Internal combustion engine

Abstract

To stabilize combustion in an internal combustion engine in which a plurality of different fuels can be used simultaneously.SOLUTION: The present invention resides in an internal combustion engine in which a plurality of different fuels can be used simultaneously, and which has a plurality of injection valves (first injection valve 41a, second injection valve 41b) that each inject different fuels so that the different fuels flow into a single combustion chamber 19, and of the fuels injected from the plurality of injection valves (first injection valve 41a, second injection valve 41b), the fuel with the greatest ignition energy flows into the combustion chamber 19 first. By allowing the fuel with the greater ignition energy to flow into the combustion chamber 19 first, premature ignition of the fuel with the less ignition energy in the combustion chamber 19 is alleviated, thereby making it possible to prevent combustion from becoming unstable.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Conventionally, an internal combustion engine capable of simultaneously using two different types of fuel has been widely known. Patent Document 1 discloses an internal combustion engine that simultaneously supplies two types of fuel, a first fuel that is hydrogen and a second fuel that is a liquid fuel, to one combustion chamber. In this internal combustion engine, when the two types of fuel are simultaneously supplied to one combustion chamber, the improvement of exhaust gas is achieved while maintaining the cruising range by changing the ratio of the amounts of the two types of fuel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, it is generally known that hydrogen fuel has a very small ignition energy compared to gasoline, which is a liquid fuel. The fact that the ignition energy is small means that it is likely to self-ignite using a heat source such as an ignition plug or an exhaust valve. Therefore, when hydrogen fuel flows into the combustion chamber simultaneously with other fuel, if the hydrogen fuel self-ignites, the heat energy of the hydrogen fuel may cause the other fuel to also ignite, resulting in unstable combustion instead of combustion at an appropriate timing.

[0005] The present invention has been made in view of the above-described problems, and an object thereof is to stabilize combustion in an internal combustion engine capable of simultaneously using a plurality of different fuels.

Means for Solving the Problems

[0006] The present invention relates to an internal combustion engine capable of simultaneously using a plurality of different fuels, and has a plurality of injection valves that inject different fuels so as to cause the different fuels to flow into one combustion chamber. Among the fuels injected from the plurality of injection valves, the fuel with a large ignition energy is caused to flow into the combustion chamber.

Effect of the Invention

[0007] According to the present invention, in an internal combustion engine capable of simultaneously using a plurality of different fuels, combustion can be stabilized.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0009] An embodiment according to the present invention is an internal combustion engine capable of simultaneously using a plurality of different fuels, and has a plurality of injection valves (a first injection valve 41a and a second injection valve 41b) that inject different fuels so as to cause the different fuels to flow into one combustion chamber 19. Among the fuels injected from the plurality of injection valves (the first injection valve 41a and the second injection valve 41b), the fuel with a large ignition energy is caused to flow into the combustion chamber 19. By causing the fuel with a large ignition energy to flow into the combustion chamber 19, it is possible to suppress the combustion from becoming unstable because the premature ignition of the fuel with a small ignition energy in the combustion chamber 19 is alleviated.

Examples

[0010] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described. FIG. 1 is a diagram showing a schematic configuration of a vehicle 10 equipped with an internal combustion engine according to this embodiment. Note that FIG. 1 is simplified for the sake of explanation to describe this embodiment, and it is assumed that the vehicle has components that are not shown but are normally provided.

[0011] The vehicle 10 of this embodiment is equipped with an engine 11 as an internal combustion engine. The engine 11 includes an engine body 12, an intake system for taking in intake air for combustion of the engine body 12, an exhaust system for discharging exhaust gas from the engine body 12 to the outside, a fuel system for supplying a plurality of different fuels to the engine body 12, a control system for controlling the engine body 12 and related devices, and the like.

[0012] The engine body 12 performs a series of strokes including an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. Note that the engine body 12 will be described as a single-cylinder engine for ease of understanding, but it may also be a multi-cylinder engine.

