WO2014091678A1 - Fuel injection control device for internal combustion engine - Google Patents

Fuel injection control device for internal combustion engine Download PDF

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Publication number
WO2014091678A1
WO2014091678A1 PCT/JP2013/006770 JP2013006770W WO2014091678A1 WO 2014091678 A1 WO2014091678 A1 WO 2014091678A1 JP 2013006770 W JP2013006770 W JP 2013006770W WO 2014091678 A1 WO2014091678 A1 WO 2014091678A1
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WIPO (PCT)
Prior art keywords
fuel
injection
pressure
valve
gas
Prior art date
Application number
PCT/JP2013/006770
Other languages
French (fr)
Japanese (ja)
Inventor
優一 竹村
溝渕　剛史
和田　実
和賢 野々山
福田　圭佑
Original Assignee
株式会社デンソー
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Publication of WO2014091678A1 publication Critical patent/WO2014091678A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B43/00—Engines characterised by operating on gaseous fuels; Plants including such engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
    • F02D19/0602—Control of components of the fuel supply system
    • F02D19/0613—Switch-over from one fuel to another
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D37/00—Non-electrical conjoint control of two or more functions of engines, not otherwise provided for
    • F02D37/02—Non-electrical conjoint control of two or more functions of engines, not otherwise provided for one of the functions being ignition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0002—Controlling intake air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0248—Injectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0248—Injectors
    • F02M21/0257—Details of the valve closing elements, e.g. valve seats, stems or arrangement of flow passages
    • F02M21/026—Lift valves, i.e. stem operated valves
    • F02M21/0263—Inwardly opening single or multi nozzle valves, e.g. needle valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B43/00—Engines characterised by operating on gaseous fuels; Plants including such engines
    • F02B43/10—Engines or plants characterised by use of other specific gases, e.g. acetylene, oxyhydrogen
    • F02B2043/103—Natural gas, e.g. methane or LNG used as a fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F02D2041/224—Diagnosis of the fuel system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0602—Fuel pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/60—Input parameters for engine control said parameters being related to the driver demands or status
    • F02D2200/602—Pedal position
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/31—Control of the fuel pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0027—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures the fuel being gaseous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/04—Introducing corrections for particular operating conditions
    • F02D41/12—Introducing corrections for particular operating conditions for deceleration
    • F02D41/123—Introducing corrections for particular operating conditions for deceleration the fuel injection being cut-off
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present disclosure relates to a fuel injection control device for an internal combustion engine, and more particularly to a fuel injection control device for an in-vehicle internal combustion engine including a fuel supply system capable of supplying gas fuel and liquid fuel, respectively.
  • a fuel supply system that supplies gas fuel to a fuel injection valve is provided in the middle of a fuel tank that connects the gas tank and the fuel injection means, and a gas tank that stores the gas fuel in a high pressure state.
  • a pressure regulating valve that depressurizes and adjusts the pressure of the supplied gas fuel, and a shutoff valve that is provided upstream of the pressure regulating valve (on the gas tank side) and blocks the flow of the gas fuel to the pressure regulating valve.
  • Patent Document 1 when the pressure regulating valve malfunctions and the pressure of the gas fuel supplied to the fuel injection valve exceeds a predetermined value, the shutoff valve is closed to the downstream side of the pressure regulating valve.
  • the gas fuel supply is shut off and the fuel gas is injected from the fuel injection valve. If the pressure of the gas fuel supplied to the fuel injection valve becomes lower than a predetermined value due to the injection of gas fuel with the shut-off valve closed, the shut-off valve is opened to adjust the pressure. It is disclosed that gas fuel is supplied downstream from the valve.
  • Gas fuel density (gas density) varies depending on fuel pressure. Therefore, depending on the supply pressure (injection pressure) of the gas fuel to the fuel injection valve, it is conceivable that the injection fuel becomes excessive by injecting the gas fuel with the shut-off valve closed.
  • an internal combustion engine capable of performing appropriate fuel injection control even when the injection pressure is higher than a set pressure.
  • the main object of the present invention is to provide a fuel injection control device.
  • the present disclosure includes a first injection unit that injects gas fuel, a second injection unit that injects liquid fuel, a fuel passage that supplies the gas fuel, and a gas fuel that is supplied to the first injection unit.
  • a fuel comprising: a pressure regulating valve that adjusts the pressure to a predetermined set pressure; and a shut-off control valve that is provided upstream of the pressure regulating valve in the fuel passage and has a shut-off function that shuts off the flow of the gas fuel.
  • the present invention relates to a fuel injection control device for an internal combustion engine that is applied to an injection system and performs switching between injection of gas fuel by a first injection means and injection of liquid fuel by a second injection means.
  • the fuel injection control device determines whether the supply pressure, which is the pressure of the gas fuel supplied to the first injection means, has exceeded a predetermined first determination value on the higher pressure side than the set pressure.
  • the determination means and the first determination means determine that the supply pressure exceeds the first determination value, the shut-off control valve is closed and the internal combustion engine is operated according to the operating load.
  • Fuel switching means for switching from injection of gas fuel by the first injection means to injection of liquid fuel by the second injection means.
  • gas fuel leaks from the upstream side to the downstream side when, for example, foreign matter or the like is caught in the closed state, and the fuel pressure on the downstream side, that is, the gas to the first injection means is caused by the fuel leak.
  • injection pressure injection pressure
  • the injection pressure and the gas density are in a proportional relationship, and the gas density increases as the injection pressure increases. Therefore, when the injection pressure is high, the injected fuel may become excessive in a low load state of the internal combustion engine due to the high pressure state.
  • FIG. 1 is a configuration diagram showing an outline of an engine fuel injection system.
  • FIG. 2 is a diagram showing a schematic configuration of the first injection valve.
  • FIG. 3 is a diagram illustrating a schematic configuration of a regulator.
  • FIG. 4 is a diagram showing a relationship between a supply gas pressure to the first injection valve and a fuel use region.
  • FIG. 5 is a flowchart showing a procedure of fuel injection processing in the first embodiment.
  • FIG. 6 is a diagram showing the relationship between the injection pressure and the minimum fuel amount Qmin.
  • FIG. 7 is a time chart showing a specific aspect of the fuel injection processing of the first embodiment.
  • FIG. 8 is a time chart showing a specific aspect of the fuel injection processing of the first embodiment.
  • FIG. 1 is a configuration diagram showing an outline of an engine fuel injection system.
  • FIG. 2 is a diagram showing a schematic configuration of the first injection valve.
  • FIG. 3 is a diagram illustrating a schematic configuration of a regulator.
  • FIG. 4 is
  • FIG. 9 is a time chart showing a specific aspect of the fuel injection process of the second embodiment.
  • FIG. 10 is a flowchart showing a procedure of fuel injection processing in the second embodiment.
  • FIG. 11 is a time chart showing a specific aspect of the fuel injection process of the third embodiment.
  • the intake system 11 is an inline three-cylinder spark ignition engine, and an intake system 11 and an exhaust system 12 are connected to an intake port and an exhaust port, respectively.
  • the intake system 11 has an intake manifold 13 and an intake pipe 14.
  • the intake manifold 13 has a plurality of (for the number of cylinders of the engine 10) branch pipe portions 13a connected to the intake port of the engine 10, and a collective portion 13b connected to the intake pipe 14 on the upstream side. ing.
  • the intake pipe 14 is provided with a throttle valve 15 as air amount adjusting means.
  • the throttle valve 15 is configured as an electronically controlled throttle valve whose opening degree is adjusted by a throttle actuator 15a such as a DC motor.
  • the opening degree of the throttle valve 15 (throttle opening degree) is detected by a throttle opening degree sensor 15b incorporated in the throttle actuator 15a.
  • the exhaust system 12 has an exhaust manifold 16 and an exhaust pipe 17.
  • the exhaust manifold 16 has a plurality of (for the number of cylinders of the engine 10) branch pipe portions 16a connected to the exhaust port of the engine 10 and a collecting portion 16b connected to the exhaust pipe 17 on the downstream side. ing.
  • the exhaust pipe 17 is provided with an exhaust sensor 18 for detecting exhaust components and a catalyst 19 for purifying exhaust.
  • an air-fuel ratio sensor that detects the air-fuel ratio from the oxygen concentration in the exhaust gas is provided.
  • a spark plug 20 is provided in each cylinder of the engine 10.
  • a high voltage is applied to the ignition plug 20 at a desired ignition timing through an ignition device 20a including an ignition coil. By applying this high voltage, a spark discharge is generated between the opposing electrodes of each spark plug 20, and the fuel introduced into the cylinder (combustion chamber) is ignited and used for combustion.
  • the present system is a fuel injection means for injecting and supplying fuel to the engine 10, a first injection valve 21 for injecting gas fuel (CNG fuel), and a second injection valve 22 for injecting liquid fuel (gasoline). And have.
  • Each of these injection valves 21 and 22 injects fuel into the branch pipe portion 13a of the intake manifold 13 in the intake system 11, and gas fuel is supplied to the intake port of each cylinder by the injection of the first injection valve 21.
  • the liquid fuel is supplied to the intake port of each cylinder by the injection of the second injection valve 22.
  • Each of the injection valves 21 and 22 is an open / close type control valve in which the valve body is lifted from the closed position to the open position by electrically driving the electromagnetic drive unit. Each valve is driven to open by a valve opening drive signal. These injection valves 21 and 22 are opened by energization and closed by energization interruption. An amount of fuel (gas fuel, liquid fuel) corresponding to the energization time is injected from each of the injection valves 21 and 22.
  • the injection pipe 23 is connected to the tip of the first injection valve 21, and the gas fuel injected from the first injection valve 21 is branched through the injection pipe 23. 13a is injected.
  • FIG. 2A shows a non-injection state
  • FIG. 2B shows an injection state.
  • the first injection valve 21 has a self-sealing structure in which the closing sealing performance is enhanced by the pressure of the gas fuel supplied to itself.
  • the first injection valve 21 has a cylindrical body 31.
  • a valve body 32 is slidably accommodated in the body 31, and the valve body 32 is biased in the valve closing direction by a spring 33 in the body 31.
  • the nozzle hole 34 provided at the tip of the injection valve is closed by the tip of the valve body 32.
  • a first fuel chamber 35 is provided on the rear end side (upstream side) of the valve body 32
  • a second fuel chamber 36 is provided on the front end side (downstream side) of the valve body 32. It has been.
  • the valve body 32 is provided with a small-diameter portion 32a on the tip side of the sliding portion, and a second fuel chamber 36 is provided around the small-diameter portion 32a.
  • the first fuel chamber 35 and the second fuel chamber 36 are in communication with each other via a fuel passage 37 provided in the valve body 32.
  • the inlet side of the fuel passage 37 communicates with the first fuel chamber 35, and the outlet side thereof It leads to the second fuel chamber 36.
  • the valve body 32 is displaced to the valve opening position in response to energization to the electromagnetic drive unit 38 composed of a solenoid or the like.
  • gas fuel is supplied from a regulator 43 described later to the first fuel chamber 35, and the gas fuel is also introduced into the second fuel chamber 36 through the fuel passage 37.
  • the valve element 32 is displaced to the valve opening position against the urging force of the spring 33 as the electromagnetic drive unit 38 is energized, the nozzle hole 34 is opened, and the gas fuel is discharged. Be injected.
  • the valve body 32 is provided with a small-diameter portion 32 a on the distal end side thereof, so that the pressure receiving area on the first fuel chamber 35 side and the pressure receiving side on the second fuel chamber 36 side in the valve-closed state.
  • the relationship of the areas is “pressure receiving area on the first fuel chamber 35 side> pressure receiving area on the second fuel chamber 36 side” (see FIG. 2A). Therefore, in the valve closing state shown in FIG. 2A, the pressure of the gas fuel supplied from the regulator 43 side (corresponding to the injection pressure) is in the direction in which the valve body 32 is closed (valve closing direction). It comes to act more greatly.
  • the injection pressure also acts on the end face (the lower end face in the figure) of the small-diameter portion 32a, so that the fuel pressure in the valve closing direction acting on the valve body 32 and the valve opening direction are also applied.
  • the fuel pressure is almost the same.
  • the configuration of the gas fuel supply unit 40 that supplies the gas fuel to the first injection valve 21 and the liquid fuel supply unit 70 that supplies the liquid fuel to the second injection valve 22. Will be described.
  • a gas tank 42 is connected to the first injection valve 21 via a gas pipe 41, and the pressure of the gas fuel supplied to the first injection valve 21 is in the middle of the gas pipe 41.
  • a regulator 43 having a pressure adjusting function for adjusting the pressure under pressure.
  • the regulator 43 (the pressure adjusting valve 60) is configured such that a gas fuel in a high pressure state (for example, a maximum of 20 MPa) stored in the gas tank 42 is a predetermined set pressure (for example, 0.2 to 1) that is the injection pressure of the first injection valve 21.
  • the pressure is adjusted to a constant pressure within a range of 0.0 MPa, in this embodiment, 0.3 ⁇ ⁇ (MPa).
  • the gas fuel after the decompression adjustment is supplied to the first injection valve 21 through the gas pipe 41.
  • the upstream side of the regulator 43 is a high-pressure pipe portion 41a that forms a high-pressure side passage
  • the downstream side is a low-pressure pipe portion 41b that forms a low-pressure side passage.
  • the gas fuel passage formed by the gas pipe 41 and the like further includes a tank main stop valve 44 (tank outlet valve) disposed in the vicinity of the fuel outlet of the gas tank 42 and a downstream side of the tank main stop valve 44.
  • a shutoff valve 45 disposed near the fuel inlet of the regulator 43 is provided, and the flow of gas fuel in the gas pipe 41 is allowed and shut off by these valves 44 and 45.
  • Both the tank main stop valve 44 and the shut-off valve 45 are electromagnetic on-off valves, and are normally closed so that the flow of gas fuel is cut off when not energized and the flow of gas fuel is allowed when energized.
  • the tank main stop valve 44 and the shutoff valve 45 correspond to a “shutoff control valve”.
  • a pressure sensor 46 for detecting the fuel pressure and a temperature sensor 47 for detecting the fuel temperature are provided in the high pressure pipe portion 41a of the gas pipe 41, and a pressure sensor 48 for detecting the fuel pressure is provided in the low pressure pipe portion 41b.
  • a temperature sensor 49 for detecting the temperature is provided.
  • the shut-off valve 45 and the pressure sensor 46 can be provided integrally with the regulator 43. In this embodiment, a configuration in which the shut-off valve 45 and the pressure sensor 46 are provided integrally with the regulator 43 is adopted.
  • the regulator 43 constitutes a mechanical pressure adjusting device that adjusts the fuel pressure in the low-pressure pipe portion 41b with respect to the set pressure.
  • the regulator 43 has a high-pressure passage 51 connected to the high-pressure pipe section 41a and a low-pressure passage 52 connected to the low-pressure pipe section 41b. And a pressure sensor 46 are provided.
  • the pressure sensor 46 detects the pressure of the gas fuel upstream of the shutoff valve 45.
  • Reference numeral 53 is a filter for removing foreign matter.
  • the configuration of the shut-off valve 45 is substantially the same as the configuration of the first injection valve 21 and has a self-sealing structure. The configuration will be briefly described.
  • the shut-off valve 45 has a valve body 55 biased in the valve closing direction by a spring 54, and the valve body 55 is closed against the biasing force of the spring 54 by energizing the electromagnetic drive unit 56. The valve is displaced from the position to the valve opening position.
  • a first fuel chamber 57 is provided on the rear end side (upstream side) of the valve body 55, and a second fuel chamber 58 is provided on the distal end side (downstream side where the small diameter portion is provided) of the valve body 55. Yes.
  • Both the fuel chambers 57 and 58 are communicated with each other through a fuel passage 59 provided in the valve body 55.
  • high-pressure gas fuel is supplied to both the fuel chambers 57 and 58 from the gas tank 42, and in the closed state of the shutoff valve 45, a closing force is applied to the valve body 55 by the fuel pressure on the gas tank 42 side. .
  • the valve element 55 is displaced to the valve open position against the biasing force of the spring 54 with the energization of the electromagnetic drive unit 56 (as shown), high-pressure gas fuel flows downstream.
  • a pressure regulating valve 60 is provided on the downstream side of the shutoff valve 45.
  • a valve body chamber 61 is provided in the high pressure passage 51, and a valve body 62 is accommodated in the valve body chamber 61.
  • the valve body 62 opens and closes a valve seat portion 63 that is an inlet portion of the low pressure passage 52. If the valve body 62 is in the open position, the valve seat 63 is opened and the high pressure passage 51 and the low pressure passage 52 are communicated. If the valve body 62 is in the closed position, the valve seat 63 is closed and the communication between the high pressure passage 51 and the low pressure passage 52 is blocked.
  • the valve body 62 is opened and closed according to the fuel pressure (corresponding to the injection pressure) in the low-pressure passage 52 and the force in the valve opening direction generated by the valve body operating portion 65.
  • the valve element actuating portion 65 is a space that is open to the atmosphere, and has an air opening portion 67 in which an adjustment spring 66 is provided, and a diaphragm as a partition member that partitions the air release portion 67 and the low-pressure passage 52. 68.
  • the diaphragm 68 is provided integrally with the valve body 62. Fuel pressure in the low pressure passage 52 acts on the diaphragm 68 as a force in the valve closing direction, and an urging force of the adjustment spring 66 and atmospheric pressure act as a force in the valve opening direction.
  • the valve body 62 is held in the valve closing position.
  • the valve element 62 opens with the displacement of the diaphragm 68.
  • the opening position (valve lift amount) of the valve body 62 is determined according to the difference between the force in the valve closing direction and the force in the valve opening direction, and the opening area of the valve seat 63 is changed according to the opening position. Is done. Further, the amount of fuel flowing from the high pressure passage 51 into the low pressure passage 52 is adjusted by changing the opening area.
  • a relief valve 69 that vents gas when the fuel pressure in the low pressure passage 52 becomes abnormally high is provided in the branch portion 52a branched from the low pressure passage 52.
  • the relief valve 69 is mechanically driven, and opens when the fuel pressure in the low pressure passage 52 becomes higher than a predetermined relief pressure Pref.
  • the pressure adjusting means is constituted by the pressure adjusting valve 60 made up of components such as the valve body 62 and the valve body operating portion 65.
  • the shut-off valve 45, the pressure sensor 46, and the pressure adjustment valve 60 are integrally provided.
  • the shut-off valve 45 and the pressure sensor 46 are separated from the regulator 43 in the high-pressure piping portion 41 a. It is also possible to provide it.
  • a fuel tank 72 is connected to the second injection valve 22 via a fuel pipe 71.
  • the fuel pipe 71 is provided with a fuel pump 73 that feeds the liquid fuel in the fuel tank 72 to the second injection valve 22.
  • the control unit 80 includes a CPU 81, a ROM 82, a RAM 83, a backup RAM 84, an interface 85, and a bidirectional bus 86.
  • the CPU 81, ROM 82, RAM 83, backup RAM 84, and interface 85 are connected to each other by a bidirectional bus 86.
  • the CPU 81 executes a routine (program) for controlling the operation of each unit in the system.
  • the ROM 82 stores in advance various data such as a routine executed by the CPU 81, maps (including tables, relational expressions, etc. in addition to maps) and parameters referred to when the routine is executed.
  • the RAM 83 temporarily stores data as necessary when the CPU 81 executes a routine.
  • the backup RAM 84 appropriately stores data under the control of the CPU 81 in a state where the power is turned on, and retains the stored data even after the power is shut off.
  • the interface 85 includes sensors (crank angle sensor, air flow meter, cooling water temperature sensor, etc.) provided in the present system, including the throttle opening sensor 15b, the exhaust sensor 18, the pressure sensors 46, 48, and the temperature sensors 47, 49 described above. Vehicle speed sensors, accelerator sensors, etc.) are electrically connected, and outputs (detection signals) from these sensors are transmitted to the CPU 81.
  • the interface 85 is electrically connected to driving units such as the throttle actuator 15a, the ignition device 20a, the injection valves 21 and 22, the tank main stop valve 44, the shutoff valve 45, and the like, and drives these driving units. Therefore, the drive signal sent from the CPU 81 is output toward the drive unit. That is, the control unit 80 acquires the operating state of the engine 10 based on the output signals of the above-described sensors, and performs the above-described driving unit control based on this operating state.
  • the intake air amount of the engine 10 is calculated based on the accelerator operation amount detected by the accelerator sensor, the engine rotational speed detected by the crank angle sensor, and the like, and the throttle actuator 15a is calculated based on the calculated value. Control the drive. Further, the fuel injection amount (fuel injection time) is calculated based on the engine speed and the intake air amount detected by the air flow meter, and the driving of the injection valves 21 and 22 is controlled based on the calculated value. Further, the optimal ignition timing is calculated based on the engine rotation speed, the intake air amount, and the like, and the drive of the ignition device 20a is controlled so that ignition is performed at the optimal ignition timing.
  • a control signal is input from the control unit 80 to the ignition device 20a, the tank main stop valve 44, and the shutoff valve 45.
  • the ignition device 20a outputs a high voltage in response to a control signal from the control unit 80, and generates an ignition spark in the ignition plug.
