Internal combustion engine

Abstract

To provide an internal combustion engine capable of suppressing generation of back fire.SOLUTION: A first injection valve injects ammonia into an intake path. A second injection valve injects hydrogen into the intake path. A control device causes the first injection valve to inject the ammonia in a first injection period and the second injection valve to inject the hydrogen in a second injection period. At least a part of the second injection period overlaps with the first injection period. A second start time at which the second injection period begins is after the first start time at which the first injection period begins, and / or a second end time at which the second injection period ends is before the first end time at which the first injection period ends.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an internal combustion engine. [Background technology]

[0002] As a conventional invention related to an internal combustion engine, for example, an engine system described in Patent Document 1 is known. In this engine system, an injector injects ammonia gas and hydrogen gas into an intake pipe. Then, the ammonia gas and hydrogen gas are combusted in a combustion chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-097421 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, hydrogen has the property of being very easily ignited, so in the engine system described in Patent Document 1, backfires may occur in which hydrogen gas ignites in the intake pipe.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an internal combustion engine capable of suppressing the occurrence of backfire. [Means for solving the problem]

[0006] The first aspect is An internal combustion engine having a combustion chamber and an intake passage connected to the combustion chamber, The internal combustion engine includes a first injector, a second injector, and a control device, The first injection valve injects ammonia into the intake path, The second injection valve injects hydrogen into the intake path, the control device causes the first injector to inject the ammonia during a first injection period and causes the second injector to inject the hydrogen during a second injection period; At least a portion of the second ejection period overlaps with the first ejection period; a second start time at which the second injection period starts is later than a first start time at which the first injection period starts, and / or a second end time at which the second injection period ends is earlier than a first end time at which the first injection period ends. It is an internal combustion engine.

[0007] The second aspect is, The injection port of the second injection valve is located within a first injection region in which fuel is injected by the first injection valve. The internal combustion engine according to the first aspect.

[0008] The third aspect is, A second injection region where fuel is injected by the second injection valve is located within a first injection region where fuel is injected by the first injection valve. The internal combustion engine according to either the first or second aspect. Effect of the Invention

[0009] According to the present invention, the occurrence of backfire can be suppressed. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of an internal combustion engine 10 . [Diagram 2] FIG. 2 is an enlarged view of the intake path R1. [Diagram 3] FIG. 3 is a timing chart showing the operation of the internal combustion engine 10. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Embodiment) [Structure of an internal combustion engine] Hereinafter, the structure of an internal combustion engine 10 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of the internal combustion engine 10. FIG. 2 is an enlarged view of the intake path R1. In FIG. 1 and FIG. 2, the directions in which the piston 18 moves are defined as the upward direction and the downward direction. However, the upward direction and the downward direction in this specification are directions defined for the convenience of explanation, and may not coincide with the upward direction and the downward direction when the internal combustion engine 10 is actually used.

[0012] The internal combustion engine 10 is used, for example, as a power source for an automobile. The internal combustion engine 10 is a four-stroke engine that uses ammonia as fuel. In the internal combustion engine 10, hydrogen is used as a combustion aid for the ammonia. Although the internal combustion engine 10 in FIG. 1 is an engine having one cylinder, an engine having multiple cylinders is generally used. When the internal combustion engine 10 is an engine having multiple cylinders, the multiple cylinders are arranged in one row, two rows, or four rows. The internal combustion engine 10 includes an engine body 12, a crankshaft 14, a connecting rod 16, a piston 18, an intake valve 20, an exhaust valve 22, an ignition plug 24, and an ignition coil 26.

[0013] The engine body 12 includes a cylinder block 12a, a cylinder head 12b, and a crankcase 12c. The cylinder block 12a is provided with a cylinder Sy. The cylinder Sy has a cylindrical shape with a central axis extending along the vertical axis.

[0014] The cylinder head 12b is located on the cylinder block 12a. The cylinder head 12b is fixed to the cylinder block 12a. The cylinder head 12b is provided with a combustion chamber Sp. The combustion chamber Sp is located above the cylinder Sy. The combustion chamber Sp is connected to the cylinder Sy.

[0015] The cylinder head 12b is provided with an intake port P1 and an exhaust port P2. The intake port P1 and the exhaust port P2 are connected to the combustion chamber Sp. The intake port P1 is a part of the intake path R1. The intake path R1 is a path through which air or a mixture of fuel and air passes. The exhaust port P2 is a part of the exhaust path R2. The exhaust path R2 is a path through which exhaust gas passes. In this way, the internal combustion engine 10 is provided with the combustion chamber Sp, the intake path R1 connected to the combustion chamber Sp, and the exhaust path R2.

