Internal combustion engine, and method for controlling internal combustion engine

Abstract

To appropriately mix fuel and compressed air.SOLUTION: An internal combustion engine 1 has: a fuel injection unit 26 that is provided in a cylinder head 21, and injects fuel into a combustion chamber 22; a high-pressure chamber 311 to which compressed air from the combustion chamber 22 is supplied during a compression stroke, and that is capable of further compressing the compressed air; and an air injection unit that is provided around the fuel injection unit 26 in the cylinder head 21, and injects the compressed air compressed in the high-pressure chamber 311 when the fuel injection unit 26 injects fuel.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an internal combustion engine which injects compressed air into a combustion chamber of the engine, and a method for controlling the internal combustion engine. [Background technology]

[0002] There is known a technique for injecting compressed air into a combustion chamber of an engine. For example, Patent Document 1 discloses a technique for injecting compressed air into a combustion chamber after fuel is injected into the combustion chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-325748 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, simply supplying compressed air may not result in the fuel and compressed air being mixed properly depending on the location within the combustion chamber.

[0005] The present invention has been made in consideration of these points, and has an object to appropriately mix fuel and compressed air. [Means for solving the problem]

[0006] In a first aspect of the present invention, there is provided an internal combustion engine having a fuel injection unit provided in a cylinder head for injecting fuel into a combustion chamber, a high-pressure chamber to which compressed air from the combustion chamber is supplied during a compression stroke and capable of further compressing the compressed air, and an air injection unit provided in the cylinder head around the fuel injection unit for injecting the compressed air compressed in the high-pressure chamber when the fuel injection unit injects the fuel.

[0007] The air injection unit may have a piston slidably arranged within the high-pressure chamber, and when the fuel injection unit injects the fuel, the piston may be slid to further compress the compressed air in the high-pressure chamber, and the compressed air may be injected into the combustion chamber.

[0008] The internal combustion engine may have a low pressure chamber provided on the opposite side of the high pressure chamber across the piston, and a supply control unit that supplies air to the low pressure chamber to slide the piston when the fuel injection unit injects the fuel.

[0009] The piston may have a compression section housed in the high-pressure chamber and capable of compressing the compressed air, and a pressure-receiving section connected to the compression section, and an area of ​​a first surface of the pressure-receiving section that receives the pressure of the air in the low-pressure chamber may be larger than an area of ​​a second surface of the compression section that pressurizes the compressed air in the high-pressure chamber.

[0010] The supply control unit may remove the air from the low pressure chamber during an intake stroke immediately after injecting the compressed air.

[0011] The piston may slide so that a volume of the high-pressure chamber increases when the compressed air compressed in the combustion chamber is supplied to the high-pressure chamber after the intake stroke has been completed and the compression stroke has been completed.

[0012] The air injection section may inject the compressed air from an injection nozzle that connects the high-pressure chamber and the combustion chamber and is inclined with respect to a lower surface of the cylinder head, toward a gap between the fuel injected into the combustion chamber and the cylinder head.

[0013] In a second aspect of the present invention, there is provided a control method for an internal combustion engine having a cylinder head and a combustion chamber, comprising the steps of: supplying compressed air compressed in the combustion chamber to a high-pressure chamber capable of further compressing the air during a compression stroke; a fuel injection unit provided in the cylinder head injecting fuel into the combustion chamber; and an air injection unit provided in the cylinder head around the fuel injection unit injecting the compressed air compressed in the high-pressure chamber into the combustion chamber when the fuel injection unit injects the fuel. Effect of the Invention

[0014] According to the present invention, it is possible to appropriately mix the fuel and the compressed air. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a diagram for explaining the configuration of an engine. [Diagram 2] FIG. 2 is a schematic diagram of a combustion chamber as viewed from the cylinder head side. [Diagram 3] 3A and 3B are diagrams for explaining the configuration of an air injection device. [Figure 4] FIG. 2 is a diagram for explaining an injection cycle of compressed air. [Diagram 5] 10 is a flowchart illustrating an example of a process for ejecting compressed air. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [Configuration of internal combustion engine 1] 1 is a diagram for explaining the configuration of an internal combustion engine 1. The internal combustion engine 1 is an internal combustion engine that generates power by burning and expanding a mixture of fuel and intake air (air). The internal combustion engine 1 is, for example, a diesel engine installed in an automobile or a ship.

