 31, and the measured intake air amount and intake air temperature are output to the ECU 66. The electronic throttle device 34 is provided with a throttle position sensor 69, and the accelerator pedal is provided with an accelerator position sensor 70, which outputs the current throttle opening and accelerator opening to the ECU 66. The crankshaft 16 is provided with a crank angle sensor 71 and outputs the detected crank angle to the ECU 66. The ECU 66 discriminates the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke in each cylinder based on the crank angle, and the engine. Calculate the number of revolutions. Further, the cylinder block 11 is provided with a water temperature sensor 72 and outputs the detected engine cooling water temperature to the ECU 66.

  An air-fuel ratio (A / F) sensor (or oxygen sensor) 73 is provided upstream of the three-way catalyst 37 in the exhaust pipe 36. The A / F sensor 73 detects the exhaust air / fuel ratio (oxygen amount) of the exhaust gas exhausted from the combustion chamber 18 through the exhaust port 20 and the exhaust manifold 35 to the exhaust pipe 36, and outputs the detected exhaust air / fuel ratio to the ECU 66. is doing. The ECU 66 corrects the fuel injection amount by feeding back the exhaust air-fuel ratio detected by the A / F sensor 61 and comparing it with the target air-fuel ratio set according to the engine operating state.

  The main fuel tank 47 stores a mixed fuel of alcohol fuel and gasoline fuel, and is provided with a remaining amount sensor 74 for detecting the remaining amount of the stored mixed fuel. Is output to the ECU 66. Further, the main fuel tank 47 is provided with a concentration temperature sensor 75 for detecting the alcohol concentration in the mixed fuel stored in the main fuel tank 47, and outputs the detected alcohol concentration in the mixed fuel to the ECU 66. Yes. On the other hand, the sub fuel tank 51 is capable of storing alcohol fuel or gasoline fuel separated from the mixed fuel, and is provided with a remaining amount sensor 76 for detecting the remaining amount of the stored alcohol fuel or gasoline fuel. The detected remaining fuel amount is output to the ECU 66.

  The ECU 66 can control the intake variable valve mechanism 25 based on the engine operating state. That is, when the temperature is low, the engine is started, the engine is idle, or the load is light, the exhaust gas blows back into the intake port 19 or the combustion chamber 18 by eliminating the overlap between the exhaust valve 22 closing timing and the intake valve 21 opening timing. Reduce the amount to enable stable combustion and improved fuel efficiency. Further, at the time of medium load, by increasing the overlap, the internal EGR rate is increased to improve the exhaust gas purification efficiency, and the pumping loss is reduced to improve the fuel consumption. Further, at the time of high-load low-medium rotation, the closing timing of the intake valve 21 is advanced, thereby reducing the amount of intake air that blows back to the intake port 19 and improving the volume efficiency. At the time of high load and high rotation, the closing timing of the intake valve 21 is retarded in accordance with the rotation speed, so that the timing is adjusted to the inertial force of the intake air and the volume efficiency is improved.

  Further, the ECU 66 can switch the fuel supply system based on the engine operating state, and can selectively supply gasoline fuel, alcohol fuel, and mixed fuel to the engine. That is, the ECU 66 can control the supply fuel switching valve 54, the shut-off valve 57, the first separated fuel switching valve 59, and the second separated fuel switching valve 63 based on the engine operating state, and operates the fuel separation device 55. Control is possible.

  Further, an ignition key switch 77 is provided at the driver's seat of the vehicle, and the ON / OFF state thereof is output to the ECU 66.

  By the way, as described above, the internal combustion engine of the first embodiment can use a mixed fuel obtained by mixing gasoline fuel and alcohol fuel such as ethanol at a predetermined ratio, and separate this mixed fuel to use gasoline fuel alone. In addition, alcohol fuel can be used alone. In other words, alcohol fuel has a larger latent heat of vaporization and higher boiling point than gasoline fuel, so that it is difficult to evaporate at a low temperature of the internal combustion engine, it is difficult to form a combustible mixture, and the startability of the internal combustion engine is reduced. On the other hand, since the octane number is high, the occurrence of knocking can be suppressed in the high rotation / high load region of the internal combustion engine.

  Therefore, the ECU 66 controls the fuel supply switching valve 54, the shut-off valve 57, the first separated fuel switching valve 59, the second separated fuel switching valve 63, and the fuel separation device 55, so that when the internal combustion engine is cold started, the fuel The gasoline fuel separated by the separation device 55 is stored in the sub fuel tank 51, and gasoline fuel is supplied from the sub fuel tank 51 to the internal combustion engine, while alcohol fuel is returned to the main fuel tank 47. Further, when the internal combustion engine is at high speed and high load, the alcohol fuel separated by the fuel separation device 55 is stored in the sub fuel tank 51, and the alcohol fuel is supplied from the sub fuel tank 51 to the internal combustion engine, while gasoline fuel is supplied. It is returned to the main fuel tank 47. When the internal combustion engine other than that is operated, the mixed fuel is supplied to the internal combustion engine.

