JP2005163668A - Internal combustion engine and operating method for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine and an operating method for the internal combustion engine, capable of suppressing increase in an addition ratio of hydrogen to gasoline, of reducing NO<SB>x</SB>concentration of exhaust gas discharged to the atmosphere only by a three way catalyst, and of enhancing efficiency of the internal combustion engine. <P>SOLUTION: The engine 1 is equipped with a liquid fuel supply device 2 for supplying liquid fuel to the engine 1, a hydrogen supply device 3 for supplying hydrogen to the engine 1, an EGR device 4 for recirculating exhaust gas discharged to an exhaust system 5 of the engine 1 through an intake system 8, and the three way catalyst 51 for purifying exhaust gas in the exhaust system 5. When exhaust gas is recirculated through the intake system 8, gasoline and hydrogen are supplied to the engine 1, and the engine 1 is operated such that an air fuel ratio of gasoline and hydrogen to air sucked from the intake system 8 becomes a theoretical air fuel ratio. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine and an internal combustion engine operation method, and more particularly to an internal combustion engine that supplies liquid fuel and hydrogen to the internal combustion engine and an internal combustion engine operation method.

A gasoline engine, which is an internal combustion engine mounted on a general passenger car, has an air-fuel ratio of the theoretical air-fuel ratio (λ = 1) between gasoline, which is liquid fuel supplied to the engine, and air sucked from the intake system of the engine. It will be driven to become. When the engine is operated at the stoichiometric air-fuel ratio, most of harmful substances (CO ₂ , HC, NO _x ) contained in the exhaust gas discharged to the exhaust system of the engine can be purified only by the three-way catalyst. Therefore, no other catalyst such as a NO _x storage catalyst is required. However, in the above-described engine, in order to operate the air-fuel ratio between gasoline and air at the stoichiometric air-fuel ratio (λ = 1), the throttle valve that adjusts the amount of air taken in from the intake system of the engine is fully opened. However, there is a problem that a pump loss occurs due to the throttle valve being closed with respect to the fully opened state, thereby hindering high efficiency of the engine.

Therefore, as a method of reducing the pump loss, it is conceivable that the engine is operated in a state where the air-fuel ratio between gasoline and air is higher than the theoretical air-fuel ratio (λ> 1) by first opening the throttle valve. That is, high efficiency is achieved by operating the engine with lean combustion of gasoline in the combustion chamber of the engine. However, gasoline has a problem that its combustible range is narrow and its ignitability is low, so that it cannot perform lean combustion to the extent that high efficiency of the engine can be achieved. Further, when the engine is operated in a state higher than the stoichiometric air-fuel ratio (λ> 1), that is, when gasoline is lean burned, the NO _x concentration of the exhaust gas discharged to the engine exhaust system becomes high. Therefore, by operating the engine at a stoichiometric air-fuel ratio, it is possible to purify NO _x contained in the exhaust gas to such an extent that it can be discharged into the atmosphere with only a three-way catalyst that purifies the harmful substances in the exhaust gas. There is also a problem that a new NO _x storage catalyst is required.

It is also conceivable to recirculate the exhaust gas of the engine exhaust system to the intake system. Recirculating the exhaust gas to the engine intake system reduces the amount of air that is drawn into the engine intake system. Therefore, in order to operate the engine at a stoichiometric air-fuel ratio of gasoline and air, it is necessary to open the throttle valve, thereby reducing pump loss and increasing efficiency. In addition, because the exhaust gas recirculated to the engine intake system has a large heat capacity, the combustion gas is burned when the mixture of gasoline and air is combusted in the combustion chamber of the engine. The temperature drops. In general, when the combustion temperature of the combustion gas decreases, the generation of NO _x can be reduced, so that the NO _x concentration in the exhaust gas can be lowered. However, if a large amount of exhaust gas is recirculated through the intake system of the engine, the combustion of the mixture of gasoline and air in the combustion chamber will deteriorate. Therefore, the amount of exhaust gas recirculated to the intake system of the engine cannot be increased, and it has been difficult to reduce pump loss and increase the efficiency of the engine.

  Therefore, conventionally, gasoline and hydrogen, which are liquid fuels, are supplied to the engine, that is, hydrogen is added to the gasoline, and the mixture of gasoline, hydrogen, and air is diluted in the combustion chamber of the engine, and this engine is operated. Techniques to do this have been proposed. Here, hydrogen has a wider flammable range and higher ignitability than liquid fuel such as gasoline. Therefore, the throttle valve is opened, the amount of air taken into the engine intake system is increased, and the engine is operated in a state where the air-fuel ratio between gasoline and added hydrogen and air is higher than the theoretical air-fuel ratio (λ> 1). can do. As a result, pump loss can be reduced, and the efficiency of the engine can be increased.

JP-A-3-26835

By the way, in the above conventional example, in order to reduce the pump loss, it is necessary to operate the engine with the air-fuel ratio of gasoline and added hydrogen and air higher than the theoretical air-fuel ratio (λ> 1). Therefore, even if purifying exhaust gas discharged by the three-way catalyst in an exhaust system of the engine, it is impossible to lower the concentration of NO _x in the exhaust gas after being purified by the three-way catalyst, newly _the NO _x storage There is a problem that a catalyst is required. Further, in order to lower the concentration of NO _x to the extent there is no need to purify the exhaust gas discharged to an exhaust system of the engine by the three-way catalyst and _the NO _x storage catalyst, increase hydrogen to be added to gasoline, that for gasoline It is necessary to increase the rate of hydrogen addition and burn on the lean burn side. Therefore, there is a problem that the amount of hydrogen required for engine operation increases.

The present invention was made in view of the above, it can be suppressed to increase the proportion of the added hydrogen to the liquid fuel, to reduce the concentration of NO _x in the exhaust gas discharged into the atmosphere only in the three-way catalyst An object of the present invention is to provide an internal combustion engine and an operation method of the internal combustion engine that can improve the efficiency of the internal combustion engine.

  In order to solve the above-described problems and achieve the object, according to the present invention, liquid fuel supply means for supplying the liquid fuel in the liquid fuel tank to the internal combustion engine, and hydrogen stored in the hydrogen storage portion are supplied to the internal combustion engine. An internal combustion engine comprising: a hydrogen supply means for exhausting; an exhaust gas recirculation means for recirculating exhaust gas discharged to an exhaust system of the internal combustion engine to an intake system of the internal combustion engine; and a three-way catalyst for purifying the exhaust gas of the exhaust system When the exhaust gas is recirculated to the intake system of the internal combustion engine, liquid fuel and hydrogen are supplied to the internal combustion engine, and the air-fuel ratio between the liquid fuel and hydrogen and the air taken in from the intake system is increased. And operating at a stoichiometric air-fuel ratio.

Further, in this invention, in the internal combustion engine, further comprising a concentration of NO _x detection means for detecting the concentration of NO _x in the exhaust gas to the exhaust system, based on the concentration of NO _x, the hydrogen to the liquid fuel supplied to the internal combustion engine It is characterized by changing the addition ratio.

According to the present invention, in the internal combustion engine, the addition ratio of hydrogen to the liquid fuel is an addition ratio at which the NO _x concentration of the exhaust gas is equal to or less than the NO _x concentration that can be purified by the three-way catalyst.

  According to the present invention, in the internal combustion engine, the hydrogen supply means further includes a residual hydrogen amount detection means for detecting a residual hydrogen amount in the hydrogen reservoir, and changes a hydrogen addition ratio with respect to the liquid fuel based on the residual hydrogen amount. It is characterized by making it.

  Further, according to the present invention, when the residual hydrogen amount is exhausted, only the liquid fuel is supplied to the internal combustion engine, and the recirculation of the exhaust gas to the intake system of the internal combustion engine is stopped, so that the liquid fuel and the air The operation is performed such that the air-fuel ratio becomes the stoichiometric air-fuel ratio.