  • the tank main stop valve 44 and the shutoff valve 45 are independently switched from the closed state to the open state in accordance with a control signal from the control unit 80.
  • the control unit 80 selectively switches the fuel to be used according to the engine operating state, the fuel remaining amount in the tank, an input signal from a fuel selection switch (not shown), and the like. Specifically, when the remaining amount of the gas fuel in the gas tank 42 falls below a predetermined value or when the use of the liquid fuel is selected by the fuel selection switch, the liquid fuel is preferentially used. When the remaining amount of liquid fuel in the fuel tank 72 falls below a predetermined value or when the use of gas fuel is selected by the fuel selection switch, the gas fuel is preferentially used.
  • the pressure adjusting valve 60 of the regulator 43 when a foreign object is caught in the valve seat 63, the pressure adjusting valve 60 is always kept open by an opening degree corresponding to the size of the foreign object. That is, the pressure regulating valve 60 is not completely closed, and the high pressure side and the low pressure side of the fuel passage are in communication with each other. In this case, for example, in a low load operation state such as during idle operation, the amount of fuel leaking from the high pressure side to the low pressure side is greater than the amount of fuel injected from the first injection valve 21, thereby There is a possibility that the supply gas pressure (injection pressure) to the injection valve 21 may increase unintentionally.
  • the minimum amount of gas fuel that can be injected by the first injection valve 21 increases, and as a result, the fuel injection amount becomes excessive in a low-load operation state. That is, since the pressure of the gas fuel and the gas density are in a proportional relationship, the higher the supply gas pressure to the first injection valve 21, the more the actual fuel injection amount even at the same injection time (injection valve energization time). As a result, the minimum amount of fuel that can be injected from the first injection valve 21 increases.
  • examples of the foreign matter that bites into (adheres to) the valve seat portion 63 include a liquefied substance that is generated by liquefaction due to a depressurization action when gas fuel passes through the valve seat portion 63 in the pressure regulating valve 60. Since the gas fuel contains an oil component, the liquefied substance becomes a highly viscous substance containing the oil component. In the pressure regulating valve 60, such a highly viscous substance adheres to the valve seat portion 63 to be opened by a predetermined opening, and fuel leakage from the high pressure side to the low pressure side occurs. Such inconvenience can be considered to occur even when a filter is provided on the upstream side of the pressure regulating valve 60.
  • the supply gas pressure to the first injection valve 21 becomes a high pressure state exceeding a predetermined value (determination value K1)
  • at least one of the cutoff control valve (the tank main stop valve 44 and the cutoff valve 45). 1) is closed, and the use of gas fuel is restricted according to the engine load.
  • the fuel injection from the first injection valve 21 to the second injection valve 22 Select whether or not to switch to fuel injection.
  • fuel injection by the first injection valve 21 becomes possible when proper fuel injection is possible even with the supply gas pressure to the first injection valve 21 at that time. That is, the use of gas fuel is resumed.
  • FIG. 4 is a schematic diagram showing the relationship between the gas pressure supplied to the first injection valve 21 and the fuel use area.
  • the horizontal axis of FIG. 4 shows the supply gas pressure to the first injection valve 21, and the vertical axis shows the magnitude of the engine load.
  • a large engine load corresponds to an increase in the required fuel amount per combustion.
  • the set pressure Preg indicated by the broken line L1 is a pressure value adjusted by the pressure adjusting valve 60 to reduce the pressure.
  • the determination value K1 is determined on the higher pressure side than the set pressure Preg.
  • the determination value K1 is determined in consideration of the minimum fuel amount Qmin that can be injected from the first injection valve 21 during idle operation. Specifically, in the region where the supply gas pressure to the first injection valve 21 is equal to or higher than the determination value K1, the minimum fuel amount Qmin increases due to the increase in gas density, and the gas fuel by the first injection valve 21 increases. It means that when the injection is performed, the actual fuel injection amount becomes excessive than the required fuel amount Qa determined according to the engine load, that is, “minimum fuel amount Qmin> required fuel amount Qa”. To do.
  • the required fuel amount Qa differs depending on the engine load, and the required fuel amount Qa increases as the load becomes higher.
  • the use area of the gas fuel and the use area of the liquid fuel are determined. Specifically, as indicated by a solid line L2 in FIG. 4, within the range of the supply gas pressure in which the operation of the first injection valve 21 is allowed (in the region on the low pressure side than the operating limit pressure Plim), the high load side The use of gas fuel is allowed, in other words, the use of gas fuel is restricted on the lower load side.
  • a region where the use of gas fuel is restricted in a region where the injection pressure exceeds the determination value K ⁇ b> 1 is indicated by hatching. Note that the operating limit pressure Plim is set higher than the relief pressure.
  • the use area of the gas fuel and the use area of the liquid fuel are set on the lower pressure side than the set pressure Preg.
  • the boundary line of the use region is indicated by a solid line L3.
  • the region where the supply gas pressure is high is the gas fuel use region, and the low pressure side is the liquid fuel use region.
  • the region where the supply gas pressure is high is the gas fuel use region, and the low pressure side is the liquid fuel use region.
  • step S100 it is determined whether or not the injection pressure detected by the pressure sensor 48 is greater than or equal to a determination value K1 (first determination means). If “injection pressure ⁇ determination value K1”, the process proceeds to step S101, and it is determined whether or not an opening command for opening the shutoff valve 45 is being output. When the open command is being output, the process proceeds to step S102, where a close command for closing the tank main stop valve 44 is output, and in step S103, a close command for closing the shutoff valve 45 is output.
  • the required fuel amount Qa per combustion is calculated based on the engine operating state (here, engine load and engine speed). Further, based on the injection pressure detected by the pressure sensor 48 (supply gas pressure to the first injection valve 21), a minimum fuel amount Qmin, which is the minimum injection amount that can be injected from the first injection valve 21, is calculated.
  • the relationship between the injection pressure and the minimum fuel amount Qmin is stored in advance as a calculation map, and the minimum fuel amount Qmin is calculated using the calculation map.
  • FIG. 6 shows an example of the calculation map. In FIG. 6, the minimum fuel amount Qmin increases as the injection pressure increases.
  • step S105 the required fuel amount Qa is compared with the minimum fuel amount Qmin.
  • the process proceeds to step S106, and fuel injection by the first injection valve 21, that is, use of gas fuel is selected.
  • step S107 fuel injection by the second injection valve 22, that is, use of liquid fuel is selected (fuel switching means). Then, this process ends.
  • step S100 it is determined in step S100 that “injection pressure ⁇ determination value K1”, and in step S101, the opening command for the shutoff valve 45 is not being output, that is, the closing command for closing the shutoff valve 45 is being output. If it is determined, the process proceeds to step S108.
  • step S108 it is determined whether or not the injection pressure exceeds a determination value K2 (second determination means).
  • the determination value K2 is determined on the higher pressure side than the set pressure Preg and the determination value K1, and in this embodiment, is determined on the lower pressure side than the relief pressure Pref and the operation limit pressure Plim (FIG. 4). reference). If “injection pressure ⁇ determination value K2”, the processing of steps S104 to S107 is executed.
  • step S109 where the intake air amount of the engine 10 is increased and corrected, and in step S110, the ignition timing is corrected to the retard side with respect to the optimal ignition timing ( Operation change means). Thereafter, the processing of steps S104 to S107 is executed, and this processing is terminated.
  • step S106 corresponds to “gas switching means”.
  • the process proceeds to step S111, and it is determined whether or not a closing command for closing the shutoff valve 45 is being output.
  • the process proceeds to step S112, and it is determined whether or not the injection pressure is lower than the determination value K3 (third determination means).
  • the determination value K3 is determined to be lower than the determination value K1.
  • the determination value K3 is determined to be the minimum value of the injection pressure that can secure the injection amount necessary to keep the engine 10 in the operating state. It has been. If “injection pressure ⁇ determination value K3”, the process is temporarily terminated.
  • step S113 the process proceeds to step S113 to output an opening command for opening the shut-off valve 45, and in subsequent step S114, an opening command for opening the tank main stop valve 44 is output. . Then, this process ends.
  • FIG. 7 assumes a case in which foreign matter is caught in the valve seat portion 63 of the pressure regulating valve 60 and the injection pressure exceeds the determination value K1 during low load operation (for example, during idle operation) using gas fuel. is doing. Since the engine is in operation, the tank main stop valve 44 and the shutoff valve 45 are open before the injection pressure exceeds the determination value K1.
  • the tank main stop valve 44 is closed at the timing t11, and then the shutoff valve 45 is closed.
  • the reason for shifting the valve closing timing of each other is to prevent the valves from becoming difficult to open due to a decrease in battery voltage due to overlapping driving timings of the tank main stop valve 44 and the shutoff valve 45. is there.
  • the tank main stop valve 44 is closed first, that is, the gas pipe 41 is closed first from the upstream side in order to suppress fluctuations in the injection pressure accompanying the closing of the valves 44 and 45. .
  • the minimum fuel amount Qmin is larger than the required fuel amount Qa for the first injection valve 21
  • the liquid fuel by the second injection valve 22 is injected from the gas fuel injection by the first injection valve 21. Switch to injection.
  • the shutoff valve 45 is opened at the timing t14, and then the tank main stop valve 44 is opened. Thereby, supply of the gas fuel to the 1st injection valve 21 is permitted, and an injection pressure rises.
  • the determination value K3 is set within the use region of the gas fuel (see FIG. 4), and thereby, the supply gas pressure is prevented from excessively decreasing.
  • the determination value K3 is set to a lower pressure side than the set pressure Preg. By doing so, the foreign matter adhering to the valve seat 63 is removed by increasing the opening of the pressure regulating valve 60 and increasing the gas flow rate when the shut-off valve 45 is switched to the open state. .
  • the injection pressure further increases.
  • the pressure is increased and becomes higher than the determination value K2.
  • the first injection valve 21 may be difficult to open due to the high pressure of the low pressure passage portion (low pressure pipe portion 41b, low pressure passage 52) between the pressure regulating valve 60 and the first injection valve 21. is there.
  • the reason why the first injection valve 21 is difficult to open in the high pressure state of the low pressure passage portion is as follows. That is, the first injection valve 21 is provided with a force in the closing direction by the pressure of the gas fuel from the low pressure passage portion in the closed state, and blocks the flow of the gas fuel by the force in the closing direction. Therefore, when the first injection valve 21 is opened, it is necessary to generate a driving force that overcomes the fuel pressure. On the other hand, if the pressure of the gas fuel in the low pressure passage is in a high pressure state, a force in the closing direction acts greatly on the first injection valve 21, and even if a valve opening drive signal is output to the first injection valve 21, There is a possibility that the one injection valve 21 cannot be opened.
  • the throttle opening is driven to the valve opening side at the timing t22, and the suction is performed.
  • the ignition timing is changed to the retarded side in order to suppress an increase in torque due to the increase in the intake air amount.
  • the increase correction of the intake air amount is performed according to the engine load, and the correction amount is increased toward the lower load side so that “required fuel amount Qa> minimum fuel amount Qmin”.
  • the required fuel amount Qa increases, and at timing t23 after “required fuel amount Qa> minimum fuel amount Qmin”, the liquid fuel used by the second injection valve 22 is changed to the gas generated by the first injection valve 21. Switch to using fuel. That is, consumption of gas fuel is promoted by fuel injection from the first injection valve 21. At this time, since the tank main stop valve 44 and the shut-off valve 45 remain closed, the injection pressure is reduced by the injection of gas fuel by the first injection valve 21.
  • the shutoff valve 45 is opened at the timing t24, and then the tank main stop valve 44 is opened. Further, after the injection pressure is adjusted to the set pressure Preg as the valves 44 and 45 are opened, the increase correction of the intake air amount is canceled and the ignition retard is also released.
  • the tank main stop valve 44 and the shutoff valve 45 as shutoff control valves are closed, and the use of gas fuel is restricted according to the engine load.
  • the configuration is switched to using fuel. Since the gas density increases as the injection pressure increases, the use of gas fuel when the injection pressure is high may result in an excess of injected fuel in a low load state of the engine 10. In that respect, according to the above configuration, it is possible to avoid an excessive amount of injected fuel. Therefore, appropriate fuel injection control can be performed even when the injection pressure is higher than the set pressure.
  • the minimum fuel amount Qmin determined according to the injection pressure is compared with the required fuel amount Qa determined according to the engine load, Based on the comparison result, the configuration is switched from the use of gas fuel to the use of liquid fuel.
  • the gas fuel is used preferentially. can do.
  • the use of the gas fuel is limited to deteriorate the emission. Can be avoided.
  • the tank main stop valve 44 serving as a shutoff control valve.
  • the liquid fuel injection is switched to the gas fuel injection while the shutoff valve 45 is closed.
  • the shutoff control valve After switching from gas fuel injection to liquid fuel injection, when the supply gas pressure (injection pressure) to the first injection valve 21 further increases and exceeds the determination value K2, the shutoff control valve is closed. In this state, the liquid fuel injection is switched to the gas fuel injection. If the supply gas pressure to the first injection valve 21 becomes excessively high, the first injection valve 21 may not be opened due to the high pressure state. Considering this point, by adopting the above-described configuration, it is possible to prevent the inconvenience that the first injection valve 21 cannot be opened.
  • the operation state is changed to promote the consumption of gas fuel.
  • the intake air amount of the engine 10 is increased and corrected according to the engine load so that “required fuel amount Qa> minimum fuel amount Qmin”, and the ignition timing is corrected to the retard side.
  • the gas fuel is consumed by the combustion of the engine 10, whereby the high pressure state of the low pressure passage portion can be eliminated.
  • the ignition timing retardation correction is also performed, it is possible to prevent an increase in torque even when the intake air amount increase correction is performed.
  • the tank main stop is performed when the injection pressure falls below the determination value K3 after switching to the injection of gas fuel by the first injection valve 21.
  • the valve 44 and the shutoff valve 45 are configured to open. Thereby, it can avoid that supply gas pressure falls too much.
  • the determination value K3 is determined to be lower than the set pressure Preg, the flow rate of the gas passing through the valve seat 63 can be increased when the tank main stop valve 44 and the shutoff valve 45 are switched to the open state. By the large flow rate, it is possible to easily remove foreign matters adhering to the valve seat portion 63.
  • the determination value K2 is set to be lower than the relief pressure Pref and the operation limit pressure Plim, the first injection valve is before the relief valve 69 is opened (before the gas fuel is released into the atmosphere).
  • the high pressure state of the low pressure passage portion can be relaxed before the valve 21 cannot be opened.
  • the said 1st Embodiment In the said 1st Embodiment, it was set as the structure which switches to the injection of the gas fuel by the 1st injection valve 21, and reduces an injection pressure on condition that the injection pressure exceeded determination value K2.
  • the first fuel injection by the first injection valve 21 On the condition that the injection pressure exceeds the determination value K2 and the fuel cut request at the time of deceleration is occurring, the first fuel injection by the first injection valve 21 is performed. It is set as the structure which switches and reduces an injection pressure. By adopting a configuration in which gas fuel is injected in the ignition cut state during fuel cut during deceleration, the injection pressure can be reduced while minimizing the influence on drivability.
  • the injection pressure and the minimum fuel amount Qmin are in a proportional relationship, and the higher the injection pressure, the larger the minimum fuel amount Qmin that can be injected per time.
  • each cylinder has a predetermined phase (if it is a three-cylinder engine) as in normal operation. If fuel injection is performed (with an injection cycle of 240 ° C. A), it is conceivable that fuel will be excessive. In such a case, the emission may be deteriorated or the catalyst temperature may be excessively increased.
  • the first injection cycle is made longer than one combustion cycle of each cylinder. The injection of gas fuel by the injection valve 21 is performed.
  • FIG. 9 is a time chart showing a specific aspect of the fuel injection control of the present embodiment.
  • the tank main stop valve 44 is closed at the timing t31, and then the shutoff valve 45 is closed.
  • the minimum fuel amount Qmin is larger than the required fuel amount Qa in the first injection valve 21
  • the gas fuel injection from the first injection valve 21 is changed to the liquid fuel injection by the second injection valve 22. Switch.
  • the gas fuel is injected only in a specific cylinder among the three cylinders, and the gas fuel is not injected in the other cylinders.
  • the injection pressure is reduced by the injection of the gas fuel, and the increase correction of the intake air amount is canceled at timing t35 when “injection pressure ⁇ determination value K3”.
  • steps S200 to S208 are the same as steps S100 to S108 in FIG. If it is determined in step S208 that “injection pressure> determination value K2”, the process proceeds to step S209, and it is determined whether or not a fuel cut condition during deceleration is satisfied (condition determination means).
  • the fuel cut condition at the time of deceleration includes that the amount of accelerator operation by the driver is zero, the engine rotation speed is a predetermined value or more, and the like.
  • the process proceeds to step S210, and it is determined whether or not the catalyst temperature is within a predetermined range.
  • the catalyst temperature may be estimated based on a detection value of a temperature sensor that detects the exhaust gas temperature, or the detection value may be used when a sensor that detects the catalyst temperature is provided.
  • step S211 If the catalyst temperature is not within the predetermined range, the process proceeds to step S211, and fuel injection and ignition are prohibited. On the other hand, if the catalyst temperature is within the predetermined range, the process proceeds to step S212, the ignition cut is performed, and the intake air amount is increased and corrected in step S213. Further, in step S214, the gas fuel is intermittently injected by the first injection valve 21. The injection pressure is reduced by the intermittent injection of the gas fuel.
  • steps S215 and S216 the processing in steps S111 and S112 in FIG. 5 is executed, and it is determined in step S217 whether or not the fuel is being cut during deceleration. The process proceeds to step S218 on condition that the fuel cut at the time of deceleration is not being performed, the same processing as steps S113 and S114 in FIG. 5 is executed, and this processing is terminated.
  • the injection pressure exceeds the determination value K2
  • the injection pressure is reduced by switching to gas fuel injection by the first injection valve 21 during the fuel cut period during deceleration.
  • the injection pressure can be reduced to the set pressure Preg while minimizing the influence on drivability.
  • injection pressure> decision value K2 when switching to gas fuel injection by the first injection valve 21 during the fuel cut period during deceleration, the injection cycle is made longer than one combustion cycle of each cylinder.
  • the first fuel injection valve 21 is configured to inject gas fuel. During fuel cut during deceleration, there is a limit to the amount of intake air that can be increased. Therefore, if fuel injection is performed for each predetermined phase in each cylinder as in normal operation, there is a risk of excessive fuel. According to this configuration, it is possible to prevent the deterioration of the emission and the excessive increase in the catalyst temperature when the injection pressure is reduced by the injection of the gas fuel.
  • the tank main stop valve 44 and the cutoff valve 45 as the cutoff control valves are closed.
  • the intake air amount is corrected to increase in accordance with the engine load at that time, and the injection amount of gas fuel from the first injection valve 21 is corrected to increase to increase the engine speed.
  • the use of gas fuel can be continued even when the supply gas pressure to the first injection valve 21 exceeds the determination value K1.
  • it is not necessary to switch to the injection of the liquid fuel by the second injection valve 22 it is possible to cope with the increase in the supply gas pressure even when the remaining amount of the liquid fuel is small.
  • FIG. 11 is a time chart showing a specific aspect of the fuel injection control of the present embodiment.
  • a foreign matter is caught in the valve seat 63 of the pressure regulating valve 60 and the injection pressure exceeds the determination value K1 in an idle operation state using gas fuel. Since the engine is in operation, the tank main stop valve 44 and the shutoff valve 45 are open before the injection pressure exceeds the determination value K1.
  • the tank main stop valve 44 is closed at the timing t41, and then the shutoff valve 45 is closed. Further, the amount of intake air and the required fuel amount Qa of the first injection valve 21 are set so as to become the minimum fuel amount Qmin determined according to the supply gas pressure (injection pressure) to the first injection valve 21 or higher. The fuel injection amount is corrected to increase. At this time, the intake air amount is corrected so that the air-fuel ratio becomes the stoichiometric air-fuel ratio or leaner than that. Thereby, the engine rotation speed becomes higher than the idle rotation speed NE1 (for example, 700 rpm), and the operation of the engine 10 is continued in this state. At this time, since the tank main stop valve 44 and the shutoff valve 45 remain closed, the injection pressure is reduced by the injection of gas fuel from the first injection valve 21.
  • the idle rotation speed NE1 for example, 700 rpm
  • the shutoff valve 45 is opened, and then the tank main stop valve 44 is opened. Further, after the injection pressure is adjusted to the set pressure Preg as the valves 44 and 45 are opened, the increase correction of the intake air amount is cancelled.
  • the gas fuel supply pressure injection pressure
  • injection pressure increases unintentionally.
  • the shutoff control valve is closed and the consumption of the gas fuel injected from the first injection valve 21 according to the operating load of the internal combustion engine. Therefore, it is possible to suppress the excessive amount of injected fuel.
  • the use of gas fuel can be continued even when the supply gas pressure to the first injection valve 21 exceeds the determination value K1. Furthermore, since it is not necessary to switch to the injection of the liquid fuel by the second injection valve 22, it is possible to cope with the increase in the injection pressure even when the remaining amount of the liquid fuel is small.
