internal combustion engine

Abstract

To prevent a reduction in an intake air amount in an internal combustion engine injecting gaseous fuel into an intake port.SOLUTION: An internal combustion engine 1 comprises a plurality of intake ports 9, in a cylinder, configured as tumble ports that generate tumble flow inside the cylinder. Gaseous fuel is injected through a port injection valve 36 into some of the plurality of intake ports 9 in a period other than a period when an intake valve 12 of the internal combustion engine 1 is closed. A fuel injection direction of the port injection valve 36 opposes a direction of the tumble flow, which moves from a piston 5 toward the intake valve 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] The internal combustion engine described in Patent Document 1 has a plurality of intake ports in each cylinder, and this internal combustion engine injects gaseous fuel into some of the intake ports during the period from when the exhaust valve closes to when the intake valve closes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-52665 [Patent Document 2] Japanese Patent Application Publication No. 2018-131947 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as described in Patent Document 2, when gaseous fuel is injected into an intake port, the gaseous fuel impedes the movement of air within the intake port, which may result in a decrease in the amount of intake air into the internal combustion engine compared to when gaseous fuel is not used. [Means for solving the problem]

[0005] An internal combustion engine that solves the above problem includes a plurality of intake ports configured as tumble ports that generate a tumble flow within the cylinder, and injects gaseous fuel from injection valves provided in some of the intake ports during periods that do not include periods when the intake valves of the engine are closed, and the fuel injection direction of the injection valves is set to a direction opposite to the flow direction of the tumble flow that flows from the piston side to the intake valve side of the engine. [Effects of the Invention]

[0006] This internal combustion engine can suppress a decrease in the amount of intake air in an internal combustion engine that injects gaseous fuel into an intake port. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view of an internal combustion engine according to one embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the arrangement of injection valves provided in the internal combustion engine of the embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view of the internal combustion engine of the embodiment. [Figure 4] FIG. 4 is a schematic diagram showing the arrangement of injection valves in a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] An internal combustion engine according to an embodiment will now be described with reference to FIGS. <Configuration of an internal combustion engine> As shown in Fig. 1, a cylindrical cylinder 4 is provided in a cylinder block 2 of an internal combustion engine 1. A piston 5 that reciprocates is provided within the cylinder 4.

[0009] A cylinder head 3 is attached to the top of the cylinder block 2. A combustion chamber 8 is formed in each cylinder 4 between the top surface of the piston 5 and the cylinder head 3. In addition, the cylinder head 3 is provided with a spark plug 11 for each cylinder of the internal combustion engine 1, which spark-ignites the air-fuel mixture in the combustion chamber 8.

[0010] The cylinder head 3 is also provided with an intake port 9 that introduces intake air into the combustion chamber 8 and an exhaust port 10 that discharges exhaust gas from the combustion chamber 8. The intake port 9 is provided with an intake valve 12 that opens and closes the intake port 9. The cylinder head 3 is also provided with a port injection valve 36 that injects hydrogen gas, which is a gaseous fuel, into the intake port 9.

[0011] As shown in Figure 2, two intake ports 9 are connected to one combustion chamber 8. Each intake port 9 is configured as a tumble port that generates a tumble flow inside the cylinder. One of the two intake ports 9 is provided with the port injection valve 36. Therefore, gaseous fuel FL and air flow into the cylinder 4 from the intake port 9 provided with the port injection valve 36. On the other hand, air AR flows into the cylinder 4 from the intake port 9 not provided with the port injection valve 36.

[0012] As shown in FIG. 1, the exhaust port 10 is provided with an exhaust valve 13 that opens and closes the exhaust port 10 . The fuel injection direction of the gaseous fuel FL injected from the port injection valve 36 is set in a direction opposite to the flow direction of the tumble flow T of the air AR or mixture generated in the cylinder 4, which flows from the piston 5 side to the intake valve 12 side.