[0017] The internal combustion engine 1 has a cylinder 2, a piston 23 that moves up and down inside the cylinder 2, and a cylinder head 21 provided at one end of the cylinder 2. The internal combustion engine 1 has two or more combinations of the cylinder 2 and the piston 23. Note that the internal combustion engine 1 may be a so-called single-cylinder engine that has one combination of the cylinder 2 and the piston 23. The cylinder head 21 is provided with an intake valve 24, an exhaust valve 25, a fuel injection unit 26, and an air injection device 3.

[0018] In the combustion cycle of the internal combustion engine 1, when the piston 23 descends, the intake valve 24 opens, and air (intake air) is drawn from the intake pipe 11 into the combustion chamber 22 of the cylinder 2 (intake stroke). Next, when the piston 23 reaches the bottom dead center, the intake valve 24 closes, and when the piston 23 ascends to the top dead center, the air is compressed (compression stroke).

[0019] Next, fuel 4 is injected by a fuel injection unit 26 provided in the cylinder head 21 for injecting fuel into the combustion chamber 22, the fuel mixed with the compressed air is burned, and the expanding combustion gas pushes the piston 23 down to the bottom dead center (combustion stroke). Then, when the piston 23 rises again to the top dead center due to inertia and expansion in other cylinders 2, the exhaust valve 25 is opened, and the combustion gas is pushed out of the combustion chamber 22 and discharged from the exhaust pipe 12 as exhaust gas (exhaust stroke).

[0020] Incidentally, in the combustion chamber 22, the space between the cylinder head 21 and the injected fuel 4 is narrower than the space between the piston 23 and the fuel 4, so the amount of air present between the cylinder head 21 and the fuel 4 is less than the amount of air between the piston 23 and the fuel 4. Therefore, when the fuel 4 is injected, not enough air is taken in the fuel 4 on the cylinder head 21 side of the fuel 4, so the fuel and compressed air cannot be mixed properly.

[0021] Therefore, the internal combustion engine 1 has an air injection device 3 that injects compressed air between the cylinder head 21 and the injected fuel 4. The air injection device 3 is provided around the fuel injection unit 26 in the cylinder head 21. Fig. 2 is a schematic diagram of the combustion chamber 22 as viewed from the cylinder head 21 side. As shown in Fig. 2, the air injection device 3 is provided in a region including the center of a line segment D that connects the fuel injection unit 26 and the inner wall of the combustion chamber 22, but is not limited to this.

[0022] The air injection device 3 temporarily stores the compressed air compressed in the combustion chamber 22 during the compression stroke in the high pressure chamber 311, and further compresses the stored compressed air to inject it into the combustion chamber 22. This enables the internal combustion engine 1 to supply compressed air 5 to the cylinder head 21 side of the fuel 4 as well. As a result, the amount of air taken into the fuel 4 on the cylinder head 21 side increases, so that the fuel 4 and the compressed air 5 are appropriately mixed.

[0023] 3 is a diagram for explaining the configuration of the air injection device 3. The air injection device 3 has an air injection section 31, a high pressure chamber 311, and an injection nozzle 313.