  Further, in the present invention, the hydrogen supply means includes a passage pressure detecting means for detecting a passage pressure of the hydrogen supply passage to a hydrogen supply passage that connects the hydrogen reservoir to a hydrogen injection valve that supplies hydrogen to the internal combustion engine. And a shutoff valve for shutting off hydrogen supplied from the hydrogen reservoir to the hydrogen injection valve, and shutting off the supply of liquid fuel and hydrogen to the internal combustion engine closes the shutoff valve and stops the supply of hydrogen. At the same time, the recirculation of the exhaust gas to the intake system of the internal combustion engine is stopped, and the supply of the liquid fuel is stopped when the pressure in the passage becomes equal to or lower than the specified pressure.

  Further, in the present invention, at least one of liquid fuel and hydrogen is supplied to the internal combustion engine, the exhaust gas of the exhaust system of the internal combustion engine is recirculated to the intake system of the internal combustion engine, and the exhaust gas of the exhaust system is recirculated. A method of operating an internal combustion engine that purifies with a three-way catalyst, wherein when exhaust gas is recirculated to an intake system of the internal combustion engine, liquid fuel and hydrogen are supplied to the internal combustion engine, and the liquid fuel and hydrogen, and the intake system The air-fuel ratio with respect to the air sucked from the engine is operated so as to be the stoichiometric air-fuel ratio.

In the internal combustion engine and the operation method of the internal combustion engine according to the present invention, when exhaust gas is recirculated to the intake system of the internal combustion engine, liquid fuel and hydrogen are supplied to the internal combustion engine. However, stable combustion of a mixture of liquid fuel and hydrogen and air taken in from the intake system can be performed. Further, by recirculating the exhaust gas in a large amount, it is possible to suppress an increase in the ratio of hydrogen added to the liquid fuel, and to reduce the NO _x concentration of the exhaust gas discharged to the exhaust system. Also, a liquid fuel and hydrogen, the air-fuel ratio of the air taken from the intake system is so operated as a stoichiometric air-fuel ratio, a low concentration of NO _x discharged into the exhaust system the exhaust gas only a three-way catalyst Thus, it is possible to purify to the extent that it can be discharged to the atmosphere, and no other catalyst such as a NO _x storage catalyst is required, and the manufacturing cost of the internal combustion engine can be reduced. Further, since the amount of air taken in from the intake system is reduced by exhaust gas recirculated in a large amount, the internal combustion engine is operated so that the air-fuel ratio of liquid fuel, hydrogen, and air becomes the stoichiometric air-fuel ratio. Needs to open a throttle valve that adjusts the amount of air taken from the intake system. As a result, the pump loss can be reduced, and the efficiency of the internal combustion engine can be increased.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the best mode for carrying out the invention. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. Here, in the following embodiment, a gasoline engine mounted on a vehicle such as a passenger car or a truck will be described as an internal combustion engine. However, the present invention is not limited to this and can be applied to a diesel engine or the like. . Although the case where gasoline is used as the liquid fuel to be supplied to the internal combustion engine will be described, the present invention is not limited to this. Light oil, liquefied natural gas (LNG), liquefied petroleum gas (LPG), etc. are used as the liquid fuel. The present invention can also be applied to an internal combustion engine that supplies fuel.

  FIG. 1 is a diagram illustrating a configuration example of an engine (internal combustion engine) according to the first embodiment. As shown in FIG. 1, an engine 1 that is an internal combustion engine includes a liquid fuel supply device 2 that is liquid fuel supply means, a hydrogen supply device 3 that is hydrogen supply means, and an EGR device 4 that is exhaust gas recirculation means. The three-way catalyst 51 is provided in the exhaust system 5 of the engine 1. Reference numeral 6 denotes each cylinder of the engine 1, 7 denotes an ECU (Engine Control Unit) that is an operation control device that controls the operation of the engine 1, and 8 denotes an intake system of the engine 1.

  The liquid fuel supply device 2 that is a liquid fuel supply means supplies gasoline that is liquid fuel in a liquid fuel tank (not shown) to the engine 1 that is an internal combustion engine. The liquid fuel supply device 2 includes a liquid fuel tank (not shown), a low pressure pump (not shown), a high pressure pump 21, and a liquid fuel injection valve 22. Gasoline stored in a liquid fuel tank (not shown) is pressurized by a low-pressure pump driven by a low-pressure pump drive signal from the ECU 7 and is pumped to the high-pressure pump 21. The high pressure pump 21 is provided with at least a solenoid valve, a pressurizing chamber, and a plunger (not shown). The pressurized gasoline pumped to the high-pressure pump 21 is supplied to the pressurizing chamber from an electromagnetic valve whose valve opening degree is controlled by an electromagnetic valve opening / closing signal from the ECU 7. The gasoline supplied to the pressurizing chamber is further pressurized by a plunger that moves up and down by the rotational force of a crankshaft (not shown) and is pumped to the liquid fuel injection valve 22. The liquid fuel injection valve 22 injects gasoline pumped from the high-pressure pump 21 into an intake passage 81 of an intake system 8 of the engine 1 to be described later. An injection timing and an injection amount are determined by a liquid fuel injection signal from the ECU 7. Is controlled.

  A hydrogen supply device 3 that is a hydrogen supply means supplies hydrogen stored in a hydrogen tank 31 that is a hydrogen storage unit to an engine 1 that is an internal combustion engine. The hydrogen supply device 3 includes a hydrogen tank 31 that is a hydrogen storage unit that stores liquid hydrogen, a hydrogen pump 32, a hydrogen injection valve 33 that supplies hydrogen to the engine 1 that is an internal combustion engine, and hydrogen injection from the hydrogen tank 31. It is constituted by a hydrogen supply passage 34 connecting up to the valve 33. The liquid hydrogen stored in the hydrogen tank 31 is supplied to the hydrogen fuel injection valve 33 via the hydrogen supply passage 34 by a hydrogen pump 32 driven by a hydrogen pump drive signal from the ECU 7. Here, the hydrogen that is liquid in the hydrogen tank 31 flows into the hydrogen supply passage 34 to become a gas. The hydrogen injection valve 33 injects the hydrogen supplied from the hydrogen pump 32 into the intake passage 81 of the intake system 8 of the engine 1 described later. The injection amount based on the addition ratio with respect to gasoline is controlled.

  Reference numeral 35 denotes a tank internal pressure sensor which is a residual hydrogen amount detecting means for detecting the residual hydrogen amount in the hydrogen tank 31 which is a hydrogen storage unit and outputting the residual hydrogen amount to the ECU 7. The hydrogen tank 31 is not limited to one that directly stores liquid hydrogen. For example, a hydrogen storage alloy capable of storing hydrogen may be disposed in the hydrogen tank 31, or a fuel such as gasoline may be reformed. The hydrogen produced by doing so may be stored as a gas. The liquid fuel supply device 2 and the hydrogen supply device 3 both inject gasoline and hydrogen into the intake passage 81 of the intake system 8 of the engine 1, but the present invention is not limited to this, and gasoline or hydrogen It is good also as a structure which injects directly into the combustion chamber A formed in each cylinder 6 of the engine 1 mentioned later at least any one of these.

  The EGR device 4 as exhaust gas recirculation means recirculates the exhaust gas discharged to the exhaust system 5 of the engine 1 that is an internal combustion engine to the intake system 8 of the engine 1. The EGR device 4 includes an EGR valve 41 and an EGR passage 42. The EGR valve 41 changes its opening degree by a servo motor (not shown) or a magnetic force, and controls the recirculation amount of exhaust gas by an EGR valve opening / closing signal from the ECU 7. The exhaust gas flowing into the EGR passage 42 communicating with the exhaust passage 52 of the exhaust system 5 of the engine 1 is adjusted in recirculation amount by the EGR valve 41, and the throttle valve 84 of the intake passage 81 of the intake system 8 of the engine 1 described later. It flows in more upstream.