[0016] The crankcase 12c is located below the cylinder block 12a. The crankcase 12c is fixed to the cylinder block 12a. The engine body 12 as described above is made of cast iron.

[0017] The crankshaft 14 is supported by the cylinder block 12a and the crankcase 12c and can rotate about a rotation axis that is perpendicular to the vertical axis.

[0018] The piston 18 is located in the cylinder Sy. The piston 18 has a cylindrical shape. The piston 18 can move upward and downward.

[0019] The connecting rod 16 connects the crankshaft 14 and the piston 18. As a result, when the crankshaft 14 rotates, the piston 18 moves up and down. The combustion chamber Sp described above is a space surrounded by the piston 18 and the cylinder head 12b when the piston 18 is located at top dead center (TDC).

[0020] The intake valve 20 is supported by the cylinder head 12b. The intake valve 20 is located downstream of a first injector 29 and a second injector 30, which will be described later, in the intake path R1. The intake valve 20 opens and closes the intake path R1. When the intake valve 20 opens the intake path R1, a mixture of fuel and air flows from the intake path R1 into the combustion chamber Sp. The exhaust valve 22 is supported by the cylinder head 12b. The exhaust valve 22 opens and closes the exhaust path R2. When the exhaust valve 22 opens the exhaust path R2, exhaust flows from the Sp to the exhaust path R2. The intake valve 20 and the exhaust valve 22 as described above are driven by a valve mechanism (not shown).

[0021] The spark plug 24 is fixed to the cylinder head 12b. The spark plug 24 includes a center electrode and a ground electrode. The center electrode and the ground electrode are exposed to the combustion chamber Sp.

[0022] The ignition coil 26 applies a high voltage between the center electrode and the ground electrode of the spark plug 24 based on an ignition signal from the control device 100, which will be described later. This generates a spark between the center electrode and the ground electrode of the spark plug 24, igniting the fuel in the combustion chamber Sp.

[0023] The internal combustion engine 10 further includes an intake manifold 27, an exhaust manifold 28, a first injector 29, a second injector 30, a throttle valve 32, a throttle position sensor 34, an air flow meter 36, a water temperature sensor 38, and a crank angle sensor 40.

[0024] The intake manifold 27 is connected to the cylinder head 12b. The intake manifold 27 is a part of the intake path R1. The exhaust manifold 28 is connected to the cylinder head 12b. The exhaust manifold 28 is a part of the exhaust path R2.

[0025] The first injector 29 injects ammonia into the intake path R1. Specifically, as shown in FIG. 2, the first injector 29 has an injection port 29a. The first injector 29 injects ammonia from the injection port 29a. The first injector 29 is fixed to the cylinder head 12b. The first injector 29 is located above a center line C0 of the intake path R1. Here, the direction in which air flows in the intake path R1 is called the intake direction. The center line C0 is a line obtained by connecting the centers of gravity of a figure formed by the intake path R1 in a cross section perpendicular to the intake direction.

[0026] The first injection valve 29 has a first injection angle θ1. The first injection angle θ1 will be described below. As shown in FIG. 2, the first injection valve 29 has a cone-shaped first injection area A1. The first injection area A1 has a first center line C1. The first center line C1 extends from the first injection valve 29 toward the downstream of the intake path R1. That is, the first injection valve 29 injects fuel toward the downstream of the intake path R1. When viewed in a direction perpendicular to the first center line C1, an acute angle formed at the apex of the first injection area A1 is defined as the first injection angle θ1. Note that the first injection area A1, the first injection angle θ1, and the first center line C1 are parameters measured in a state where no air flow is generated in the intake path R1.

[0027] The second injector 30 injects hydrogen into the intake path R1. Specifically, as shown in FIG. 2, the second injector 30 has an injection port 30a. The second injector 30 injects hydrogen from the injection port 30a. The second injector 30 is fixed to the cylinder head 12b. The second injector 30 is located below the center line C0 of the intake path R1. The second injector 30 is located downstream of the first injector 29 in the intake path R1.

[0028] 2, the second injection valve 30 has a second injection angle θ2. Also, the second injection valve 30 has a cone-shaped second injection area A2. The definitions of the second injection angle θ2, the second injection area A2, and the second center line C2 are the same as those of the first injection angle θ1, the first injection area A1, and the first center line C1, respectively, and therefore will not be described.

