JP2016217202A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of an excessive fuel area in a combustion engine, thereby to suppress generation of soot or the like, in an opposed piston type engine.SOLUTION: An internal combustion engine includes: a first cylinder part 10A that includes a first hole 11A through which a first piston 12A reciprocatively moves, and a recess 13A enlarged in an outer peripheral direction with respect to the first hole 11A over the whole circumference; a second cylinder part 10B that includes a second hole 11B through which a second piston 12B reciprocatively moves, and a second recess 13B enlarged in the outer peripheral direction with respect to the second hole 11B over the whole circumference, and that is oppositely arranged at a position where the pistons 12A, 12B are made close to each other at the position of an upper dead point; a combustion chamber X that is formed by the first piston 12A, the second piston 12B, the first recess 13A and the second recess 13B, and includes an enlarged portion X2 corresponding to the first recess 13A and the second recess 13B; and intake valves 33A, 33B and exhaust valve 34A, 34B that are opened/closed at the enlarged portion X2.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an opposed piston type internal combustion engine in which a first piston and a second piston are opposed to each other at a top dead center.

  There is known an opposed piston type internal combustion engine in which a first piston and a second piston are opposed to each other at a top dead center. For example, Patent Document 1 discloses a four-cycle engine in which a pair of pistons are arranged to face each other. In this engine, the combustion chamber is locally expanded to the outer peripheral side of the outer peripheral edge of each piston at the connecting position of the cylinder of the first piston and the cylinder of the second piston.

JP 2007-46534 A

  In the internal combustion engine of Patent Document 1 described above, the method for introducing fuel into the combustion chamber is not disclosed, but since it is understood that most of the combustion chamber is substantially the same as the diameter of the piston, depending on the method for introducing fuel, An excess fuel region is created in the combustion chamber. When this excess fuel region increases, soot, carbon monoxide, and unburned fuel are generated.

  It is an object of the disclosed internal combustion engine to suppress generation of excess fuel region in a combustion chamber and suppress generation of soot and the like.

  The disclosed internal combustion engine is in communication with a first piston, a first hole part in which the first piston is reciprocated, and a top dead center side end part of the first piston in the first hole part. A first cylinder portion having a first recess having a shape that is expanded in the outer circumferential direction from the first hole portion, a second piston, a second hole portion in which the second piston is reciprocated, and The second hole is provided with a second recess that communicates with the top dead center side end of the second piston in the second hole and is expanded in the outer circumferential direction from the second hole over the entire circumference. Formed by a second cylinder portion disposed opposite to the position at which the second piston and the first piston are close to each other, the first piston, the second piston, the first recess, and the second recess. And an enlarged portion corresponding to the first recess and the second recess. Comprising a combustion chamber, and a intake valve and an exhaust valve are opened and closed by the enlarged portion of said combustion chamber.

  According to the disclosed internal combustion engine, generation of excess fuel region in the combustion chamber can be suppressed, and generation of soot and the like can be suppressed.

It is a typical sectional view of an engine. (A) is a figure which illustrates typically the combustion chamber periphery in the 1st cylinder part of 1st Embodiment, (B) is a figure which illustrates the combustion chamber periphery in a 2nd cylinder part typically. It is a typical fragmentary expanded sectional view explaining the combustion injection to a combustion chamber. It is a typical partial expanded sectional view in the engine of a 2nd embodiment. It is a typical partial expanded sectional view in the engine of a 3rd embodiment. (A) is a figure which illustrates typically the combustion chamber periphery in the 1st cylinder part of 3rd Embodiment, (B) is a figure which illustrates typically the combustion chamber periphery in a 2nd cylinder part.

  Hereinafter, a diesel engine (an example of an internal combustion engine, hereinafter simply referred to as an engine) according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  An engine 100 shown in FIG. 1 is an opposed piston type engine including a first engine unit 1A and a second engine unit 1B. The first engine unit 1A and the second engine unit 1B reciprocate on the same axis so that the first piston 12A and the second piston 12B are close to each other at the top dead center position. It is attached to do.

  First, the 1st engine unit 1A located in the left half part in Drawing 1 is explained.

  The first engine unit 1A includes a first cylinder portion 10A. The first cylinder portion 10A is formed with a circular first hole portion 11A in which the first piston 12A is housed so as to be reciprocally movable. In the present embodiment, since the first piston 12A is moved in the horizontal direction, the first hole portion 11A is formed by a hole extending in the horizontal direction.