  However, the fuel separator 55 separates the gasoline fuel and the alcohol fuel. The separated gasoline fuel is stored in the sub fuel tank 51 and supplied to the internal combustion engine, while the separated alcohol fuel is returned to the main fuel tank 47. In the main fuel tank 47, consumption of gasoline fuel increases and the alcohol concentration increases. On the other hand, when the separated alcohol fuel is supplied to the internal combustion engine and the separated gasoline fuel is returned to the main fuel tank 47, consumption of the alcohol fuel increases in the main fuel tank 47 and the alcohol concentration becomes low.

  Therefore, in the fuel supply control device for the internal combustion engine of the first embodiment, the ECU 66 supplies one fuel (gasoline fuel or alcohol fuel) separated by the fuel separation device 55 and stored in the sub fuel tank 51 to the internal combustion engine. After that, the other fuel separated by the fuel separation device 55 is stored in the sub fuel tank 51 and supplied to the internal combustion engine.

  At this time, when the operating state of the internal combustion engine enters the one fuel use region, the ECU 66 separates the mixed fuel into gasoline fuel and alcohol fuel by the fuel separator 55 and puts the separated fuel into the sub fuel tank 51. The supply of one fuel stored in the sub fuel tank 51 to the internal combustion engine is started. On the other hand, the ECU 66 returns one fuel separated by the fuel separator 55 to the main fuel tank 47 and stores the other fuel in the sub fuel tank 51 when the operating state of the internal combustion engine deviates from one fuel use region. Then, the supply of the other fuel stored in the sub fuel tank 51 to the internal combustion engine is started.

  In this case, the ECU 66 ends the supply of the other fuel to the internal combustion engine when the alcohol concentration in the main fuel tank 47 reaches a predetermined concentration set in advance and the other fuel stored in the sub fuel tank 51 runs out. Then, the supply of the mixed fuel stored in the main fuel tank 47 to the internal combustion engine is started.

  Here, the mixed fuel separation and supply control by the fuel supply control device of the internal combustion engine of the first embodiment will be described based on the flowchart of FIG.

  In the mixed fuel separation and supply control by the fuel supply control device for the internal combustion engine of the first embodiment, as shown in FIG. 2, when the ignition key switch (IG-ON) 77 is turned on in step S10, in step S11. The ECU 66 reads the alcohol concentration L in the mixed fuel stored in the main fuel tank 47 detected by the concentration sensor 75. In step S12, the ECU 66 determines whether an essential condition for using gasoline fuel is satisfied based on the operating state of the internal combustion engine. That is, it is determined whether the engine cooling water temperature detected by the water temperature sensor 72 is lower than a predetermined cooling water temperature set in advance and the internal combustion engine is cold-started.

  Here, if it is determined that the indispensable condition for using gasoline fuel is not satisfied, the process proceeds to step S25, where fuel injection is performed with alcohol-mixed fuel. That is, as shown in FIG. 1, the ECU 66 connects the fuel supply pipe 45 and the main fuel supply pipe 50 by the supply fuel switching valve 54 with the shutoff valve 57 closed and the fuel separation device 55 stopped. Then, the mixed fuel in the main fuel tank 47 is supplied from the main fuel supply pipe 50 to the delivery pipe 44 through the fuel supply pipe 45, and the injector 43 injects the mixed fuel into the intake port 19.

  On the other hand, returning to FIG. 2, if it is determined in step S12 that the essential condition for using gasoline fuel is satisfied, the fuel separator 55 is activated (ON) in step S13, and in step S14. The gasoline fuel separated by the fuel separator 55 is stored in the sub fuel tank 51, and is switched to the sub fuel tank 51 in step S15, and fuel injection is performed with the gasoline fuel.

  That is, as shown in FIG. 1, the ECU 66 operates the fuel separation device 55 and opens the shut-off valve 57, and the first fuel separation pipe 58 and the first separated fuel supply pipe by the first separated fuel switching valve 59. 60, and the second fuel separation pipe 62 and the second separated fuel return pipe 65 are communicated by the second separated fuel switching valve 63. In this state, the fuel supply pipe 45 and the sub fuel supply are fed by the supply fuel switching valve 54. The pipe 53 is communicated. Then, the mixed fuel in the main fuel tank 47 is introduced from the main fuel supply pipe 50 through the fuel branch pipe 56 to the fuel separator 55, where the mixed fuel is separated into gasoline fuel and alcohol fuel. The separated gasoline fuel is stored in the sub fuel tank 51 from the first fuel separation pipe 58 through the first separated fuel supply pipe 60, while the separated alcohol fuel is stored in the second separated fuel from the second fuel separation pipe 62. It is returned to the main fuel tank 47 through the return pipe 65. Then, the gasoline fuel in the sub fuel tank 51 is supplied from the sub fuel supply pipe 53 to the delivery pipe 44 through the fuel supply pipe 45, and the injector 43 injects the gasoline fuel into the intake port 19.