The exhaust system 5 includes a three-way catalyst 51, an exhaust passage 52, and a silencer (not shown). Exhaust gas discharged from an exhaust port 67 of each cylinder 6 of the engine 1 to be described later flows into the three-way catalyst 51 through the exhaust passage 52. The three-way catalyst 51 has an air-fuel ratio of gasoline or gasoline and hydrogen supplied to the combustion chamber A of each cylinder 6 by the engine 1 and air taken into the combustion chamber A of each cylinder 6 from the intake system 8 of the engine 1. By operating at a stoichiometric air-fuel ratio, harmful substances (CO ₂ , HC, NO _x ) contained in the exhaust gas can be purified without using other catalysts. The exhaust gas purified by the three-way catalyst 51 is discharged to the atmosphere through a silencer (not shown). Incidentally, 53 is a concentration of NO _x sensor detects the concentration of NO _x exhaust gas discharged, a concentration of NO _x detection means for outputting a concentration of NO _x in the exhaust gas to ECU7 from the exhaust port 67 of each cylinder 6 is there. Further, 54 detects the O ₂ concentration of the exhaust gas flowing into the three-way catalyst 51, an O ₂ concentration sensor is a O ₂ concentration detection means for outputting a O ₂ concentration in the exhaust gas to the ECU 7.

  Each cylinder 6 of the engine 1 includes a cylinder block 61, a piston 62, a cylinder head 63 fixed to the cylinder block 61, an intake valve 64, an exhaust valve 65, an intake port 66, an exhaust port 67, ignition. A plug 68 is used. Here, a combustion chamber A is formed between the piston 62 and the cylinder head 63. The spark plug 68 is ignited by an ignition signal from the ECU 7. Gasoline or gasoline and hydrogen injected into the intake passage 81 of the intake system 8 of the engine 1 and air taken into the intake passage 81 via an air cleaner 82 described later open the intake valve 64 of each cylinder 6. And flows into the combustion chamber A. Reference numeral 69 denotes a combustion chamber pressure sensor which is a combustion chamber pressure means for detecting the pressure in the combustion chamber A and outputting the pressure in the combustion chamber A to the ECU 7.

The ECU 7, which is an operation control device for the internal combustion engine, controls the operation of the engine 1. The ECU 7 includes sensors attached to various parts of the engine 1, for example, an angle sensor that detects an engine speed attached to a crankshaft (not shown), an accelerator opening sensor (not shown) that detects an accelerator opening, an in-tank pressure sensor 35, From the NO _x concentration detection sensor 53, the O ₂ concentration detection sensor 54, the combustion chamber pressure sensor 69, the air flow meter 83 of the intake system 8 of the engine 1 to be described later, and the like, the engine speed, the accelerator opening, the residual hydrogen amount, and the exhaust gas The NO _x concentration, the exhaust gas O ₂ concentration, the pressure in the combustion chamber, the amount of air, etc. are input as input signals. Further, based on this input signal and various maps stored in the storage unit 73, the injection control of the liquid fuel injection valve 22 and the hydrogen injection valve 33, the drive control of the low-pressure pump and the hydrogen pump 32 (not shown), and the high-pressure pump 21 An output signal for performing opening / closing control of a solenoid valve and EGR valve 41 (not shown) and a throttle valve of an intake system 8 of the engine 1 to be described later, ignition control of the spark plug 68, and the like is output.

  Specifically, an interface unit 71 that inputs and outputs the input signal and output signal, and a processing unit that calculates the injection timing and injection amount of the liquid fuel injection valve 22 and the hydrogen injection valve 33, the valve opening of the EGR valve, and the like. 72 and a storage unit 73 for storing the map and the like. The processing unit 72 includes a memory and a CPU (Central Processing Unit), and implements an operation method of the engine 1 by loading a program based on an operation method of the engine 1 that is an internal combustion engine into the memory and executing the program. It may be a thing. The storage unit 73 is a non-volatile memory such as a flash memory, a volatile memory such as a ROM (Read Only Memory) or a volatile memory such as a RAM (Random Access Memory) that can be read and written. The memory can be configured by a combination of these.

  The intake system 8 of the engine 1 is for causing the combustion chamber A of each cylinder 6 to intake air from the outside of the engine 1. The intake system 8 includes an intake passage 81, an air cleaner 82, an air flow meter 83, and a throttle valve 84. The air cleaner 82 removes impurities contained in air that is the atmosphere outside the engine 1. The air flow meter 83 detects the amount of air taken into the combustion chamber A from the intake port 66 of each cylinder 6 and outputs the amount of air taken into the engine 1 to the ECU 7. The throttle valve 84 changes its valve opening degree by a servo motor (not shown) or magnetic force, and the exhaust gas recirculated to the intake passage 81 of the intake system 8 by the EGR device 4 in response to a throttle valve opening / closing signal from the ECU 7. At the same time, the amount of air taken into the combustion chamber A is controlled. The intake valve 66 of each cylinder 6 is opened, and the air from which impurities are removed via the air cleaner 82 due to the negative pressure generated in the combustion chamber A is adjusted by the throttle valve 84, and the air of each cylinder 6 is adjusted. The air is taken into the combustion chamber A from the intake port 66.

Next, a method for operating the engine 1 that is an internal combustion engine will be described. FIG. 2 is a diagram illustrating an operation flow of the engine according to the first embodiment. FIG. 3A is a diagram illustrating a relationship between a fuel consumption rate and G / F. FIG. 3-2 is a diagram showing a relationship between the NO _x amount in the exhaust gas discharged to the exhaust system and G / F. Here, the fuel consumption rate means the amount of fuel (a combination of gasoline and hydrogen, which are liquid fuels) required for the output per unit time of the engine. G / F refers to a mass ratio between gas (including air and recirculated exhaust gas) sucked into the combustion chamber A of each cylinder 6 and gasoline and hydrogen as liquid fuel (hereinafter, referred to as G / F). The same). Here, the lower the value of the fuel consumption rate, the better the fuel consumption. G / F is the same as A / F when the exhaust gas is not recirculated.

  First, as shown in FIG. 2, the processing unit 72 of the ECU 7 inputs an angle sensor and an accelerator opening sensor (not shown), an engine speed, an accelerator opening, and an air amount output from the air flow meter 83 (step ST1). . Next, based on the normal addition ratio map, the processing unit 72 adds the gasoline injection amount injected from the liquid fuel injection means 22, the hydrogen addition ratio to the gasoline, and the exhaust gas recirculation amount recirculated to the intake system 8. Based on the above, the valve opening of the EGR valve 41, the valve opening of the throttle valve 84, and the ignition timing of the spark plug 68 are calculated (step ST2). This is based on a normal addition ratio map that is a map of the engine speed and the accelerator opening (not shown) stored in the storage unit 73, and an input signal of the engine speed and the accelerator opening that is input to the ECU 7 as an input signal. To be determined. Here, the normal addition ratio map used by the processing unit 72 is one of the maps stored in the storage unit 73, and the engine 1 is obtained by adding the hydrogen addition ratio to gasoline in a normal manner (about 20 to 30%). It is a map used when driving. Note that when the exhaust gas is recirculated to the intake system 8, the amount of air taken into the intake system 8 decreases. Therefore, the valve opening degree of the throttle valve 84 is calculated based on the air-fuel ratio of gasoline, hydrogen, and air. The air fuel consumption (λ = 1) is achieved.