  As shown in FIG. 2A, a first recess 13A is formed at the top dead center side end (one end) of the first hole portion 11A so as to communicate with the first hole portion 11A. The first hole 13A forms a combustion chamber X together with the first piston 12A and the second piston 12B and the second recess 13B (described later) provided in the second engine unit 1B. The first recess 13A will be described later together with the combustion chamber X.

  As shown in FIG. 1, the bottom dead center side end (the other end) of the first hole portion 11A is connected to the first crankcase portion 20A. In the first crankcase portion 20A, the first crankshaft 21A is disposed in a rotatable state. The other end of the first connecting rod 23A is attached to the first crank pin 22A included in the first crankshaft 21A in a rotatable state. One end of the first connecting rod 23A is attached to a piston pin 12b included in the first piston 12A in a rotatable state.

  A first oil jet 25A for injecting oil supplied from the first oil passage 24A toward the combustion chamber X side is provided at the boundary between the first crankcase portion 20A and the first cylinder portion 10A. The oil injected from the first oil jet 25A flows into a cooling channel (not shown) formed inside the first piston 12A, and is used for cooling the first piston 12A.

  Further, a first intake port 31A and a first exhaust port 32A are formed in the first cylinder portion 10A. The first intake port 31A is a flow path for introducing fresh air, and the first exhaust port 32A is a flow path for discharging exhaust gas. As shown in FIG. 2A, the outlet of the first intake port 31A is opened to the combustion chamber X (the bottom surface 13a of the first recess 13A), and the inlet of the first exhaust port 32A is the combustion chamber X. Is opened at a position on the opposite side across the hole 11A.

  A first intake valve 33A is disposed at the first intake port 31A, and a first exhaust valve 34A is disposed at the first exhaust port 32A. Specifically, the umbrella portion of the first intake valve 33A is disposed at the outlet of the first intake port 31A, and the umbrella portion of the first exhaust valve 34A is disposed at the inlet of the first exhaust port 32A.

  As shown in FIG. 1, a force in a direction away from the combustion chamber X is applied to the first intake valve 33A and the first exhaust valve 34A by a first valve spring 35A provided at each shaft portion. In addition, first hydraulic plungers 36A are disposed at the tips of the first intake valve 33A and the first exhaust valve 34A (ends opposite to the umbrella portions), respectively.

  The first hydraulic plunger 36A includes a pin 36a that is moved in the vertical direction according to the hydraulic pressure, and the tip end surface of the pin 36a is in contact with the tip end surface of each of the valves 33A and 34A. When the pin 36a is moved in the direction of the combustion chamber X against the restoring force of the first valve spring 35A due to an increase in hydraulic pressure, the corresponding second intake valve 33A and first exhaust valve 34A are lifted in the valve opening direction. To do. On the other hand, when the restoring force of the first valve spring 35A wins due to the decrease in hydraulic pressure, the pin 36a is moved away from the combustion chamber X, and the corresponding first intake valve 33A and first exhaust valve 34A are moved in the valve closing direction. Moving.

  The first hydraulic plunger 36A is electrically connected to an electronic control unit (hereinafter referred to as ECU 50), and the operation (movement amount of the pin 36a) is controlled in accordance with a control signal from the ECU 50. For example, the operation of the first hydraulic plunger 36A is controlled in conjunction with the reciprocating movement of the first piston 12A. Therefore, the set of the first hydraulic plunger 36A and the ECU 50 is an example of an intake valve control unit and an exhaust valve control unit.

  A first injector 41A is arranged at a position on the first intake valve 33A side in the combustion chamber X. The first injector 41A is a member that injects fuel into the combustion chamber X. As shown in FIG. 2 (A), a pair of injection holes 42A are formed at the tip portion disposed in the combustion chamber X. The fuel is injected into the entire combustion chamber X along the bottom surfaces 13a of the recesses 13A and 13B and the top surfaces 12a of the pistons 12A and 12B (see FIGS. 2A and 2B).

  Next, the 2nd engine unit 1B located in the right half part in FIG. 2 is demonstrated. Since the configuration of the second engine unit 1B is the same as that of the first engine unit 1A, the main points will be described here.

  The second engine unit 1B includes a second cylinder part 10B. The second cylinder part 10B is formed with a circular second hole part 11B in which the second piston 12B is accommodated in a reciprocable manner. The second hole portion 11B has the same shape (the same diameter and the same length) as the first hole portion 11A, and is formed coaxially with the first hole portion 11A.