[0013] Various controls of the internal combustion engine 1 are executed by a control device 100. The control device 100 includes a CPU, a memory in which control programs and the like are stored, and the like. The CPU executes the programs stored in the memory to perform various controls of the internal combustion engine 1. For example, the control device 100 controls the fuel injection amount and injection timing of the port injection valve 36. As an example, the control device 100 of this embodiment controls the injection timing of the port injection valve 36 so that the gaseous fuel is injected during a period that avoids the closing period of the intake valve 12. More specifically, the control device 100 starts injection of the gaseous fuel FL from the port injection valve 36 simultaneously with the opening of the intake valve 12. Then, the control device 100 stops injection of the gaseous fuel FL before the intake valve 12 closes.

[0014] The control device 100 also calculates an engine load factor KL based on the engine speed and the amount of intake air drawn into the cylinders of the internal combustion engine 1. The engine load factor KL represents the ratio of the current amount of air flowing into the cylinder to the amount of air flowing into the cylinder when the engine is operated at full load at the current engine speed. The amount of air flowing into the cylinder is the amount of air flowing into the cylinder during the intake stroke.

[0015] <effect> The operation of this embodiment will be described. As shown in Figure 3, if gaseous fuel FL is injected into the intake port 9 while the intake valve 12 is closed, the injected gaseous fuel FL will remain in the intake port 9 until the intake valve 12 opens, as indicated by the dashed dotted line. Immediately after the intake valve 12 opens, the remaining gaseous fuel FL will first flow into the cylinder. After the remaining gaseous fuel FL has flowed into the cylinder, air AR will flow into the cylinder. Therefore, the intake air amount is more likely to decrease than when air flows into the cylinder immediately after the intake valve 12 opens.

[0016] In this embodiment, the gaseous fuel FL is injected from the port injection valve 36 during a period that does not include the closing period of the intake valve 12. Therefore, the gaseous fuel FL does not accumulate in the intake port 9, and when the intake valve 12 opens, the air in the intake port 9 quickly flows into the cylinder.

[0017] 1 and 2, air flows into the cylinder during the intake stroke from one of the two intake ports 9 provided in the cylinder that is not provided with a port injection valve 36 and does not inject the gaseous fuel FL. On the other hand, the fuel injection direction of the port injection valve 36 provided in the intake port 9 that injects the gaseous fuel FL is set to be opposite to the flow direction of the tumble flow T that flows from the piston 5 side to the intake valve 12 side. Therefore, the inflow resistance of the gaseous fuel FL injected from the port injection valve 36 into the cylinder increases. If the inflow resistance of the gaseous fuel FL into the cylinder increases, air is more likely to flow into the cylinder from the other intake port 9 that is not injected with the gaseous fuel FL.

[0018] Incidentally, the injection pressure of the gaseous fuel FL is sufficiently higher than the dynamic pressure of the air in the cylinder. Therefore, even if the inflow resistance of the gaseous fuel FL when it flows into the cylinder increases, the necessary amount of gaseous fuel FL can be supplied to the cylinder.

[0019] <Effects> The effects of this embodiment will be described. (1) By injecting the gaseous fuel FL from the port injection valve 36 during a period that does not involve the closing of the intake valve 12, the gaseous fuel FL does not accumulate in the intake port 9. When the intake valve 12 opens, air quickly flows into the cylinder from the intake port 9. This makes it possible to suppress a decrease in the amount of intake air.

[0020] In addition, as the inflow resistance when the gaseous fuel FL flows into the cylinder increases, air is more likely to flow into the cylinder from the other intake port 9 where the gaseous fuel FL is not injected, and the amount of intake air increases.

[0021] Therefore, in the internal combustion engine 1 that injects the gaseous fuel FL into the intake port 9, a decrease in the amount of intake air can be suppressed. (2) In order to inject the gaseous fuel FL from the port injection valve 36 during a period that does not involve the closing of the intake valve 12, the port injection valve 36 starts injecting the gaseous fuel FL simultaneously with the opening of the intake valve 12. Therefore, the gaseous fuel FL does not accumulate in the intake port 9, and when the intake valve 12 opens, the air in the intake port 9 quickly flows into the cylinder. This makes it possible to suppress a decrease in the amount of intake air.