  • the tank main stop valve 44 and the cutoff valve 45 are provided as the cutoff control valves, and when the injection pressure exceeds the determination value K1, the tank main stop valve 44 and the cutoff valve 45 are closed. However, only one of them may be controlled. For example, in the configuration shown in FIG. 1, when the injection pressure exceeds the determination value K1, only the shutoff valve 45 is closed and the tank main stop valve 44 is left open. Also in this case, since the supply of gas fuel from the gas tank 42 to the first injection valve 21 can be cut off, the same effects as described above are obtained.
  • the shut-off control valve is closed and the gas fuel by the first injection valve 21 is changed according to the engine load. It was set as the structure which restrict
  • the supply gas pressure to the 1st injection valve 21 exceeds determination value K1
  • the process of restricting the injection of gas fuel by (1) and (2) the process of changing to the operating state that promotes the consumption of the gas fuel injected from the first injection valve 21 according to the engine load is performed. To select (process selection means). If the process (1) is selected, the same processes as in steps S104 to S107 in FIG. 5 are executed.
  • the intake air amount is increased and corrected in accordance with the engine load at that time, and the gas fuel amount injected from the first injection valve 21 is increased and corrected. Execute the process to raise.
  • the process selection means is selected based on, for example, the remaining amount of liquid fuel. If the remaining amount of liquid fuel is equal to or greater than a predetermined value, the process (1) is selected, and the remaining amount is determined to be predetermined. When the value is lower than the value, the process (2) may be selected.
  • the regulator 43 It is good also as a structure which determines that it is abnormal. Moreover, it is good also as a structure which notifies a driver
  • a retreat travel process for controlling the injection pressure by controlling the drive of the shutoff control valves may be performed.
  • the injection pressure is controlled by the cutoff valve 45 on the downstream side by controlling the injection pressure by the cutoff control valve arranged at the upstream side of the fuel pipe, that is, the tank main stop valve 44, the first injection valve.
  • the volume of the fuel pipe up to 21 can be increased, and the fluctuation of the injection pressure caused by opening and closing of the valve can be suppressed. Thereby, injection pressure can be controlled stably.
  • step S112 of FIG. 5 the supply gas pressure to the first injection valve 21 is compared with the determination value K3, and when the supply gas pressure falls below the determination value K3, the shutoff valve 45 and the tank main stop as the shutoff control valve.
  • the valve 44 is driven to open.
  • a configuration using the set pressure Preg may be used.
  • the determination value K1 to the determination value K3 are constant values.
  • the determination value K1 to the determination value K3 are variable according to at least one of battery voltage, engine cooling water temperature, intake air temperature, regulator upstream pressure, gas fuel temperature, and the like. Also good.
  • first injection valves 21 and the second injection valves 22 are provided for each cylinder of the multi-cylinder engine.
  • first injection valve 21 and the second injection valve are provided in common portions of the plurality of cylinders. It is good also as a structure which provides at least any one of 22. For example, it is good also as a structure which injects gaseous fuel and liquid fuel with respect to the collection part of the intake system 11. FIG.
  • the gas fuel is CNG fuel, but other gas fuels in a gas state can be used in the standard state.
  • the liquid fuel is not limited to gasoline fuel, and for example, light oil or the like may be used.

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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
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  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

This fuel injection system is provided with: first injection valves (21) that inject a fuel gas; a pressure-adjusting valve (60) that reduces the pressure of the fuel gas, which is supplied to the first injection valves (21), to a preset pressure; and a main tank stop valve (44) and a cutoff valve (45), which are disposed on the upstream side of the pressure-adjusting valve (60). If the supply pressure to the injection valves (21) exceeds a determination value (K1), a control unit (80) closes the cutoff control valves (44, 45), and switches to injection of a liquid fuel by second injection valves (22) from injection of the fuel gas by the first injection valves (21) in response to an engine load.

Description

内燃機関の燃料噴射制御装置Fuel injection control device for internal combustion engine 関連出願の相互参照Cross-reference of related applications
　本開示は、２０１２年１２月１３日に出願された日本出願番号２０１２－２７２８３３に基づくもので、ここにその記載内容を援用する。 This disclosure is based on Japanese Application No. 2012-272833 filed on Dec. 13, 2012, the description of which is incorporated herein.
　本開示は、内燃機関の燃料噴射制御装置に関し、詳しくはガス燃料及び液体燃料をそれぞれ供給可能な燃料供給系を備える車載内燃機関の燃料噴射制御装置に関する。 The present disclosure relates to a fuel injection control device for an internal combustion engine, and more particularly to a fuel injection control device for an in-vehicle internal combustion engine including a fuel supply system capable of supplying gas fuel and liquid fuel, respectively.
　圧縮天然ガス（ＣＮＧ）等のガス燃料を燃焼させるようにした内燃機関が知られている。こうした内燃機関において、ガス燃料を燃料噴射弁に供給する燃料供給系の構成として、ガス燃料を高圧状態で貯蔵するガスタンクと、ガスタンクと燃料噴射手段とを繋ぐ燃料配管の途中に設けられ、ガスタンクから供給されるガス燃料の圧力を減圧調整する圧力調整弁と、圧力調整弁よりも上流側（ガスタンク側）に設けられ、圧力調整弁に対するガス燃料の流通を遮断する遮断弁と、を備える構成が知られている（例えば特許文献１参照）。 There is known an internal combustion engine in which gas fuel such as compressed natural gas (CNG) is burned. In such an internal combustion engine, a fuel supply system that supplies gas fuel to a fuel injection valve is provided in the middle of a fuel tank that connects the gas tank and the fuel injection means, and a gas tank that stores the gas fuel in a high pressure state. A pressure regulating valve that depressurizes and adjusts the pressure of the supplied gas fuel, and a shutoff valve that is provided upstream of the pressure regulating valve (on the gas tank side) and blocks the flow of the gas fuel to the pressure regulating valve. It is known (see, for example, Patent Document 1).
　この特許文献１には、圧力調整弁が作動不良となり、燃料噴射弁に供給されるガス燃料の圧力が所定値を超えた場合、遮断弁を閉弁することによって圧力調整弁よりも下流側へのガス燃料の供給を遮断するとともに、燃料噴射弁からガス燃料を噴射することが開示されている。また、遮断弁を閉弁した状態でのガス燃料の噴射により、燃料噴射弁に供給されるガス燃料の圧力が所定値よりも低くなった場合には、遮断弁を開弁して、圧力調整弁から下流側へのガス燃料の供給を行うことが開示されている。 In Patent Document 1, when the pressure regulating valve malfunctions and the pressure of the gas fuel supplied to the fuel injection valve exceeds a predetermined value, the shutoff valve is closed to the downstream side of the pressure regulating valve. The gas fuel supply is shut off and the fuel gas is injected from the fuel injection valve. If the pressure of the gas fuel supplied to the fuel injection valve becomes lower than a predetermined value due to the injection of gas fuel with the shut-off valve closed, the shut-off valve is opened to adjust the pressure. It is disclosed that gas fuel is supplied downstream from the valve.
特許第３６７５２１３号公報Japanese Patent No. 3675213
　ガス燃料の密度（ガス密度）は燃料圧力に応じて相違する。そのため、燃料噴射弁に対するガス燃料の供給圧力（噴射圧）によっては、遮断弁を閉弁した状態でのガス燃料の噴射を実施することにより、噴射燃料が過多になることが考えられる。 Gas fuel density (gas density) varies depending on fuel pressure. Therefore, depending on the supply pressure (injection pressure) of the gas fuel to the fuel injection valve, it is conceivable that the injection fuel becomes excessive by injecting the gas fuel with the shut-off valve closed.
　本開示では、ガス燃料と液体燃料とを切り替えて使用する内燃機関の燃料噴射システムにおいて、噴射圧が設定圧力より高圧状態となった場合にも適切な燃料噴射制御を実施することができる内燃機関の燃料噴射制御装置を提供することを主たる目的とする。 In the present disclosure, in a fuel injection system of an internal combustion engine that switches between gas fuel and liquid fuel, an internal combustion engine capable of performing appropriate fuel injection control even when the injection pressure is higher than a set pressure. The main object of the present invention is to provide a fuel injection control device.
　本開示は、ガス燃料を噴射する第１噴射手段と、液体燃料を噴射する第２噴射手段と、前記ガス燃料を供給する燃料通路に設けられ、前記第１噴射手段に供給されるガス燃料の圧力を所定の設定圧力に減圧調整する圧力調整弁と、前記燃料通路において前記圧力調整弁の上流側に設けられ、前記ガス燃料の流通を遮断する遮断機能を有する遮断制御弁と、を備える燃料噴射システムに適用され、前記第１噴射手段によるガス燃料の噴射と前記第２噴射手段による液体燃料の噴射とを切り替えて実施する内燃機関の燃料噴射制御装置に関する。 The present disclosure includes a first injection unit that injects gas fuel, a second injection unit that injects liquid fuel, a fuel passage that supplies the gas fuel, and a gas fuel that is supplied to the first injection unit. A fuel comprising: a pressure regulating valve that adjusts the pressure to a predetermined set pressure; and a shut-off control valve that is provided upstream of the pressure regulating valve in the fuel passage and has a shut-off function that shuts off the flow of the gas fuel. The present invention relates to a fuel injection control device for an internal combustion engine that is applied to an injection system and performs switching between injection of gas fuel by a first injection means and injection of liquid fuel by a second injection means.
　更に、燃料噴射制御装置は、前記第１噴射手段に供給されるガス燃料の圧力である供給圧力が、前記設定圧力よりも高圧側の所定の第１判定値を超えたことを判定する第１判定手段と、前記第１判定手段により前記供給圧力が前記第１判定値を超えたことが判定された場合に、前記遮断制御弁を閉弁するとともに、前記内燃機関の運転負荷に応じて前記第１噴射手段によるガス燃料の噴射から前記第２噴射手段による液体燃料の噴射への切り替えを実施する燃料切替手段と、を備える。 Further, the fuel injection control device determines whether the supply pressure, which is the pressure of the gas fuel supplied to the first injection means, has exceeded a predetermined first determination value on the higher pressure side than the set pressure. When the determination means and the first determination means determine that the supply pressure exceeds the first determination value, the shut-off control valve is closed and the internal combustion engine is operated according to the operating load. Fuel switching means for switching from injection of gas fuel by the first injection means to injection of liquid fuel by the second injection means.
　圧力調整弁では、閉弁状態において例えば異物等の噛み込みが生じることによって上流側から下流側へガス燃料がリークし、その燃料リークによって、下流側の燃料圧力、すなわち第１噴射手段へのガス燃料の供給圧力（噴射圧）が意図せずに高くなることが考えられる。また、噴射圧とガス密度とは比例関係にあり、噴射圧が高いほどガス密度が高くなる。そのため、噴射圧が高いと、その高圧状態に起因して、内燃機関の低負荷状態において噴射燃料が過多になることが生じ得る。本構成では、噴射圧が所定値よりも高い高圧状態となった場合には、遮断制御弁を閉弁するとともに、内燃機関の運転負荷に応じてガス燃料の使用を制限して液体燃料の使用に切り替えるため、噴射燃料が過多になることを回避することができる。よって、上記構成によれば、噴射圧が設定圧力より高圧状態となった場合にも、適切な燃料噴射制御を実施することができる。 In the pressure regulating valve, gas fuel leaks from the upstream side to the downstream side when, for example, foreign matter or the like is caught in the closed state, and the fuel pressure on the downstream side, that is, the gas to the first injection means is caused by the fuel leak. It is conceivable that the fuel supply pressure (injection pressure) increases unintentionally. The injection pressure and the gas density are in a proportional relationship, and the gas density increases as the injection pressure increases. Therefore, when the injection pressure is high, the injected fuel may become excessive in a low load state of the internal combustion engine due to the high pressure state. In this configuration, when the injection pressure becomes higher than a predetermined value, the shutoff control valve is closed and the use of liquid fuel is restricted by limiting the use of gas fuel according to the operating load of the internal combustion engine. Therefore, it is possible to avoid excessive injection fuel. Therefore, according to the above configuration, appropriate fuel injection control can be performed even when the injection pressure is higher than the set pressure.
図１は、エンジンの燃料噴射システムの概略を示す構成図。FIG. 1 is a configuration diagram showing an outline of an engine fuel injection system. 図２は、第１噴射弁の概略構成を示す図。FIG. 2 is a diagram showing a schematic configuration of the first injection valve. 図３は、レギュレータの概略構成を示す図。FIG. 3 is a diagram illustrating a schematic configuration of a regulator. 図４は、第１噴射弁への供給ガス圧と燃料の使用領域との関係を示す図。FIG. 4 is a diagram showing a relationship between a supply gas pressure to the first injection valve and a fuel use region. 図５は、第１実施形態における燃料噴射処理の手順を示すフローチャート。FIG. 5 is a flowchart showing a procedure of fuel injection processing in the first embodiment. 図６は、噴射圧と最小燃料量Ｑｍｉｎとの関係を示す図。FIG. 6 is a diagram showing the relationship between the injection pressure and the minimum fuel amount Qmin. 図７は、第１実施形態の燃料噴射処理の具体的態様を示すタイムチャート。FIG. 7 is a time chart showing a specific aspect of the fuel injection processing of the first embodiment. 図８は、第１実施形態の燃料噴射処理の具体的態様を示すタイムチャート。FIG. 8 is a time chart showing a specific aspect of the fuel injection processing of the first embodiment. 図９は、第２実施形態の燃料噴射処理の具体的態様を示すタイムチャート。FIG. 9 is a time chart showing a specific aspect of the fuel injection process of the second embodiment. 図１０は、第２実施形態における燃料噴射処理の手順を示すフローチャート。FIG. 10 is a flowchart showing a procedure of fuel injection processing in the second embodiment. 図１１は、第３実施形態の燃料噴射処理の具体的態様を示すタイムチャート。FIG. 11 is a time chart showing a specific aspect of the fuel injection process of the third embodiment.
　（第１実施形態）
　以下、本開示の第１実施形態を、図面を参照しつつ説明する。本実施形態は、ガス燃料である圧縮天然ガス（ＣＮＧ）と液体燃料であるガソリンとを燃焼用の燃料として使用する、いわゆるバイフューエルタイプの車載多気筒エンジン（多気筒内燃機関）に適用される燃料噴射システムとして具体化するものとしている。本システムの全体概略図を図１に示す。 (First embodiment)
Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. The present embodiment is applied to a so-called bi-fuel type on-vehicle multi-cylinder engine (multi-cylinder internal combustion engine) that uses compressed natural gas (CNG) as a gas fuel and gasoline as a liquid fuel as combustion fuel. It is supposed to be embodied as a fuel injection system. An overall schematic diagram of this system is shown in FIG.
　図１に示すエンジン１０は直列３気筒の火花点火式エンジンよりなり、その吸気ポート及び排気ポートには吸気系統１１、排気系統１２がそれぞれ接続されている。吸気系統１１は、吸気マニホールド１３と吸気管１４とを有している。吸気マニホールド１３は、エンジン１０の吸気ポートに接続される複数（エンジン１０の気筒数分）の分岐管部１３ａと、その上流側であって吸気管１４に接続される集合部１３ｂとを有している。吸気管１４には空気量調整手段としてのスロットル弁１５が設けられている。このスロットル弁１５は、ＤＣモータ等のスロットルアクチュエータ１５ａにより開度調節される電子制御式のスロットル弁として構成されている。スロットル弁１５の開度（スロットル開度）は、スロットルアクチュエータ１５ａに内蔵されたスロットル開度センサ１５ｂにより検出されるようになっている。 1 is an inline three-cylinder spark ignition engine, and an intake system 11 and an exhaust system 12 are connected to an intake port and an exhaust port, respectively. The intake system 11 has an intake manifold 13 and an intake pipe 14. The intake manifold 13 has a plurality of (for the number of cylinders of the engine 10) branch pipe portions 13a connected to the intake port of the engine 10, and a collective portion 13b connected to the intake pipe 14 on the upstream side. ing. The intake pipe 14 is provided with a throttle valve 15 as air amount adjusting means. The throttle valve 15 is configured as an electronically controlled throttle valve whose opening degree is adjusted by a throttle actuator 15a such as a DC motor. The opening degree of the throttle valve 15 (throttle opening degree) is detected by a throttle opening degree sensor 15b incorporated in the throttle actuator 15a.
　また、排気系統１２は、排気マニホールド１６と排気管１７とを有している。排気マニホールド１６は、エンジン１０の排気ポートに接続される複数（エンジン１０の気筒数分）の分岐管部１６ａと、その下流側であって排気管１７に接続される集合部１６ｂとを有している。排気管１７には、排気の成分を検出する排気センサ１８と、排気を浄化する触媒１９とが設けられている。排気センサ１８としては、排気中の酸素濃度から空燃比を検出する空燃比センサが設けられている。 Further, the exhaust system 12 has an exhaust manifold 16 and an exhaust pipe 17. The exhaust manifold 16 has a plurality of (for the number of cylinders of the engine 10) branch pipe portions 16a connected to the exhaust port of the engine 10 and a collecting portion 16b connected to the exhaust pipe 17 on the downstream side. ing. The exhaust pipe 17 is provided with an exhaust sensor 18 for detecting exhaust components and a catalyst 19 for purifying exhaust. As the exhaust sensor 18, an air-fuel ratio sensor that detects the air-fuel ratio from the oxygen concentration in the exhaust gas is provided.
　エンジン１０の各気筒には点火プラグ２０が設けられている。点火プラグ２０には、点火コイル等よりなる点火装置２０ａを通じて、所望とする点火時期に高電圧が印加される。この高電圧の印加により、各点火プラグ２０の対向電極間に火花放電が発生し、気筒内（燃焼室内）に導入した燃料が着火され燃焼に供される。 A spark plug 20 is provided in each cylinder of the engine 10. A high voltage is applied to the ignition plug 20 at a desired ignition timing through an ignition device 20a including an ignition coil. By applying this high voltage, a spark discharge is generated between the opposing electrodes of each spark plug 20, and the fuel introduced into the cylinder (combustion chamber) is ignited and used for combustion.
　また、本システムは、エンジン１０に対して燃料を噴射供給する燃料噴射手段として、ガス燃料（ＣＮＧ燃料）を噴射する第１噴射弁２１と、液体燃料（ガソリン）を噴射する第２噴射弁２２とを有している。これら各噴射弁２１，２２は、吸気系統１１において吸気マニホールド１３の分岐管部１３ａにそれぞれ燃料を噴射するものであり、第１噴射弁２１の噴射によりガス燃料が各気筒の吸気ポートに供給され、第２噴射弁２２の噴射により液体燃料が各気筒の吸気ポートに供給される。 Further, the present system is a fuel injection means for injecting and supplying fuel to the engine 10, a first injection valve 21 for injecting gas fuel (CNG fuel), and a second injection valve 22 for injecting liquid fuel (gasoline). And have. Each of these injection valves 21 and 22 injects fuel into the branch pipe portion 13a of the intake manifold 13 in the intake system 11, and gas fuel is supplied to the intake port of each cylinder by the injection of the first injection valve 21. The liquid fuel is supplied to the intake port of each cylinder by the injection of the second injection valve 22.
　各噴射弁２１，２２は、電磁駆動部が電気的に駆動されることで弁体が閉位置から開位置にリフトされる開閉タイプの制御弁であり、制御部８０から入力されるオン／オフ式の開弁駆動信号によりそれぞれ開弁駆動される。これら各噴射弁２１，２２は、通電により開弁し、通電遮断により閉弁する。そして、通電時間に応じた量の燃料（ガス燃料、液体燃料）が各噴射弁２１，２２から噴射される。なお、本実施形態では、第１噴射弁２１の先端部に噴射管２３が接続されており、第１噴射弁２１から噴出されたガス燃料は噴射管２３を介して吸気マニホールド１３の分岐管部１３ａに噴射されるようになっている。 Each of the injection valves 21 and 22 is an open / close type control valve in which the valve body is lifted from the closed position to the open position by electrically driving the electromagnetic drive unit. Each valve is driven to open by a valve opening drive signal. These injection valves 21 and 22 are opened by energization and closed by energization interruption. An amount of fuel (gas fuel, liquid fuel) corresponding to the energization time is injected from each of the injection valves 21 and 22. In this embodiment, the injection pipe 23 is connected to the tip of the first injection valve 21, and the gas fuel injected from the first injection valve 21 is branched through the injection pipe 23. 13a is injected.
　ここで、ガス噴射用の第１噴射弁２１の構成を、図２を参照して説明する。図２（ａ）は非噴射状態を示し、図２（ｂ）は噴射状態を示している。第１噴射弁２１は、自身に供給されるガス燃料の圧力により閉鎖シール性が高められる、セルフシール構造を有している。 Here, the configuration of the first injection valve 21 for gas injection will be described with reference to FIG. FIG. 2A shows a non-injection state, and FIG. 2B shows an injection state. The first injection valve 21 has a self-sealing structure in which the closing sealing performance is enhanced by the pressure of the gas fuel supplied to itself.