[0013] The engine body 12 is configured by integrally coupling a cylinder block 13 and a cylinder head 14. The cylinder block 13 has a crank chamber 15 formed inside. A crankshaft 16 is rotatably supported in the crank chamber 15. A piston 17 is fitted in the cylinder block 13, and as the piston 17 reciprocates along the cylinder axis Cy, the crankshaft 16 rotates about the crank axis Cr via a connecting rod 18. A combustion chamber 19 is formed between the cylinder block 13 and the cylinder head 14. A spark plug 20 is disposed on the cylinder head 14 so that its tip is located inside the combustion chamber 19.

[0014] In addition, a crank angle sensor 61 for detecting the crank angle (rotation angle of the crankshaft 16) is disposed in the engine body 12. The crank angle sensor 61 transmits the detected crank angle information to the control device 60. The control device 60 controls the ignition timing of the spark plug 20 based on the crank angle information detected by the crank angle sensor 61.

[0015] In addition, an intake port portion 21 and an exhaust port portion 31 that communicate with the combustion chamber 19 are formed in the cylinder head 14. The intake port portion 21 extends obliquely from the combustion chamber 19 toward one side wall surface of the cylinder head 14. The intake port portion 21 guides the intake air taken in via the intake system to the combustion chamber 19. Further, the exhaust port portion 31 extends obliquely from the combustion chamber 19 toward the other side wall surface of the cylinder head 14. The exhaust port portion 31 guides the exhaust gas burned in the combustion chamber 19 to the exhaust system.

[0016] FIG. 2 is a view of the cylinder head 14 seen along the cylinder axis Cy. The intake port portion 21 of the present embodiment has a plurality of intake ports (first intake port 22a, second intake port 22b). The first intake port 22a and the second intake port 22b extend substantially parallel to each other. Specifically, the first intake port 22a and the second intake port 22b are separated in the crankshaft Cr direction of the crankshaft 16. The first intake port 22a and the second intake port 22b of the present embodiment communicate with one combustion chamber 19.

[0017] On the other hand, the exhaust port portion 31 of the present embodiment has a plurality of exhaust ports (first exhaust port 32a, second exhaust port 32b). The first exhaust port 32a and the second exhaust port 32b extend substantially parallel to each other. Specifically, the first exhaust port 32a and the second exhaust port 32b are separated in the crankshaft Cr direction of the crankshaft 16. The first exhaust port 32a and the second exhaust port 32b of the present embodiment communicate with one combustion chamber 19.

[0018] In addition, an intake valve portion 23 for taking in intake air from the intake port portion 21 into the combustion chamber 19 by opening a valve is disposed in the intake port portion 21. Further, an exhaust valve portion 33 for discharging exhaust gas from the combustion chamber 19 to the exhaust port portion 31 by opening a valve is disposed in the exhaust port portion 31.

[0019] The intake valve portion 23 of the present embodiment has a plurality of intake valves (a first intake valve 24a and a second intake valve 24b). The first intake valve 24a corresponds to the first intake port 22a, and the second intake valve 24b corresponds to the second intake port 22b. On the other hand, the exhaust valve portion 33 of the present embodiment has a plurality of exhaust valves (a first exhaust valve 34a and a second exhaust valve 34b). The first exhaust valve 34a corresponds to the first exhaust port 32a, and the second exhaust valve 34b corresponds to the second exhaust port 32b.

[0020] Returning to FIG. 1, the engine 11 has, as an intake system, an intake passage 25, an air cleaner 26, a throttle valve 27, and the like. The intake passage 25 is a passage that guides intake air taken in from the outside of the vehicle 10 to the combustion chamber 19 via the intake port portion 21. The intake passage 25 is constituted by, for example, an intake pipe. When the engine body 12 is a multi-cylinder engine, the downstream side of the intake passage 25 is constituted by an intake manifold. An air cleaner 26 and a throttle valve 27 are arranged in the intake passage 25 in order from the upstream side.