  Next, the processing unit 72 calculates the air / fuel ratio of gasoline, hydrogen, and air based on the calculated theoretical fuel injection amount, hydrogen addition ratio, EGR valve opening, throttle valve opening, and ignition timing. The engine 1 is operated with fuel consumption (λ = 1) (step ST3). Specifically, the processing unit 72 outputs a liquid fuel injection signal to the liquid combustion injection valve 22 and is calculated at a predetermined injection timing from the liquid fuel injection valve 22 in the intake passage 81 of the intake system 8. Inject an amount of gasoline. Further, the processing unit 72 calculates the injection amount of hydrogen injected by the hydrogen injection valve 33 based on the hydrogen addition ratio with respect to gasoline, and outputs a hydrogen injection signal to the hydrogen injection valve 33, whereby the intake system 8. An injection amount of hydrogen calculated at a predetermined injection timing is injected from the hydrogen injection valve 33 into the intake passage 81. Here, gasoline, which is a liquid fuel, is supplied to the engine 1 as a liquid, whereas hydrogen is supplied to the engine 1 as a gas. Therefore, the calculation of the hydrogen injection amount based on the addition ratio of hydrogen to gasoline is: This is based on the calorific value of gasoline and hydrogen.

  Further, the processing unit 72 outputs an EGR valve opening / closing signal to the EGR valve 41, thereby opening the EGR valve 41 to a valve opening based on the calculated exhaust gas recirculation amount, and an intake passage 81 of the intake system 8. The exhaust gas is recirculated inside. Further, the processing unit 72 outputs a throttle valve opening / closing signal to the throttle valve 84, thereby opening the throttle valve 84 to the calculated valve opening and sucking air into the intake passage 81 of the intake system 8. When the intake valve 64 of each cylinder 6 is opened, gasoline, hydrogen, recirculated exhaust gas, and air are taken into the combustion chamber A of each cylinder 6 from the intake system 8. As a result, the combustion chamber A is filled with an air-fuel mixture in which the air-fuel ratio of gasoline and hydrogen and air is the stoichiometric air-fuel ratio (λ = 1). The processing unit 72 then ignites the spark plug 68 by outputting an ignition signal to the spark plug 68. When the spark plug 68 is ignited, the air-fuel mixture in the fuel chamber A is ignited to become combustion gas, and the piston 62 is pushed down to give a rotational force to a crankshaft (not shown) that is rotatably connected via a connecting rod (not shown). .

  As described above, the engine 1 is operated with the air-fuel ratio of gasoline, hydrogen and air as the theoretical air-fuel ratio (λ = 1). In the engine 1 which is the internal combustion engine of the first embodiment, when exhaust gas is recirculated to the intake system 8 of the engine 1, gasoline and hydrogen as liquid fuel are supplied to the engine 1. Even with recirculation, stable combustion of gasoline and a mixture of hydrogen and air can be performed.

  Next, a comparison between the engine 1 that is the internal combustion engine according to the first embodiment and the engine that performs lean combustion by adding hydrogen to the gasoline that is the conventional example will be described. In the conventional engine shown in FIG. 3C, the fuel consumption rate can be lowered by increasing the amount of air taken in from the intake system and increasing G / F. On the other hand, since the engine 1 according to the present invention shown in B is operated at the stoichiometric air-fuel ratio, the fuel consumption rate can be lowered by increasing the exhaust gas recirculation amount and increasing G / F. Here, the minimum fuel consumption rate of the conventional engine is the point c, and the minimum fuel consumption rate of the engine 1 according to the present invention is the point b. Therefore, if attention is paid only to the fuel consumption rate, that is, the high efficiency of the engine, since the point c is lower than the point b, it can be said that the conventional engine is superior.

On the other hand, in the conventional engine shown in E of FIG. 3-2, the amount of NO _x in the exhaust gas exhausted to the exhaust system 5 is increased by increasing the amount of air sucked from the intake system 8 and increasing G / F. Can be lowered. On the other hand, since the engine 1 according to the present invention shown in D is operated at the stoichiometric air-fuel ratio, the exhaust gas exhausted to the exhaust system 5 is increased by increasing the recirculation amount of exhaust gas and increasing G / F. it is possible to reduce the amount of NO _x in. This is because the heat capacity of the recirculated exhaust gas is large, so that the combustion temperature of the combustion gas is reduced when the mixture of gasoline and hydrogen and air is combusted in the combustion chamber A to become combustion gas. This is because the amount of NO _x in the exhaust gas can be reduced by reducing the O ₂ concentration in the combustion gas. Here, the amount of NO _x corresponding to the G / F in the lowest fuel consumption rate c of the conventional engine e becomes, _the amount of NO _x corresponding to the G / F in the lowest fuel consumption rate point b of the engine 1 according to the invention d. In other words, if only the engine efficiency is improved, the conventional engine is superior, but if attention is paid to the amount of NO _x in the exhaust gas exhausted to the exhaust system 5, the d point is more than the e point. Therefore, it can be said that the engine 1 according to the present invention is superior. Further, in the conventional engine, in order to increase the efficiency of the engine and reduce the amount of NO _x in the exhaust gas exhausted to the exhaust system 5, the air-fuel ratio of liquid fuel, hydrogen, and air is higher than the stoichiometric air-fuel ratio. It is necessary to operate in the state (λ> 1). Therefore, NO _x contained in the exhaust gas discharged to the exhaust system 5 cannot be purified to such an extent that it can be discharged to the atmosphere by the three-way catalyst. That is, another catalyst, for example, a NO _x storage catalyst or the like is used, or in order to further reduce the amount of NO _x exhausted to the exhaust system 5, the hydrogen addition ratio to gasoline must be increased.

Accordingly, the engine 1 according to the present invention can suppress an increase in the ratio of hydrogen addition to gasoline by recirculating exhaust gas in a large amount, and the amount of NO _x in the exhaust gas discharged to the exhaust system 5 can be suppressed. , i.e. it is possible to reduce the concentration of NO _x in the exhaust gas. Also, a liquid fuel and hydrogen, the extent the air-fuel ratio of the air, since the operation such that the stoichiometric air-fuel ratio, can be discharged to the atmosphere with a low concentration of NO _x discharged into the exhaust system the exhaust gas only at the three-way catalyst The production cost of the internal combustion engine can be reduced without requiring another catalyst such as a NO _x storage catalyst.

  Further, since the amount of air sucked from the intake system 8 is reduced by the exhaust gas recirculated in a large amount, the engine 1 is operated so that the air-fuel ratio of liquid fuel, hydrogen, and air becomes the stoichiometric air-fuel ratio. Therefore, it is necessary to open a throttle valve that adjusts the amount of air taken in from the intake system 8. As a result, the pump loss can be reduced and the efficiency of the engine can be increased as compared with an engine that operates only with liquid fuel.

[Modification 1]
If a large amount of exhaust gas is recirculated to the intake system 8 in a state where there is no remaining hydrogen in the hydrogen tank 31, misfire may occur in the combustion chamber A of each cylinder 6. Therefore, when the amount of remaining hydrogen is exhausted, only liquid fuel is supplied to the engine 1 which is an internal combustion engine, and the exhaust gas recirculation to the intake system 8 of the engine is stopped, so that only the gasoline and air are emptied. The engine 1 is operated so that the fuel ratio becomes the stoichiometric air-fuel ratio.

  Here, another operation method of the engine 1 according to the first embodiment will be described. FIG. 4 is a diagram illustrating another operation flow of the engine according to the first embodiment. The operation method shown in FIG. 4 is simplified because the basic flow is substantially the same as the operation method of the engine 1 according to the first embodiment shown in FIG. First, as shown in FIG. 4, the processing unit 72 of the ECU 7 inputs the engine speed, the accelerator opening, and the air amount (step ST1). Next, the processing unit 72 calculates the gasoline injection amount, the hydrogen addition ratio, the valve opening of the EGR valve 41, the valve opening of the throttle valve 84, and the ignition timing of the spark plug 68 based on the normal addition ratio map. (Step ST2).