  Returning to FIG. 2, in step S <b> 16, the ECU 66 determines whether or not the essential condition for using gasoline fuel has ended based on the operating state of the internal combustion engine. That is, it is determined whether the engine coolant temperature detected by the water temperature sensor 72 is higher than a predetermined coolant temperature set in advance and the internal combustion engine has been completely warmed up. Here, if it is determined that the essential condition for using gasoline fuel has not ended, the process returns to step S14 and the process is repeated. On the other hand, if it is determined in step S16 that the essential condition for using gasoline fuel has ended, the process proceeds to step S17.

  In step S17, the ECU 66 switches the flow path between the gasoline fuel and the alcohol fuel separated by the fuel separation device 55, and in step S18, in the mixed fuel stored in the main fuel tank 47 detected by the concentration sensor 75. The alcohol concentration AL is read, the alcohol fuel separated by the fuel separator 55 is stored in the sub fuel tank 51 in step S19, and fuel injection is performed with the alcohol fuel in step S20.

  That is, as shown in FIG. 1, the ECU 66 communicates the first fuel separation pipe 58 and the first separated fuel return pipe 61 by the first separated fuel switching valve 59, and the second fuel by the second separated fuel switching valve 63. The separation pipe 62 and the second separated fuel supply pipe 64 are communicated. Then, the mixed fuel in the main fuel tank 47 is introduced from the main fuel supply pipe 50 through the fuel branch pipe 56 to the fuel separator 55, where the mixed fuel is separated into gasoline fuel and alcohol fuel. The separated gasoline fuel is returned from the first fuel separation pipe 58 to the main fuel tank 47 through the first separated fuel return pipe 61, while the separated alcohol fuel is supplied from the second fuel separation pipe 62 to the second separated fuel supply. The sub fuel tank 51 is supplied through the pipe 64. Then, the alcohol fuel in the sub fuel tank 51 is supplied from the sub fuel supply pipe 53 to the delivery pipe 44 through the fuel supply pipe 45, and the injector 43 injects the alcohol fuel into the intake port 19.

  Returning to FIG. 2, in step S21, the ECU 66 determines whether the alcohol concentration AL in the mixed fuel stored in the main fuel tank 47 has become a concentration approximate to the alcohol concentration L in the mixed fuel before the start of control. Determine. In this case, a predetermined concentration range is set for the alcohol concentration L in the mixed fuel before the start of control, and the alcohol concentration AL in the main fuel tank 47 falls within the concentration range corresponding to the alcohol concentration L before the start of control. Determine whether or not.

  If it is determined in step S21 that the alcohol concentration AL in the mixed fuel in the main fuel tank 47 is not close to the alcohol concentration L in the mixed fuel before the start of control, the process returns to step S18 and the processing is repeated. . On the other hand, if it is determined here that the alcohol concentration AL in the mixed fuel in the main fuel tank 47 is close to the alcohol concentration L in the mixed fuel before the start of control, the operation of the fuel separator 55 is activated in step S22. In step S23, the ECU 66 determines whether or not the remaining amount of alcohol fuel in the sub fuel tank 51 detected by the remaining amount sensor 76 has become zero.

  In this step S23, fuel injection by alcohol fuel is continued until the remaining amount of alcohol fuel in the sub fuel tank 51 becomes zero, and if it is determined that the remaining amount of alcohol fuel in the sub fuel tank 51 has become zero, step S23 is performed. In S24, the main fuel tank 47 is switched to, and in step S25, fuel injection is performed with alcohol-mixed fuel.

  That is, as shown in FIG. 1, the ECU 66 closes the shut-off valve 57 and connects the fuel supply pipe 45 and the main fuel supply pipe 50 by the supply fuel switching valve 54. Then, the mixed fuel in the main fuel tank 47 is supplied from the main fuel supply pipe 50 to the delivery pipe 44 through the fuel supply pipe 45, and the injector 43 injects the alcohol mixed fuel into the intake port 19.

  As described above, in the fuel supply control device for the internal combustion engine of the first embodiment, the mixed fuel stored in the main fuel tank 47 is separated into the alcohol fuel and the hydrocarbon fuel by the fuel separation device 55 and separated. The fuel is supplied to the sub fuel tank 51 and the other fuel is returned to the main fuel tank 47 so that the fuel stored in the main fuel tank 47 or the sub fuel tank 51 can be supplied to the internal combustion engine. One fuel separated by 55 and stored in the sub fuel tank 51 is supplied to the internal combustion engine, and then the other fuel separated by the fuel separator 55 is stored in the sub fuel tank 51 and supplied to the internal combustion engine. I have to.