[0021] The air cleaner 26 purifies the intake air by removing foreign matters such as dust and dirt contained in the intake air. The throttle valve 27 adjusts the flow rate of the intake air by opening and closing. The throttle valve 27 adjusts the flow rate of the intake air based on control by the control device 60. Note that an air flow sensor 28 and a throttle opening sensor 29 are arranged in the intake passage 25 (the periphery of the intake passage 25). The air flow sensor 28 measures information on the intake air volume and transmits the measured information on the intake air volume to the control device 60. The throttle opening sensor 29 detects information on the opening degree of the throttle valve 27 and transmits the detected information on the opening degree of the throttle valve to the control device 60.

[0022] In addition, the engine 11 has an exhaust passage 35, a catalytic converter 36, etc. as an exhaust system. The exhaust passage 35 is a passage for exhausting the exhaust gas burned in the combustion chamber 19 to the outside of the vehicle 10 via the exhaust port portion 31. The exhaust passage 35 is constituted by, for example, an exhaust pipe. When the engine body 12 is a multi-cylinder engine, the upstream side of the exhaust passage 35 is constituted by an exhaust manifold. A catalytic converter 36 is disposed in the exhaust passage 35. The catalytic converter 36 purifies the exhaust gas by oxidizing and reducing the harmful components contained therein.

[0023] In addition, the engine 11 has an injection valve portion 40 as a fuel system. As shown in FIG. 2, the injection valve portion 40 of the present embodiment has a plurality of injection valves (the first injection valve 41a and the second injection valve 41b). The injection valve portion 40 of the present embodiment injects fuel so that different fuels flow into one combustion chamber 19. That is, the engine 11 of the present embodiment can use a plurality of different fuels simultaneously. Specifically, in the present embodiment, the first injection valve 41a injects hydrogen fuel, which is a gaseous fuel, as the first fuel, and the second injection valve 41b injects gasoline fuel, which is a liquid fuel, as the second fuel. Here, the hydrogen fuel, which is a gaseous fuel, has a smaller ignition energy than the gasoline fuel, which is a liquid fuel, and the gasoline fuel, which is a liquid fuel, has a larger ignition energy than the hydrogen fuel, which is a gaseous fuel.

[0024] Also, as shown in FIG. 2, in the injection valve unit 40 of the present embodiment, the first injection valve 41a is disposed in the first intake port 22a, and the second injection valve 41b is disposed in the second intake port 22b. Therefore, in the first intake port 22a, hydrogen fuel injected from the first injection valve 41a is mixed with intake air to generate an air-fuel mixture, and the generated air-fuel mixture flows into the combustion chamber 19 through the first intake valve 24a. On the other hand, in the second intake port 22b, gasoline fuel injected from the second injection valve 41b is mixed with intake air to generate an air-fuel mixture, and the generated air-fuel mixture flows into the combustion chamber 19 through the second intake valve 24b. Therefore, in the engine 11 of the present embodiment, both hydrogen fuel and gasoline fuel flow into one combustion chamber 19. Note that the control device 60 controls the injection timing by the first injection valve 41a and the second injection valve 41b based on the crank angle information detected by the crank angle sensor 61.

[0025] Returning to FIG. 1, the engine 11 has a valve operating system 50. The valve operating system 50 is a system for opening and closing the intake valve unit 23 and the exhaust valve unit 33. Specifically, the valve operating system 50 includes an intake cam unit 51 for opening and closing the intake valve unit 23 and an exhaust cam unit 52 for opening and closing the exhaust valve unit 33. The valve operating system 50 of the present embodiment is a double overhead camshaft system in which the intake cam unit 51 and the exhaust cam unit 52 rotate integrally with camshafts rotatably supported by the cylinder head 14, respectively. The camshaft of the intake cam unit 51 and the camshaft of the exhaust cam unit 52 are connected to the crankshaft 16 via a cam chain and rotate in conjunction with the rotation of the crankshaft 16.