  The second piston 12B has the same shape as the first piston 12A, and operates in line symmetry with the first piston 12A across the combustion chamber X. For example, when the first piston 12A is moving to the top dead center side (combustion chamber X side), the second piston 12B is also moving to the top dead center side (combustion chamber X side). On the other hand, when the first piston 12A is moving to the bottom dead center side (the first crankcase part 20A side), the second piston 12B is also the top dead center side (the second crankcase part 20B provided in the second engine unit 1B). Side).

  As shown in FIG. 2B, a second recessed portion 13B is formed at the top dead center side end (one end) of the second hole portion 11B so as to communicate with the second hole portion 112B. The second recess 13B will be described later together with the first recess 13A and the combustion chamber X.

  As shown in FIG. 1, the bottom dead center side end (the other end) of the second hole portion 11B is connected to the second crankcase portion 20B. In the second crankcase portion 20B, the second crankshaft 21B is disposed in a rotatable state. One end of the second connecting rod 23B is rotatably attached to the piston pin 12b included in the second piston 12B, and the other end of the second connecting rod 23B is attached to the second crank pin 22B in a rotatable state. .

  A second oil passage 24B and a second oil jet 25B are provided at the boundary between the second crankcase portion 20B and the second cylinder portion 10B. The oil injected from the second oil jet 25B is used for cooling the second piston 12B.

  Further, a second intake port 31B and a second exhaust port 32B are formed in the second cylinder portion 10B. As shown in FIG. 2B, the outlet of the second intake port 31B is open to the combustion chamber X (the bottom surface 13a of the second recess 13B), and the inlet of the second exhaust port 32B is the combustion chamber X. Is opened at a position on the opposite side across the hole 11B. A second intake valve 33B is disposed at the second intake port 31B, and a second exhaust valve 34B is disposed at the second exhaust port 32B.

  As shown in FIG. 1, a force in a direction away from the combustion chamber X is applied to the second intake valve 33 </ b> B and the second exhaust valve 34 </ b> B by a second valve spring 35 </ b> B provided at each shaft portion. Further, second hydraulic plungers 36B are disposed at the tips of the second intake valve 33B and the second exhaust valve 34B, respectively.

  The second hydraulic plunger 36B includes a pin 36a that is moved in the vertical direction in accordance with the hydraulic pressure, and the tip end surface of the pin 36a is in contact with the tip end surface of each of the valves 33B and 34B. The pin 36a moves to the combustion chamber X side with a stronger force as the hydraulic pressure increases. The movement amount (valve lift amount) of the second intake valve 33B and the second exhaust valve 34B in the valve opening direction and the valve closing direction is determined by the balance with the restoring force of the second valve spring 35B.

  The second hydraulic plunger 36B is also electrically connected to the ECU 50, and the operation (the amount of movement of the pin 36a) is controlled in accordance with a control signal from the ECU 50. For example, the operation of the second hydraulic plunger 36B is controlled in conjunction with the reciprocating movement of the second piston 12B. Therefore, the set of the second hydraulic plunger 36B and the ECU 50 is an example of an intake valve control unit and an exhaust valve control unit.

  A second injector 41B is disposed at a position on the second exhaust valve 34B side in the combustion chamber X. The second injector 41B is a member that injects fuel into the combustion chamber X. As shown in FIG. 2 (B), a pair of injection holes 42B are formed at the tip portion disposed in the combustion chamber X. The fuel is injected into the entire combustion chamber X along the bottom surfaces 13a of the recesses 13A and 13B and the top surfaces 12a of the pistons 12A and 12B (see FIGS. 2A and 2B).

Next, the combustion chamber X will be described in detail. As shown in FIGS. 2A and 2B, the combustion chamber X includes a first recess 13A, a second recess 13B, a first piston 12A, and a second piston 12B.
Is formed by. The volume of the combustion chamber X is the same as the volume of a general combustion chamber formed at the upper end portion of the first hole portion 11A or the second hole portion 11B without including the concave portions 13A and 13B. In other words, the combustion chamber X of this embodiment and the general combustion chamber have the same compression ratio.

  As shown in FIG. 2 (A), the first recess 13A has an outer peripheral direction (radial direction of the first hole 11A) over the entire periphery rather than the edge of the first hole 11A in which the first piston 12A reciprocates. And is formed by a bottom surface 13a and side surfaces (circumferential surfaces) 13b.