  Therefore, for example, when an operating condition for supplying gasoline fuel is established in the internal combustion engine, the gasoline fuel separated by the fuel separator 55 is stored in the sub fuel tank 47 and supplied to the internal combustion engine, and then the internal combustion engine. When the operating condition for supplying gasoline fuel is released, the alcohol fuel separated by the fuel separator 55 is stored in the sub fuel tank 51 and supplied to the internal combustion engine. Therefore, the alcohol concentration of the mixed fuel stored in the main fuel tank 47 is maintained at a predetermined concentration, and a fuel having a property suitable for the operating state of the internal combustion engine, that is, gasoline fuel or alcohol fuel is selectively selected at all times. It can be used, and it is possible to improve the cold start performance and performance at high rotation and high load.

  In the fuel supply control device for an internal combustion engine according to the first embodiment, when the operating state of the internal combustion engine enters the use range of one fuel, the fuel separation device 55 separates the mixed fuel, and the separated fuel is sub- While the fuel is stored in the fuel tank 51 and the supply to the internal combustion engine is started, when the operating state of the internal combustion engine deviates from the one fuel use region, one fuel separated by the fuel separation device 55 is stored in the main fuel tank 47. The other fuel is stored in the sub fuel tank 51, and the supply to the internal combustion engine is started. Therefore, either the gasoline fuel or the alcohol fuel suitable for the operating state of the internal combustion engine is appropriately supplied to the internal combustion engine, and then the other fuel is supplied, so that the alcohol concentration of the mixed fuel in the main fuel tank 47 is set to a predetermined concentration. Can be maintained.

  In the fuel supply control device for the internal combustion engine of the first embodiment, when the alcohol concentration in the main fuel tank 47 reaches a predetermined concentration, the operation of the fuel separation device 55 is stopped and stored in the sub fuel tank 51. When the other fuel is exhausted, the supply of the mixed fuel stored in the main fuel tank 47 to the internal combustion engine is started. Therefore, when the mixed fuel stored in the main fuel tank 47 is supplied to the internal combustion engine, the fuel separation device 55 is operated to separate the fuel by maintaining the sub fuel tank 51 in an empty state. The gasoline fuel or alcohol fuel separated in the sub fuel tank 51 can be stored appropriately, and fuel injection can be executed with high accuracy.

  FIG. 3 is a flowchart showing mixed fuel separation and supply control by the fuel supply control apparatus for an internal combustion engine according to the second embodiment of the present invention. The overall configuration of the internal combustion engine fuel supply control apparatus according to the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and has the same functions as those described in this embodiment. The members having the same reference numerals are denoted by the same reference numerals and redundant description is omitted.

  In the fuel supply control device for an internal combustion engine according to the second embodiment, when the supply amount of one fuel supplied to the internal combustion engine exceeds a predetermined amount set in advance, one separated fuel is returned to the main fuel tank, The fuel is stored in the sub fuel tank, and the supply of the other fuel stored in the sub fuel tank to the internal combustion engine is started.

  Here, the mixed fuel separation and supply control by the fuel supply control device for the internal combustion engine of the second embodiment will be described based on the schematic diagram of FIG. 1 and the flowchart of FIG.

  In the mixed fuel separation and supply control by the fuel supply control device of the internal combustion engine of the second embodiment, as shown in FIGS. 1 and 3, when the ignition key switch (IG-ON) 77 is turned on in step S30, a step is performed. In S31, the ECU 66 reads the alcohol concentration L in the mixed fuel stored in the main fuel tank 47 detected by the concentration sensor 75. In step S32, the ECU 66 satisfies the condition that it is better to use gasoline fuel than the mixed fuel in which the alcohol fuel having the alcohol concentration L is mixed with the gasoline fuel, based on the operating state of the internal combustion engine. Determine if you did. For example, it is determined whether the engine cooling water temperature detected by the water temperature sensor 72 is lower than a predetermined cooling water temperature set in advance and the internal combustion engine is operating at a low temperature.

  Here, if it is determined that the condition that it is better to use gasoline fuel is not satisfied, the process proceeds to step S46, where fuel injection is performed with the alcohol-mixed fuel. That is, the ECU 66 closes the shut-off valve 57, stops the fuel separation device 55, and connects the fuel supply pipe 45 and the main fuel supply pipe 50 with the supply fuel switching valve 54. Then, the mixed fuel in the main fuel tank 47 is supplied from the main fuel supply pipe 50 to the delivery pipe 44 through the fuel supply pipe 45, and the injector 43 injects the mixed fuel into the intake port 19.