[0026] The intake valve portion 23 and the exhaust valve portion 33 are each opened by being pressed against the biasing force of the valve spring 53 by the intake cam portion 51 and the exhaust cam portion 52. On the other hand, the intake valve portion 23 and the exhaust valve portion 33 are each released from the pressing force by the intake cam portion 51 and the exhaust cam portion 52, and are closed by being returned to their original positions by the biasing force of the valve spring 53. By the operation of such a valve operating system 50, the opening and closing timing of the intake valve portion 23 and the exhaust valve portion 33 in the intake stroke, compression stroke, combustion stroke, and exhaust stroke of the engine 11 is controlled.

[0027] The engine 11 repeats four cycles of the intake stroke, compression stroke, combustion stroke, and exhaust stroke, and the driving force is transmitted from the engine body 12 to the drive wheels via the crankshaft 16, whereby the vehicle 10 travels.

[0028] Further, the engine 11 has a control device 60 as a control system. The control device 60 controls the entire vehicle 10 and the engine 11. The control device 60 can use, for example, an ECU (Electronic Control Unit). The control device 60 has a CPU, ROM, RAM, etc. as a hardware configuration. Programs and predetermined information for controlling the vehicle 10, the engine 11, etc. are stored in advance in the ROM. The RAM is a work memory and temporarily stores programs and data. The CPU reads out the programs stored in the ROM, expands them in the RAM, and executes them to control the vehicle 10, the engine 11, etc.

[0029] As described above, the engine 11 of the present embodiment that can simultaneously use a plurality of different fuels stabilizes combustion by allowing the fuel with a large ignition energy to flow into the combustion chamber 19 among the fuels injected from the plurality of injection valves (the first injection valve 41a and the second injection valve 41b). Hereinafter, specifically, a method of allowing the fuel with a large ignition energy to flow into the combustion chamber 19 will be described.

[0030] <Example 1> In the first embodiment, in order for the control device 60 to cause the fuel with high ignition energy to flow into the combustion chamber 19, the injection timings of a plurality of injection valves (the first injection valve 41a and the second injection valve 41b) are controlled. Here, when comparing hydrogen fuel and gasoline fuel, the fuel with high ignition energy is gasoline fuel. In the first embodiment, it is assumed that the valve operation system 50 is configured such that the first intake valve 24a and the second intake valve 24b open simultaneously.

[0031] In order for the control device 60 to cause the fuel with high ignition energy to flow into the combustion chamber 19, first, the second injection valve 41b is opened to inject gasoline fuel, so that the gasoline fuel with high ignition energy flows into the combustion chamber 19. Next, after the control device 60 opens the second injection valve 41b, the first injection valve 41a is opened to inject hydrogen fuel with low ignition energy, so that the hydrogen fuel flows into the combustion chamber 19 after the gasoline fuel.

[0032] FIG. 3 is a diagram for explaining the injection timings of the first injection valve 41a and the second injection valve 41b and the opening / closing timings of the intake valve portion 23 and the exhaust valve portion 33 in the first embodiment. In FIG. 3, the horizontal axis represents time or crank angle, and the top dead center of the piston is shown as TDC. The stroke before the top dead center is the exhaust stroke, and the stroke after the top dead center is the intake stroke.

[0033] In the exhaust stroke, the piston 17 rises from the bottom dead center toward the top dead center. As shown in FIG. 3, the exhaust valve portion 33 (the first exhaust valve 34a and the second exhaust valve 34b) is open during the exhaust stroke. On the other hand, the intake valve portion 23 (the first intake valve 24a and the second intake valve 24b) is almost closed during the exhaust stroke but opens just before the top dead center. Before the intake valve section 23 (the first intake valve 24a and the second intake valve 24b) opens during the exhaust stroke, the control device 60 opens the second injection valve 41b to inject gasoline fuel with high ignition energy, filling the second intake port 22b with a mixture of intake air and gasoline fuel. On the other hand, during the exhaust stroke, by not opening the first injection valve 41a, hydrogen fuel with low ignition energy is not injected.