  The bottom surface 13a of the first recess 13A is provided in a circular ring shape centered on the first hole portion 11A when viewed from the plane direction. In the illustrated example, the bottom surface 13a is formed by an inclined surface that descends from the inner periphery to the outer periphery. As shown in FIG. 1, in this embodiment, since the top surface 12a of the first piston 12A is formed in a conical shape with a low height, the bottom surface 13a of the first recess 13A is also the top surface 12a of the first piston 12A. The inclined surface has the same inclination angle. Thus, when the first piston 12 is located at the top dead center, the top surface 12a of the piston 12 and the bottom surface 13a of the recess 13 form a series of inclined surfaces (conical surfaces). Further, the side surface 13b of the first recess 13A is configured by a surface that rises from the outer peripheral edge of the bottom surface 13a toward the second engine unit 1B.

  As shown in FIG. 2B, the second recess 13B has an outer peripheral direction (radial direction of the second hole 11B) over the entire periphery rather than the edge of the second hole 11B in which the second piston 12B reciprocates. Like the first recess 13A, the shape is formed by the bottom surface 13a and the side surface 13b.

  As shown in FIGS. 2 (A) and 2 (B), in this combustion chamber X, the opposed portions of the pistons 12A, 12B (the top surfaces 12a) are the center side portions X1, and the outer periphery of the center side portion X1. A portion located in the direction and located above each bottom surface 13a of each recess 13A, 13B is an enlarged portion X2. In the present embodiment, two intake valves 33A and 33B and two exhaust valves 34A and 34B are arranged in the enlarged portion X2. The width of each bottom surface 13a (the length in the radial direction of each hole 11A, 11B) is equal to or greater than the diameter of the umbrella portion of each intake valve 33A, 33B and the umbrella portion of each exhaust valve 34A, 34B. Therefore, the intake / exhaust valves 33A, 33B, 34A, 34B can be opened and closed regardless of the positions of the pistons 12A, 12B.

  As shown in FIG. 2, the combustion chamber X is expanded in the outer peripheral direction from the hole portions 11A and 11B by the concave portions 13A and 13B expanded in the outer peripheral direction from the hole portions 11A and 11B. As shown in FIG. 3, the fuel F injected from the first injection hole 42A of the first injector 41A by the enlarged combustion chamber X is the same as the fuel F injected from the second injection hole 42B of the second injector 41B. A sufficiently long distance until the collision can be secured. Thereby, the fuel F can be sufficiently diffused in the combustion chamber X. In addition, the amount of fuel F that directly collides with the side surface 13b of the recess 13 can be suppressed. As a result, it becomes easy to uniformly mix the fuel F and air, and the generation of an excessive fuel region can be suppressed.

  As described above, in the engine 100 according to the first embodiment, the first hole 11A in which the first piston 12A is reciprocated and the top dead center side end of the first piston 12A in the first hole 11A. A first cylinder portion 10A including a circular ring-shaped first concave portion 13A which is communicated and expanded in the outer peripheral direction (radial direction of the first hole portion 11A) from the first hole portion 11A over the entire circumference; The second hole portion 11B in which the piston 12B is reciprocated and the top dead center side end portion of the second piston 12B in the second hole portion 11B are communicated to the outer peripheral direction of the second hole portion 12B over the entire circumference. A second recess 13B having an enlarged shape (in the radial direction of the second hole portion 11B) is provided, and the second piston 12B and the first piston 12A are opposed to each other at a position close to the top dead center. Cylinder portion 10B and first piston 2A, the second piston 12B, the first recess 13A, and the second recess 13B. The combustion chamber X includes an enlarged portion X2 corresponding to the first recess 13A and the second recess 13B, and the enlarged portion X2 of the combustion chamber X. Are provided with a pair of intake valves 33A, 33B and a pair of exhaust valves 34A, 34B.

  Thus, since the combustion chamber X is provided with the expansion part X2, the freedom degree with respect to the shape of the combustion chamber X can be raised. Thereby, the fuel F injected from the injection holes 42A and 42B included in the injectors 41A and 41B can be sufficiently diffused in the combustion chamber X. As a result, the fuel concentration in the combustion chamber X can be equalized, and the production of soot, carbon monoxide, and unburned fuel can be suppressed. In addition, since the combustion chamber X can be made shallower than the combustion chamber having a general shape and expands in the plane direction, it becomes difficult for the flame to come into contact with the fuel F being diffused, and the fuel F can be burned efficiently. it can.