  On the other hand, if it is determined in step S32 that the condition for using gasoline fuel is better, the fuel separation device 55 is activated (ON) in step S33, and the fuel in step S34. The gasoline fuel separated by the separation device 55 is stored in the sub fuel tank 51, and is switched to the sub fuel tank 51 in step S35 to execute fuel injection with the gasoline fuel.

  That is, the ECU 66 operates the fuel separation device 55, opens the shut-off valve 57, communicates the first fuel separation pipe 58 and the first separated fuel supply pipe 60 with the first separated fuel switching valve 59, and the second separated fuel. The second fuel separation pipe 62 and the second separated fuel return pipe 65 are communicated by the switching valve 63, and the fuel supply pipe 45 and the sub fuel supply pipe 53 are communicated by the supply fuel switching valve 54. Then, the mixed fuel in the main fuel tank 47 is introduced into the fuel separator 55 from the main fuel supply pipe 50 through the fuel branch pipe 56, the mixed fuel is separated into gasoline fuel and alcohol fuel, and the separated gasoline fuel is The alcohol fuel separated from the first fuel separation pipe 58 through the first separated fuel supply pipe 60 is stored in the sub fuel tank 51, while the separated alcohol fuel is supplied from the second fuel separation pipe 62 through the second separated fuel return pipe 65 to the main fuel. Returned to tank 47. Then, the gasoline fuel in the sub fuel tank 51 is supplied from the sub fuel supply pipe 53 to the delivery pipe 44 through the fuel supply pipe 45, and the injector 43 injects the gasoline fuel into the intake port 19.

  Then, in step S36, the ECU 66 determines whether or not the condition that it is better to use gasoline fuel has ended based on the operating state of the internal combustion engine. Here, if it is determined that the conditions for using gasoline fuel are better, the supply amount of gasoline fuel supplied to the internal combustion engine becomes equal to or greater than a predetermined amount A set in advance in step S37. Determine whether or not. In this case, the predetermined amount A is an amount that makes it difficult to restore the alcohol concentration in the mixed fuel in the main fuel tank 47 if the gasoline fuel is continuously supplied. The supply amount of gasoline fuel supplied to the internal combustion engine is calculated based on the fuel injection amount, the engine speed, the control duration, and the like. If it is determined that the supply amount of gasoline fuel is not equal to or greater than the predetermined amount A, the process returns to step S34 and the process is repeated. On the other hand, if it is determined in step S36 that the conditions for using gasoline fuel are better, or if it is determined in step S37 that the supply amount of gasoline fuel is equal to or greater than the predetermined amount A, step S38 is performed. Migrate to

  In step S38, the ECU 66 switches the flow path between the gasoline fuel and the alcohol fuel separated by the fuel separation device 55, and in step S39, in the mixed fuel stored in the main fuel tank 47 detected by the concentration sensor 75. The alcohol concentration AL is read, the alcohol fuel separated by the fuel separator 55 is stored in the sub fuel tank 51 in step S40, and fuel injection is performed with the alcohol fuel in step S41.

  That is, the ECU 66 communicates the first fuel separation pipe 58 and the first separated fuel return pipe 61 by the first separated fuel switching valve 59, and the second fuel separation pipe 62 and the second separated fuel by the second separated fuel switching valve 63. The supply pipe 64 is communicated. Then, the mixed fuel in the main fuel tank 47 is introduced from the main fuel supply pipe 50 through the fuel branch pipe 56 to the fuel separator 55, where the mixed fuel is separated into gasoline fuel and alcohol fuel and separated. The gasoline fuel is returned from the first fuel separation pipe 58 to the main fuel tank 47 through the first separated fuel return pipe 61, while the separated alcohol fuel is fed from the second fuel separation pipe 62 through the second separated fuel supply pipe 64. It is supplied to the sub fuel tank 51. Then, the alcohol fuel in the sub fuel tank 51 is supplied from the sub fuel supply pipe 53 to the delivery pipe 44 through the fuel supply pipe 45, and the injector 43 injects the alcohol fuel into the intake port 19.

  In step S42, the ECU 66 determines whether or not the alcohol concentration AL in the mixed fuel stored in the main fuel tank 47 is close to the alcohol concentration L in the mixed fuel before the start of control. Here, if it is determined that the alcohol concentration AL in the mixed fuel in the main fuel tank 47 is not close to the alcohol concentration L in the mixed fuel before the start of control, the process returns to step S39 and the process is repeated. On the other hand, if it is determined that the alcohol concentration AL in the mixed fuel in the main fuel tank 47 is close to the alcohol concentration L in the mixed fuel before the start of control, the operation of the fuel separator 55 is stopped in step S43 ( In step S44, the ECU 66 determines whether or not the remaining amount of alcohol fuel in the sub fuel tank 51 detected by the remaining amount sensor 76 has become zero.

