JP6657629B2 - engine - Google Patents

Description

  The present invention relates to an engine provided with an EGR system for introducing a part of exhaust gas into an intake system.

  2. Description of the Related Art Conventionally, an EGR (Exhaust Gas Recirculation) system that improves fuel efficiency and environmental performance by recirculating exhaust gas of an engine mounted on a vehicle from an exhaust system to an intake system has been known. That is, the exhaust passage and the intake passage are connected by an EGR passage, and part of the exhaust gas is introduced into the cylinder again as EGR gas. In recent years, in such an EGR system, a system in which an outlet of an EGR passage is set to an intake port has been developed. By supplying EGR gas to the intake air flow just before being taken into the cylinder, the fresh air and fuel mixture and the EGR gas are more likely to be introduced into the cylinder while being separated in layers, and the combustion state in the cylinder Can be stabilized (see Patent Document 1).

JP 2009-121366 A

  However, since pressure pulsation occurs due to opening and closing of the intake valve in the intake port, it is difficult to sufficiently separate EGR gas and fuel depending on the timing of fuel injection and the timing of introduction of EGR gas. . For example, when the fuel injection is performed in the exhaust stroke in which the intake valve is closed, the vaporized fuel stays in the intake port. Thereafter, when the intake valve is opened in the intake stroke, the pressure in the intake port decreases, and fresh air and EGR gas flow into the intake port.

  At this time, the vaporized fuel and the EGR gas remaining in the intake port are introduced into the cylinder while being mixed. As a result, it is difficult to form a stratified state of the mixture of the fuel and the fresh air and the EGR gas, and the combustion state in the cylinder may become unstable. On the other hand, even if fuel is injected during the intake stroke, fresh air flows into the intake port later than the EGR gas, so it is difficult to avoid mixing fuel spray and EGR gas. Note that such a problem may also occur when air (fresh air) is injected into the intake port instead of the EGR gas.

  One of the objects of the present invention has been made in view of the above-described problems, and it is an object of the present invention to provide an engine having an improved combustion state in a cylinder. It is to be noted that the present invention is not limited to this object, and is an operation and effect derived from each configuration shown in “Embodiments for carrying out the invention” described later, and it is possible to obtain an operation and effect that cannot be obtained by the conventional technology. Can be positioned as an objective.

(1) Engine disclosed herein, an intake valve for opening and closing the opening of the cylinder side of the intake port, and a gas injection port for injecting a gas toward the opening in the intake port, from the gas injection port A fuel injection port which is provided upstream and injects fuel into the intake port during an intake stroke. In the intake stroke, fuel injection from the fuel injection port is stopped at least until the intake valve is opened, and the fuel injection is started after the intake valve in which the gas flows into the cylinder is opened. A control device for causing the The gas injection port injects the gas toward the stem of the intake valve, and the fuel injection port is in a direction along an injection direction of the gas injected from the gas injection port, and is configured to inject the gas. The fuel is injected in a direction parallel to the direction.

(2) The control device may stop fuel injection from the fuel injection port until a predetermined time has elapsed since the opening of the intake valve, and may start the fuel injection after the predetermined time has elapsed. preferable. Further, even after a predetermined time has elapsed since the opening of the intake valve, if the piston is rising (before top dead center), burned gas (exhaust gas) in the combustion chamber is supplied to the intake port. It is preferable to start the fuel injection after the piston starts descending (after the top dead center) because the fuel flows backward.
(3) It is preferable that the control device sets the predetermined time based on an opening acceleration of the intake valve.

(4) It is preferable that the control device sets, as the predetermined time, a time until the opening acceleration of the intake valve changes from positive to negative during the intake stroke.
(5) It is preferable that the control device increases the pressure of the fuel as the engine speed or the engine load increases.

( 7 ) Preferably, the gas injected from the gas injection port is a part of the exhaust gas of the engine. That is, it is preferable that the gas injection port is an exhaust gas recirculation port that injects a part of the exhaust gas into the intake port. The exhaust gas recirculation port may be an end opening of an exhaust gas recirculation passage for introducing a part of the exhaust gas into the intake port without pressurizing the exhaust gas. Alternatively, an end opening of an exhaust injection passage that pressurizes a part of the exhaust gas and introduces it into the intake port may be used.

  According to the disclosed engine, the mixture of fuel (or a mixture of fuel and air) and the gas (eg, EGR gas) injected from the gas injection port is suppressed while suppressing the adhesion of the fuel to the intake valve. be able to. Therefore, the combustion state in the cylinder can be improved.

It is a typical sectional view showing the structure of the engine as an embodiment. It is a cylinder top view of an engine. It is a perspective view which shows the distribution state of an exhaust flow typically. (A) is a graph which shows a valve lift, (B) is a graph which shows valve opening acceleration. FIG. 2 is a schematic cross-sectional view of an engine (early in an intake stroke). FIG. 2 is a schematic sectional view of an engine (during fuel injection). FIG. 3 is a schematic sectional view of an engine (middle stage of an intake stroke). It is a typical sectional view showing the structure of the engine as a modification. It is a typical sectional view showing the structure of the engine as a modification.

  An engine as an embodiment will be described with reference to the drawings. Note that the embodiments described below are merely examples, and there is no intention to exclude various modifications and application of technology not explicitly described in the following embodiments. Each configuration of the present embodiment can be variously modified and implemented without departing from the spirit thereof. Further, they can be selected as needed, or can be appropriately combined. In the following description, it is assumed that the vertical direction of each part is determined based on a state in which the engine is arranged such that the center axis of the cylinder is vertical (a state in which the intake port and the exhaust port are located above).