[0034] In this way, by injecting gasoline fuel from the exhaust stroke, it is possible to easily allow only the gasoline fuel with high ignition energy to flow into the combustion chamber 19. Also, by injecting gasoline fuel from the exhaust stroke, it is possible to promote the mixing of the intake air and the gasoline fuel when it flows into the combustion chamber 19, or suppress the fuel shortage in the combustion chamber 19 when the engine load is large.

[0035] During the intake stroke, the piston 17 descends from top dead center to bottom dead center. As shown in FIG. 3, the exhaust valve section 33 (the first exhaust valve 34a and the second exhaust valve 34b) closes immediately after top dead center. On the other hand, the intake valve section 23 (the first intake valve 24a and the second intake valve 24b) is open during the intake stroke. After the intake valve section 23 (the first intake valve 24a and the second intake valve 24b) opens and a certain time has elapsed, the control device 60 opens the first injection valve 41a during the intake stroke to inject hydrogen fuel with low ignition energy, filling the first intake port 22a with a mixture of intake air and hydrogen fuel. In this embodiment, the injection timing for opening the first injection valve 41a to inject hydrogen fuel is substantially the same as the timing for closing the exhaust valve section 33 (the first exhaust valve 34a and the second exhaust valve 34b).

[0036] Therefore, until the intake valve portion 23 (the first intake valve 24a and the second intake valve 24b) opens and a certain period of time elapses, the air-fuel mixture of intake air and gasoline fuel in the second intake port 22b flows into the combustion chamber 19 through the second intake valve 24b of the intake valve portion 23. As a result, first, the gasoline fuel with high ignition energy flows into the combustion chamber 19. At this time, the ignition plug 20, the intake valve portion 23, and the exhaust valve portion 33 are cooled by the latent heat of vaporization of the gasoline fuel.

[0037] Subsequently, after the intake valve portion 23 (the first intake valve 24a and the second intake valve 24b) opens and a certain period of time elapses, the first injection valve 41a is opened to inject hydrogen fuel with low ignition energy. Thus, the air-hydrogen fuel mixture in the first intake port 22a flows into the combustion chamber 19 through the first intake valve 24a of the intake valve portion 23. Therefore, it is possible to cause the hydrogen fuel with low ignition energy to flow into the combustion chamber 19 after the gasoline fuel with high ignition energy.

[0038] Note that it is preferable that the air-fuel mixture flowing into the combustion chamber 19 does not flow back or remain in the intake port portion 21. That is, since the air-fuel mixture that flows back or remains in the intake port portion 21 contains hydrogen fuel with low ignition energy, if the air-fuel mixture containing hydrogen fuel flows into the combustion chamber 19 first in the next intake stroke, there is a possibility of premature ignition. Therefore, the control device 60 controls to close the first injection valve 41a and the second injection valve 41b to stop fuel injection while the intake valve portion 23 (the first intake valve 24a and the second intake valve 24b) is open, in other words, before closing. In this way, by stopping fuel injection before the intake valve portion 23 (the first intake valve 24a and the second intake valve 24b) closes, it is possible to prevent fuel from flowing back or remaining in the intake port portion 21.

[0039] According to the first embodiment as described above, by allowing gasoline fuel with high ignition energy to flow into the combustion chamber 19, the ignition plug 20, the intake valve portion 23, and the exhaust valve portion 33 are cooled by the latent heat of vaporization of the gasoline fuel. Therefore, since the premature ignition of the hydrogen fuel with low ignition energy in the combustion chamber 19 is alleviated, it is possible to suppress the combustion from becoming unstable.