  In this step S44, fuel injection by alcohol fuel is continued until the remaining amount of alcohol fuel in the sub fuel tank 51 becomes zero, and if it is determined that the remaining amount of alcohol fuel in the sub fuel tank 51 has become zero, step S44 is performed. In S45, the main fuel tank 47 is switched to, and in step S46, fuel injection is performed with the alcohol-mixed fuel.

  That is, the ECU 66 closes the shut-off valve 57 and causes the fuel supply pipe 45 and the main fuel supply pipe 50 to communicate with each other through the fuel supply switching valve 54. Then, the mixed fuel in the main fuel tank 47 is supplied from the main fuel supply pipe 50 to the delivery pipe 44 through the fuel supply pipe 45, and the injector 43 injects the alcohol mixed fuel into the intake port 19.

  As described above, in the fuel supply control apparatus for an internal combustion engine according to the second embodiment, one fuel separated by the fuel separator 55 and stored in the sub fuel tank 47 is supplied to the internal combustion engine, and then supplied to the internal combustion engine. When the amount of gasoline fuel to be supplied exceeds a predetermined amount A set in advance, the other fuel separated by the fuel separator 55 is stored in the sub fuel tank 51 and supplied to the internal combustion engine.

  Therefore, for example, when an operating condition in which it is better to supply gasoline fuel in an internal combustion engine is satisfied, the gasoline fuel separated by the fuel separator 55 is stored in the sub fuel tank 47 and supplied to the internal combustion engine. Thereafter, when the operating condition in which it is better to supply gasoline fuel to the internal combustion engine is canceled or when the supply amount of gasoline fuel becomes a predetermined amount A or more, the alcohol fuel separated by the fuel separation device 55 is sublimated. It is stored in the fuel tank 51 and supplied to the internal combustion engine. Therefore, the alcohol concentration of the mixed fuel stored in the main fuel tank 47 is maintained at a predetermined concentration, and a fuel having a property suitable for the operating state of the internal combustion engine, that is, gasoline fuel or alcohol fuel is selectively selected at all times. It can be used, and it is possible to improve the cold start performance and performance at high rotation and high load.

  Further, when the supply amount of the gasoline fuel becomes equal to or greater than the predetermined amount A, the supply of the gasoline fuel to the internal combustion engine is stopped and the supply of the alcohol fuel is started. Can be restored to the alcohol concentration L before the start of control at an early stage, and highly accurate fuel supply control can be realized.

  FIG. 4 is a flowchart showing mixed fuel separation and supply control by the fuel supply control apparatus for an internal combustion engine according to the third embodiment of the present invention. The overall configuration of the internal combustion engine fuel supply control apparatus according to the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and has the same functions as those described in this embodiment. The members having the same reference numerals are denoted by the same reference numerals and redundant description is omitted.

  In the fuel supply control device for an internal combustion engine according to the third embodiment, when the difference between the supply amount of one fuel supplied to the internal combustion engine and the supply amount of the other fuel exceeds a predetermined amount set in advance, The fuel is returned to the main fuel tank, the other fuel is stored in the sub fuel tank, and the supply of the other fuel stored in the sub fuel tank to the internal combustion engine is started.

  Here, the mixed fuel separation and supply control by the fuel supply control device for the internal combustion engine of the third embodiment will be described based on the schematic diagram of FIG. 1 and the flowchart of FIG.

  In the mixed fuel separation and supply control by the fuel supply control device of the internal combustion engine of the third embodiment, as shown in FIGS. 1 and 4, when the ignition key switch (IG-ON) 77 is turned on in step S50, a step is performed. In S51, the ECU 66 reads the alcohol concentration L in the mixed fuel stored in the main fuel tank 47 detected by the concentration sensor 75. In step S52, the ECU 66 satisfies the condition that it is better to use the gasoline fuel than the mixed fuel in which the alcohol fuel having the alcohol concentration L is mixed with the gasoline fuel based on the operation state of the internal combustion engine. Determine if you did.

  Here, if it is determined that the condition that it is better to use gasoline fuel is not satisfied, the process proceeds to step S66, where fuel injection is performed with alcohol-mixed fuel. On the other hand, if it is determined in step S52 that the condition for using gasoline fuel is better, the fuel separator 55 is operated (ON) in step S53, and the fuel is determined in step S54. The gasoline fuel separated by the separator 55 is stored in the sub fuel tank 51, and is switched to the sub fuel tank 51 in step S55, and fuel injection is performed with the gasoline fuel.