　第１噴射弁２１は筒状のボディ３１を有している。ボディ３１には弁体３２が摺動可能に収容されており、そのボディ３１内において弁体３２がばね３３により閉弁方向に付勢されている。図２（ａ）では、弁体３２の先端部によって、噴射弁先端に設けられた噴孔部３４が閉鎖されている。また、ボディ３１内には、弁体３２の後端側（上流側）に第１燃料室３５が設けられているとともに、弁体３２の先端側（下流側）に第２燃料室３６が設けられている。弁体３２には、摺動部分よりも先端側に小径部３２ａが設けられており、その小径部３２ａの周りに第２燃料室３６が設けられている。第１燃料室３５と第２燃料室３６とは、弁体３２に設けられた燃料通路３７を介して連通されており、燃料通路３７の入口側は第１燃料室３５に通じ、出口側は第２燃料室３６に通じている。弁体３２は、ソレノイド等からなる電磁駆動部３８への通電に応じて開弁位置に変位する。 The first injection valve 21 has a cylindrical body 31. A valve body 32 is slidably accommodated in the body 31, and the valve body 32 is biased in the valve closing direction by a spring 33 in the body 31. In FIG. 2A, the nozzle hole 34 provided at the tip of the injection valve is closed by the tip of the valve body 32. In the body 31, a first fuel chamber 35 is provided on the rear end side (upstream side) of the valve body 32, and a second fuel chamber 36 is provided on the front end side (downstream side) of the valve body 32. It has been. The valve body 32 is provided with a small-diameter portion 32a on the tip side of the sliding portion, and a second fuel chamber 36 is provided around the small-diameter portion 32a. The first fuel chamber 35 and the second fuel chamber 36 are in communication with each other via a fuel passage 37 provided in the valve body 32. The inlet side of the fuel passage 37 communicates with the first fuel chamber 35, and the outlet side thereof It leads to the second fuel chamber 36. The valve body 32 is displaced to the valve opening position in response to energization to the electromagnetic drive unit 38 composed of a solenoid or the like.
　上記構成の第１噴射弁２１では、第１燃料室３５に対して後述のレギュレータ４３からガス燃料が供給され、そのガス燃料が燃料通路３７を介して第２燃料室３６にも導入される。図２（ｂ）に示すように、電磁駆動部３８への通電に伴いばね３３の付勢力に抗して弁体３２が開弁位置に変位すると、噴孔部３４が開放され、ガス燃料が噴射される。 In the first injection valve 21 configured as described above, gas fuel is supplied from a regulator 43 described later to the first fuel chamber 35, and the gas fuel is also introduced into the second fuel chamber 36 through the fuel passage 37. As shown in FIG. 2 (b), when the valve element 32 is displaced to the valve opening position against the urging force of the spring 33 as the electromagnetic drive unit 38 is energized, the nozzle hole 34 is opened, and the gas fuel is discharged. Be injected.
　第１噴射弁２１において、弁体３２にはその先端側に小径部３２ａが設けられていることから、閉弁状態での第１燃料室３５側の受圧面積と第２燃料室３６側の受圧面積の関係は、「第１燃料室３５側の受圧面積＞第２燃料室３６側の受圧面積」となっている（図２（ａ）参照）。そのため、図２（ａ）に示す閉弁状態では、レギュレータ４３側から供給されるガス燃料の圧力（噴射圧に相当）が、弁体３２を閉弁する方向（閉弁方向）に対してはより大きく作用するようになっている。なお、図２（ｂ）に示す開弁状態では、小径部３２ａの端面（図の下端面）にも噴射圧が作用するため、弁体３２に作用する閉弁方向の燃料圧力と開弁方向の燃料圧力とは略同じになっている。 In the first injection valve 21, the valve body 32 is provided with a small-diameter portion 32 a on the distal end side thereof, so that the pressure receiving area on the first fuel chamber 35 side and the pressure receiving side on the second fuel chamber 36 side in the valve-closed state. The relationship of the areas is “pressure receiving area on the first fuel chamber 35 side> pressure receiving area on the second fuel chamber 36 side” (see FIG. 2A). Therefore, in the valve closing state shown in FIG. 2A, the pressure of the gas fuel supplied from the regulator 43 side (corresponding to the injection pressure) is in the direction in which the valve body 32 is closed (valve closing direction). It comes to act more greatly. 2B, the injection pressure also acts on the end face (the lower end face in the figure) of the small-diameter portion 32a, so that the fuel pressure in the valve closing direction acting on the valve body 32 and the valve opening direction are also applied. The fuel pressure is almost the same.
　図１の説明に戻り、次に、第１噴射弁２１に対してガス燃料を供給するガス燃料供給部４０の構成と、第２噴射弁２２に対して液体燃料を供給する液体燃料供給部７０の構成とを説明する。 Returning to the description of FIG. 1, the configuration of the gas fuel supply unit 40 that supplies the gas fuel to the first injection valve 21 and the liquid fuel supply unit 70 that supplies the liquid fuel to the second injection valve 22. Will be described.
　ガス燃料供給部４０において、第１噴射弁２１にはガス配管４１を介してガスタンク４２が接続されており、そのガス配管４１の途中には、第１噴射弁２１に供給されるガス燃料の圧力を減圧調整する圧力調整機能を有するレギュレータ４３が設けられている。レギュレータ４３（圧力調整弁６０）は、ガスタンク４２内に貯蔵された高圧状態（例えば最大２０ＭＰａ）のガス燃料が、第１噴射弁２１の噴射圧である所定の設定圧（例えば０．２～１．０ＭＰａの範囲内の一定圧、本実施形態では０．３±α（ＭＰａ））になるように減圧調整するものである。また、減圧調整後のガス燃料は、ガス配管４１を通って第１噴射弁２１に供給されるようになっている。なお、ガス配管４１において、レギュレータ４３よりも上流側が高圧側通路を形成する高圧配管部４１ａ、下流側が低圧側通路を形成する低圧配管部４１ｂとなっている。 In the gas fuel supply unit 40, a gas tank 42 is connected to the first injection valve 21 via a gas pipe 41, and the pressure of the gas fuel supplied to the first injection valve 21 is in the middle of the gas pipe 41. There is provided a regulator 43 having a pressure adjusting function for adjusting the pressure under pressure. The regulator 43 (the pressure adjusting valve 60) is configured such that a gas fuel in a high pressure state (for example, a maximum of 20 MPa) stored in the gas tank 42 is a predetermined set pressure (for example, 0.2 to 1) that is the injection pressure of the first injection valve 21. The pressure is adjusted to a constant pressure within a range of 0.0 MPa, in this embodiment, 0.3 ± α (MPa). In addition, the gas fuel after the decompression adjustment is supplied to the first injection valve 21 through the gas pipe 41. In the gas pipe 41, the upstream side of the regulator 43 is a high-pressure pipe portion 41a that forms a high-pressure side passage, and the downstream side is a low-pressure pipe portion 41b that forms a low-pressure side passage.
　ガス配管４１等により形成されるガス燃料通路には更に、ガスタンク４２の燃料出口の付近に配置されたタンク主止弁４４（タンク出口弁）と、そのタンク主止弁４４よりも下流側であってレギュレータ４３の燃料入口の付近に配置された遮断弁４５とが設けられており、これら各弁４４，４５によって、ガス配管４１におけるガス燃料の流通が許容及び遮断されるようになっている。タンク主止弁４４及び遮断弁４５はいずれも電磁式の開閉弁であり、非通電時においてガス燃料の流通が遮断され、通電時においてガス燃料の流通が許容される常閉式となっている。なお、タンク主止弁４４及び遮断弁４５が、「遮断制御弁」に相当する。 The gas fuel passage formed by the gas pipe 41 and the like further includes a tank main stop valve 44 (tank outlet valve) disposed in the vicinity of the fuel outlet of the gas tank 42 and a downstream side of the tank main stop valve 44. In addition, a shutoff valve 45 disposed near the fuel inlet of the regulator 43 is provided, and the flow of gas fuel in the gas pipe 41 is allowed and shut off by these valves 44 and 45. Both the tank main stop valve 44 and the shut-off valve 45 are electromagnetic on-off valves, and are normally closed so that the flow of gas fuel is cut off when not energized and the flow of gas fuel is allowed when energized. The tank main stop valve 44 and the shutoff valve 45 correspond to a “shutoff control valve”.
　ガス配管４１の高圧配管部４１ａには燃料圧力を検出する圧力センサ４６と、燃料温度を検出する温度センサ４７とが設けられ、低圧配管部４１ｂには燃料圧力を検出する圧力センサ４８と、燃料温度を検出する温度センサ４９とが設けられている。遮断弁４５と圧力センサ４６とはレギュレータ４３に一体に設けることが可能であり、本実施形態では、レギュレータ４３に一体に遮断弁４５と圧力センサ４６とを設ける構成を採用することとしている。 A pressure sensor 46 for detecting the fuel pressure and a temperature sensor 47 for detecting the fuel temperature are provided in the high pressure pipe portion 41a of the gas pipe 41, and a pressure sensor 48 for detecting the fuel pressure is provided in the low pressure pipe portion 41b. A temperature sensor 49 for detecting the temperature is provided. The shut-off valve 45 and the pressure sensor 46 can be provided integrally with the regulator 43. In this embodiment, a configuration in which the shut-off valve 45 and the pressure sensor 46 are provided integrally with the regulator 43 is adopted.
　レギュレータ４３の具体的構成を、図３を用いて説明する。レギュレータ４３は、設定圧に対して低圧配管部４１ｂ内の燃料圧力を調整する機械式の圧力調整装置を構成するものである。 A specific configuration of the regulator 43 will be described with reference to FIG. The regulator 43 constitutes a mechanical pressure adjusting device that adjusts the fuel pressure in the low-pressure pipe portion 41b with respect to the set pressure.
　図３に示す様に、レギュレータ４３は、高圧配管部４１ａに接続される高圧通路５１と、低圧配管部４１ｂに接続される低圧通路５２とを有しており、高圧通路５１には遮断弁４５と圧力センサ４６とが設けられている。圧力センサ４６は、遮断弁４５よりも上流側でガス燃料の圧力を検出する。符号５３は、異物除去用のフィルタである。 As shown in FIG. 3, the regulator 43 has a high-pressure passage 51 connected to the high-pressure pipe section 41a and a low-pressure passage 52 connected to the low-pressure pipe section 41b. And a pressure sensor 46 are provided. The pressure sensor 46 detects the pressure of the gas fuel upstream of the shutoff valve 45. Reference numeral 53 is a filter for removing foreign matter.
　遮断弁４５の構成は第１噴射弁２１の構成と概ね同じであり、セルフシール構造を有している。その構成を簡単に説明する。遮断弁４５は、ばね５４により閉弁方向に付勢された弁体５５を有しており、電磁駆動部５６が通電されることによりばね５４の付勢力に抗して弁体５５が閉弁位置から開弁位置に変位するようになっている。弁体５５の後端側（上流側）には第１燃料室５７が設けられるとともに、弁体５５の先端側（小径部が設けられた下流側）には第２燃料室５８が設けられている。これら両燃料室５７，５８は、弁体５５に設けられた燃料通路５９を介して連通されている。この場合、両燃料室５７，５８にはガスタンク４２から高圧のガス燃料が供給され、遮断弁４５の閉鎖状態下ではガスタンク４２側の燃料圧力により弁体５５に閉鎖方向の力が付与されている。そして、電磁駆動部５６への通電に伴いばね５４の付勢力に抗して弁体５５が開弁位置に変位すると（図示の状態）、高圧のガス燃料が下流側に流通する。 The configuration of the shut-off valve 45 is substantially the same as the configuration of the first injection valve 21 and has a self-sealing structure. The configuration will be briefly described. The shut-off valve 45 has a valve body 55 biased in the valve closing direction by a spring 54, and the valve body 55 is closed against the biasing force of the spring 54 by energizing the electromagnetic drive unit 56. The valve is displaced from the position to the valve opening position. A first fuel chamber 57 is provided on the rear end side (upstream side) of the valve body 55, and a second fuel chamber 58 is provided on the distal end side (downstream side where the small diameter portion is provided) of the valve body 55. Yes. Both the fuel chambers 57 and 58 are communicated with each other through a fuel passage 59 provided in the valve body 55. In this case, high-pressure gas fuel is supplied to both the fuel chambers 57 and 58 from the gas tank 42, and in the closed state of the shutoff valve 45, a closing force is applied to the valve body 55 by the fuel pressure on the gas tank 42 side. . When the valve element 55 is displaced to the valve open position against the biasing force of the spring 54 with the energization of the electromagnetic drive unit 56 (as shown), high-pressure gas fuel flows downstream.
　レギュレータ４３において、遮断弁４５の下流側には圧力調整弁６０が設けられている。圧力調整弁６０の構成として、高圧通路５１には弁体室６１が設けられており、その弁体室６１には弁体６２が収容されている。弁体６２は低圧通路５２の入口部分である弁座部６３を開閉する。弁体６２が開位置にあれば、弁座部６３が開かれて高圧通路５１と低圧通路５２とが連通される。また、弁体６２が閉位置にあれば、弁座部６３が閉じられて高圧通路５１と低圧通路５２との連通が遮断される。 In the regulator 43, a pressure regulating valve 60 is provided on the downstream side of the shutoff valve 45. As a configuration of the pressure regulating valve 60, a valve body chamber 61 is provided in the high pressure passage 51, and a valve body 62 is accommodated in the valve body chamber 61. The valve body 62 opens and closes a valve seat portion 63 that is an inlet portion of the low pressure passage 52. If the valve body 62 is in the open position, the valve seat 63 is opened and the high pressure passage 51 and the low pressure passage 52 are communicated. If the valve body 62 is in the closed position, the valve seat 63 is closed and the communication between the high pressure passage 51 and the low pressure passage 52 is blocked.
　弁体６２は、低圧通路５２内の燃料圧力（噴射圧に相当）と、弁体作動部６５により生じる開弁方向の力とに応じて開閉される。弁体作動部６５は、大気に開放された空間であってその内部に調整ばね６６が設けられた大気開放部６７を有するとともに、大気開放部６７と低圧通路５２とを仕切る仕切部材としてのダイアフラム６８を有している。ダイアフラム６８は弁体６２に一体に設けられている。ダイアフラム６８には、閉弁方向の力として低圧通路５２内の燃料圧力が作用し、開弁方向の力として調整ばね６６の付勢力と大気圧とが作用する。 The valve body 62 is opened and closed according to the fuel pressure (corresponding to the injection pressure) in the low-pressure passage 52 and the force in the valve opening direction generated by the valve body operating portion 65. The valve element actuating portion 65 is a space that is open to the atmosphere, and has an air opening portion 67 in which an adjustment spring 66 is provided, and a diaphragm as a partition member that partitions the air release portion 67 and the low-pressure passage 52. 68. The diaphragm 68 is provided integrally with the valve body 62. Fuel pressure in the low pressure passage 52 acts on the diaphragm 68 as a force in the valve closing direction, and an urging force of the adjustment spring 66 and atmospheric pressure act as a force in the valve opening direction.
　かかる構成において、「閉弁方向の力＞開弁方向の力」になっていれば、弁体６２が閉弁位置で保持される。一方、第１噴射弁２１の燃料噴射等により低圧通路５２内の燃料圧力が低下し、「閉弁方向の力＜開弁方向の力」になると、ダイアフラム６８の変位に伴い弁体６２が開弁される。このとき、閉弁方向の力と開弁方向の力との差に応じて弁体６２の開位置（弁体リフト量）が決まり、その開位置に応じて弁座部６３における開口面積が変更される。また、この開口面積の変更により、高圧通路５１から低圧通路５２に流入する燃料量が調整される。 In such a configuration, if “force in the valve closing direction> force in the valve opening direction” is satisfied, the valve body 62 is held in the valve closing position. On the other hand, when the fuel pressure in the low pressure passage 52 decreases due to fuel injection or the like of the first injection valve 21 and becomes “force in the valve closing direction <force in the valve opening direction”, the valve element 62 opens with the displacement of the diaphragm 68. To be spoken. At this time, the opening position (valve lift amount) of the valve body 62 is determined according to the difference between the force in the valve closing direction and the force in the valve opening direction, and the opening area of the valve seat 63 is changed according to the opening position. Is done. Further, the amount of fuel flowing from the high pressure passage 51 into the low pressure passage 52 is adjusted by changing the opening area.
　低圧通路５２から分岐した分岐部５２ａには、低圧通路５２内の燃料圧力が異常高圧になった場合にガス抜きをするリリーフ弁６９が設けられている。リリーフ弁６９は機械駆動式であり、低圧通路５２の燃料圧力が所定のリリーフ圧Ｐｒｅｆよりも高くなった場合に開弁する。 A relief valve 69 that vents gas when the fuel pressure in the low pressure passage 52 becomes abnormally high is provided in the branch portion 52a branched from the low pressure passage 52. The relief valve 69 is mechanically driven, and opens when the fuel pressure in the low pressure passage 52 becomes higher than a predetermined relief pressure Pref.
　本実施形態では、レギュレータ４３において、弁体６２や弁体作動部６５といった構成部品からなる圧力調整弁６０により圧力調整手段が構成されている。なお、図３の構成では、遮断弁４５と圧力センサ４６と圧力調整弁６０とを一体に設けたが、例えば遮断弁４５と圧力センサ４６とをレギュレータ４３とは別体として高圧配管部４１ａに設けることも可能である。 In the present embodiment, in the regulator 43, the pressure adjusting means is constituted by the pressure adjusting valve 60 made up of components such as the valve body 62 and the valve body operating portion 65. In the configuration of FIG. 3, the shut-off valve 45, the pressure sensor 46, and the pressure adjustment valve 60 are integrally provided. However, for example, the shut-off valve 45 and the pressure sensor 46 are separated from the regulator 43 in the high-pressure piping portion 41 a. It is also possible to provide it.
　図１の説明に戻り、液体燃料供給部７０において、第２噴射弁２２には、燃料配管７１を介して燃料タンク７２が接続されている。また、燃料配管７１には、燃料タンク７２内の液体燃料を第２噴射弁２２に給送する燃料ポンプ７３が設けられている。 1, in the liquid fuel supply unit 70, a fuel tank 72 is connected to the second injection valve 22 via a fuel pipe 71. The fuel pipe 71 is provided with a fuel pump 73 that feeds the liquid fuel in the fuel tank 72 to the second injection valve 22.
　制御部８０は、ＣＰＵ８１と、ＲＯＭ８２と、ＲＡＭ８３と、バックアップＲＡＭ８４と、インターフェース８５と、双方向バス８６とを備えている。ＣＰＵ８１、ＲＯＭ８２、ＲＡＭ８３、バックアップＲＡＭ８４、及びインターフェース８５は、双方向バス８６によって互いに接続されている。 The control unit 80 includes a CPU 81, a ROM 82, a RAM 83, a backup RAM 84, an interface 85, and a bidirectional bus 86. The CPU 81, ROM 82, RAM 83, backup RAM 84, and interface 85 are connected to each other by a bidirectional bus 86.
　ＣＰＵ８１は、本システムにおける各部の動作を制御するためのルーチン（プログラム）を実行する。ＲＯＭ８２には、ＣＰＵ８１が実行するルーチン、及びこのルーチン実行の際に参照されるマップ類（マップの他、テーブルや関係式等を含む）、パラメータ等の各種データが予め格納されている。ＲＡＭ８３は、ＣＰＵ８１がルーチンを実行する際に、必要に応じてデータを一時的に格納する。バックアップＲＡＭ８４は、電源が投入された状態でＣＰＵ８１の制御下でデータを適宜格納するとともに、この格納されたデータを電源遮断後も保持する。 The CPU 81 executes a routine (program) for controlling the operation of each unit in the system. The ROM 82 stores in advance various data such as a routine executed by the CPU 81, maps (including tables, relational expressions, etc. in addition to maps) and parameters referred to when the routine is executed. The RAM 83 temporarily stores data as necessary when the CPU 81 executes a routine. The backup RAM 84 appropriately stores data under the control of the CPU 81 in a state where the power is turned on, and retains the stored data even after the power is shut off.
　インターフェース８５は、上述したスロットル開度センサ１５ｂ、排気センサ１８、圧力センサ４６，４８、温度センサ４７，４９を含む、本システムに設けられたセンサ類（クランク角センサ、エアフロメータ、冷却水温センサ、車速センサ、アクセルセンサ等）と電気的に接続されており、これらのセンサからの出力（検出信号）をＣＰＵ８１に伝達する。また、インターフェース８５は、スロットルアクチュエータ１５ａ、点火装置２０ａ、各噴射弁２１，２２、タンク主止弁４４、遮断弁４５等の駆動部と電気的に接続されていて、これらの駆動部を駆動させるためにＣＰＵ８１から送出された駆動信号を当該駆動部に向けて出力する。すなわち、制御部８０は、上述のセンサ類の出力信号等に基づいてエンジン１０の運転状態を取得し、この運転状態に基づいて上述の駆動部の制御を実施する。 The interface 85 includes sensors (crank angle sensor, air flow meter, cooling water temperature sensor, etc.) provided in the present system, including the throttle opening sensor 15b, the exhaust sensor 18, the pressure sensors 46, 48, and the temperature sensors 47, 49 described above. Vehicle speed sensors, accelerator sensors, etc.) are electrically connected, and outputs (detection signals) from these sensors are transmitted to the CPU 81. The interface 85 is electrically connected to driving units such as the throttle actuator 15a, the ignition device 20a, the injection valves 21 and 22, the tank main stop valve 44, the shutoff valve 45, and the like, and drives these driving units. Therefore, the drive signal sent from the CPU 81 is output toward the drive unit. That is, the control unit 80 acquires the operating state of the engine 10 based on the output signals of the above-described sensors, and performs the above-described driving unit control based on this operating state.