[0024] The injection nozzle 313 communicates the high pressure chamber 311 with the combustion chamber 22. The injection nozzle 313 is provided at an incline with respect to the lower surface 21a of the cylinder head 21. Specifically, the injection nozzle 313 is provided at an incline with respect to the lower surface 21a of the cylinder head 21 so that the compressed air 5 can be injected toward between the fuel 4 injected into the combustion chamber 22 and the cylinder head 21. More specifically, the injection nozzle 313 is provided at an incline, preferably 45 degrees or less, more preferably 30 degrees or less, with respect to the lower surface 21a. As a result, the compressed air 5 is supplied to the space between the cylinder head 21 and the injected fuel 4, so that sufficient air is entrained in the fuel 4 even on the cylinder head 21 side of the fuel 4, and the internal combustion engine 1 can appropriately mix the fuel and the compressed air. The injection nozzle 313 injects the compressed air from the high pressure chamber 311 while the fuel 4 is being injected.

[0025] The injection nozzle 313 is provided so as to inject the compressed air 5 at a position that does not block the injected fuel 4. For example, the injection nozzle 313 is provided so that the axis of the compressed air 5 injected from the injection nozzle 313 does not intersect with the axis of the injected fuel 4. Specifically, the injection nozzle 313 is provided so that the fuel 4 injected from the fuel injection unit 26 and the compressed air 5 injected from the injection nozzle 313 are in a twisted position. As a specific example, as shown in FIG. 2, the compressed air 5 is injected in a direction inclined by a predetermined angle with respect to the fuel injection direction (for example, the direction of the line segment D). In this way, it is possible to prevent the injected compressed air 5 from blocking the injected fuel 4. Then, the fuel 4 is appropriately sprayed into the combustion chamber 22, and the fuel 4 and the compressed air 5 can be appropriately mixed. Note that the injection nozzle 313 of this embodiment injects the compressed air 5 in two directions as shown in FIG. 2, but the injection direction is not limited to two directions, and may be one direction or three or more directions.

[0026] The high pressure chamber 311 is supplied with compressed air from the combustion chamber 22 during the compression stroke. Specifically, the compressed air compressed in the combustion chamber 22 during the compression stroke is supplied to the high pressure chamber 311 through the injection nozzle 313. The shape of the high pressure chamber 311 is preferably cylindrical, but does not have to be cylindrical.

[0027] The air injection section 31 has a piston 312 and a low pressure chamber 314. The piston 312 has a compression section 312a accommodated in the high pressure chamber 311 and a pressure receiving section 312b connected to the compression section 312a. The compression section 312a of the piston 312 is provided so as to be able to slide within the high pressure chamber 311. The compression section 312a is in close contact with the inner wall of the high pressure chamber 311 so that the air in the high pressure chamber 311 does not leak. The compression section 312a of this embodiment has a cylindrical shape that is in close contact with the inner wall of the high pressure chamber 311, which is cylindrical. The second surface Sa of the compression section 312a receives the pressure of the compressed air in the high pressure chamber 311. In addition, the second surface Sa pressurizes the compressed air in the high pressure chamber 311 when the piston 312 slides so that the volume of the high pressure chamber 311 becomes smaller.

[0028] The low pressure chamber 314 is provided on the opposite side of the high pressure chamber 311 with the piston 312 in between. The low pressure chamber 314 has, for example, a cylindrical shape. The low pressure chamber 314 is connected to the pump 315 by an air supply pipe 316. The low pressure chamber 314 receives a supply of air from the pump 315. The pump 315 is a pump that supplies air to the low pressure chamber 314. The pump 315 is, for example, a gear pump. The pump 315 can suck air out of the low pressure chamber 314 by reversing its operation. The pump 315 is controlled by the injection control device 7.

[0029] The pressure receiving portion 312b is provided so as to be able to slide within the low pressure chamber 314. The pressure receiving portion 312b is in close contact with the inner wall of the low pressure chamber 314 so as to prevent air from leaking from the low pressure chamber 314. The pressure receiving portion 312b receives the pressure of the air within the low pressure chamber 314. Specifically, the first surface Sb of the pressure receiving portion 312b receives the pressure of the air within the low pressure chamber 314 when air is supplied from the pump 315 to the low pressure chamber 314. The shape of the pressure receiving portion 312b may be determined according to the shape of the low pressure chamber 314, and is a columnar shape if the low pressure chamber 314 is cylindrical.