  In step S56, the ECU 66 determines whether or not the condition that it is better to use gasoline fuel has ended based on the operating state of the internal combustion engine. Here, if it is determined that the condition for using gasoline fuel is better, the difference between the supply amount of gasoline fuel supplied to the internal combustion engine and the supply amount of alcohol fuel is determined in advance in step S57. It is determined whether or not the set predetermined amount is exceeded. Specifically, a predetermined amount in which a value obtained by subtracting the supply amount B of gasoline fuel supplied to the internal combustion engine from the remaining amount Q of the mixed fuel stored in the main fuel tank 47 detected by the remaining amount sensor 74 is set. It is determined whether or not C is exceeded. In this case, the predetermined amount C is an amount that makes it difficult to restore the alcohol concentration in the mixed fuel in the main fuel tank 47 if the gasoline fuel is continuously supplied. If it is determined that the value obtained by subtracting the gasoline fuel supply amount B from the remaining fuel amount Q in the main fuel tank 47 does not exceed the predetermined amount C, the process returns to step S54 and the process is repeated. On the other hand, in step S56, it is determined that the condition for using gasoline fuel is better, or in step S57, the gasoline fuel supply amount B is subtracted from the remaining amount Q of the main fuel tank 47. If it is determined that the value exceeds the predetermined amount C, the process proceeds to step S58.

  In step S58, the ECU 66 switches the flow path between the gasoline fuel and the alcohol fuel separated by the fuel separation device 55, and in step S59, in the mixed fuel stored in the main fuel tank 47 detected by the concentration sensor 75. The alcohol concentration AL is read, the alcohol fuel separated by the fuel separator 55 is stored in the sub fuel tank 51 in step S60, and fuel injection is performed with the alcohol fuel in step S61.

  In step S62, the ECU 66 determines whether or not the alcohol concentration AL in the mixed fuel stored in the main fuel tank 47 has become a concentration approximate to the alcohol concentration L in the mixed fuel before the start of control. Here, if it is determined that the alcohol concentration AL in the mixed fuel in the main fuel tank 47 is not close to the alcohol concentration L in the mixed fuel before the start of control, the process returns to step S59 and the process is repeated. On the other hand, if it is determined that the alcohol concentration AL in the mixed fuel in the main fuel tank 47 is close to the alcohol concentration L in the mixed fuel before the start of control, the operation of the fuel separator 55 is stopped in step S63 ( In step S64, the ECU 66 determines whether or not the remaining amount of alcohol fuel in the sub fuel tank 51 detected by the remaining amount sensor 76 has become zero.

  In this step S64, fuel injection by alcohol fuel is continued until the remaining amount of alcohol fuel in the sub fuel tank 51 becomes zero, and if it is determined that the remaining amount of alcohol fuel in the sub fuel tank 51 has become zero, step S64 is performed. In step S65, the main fuel tank 47 is switched to, and in step S66, fuel injection is performed with alcohol-mixed fuel.

  As described above, in the fuel supply control device for an internal combustion engine according to the third embodiment, one fuel separated by the fuel separation device 55 and stored in the sub fuel tank 47 is supplied to the internal combustion engine, and then supplied to the internal combustion engine. It is determined whether or not the difference between the supply amount of gasoline fuel to be supplied and the supply amount of alcohol fuel exceeds a predetermined amount set in advance, that is, the supply amount of gasoline fuel from the remaining amount of the mixed fuel stored in the main fuel tank 47 When the value obtained by subtracting exceeds a predetermined amount set in advance, the other fuel separated by the fuel separation device 55 is stored in the sub fuel tank 51 and supplied to the internal combustion engine.

  Therefore, for example, when an operating condition in which it is better to supply gasoline fuel in an internal combustion engine is satisfied, the gasoline fuel separated by the fuel separator 55 is stored in the sub fuel tank 47 and supplied to the internal combustion engine. Thereafter, when the operating condition in which it is better to supply gasoline fuel to the internal combustion engine is released, or when the value obtained by subtracting the supply amount of gasoline fuel from the remaining amount of fuel mixed in the main fuel tank 47 exceeds a predetermined amount, The alcohol fuel separated by the fuel separator 55 is stored in the sub fuel tank 51 and supplied to the internal combustion engine. Therefore, the alcohol concentration of the mixed fuel stored in the main fuel tank 47 is maintained at a predetermined concentration, and a fuel having a property suitable for the operating state of the internal combustion engine, that is, gasoline fuel or alcohol fuel is selectively selected at all times. It can be used, and it is possible to improve the cold start performance and performance at high rotation and high load.

  Further, when the value obtained by subtracting the gasoline fuel supply amount from the remaining amount of the mixed fuel in the main fuel tank 47 exceeds a predetermined amount, the supply of the gasoline fuel to the internal combustion engine is stopped and the alcohol fuel supply is started. In addition, the alcohol concentration LA in the mixed fuel in the main fuel tank 47 can be quickly restored to the alcohol concentration L before the start of control, and highly accurate fuel supply control can be performed.