[0040] In the first embodiment, the case where the intake port portion 21 has a plurality of intake ports (the first intake port 22a and the second intake port 22b) has been described. However, the present invention is not limited to this case, and the intake port portion 21 may be configured to have one intake port communicating with one combustion chamber 19. In this case, the intake valve portion 23 is configured to have one intake valve corresponding to one intake port. On the other hand, the injection valve portion 40 has a plurality of injection valves (the first injection valve 41a and the second injection valve 41b), and the first injection valve 41a and the second injection valve 41b can be arranged in one intake port.

[0041] In the first embodiment, the case where the control device 60 controls the injection timing by a plurality of injection valves (the first injection valve 41a and the second injection valve 41b) so that fuel with high ignition energy flows into the combustion chamber 19 has been described. On the other hand, in the case of operating conditions where premature ignition does not occur, the control device 60 may open the first injection valve 41a and the second injection valve 41b substantially simultaneously so that a plurality of fuels flow into the combustion chamber 19 at substantially the same timing.

[0042] <Second Embodiment> In the second embodiment, combustion is stabilized by opening a plurality of intake valves (the first intake valve 24a and the second intake valve 24b) so that the valve operation system 50 allows fuel with high ignition energy to flow into the combustion chamber 19. In order to introduce fuel with high ignition energy into the combustion chamber 19, the valve operating system 50 first opens the second intake valve 24b to allow gasoline fuel with high ignition energy injected from the second injection valve 41b to flow into the combustion chamber 19. Next, after opening the second intake valve 24b, the valve operating system 50 opens the first intake valve 24a to allow hydrogen fuel with low ignition energy injected from the first injection valve 41a to flow into the combustion chamber 19 after the gasoline fuel.

[0043] Figure 4(a) is a diagram for explaining the injection timing of the first injection valve 41a and the second injection valve 41b, and the opening and closing timing of the first intake valve 24a, the second intake valve 24b, and the exhaust valve section 33 in Embodiment 2. In Figure 4(a), the horizontal axis represents time or crank angle, and the top dead center of the piston is shown as TDC. The stroke before the top dead center is the exhaust stroke, and the stroke after the top dead center is the intake stroke.

[0044] In the exhaust stroke, the piston 17 rises from the bottom dead center toward the top dead center. As shown in Figure 4(a), the exhaust valve section 33 (the first exhaust valve 34a, the second exhaust valve 34b) is open during the exhaust stroke. The control device 60 first opens the second injection valve 41b to inject gasoline fuel with high ignition energy and fills the second intake port 22b with a mixture of intake air and gasoline fuel before the first intake valve 24a and the second intake valve 24b open in the exhaust stroke. Next, the control device 60 opens the first injection valve 41a to inject hydrogen fuel with low ignition energy and fills the first intake port 22a with a mixture of intake air and hydrogen fuel before the first intake valve 24a and the second intake valve 24b open. The valve operating system 50 first opens the second intake valve 24b before opening the first intake valve 24a. Here, the second intake valve 24b opens immediately before the top dead center.

[0045] In the intake stroke, the piston 17 descends from the top dead center toward the bottom dead center. As shown in Figure 4(a), the exhaust valve section 33 (the first exhaust valve 34a, the second exhaust valve 34b) closes immediately after the top dead center. Since the valve operating system 50 opens the second intake valve 24b, the air-fuel mixture of intake air and gasoline fuel in the second intake port 22b flows into the combustion chamber 19 through the second intake valve 24b of the intake valve section 23. Thus, first, the gasoline fuel with high ignition energy flows into the combustion chamber 19. Next, after the valve operating system 50 opens the second intake valve 24b, it opens the first intake valve 24a. Therefore, the air-fuel mixture of intake air and hydrogen fuel in the first intake port 22a flows into the combustion chamber 19 through the first intake valve 24a of the intake valve section 23. In this way, it is possible to make the hydrogen fuel with low ignition energy flow into the combustion chamber 19 after the gasoline fuel with high ignition energy. In this embodiment, the timing of opening the first intake valve 24a is immediately after closing the exhaust valve section 33 (the first exhaust valve 34a and the second exhaust valve 34b). Since the timing of closing the exhaust valve section 33 (the first exhaust valve 34a and the second exhaust valve 34b) is within the intake stroke, by opening the first intake valve 24a after closing the exhaust valve section 33, since the inside of the combustion chamber 19 is in a negative pressure, it is possible to suppress the backflow of the air-fuel mixture containing hydrogen fuel flowing into the combustion chamber 19 to the intake port section 21.