[0029] Moreover, the second injection area A2 into which the fuel is injected by the second injector 30 is located within the first injection area A1 into which the fuel is injected by the first injector 29. That is, the second injection area A2 does not protrude from the first injection area A1. Therefore, the second injection area A2 is surrounded by the first injection area A1. To satisfy this condition, the first injector 29 and the second injector 30 satisfy the conditions described below. The injection port 30a of the second injector 30 is located within the first injection area A1 into which the fuel is injected by the first injector 29. Furthermore, the volume of the second injection area A2 is smaller than the volume of the first injection area A1. Furthermore, the second injection angle θ2 of the second injector 30 is smaller than the first injection angle θ1 of the first injector 29. Furthermore, the length L2 of the second injection area A2 in the direction in which the second center line C2 extends is shorter than the length L1 of the first injection area A1 in the direction in which the first center line C1 extends. The length L1 depends on the length of the first injection period T1 during which the first injector 29 injects fuel. As the first injection period T1 becomes longer, the length L1 becomes longer. Similarly, the length L2 depends on the length of the second injection period T2 during which the second injector 30 injects fuel. As the second injection period T2 becomes longer, the length L2 becomes longer. Thus, the second injection period T2 is shorter than the first injection period T1.

[0030] Furthermore, if the second injection period T2 is shorter than the first injection period T1, the volume of hydrogen injected during the second injection period T2 is smaller than the volume of ammonia injected during the first injection period T1. In this embodiment, the volume of hydrogen is 30% or less of the volume of ammonia.

[0031] When the internal combustion engine 10 has a plurality of cylinders, the first injector 29 and the second injector 30 are provided for each cylinder.

[0032] As shown in Fig. 1, the throttle valve 32 is located upstream of the first injector 29 and the second injector 30 in the intake path R1. The throttle valve 32 opens and closes the intake path R1 in response to the driver's operation of the accelerator pedal. In this way, the throttle valve 32 adjusts the amount of air supplied to the combustion chamber Sp. The throttle position sensor 34 detects the open / closed state of the throttle valve 32.

[0033] The air flow meter 36 is located in the intake path R1 upstream of the throttle valve 32. The air flow meter 36 detects the amount of air passing through the intake path R1.

[0034] The water temperature sensor 38 is provided in the engine body 12. The water temperature sensor 38 detects the water temperature of the engine body 12. The water temperature is the temperature of the cooling water for the engine body 12.

[0035] The crank angle sensor 40 is provided in the engine body 12. The crank angle sensor 40 detects the rotation angle of the crankshaft 14.

[0036] The internal combustion engine 10 further includes a control device 100. The control device 100 is an ECU (Engine Control Unit). The control device 100 controls the operation of the internal combustion engine 10 based on signals from a throttle position sensor 34, an air flow meter 36, a water temperature sensor 38, and a crank angle sensor 40. Specifically, the control device 100 controls the timing of fuel injection by the first injector 29 and the second injector 30, and the timing of ignition by the spark plug 24.

[0037] [Operation of the internal combustion engine 10] Next, the operation of the internal combustion engine 10 will be described with reference to the drawings.

[0038] As shown in Fig. 3, the control device 100 causes the first injector 29 to inject ammonia in a first injection period T1. The first injection period T1 is a period spanning an exhaust stroke and an intake stroke. Therefore, a first start time s1 at which the first injection period T1 starts is before a time tt at which the piston 18 is located at the top dead center. Also, a first end time e1 at which the first injection period T1 ends is before a time tb at which the piston 18 is located at the bottom dead center.

[0039] The control device 100 causes the second injection valve 30 to inject hydrogen during the second injection period T2. At least a portion of the second injection period T2 overlaps with the first injection period T1. In this embodiment, the entire second injection period T2 overlaps with the first injection period T1. Therefore, the second start time s2 at which the second injection period T2 starts is after the first start time s1 at which the first injection period T1 starts. Furthermore, the second end time e2 at which the second injection period T2 ends is before the first end time e1 at which the first injection period T1 ends. Therefore, the second injection period T2 is shorter than the first injection period T1. Furthermore, in this embodiment, the second injection period T2 overlaps with the time c1 in the middle of the first injection period T1.