[0022] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0023] As shown in Fig. 4, the port injection valve 36 that injects gaseous fuel FL is provided in one of the intake ports 9. Then, another port injection valve 38 that injects fuel in a direction different from that of the port injection valve 36 may be provided in the other intake port 9. In this case, the gaseous fuel FL is injected from the port injection valve 36 when the following condition is met:

[0024] That is, when the engine load factor KL of the internal combustion engine 1 is high, the amount of gaseous fuel FL injected into the intake port 9 increases. Therefore, when the engine load factor KL is high and the gaseous fuel FL is injected into the intake port 9 while the intake valve 12 is closed, the amount of gaseous fuel FL remaining in the intake port 9 increases. Therefore, immediately after the intake valve 12 opens, air is even less likely to flow into the cylinder, and the intake air amount is more likely to decrease. Therefore, when the engine load factor KL is equal to or higher than a predetermined threshold and is high, the gaseous fuel FL is injected only from the port injection valve 36, avoiding the period when the intake valve 12 is closed. This modification also achieves the effects described in (1) and (2) above. Note that in this modification, when the engine load factor KL is less than the threshold, the gaseous fuel may be injected from both the port injection valve 36 and the port injection valve 38. The fuel injection direction of the port injection valve 38 may be the same as that of the port injection valve 36. In this modification and the above embodiment, the number of intake ports 9 provided in one cylinder may be changed arbitrarily as long as it is equal to or greater than 2. When one cylinder has multiple intake ports 9, the port injection valves 36 may be provided in some of the intake ports 9, and the gaseous fuel FL may be injected from the port injection valves 36 during a period other than the period when the intake valve 12 is closed.

[0025] In the above embodiment, when the engine load factor KL is equal to or higher than the threshold value and is therefore high, the gaseous fuel FL is injected from the port injection valve 36 during a period that avoids the closing period of the intake valve 12. On the other hand, when the engine load factor KL is lower than the threshold value and is therefore low, the gaseous fuel FL may be injected from the port injection valve 36 during a period that includes the closing period of the intake valve 12.

[0026] In the above embodiment, the injection of the gaseous fuel FL from the port injection valve 36 begins simultaneously with the opening of the intake valve 12. Alternatively, the injection of the gaseous fuel FL from the port injection valve 36 may begin after the intake valve 12 begins to open. Even in this case, the gaseous fuel FL does not accumulate in the intake port 9, and when the intake valve 12 opens, air quickly flows into the cylinder from the intake port 9. This makes it possible to suppress a decrease in the amount of intake air.

[0027] In addition to the port injection valve 36, the internal combustion engine 1 may be provided with an injection valve that injects liquid fuel. The gaseous fuel is hydrogen gas, but other gaseous fuels, such as compressed natural gas, may also be used. [Explanation of symbols]

[0028] 1...Internal combustion engine 2...Cylinder block 3...Cylinder head 4...Cylinder 5...Piston 8...Combustion chamber 9...Intake port 10...Exhaust port 11...Spark plug 12...Intake valve 13...Exhaust valve 36...Port injection valve 38...Port injection valve 100...Control device

Claims

1. An internal combustion engine having a plurality of intake ports configured as tumble ports that generate tumble flow in the cylinder, an injection valve for injecting gaseous fuel is provided in each of the plurality of intake ports; Injecting gaseous fuel from an injection valve into some of the intake ports of the plurality of intake ports during a period other than a closing period of an intake valve of the internal combustion engine; a fuel injection direction of the injection valve is set in a direction opposite to a flow direction of the tumble flow that flows from a piston side to an intake valve side of the internal combustion engine, at least some of the injection valves provided in the plurality of intake ports inject gaseous fuel into the intake ports during periods other than the closing periods of the intake valves, and the fuel injection direction is set in a direction opposite to the flow direction of the tumble flow flowing from the piston side to the intake valve side, When the engine load factor is equal to or greater than a predetermined threshold, the gaseous fuel is injected into the intake port from only the part of the injection valves. Internal combustion engine.

2. The injection valve that injects the gaseous fuel into the part of the intake ports starts injecting the gaseous fuel simultaneously with the opening of the intake valve.

2. The internal combustion engine according to claim 1.

3. The injection valve that injects the gaseous fuel into the part of the intake ports starts injecting the gaseous fuel after the intake valve starts opening.

2. The internal combustion engine according to claim 1.

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