[0046] Also, in the same manner as in the first embodiment, in the second embodiment, while the first intake valve 24a and the second intake valve 24b are open, in other words, before closing, the control device 60 controls to close the first injection valve 41a and the second injection valve 41b to stop fuel injection. Therefore, it is possible to prevent fuel from flowing back or remaining in the intake port section 21.

[0047] FIG. 4(b) is a diagram showing the valve lift curves of the first intake valve 24a, the second intake valve 24b, and the exhaust valve section 33 in the exhaust stroke and the intake stroke. In FIG. 4(b), the horizontal axis represents the crank angle, and the vertical axis represents the valve lift amount. As shown in FIG. 4(b), although the valve operation system 50 opens the second intake valve 24b earlier than the first intake valve 24a, the timing for closing the first intake valve 24a and the second intake valve 24b is substantially the same. That is, the operating angle of the first intake valve 24a is smaller than the operating angle of the second intake valve 24b. In this way, by making the closing timing of the first intake valve 24a and the second intake valve 24b substantially the same, it is possible to prevent fuel from flowing back into the intake port portion 21.

[0048] Incidentally, the intake cam portion 51 of the valve operation system 50 of the second embodiment has a first intake cam that operates the first intake valve 24a and a second intake cam that operates the second intake valve 24b. The first intake cam and the second intake cam are formed such that the cam profiles are at the opening and closing timings of the first intake valve 24a and the second intake valve 24b shown in FIGS. 4(a) and 4(b), respectively. Therefore, in the valve operation system 50 of the second embodiment, the opening and closing timings by the first intake valve 24a and the second intake valve 24b described above can be realized.

[0049] As described above, according to the second embodiment, by flowing gasoline fuel with high ignition energy into the combustion chamber 19, the ignition plug 20, the intake valve portion 23, and the exhaust valve portion 33 are cooled by the latent heat of vaporization of the gasoline fuel. Therefore, since the premature ignition of the hydrogen fuel with low ignition energy in the combustion chamber 19 is alleviated, it is possible to suppress the combustion from becoming unstable.

[0050] Incidentally, in the second embodiment, the control device 60 controls the first injection valve 41a and the second injection valve 41b to open at different timings, but this is not limited to this case, and they may be controlled to open substantially simultaneously.

[0051] In addition, in the second embodiment, a case where the valve operating system 50 is a so-called fixed valve system configured to open the first intake valve 24a and the second intake valve 24b so that fuel with high ignition energy flows into the combustion chamber 19 was described. On the other hand, in the case of operating conditions where early ignition does not occur, the first intake valve 24a and the second intake valve 24b may be opened substantially simultaneously so that a plurality of fuels flow into the combustion chamber 19 at substantially the same timing. In this case, as shown in FIG. 5, it is preferable that the valve operating system is a so-called variable valve system that can vary the opening and closing timings of the first intake valve 24a and the second intake valve 24b.

[0052] FIG. 5 is a diagram showing a modified example of the second embodiment, and shows an engine 110 including a valve operating system 150 as a variable valve system. The valve operating system 150 includes an intake VVT mechanism 54 and an exhaust VVT mechanism 55 in addition to an intake cam portion 51 that opens and closes the intake valve portion 23 and an exhaust cam portion 52 that opens and closes the exhaust valve portion 33.