[0040] [effect] According to the internal combustion engine 10, the occurrence of backfire can be suppressed. More specifically, at least a part of the second injection period T2 during which the second injector 30 injects hydrogen into the intake path R1 overlaps with the first injection period T1 during which the first injector 29 injects ammonia into the intake path R1. The second start time s2 at which the second injection period T2 starts is after the first start time s1 at which the first injection period T1 starts. Furthermore, the second end time e2 at which the second injection period T2 ends is before the first end time e1 at which the first injection period T1 ends. As a result, there is no period during which only hydrogen is injected into the intake path R1. That is, hydrogen is easily injected into the ammonia. Therefore, hydrogen is mixed with the ammonia, which has a property of being difficult to ignite. Therefore, hydrogen is suppressed from igniting in the intake path R1, and the occurrence of backfire is suppressed.

[0041] As a method for suppressing backfire, for example, there is an internal combustion engine that employs a direct injection fuel supply method in which a second injection valve injects hydrogen into a combustion chamber. However, in the case of a direct injection fuel supply method, the second injection valve needs to inject hydrogen at higher pressure. Also, a part of the second injection valve faces the combustion chamber. Since the combustion chamber is in a high temperature and high pressure state, the second injection valve is required to have a high sealing performance. As a result, the manufacturing cost of an internal combustion engine that employs a direct injection fuel supply method is high.

[0042] On the other hand, in the internal combustion engine 10, the second injection valve 30 injects hydrogen into the intake path R1, so the pressure at which the second injection valve 30 injects hydrogen may be low. Also, since the intake path R1 is unlikely to be in a high temperature or high pressure state, the second injection valve 30 is not required to have high sealing properties. As a result, the manufacturing costs of the internal combustion engine 10 are reduced.

[0043] Furthermore, in the case of a direct injection fuel supply method, as described above, the second injector needs to inject hydrogen at higher pressure. When the amount of hydrogen remaining in the tank decreases, the pressure of the hydrogen in the tank decreases. In this case, the second injector cannot inject hydrogen with sufficient pressure. Therefore, all of the hydrogen in the tank cannot be used up. As a result, a vehicle equipped with an internal combustion engine to which a direct injection fuel supply method is applied has a shorter driving distance.

[0044] On the other hand, in the internal combustion engine 10, the second injection valve 30 injects hydrogen into the intake path R1, so the pressure at which the second injection valve 30 injects hydrogen may be low. Therefore, the internal combustion engine 10 can use a large amount of hydrogen in the tank. As a result, a vehicle equipped with the internal combustion engine 10 can travel a longer distance.

[0045] In the internal combustion engine 10, the injection port 30a of the second injection valve 30 is located in the first injection region A1 where the first injection valve 29 injects fuel. As a result, hydrogen is injected into the ammonia. Therefore, hydrogen is more mixed with the ammonia, which has a property of being difficult to ignite. Therefore, hydrogen is more prevented from igniting in the intake path R1, and the occurrence of backfire is more suppressed.

[0046] In the internal combustion engine 10, the second injection region A2 into which fuel is injected by the second injection valve 30 is located within the first injection region A1 into which fuel is injected by the first injection valve 29. As a result, hydrogen is injected into the ammonia. Therefore, hydrogen is further mixed with the ammonia, which has a property of being difficult to ignite. Therefore, hydrogen is further prevented from igniting in the intake path R1, and the occurrence of backfire is further suppressed.

[0047] In the internal combustion engine 10, the second injector 30 is located downstream of the first injector 29 in the intake passage R1. This makes it easier for the second injector 30 to inject hydrogen into the mixture containing ammonia. Therefore, hydrogen is more likely to be mixed with ammonia, which has a property of being difficult to ignite. This further suppresses hydrogen from igniting in the intake passage R1, and further suppresses the occurrence of backfire.

[0048] In the internal combustion engine 10, the second injection period T2 is shorter than the first injection period T1. This reduces the amount of hydrogen injected. This further reduces the concentration of hydrogen in the intake path R1. This further reduces the ignition of hydrogen in the intake pipe, thereby further reducing the occurrence of backfire.

[0049] Hydrogen is lighter than ammonia. Therefore, hydrogen moves upward in the intake path R1. Therefore, the first injector 29 injects ammonia and is located above the center line C0 of the intake path R1. The second injector 30 injects hydrogen and is located below the center line C0 of the intake path R1. As a result, hydrogen moving up in the intake path R1 is mixed with ammonia injected from above the center line C0. Therefore, hydrogen is mixed more with ammonia, which has a property of being difficult to ignite. Therefore, hydrogen is more suppressed from igniting in the intake path R1, and the occurrence of backfire is more suppressed.