  Further, in the engine 100 of the present embodiment, since the intake valves 33A, 33B and the exhaust valves 34A, 34B are arranged in the enlarged portion X2 of the combustion chamber X, the lift amount of the valves 33A, 33B, 34A, 34B. Can be determined regardless of the positions of the pistons 12A and 12B, and the degree of freedom in controlling the in-cylinder air amount can be increased. Thereby, an in-cylinder pressure can be adjusted and the gas flow in a cylinder can be adjusted. As a result, it is possible to increase the degree of freedom for various controls such as the strength of the compression release brake and the intake air amount.

  In addition, since the opening / closing operations of the valves 33A, 33B, 34A, and 34B are controlled by the hydraulic plungers 36A and 36B and the ECU 50, the valve lift amount and the lift timing can be accurately controlled. In this respect also, the degree of freedom for controlling the in-cylinder air amount can be increased.

  Next, the engine 1 which concerns on 2nd Embodiment of this invention is demonstrated. The engine 100 of the second embodiment is different from the first embodiment in that the arrangement of the first injector 41A and the second injector 41B, and the first spark plug 43A and the second spark plug 43B are provided. Since other parts are common to the first embodiment, the parts relating to the differences will be described below, and the description of the common parts will be omitted.

  As shown in FIG. 4, in the engine 100 of the second embodiment, the tip of the first injector 41A faces the first intake port 31A, and the tip of the second injector 41B faces the second intake port 31B. The injectors 41A and 41B inject fuel at the intake timing at which the intake valves 33A and 33B are opened. Further, the electrodes of the first spark plug 43A and the second spark plug 43B face the combustion chamber X. As a result, an air-fuel mixture in which fresh air and fuel are mixed is introduced into the combustion chamber X through the intake ports 31A and 31B. And it is ignited by each spark plug 43A, 43B.

  Also in this engine 100, since the combustion chamber X includes the center portion X1 and the enlarged portion X2, the degree of freedom with respect to the shape of the combustion chamber X can be increased. Thereby, the fuel F injected from the injection holes 42A and 42B included in the injectors 41A and 41B can be sufficiently diffused in the combustion chamber X. As a result, the fuel concentration in the combustion chamber X can be equalized, and the production of soot, carbon monoxide, and unburned fuel can be suppressed. In addition, since the combustion chamber X can be made shallower than the combustion chamber having a general shape and expands in the plane direction, it becomes difficult for the flame to come into contact with the fuel F being diffused, and the fuel F can be burned efficiently. it can. Note that the number of spark plugs is not limited to two, and it is sufficient that at least one spark plug is provided.

  Next, an engine 100 according to a third embodiment of the present invention will be described. In the engine 100 of the third embodiment, the shape of each top surface 12a of each piston 12A, 12B is different from each top surface 12a of the first embodiment. For this reason, below, the part regarding a difference is demonstrated and the description about a common part is abbreviate | omitted.

  As shown in FIGS. 5 and 6, the combustion chamber X of the third embodiment is also formed by the recesses 13A and 13B and the pistons 12A and 12B. That is, each of the recesses 13A and 13B is formed by a bottom surface 13a and a side surface 13b, and the combustion chamber X includes a center side portion X1 and an enlarged portion X2 that is enlarged in the outer peripheral direction with respect to the center side portion X1. In the second embodiment, the volume of the combustion chamber X is the same as the volume of a general combustion chamber.

  As shown in FIG. 5, each top surface 12a of each piston 12A, 12B is configured by a curved concave surface that is recessed like a concave mirror. Following the curved concave surface of each top surface 12a, each bottom surface 13a of each concave portion 13A, 13B is also formed by an inclined surface inclined downward from the outer peripheral edge toward the inner peripheral edge.

  Further, as shown in FIGS. 6A and 6B, the recesses 13A and 13B are elliptical when viewed from the moving direction of the pistons 12A and 12B. Specifically, regarding the shape of the combustion chamber X, the shape of the combustion chamber X is an ellipse with a narrow width at the position of each injection hole 42A, 42B and a wide width at the center position of each top surface 12a.