[0053] The intake VVT (Variable Valve Timing) mechanism 54 varies the opening and closing timing and the operating angle of the intake valve portion 23. Specifically, the intake VVT mechanism 54 changes the opening and closing timing and the operating angle to be different between the first intake valve 24a and the second intake valve 24b based on the control by the control device 60. Note that the intake VVT mechanism 54 may be configured to change the opening and closing timing and the operating angle of either one of the first intake valve 24a and the second intake valve 24b.

[0054] The exhaust VVT (Variable Valve Timing) mechanism 55 varies the opening and closing timing and the operating angle of the exhaust valve portion 33. Specifically, the exhaust VVT mechanism 55 changes the opening and closing timing and the operating angle to be different between the first exhaust valve 34a and the second exhaust valve 34b based on the control by the control device 60. Note that the exhaust VVT mechanism 55 may be configured to change the opening and closing timing and the operating angle of either one of the first exhaust valve 34a and the second exhaust valve 34b.

[0055] According to the engine 110 shown in FIG. 5, the control device 60 controls the intake VVT mechanism 54 of the valve operation system 150 under operating conditions where early ignition occurs. The intake VVT mechanism 54 controls the opening / closing timing and the operating angle of the first intake valve 24a and the second intake valve 24b to be the opening / closing timing and the operating angle shown in FIGS. 4(a) and 4(b) based on an instruction from the control device 60. Therefore, since the early ignition of the hydrogen fuel with low ignition energy in the combustion chamber 19 is alleviated, it is possible to suppress the combustion from becoming unstable.

[0056] As described above, the embodiments according to the present invention have been described. However, the present invention is not limited to the above-described embodiments, and modifications and the like are possible within the scope of the present invention.

[0057] In the above-described embodiments, the case where hydrogen fuel is used as the fuel with low ignition energy and gasoline fuel is used as the fuel with high ignition energy has been described. However, it is not limited to this case. For example, an engine that can simultaneously use hydrogen fuel as the fuel with low ignition energy and compressed natural gas (CNG) as the fuel with high ignition energy may be used, or an engine that can simultaneously use other combinations of fuels may be used.

[0058] In the above-described embodiments, the case where the valve operation systems 50 and 150 are of the double overhead camshaft type has been described. However, it is not limited to this case. The valve operation systems 50 and 150 only need to be able to realize the operation of the intake valve portion 23 of the above-described embodiments, and any type of valve operation system may be used.

Explanation of Reference Numerals

[0059] 10: Vehicle 11, 110: Engine 17: Piston 19: Combustion chamber 20: Spark plug 21: Intake port section 22a: First intake port 22b: Second intake port 23: Intake valve section 24a: First intake valve 24b: Second intake valve 31: Exhaust port section 40: Injection valve section 41a: First injection valve 41b: Second injection valve 50, 150: Valve actuation system 51: Intake cam section 61: Exhaust cam section 60: Control device

Claims

1. An internal combustion engine capable of simultaneously using a plurality of different fuels, comprising a plurality of injection valves each injecting a different fuel so as to cause the different fuels to flow into one combustion chamber, wherein the fuel having a larger ignition energy among the fuels injected from the plurality of injection valves is caused to flow into the combustion chamber.

2. having a control device for controlling an injection timing for injecting fuel to the plurality of injection valves, wherein the control device controls the injection timing by the plurality of injection valves so that the fuel having a larger ignition energy flows into the combustion chamber. The internal combustion engine according to claim 1.

3. a plurality of intake ports communicating with the one combustion chamber, a plurality of intake valves corresponding to the plurality of intake ports, and a valve operating system for opening and closing the plurality of intake valves at different timings, wherein the plurality of injection valves are respectively arranged in the plurality of intake ports, and the valve operating system opens the plurality of intake valves so that the fuel having a larger ignition energy flows into the combustion chamber. The internal combustion engine according to claim 1.

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