　具体的には、例えばアクセルセンサにより検出されるアクセル操作量及びクランク角センサにより検出されるエンジン回転速度等に基づいて、エンジン１０の吸入空気量を算出し、その算出値に基づいてスロットルアクチュエータ１５ａの駆動を制御する。また、上記エンジン回転速度及びエアフロメータにより検出される吸入空気量等に基づいて燃料噴射量（燃料噴射時間）を算出し、その算出値に基づいて各噴射弁２１、２２の駆動を制御する。また、エンジン回転速度及び吸入空気量等に基づいて最適点火時期を算出し、その最適点火時期で点火が行われるように点火装置２０ａの駆動を制御する。 Specifically, for example, the intake air amount of the engine 10 is calculated based on the accelerator operation amount detected by the accelerator sensor, the engine rotational speed detected by the crank angle sensor, and the like, and the throttle actuator 15a is calculated based on the calculated value. Control the drive. Further, the fuel injection amount (fuel injection time) is calculated based on the engine speed and the intake air amount detected by the air flow meter, and the driving of the injection valves 21 and 22 is controlled based on the calculated value. Further, the optimal ignition timing is calculated based on the engine rotation speed, the intake air amount, and the like, and the drive of the ignition device 20a is controlled so that ignition is performed at the optimal ignition timing.
　点火装置２０ａやタンク主止弁４４、遮断弁４５には、制御部８０から制御信号が入力されるようになっている。具体的には、点火装置２０ａは、制御部８０からの制御信号に応じて高電圧を出力し点火プラグに点火火花を生じさせる。タンク主止弁４４及び遮断弁４５は、それぞれ独立に、制御部８０からの制御信号に応じて閉弁状態から開弁状態に切り替えられる。 A control signal is input from the control unit 80 to the ignition device 20a, the tank main stop valve 44, and the shutoff valve 45. Specifically, the ignition device 20a outputs a high voltage in response to a control signal from the control unit 80, and generates an ignition spark in the ignition plug. The tank main stop valve 44 and the shutoff valve 45 are independently switched from the closed state to the open state in accordance with a control signal from the control unit 80.
　制御部８０は、エンジン運転状態やタンク内の燃料残量、図示しない燃料選択スイッチからの入力信号等に応じて使用燃料を選択的に切り替えている。具体的には、ガスタンク４２内のガス燃料の残存量が所定値を下回った場合又は燃料選択スイッチにより液体燃料の使用が選択されている場合には、液体燃料を優先的に使用する。燃料タンク７２内の液体燃料の残存量が所定値を下回った場合又は燃料選択スイッチによりガス燃料の使用が選択されている場合には、ガス燃料を優先的に使用する。 The control unit 80 selectively switches the fuel to be used according to the engine operating state, the fuel remaining amount in the tank, an input signal from a fuel selection switch (not shown), and the like. Specifically, when the remaining amount of the gas fuel in the gas tank 42 falls below a predetermined value or when the use of the liquid fuel is selected by the fuel selection switch, the liquid fuel is preferentially used. When the remaining amount of liquid fuel in the fuel tank 72 falls below a predetermined value or when the use of gas fuel is selected by the fuel selection switch, the gas fuel is preferentially used.
　レギュレータ４３の圧力調整弁６０において、弁座部６３に異物が噛み込むと、その異物の大きさに応じた開度だけ圧力調整弁６０が常に開弁した状態で保持される。つまり、圧力調整弁６０が完全に閉じ切れず、燃料通路の高圧側と低圧側とが連通した状態になる。この場合、例えばアイドル運転時などの低負荷運転状態において、第１噴射弁２１から噴射される燃料量よりも、高圧側から低圧側に漏れ出る燃料量の方が多くなり、これにより、第１噴射弁２１への供給ガス圧（噴射圧）が意図せずに上昇するおそれがある。かかる場合、第１噴射弁２１により噴射可能な最小のガス燃料量が大きくなってしまい、その結果、低負荷運転状態において燃料噴射量が過多になることが懸念される。つまり、ガス燃料の圧力とガス密度とは比例関係にあるため、第１噴射弁２１への供給ガス圧が高いほど、同じ噴射時間（噴射弁通電時間）であっても実際の燃料噴射量が増え、第１噴射弁２１から噴射可能な最小燃料量が増えてしまう。 In the pressure adjusting valve 60 of the regulator 43, when a foreign object is caught in the valve seat 63, the pressure adjusting valve 60 is always kept open by an opening degree corresponding to the size of the foreign object. That is, the pressure regulating valve 60 is not completely closed, and the high pressure side and the low pressure side of the fuel passage are in communication with each other. In this case, for example, in a low load operation state such as during idle operation, the amount of fuel leaking from the high pressure side to the low pressure side is greater than the amount of fuel injected from the first injection valve 21, thereby There is a possibility that the supply gas pressure (injection pressure) to the injection valve 21 may increase unintentionally. In such a case, there is a concern that the minimum amount of gas fuel that can be injected by the first injection valve 21 increases, and as a result, the fuel injection amount becomes excessive in a low-load operation state. That is, since the pressure of the gas fuel and the gas density are in a proportional relationship, the higher the supply gas pressure to the first injection valve 21, the more the actual fuel injection amount even at the same injection time (injection valve energization time). As a result, the minimum amount of fuel that can be injected from the first injection valve 21 increases.
　なお、弁座部６３に噛み込む（付着する）異物としては、例えば圧力調整弁６０において、ガス燃料が弁座部６３を通過する際に、減圧作用による液化によって生じる液化物質が挙げられる。ガス燃料にはオイル成分が含まれるため、この液化物質はオイル成分を含む粘性の高い物質となる。圧力調整弁６０では、このような粘性の高い物質が弁座部６３に付着することによって所定開度だけ開いた状態となり、高圧側から低圧側への燃料リークが生じる。こうした不都合は、圧力調整弁６０の上流側にフィルタを設けた場合にも生じることは十分に考えられる。 In addition, examples of the foreign matter that bites into (adheres to) the valve seat portion 63 include a liquefied substance that is generated by liquefaction due to a depressurization action when gas fuel passes through the valve seat portion 63 in the pressure regulating valve 60. Since the gas fuel contains an oil component, the liquefied substance becomes a highly viscous substance containing the oil component. In the pressure regulating valve 60, such a highly viscous substance adheres to the valve seat portion 63 to be opened by a predetermined opening, and fuel leakage from the high pressure side to the low pressure side occurs. Such inconvenience can be considered to occur even when a filter is provided on the upstream side of the pressure regulating valve 60.
　そこで本実施形態では、第１噴射弁２１への供給ガス圧が所定値（判定値Ｋ１）を超える高圧状態となった場合に、遮断制御弁（タンク主止弁４４及び遮断弁４５のうち少なくともいずれか）を閉弁状態にするとともに、エンジン負荷に応じてガス燃料の使用を制限する、具体的には、エンジン負荷に応じて、第１噴射弁２１による燃料噴射から第２噴射弁２２による燃料噴射への切り替えを実施するか実施しないかを選択する。また、ガス燃料の使用から液体燃料の使用への切り替え後において、その時の第１噴射弁２１への供給ガス圧でも適正な燃料噴射が可能となった時点で、第１噴射弁２１による燃料噴射、すなわちガス燃料の使用を再開させるようにしている。 Therefore, in the present embodiment, when the supply gas pressure to the first injection valve 21 becomes a high pressure state exceeding a predetermined value (determination value K1), at least one of the cutoff control valve (the tank main stop valve 44 and the cutoff valve 45). 1) is closed, and the use of gas fuel is restricted according to the engine load. Specifically, depending on the engine load, the fuel injection from the first injection valve 21 to the second injection valve 22 Select whether or not to switch to fuel injection. In addition, after switching from the use of gas fuel to the use of liquid fuel, fuel injection by the first injection valve 21 becomes possible when proper fuel injection is possible even with the supply gas pressure to the first injection valve 21 at that time. That is, the use of gas fuel is resumed.
　図４は、第１噴射弁２１への供給ガス圧と燃料の使用領域との関係を示す概略図である。図４の横軸は第１噴射弁２１への供給ガス圧を示し、縦軸はエンジン負荷の大きさを示している。なお、エンジン負荷が大きいことは１燃焼当たりの要求燃料量が大きくなることに相当する。 FIG. 4 is a schematic diagram showing the relationship between the gas pressure supplied to the first injection valve 21 and the fuel use area. The horizontal axis of FIG. 4 shows the supply gas pressure to the first injection valve 21, and the vertical axis shows the magnitude of the engine load. A large engine load corresponds to an increase in the required fuel amount per combustion.
　図４において、破線Ｌ１で示す設定圧Ｐｒｅｇは、圧力調整弁６０により減圧調整される圧力値である。本実施形態では、この設定圧Ｐｒｅｇよりも高圧側に判定値Ｋ１が定められている。判定値Ｋ１は、アイドル運転時において第１噴射弁２１から噴射可能な最小燃料量Ｑｍｉｎを考慮して定められている。具体的には、第１噴射弁２１への供給ガス圧が判定値Ｋ１以上となる領域では、ガス密度の上昇に起因して最小燃料量Ｑｍｉｎが増大し、第１噴射弁２１によるガス燃料の噴射を実施した場合に、実際の燃料噴射量が、エンジン負荷に応じて定められる要求燃料量Ｑａよりも過多になる、つまり「最小燃料量Ｑｍｉｎ＞要求燃料量Ｑａ」となってしまうことを意味する。 In FIG. 4, the set pressure Preg indicated by the broken line L1 is a pressure value adjusted by the pressure adjusting valve 60 to reduce the pressure. In the present embodiment, the determination value K1 is determined on the higher pressure side than the set pressure Preg. The determination value K1 is determined in consideration of the minimum fuel amount Qmin that can be injected from the first injection valve 21 during idle operation. Specifically, in the region where the supply gas pressure to the first injection valve 21 is equal to or higher than the determination value K1, the minimum fuel amount Qmin increases due to the increase in gas density, and the gas fuel by the first injection valve 21 increases. It means that when the injection is performed, the actual fuel injection amount becomes excessive than the required fuel amount Qa determined according to the engine load, that is, “minimum fuel amount Qmin> required fuel amount Qa”. To do.
　また、要求燃料量Ｑａはエンジン負荷に応じて相違し、高負荷側ほど要求燃料量Ｑａが多くなる。これを考慮し、本実施形態ではガス燃料の使用領域と液体燃料の使用領域とを定めている。具体的には、図４に実線Ｌ２で示すように、第１噴射弁２１の作動が許容される供給ガス圧の範囲内において（作動限界圧Ｐｌｉｍよりも低圧側の領域において）、高負荷側ほどガス燃料の使用を許容する、換言すれば、低負荷側ほどガス燃料の使用を制限するようにしている。図４では、噴射圧が判定値Ｋ１を超える領域においてガス燃料の使用が制限される領域を斜線で示している。なお、作動限界圧Ｐｌｉｍは、リリーフ圧よりも高圧側に設定されている。 Also, the required fuel amount Qa differs depending on the engine load, and the required fuel amount Qa increases as the load becomes higher. In consideration of this, in this embodiment, the use area of the gas fuel and the use area of the liquid fuel are determined. Specifically, as indicated by a solid line L2 in FIG. 4, within the range of the supply gas pressure in which the operation of the first injection valve 21 is allowed (in the region on the low pressure side than the operating limit pressure Plim), the high load side The use of gas fuel is allowed, in other words, the use of gas fuel is restricted on the lower load side. In FIG. 4, a region where the use of gas fuel is restricted in a region where the injection pressure exceeds the determination value K <b> 1 is indicated by hatching. Note that the operating limit pressure Plim is set higher than the relief pressure.
　本実施形態では、設定圧Ｐｒｅｇより低圧側においてガス燃料の使用領域と液体燃料の使用領域とが設定されている。図４では使用領域の境界線を実線Ｌ３で示しており、実線Ｌ３で仕切られた領域のうち供給ガス圧が高圧側の領域をガス燃料の使用領域とし、低圧側の領域を液体燃料の使用領域としている。 In this embodiment, the use area of the gas fuel and the use area of the liquid fuel are set on the lower pressure side than the set pressure Preg. In FIG. 4, the boundary line of the use region is indicated by a solid line L3. Among the regions partitioned by the solid line L3, the region where the supply gas pressure is high is the gas fuel use region, and the low pressure side is the liquid fuel use region. As an area.
　次に、本実施形態の燃料噴射制御の処理手順を図５のフローチャートを用いて説明する。本処理は、エンジン１０の運転が実施されている場合に制御部８０のＣＰＵ８１により所定周期で繰り返し実行される。 Next, the processing procedure of the fuel injection control of this embodiment will be described using the flowchart of FIG. This process is repeatedly executed at a predetermined cycle by the CPU 81 of the control unit 80 when the engine 10 is being operated.
　図５において、ステップＳ１００では、圧力センサ４８により検出される噴射圧が判定値Ｋ１以上であるか否かを判定する（第１判定手段）。「噴射圧≧判定値Ｋ１」である場合、ステップＳ１０１へ進み、遮断弁４５を開弁させる開指令を出力中か否かを判定する。開指令の出力中の場合、ステップＳ１０２へ進み、タンク主止弁４４を閉弁させる閉指令を出力し、ステップＳ１０３で、遮断弁４５を閉弁させる閉指令を出力する。 In FIG. 5, in step S100, it is determined whether or not the injection pressure detected by the pressure sensor 48 is greater than or equal to a determination value K1 (first determination means). If “injection pressure ≧ determination value K1”, the process proceeds to step S101, and it is determined whether or not an opening command for opening the shutoff valve 45 is being output. When the open command is being output, the process proceeds to step S102, where a close command for closing the tank main stop valve 44 is output, and in step S103, a close command for closing the shutoff valve 45 is output.
　続くステップＳ１０４では、エンジン運転状態（ここではエンジン負荷及びエンジン回転速度）に基づいて１燃焼当たりの要求燃料量Ｑａを算出する。また、圧力センサ４８により検出される噴射圧（第１噴射弁２１への供給ガス圧）に基づいて、第１噴射弁２１から噴射可能な最小の噴射量である最小燃料量Ｑｍｉｎを算出する。本実施形態では、噴射圧と最小燃料量Ｑｍｉｎとの関係が算出用マップとして予め記憶してあり、その算出用マップを用いて最小燃料量Ｑｍｉｎを算出する。図６にその算出用マップの一例を示す。図６では、噴射圧が高いほど最小燃料量Ｑｍｉｎが大きくなっている。 In the subsequent step S104, the required fuel amount Qa per combustion is calculated based on the engine operating state (here, engine load and engine speed). Further, based on the injection pressure detected by the pressure sensor 48 (supply gas pressure to the first injection valve 21), a minimum fuel amount Qmin, which is the minimum injection amount that can be injected from the first injection valve 21, is calculated. In the present embodiment, the relationship between the injection pressure and the minimum fuel amount Qmin is stored in advance as a calculation map, and the minimum fuel amount Qmin is calculated using the calculation map. FIG. 6 shows an example of the calculation map. In FIG. 6, the minimum fuel amount Qmin increases as the injection pressure increases.
　図５の説明に戻り、ステップＳ１０５では、要求燃料量Ｑａと最小燃料量Ｑｍｉｎとを比較する。要求燃料量Ｑａが最小燃料量Ｑｍｉｎよりも大きい場合には、ステップＳ１０６へ進み、第１噴射弁２１による燃料噴射、すなわちガス燃料の使用を選択する。一方、要求燃料量Ｑａが最小燃料量Ｑｍｉｎ以下である場合には、ステップＳ１０７へ進み、第２噴射弁２２による燃料噴射、すなわち液体燃料の使用を選択する（燃料切替手段）。そして本処理を終了する。 Referring back to FIG. 5, in step S105, the required fuel amount Qa is compared with the minimum fuel amount Qmin. When the required fuel amount Qa is larger than the minimum fuel amount Qmin, the process proceeds to step S106, and fuel injection by the first injection valve 21, that is, use of gas fuel is selected. On the other hand, when the required fuel amount Qa is equal to or less than the minimum fuel amount Qmin, the process proceeds to step S107, and fuel injection by the second injection valve 22, that is, use of liquid fuel is selected (fuel switching means). Then, this process ends.
　一方、ステップＳ１００で「噴射圧≧判定値Ｋ１」であると判定され、かつステップＳ１０１で遮断弁４５の開指令の出力中ではない、すなわち遮断弁４５を閉弁させる閉指令を出力中であると判定された場合、ステップＳ１０８へ進む。ステップＳ１０８では、噴射圧が判定値Ｋ２を超えているか否かを判定する（第２判定手段）。ここで、判定値Ｋ２は、設定圧Ｐｒｅｇ及び判定値Ｋ１よりも高圧側に定められており、本実施形態では、リリーフ圧Ｐｒｅｆ及び作動限界圧Ｐｌｉｍよりも低圧側に定められている（図４参照）。「噴射圧≦判定値Ｋ２」である場合、ステップＳ１０４～Ｓ１０７の処理を実行する。一方、「噴射圧＞判定値Ｋ２」である場合にはステップＳ１０９へ進み、エンジン１０の吸入空気量を増量補正し、ステップＳ１１０で点火時期を最適点火時期に対して遅角側に補正する（運転変更手段）。その後、ステップＳ１０４～Ｓ１０７の処理を実行し、本処理を終了する。なお、ここでのステップＳ１０６が「ガス切替手段」に相当する。 On the other hand, it is determined in step S100 that “injection pressure ≧ determination value K1”, and in step S101, the opening command for the shutoff valve 45 is not being output, that is, the closing command for closing the shutoff valve 45 is being output. If it is determined, the process proceeds to step S108. In step S108, it is determined whether or not the injection pressure exceeds a determination value K2 (second determination means). Here, the determination value K2 is determined on the higher pressure side than the set pressure Preg and the determination value K1, and in this embodiment, is determined on the lower pressure side than the relief pressure Pref and the operation limit pressure Plim (FIG. 4). reference). If “injection pressure ≦ determination value K2”, the processing of steps S104 to S107 is executed. On the other hand, if “injection pressure> determination value K2”, the routine proceeds to step S109, where the intake air amount of the engine 10 is increased and corrected, and in step S110, the ignition timing is corrected to the retard side with respect to the optimal ignition timing ( Operation change means). Thereafter, the processing of steps S104 to S107 is executed, and this processing is terminated. Here, step S106 corresponds to “gas switching means”.
　さて、噴射圧が判定値Ｋ１よりも低いとステップＳ１１１へ進み、遮断弁４５を閉弁させる閉指令を出力中であるか否かを判定する。閉指令の出力中である場合、ステップＳ１１２へ進み、噴射圧が判定値Ｋ３よりも低いか否かを判定する（第３判定手段）。ここで判定値Ｋ３は、判定値Ｋ１よりも低圧側に定められており、具体的には、エンジン１０を運転状態にしておくのに必要な噴射量を確保可能な噴射圧の最小値に定められている。「噴射圧≧判定値Ｋ３」であれば、一旦そのまま本処理を終了する。一方、「噴射圧＜判定値Ｋ３」であればステップＳ１１３へ進み、遮断弁４５を開弁させる開指令を出力し、続くステップＳ１１４では、タンク主止弁４４を開弁させる開指令を出力する。そして本処理を終了する。 If the injection pressure is lower than the determination value K1, the process proceeds to step S111, and it is determined whether or not a closing command for closing the shutoff valve 45 is being output. When the closing command is being output, the process proceeds to step S112, and it is determined whether or not the injection pressure is lower than the determination value K3 (third determination means). Here, the determination value K3 is determined to be lower than the determination value K1. Specifically, the determination value K3 is determined to be the minimum value of the injection pressure that can secure the injection amount necessary to keep the engine 10 in the operating state. It has been. If “injection pressure ≧ determination value K3”, the process is temporarily terminated. On the other hand, if “injection pressure <determination value K3”, the process proceeds to step S113 to output an opening command for opening the shut-off valve 45, and in subsequent step S114, an opening command for opening the tank main stop valve 44 is output. . Then, this process ends.
　次に、噴射圧が高圧状態になった場合の燃料噴射制御の具体的態様について、図７及び図８のタイムチャートを用いて説明する。 Next, a specific mode of fuel injection control when the injection pressure becomes a high pressure state will be described with reference to time charts of FIGS.
　図７は、ガス燃料の使用による低負荷運転時（例えばアイドル運転時など）において、例えば圧力調整弁６０の弁座部６３に異物が噛み込み、噴射圧が判定値Ｋ１を超えた場合を想定している。なお、エンジン運転中であることから、噴射圧が判定値Ｋ１を超える前ではタンク主止弁４４及び遮断弁４５は開弁状態となっている。 FIG. 7 assumes a case in which foreign matter is caught in the valve seat portion 63 of the pressure regulating valve 60 and the injection pressure exceeds the determination value K1 during low load operation (for example, during idle operation) using gas fuel. is doing. Since the engine is in operation, the tank main stop valve 44 and the shutoff valve 45 are open before the injection pressure exceeds the determination value K1.