  Next, the processing unit 72 inputs the residual hydrogen amount (step ST4). Here, the residual hydrogen amount is calculated based on the tank internal pressure output from the tank internal pressure sensor 35 attached to the hydrogen tank 31. Next, the processing unit 72 determines whether or not there is no remaining hydrogen amount (step ST5). This is to determine whether or not the residual hydrogen amount is zero or substantially zero based on the tank internal pressure. Next, if the remaining hydrogen amount is not exhausted, the processing unit 72 determines the gasoline, hydrogen, air, and air based on the calculated gasoline injection amount, hydrogen addition ratio, EGR valve opening, and throttle valve opening. The engine 1 is operated at the theoretical air fuel ratio (λ = 1) of the air-fuel ratio (step ST3).

  On the other hand, if there is no remaining hydrogen amount, the processing unit 72 sets the hydrogen addition ratio to gasoline to 0, sets the valve opening of the EGR valve to 0, and from the liquid fuel injection means 22 based on the gasoline only map. The injection amount of gasoline to be injected, the valve opening of the throttle valve 84, and the ignition timing of the spark plug 68 are calculated (step ST6). This is because a map of only gasoline, which is a map of the engine speed and the accelerator opening (not shown) stored in the storage unit 73, and an input signal of the engine speed and the accelerator opening input to the ECU 7 as input signals. To be determined. Here, the gasoline-only map used by the processing unit 72 is one of the maps stored in the storage unit 73, and is a map used when the engine 1 is operated only by gasoline that is liquid fuel.

  Next, the processing unit 72 operates the engine 1 with the theoretical air fuel ratio (λ = 1) of the air-fuel ratio between gasoline and air based on the calculated gasoline injection amount, the throttle valve opening, and the ignition timing ( Step ST7). Specifically, the processing unit 72 outputs a liquid fuel injection signal to the liquid combustion injection valve 22 and is calculated at a predetermined injection timing from the liquid fuel injection valve 22 in the intake passage 81 of the intake system 8. Inject an amount of gasoline. Further, the processing unit 72 stops the output of the injection signal when the injection signal is output to the hydrogen injection valve 33 in order to set the addition ratio of hydrogen to gasoline to zero. Further, the processing unit 72 stops the output of the opening / closing signal when the opening / closing signal is output to the EGR valve 41 in order to set the opening degree of the EGR valve 41 to 0. Further, the processing unit 72 outputs a throttle valve opening / closing signal to the throttle valve 84, thereby opening the throttle valve 84 to the calculated valve opening and sucking air into the intake passage 81 of the intake system 8. By opening the intake valve 64 of each cylinder 6, only gasoline and air are taken into the combustion chamber A of each cylinder 6 from the intake system 8. As a result, the combustion chamber A is filled with an air-fuel mixture in which the air-fuel ratio of gasoline and air is the stoichiometric air-fuel ratio (λ = 1). The processing unit 72 then ignites the spark plug 68 by outputting an ignition signal to the spark plug 68. When the spark plug 68 is ignited, the air-fuel mixture in the fuel chamber A is ignited to become combustion gas, and the piston 62 is pushed down to give a rotational force to a crankshaft (not shown) that is rotatably connected via a connecting rod (not shown). .

As described above, when there is no remaining hydrogen in the hydrogen tank 31, only gasoline is supplied to the engine 1 and exhaust gas recirculation to the intake system 8 of the engine 1 is stopped. The risk of misfire occurring in the combustion chamber A of the cylinder 6 can be suppressed. Further, since the engine 1 is operated so that the air-fuel ratio between gasoline and air becomes the stoichiometric air-fuel ratio, even when the remaining hydrogen amount is exhausted, the NO _x contained in the exhaust gas discharged to the exhaust system is ternary. The catalyst can be purified to such an extent that it can be discharged to the atmosphere, and the manufacturing cost of the engine 1 can be reduced.

In the first embodiment, the engine 1 is operated with the hydrogen addition ratio to gasoline being about 20 to 30%. However, even if the hydrogen addition ratio is reduced with respect to the first embodiment, exhaust gas is supplied to the intake system 8. By circulating, NO _x contained in the exhaust gas discharged to the exhaust system 5 can be purified to the extent that it can be discharged to the atmosphere with only the three-way catalyst. Therefore, based on the amount of remaining hydrogen, the ratio of hydrogen addition to gasoline as liquid fuel is changed, that is, halved, so that the air-fuel ratio of gasoline, hydrogen, and air becomes the theoretical air-fuel ratio (λ = 1). To drive. The engine that is the internal combustion engine according to the second embodiment is the same as the engine 1 shown in FIG.

Here, a method of operating the engine 1 according to the second embodiment will be described. FIG. 5 is a diagram illustrating an operation flow of the engine according to the second embodiment. FIG. 6A is a diagram illustrating a relationship between a fuel consumption rate and G / F. FIG. 6B is a diagram illustrating a relationship between the NO _x amount in the exhaust gas discharged to the exhaust system and G / F. The basic operation flow of the engine operating method according to the second embodiment shown in FIG. 5 is the same as the other operating method according to the first embodiment shown in FIG. First, as shown in FIG. 5, the processing unit 72 of the ECU 7 inputs the engine speed, the accelerator opening, and the air amount (step ST1). Next, the processing unit 72 calculates the gasoline injection amount, the hydrogen addition ratio, the valve opening of the EGR valve 41, the valve opening of the throttle valve 84, and the ignition timing of the spark plug 68 based on the normal addition ratio map. (Step ST2).

  Next, the processing unit 72 inputs the residual hydrogen amount (step ST4). Next, the processing unit 72 determines whether or not the residual hydrogen amount is lower than a predetermined amount (step ST8). This is to determine whether or not the residual hydrogen amount is lower than a predetermined amount based on the tank internal pressure. Here, the predetermined amount is, for example, when the exhaust gas is recirculated to the intake system 8 of the engine 1 before hydrogen is newly stored in the hydrogen tank 31, and the intake passage of the intake system 8 from the hydrogen injection valve 33. The amount of hydrogen that can be injected into 81, the amount of 10% of the total amount of hydrogen that can be stored in the hydrogen tank 31, and the like. When the residual hydrogen amount is equal to or greater than the predetermined amount, the processing unit 72 determines whether gasoline, hydrogen, air, and the like are calculated according to the calculated gasoline injection amount, hydrogen addition ratio, EGR valve opening, and throttle valve opening. The engine 1 is operated at the theoretical air fuel ratio (λ = 1) of the air-fuel ratio (step ST3).

  On the other hand, when the remaining hydrogen amount is lower than the predetermined amount, the processing unit 72 determines the gasoline injection amount, the hydrogen addition rate, the valve opening degree of the EGR valve 41, the throttle based on the addition rate half map of the storage unit 72. The valve opening of the valve 84 and the ignition timing of the spark plug 68 are calculated (step ST9). This is because the addition ratio half map which is a map of the engine speed and the accelerator opening (not shown) stored in the storage unit 73 and the input signal of the engine speed and the accelerator opening which are input to the ECU 7 as input signals. To be determined. Here, the addition ratio half map used by the processing unit 72 is one of the maps stored in the storage unit 73, and the hydrogen addition ratio to gasoline is about the normal (about 20 to 30%) addition ratio. It is a map used when the engine 1 is operated with the addition ratio reduced by half (about 10 to 15%). Therefore, in any operating state of the engine 1, the hydrogen addition ratio calculated based on the addition ratio half map becomes a value half that of the hydrogen addition ratio calculated based on the normal addition ratio map. Next, the processing unit 72 determines the gasoline and hydrogen based on the calculated injection amount of gasoline, the hydrogen addition ratio halved from the normal hydrogen addition ratio, the EGR valve opening degree, and the throttle valve opening degree. The engine 1 is operated with the theoretical air fuel ratio (λ = 1) as the air-fuel ratio between the air and air (step ST3).