  That is, the combustion chamber X of the present embodiment has a shape that is gradually enlarged from the position of each injection hole 42A, 42B toward the center position of each top surface 12a. Thereby, even if the fuel F injected from each injection hole 42A, 42B spreads far enough to fly far away, it directly collides with each bottom surface 13a of each recess 13A, 13B and each top surface 12a of each piston 12A, 12B. The amount of fuel F to be reduced can be reduced. As a result, it becomes easy to uniformly mix the fuel F and air, and the generation of an excessive fuel region can be suppressed. Therefore, in the engine 100 of the second embodiment, the fuel concentration in the combustion chamber X can be equalized, and the generation of soot, carbon monoxide, and unburned fuel can be further suppressed.

  The above description of the embodiment is for facilitating the understanding of the present invention, and does not limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  For example, in each of the above-described embodiments, two intake valves and two exhaust valves are provided, but the number is not limited thereto. One intake valve and one exhaust valve may be provided, or three or more intake valves may be provided.

  In each of the above-described embodiments, the intake valve and the exhaust valve are operated by the hydraulic actuator, but may be operated by the cam and the rocker arm.

DESCRIPTION OF SYMBOLS 100 ... Diesel engine, 1A ... 1st engine unit, 1B ... 1st engine unit, 10A ... 1st cylinder part, 10B ... 2nd cylinder part, 11A ... 1st hole part, 11B ... 2nd hole part, 12A ... 1st 1 piston, 12B ... second piston, 12a ... top surface of piston, 12b ... piston pin, 13A ... first recess, 13B ... second recess, 13a ... bottom surface of recess, 13b ... side surface of recess, 20A ... first crank Case part, 20B ... 2nd crankcase part, 21A ... 1st crankshaft, 21B ... 2nd crankshaft, 22A ... 1st crankpin, 22B ... 2nd crankpin, 23A ... 1st connecting rod, 23B ... 2nd connecting rod , 24A ... first oil passage, 24B ... second oil passage, 25A ... first oil jet, 25B ... second oil jet, 31A ... 1 intake port, 31B ... 2nd intake port, 32A ... 1st exhaust port, 32B ... 2nd exhaust port, 33A ... 1st intake valve, 33B ... 2nd intake valve, 34A ... 1st exhaust valve, 34B ... 2nd Exhaust valve, 35A ... first valve spring, 35B ... second valve spring, 36A ... first hydraulic plunger, 36B ... second hydraulic plunger, 36a ... pin, 41A ... first injector, 41B ... second injector, 42A ... first 1 injection hole, 42B ... 2nd injection hole, 43A ... 1st spark plug, 43B ... 2nd spark plug, X ... combustion chamber, X1 ... center side part of combustion chamber, X2 ... expansion part of combustion chamber, F ... fuel

Claims (5)

A first piston;
A first hole part in which the first piston is reciprocated and a top dead center side end part of the first piston in the first hole part, and the outer periphery of the first hole part over the entire circumference. A first cylinder portion including a first recess having a shape expanded in a direction;
A second piston;
A second hole part where the second piston is reciprocated and a top dead center side end part of the second piston in the second hole part, and the outer periphery of the second hole part over the entire circumference. A second cylinder portion that is provided with a second recess having a shape enlarged in a direction, and that is opposed to a position where the second piston and the first piston are close to each other at a top dead center position;
A combustion chamber formed by the first piston, the second piston, the first recess, and the second recess, and having an enlarged portion corresponding to the first recess and the second recess;
An internal combustion engine comprising: an intake valve and an exhaust valve that are opened and closed at the enlarged portion of the combustion chamber. An intake port in which air is introduced into the combustion chamber and the intake valve is disposed at an outlet;
An exhaust port for exhausting the exhaust from the combustion chamber, wherein the exhaust valve is disposed at the inlet;
The internal combustion engine according to claim 1, further comprising: an injector in which an injection hole faces the intake port and injects fuel from the intake port into the combustion chamber. A plurality of the intake valves are provided for one piston,
The internal combustion engine according to claim 1, further comprising intake valve control means for individually controlling opening and closing operations of the plurality of intake valves. A plurality of the exhaust valves are provided for one piston,
The internal combustion engine according to any one of claims 1 to 3, further comprising exhaust valve control means for individually controlling opening and closing operations of the plurality of exhaust valves. An injector for injecting fuel from the side of the combustion chamber along the top surface of the piston;
The internal combustion engine according to claim 1, wherein the recess has a shape in which the width of the other side portion in the combustion chamber is wider than the width of the one side portion.

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