[0030] The diameter LB of the cylindrical pressure receiving portion 312b is larger than the diameter LA of the cylindrical compression portion 312a. In other words, the area of ​​the first surface Sb of the pressure receiving portion 312b is larger than the area of ​​the second surface Sa of the compression portion 312a.

[0031] The injection control device 7 has a storage unit 71 and a control unit 72. The storage unit 71 is a storage medium including a ROM (Read Only Memory), a RAM (Random Access Memory), a hard disk, etc. The storage unit 71 stores a program executed by the control unit 72.

[0032] The control unit 72 is a computation resource including a processor such as a CPU (Central Processing Unit). The control unit 72 executes a program stored in the storage unit 71 to realize functions as an acquisition unit 721 and a supply control unit 722.

[0033] When fuel is injected from the fuel injection unit 26, the acquisition unit 721 acquires injection information indicating that fuel has been injected. For example, the acquisition unit 721 acquires the injection information from the fuel injection unit 26 or a control device that controls the fuel injection unit 26. The acquisition unit 721 also acquires the crank angle of the piston 23. Specifically, the acquisition unit 721 acquires angle information indicating the crank angle from a sensor that detects the crank angle of the piston 23.

[0034] The supply control unit 722 controls the pump 315 to supply air to the low pressure chamber 314, thereby sliding the piston 312 so that the volume of the high pressure chamber 311 becomes smaller, and injects compressed air. The supply control unit 722 supplies air to the low pressure chamber 314 in accordance with the combustion cycle of the internal combustion engine 1. In other words, the combustion cycle and the injection cycle in which air is supplied and compressed air is injected are linked. FIG. 4 is a diagram for explaining the injection cycle of compressed air. When the combustion cycle of the internal combustion engine 1 changes from the intake stroke to the compression stroke, air is not supplied to the low pressure chamber 314, and the pressure of the air in the low pressure chamber 314 is, for example, atmospheric pressure or lower.

[0035] When the combustion cycle of the internal combustion engine 1 is moving from the intake stroke to the compression stroke, compressed air is supplied to the high pressure chamber 311 (FIG. 4(1)). At this time, when the compressed air compressed in the combustion chamber 22 is supplied to the high pressure chamber 311, the piston 312 slides so as to increase the volume of the high pressure chamber 311 (FIG. 4(2)). Specifically, when the pressure applied by the compressed air filled in the high pressure chamber 311 to the second surface Sa of the compression section 312a becomes higher than the pressure applied by the air in the low pressure chamber 314 to the first surface Sb of the pressure receiving section 312b, the piston 312 slides so as to increase the volume of the high pressure chamber 311. More specifically, the pressure receiving section 312b and the compression section 312a of the piston 312 slide together so as to decrease the volume of the low pressure chamber 314 and increase the volume of the high pressure chamber 311.

[0036] When the fuel injection unit 26 injects fuel, the supply control unit 722 supplies air to the low pressure chamber 314. Specifically, when the injection information is acquired, the supply control unit 722 operates the pump 315 to supply air to the low pressure chamber 314.