  As described above, when the amount of remaining hydrogen is lower than the predetermined value, the engine 1 is operated at a hydrogen addition rate that is halved with respect to a normal hydrogen addition rate. Therefore, in the engine 1 which is the internal combustion engine of the second embodiment, even when exhaust gas is recirculated in a large amount as in the first embodiment, stable combustion of gasoline, a mixture of hydrogen and air can be performed.

Further, the relationship between the fuel consumption rate and G / F when the engine 1 according to the second embodiment is operated with the hydrogen addition ratio reduced to half of the normal addition ratio is as shown in F of FIG. Therefore, the minimum fuel consumption rate is f point. Therefore, compared with the point b of the minimum fuel consumption rate when the hydrogen addition ratio is operated at the normal addition ratio as in the engine 1 according to the first embodiment shown in B, the fuel efficiency, that is, the engine efficiency is improved. If attention is paid, it can be said that it is better to operate the engine 1 at a normal addition rate of hydrogen. Further, the relationship between the NO _x amount in the exhaust gas exhausted to the exhaust system 5 and the G / F when the engine 1 according to the second embodiment is operated with the hydrogen addition ratio reduced to half the normal addition ratio. Is as indicated by G in FIG. 6B, and the NO _x amount with respect to G / F at the lowest fuel efficiency rate f is g. Therefore, as compared with the NO _x amount d when the hydrogen addition ratio is operated at the normal addition ratio as in the engine 1 according to the first embodiment shown in D, the NO in the exhaust gas exhausted to the exhaust system 5 is compared. If attention is paid to the amount of _x , it can be said that it is better to operate the engine 1 at a normal hydrogen addition rate.

However, the proportion of hydrogen added to gasoline is different from that of the engine 1 according to the first embodiment in the case of the engine operation method according to the second embodiment, when the residual hydrogen amount is lower than a predetermined value. It becomes half with respect to the addition ratio of. Accordingly, the engine 1 according to the second embodiment can further suppress an increase in the ratio of hydrogen added to gasoline, and the exhaust gas having a low NO _x concentration discharged to the exhaust system can be discharged to the atmosphere with only the three-way catalyst. It can purify and can reduce the manufacturing cost of the internal combustion engine.

In Example 2 described above, when the residual hydrogen amount was lower than the predetermined value, the engine 1 was operated at a hydrogen addition rate halved with respect to the normal hydrogen addition rate, but was discharged into the exhaust system 5. concentration of NO _x in the exhaust gas can be reduced hydrogen ratio if the concentration of the extent that can be discharged to the atmosphere by purification of the only three-way catalyst. Therefore, based on the concentration of NO _x exhaust gas discharged to the exhaust system 5, by changing the adding ratio of hydrogen to gasoline is a liquid fuel, air-fuel ratio is the stoichiometric air-fuel of gasoline and hydrogen and air (lambda = The engine 1 is operated so as to satisfy 1). In addition, since the engine which is an internal combustion engine concerning Example 3 is the same as that of the engine 1 shown in FIG. 1, the description is abbreviate | omitted.

  Here, a method of operating the engine 1 according to the third embodiment will be described. FIG. 7 is a diagram illustrating an operation flow of the engine according to the third embodiment. The operation method of the engine according to the third embodiment shown in FIG. 6 is substantially the same as the operation method according to the second embodiment shown in FIG. First, as shown in FIG. 6, the processing unit 72 of the ECU 7 inputs the engine speed, the accelerator opening, and the air amount (step ST1). Next, the processing unit 72 calculates the gasoline injection amount, the hydrogen addition ratio, the valve opening of the EGR valve 41, the valve opening of the throttle valve 84, and the ignition timing of the spark plug 68 based on the normal addition ratio map. (Step ST2).

  Next, the processing unit 72 inputs the residual hydrogen amount (step ST4). Next, the processing unit 72 determines whether or not the residual hydrogen amount is lower than a predetermined amount (step ST8). This is to determine whether or not the residual hydrogen amount is lower than a predetermined amount based on the tank internal pressure. When the residual hydrogen amount is equal to or greater than the predetermined amount, the processing unit 72 determines whether gasoline, hydrogen, air, and the like are calculated according to the calculated gasoline injection amount, hydrogen addition ratio, EGR valve opening, and throttle valve opening. The engine 1 is operated at the theoretical air fuel ratio (λ = 1) of the air-fuel ratio (step ST3).

  On the other hand, when the remaining hydrogen amount is lower than the predetermined amount, the processing unit 72 determines the gasoline injection amount, the hydrogen addition rate, the valve opening degree of the EGR valve 41 based on each addition rate decrease map in the storage unit 72, The valve opening of the throttle valve 84 and the ignition timing of the spark plug 68 are calculated (step ST10). This is because each addition rate reduction map, which is a map of the engine speed and the accelerator opening (not shown) stored in the storage unit 73, and the input signal of the engine speed and the accelerator opening input to the ECU 7 as input signals. To be determined. Here, each addition rate reduction map used by the processing unit 72 is a plurality of maps stored in the storage unit 73, and the hydrogen addition rate to gasoline is about the normal (about 20 to 30%) addition rate. , For example, a plurality of maps used when the engine 1 is operated with the addition ratio decreased at predetermined intervals. For example, if the normal hydrogen addition rate is 20% and the predetermined interval is 2, the addition rate reduction map is operated with the addition rate of 18%, 16%, 14% ... 4%, 2%, and the engine 1 is operated. It becomes a map used when doing. When the processing unit 72 first determines that the residual hydrogen amount is lower than the predetermined amount, the processing unit 72 uses the addition rate reduction map having the largest hydrogen addition rate reduction amount among the addition rate reduction maps.

  Next, the processing unit 72 determines whether or not the calculated hydrogen addition ratio is equal to or higher than the minimum addition ratio (step ST11). Here, the minimum addition ratio is defined for each addition ratio reduction map, and the combustion chamber of each cylinder 6 with respect to the recirculation amount of the exhaust gas recirculated to the intake system 8 calculated by the processing unit 72. A ratio of hydrogen to gasoline that can perform stable combustion in A. This is because if a large amount of exhaust gas is recirculated to the intake system 8 and the hydrogen addition rate is lower than the minimum addition rate, misfire may occur in the combustion chamber A of each cylinder 6. . If the calculated hydrogen addition ratio is lower than the minimum addition ratio, the process returns to step ST10. When determining that the processing unit 72 has returned to Step 10, the processing unit 72 repeats Step ST9 using an addition rate reduction map in which the hydrogen addition rate reduction amount is one interval less than the most recently used addition rate reduction map.

Next, the processing unit 72 inputs the NO _x concentration of the exhaust gas discharged to the exhaust system 5 (step ST12). Here, the NO _x concentration is output from a NO _x concentration sensor attached to the upstream side of the three-way catalyst 51 in the exhaust passage 52 of the exhaust system 5. Next, the processing unit 72 determines whether or not the NO _x concentration of the exhaust gas is equal to or lower than a specified concentration (step ST13). This is because the concentration of NO _x in the exhaust gas, in order to prevent the exhaust gas can not purify NO _x by only three-way catalyst 51 to an extent that can be discharged into the atmosphere is exhausted to the exhaust system 5. Here, the specified concentration is a concentration that can be purified to such an extent that NO _{x of the} exhaust gas discharged to the exhaust system 5 can be discharged to the atmosphere only by the three-way catalyst 51. That is, step ST13 is that the addition ratio of hydrogen to gasoline is a liquid fuel, the addition ratio of the concentration of NO _x exhaust gas discharged into the exhaust system 5 becomes less concentration of NO _x which can be purified by a three-way catalyst 51 It is.