　図７において、噴射圧が判定値Ｋ１を超えると、そのタイミングｔ１１でタンク主止弁４４を閉弁し、続いて遮断弁４５を閉弁する。互いの閉弁タイミングをずらすのは、タンク主止弁４４及び遮断弁４５の駆動時期が重複することによるバッテリ電圧の低下に起因して、各弁が開弁しにくくなることを回避するためである。また、タンク主止弁４４を先に閉弁する、つまりガス配管４１において上流側から先に閉弁するのは、各弁４４、４５の閉弁に伴う噴射圧の変動を抑制するためである。このとき、第１噴射弁２１について、要求燃料量Ｑａよりも最小燃料量Ｑｍｉｎの方が大きくなった時点で、第１噴射弁２１によるガス燃料の噴射から、第２噴射弁２２による液体燃料の噴射に切り替える。 7, when the injection pressure exceeds the determination value K1, the tank main stop valve 44 is closed at the timing t11, and then the shutoff valve 45 is closed. The reason for shifting the valve closing timing of each other is to prevent the valves from becoming difficult to open due to a decrease in battery voltage due to overlapping driving timings of the tank main stop valve 44 and the shutoff valve 45. is there. The tank main stop valve 44 is closed first, that is, the gas pipe 41 is closed first from the upstream side in order to suppress fluctuations in the injection pressure accompanying the closing of the valves 44 and 45. . At this time, when the minimum fuel amount Qmin is larger than the required fuel amount Qa for the first injection valve 21, the liquid fuel by the second injection valve 22 is injected from the gas fuel injection by the first injection valve 21. Switch to injection.
　「要求燃料量Ｑａ＜最小燃料量Ｑｍｉｎ」の期間（ｔ１１～ｔ１３）では、第１噴射弁２１によるガス燃料の噴射を実施すると燃料過多になってしまう。したがって、同期間ではガス燃料の使用を制限または禁止し、液体燃料に切り替えて現在のエンジン運転状態を維持する。また、タイミングｔ１２で、運転者によるアクセル操作に伴いエンジン１０の吸入空気量が増大すると、要求燃料量Ｑａが大きくなる。そして、「要求燃料量Ｑａ＞最小燃料量Ｑｍｉｎ」になると、そのタイミングｔ１３で、第２噴射弁２２による液体燃料の噴射から、第１噴射弁２１によるガス燃料の噴射に切り替える。このとき、タンク主止弁４４及び遮断弁４５については閉弁した状態のままにしておく。これにより、ガスタンク４２からの燃料供給が遮断された状態で第１噴射弁２１によるガス燃料の噴射が行われ、噴射圧が低下する（期間ｔ１３～ｔ１４）。 In the period of “required fuel amount Qa <minimum fuel amount Qmin” (t11 to t13), if the first fuel injection by the first injection valve 21 is performed, the fuel becomes excessive. Therefore, the use of gas fuel is restricted or prohibited during the same period, and the current engine operating state is maintained by switching to liquid fuel. Further, when the intake air amount of the engine 10 increases with the accelerator operation by the driver at the timing t12, the required fuel amount Qa increases. Then, when “required fuel amount Qa> minimum fuel amount Qmin” is reached, the liquid fuel injection by the second injection valve 22 is switched to the gas fuel injection by the first injection valve 21 at the timing t13. At this time, the tank main stop valve 44 and the shutoff valve 45 are kept closed. Accordingly, the gas fuel is injected by the first injection valve 21 in a state where the fuel supply from the gas tank 42 is shut off, and the injection pressure is reduced (periods t13 to t14).
　そして、噴射圧が判定値Ｋ３を下回ると、そのタイミングｔ１４で遮断弁４５を開弁し、続いてタンク主止弁４４を開弁する。これにより、第１噴射弁２１へのガス燃料の供給が許容され、噴射圧が上昇する。ここで、判定値Ｋ３は、ガス燃料の使用領域内に設定されており（図４参照）、これにより供給ガス圧が過度に低下することを回避するようにしている。また、本実施形態では、判定値Ｋ３を設定圧Ｐｒｅｇよりも低圧側に定めている。こうすることにより、遮断弁４５の開弁状態への切り替え時において圧力調整弁６０の開度を大きくしてガス流量を大きくすることにより、弁座部６３に付着した異物を取り除くようにしている。 When the injection pressure falls below the determination value K3, the shutoff valve 45 is opened at the timing t14, and then the tank main stop valve 44 is opened. Thereby, supply of the gas fuel to the 1st injection valve 21 is permitted, and an injection pressure rises. Here, the determination value K3 is set within the use region of the gas fuel (see FIG. 4), and thereby, the supply gas pressure is prevented from excessively decreasing. In the present embodiment, the determination value K3 is set to a lower pressure side than the set pressure Preg. By doing so, the foreign matter adhering to the valve seat 63 is removed by increasing the opening of the pressure regulating valve 60 and increasing the gas flow rate when the shut-off valve 45 is switched to the open state. .
　次に、ガス燃料の使用による低負荷運転時において、噴射圧が判定値Ｋ１を超えた後、更に判定値Ｋ２を超えた場合の燃料噴射制御について、図８のタイムチャートを用いて説明する。なお、エンジン運転中であることから、噴射圧が判定値Ｋ１を超える前ではタンク主止弁４４及び遮断弁４５は開弁状態となっている。 Next, fuel injection control when the injection pressure exceeds the determination value K1 and further exceeds the determination value K2 during low load operation using gas fuel will be described with reference to the time chart of FIG. Since the engine is in operation, the tank main stop valve 44 and the shutoff valve 45 are open before the injection pressure exceeds the determination value K1.
　図８において、噴射圧が判定値Ｋ１を超えると、そのタイミングｔ２１でタンク主止弁４４を閉弁し、続いて遮断弁４５を閉弁する。また、第１噴射弁２１において要求燃料量Ｑａよりも最小燃料量Ｑｍｉｎの方が大きくなった時点で、第１噴射弁２１によるガス燃料の噴射から、第２噴射弁２２による液体燃料の噴射に切り替える。 In FIG. 8, when the injection pressure exceeds the determination value K1, the tank main stop valve 44 is closed at the timing t21, and then the shutoff valve 45 is closed. In addition, when the minimum fuel amount Qmin is larger than the required fuel amount Qa in the first injection valve 21, the gas fuel injection from the first injection valve 21 is changed to the liquid fuel injection by the second injection valve 22. Switch.
　ここで、遮断弁４５の閉弁後において低負荷走行が継続され、ガス燃料の噴射機会が到来しない場合、すなわち「要求燃料量Ｑａ＜最小燃料量Ｑｍｉｎ」が継続した状態では、噴射圧が更に高圧化して判定値Ｋ２よりも高くなることがある。その一つの原因としては、例えば遮断弁４５から圧力調整弁６０までの燃料配管内の高圧のガス燃料が、圧力調整弁６０の弁座部６３を通って低圧側に流入するなどの理由が挙げられる。かかる場合、圧力調整弁６０と第１噴射弁２１との間の低圧通路部（低圧配管部４１ｂ、低圧通路５２）の高圧化に起因して第１噴射弁２１が開弁しにくくなることがある。 Here, when the low-load running is continued after the shut-off valve 45 is closed and the gas fuel injection opportunity does not arrive, that is, when “required fuel amount Qa <minimum fuel amount Qmin” continues, the injection pressure further increases. There is a case where the pressure is increased and becomes higher than the determination value K2. One reason is that, for example, high-pressure gas fuel in the fuel pipe from the shutoff valve 45 to the pressure regulating valve 60 flows into the low pressure side through the valve seat 63 of the pressure regulating valve 60. It is done. In such a case, the first injection valve 21 may be difficult to open due to the high pressure of the low pressure passage portion (low pressure pipe portion 41b, low pressure passage 52) between the pressure regulating valve 60 and the first injection valve 21. is there.
　低圧通路部の高圧状態において第１噴射弁２１が開弁しにくくなる理由は以下の通りである。すなわち、第１噴射弁２１は、閉鎖状態下で低圧通路部からのガス燃料の圧力によって閉鎖方向の力が付与され、その閉鎖方向の力によってガス燃料の流通を遮断するものである。したがって、第１噴射弁２１の開弁時には、その燃料圧力に打ち勝つ駆動力を生じさせる必要がある。一方、低圧通路部のガス燃料の圧力が高圧状態であると、第１噴射弁２１において閉鎖方向の力が大きく作用することとなり、第１噴射弁２１に開弁駆動信号を出力しても第１噴射弁２１を開弁できないおそれがある。 The reason why the first injection valve 21 is difficult to open in the high pressure state of the low pressure passage portion is as follows. That is, the first injection valve 21 is provided with a force in the closing direction by the pressure of the gas fuel from the low pressure passage portion in the closed state, and blocks the flow of the gas fuel by the force in the closing direction. Therefore, when the first injection valve 21 is opened, it is necessary to generate a driving force that overcomes the fuel pressure. On the other hand, if the pressure of the gas fuel in the low pressure passage is in a high pressure state, a force in the closing direction acts greatly on the first injection valve 21, and even if a valve opening drive signal is output to the first injection valve 21, There is a possibility that the one injection valve 21 cannot be opened.
　そこで、本実施形態では、低圧通路部の高圧化に起因して第１噴射弁２１が開弁しにくくなることを回避するべく、「噴射圧＞判定値Ｋ２」となった場合には、第１噴射弁２１によるガス燃料の噴射の制限を解除する、すなわち第２噴射弁２２による液体燃料の噴射から、第１噴射弁２１によるガス燃料の噴射に切り替えることとしている。また、ガス燃料の噴射に切り替える場合には、第１噴射弁２１から噴射されるガス燃料の消費を促進させる運転状態に変更することとしている（運転変更手段）。 Therefore, in the present embodiment, in order to avoid that the first injection valve 21 is difficult to open due to the high pressure in the low-pressure passage portion, when “injection pressure> the determination value K2”, The restriction on the injection of the gas fuel by the first injection valve 21 is canceled, that is, the liquid fuel injection by the second injection valve 22 is switched to the injection of the gas fuel by the first injection valve 21. Moreover, when switching to the injection of gas fuel, it is supposed to change to the driving | running state which promotes consumption of the gas fuel injected from the 1st injection valve 21 (operation change means).
　具体的には、タイミングｔ２１で液体燃料の使用に切り替えた後、噴射圧が更に上昇して判定値Ｋ２を超えた場合、そのタイミングｔ２２で、スロットル開度を開弁側に駆動して、吸入空気量を増量補正するとともに、吸入空気量に増加によるトルク増大を抑えるべく、点火時期を遅角側に変更する。なお、吸入空気量の増量補正はエンジン負荷に応じて行い、「要求燃料量Ｑａ＞最小燃料量Ｑｍｉｎ」となるように、低負荷側ほど補正量を大きくする。この動作により要求燃料量Ｑａが増大し、「要求燃料量Ｑａ＞最小燃料量Ｑｍｉｎ」になった後のタイミングｔ２３で、第２噴射弁２２による液体燃料の使用から、第１噴射弁２１によるガス燃料の使用に切り替える。つまり、第１噴射弁２１からの燃料噴射によってガス燃料の消費を促進させる。このとき、タンク主止弁４４及び遮断弁４５は閉弁した状態のままであることから、第１噴射弁２１によるガス燃料の噴射によって噴射圧が低下する。 Specifically, after switching to the use of liquid fuel at the timing t21, when the injection pressure further increases and exceeds the determination value K2, the throttle opening is driven to the valve opening side at the timing t22, and the suction is performed. While increasing the air amount, the ignition timing is changed to the retarded side in order to suppress an increase in torque due to the increase in the intake air amount. The increase correction of the intake air amount is performed according to the engine load, and the correction amount is increased toward the lower load side so that “required fuel amount Qa> minimum fuel amount Qmin”. As a result of this operation, the required fuel amount Qa increases, and at timing t23 after “required fuel amount Qa> minimum fuel amount Qmin”, the liquid fuel used by the second injection valve 22 is changed to the gas generated by the first injection valve 21. Switch to using fuel. That is, consumption of gas fuel is promoted by fuel injection from the first injection valve 21. At this time, since the tank main stop valve 44 and the shut-off valve 45 remain closed, the injection pressure is reduced by the injection of gas fuel by the first injection valve 21.
　そして、噴射圧が判定値Ｋ３を下回ると、そのタイミングｔ２４で遮断弁４５を開弁し、続いてタンク主止弁４４を開弁する。また、各弁４４、４５の開弁に伴い噴射圧が設定圧Ｐｒｅｇに調整された後において、吸入空気量の増量補正を解除するとともに、点火遅角を解除する。 When the injection pressure falls below the determination value K3, the shutoff valve 45 is opened at the timing t24, and then the tank main stop valve 44 is opened. Further, after the injection pressure is adjusted to the set pressure Preg as the valves 44 and 45 are opened, the increase correction of the intake air amount is canceled and the ignition retard is also released.
　以上詳述した第１実施形態によれば、次の優れた効果が得られる。 According to the first embodiment described in detail above, the following excellent effects can be obtained.
　噴射圧が判定値Ｋ１よりも高圧状態となった場合に、遮断制御弁としてのタンク主止弁４４及び遮断弁４５を閉弁するとともに、エンジン負荷に応じてガス燃料の使用を制限して液体燃料の使用に切り替える構成とした。噴射圧が高いほどガス密度が高くなるため、噴射圧が高い場合にガス燃料を使用するとエンジン１０の低負荷状態において噴射燃料が過多になることが生じ得る。その点、上記構成によれば、噴射燃料が過多になることを回避することができる。したがって、噴射圧が設定圧力より高圧状態となった場合にも適切な燃料噴射制御を実施することができる。 When the injection pressure is higher than the judgment value K1, the tank main stop valve 44 and the shutoff valve 45 as shutoff control valves are closed, and the use of gas fuel is restricted according to the engine load. The configuration is switched to using fuel. Since the gas density increases as the injection pressure increases, the use of gas fuel when the injection pressure is high may result in an excess of injected fuel in a low load state of the engine 10. In that respect, according to the above configuration, it is possible to avoid an excessive amount of injected fuel. Therefore, appropriate fuel injection control can be performed even when the injection pressure is higher than the set pressure.
　具体的には、第１噴射弁２１において噴射可能な燃料量の最小値として、噴射圧に応じて定められる最小燃料量Ｑｍｉｎと、エンジン負荷に応じて定められる要求燃料量Ｑａとを比較し、その比較結果に基づいて、ガス燃料の使用から液体燃料の使用に切り替える構成とした。こうすることにより、「要求燃料量Ｑａ＞最小燃料量Ｑｍｉｎ」であり、第１噴射弁２１によるガス燃料の噴射を実施しても燃料過多が生じない状況下では、ガス燃料を優先して使用することができる。一方、「要求燃料量Ｑａ＜最小燃料量Ｑｍｉｎ」であり、第１噴射弁２１によるガス燃料の噴射を実施すると燃料過多が生じ得る状況下では、ガス燃料の使用を制限することによりエミッションの悪化を回避することができる。 Specifically, as a minimum value of the fuel amount that can be injected in the first injection valve 21, the minimum fuel amount Qmin determined according to the injection pressure is compared with the required fuel amount Qa determined according to the engine load, Based on the comparison result, the configuration is switched from the use of gas fuel to the use of liquid fuel. By doing so, in a situation where “required fuel amount Qa> minimum fuel amount Qmin” and there is no excess fuel even when the fuel injection by the first injection valve 21 is performed, the gas fuel is used preferentially. can do. On the other hand, in a situation where “required fuel amount Qa <minimum fuel amount Qmin” and excessive fuel may occur when the fuel injection by the first injection valve 21 is performed, the use of the gas fuel is limited to deteriorate the emission. Can be avoided.
　ガス燃料の噴射から液体燃料の噴射への切り替え後において、要求燃料量Ｑａが最小燃料量Ｑｍｉｎよりも大きくなった場合に（図７のタイミングｔ１３で）、遮断制御弁としてのタンク主止弁４４及び遮断弁４５を閉弁した状態のまま、液体燃料の噴射からガス燃料の噴射に切り替える構成とした。これにより、低圧通路部の燃料圧力を積極的に低下させることができ、高圧状態を解消することができる。 When the required fuel amount Qa becomes larger than the minimum fuel amount Qmin after switching from gas fuel injection to liquid fuel injection (at timing t13 in FIG. 7), the tank main stop valve 44 serving as a shutoff control valve. In addition, the liquid fuel injection is switched to the gas fuel injection while the shutoff valve 45 is closed. As a result, the fuel pressure in the low pressure passage portion can be actively reduced, and the high pressure state can be eliminated.
　ガス燃料の噴射から液体燃料の噴射への切り替え後において、第１噴射弁２１への供給ガス圧（噴射圧）が更に高圧化して判定値Ｋ２を超えた場合には、遮断制御弁を閉弁した状態のまま、液体燃料の噴射からガス燃料の噴射に切り替える構成とした。第１噴射弁２１への供給ガス圧が過度に高くなると、その高圧状態に起因して第１噴射弁２１を開弁できなくなるおそれがある。この点を考慮し、上記構成とすることにより、第１噴射弁２１を開弁できなくなるといった不都合が生じないようにすることができる。 After switching from gas fuel injection to liquid fuel injection, when the supply gas pressure (injection pressure) to the first injection valve 21 further increases and exceeds the determination value K2, the shutoff control valve is closed. In this state, the liquid fuel injection is switched to the gas fuel injection. If the supply gas pressure to the first injection valve 21 becomes excessively high, the first injection valve 21 may not be opened due to the high pressure state. Considering this point, by adopting the above-described configuration, it is possible to prevent the inconvenience that the first injection valve 21 cannot be opened.
　また特に、第１噴射弁２１への供給ガス圧が判定値Ｋ２を超えたことに伴い第１噴射弁２１によるガス燃料の噴射に切り替える場合、ガス燃料の消費を促進させる運転状態に変更する。具体的には、「要求燃料量Ｑａ＞最小燃料量Ｑｍｉｎ」となるようにエンジン負荷に応じてエンジン１０の吸入空気量を増量補正するとともに、点火時期を遅角側に補正する構成とした。この構成によれば、エンジン１０の燃焼によってガス燃料を消費させることにより、低圧通路部の高圧状態を解消することができる。また、点火時期の遅角補正を併せて行うことから、吸入空気量の増量補正を行った場合にもトルク増大が生じないようにすることができる。 In particular, when switching to gas fuel injection by the first injection valve 21 when the supply gas pressure to the first injection valve 21 exceeds the determination value K2, the operation state is changed to promote the consumption of gas fuel. Specifically, the intake air amount of the engine 10 is increased and corrected according to the engine load so that “required fuel amount Qa> minimum fuel amount Qmin”, and the ignition timing is corrected to the retard side. According to this configuration, the gas fuel is consumed by the combustion of the engine 10, whereby the high pressure state of the low pressure passage portion can be eliminated. Further, since the ignition timing retardation correction is also performed, it is possible to prevent an increase in torque even when the intake air amount increase correction is performed.
　第１噴射弁２１への供給ガス圧が判定値Ｋ２を超えたことに伴い第１噴射弁２１によるガス燃料の噴射に切り替えた後において、噴射圧が判定値Ｋ３を下回った場合にタンク主止弁４４及び遮断弁４５を開弁する構成とした。これにより、供給ガス圧が過度に低下することを回避することができる。また特に、判定値Ｋ３を設定圧Ｐｒｅｇよりも低圧側に定めたため、タンク主止弁４４及び遮断弁４５の開弁状態への切り替え時において弁座部６３を通過するガス流量を大きくでき、この流量大によって、弁座部６３に付着した異物を取り除きやすくすることができる。 After the supply gas pressure to the first injection valve 21 exceeds the determination value K2, the tank main stop is performed when the injection pressure falls below the determination value K3 after switching to the injection of gas fuel by the first injection valve 21. The valve 44 and the shutoff valve 45 are configured to open. Thereby, it can avoid that supply gas pressure falls too much. In particular, since the determination value K3 is determined to be lower than the set pressure Preg, the flow rate of the gas passing through the valve seat 63 can be increased when the tank main stop valve 44 and the shutoff valve 45 are switched to the open state. By the large flow rate, it is possible to easily remove foreign matters adhering to the valve seat portion 63.
　判定値Ｋ２を、リリーフ圧Ｐｒｅｆ及び作動限界圧Ｐｌｉｍよりも低圧側に定めたため、リリーフ弁６９が開弁する前（ガス燃料が大気中に放出される前）であって、かつ第１噴射弁２１が開弁できなくなる前に低圧通路部の高圧状態を緩和することができる。 Since the determination value K2 is set to be lower than the relief pressure Pref and the operation limit pressure Plim, the first injection valve is before the relief valve 69 is opened (before the gas fuel is released into the atmosphere). The high pressure state of the low pressure passage portion can be relaxed before the valve 21 cannot be opened.