[0037] When air is supplied to the low pressure chamber 314, the pressure that the first surface Sb of the pressure receiving portion 312b receives from the air in the low pressure chamber 314 increases. When more air is supplied to the low pressure chamber 314 and the force (pressure x area) received by the first surface Sb becomes greater than the force (pressure x area) received by the second surface Sa of the compression portion 312a, the piston 312 slides so that the volume of the low pressure chamber 314 increases and the volume of the high pressure chamber 311 decreases. Specifically, the pressure receiving portion 312b and the compression portion 312a of the piston 312 slide together so that the volume of the low pressure chamber 314 increases and the volume of the high pressure chamber 311 decreases. In other words, the compressed air in the high pressure chamber 311 is pressurized by the second surface Sa of the compression portion 312a and further compressed. When the pressure of the compressed air in the high pressure chamber 311 becomes higher than the pressure of the compressed air in the combustion chamber 22, the compressed air in the high pressure chamber 311 is injected into the combustion chamber 22. In this way, the supply control unit 722 supplies air to the low pressure chamber 314, causing the air in the low pressure chamber 314 to slide the piston 312 so as to reduce the volume of the high pressure chamber 311, thereby further compressing the compressed air in the high pressure chamber 311, and injecting the compressed air into the combustion chamber 22 ((3) in FIG. 4).

[0038] As described above, the area of ​​the first surface Sb of the pressure receiving portion 312b is larger than the area of ​​the second surface Sa of the compression portion 312a. Therefore, even if the first pressure per unit area of ​​the air in the low pressure chamber 314 is smaller than the second pressure per unit area of ​​the compressed air in the high pressure chamber 311, it is possible to make the force (pressure x area) received by the first surface Sb larger than the force (pressure x area) received by the second surface Sa. For example, when the area of ​​the first surface Sb is twice the area of ​​the second surface Sa, if the first pressure is larger than half the second pressure, the total pressure received by the first surface Sb is larger than the total pressure received by the second surface Sa. In other words, the supply control portion 722 does not need to make the first pressure of the air in the low pressure chamber 314 larger than the second pressure of the compressed air in the high pressure chamber 311 in order to slide the piston 312 so that the volume of the high pressure chamber 311 becomes smaller. This enables the supply control unit 722 to inject compressed air into the combustion chamber 22 with less energy than is required to make the air pressure in the low pressure chamber 314 greater than the pressure of the compressed air in the high pressure chamber 311.

[0039] After the fuel and compressed air are injected during the compression stroke, the mixture of fuel and compressed air is further compressed, and when the temperature of the mixture exceeds the ignition point, the mixture is burned and the combustion stroke begins. When there is no combustible mixture gas left in the combustion chamber 22, the pressure in the combustion chamber 22 drops ((4) in FIG. 4).

[0040] After injecting the compressed air during the compression stroke, the supply control unit 722 determines whether the combustion cycle of the internal combustion engine 1 has entered the intake stroke immediately after the injection of the compressed air, based on the crank angle acquired by the acquisition unit 721. When the intake stroke immediately after the injection of the compressed air has begun, the supply control unit 722 removes the air from the low pressure chamber 314 ((5) in FIG. 4). Specifically, the supply control unit 722 reverses the operation of the pump 315, which is a gear pump, to discharge the air in the low pressure chamber 314 to the outside of the low pressure chamber 314. More specifically, the supply control unit 722 discharges the air in the low pressure chamber 314 to the outside of the low pressure chamber 314 until the force exerted by the air in the low pressure chamber 314 on the first surface Sb becomes smaller than the force exerted by the compressed air supplied to the high pressure chamber 311 during the compression stroke on the second surface Sa.

[0041] When the intake stroke begins, the supply control unit 722 removes air from the low pressure chamber 314, thereby reducing the pressure on the first surface Sb of the pressure receiving unit 312b. When the combustion cycle of the internal combustion engine 1 enters the compression stroke again and the force on the second surface Sa of the compression unit 312a becomes greater than the force on the first surface Sb, the high pressure chamber 311 slides to increase its volume and compressed air is supplied to the high pressure chamber 311, so that the high pressure chamber 311 is filled with compressed air again. In this way, the supply control unit 722 repeatedly supplies air to and removes air from the low pressure chamber 314, thereby allowing the compressed air to be appropriately injected into the combustion chamber 22 in conjunction with the combustion cycle.

[0042] [Compressed air injection process] 5 is a flow chart showing an example of a process for injecting compressed air. The process for injecting compressed air is repeatedly executed while the internal combustion engine 1 is running.