Then, when the concentration of NO _x in the exhaust gas is the normal concentration or less, the processing unit 72, injection amount of the calculated gasoline, the addition ratio of the hydrogen, the valve opening of the EGR valve, the valve opening of the throttle valve The engine 1 is operated with the theoretical air fuel ratio (λ = 1) of the air / fuel ratio of gasoline, hydrogen, and air (step ST3). On the other hand, when the concentration of NO _x in the exhaust gas is higher than the normal concentration, the processing section 72, than the addition ratio decrease map using the most recent, with the addition ratio decrease map addition ratio decrease of hydrogen 1 interval worth less Returning to step ST10, steps ST10 to ST13 are repeated. In addition, when calculating the addition ratio of hydrogen to gasoline between the addition ratio reduction maps adjacent to each other, the processing unit 72 linearly complements the adjacent addition ratio reduction maps. Alternatively, the ratio of hydrogen to gasoline may be calculated.

By the above, if the residual hydrogen quantity is lower than a predetermined value, decreased hydrogen percentage concentration of NO _x in the exhaust gas discharged into the exhaust system 5 is a concentration of an extent that can be discharged to the atmosphere by purification of the only three-way catalyst Then, the engine 1 is operated. Therefore, in the engine 1 that is the internal combustion engine of the third embodiment, even if the exhaust gas is recirculated in a large amount as in the first embodiment, stable combustion of gasoline, a mixture of hydrogen and air can be performed. In addition, it further suppressed by increasing the proportion of the added hydrogen to gasoline, it can be purified to an extent that can be discharged to the atmosphere with a low concentration of NO _x discharged into the exhaust system the exhaust gas only at the three-way catalyst, an internal combustion engine The manufacturing cost can be reduced.

In the engine 1 according to the second and third embodiments, as in the first modification, when the residual hydrogen amount is exhausted, only the liquid fuel is supplied to the engine 1 that is an internal combustion engine, and the intake air of the engine The engine 1 may be operated so that the exhaust gas recirculation to the system 8 is stopped and the air-fuel ratio of only gasoline and air becomes the stoichiometric air-fuel ratio. Thereby, a possibility that misfire may occur in the combustion chamber A of each cylinder 6 can be suppressed. In addition, even when the amount of residual hydrogen is exhausted, NO _x contained in the exhaust gas exhausted to the exhaust system can be purified to the extent that it can be exhausted to the atmosphere with only a three-way catalyst, and the manufacturing cost of the engine 1 is reduced. can do.

  FIG. 8 is a diagram illustrating a configuration example of an engine (internal combustion engine) according to the fourth embodiment. The engine 1 ′ shown in FIG. 8 is different from the engine 1 shown in FIG. 1 in that the hydrogen supply device 3 includes a passage pressure sensor 36 and a shut-off valve 37. Note that the basic configuration of the engine 1 ′ shown in FIG. 8 is substantially the same as the basic configuration of the engine 1 shown in FIG.

  The hydrogen supply means 3, which is a hydrogen supply means, detects the pressure in the hydrogen supply passage 34 downstream of the hydrogen pump 32, that is, in the hydrogen supply passage 34 on the hydrogen injection valve 33 side. An in-passage pressure sensor that is a means for detecting in-passage pressure is attached. Further, a shutoff valve 37 for shutting off hydrogen supplied from the hydrogen tank 31 serving as a hydrogen reservoir to the hydrogen injection valve 33 is attached to the hydrogen supply passage 34 upstream of the hydrogen pump 32, that is, the hydrogen tank 31 side. . This shut-off valve 37 opens and closes by a servo motor (not shown) and magnetic force, and supplies hydrogen from the hydrogen tank 31 to the hydrogen injection valve 33 via the hydrogen supply passage 34 by a shut-off valve open / close signal from the ECU 7. Is to shut off.

  In the engine 1 ′ that is an internal combustion engine supplied with hydrogen together with gasoline that is liquid fuel, when stopping the operation of the engine 1 ′, turning off the ignition (IG) and stopping the operation of the engine 1 ′, Hydrogen remains in the hydrogen supply passage 34 that connects the hydrogen tank 31 that is the hydrogen storage part of the hydrogen supply device 3 that is the hydrogen supply means to the hydrogen injection valve 33. The remaining hydrogen may leak from the hydrogen supply passage 34 into the vehicle in which the engine 1 ′ is mounted or to the outside of the vehicle over time. This is because hydrogen has the smallest diameter among all atoms and is the substance that leaks most easily.

  Therefore, when the ignition is turned off, that is, when the supply of gasoline and hydrogen as liquid fuel to the engine 1 ′, which is an internal combustion engine, is stopped, the hydrogen flowing out from the hydrogen tank 31 to the hydrogen supply passage 34 is shut off, Until the hydrogen remaining in the supply passage 34 is supplied to the engine 1 ′, the engine 1 ′ needs to be continuously operated. Further, when exhaust gas is recirculated to the intake system 8 of the engine 1 ′, if there is no more hydrogen supplied to the engine 1 ′, misfire occurs in the engine 1 ′, that is, the combustion chamber A of each cylinder 6. There is a risk of doing.

  Therefore, when stopping the supply of gasoline and hydrogen, which are liquid fuels, to the engine 1 ′, which is an internal combustion engine, the shutoff valve 37 is closed to stop the supply of hydrogen, and the intake system of the engine 1 ′, which is an internal combustion engine. When the recirculation of the exhaust gas to 8 is stopped and the pressure in the passage becomes equal to or lower than the specified pressure, the supply of gasoline as liquid fuel is stopped and the operation of the engine 1 'is stopped.

  Here, another operation method of the engine 1 ′ according to the fourth embodiment will be described. FIG. 9 is a diagram illustrating another operation flow of the engine according to the fourth embodiment. The operation method shown in FIG. 9 is simplified because the basic flow is substantially the same as the operation method of the engine 1 according to the first embodiment shown in FIG. First, as shown in FIG. 9, the processing unit 72 of the ECU 7 inputs the engine speed, the accelerator opening, and the air amount (step ST1). Next, the processing unit 72 calculates the gasoline injection amount, the hydrogen addition ratio, the valve opening of the EGR valve 41, the valve opening of the throttle valve 84, and the ignition timing of the spark plug 68 based on the normal addition ratio map. (Step ST2). Next, the processing unit 72 calculates the air-fuel ratio of gasoline, hydrogen, and air based on the calculated air-fuel ratio (λ) based on the calculated gasoline injection amount, hydrogen addition ratio, EGR valve opening, and throttle valve opening. = 1), the engine 1 'is operated (step ST3).

  Next, the processing unit 72 inputs ignition (IG) OFF (step ST14). Next, the processing unit 72 sets the valve opening of the EGR valve to 0 and sets the valve opening of the shut-off valve 37 to 0. (Step ST15). Specifically, the processing unit 72 stops the output of the opening / closing signal when the opening / closing signal is output to the EGR valve 41 in order to set the opening degree of the EGR valve 41 to 0. Thereby, the recirculation of the exhaust gas to the intake system 8 of the engine 1 ′ is stopped. The processing unit 72 stops the output of the opening / closing signal when the opening degree of the cutoff valve 37 is 0, that is, when the opening / closing signal is output to the cutoff valve 37 in order to close the cutoff valve 37. Or when the output signal which opens the shut-off valve 37 is output, the output signal which closes the shut-off valve 37 is output. As a result, the supply of hydrogen from the hydrogen tank 31 to the hydrogen injection valve 33 via the hydrogen supply passage 34 is stopped.