[0050] In the internal combustion engine 10, the second injection period T2 overlaps with the time c1 in the middle of the first injection period T1. This makes it easier for hydrogen to be injected into the ammonia. Therefore, hydrogen is more likely to be mixed with the ammonia, which has a property of being difficult to ignite. This further suppresses hydrogen from igniting in the intake path R1, and further suppresses the occurrence of backfire.

[0051] (Other embodiments) The internal combustion engine according to the present invention is not limited to the internal combustion engine 10, and can be modified within the scope of the invention.

[0052] It should be noted that at least a part of the second injection period T2 may overlap with the first injection period T1. Therefore, it is sufficient that either the second start time s2 at which the second injection period T2 starts is later than the first start time s1 at which the first injection period T1 starts, or the second end time e2 at which the second injection period T2 ends is earlier than the first end time e1 at which the first injection period T1 ends. Therefore, the second start time s2 may be earlier than the first start time s1, and the second end time e2 may be earlier than the first end time e1. Also, the second start time s2 may be later than the first start time s1, and the second end time e2 may be later than the first end time e1. This shortens the period during which only hydrogen is injected into the intake path R1. That is, hydrogen is more likely to be injected into the ammonia. Therefore, hydrogen is mixed with ammonia, which has a property of being difficult to ignite. Therefore, hydrogen is suppressed from igniting in the intake path R1, and the occurrence of a backfire is suppressed.

[0053] The first injector 29 and the second injector 30 are fixed to the cylinder head 12b. However, the first injector 29 and the second injector 30 may be fixed to the intake manifold 27.

[0054] The second injection angle θ2 of the second injector 30 may be equal to or smaller than the first injection angle θ1 of the first injector 29.

[0055] The automobile may be a four-wheeled automobile, a three-wheeled automobile, or a two-wheeled automobile. A two-wheeled automobile is a leaning vehicle in which the body leans in the same direction as the direction of travel around the corner. A three-wheeled automobile may be a leaning vehicle, or may be a vehicle that rolls in the opposite direction to the direction of travel around the corner.

[0056] The internal combustion engine 10 may be used as a power source for vehicles other than automobiles. Also, the internal combustion engine 10 may be used as a generator for generating electric power for an EV (Electric Vehicle).

[0057] When the internal combustion engine 10 has a plurality of cylinders, one first injector 29 may supply ammonia and one second injector 30 may supply hydrogen to the plurality of cylinders.

[0058] The injection port 30a of the second injection valve 30 does not necessarily have to be located within the first injection region A1 in which the first injection valve 29 injects fuel.

[0059] The second injection region A2 into which the fuel is injected by the second injection valve 30 does not necessarily have to be located within the first injection region A1 into which the fuel is injected by the first injection valve 29.

[0060] The second injector 30 does not necessarily have to be located downstream of the first injector 29 in the intake path R1.

[0061] The second injection period T2 does not have to be shorter than the first injection period T1. [Explanation of symbols]

[0062] 10: Internal combustion engine 12: Main body of the engine 12a: Cylinder block 12b: Cylinder head 12c: Crankcase 14: Crankshaft 16: Connecting rod 18: Piston 20: Intake valve 22: Exhaust valve 24: Spark plug 26: Ignition coil 27: Intake manifold 28: Exhaust manifold 29: First injector 29a: Nozzle 30: Second injector 30a: Nozzle 32: Throttle valve 100: Control device A1: 1st injection area A2:Second injection area C0: Center line C1: 1st center line C2: 2nd center line P1: Intake port P2: Exhaust port R1: Intake path R2: Exhaust route Sp: Combustion chamber Sy: Cylinder T1: First injection period T2: Second injection period e1: First end time e2: Second end time s1: 1st start time s2: 2nd start time

Claims

1. An internal combustion engine having a combustion chamber and an intake passage connected to the combustion chamber, The internal combustion engine includes a first injector, a second injector, and a control device. The first injection valve injects ammonia into the intake path, The second injection valve injects hydrogen into the intake path, the control device causes the first injector to inject the ammonia during a first injection period and causes the second injector to inject the hydrogen during a second injection period; At least a portion of the second ejection period overlaps with the first ejection period; a second start time at which the second injection period starts is later than a first start time at which the first injection period starts, and / or a second end time at which the second injection period ends is earlier than a first end time at which the first injection period ends. Internal combustion engine.

2. An injection port of the second injection valve is located within a first injection region in which fuel is injected by the first injection valve.

2. The internal combustion engine of claim 1.

3. a second injection region into which fuel is injected by the second injection valve is located within a first injection region into which fuel is injected by the first injection valve; 3. An internal combustion engine according to claim 1 or 2.

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