[0043] The supply control unit 722 determines whether or not fuel has been injected into the combustion chamber 22 during the compression stroke (step S1). For example, when the acquisition unit 721 acquires injection information, the supply control unit 722 determines that fuel has been injected. When the acquisition unit 721 has not acquired injection information, the supply control unit 722 determines that fuel has not been injected (No in step S1) and waits until the acquisition unit 721 acquires the injection information.

[0044] If fuel is injected into the combustion chamber 22 during the compression stroke (Yes in step S1), the supply control unit 722 injects compressed air into the combustion chamber 22 (step S2). Specifically, the supply control unit 722 operates the pump 315 to supply air to the low pressure chamber 314. As a result, the piston 312 slides to increase the volume of the high pressure chamber 311, further compressing the compressed air in the high pressure chamber 311, and the compressed air in the high pressure chamber 311 is injected into the combustion chamber 22.

[0045] After injecting the compressed air, the supply control unit 722 judges whether the intake stroke has started (step S3). Specifically, the supply control unit 722 judges whether the combustion cycle of the internal combustion engine 1 has started the intake stroke immediately after injecting the compressed air, based on the crank angle acquired by the acquisition unit 721. If the intake stroke has not started (No in step S3), the supply control unit 722 waits until the intake stroke starts. If the intake stroke has started (Yes in step S3), the supply control unit 722 removes the air from the low pressure chamber 314 (step S4). Specifically, the supply control unit 722 rotates the pump 315 in the reverse direction to suck out the air from the low pressure chamber 314, thereby removing the air from the low pressure chamber 314.

[0046] (Variation 1) The internal combustion engine 1 in the embodiment is provided with only one air injection device 3. However, the present invention is not limited to this, and a plurality of air injection devices 3 may be provided in the internal combustion engine 1. For example, when two air injection devices 3 are provided, it is preferable that each of the plurality of air injection devices 3 is provided on the opposite side of the fuel injection unit 26. Furthermore, when three air injection devices 3 are provided, it is preferable that each of the plurality of air injection devices 3 is provided at the apex position of an equilateral triangle with the fuel injection unit 26 as the center of gravity. This enables the internal combustion engine 1 to supply compressed air between the injected fuel 4 and the cylinder head 21 without bias.

[0047] (Variation 2) In the air injection device 3 of the internal combustion engine 1 of the embodiment, air is supplied to the low pressure chamber 314, causing the piston 312 to slide, thereby further compressing the compressed air in the high pressure chamber 311 and injecting it into the combustion chamber 22. However, the internal combustion engine 1 may further compress the compressed air in the high pressure chamber 311 by another method and inject it into the combustion chamber 22. For example, the internal combustion engine 1 may inject the compressed air in the high pressure chamber 311 into the combustion chamber 22 by sliding the piston 312 with a solenoid actuator or a motor.

[0048] (Variation 3) The supply control unit 722 in the above embodiment injects compressed air into the combustion chamber 22 when it is determined that fuel has been injected into the combustion chamber 22 during the compression stroke. However, this is not limited thereto, and the supply control unit 722 may inject compressed air into the combustion chamber 22 in synchronization with the fuel injection timing of the fuel injection unit 26. For example, the acquisition unit 721 acquires a signal indicating the injection of the fuel 4 from a control unit (not shown) that controls the fuel injection unit 26, and the supply control unit 722 injects compressed air when the acquisition unit 721 acquires the signal indicating the injection. This makes it possible for the supply control unit 722 to inject the compressed air in the high pressure chamber 311 into the combustion chamber 22 in synchronization with the injection of the fuel 4.