　（第２実施形態）
　上記第１実施形態では、噴射圧が判定値Ｋ２を超えたことを条件に、第１噴射弁２１によるガス燃料の噴射に切り替えて噴射圧を低下させる構成とした。これに対し、本実施形態では、噴射圧が判定値Ｋ２を超えたこと、及び減速時の燃料カット要求が生じている期間であることを条件に、第１噴射弁２１によるガス燃料の噴射に切り替えて噴射圧を低下させる構成とする。減速時の燃料カット中に点火カット状態でガス燃料を噴射する構成とすることにより、ドライバビリティに及ぼす影響を極力少なくしつつ、噴射圧を低下させることができる。 (Second Embodiment)
In the said 1st Embodiment, it was set as the structure which switches to the injection of the gas fuel by the 1st injection valve 21, and reduces an injection pressure on condition that the injection pressure exceeded determination value K2. On the other hand, in the present embodiment, on the condition that the injection pressure exceeds the determination value K2 and the fuel cut request at the time of deceleration is occurring, the first fuel injection by the first injection valve 21 is performed. It is set as the structure which switches and reduces an injection pressure. By adopting a configuration in which gas fuel is injected in the ignition cut state during fuel cut during deceleration, the injection pressure can be reduced while minimizing the influence on drivability.
　噴射圧と最小燃料量Ｑｍｉｎとは比例関係にあり、噴射圧が高いほど、１回当たりに噴射可能な最小燃料量Ｑｍｉｎは多くなる。一方、減速時の燃料カット中では、触媒温度の低下を抑制する観点から、吸入空気量の増量補正に限界がある。したがって、噴射圧が判定値Ｋ２を超えた場合に第１噴射弁２１によるガス燃料の噴射を実施する際に、通常運転時と同じように各気筒で所定位相毎に（３気筒エンジンであれば２４０℃Ａの噴射周期で）燃料噴射を実施すると燃料過多になることが考えられる。かかる場合、エミッションの悪化を招いたり、触媒温度の過昇温を招いたりするおそれがある。本実施形態では、減速時の燃料カット期間中であることを条件に第１噴射弁２１によるガス燃料の噴射に切り替える場合には、噴射周期を各気筒の１燃焼サイクルよりも長くして第１噴射弁２１によるガス燃料の噴射を実施することとしている。 The injection pressure and the minimum fuel amount Qmin are in a proportional relationship, and the higher the injection pressure, the larger the minimum fuel amount Qmin that can be injected per time. On the other hand, during the fuel cut during deceleration, there is a limit to the increase correction of the intake air amount from the viewpoint of suppressing the decrease in the catalyst temperature. Therefore, when the injection of gas fuel by the first injection valve 21 is performed when the injection pressure exceeds the determination value K2, each cylinder has a predetermined phase (if it is a three-cylinder engine) as in normal operation. If fuel injection is performed (with an injection cycle of 240 ° C. A), it is conceivable that fuel will be excessive. In such a case, the emission may be deteriorated or the catalyst temperature may be excessively increased. In the present embodiment, when switching to gas fuel injection by the first injection valve 21 on the condition that the fuel cut period is during deceleration, the first injection cycle is made longer than one combustion cycle of each cylinder. The injection of gas fuel by the injection valve 21 is performed.
　図９は、本実施形態の燃料噴射制御の具体的態様を示すタイムチャートである。図９において、噴射圧が判定値Ｋ１を超えると、そのタイミングｔ３１でタンク主止弁４４を閉弁し、続いて遮断弁４５を閉弁する。また、第１噴射弁２１において要求燃料量Ｑａよりも最小燃料量Ｑｍｉｎの方が大きくなった時点で、第１噴射弁２１によるガス燃料の噴射から、第２噴射弁２２による液体燃料の噴射に切り替える。 FIG. 9 is a time chart showing a specific aspect of the fuel injection control of the present embodiment. In FIG. 9, when the injection pressure exceeds the determination value K1, the tank main stop valve 44 is closed at the timing t31, and then the shutoff valve 45 is closed. In addition, when the minimum fuel amount Qmin is larger than the required fuel amount Qa in the first injection valve 21, the gas fuel injection from the first injection valve 21 is changed to the liquid fuel injection by the second injection valve 22. Switch.
　その後、噴射圧が判定値Ｋ２を超えた場合（ｔ３２）、減速時の燃料カットが開始されたことを条件に、第１噴射弁２１によるガス燃料の噴射に切り替える。具体的には、「噴射圧＞判定値Ｋ２」となった後のタイミングｔ３３で減速時の燃料カット条件が成立すると、スロットル開度を開弁側に駆動して吸入空気量を増量補正する。また、タイミングｔ３４では、第２噴射弁２２による液体燃料の噴射から、第１噴射弁２１によるガス燃料の噴射に切り替える。ただし、第１噴射弁２１によるガス燃料の噴射は間欠的に実施する。具体的には、噴射周期を各気筒の１燃焼サイクルよりも長くして第１噴射弁２１によるガス燃料の噴射を実施する。例えば、３気筒エンジンであれば、３気筒のうち特定気筒でのみガス燃料の噴射を実施し、他の気筒についてはガス燃料の噴射を実施しないようにする。このガス燃料の噴射により噴射圧が低下し、「噴射圧＜判定値Ｋ３」となったタイミングｔ３５で吸入空気量の増量補正を解除する。 After that, when the injection pressure exceeds the determination value K2 (t32), switching to gas fuel injection by the first injection valve 21 is performed on the condition that the fuel cut at the time of deceleration is started. Specifically, when the fuel cut condition during deceleration is satisfied at timing t33 after “injection pressure> determination value K2”, the throttle opening is driven to the valve opening side to increase the intake air amount. In addition, at timing t <b> 34, the liquid fuel injection by the second injection valve 22 is switched to the gas fuel injection by the first injection valve 21. However, the injection of gas fuel by the first injection valve 21 is performed intermittently. Specifically, the injection cycle is made longer than one combustion cycle of each cylinder, and the gas fuel is injected by the first injection valve 21. For example, in the case of a three-cylinder engine, the gas fuel is injected only in a specific cylinder among the three cylinders, and the gas fuel is not injected in the other cylinders. The injection pressure is reduced by the injection of the gas fuel, and the increase correction of the intake air amount is canceled at timing t35 when “injection pressure <determination value K3”.
　次に、本実施形態の燃料噴射制御の処理手順を図１０のフローチャートを用いて説明する。本処理は、エンジン運転状態において制御部８０のＣＰＵ８１により所定周期で繰り返し実行される。なお、上記図５のフローチャートと同じ処理については、図５のステップ番号を付してその説明を省略する。 Next, the processing procedure of the fuel injection control of this embodiment will be described using the flowchart of FIG. This process is repeatedly executed at a predetermined cycle by the CPU 81 of the control unit 80 in the engine operating state. The same processes as those in the flowchart of FIG. 5 are denoted by step numbers in FIG. 5 and description thereof is omitted.
　図１０において、ステップＳ２００～Ｓ２０８は、上記図５のステップＳ１００～Ｓ１０８とそれぞれ同じ処理である。ステップＳ２０８で「噴射圧＞判定値Ｋ２」であると判定されると、ステップＳ２０９へ進み、減速時の燃料カット条件が成立しているか否かを判定する（条件判定手段）。減速時の燃料カット条件としては、運転者によるアクセル操作量がゼロであること、エンジン回転速度が所定値以上であること等を含む。減速時の燃料カット条件が成立している場合には、ステップＳ２１０へ進み、触媒温度が所定範囲内であるか否かを判定する。触媒温度が低すぎるとガス燃料が触媒１９で処理されず、高温すぎるとガス燃料が燃焼することによって触媒温度が過昇温するおそれがある。なお、触媒温度は、排気温度を検出する温度センサの検出値に基づいて推定してもよいし、触媒温度を検出するセンサが設けられている場合にはその検出値を用いてもよい。 In FIG. 10, steps S200 to S208 are the same as steps S100 to S108 in FIG. If it is determined in step S208 that “injection pressure> determination value K2”, the process proceeds to step S209, and it is determined whether or not a fuel cut condition during deceleration is satisfied (condition determination means). The fuel cut condition at the time of deceleration includes that the amount of accelerator operation by the driver is zero, the engine rotation speed is a predetermined value or more, and the like. When the fuel cut condition at the time of deceleration is satisfied, the process proceeds to step S210, and it is determined whether or not the catalyst temperature is within a predetermined range. If the catalyst temperature is too low, the gas fuel is not treated with the catalyst 19, and if it is too high, the gas fuel may burn and the catalyst temperature may be overheated. The catalyst temperature may be estimated based on a detection value of a temperature sensor that detects the exhaust gas temperature, or the detection value may be used when a sensor that detects the catalyst temperature is provided.
　触媒温度が所定範囲内になければ、ステップＳ２１１へ進み、燃料噴射及び点火を禁止する。一方、触媒温度が所定範囲内であれば、ステップＳ２１２へ進み、点火カットを実施するとともに、ステップＳ２１３で吸入空気量を増量補正する。また、ステップＳ２１４では、第１噴射弁２１によるガス燃料の間欠噴射を実施する。このガス燃料の間欠噴射によって噴射圧が低下する。ステップＳ２１５及びＳ２１６では、図５のステップＳ１１１及びＳ１１２の処理を実行し、ステップＳ２１７で減速時の燃料カット中か否かを判定する。減速時の燃料カット中でないことを条件にステップＳ２１８へ進み、図５のステップＳ１１３及びＳ１１４と同じ処理を実行し、本処理を終了する。 If the catalyst temperature is not within the predetermined range, the process proceeds to step S211, and fuel injection and ignition are prohibited. On the other hand, if the catalyst temperature is within the predetermined range, the process proceeds to step S212, the ignition cut is performed, and the intake air amount is increased and corrected in step S213. Further, in step S214, the gas fuel is intermittently injected by the first injection valve 21. The injection pressure is reduced by the intermittent injection of the gas fuel. In steps S215 and S216, the processing in steps S111 and S112 in FIG. 5 is executed, and it is determined in step S217 whether or not the fuel is being cut during deceleration. The process proceeds to step S218 on condition that the fuel cut at the time of deceleration is not being performed, the same processing as steps S113 and S114 in FIG. 5 is executed, and this processing is terminated.
　以上詳述した第２実施形態によれば次の効果が得られる。 According to the second embodiment described in detail above, the following effects can be obtained.
　噴射圧が判定値Ｋ２を超えた場合には、減速時の燃料カット期間中に第１噴射弁２１によるガス燃料の噴射に切り替えて噴射圧を低下させる構成とした。減速時の燃料カット中に点火カット状態でガス燃料を噴射することにより、ドライバビリティへの影響をできるだけ小さくしつつ、噴射圧を設定圧Ｐｒｅｇまで低下させることができる。 When the injection pressure exceeds the determination value K2, the injection pressure is reduced by switching to gas fuel injection by the first injection valve 21 during the fuel cut period during deceleration. By injecting gas fuel in the ignition cut state during fuel cut during deceleration, the injection pressure can be reduced to the set pressure Preg while minimizing the influence on drivability.
　「噴射圧＞判定値Ｋ２」となったことに伴い、減速時の燃料カット期間中に第１噴射弁２１によるガス燃料の噴射に切り替える場合、噴射周期を各気筒の１燃焼サイクルよりも長くして第１噴射弁２１によるガス燃料の噴射を実施する構成とした。減速時の燃料カット中では、増量可能な吸入空気量に制限があるため、通常運転時と同じように各気筒で所定位相毎に燃料噴射を実施すると燃料過多になるおそれがある。本構成によれば、ガス燃料の噴射による噴射圧の低下を図る際に、エミッションの悪化や触媒温度の過昇温が生じないようにすることができる。 When “injection pressure> decision value K2”, when switching to gas fuel injection by the first injection valve 21 during the fuel cut period during deceleration, the injection cycle is made longer than one combustion cycle of each cylinder. The first fuel injection valve 21 is configured to inject gas fuel. During fuel cut during deceleration, there is a limit to the amount of intake air that can be increased. Therefore, if fuel injection is performed for each predetermined phase in each cylinder as in normal operation, there is a risk of excessive fuel. According to this configuration, it is possible to prevent the deterioration of the emission and the excessive increase in the catalyst temperature when the injection pressure is reduced by the injection of the gas fuel.
　（第３実施形態）
　次に、本発明の第３実施形態について説明する。上記の第１実施形態では、第１噴射弁２１への供給ガス圧が判定値Ｋ１を超えた場合に、遮断制御弁を閉弁するとともに、エンジン負荷に応じて、第１噴射弁２１によるガス燃料の噴射を制限する構成とした。これに対し、本実施形態では、第１噴射弁２１への供給ガス圧が判定値Ｋ１を超えた場合に、遮断制御弁を閉弁するとともに、エンジン負荷に応じて、第１噴射弁２１から噴射されるガス燃料の消費を促進させる運転状態に変更する構成とする（運転切替手段）。 (Third embodiment)
Next, a third embodiment of the present invention will be described. In the first embodiment, when the supply gas pressure to the first injection valve 21 exceeds the determination value K1, the shutoff control valve is closed and the gas generated by the first injection valve 21 according to the engine load. The fuel injection is limited. On the other hand, in this embodiment, when the supply gas pressure to the first injection valve 21 exceeds the determination value K1, the shutoff control valve is closed and the first injection valve 21 is changed according to the engine load. It is set as the structure changed into the driving | running state which promotes consumption of the gas fuel injected (operation switching means).
　より具体的には、第１噴射弁２１への供給ガス圧が判定値Ｋ１を超えた場合に、遮断制御弁としてのタンク主止弁４４及び遮断弁４５を閉弁する。また、その時のエンジン負荷に応じて吸入空気量を増量補正するとともに、第１噴射弁２１によるガス燃料の噴射量を増量補正し、エンジン回転速度を上昇させる。この場合、第１噴射弁２１への供給ガス圧が判定値Ｋ１を超えた場合にもガス燃料の使用を継続することができる。また、第２噴射弁２２による液体燃料の噴射に切り替えなくて済むため、液体燃料の残存量が少ない場合にも供給ガス圧の高圧化に対処することが可能である。 More specifically, when the supply gas pressure to the first injection valve 21 exceeds the determination value K1, the tank main stop valve 44 and the cutoff valve 45 as the cutoff control valves are closed. In addition, the intake air amount is corrected to increase in accordance with the engine load at that time, and the injection amount of gas fuel from the first injection valve 21 is corrected to increase to increase the engine speed. In this case, the use of gas fuel can be continued even when the supply gas pressure to the first injection valve 21 exceeds the determination value K1. Further, since it is not necessary to switch to the injection of the liquid fuel by the second injection valve 22, it is possible to cope with the increase in the supply gas pressure even when the remaining amount of the liquid fuel is small.
　図１１は、本実施形態の燃料噴射制御の具体的態様を示すタイムチャートである。図１１では、ガス燃料の使用によるアイドル運転状態において、例えば圧力調整弁６０の弁座部６３に異物が噛み込み、噴射圧が判定値Ｋ１を超えた場合を想定している。なお、エンジン運転中であることから、噴射圧が判定値Ｋ１を超える前ではタンク主止弁４４及び遮断弁４５は開弁状態となっている。 FIG. 11 is a time chart showing a specific aspect of the fuel injection control of the present embodiment. In FIG. 11, it is assumed that, for example, a foreign matter is caught in the valve seat 63 of the pressure regulating valve 60 and the injection pressure exceeds the determination value K1 in an idle operation state using gas fuel. Since the engine is in operation, the tank main stop valve 44 and the shutoff valve 45 are open before the injection pressure exceeds the determination value K1.
　図１１において、噴射圧が判定値Ｋ１を超えると、そのタイミングｔ４１でタンク主止弁４４を閉弁し、続いて遮断弁４５を閉弁する。また、第１噴射弁２１の要求燃料量Ｑａを、第１噴射弁２１への供給ガス圧（噴射圧）に応じて定められる最小燃料量Ｑｍｉｎ又はそれよりも大きくなるように、吸入空気量及び燃料噴射量を増量補正する。なお、このとき、空燃比が理論空燃比又はそれよりもリーン状態になるように吸入空気量を補正する。これにより、エンジン回転速度がアイドル回転速度ＮＥ１（例えば、７００ｒｐｍ）よりも高くなり、その状態でエンジン１０の運転が継続される。またこのとき、タンク主止弁４４及び遮断弁４５は閉弁した状態のままであることから、第１噴射弁２１からのガス燃料の噴射によって噴射圧が低下する。 In FIG. 11, when the injection pressure exceeds the determination value K1, the tank main stop valve 44 is closed at the timing t41, and then the shutoff valve 45 is closed. Further, the amount of intake air and the required fuel amount Qa of the first injection valve 21 are set so as to become the minimum fuel amount Qmin determined according to the supply gas pressure (injection pressure) to the first injection valve 21 or higher. The fuel injection amount is corrected to increase. At this time, the intake air amount is corrected so that the air-fuel ratio becomes the stoichiometric air-fuel ratio or leaner than that. Thereby, the engine rotation speed becomes higher than the idle rotation speed NE1 (for example, 700 rpm), and the operation of the engine 10 is continued in this state. At this time, since the tank main stop valve 44 and the shutoff valve 45 remain closed, the injection pressure is reduced by the injection of gas fuel from the first injection valve 21.
　そして、噴射圧が判定値Ｋ３を下回ったタイミングｔ４２で遮断弁４５を開弁し、続いてタンク主止弁４４を開弁する。また、各弁４４、４５の開弁に伴い噴射圧が設定圧Ｐｒｅｇに調整された後において吸入空気量の増量補正を解除する。 Then, at the timing t42 when the injection pressure falls below the determination value K3, the shutoff valve 45 is opened, and then the tank main stop valve 44 is opened. Further, after the injection pressure is adjusted to the set pressure Preg as the valves 44 and 45 are opened, the increase correction of the intake air amount is cancelled.
　以上詳述した第３実施形態によれば、次の効果が得られる。 According to the third embodiment described in detail above, the following effects can be obtained.
　圧力調整弁６０では、閉弁状態で例えば異物等の噛み込みが生じることによって上流側から下流側へガス燃料がリークし、その燃料リークによって、下流側の燃料圧力、すなわち第１噴射弁２１へのガス燃料の供給圧力（噴射圧）が意図せずに高くなることが考えられる。また、第１噴射弁２１に対する供給圧力が高いと、その高圧状態に起因して内燃機関（エンジン１０）の低負荷状態において噴射燃料が過多になることが生じ得る。本構成では、噴射圧が所定値よりも高圧になった場合には、遮断制御弁を閉弁するとともに、内燃機関の運転負荷に応じて、第１噴射弁２１から噴射されるガス燃料の消費を促進させる運転状態に変更するため、噴射燃料が過多になることを抑制することができる。 In the pressure regulating valve 60, gas fuel leaks from the upstream side to the downstream side due to, for example, a foreign matter being caught in the valve closed state, and the fuel leak causes the downstream fuel pressure, that is, the first injection valve 21. It is conceivable that the gas fuel supply pressure (injection pressure) increases unintentionally. Moreover, if the supply pressure with respect to the 1st injection valve 21 is high, it may arise that injection fuel becomes excessive in the low load state of an internal combustion engine (engine 10) due to the high pressure state. In this configuration, when the injection pressure becomes higher than a predetermined value, the shutoff control valve is closed and the consumption of the gas fuel injected from the first injection valve 21 according to the operating load of the internal combustion engine. Therefore, it is possible to suppress the excessive amount of injected fuel.
　また、上記構成によれば、第１噴射弁２１への供給ガス圧が判定値Ｋ１を超えた場合にもガス燃料の使用を継続することができる。また更に、第２噴射弁２２による液体燃料の噴射に切り替えなくて済むため、液体燃料の残存量が少ない場合にも噴射圧の高圧化に対処することができる。 Further, according to the above configuration, the use of gas fuel can be continued even when the supply gas pressure to the first injection valve 21 exceeds the determination value K1. Furthermore, since it is not necessary to switch to the injection of the liquid fuel by the second injection valve 22, it is possible to cope with the increase in the injection pressure even when the remaining amount of the liquid fuel is small.
　（他の実施形態）
　本発明は上記実施形態の記載内容に限定されず、例えば次のように実施されてもよい。 (Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be implemented as follows, for example.
　上記実施形態では、遮断制御弁としてタンク主止弁４４及び遮断弁４５とを備え、噴射圧が判定値Ｋ１を超えた場合には、タンク主止弁４４及び遮断弁４５を閉弁状態にしたが、いずれか一方のみを制御対象としてもよい。例えば、上記図１の構成において、噴射圧が判定値Ｋ１を超えた場合には、遮断弁４５のみを閉弁状態にして、タンク主止弁４４については開弁した状態のままにしておく。この場合にもガスタンク４２から第１噴射弁２１へのガス燃料の供給を遮断できることから、上記と同様の効果を奏する。 In the above embodiment, the tank main stop valve 44 and the cutoff valve 45 are provided as the cutoff control valves, and when the injection pressure exceeds the determination value K1, the tank main stop valve 44 and the cutoff valve 45 are closed. However, only one of them may be controlled. For example, in the configuration shown in FIG. 1, when the injection pressure exceeds the determination value K1, only the shutoff valve 45 is closed and the tank main stop valve 44 is left open. Also in this case, since the supply of gas fuel from the gas tank 42 to the first injection valve 21 can be cut off, the same effects as described above are obtained.