  In the above-described embodiment, the fuel injection control at the low temperature start of the internal combustion engine has been described in detail. However, the same operational effects can be achieved even at high rotation and high load. In this case, the alcohol fuel separated by the fuel separation device 55 is stored in the sub fuel tank 51 and supplied to the internal combustion engine when the operating condition for supplying the alcohol fuel is satisfied at the time of high rotation and high load of the internal combustion engine. Thereafter, when the operating condition for supplying alcohol fuel to the internal combustion engine is released, the gasoline fuel separated by the fuel separator 55 is stored in the sub fuel tank 51 and supplied to the internal combustion engine.

  Moreover, although the internal combustion engine of this invention was demonstrated as a port injection type engine in the Example mentioned above, a cylinder injection type engine may be sufficient.

  As described above, the fuel supply control device for an internal combustion engine according to the present invention is intended to improve performance by selectively using a fuel having properties suitable for the operating state of the internal combustion engine. It is also useful for institutions.

1 is a schematic configuration diagram illustrating a fuel supply control device for an internal combustion engine according to a first embodiment of the present invention. 3 is a flowchart showing mixed fuel separation and supply control by the fuel supply control device for the internal combustion engine of the first embodiment. It is a flowchart showing the mixed fuel separation supply control by the fuel supply control apparatus of the internal combustion engine which concerns on Example 2 of this invention. It is a flowchart showing the mixed fuel separation supply control by the fuel supply control apparatus of the internal combustion engine which concerns on Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 18 Combustion chamber 19 Intake port 20 Exhaust port 31 Intake pipe 34 Electronic throttle device 36 Exhaust pipe 43 Injector 45 Fuel supply pipe 46 Spark plug 47 Main fuel tank 50 Main fuel supply pipe 51 Sub fuel tank 53 Sub fuel supply pipe 54 Supply fuel switching Valve 55 Fuel separator 57 Shut-off valve 59 First separated fuel switching valve 63 Second separated fuel switching valve 66 Electronic control unit, ECU
72 Water temperature sensor 74, 76 Remaining amount sensor 75 Concentration sensor

Claims (7)

The mixed fuel stored in the main fuel tank is separated into alcohol fuel and hydrocarbon fuel by the fuel separator, and one separated fuel is supplied to the sub fuel tank and the other fuel is returned to the main fuel tank. In the fuel supply control device for an internal combustion engine capable of supplying the fuel stored in the main fuel tank or the sub fuel tank to the internal combustion engine,
After supplying one fuel separated by the fuel separation device and stored in the sub fuel tank to the internal combustion engine, the other fuel separated by the fuel separation device is stored in the sub fuel tank and stored in the internal combustion engine. A fuel supply control device for an internal combustion engine, characterized by being supplied to an engine.   When the operating state of the internal combustion engine enters one fuel use region, the fuel separation device separates the mixed fuel, and the separated fuel is stored in the sub fuel tank and stored in the sub fuel tank. 2. The fuel supply control device for an internal combustion engine according to claim 1, wherein supply of the other fuel to the internal combustion engine is started.   When the operating state of the internal combustion engine deviates from one fuel use region, one fuel separated by the fuel separator is returned to the main fuel tank, and the other fuel is stored in the sub fuel tank. The fuel supply control device for an internal combustion engine according to claim 1 or 2, wherein the supply of the other fuel stored in the fuel tank to the internal combustion engine is started.   When the supply amount of one fuel supplied to the internal combustion engine exceeds a predetermined amount set in advance, one fuel separated by the fuel separator is returned to the main fuel tank, and the other fuel is returned to the sub fuel tank. The fuel supply control device for an internal combustion engine according to claim 1 or 2, wherein supply of the other fuel stored in the sub fuel tank to the internal combustion engine is started.   When the difference between the supply amount of one fuel supplied to the internal combustion engine and the supply amount of the other fuel exceeds a predetermined amount set in advance, the one fuel separated by the fuel separator is transferred to the main fuel tank. 5. The other fuel is stored in the sub fuel tank, and the supply of the other fuel stored in the sub fuel tank to the internal combustion engine is started. A fuel supply control device for an internal combustion engine according to claim 1.   6. The internal combustion engine according to claim 1, wherein when the alcohol concentration of the main fuel tank reaches a predetermined concentration set in advance, the supply of the other fuel to the internal combustion engine is terminated. Fuel supply control device.   When the alcohol concentration in the main fuel tank reaches a predetermined concentration set in advance and the other fuel stored in the sub fuel tank is exhausted, the mixed fuel stored in the main fuel tank is supplied to the internal combustion engine. The fuel supply control device for an internal combustion engine according to claim 6, wherein

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