  Next, the gasoline injection amount, the valve opening of the throttle valve 84, and the ignition timing of the spark plug 68 are calculated based on the map of gasoline only at idling (step ST16). This is a map of only the gasoline at idling, which is a map of the engine speed and the accelerator opening (not shown) stored in the storage unit 73, and the engine speed and the accelerator opening that are input to the ECU 7 as input signals. It is determined based on the input signal. Here, the map of only the gasoline at idling used by the processing unit 72 is one of the maps stored in the storage unit 73, and the engine 1 'which is the internal combustion engine uses only gasoline which is liquid fuel at the time of idling. It is a map used when driving 1 '.

  Next, the processing unit 72 performs an idling operation of the engine 1 ′ based on the calculated gasoline injection amount, the throttle valve opening, and the ignition timing (step ST17). At this time, hydrogen in the hydrogen supply passage 34 is injected into the intake passage 81 of the intake system 8 by the hydrogen injection valve 33.

  Next, the processing unit 72 determines whether or not the passage pressure in the hydrogen supply passage 34 is equal to or lower than a specified pressure (step ST18). At this time, the in-passage pressure output from the in-passage pressure sensor 36 already attached to the hydrogen supply passage 34 is input to the processing unit 72. Here, the specified value is used to determine whether the pressure in the hydrogen supply passage 34 is atmospheric pressure or substantially atmospheric pressure. Next, when the pressure in the passage is equal to or lower than the specified pressure, the processing unit 72 stops the operation of the engine 1 ′ that is an internal combustion engine (step ST19). If the passage pressure is higher than the specified pressure, steps ST17 and ST18 are repeated.

  As described above, when the supply of gasoline and hydrogen to the engine 1 ′ is stopped, the shutoff valve 37 is closed to stop the supply of hydrogen, and the recirculation of the exhaust gas is stopped. When it becomes below, supply of gasoline is stopped and operation of engine 1 'is stopped, so that hydrogen does not remain in the hydrogen supply passage, and the risk of hydrogen leaking out from the hydrogen supply passage can be suppressed. Further, since there is no hydrogen supplied to the engine 1 ′, it is possible to suppress the possibility of misfire in the engine 1 ′.

  In the fourth embodiment, the case where the supply of gasoline and hydrogen to the engine 1 ′ is stopped by turning off the ignition (IG) and stopping the engine 1 ′ has been described. However, the present invention is limited to this. It is not a thing. For example, even when the accelerator opening is 0, the supply of gasoline and hydrogen to the engine 1 ′ is stopped. Therefore, the present invention can also be applied to this case. Further, the present invention supplies gasoline and hydrogen, which are liquid fuels, to the engine 1, 1 'when the exhaust gas is recirculated to the intake system 8 of the engine 1, 1', which is an internal combustion engine. However, only hydrogen may be supplied to the engine 1, 1 'when starting the engine 1, 1'.

As described above, the internal combustion engine and the operation method of the internal combustion engine according to the present invention are useful for the internal combustion engine that supplies liquid fuel and hydrogen to the internal combustion engine and the operation method of the internal combustion engine, and in particular, addition of hydrogen to the liquid fuel. It is possible to suppress an increase in the ratio, and it is possible to reduce the NO _x concentration of the exhaust gas discharged to the atmosphere using only the three-way catalyst, and it is suitable for increasing the efficiency of the internal combustion engine.

1 is a diagram illustrating a configuration example of an engine (an internal combustion engine) according to a first embodiment. It is a figure which shows the driving | running flow of the engine concerning Example 1. FIG. It is a figure which shows the relationship between a fuel consumption rate and G / F. Is a diagram showing the relationship between the amount of NO _x and G / F of the exhaust gas exhausted to the exhaust system. It is a figure which shows the other driving | operation flow of the engine concerning Example 1. FIG. It is a figure which shows the driving | running flow of the engine concerning Example 2. FIG. It is a figure which shows the relationship between a fuel consumption rate and G / F. Is a diagram showing the relationship between the amount of NO _x and G / F of the exhaust gas exhausted to the exhaust system. It is a figure which shows the driving | running flow of the engine concerning Example 3. FIG. FIG. 6 is a diagram illustrating a configuration example of an engine (an internal combustion engine) according to a fourth embodiment. It is a figure which shows the driving | running flow of the engine concerning Example 4. FIG.

Explanation of symbols

1, 1 'engine (internal combustion engine)
2 Liquid fuel supply device (liquid fuel supply means)
3 Hydrogen supply device (hydrogen supply means)
4 EGR device (exhaust gas recirculation means)
5 Exhaust system 51 Three-way catalyst 6 Each cylinder 7 ECU
8 Intake system

Claims (7)

Liquid fuel supply means for supplying liquid fuel in the liquid fuel tank to the internal combustion engine;
Hydrogen supply means for supplying hydrogen stored in the hydrogen storage part to the internal combustion engine;
Exhaust gas recirculation means for recirculating exhaust gas discharged to the exhaust system of the internal combustion engine to the intake system of the internal combustion engine;
A three-way catalyst for purifying the exhaust gas of the exhaust system;
An internal combustion engine comprising:
When the exhaust gas is recirculated to the intake system of the internal combustion engine, the liquid fuel and hydrogen are supplied to the internal combustion engine, and the liquid fuel and hydrogen and the air taken in from the intake system are emptied. An internal combustion engine that is operated so that a fuel ratio becomes a stoichiometric air-fuel ratio. The internal combustion engine further comprises a concentration of NO _x detection means for detecting the concentration of NO _x in the exhaust gas to the exhaust system,
2. The internal combustion engine according to claim 1, wherein an addition ratio of the hydrogen to the liquid fuel supplied to the internal combustion engine is changed based on the NO _x concentration. 3. The internal combustion engine according to claim 2, wherein the addition ratio of the hydrogen to the liquid fuel is an addition ratio at which the NO _x concentration of the exhaust gas is equal to or less than the NO _x concentration that can be purified by the three-way catalyst. The hydrogen supply means further comprises a residual hydrogen amount detection means for detecting a residual hydrogen amount in the hydrogen reservoir,
The internal combustion engine according to any one of claims 1 to 3, wherein an addition ratio of the hydrogen to the liquid fuel is changed based on the residual hydrogen amount.   When the residual hydrogen amount is exhausted, only the liquid fuel is supplied to the internal combustion engine, and the recirculation of exhaust gas to the intake system of the internal combustion engine is stopped, and the liquid fuel and the air are emptied. The internal combustion engine according to claim 4, wherein the engine is operated such that the fuel ratio becomes a stoichiometric air-fuel ratio. The hydrogen supply means includes a passage pressure detection means for detecting a passage pressure of the hydrogen supply passage to a hydrogen supply passage connecting the hydrogen reservoir to a hydrogen injection valve for supplying hydrogen to the internal combustion engine,
A shut-off valve that shuts off hydrogen supplied from the hydrogen reservoir to the hydrogen injection valve;
Further comprising
When stopping the supply of the liquid fuel and the hydrogen to the internal combustion engine,
Closes the shut-off valve and stops the supply of hydrogen, and stops the recirculation of exhaust gas to the intake system of the internal combustion engine,
The internal combustion engine according to claim 1, wherein the supply of the liquid fuel is stopped when the pressure in the passage becomes equal to or lower than a specified pressure. Supply at least one of liquid fuel or hydrogen to the internal combustion engine, recirculate the exhaust gas of the exhaust system of the internal combustion engine to the intake system of the internal combustion engine, and purify the exhaust gas of the exhaust system by a three-way catalyst An internal combustion engine operating method
When the exhaust gas is recirculated to the intake system of the internal combustion engine, the liquid fuel and hydrogen are supplied to the internal combustion engine, and the liquid fuel and hydrogen and the air taken in from the intake system are emptied. An operation method of an internal combustion engine, wherein the operation is performed so that the fuel ratio becomes a stoichiometric air-fuel ratio.

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