　上記第１実施形態では、第１噴射弁２１への供給ガス圧が判定値Ｋ１を超えた場合に、遮断制御弁を閉弁するとともに、エンジン負荷に応じて第１噴射弁２１によるガス燃料の噴射を制限する構成とした。本実施形態では、第１噴射弁２１への供給ガス圧が判定値Ｋ１を超えた場合に、遮断制御弁の閉弁と共に実施する処理として、（１）エンジン負荷に応じて第１噴射弁２１によるガス燃料の噴射を制限する処理、及び（２）エンジン負荷に応じて、第１噴射弁２１から噴射されるガス燃料の消費を促進させる運転状態に変更する処理、のうちいずれの処理を実施するかを選択する（処理選択手段）。そして、（１）の処理を選択した場合には、上記図５のステップＳ１０４～Ｓ１０７と同様の処理を実行する。また、（２）の処理を選択した場合には、その時のエンジン負荷に応じて吸入空気量を増量補正するとともに第１噴射弁２１から噴射されるガス燃料量を増量補正し、エンジン回転速度を上昇させる処理を実行する。処理選択手段について具体的には、例えば液体燃料の残存量に基づいて選択し、液体燃料の残存量が所定値以上である場合には上記（１）の処理を選択し、該残存量が所定値を下回っている場合には上記（２）の処理を選択する構成としてもよい。 In the first embodiment, when the supply gas pressure to the first injection valve 21 exceeds the determination value K1, the shut-off control valve is closed and the gas fuel by the first injection valve 21 is changed according to the engine load. It was set as the structure which restrict | limits injection. In this embodiment, when the supply gas pressure to the 1st injection valve 21 exceeds determination value K1, as a process implemented with valve closing of a cutoff control valve, (1) 1st injection valve 21 according to engine load The process of restricting the injection of gas fuel by (1) and (2) the process of changing to the operating state that promotes the consumption of the gas fuel injected from the first injection valve 21 according to the engine load is performed. To select (process selection means). If the process (1) is selected, the same processes as in steps S104 to S107 in FIG. 5 are executed. When the process (2) is selected, the intake air amount is increased and corrected in accordance with the engine load at that time, and the gas fuel amount injected from the first injection valve 21 is increased and corrected. Execute the process to raise. Specifically, the process selection means is selected based on, for example, the remaining amount of liquid fuel. If the remaining amount of liquid fuel is equal to or greater than a predetermined value, the process (1) is selected, and the remaining amount is determined to be predetermined. When the value is lower than the value, the process (2) may be selected.
　噴射圧が判定値Ｋ１を超えたことに伴い遮断制御弁を閉弁するとともに、第１噴射弁２１によるガス燃料の使用を制限する処理を所定期間内に所定回数実施した場合に、レギュレータ４３の異常である旨の判定をする構成としてもよい。また、その異常判定がされた場合に運転者に通知する構成としてもよい。 When the process of limiting the use of gas fuel by the first injection valve 21 is performed a predetermined number of times within a predetermined period while the shutoff control valve is closed as the injection pressure exceeds the determination value K1, the regulator 43 It is good also as a structure which determines that it is abnormal. Moreover, it is good also as a structure which notifies a driver | operator when the abnormality determination is made.
　噴射圧が判定値Ｋ１又は判定値Ｋ２を超える状態が所定期間継続した場合に、レギュレータ４３の異常である旨の判定をする構成としてもよい。また、その異常判定がされた場合に運転者に通知する構成としてもよい。 It is good also as a structure which determines that it is abnormal of the regulator 43, when the state where the injection pressure exceeds the determination value K1 or the determination value K2 continues for a predetermined period. Moreover, it is good also as a structure which notifies a driver | operator when the abnormality determination is made.
　上記においてレギュレータ異常有りと判定した場合の処理として、遮断制御弁（タンク主止弁４４及び遮断弁４５）の駆動を制御することによって噴射圧を制御する退避走行処理を実施してもよい。この退避走行処理を実施する際、遮断弁４５を開弁した状態のままとして、タンク主止弁４４の開閉を制御することにより噴射圧を制御することが望ましい。燃料配管のより上流側に配置された遮断制御弁、すなわちタンク主止弁４４により噴射圧を制御することにより、下流側の遮断弁４５により噴射圧を制御する場合に比べて、第１噴射弁２１までの燃料配管の容積を大きくすることができ、弁の開閉に伴い生じる噴射圧の変動を抑制することが可能となる。これにより、噴射圧を安定して制御することができる。この退避走行処理の実施中では、スロットル開度を制限することにより、退避走行に必要な噴射圧を安定して維持することが望ましい。 As a process when it is determined that there is a regulator abnormality in the above, a retreat travel process for controlling the injection pressure by controlling the drive of the shutoff control valves (tank main stop valve 44 and shutoff valve 45) may be performed. When carrying out this retreat travel processing, it is desirable to control the injection pressure by controlling the opening and closing of the tank main stop valve 44 while keeping the shut-off valve 45 open. Compared to the case where the injection pressure is controlled by the cutoff valve 45 on the downstream side by controlling the injection pressure by the cutoff control valve arranged at the upstream side of the fuel pipe, that is, the tank main stop valve 44, the first injection valve. The volume of the fuel pipe up to 21 can be increased, and the fluctuation of the injection pressure caused by opening and closing of the valve can be suppressed. Thereby, injection pressure can be controlled stably. During the retreat travel process, it is desirable to stably maintain the injection pressure necessary for retreat travel by limiting the throttle opening.
　図５のステップＳ１１２では、第１噴射弁２１への供給ガス圧と判定値Ｋ３とを比較し、供給ガス圧が判定値Ｋ３を下回った場合に遮断制御弁としての遮断弁４５及びタンク主止弁４４を開弁駆動させる構成とした。判定値Ｋ３を用いる構成に代えて、例えば設定圧Ｐｒｅｇを用いる構成としてもよい。 In step S112 of FIG. 5, the supply gas pressure to the first injection valve 21 is compared with the determination value K3, and when the supply gas pressure falls below the determination value K3, the shutoff valve 45 and the tank main stop as the shutoff control valve. The valve 44 is driven to open. Instead of the configuration using the determination value K3, for example, a configuration using the set pressure Preg may be used.
　上記実施形態では、判定値Ｋ１～判定値Ｋ３を一定値としたが、例えばバッテリ電圧、エンジン冷却水温、吸気温、レギュレータ上流圧、ガス燃料温度等の少なくともいずれかに応じて可変にする構成としてもよい。 In the above embodiment, the determination value K1 to the determination value K3 are constant values. However, for example, the determination value K1 to the determination value K3 are variable according to at least one of battery voltage, engine cooling water temperature, intake air temperature, regulator upstream pressure, gas fuel temperature, and the like. Also good.
　上記実施形態では、多気筒エンジンの気筒ごとに第１噴射弁２１及び第２噴射弁２２をそれぞれ複数ずつ設ける構成としたが、複数の気筒の共通部分に第１噴射弁２１及び第２噴射弁２２のうちの少なくともいずれかを設ける構成としてもよい。例えば、吸気系統１１の集合部分に対してガス燃料や液体燃料を噴射する構成としてもよい。 In the above embodiment, a plurality of the first injection valves 21 and the second injection valves 22 are provided for each cylinder of the multi-cylinder engine. However, the first injection valve 21 and the second injection valve are provided in common portions of the plurality of cylinders. It is good also as a structure which provides at least any one of 22. For example, it is good also as a structure which injects gaseous fuel and liquid fuel with respect to the collection part of the intake system 11. FIG.
　上記実施形態ではガス燃料をＣＮＧ燃料としたが、標準状態で気体状態の他のガス燃料を用いることもできる。例えばメタン、エタン、プロパン、ブタン、水素、ＤＭＥなどを主成分とする燃料を用いる構成としてもよい。また、液体燃料についてもガソリン燃料に限らず、例えば軽油などを用いる構成としてもよい。 In the above embodiment, the gas fuel is CNG fuel, but other gas fuels in a gas state can be used in the standard state. For example, it is possible to use a fuel mainly composed of methane, ethane, propane, butane, hydrogen, DME, or the like. Further, the liquid fuel is not limited to gasoline fuel, and for example, light oil or the like may be used.

Claims (12)

  1. 　ガス燃料を噴射する第１噴射手段（２１）と、
    　液体燃料を噴射する第２噴射手段（２２）と、
    　前記ガス燃料を供給する燃料通路（４１）に設けられ、前記第１噴射手段に供給されるガス燃料の圧力を所定の設定圧力に減圧調整する圧力調整弁（６０）と、
    　前記燃料通路において前記圧力調整弁の上流側に設けられ、前記ガス燃料の流通を遮断する遮断機能を有する遮断制御弁（４４、４５）と、を備える燃料噴射システムに適用される燃料噴射制御装置であって、
    　前記第１噴射手段に供給されるガス燃料の圧力である供給圧力が、前記設定圧力よりも高圧側の所定の第１判定値（Ｋ１）を超えたか否かを判定する第１判定手段と、
    　前記第１判定手段により前記供給圧力が前記第１判定値を超えたことが判定された場合に、前記遮断制御弁を閉弁するとともに、前記内燃機関の運転負荷に応じて前記第１噴射手段によるガス燃料の噴射から前記第２噴射手段による液体燃料の噴射への切り替えを実施する燃料切替手段と、
    を備える内燃機関の燃料噴射制御装置。     First injection means (21) for injecting gaseous fuel;
    Second injection means (22) for injecting liquid fuel;
    A pressure adjustment valve (60) provided in a fuel passage (41) for supplying the gas fuel, and for reducing the pressure of the gas fuel supplied to the first injection means to a predetermined set pressure;
    A fuel injection control device applied to a fuel injection system, comprising a cutoff control valve (44, 45) provided on the upstream side of the pressure regulating valve in the fuel passage and having a cutoff function for blocking the flow of the gas fuel Because
    First determination means for determining whether or not a supply pressure, which is a pressure of gas fuel supplied to the first injection means, exceeds a predetermined first determination value (K1) on a higher pressure side than the set pressure;
    When it is determined by the first determination means that the supply pressure has exceeded the first determination value, the shutoff control valve is closed and the first injection means according to the operating load of the internal combustion engine Fuel switching means for performing switching from the injection of gas fuel by the second fuel injection by the second injection means;
    A fuel injection control device for an internal combustion engine.
  2. 　前記燃料切替手段は、前記第１噴射手段において噴射可能な燃料量の最小値として前記供給圧力に応じて定められる最小燃料量と、前記運転負荷に応じて定められる要求燃料量との比較結果に基づいて、前記第１噴射手段によるガス燃料の噴射から前記第２噴射手段による液体燃料の噴射に切り替える請求項１に記載の内燃機関の燃料噴射制御装置。 The fuel switching means is based on a comparison result between a minimum fuel amount determined according to the supply pressure as a minimum value of the fuel amount that can be injected by the first injection means and a required fuel amount determined according to the operating load. 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel injection control device switches from gas fuel injection by the first injection means to liquid fuel injection by the second injection means.
  3. 　前記燃料切替手段による前記液体燃料の噴射への切り替え後において前記要求燃料量が前記最小燃料量よりも大きくなった場合に、前記遮断制御弁を閉弁した状態のまま前記第２噴射手段による液体燃料の噴射から前記第１噴射手段によるガス燃料の噴射に切り替える請求項２に記載の内燃機関の燃料噴射制御装置。 When the required fuel amount becomes larger than the minimum fuel amount after the switching to the liquid fuel injection by the fuel switching unit, the liquid by the second injection unit with the shutoff control valve closed. The fuel injection control device for an internal combustion engine according to claim 2, wherein the fuel injection is switched from fuel injection to gas fuel injection by the first injection means.
  4. 　前記燃料切替手段による前記液体燃料の噴射への切り替え後において前記供給圧力が前記第１判定値よりも高圧側の所定の第２判定値を超えたか否かを判定する第２判定手段と、
    　前記第２判定手段により前記供給圧力が前記第２判定値を超えたことが判定された場合に、前記遮断制御弁を閉弁した状態のまま前記第２噴射手段による液体燃料の噴射から前記第１噴射手段によるガス燃料の噴射に切り替えるガス切替手段と、
    を備える請求項１乃至３のいずれか一項に記載の内燃機関の燃料噴射制御装置。     Second determination means for determining whether or not the supply pressure exceeds a predetermined second determination value on a higher pressure side than the first determination value after switching to the injection of the liquid fuel by the fuel switching means;
    When it is determined by the second determination means that the supply pressure exceeds the second determination value, the second fuel injection from the liquid fuel injection by the second injection means while the shutoff control valve is closed is performed. Gas switching means for switching to gas fuel injection by one injection means;
    A fuel injection control device for an internal combustion engine according to any one of claims 1 to 3.
  5. 　前記ガス切替手段により前記ガス燃料の噴射に切り替える場合に、前記第１噴射手段から噴射されるガス燃料の消費を促進させる運転状態に変更する運転変更手段を備える請求項４に記載の内燃機関の燃料噴射制御装置。 5. The internal combustion engine according to claim 4, further comprising an operation changing unit that changes to an operation state that promotes consumption of the gas fuel injected from the first injection unit when the gas switching unit switches to the injection of the gas fuel. Fuel injection control device.
  6. 　前記内燃機関の吸入空気量を調整する空気量調整手段（１５）を備え、
    　前記運転変更手段は、前記ガス切替手段により前記ガス燃料の噴射に切り替える場合に、前記空気量調整手段により前記吸入空気量を増量補正することにより、前記ガス燃料の消費を促進させる運転状態に変更する請求項５に記載の内燃機関の燃料噴射制御装置。     An air amount adjusting means (15) for adjusting an intake air amount of the internal combustion engine;
    The operation change means changes to an operation state that promotes consumption of the gas fuel by correcting the increase in the intake air amount by the air amount adjustment means when the gas switching means switches to the injection of the gas fuel. The fuel injection control device for an internal combustion engine according to claim 5.
  7. 　前記運転変更手段は、前記吸入空気量を増量補正する場合に前記内燃機関の点火時期を遅角側に変更する請求項６に記載の内燃機関の燃料噴射制御装置。 The fuel injection control device for an internal combustion engine according to claim 6, wherein the operation changing means changes the ignition timing of the internal combustion engine to a retard side when the intake air amount is corrected to be increased.
  8. 　前記ガス切替手段による前記ガス燃料の噴射への切り替え後において前記供給圧力が前記設定圧力よりも低圧側の所定の第３判定値を下回ったか否かを判定する第３判定手段を備え、
    　前記第３判定手段により前記供給圧力が前記第３判定値を下回ったことが判定された場合に前記遮断制御弁を開弁する請求項４乃至７のいずれか一項に記載の内燃機関の燃料噴射制御装置。     A third determination unit that determines whether or not the supply pressure is lower than a predetermined third determination value on a lower pressure side than the set pressure after the gas switching unit switches to the injection of the gas fuel;
    The fuel for an internal combustion engine according to any one of claims 4 to 7, wherein the shutoff control valve is opened when the third determination means determines that the supply pressure is lower than the third determination value. Injection control device.
  9. 　減速時の燃料カットを実施する所定の燃料カット条件が成立しているか否かを判定する条件判定手段を備え、
    　前記ガス切替手段は、前記第２判定手段により前記供給圧力が前記第２判定値を超えたことが判定された場合であって、かつ前記条件判定手段により前記燃料カット条件が成立していることが判定された場合に、前記遮断制御弁を閉弁した状態のまま前記第２噴射手段による液体燃料の噴射から前記第１噴射手段によるガス燃料の噴射に切り替える請求項４乃至８のいずれか一項に記載の内燃機関の燃料噴射制御装置。     Condition determining means for determining whether or not a predetermined fuel cut condition for performing fuel cut at the time of deceleration is satisfied,
    The gas switching means is a case where it is determined by the second determination means that the supply pressure has exceeded the second determination value, and the fuel cut condition is satisfied by the condition determination means. When the determination is made, the liquid fuel injection by the second injection means is switched to the gas fuel injection by the first injection means while the shutoff control valve is closed. A fuel injection control device for an internal combustion engine according to the item.
  10. 　前記ガス切替手段による前記ガス燃料の噴射への切り替え後において、前記第１噴射手段によるガス燃料の噴射周期を前記内燃機関の１燃焼サイクルよりも長くして前記ガス燃料の噴射を実施する請求項９に記載の内燃機関の燃料噴射制御装置。 The gas fuel injection is performed by setting the gas fuel injection period of the first injection means to be longer than one combustion cycle of the internal combustion engine after the gas switching means switches to the injection of the gas fuel. A fuel injection control device for an internal combustion engine according to claim 9.
  11. 　前記第１判定手段により前記供給圧力が前記判定値を超えたことが判定された場合に、前記遮断制御弁を閉弁するとともに、前記内燃機関の運転負荷に応じて、前記第１噴射手段から噴射されるガス燃料の消費を促進させる運転状態に変更する運転切替手段を備え、
    　前記第１判定手段により前記供給圧力が前記第１判定値を超えたことが判定された場合に、前記燃料切替手段により前記液体燃料の噴射に切り替える処理及び前記運転切替手段により前記ガス燃料の消費を促進させる運転状態に変更する処理のうちいずれを実施するかを選択し、該選択した処理を実施する請求項１乃至１０のいずれか一項に記載の内燃機関の燃料噴射制御装置。     When it is determined by the first determination means that the supply pressure has exceeded the determination value, the shutoff control valve is closed, and the first injection means is operated according to the operating load of the internal combustion engine. Comprising an operation switching means for changing to an operation state that promotes the consumption of injected gas fuel,
    When the first determining means determines that the supply pressure has exceeded the first determination value, the fuel switching means switches to the liquid fuel injection and the operation switching means consumes the gas fuel. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 10, wherein which of the processes to change to the operating state that promotes the operation is selected and the selected process is performed.
  12. 　ガス燃料を噴射する第１噴射手段（２１）と、
    　液体燃料を噴射する第２噴射手段（２２）と、
    　前記ガス燃料を供給する燃料通路（４１）に設けられ、前記第１噴射手段に供給されるガス燃料の圧力を所定の設定圧力に減圧調整する圧力調整弁（６０）と、
    　前記燃料通路において前記圧力調整弁の上流側に設けられ、前記ガス燃料の流通を遮断する遮断機能を有する遮断制御弁（４４、４５）と、を備える燃料噴射システムに適用される燃料噴射制御装置であって、
    　前記第１噴射手段に供給されるガス燃料の圧力である供給圧力が、前記設定圧力よりも高圧側の所定の判定値（Ｋ１）を超えたか否かを判定する判定手段と、
    　前記判定手段により前記供給圧力が前記判定値を超えたことが判定された場合に、前記遮断制御弁を閉弁するとともに、前記内燃機関の運転負荷に応じて、前記第１噴射手段から噴射されるガス燃料の消費を促進させる運転状態に変更する運転切替手段と、
    を備えることを特徴とする内燃機関の燃料噴射制御装置。     First injection means (21) for injecting gaseous fuel;
    Second injection means (22) for injecting liquid fuel;
    A pressure adjustment valve (60) provided in a fuel passage (41) for supplying the gas fuel, and for reducing the pressure of the gas fuel supplied to the first injection means to a predetermined set pressure;
    A fuel injection control device applied to a fuel injection system, comprising a cutoff control valve (44, 45) provided on the upstream side of the pressure regulating valve in the fuel passage and having a cutoff function for blocking the flow of the gas fuel Because
    Determination means for determining whether or not a supply pressure, which is a pressure of the gas fuel supplied to the first injection means, exceeds a predetermined determination value (K1) on the higher pressure side than the set pressure;
    When the determination means determines that the supply pressure has exceeded the determination value, the shutoff control valve is closed and injected from the first injection means according to the operating load of the internal combustion engine. Operation switching means for changing to an operating state that promotes consumption of gas fuel;
    A fuel injection control device for an internal combustion engine, comprising:
PCT/JP2013/006770 2012-12-13 2013-11-19 Fuel injection control device for internal combustion engine WO2014091678A1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108825410A (en) * 2018-05-25 2018-11-16 哈尔滨工程大学 A kind of shunt fuel gas ejecting device and its exhaust gas nozzle
CN109268164A (en) * 2018-07-24 2019-01-25 哈尔滨工程大学 A kind of natural gas engine burning tissues method and device

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6353709B2 (en) 2014-06-09 2018-07-04 矢崎総業株式会社 Backup signal generation circuit for load control
US11092091B2 (en) * 2018-03-19 2021-08-17 Woodward, Inc. Pressure regulating mass flow system for multipoint gaseous fuel injection

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011163155A (en) * 2010-02-05 2011-08-25 Keihin Corp Fuel switching control device and method
WO2012073356A1 (en) * 2010-12-01 2012-06-07 トヨタ自動車 株式会社 Device for controlling bi-fuel engine

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011163155A (en) * 2010-02-05 2011-08-25 Keihin Corp Fuel switching control device and method
WO2012073356A1 (en) * 2010-12-01 2012-06-07 トヨタ自動車 株式会社 Device for controlling bi-fuel engine

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108825410A (en) * 2018-05-25 2018-11-16 哈尔滨工程大学 A kind of shunt fuel gas ejecting device and its exhaust gas nozzle
CN109268164A (en) * 2018-07-24 2019-01-25 哈尔滨工程大学 A kind of natural gas engine burning tissues method and device

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