[0049] [Effect of internal combustion engine 1] As described above, the internal combustion engine 1 includes the fuel injection unit 26 provided in the cylinder head 21 and injecting fuel into the combustion chamber 22, the high pressure chamber 311 to which the compressed air of the combustion chamber 22 is supplied during the compression stroke and capable of further compressing the compressed air, and the air injection unit 31 provided around the fuel injection unit 26 in the cylinder head 21 and injecting the compressed air compressed in the high pressure chamber 311 when the fuel injection unit 26 injects fuel. With the above configuration, the internal combustion engine 1 can inject compressed air into the space near the cylinder head 21 in the combustion chamber 22, which is narrower than the space near the piston 23 of the internal combustion engine 1. This allows the internal combustion engine 1 to supply air to the space near the cylinder head 21, which has a smaller amount of air than the space near the piston 23. As a result, the internal combustion engine 1 can supply sufficient air to the fuel injected into the space near the cylinder head 21, and can appropriately mix the fuel and the compressed air.

[0050] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination combines the effect of the original embodiment. [Explanation of symbols]

[0051] 1. Internal combustion engine 11 Intake pipe 12 Exhaust pipe 2 Cylinder 3 Air Injector 21 Cylinder head 21a Bottom side 22 Combustion chamber 23 Piston 24 Intake valve 25 Exhaust valve 26 Fuel injection section 31 Air injection section 311 Hyperbaric Chamber 312 Piston 312a Compression section 312b Pressure receiving part 313 Injection Nozzle 314 Low Pressure Room 315 Pump 316 Air supply pipe 7 Injection control device 71 Memory section 72 Control section 721 Acquisition Department 722 Supply control section

Claims

1. a fuel injection unit provided in the cylinder head and configured to inject fuel into the combustion chamber; a high-pressure chamber to which the compressed air from the combustion chamber is supplied during a compression stroke and capable of further compressing the compressed air; an air injection part that is provided around the fuel injection part in the cylinder head and that injects the compressed air compressed in the high-pressure chamber when the fuel injection part injects the fuel; An internal combustion engine having

2. The air injection unit is A piston is provided slidably within the high pressure chamber, When the fuel injection unit injects the fuel, the piston is caused to slide to further compress the compressed air in the high-pressure chamber, and the compressed air is injected into the combustion chamber.

2. The internal combustion engine of claim 1.

3. a low pressure chamber provided on the opposite side of the high pressure chamber across the piston; a supply control unit that supplies air to the low pressure chamber to slide the piston when the fuel injection unit injects the fuel.

3. The internal combustion engine according to claim 2.

4. The piston is a compression section accommodated in the high-pressure chamber and capable of compressing the compressed air; A pressure receiving portion connected to the compression portion, an area of ​​a first surface where the pressure receiving portion receives the pressure of the air in the low pressure chamber is larger than an area of ​​a second surface where the compression portion pressurizes the compressed air in the high pressure chamber; 4. An internal combustion engine according to claim 3.

5. The supply control unit removes the air in the low pressure chamber during an intake stroke immediately after injecting the compressed air.

5. An internal combustion engine according to claim 3 or 4.

6. When the compressed air compressed in the combustion chamber is supplied to the high-pressure chamber after the intake stroke is followed by the compression stroke, the piston slides so as to increase the volume of the high-pressure chamber.

6. An internal combustion engine according to claim 5.

7. the air injection unit communicates between the high-pressure chamber and the combustion chamber, and injects the compressed air from an injection nozzle provided at an angle with respect to a lower surface of the cylinder head toward a gap between the fuel injected into the combustion chamber and the cylinder head.

2. The internal combustion engine of claim 1.

8. A method for controlling an internal combustion engine having a cylinder head and a combustion chamber, comprising the steps of: supplying the compressed air compressed in the combustion chamber to a high pressure chamber capable of further compressing the compressed air during a compression stroke; a fuel injection unit provided in the cylinder head injecting fuel into the combustion chamber; an air injection unit provided around the fuel injection unit in the cylinder head injects compressed air compressed in the high-pressure chamber into the combustion chamber when the fuel injection unit injects the fuel; A method for controlling an internal combustion engine comprising the steps of:

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