[1. Constitution]
[1-1. engine]
FIG. 1 shows an engine 20 of the present embodiment. The engine 20 is a gasoline engine provided with an EGR system (exhaust gas recirculation system) for circulating a part of the exhaust gas into the intake port 1 of the cylinder head 21. The top surface of the cylinder 23 of the engine 20 is a pent roof type (gable roof type) in which an inclined surface to which the intake port 1 is connected and an inclined surface to which the exhaust port 3 is connected are joined in a triangular roof shape. On this top surface, an intake valve 10 is provided in the opening 2 connected to the intake port 1, and an exhaust valve 15 is provided in the opening 4 connected to the exhaust port 3. Each of these openings 2, 4, intake valve 10, and exhaust valve 15 is provided two each. As shown in FIG. 2, the intake port 1 has a siamese shape in which one passage is branched toward two openings 2. Similarly, the exhaust port 3 also has a siamese shape in which the passages connected to the two openings 4 merge into one. Further, with respect to the intake, one opening 2 and one intake valve 10 may be provided with respect to the cylinder 23, and the intake port 1 and the exhaust port 3 may not have a siamese shape.

  The intake port 1 is connected to an exhaust return passage 5 which is one of EGR passages, and is provided with an injector 7. Here, the end opening of the exhaust return passage 5 that is open toward the intake port 1 is referred to as an exhaust gas recirculation port 6. Further, the injection hole of the injector 7 is called a fuel injection port 8. The upstream side of the exhaust return passage 5 is connected to the exhaust passage of the engine 20. The upstream side of the injector 7 is connected to a fuel supply pipe.

[1-2. Exhaust gas recirculation port]
The exhaust gas recirculation port 6 (gas injection port) injects gas into the intake port 1. For example, the exhaust gas that has passed through the exhaust return passage 5 is injected into the intake port 1 as an exhaust flow toward the opening 2. With the ability to The exhaust gas recirculation port 6 of the present embodiment is an end opening of an EGR passage for introducing a part of exhaust gas into the intake port 1 without pressurizing the exhaust gas. When an EGR system that pressurizes part of the exhaust gas and introduces it into the intake port 1 is provided, the end opening of the EGR passage through which the pressurized exhaust gas flows functions as the exhaust gas recirculation port 6. May be. Further, a gas other than the exhaust gas may be injected into the intake port 1.

  The shape of the exhaust stream injected from the exhaust gas recirculation port 6 is generally a cone or fan with a small divergence angle along the path from the exhaust gas recirculation port 6 to the opening 2. The flow rate of the exhaust flow injected from the exhaust gas recirculation port 6 varies according to the exhaust pressure and the intake pressure (the internal pressure of the intake port 1). When a flow control valve (EGR valve) or a pressure reducing device is provided in the exhaust return passage 5, the pressure varies according to the opening of the flow control valve and the pressure in the exhaust return passage 5.

  The position of the exhaust gas recirculation port 6 is set on the inner wall surface above the center line of the intake port 1 in the vertical section. That is, the exhaust gas recirculation port 6 is provided on the outer wall surface at the bent portion of the intake port 1. In the example shown in FIG. 1, the exhaust gas recirculation port 6 is provided near the wall surface of the intake port 1, but the exhaust return passage 5 is extended to the inside of the intake port 1, and is located at a position slightly away from the wall surface of the intake port 1. An exhaust gas recirculation port 6 may be provided. Further, as shown in FIG. 2, one exhaust recirculation port 6 is provided for each of the two openings 2 in each cylinder 23, or one for each of the two openings 2.

  The direction of injection of the exhaust flow is at least along the inner wall surface of the intake port 1. Preferably, as shown in FIG. 1, the exhaust flow is injected along the outer peripheral wall surface at the bent portion of the intake port 1. As a result, while the exhaust flow is being injected, the outer surface of the swirl outside of the intake port 1 is covered in a curtain shape by the exhaust flow, and the fuel injected from the injector 7 flows to the inner wall surface of the intake port 1. Adhesion is suppressed.

  In addition, as shown in FIG. 2, the injection direction of the exhaust flow when viewed from above the engine 20 is a direction substantially perpendicular to the ridgeline of the pent roof shape and a direction substantially toward the center of the opening 2. That is, the exhaust flow is injected toward the stem 11 of the intake valve 10. Therefore, the exhaust flow injected along the outer wall surface at the bent portion of the intake port 1 collides with the stem 11 of the intake valve 10 and flows along the umbrella back surface 13 of the intake valve 10. At this time, a part of the exhaust gas flows while diffusing in a direction away from the stem 11, as shown in FIG. The other part of the exhaust gas flows along the peripheral surface of the stem 11 to the downstream side thereof. These exhaust flows are introduced into the cylinder 23 through a gap between the head 12 of the intake valve 10 and the opening 2.

[1-3. Fuel injection port]
The fuel injection port 8 has a function of injecting fuel into the intake port 1 during an intake stroke of the engine 20. Fuel is injected into the intake port 1 where the exhaust flow is formed. The amount of fuel injected from the fuel injection port 8 varies depending on the pressure (fuel pressure) of the fuel supplied to the fuel injection port 8 and the valve opening time of the fuel injection port 8.
The position of the fuel injection port 8 is set on the inner wall surface on the upstream side of the exhaust gas recirculation port 6 and above the intake port 1 in a longitudinal section. The exhaust gas flow injected from the exhaust gas recirculation port 6 flows along the inner wall surface of the intake port 1 and becomes a laminar flow covering the surface thereof. On the other hand, the fuel is injected from an upstream side of the inner wall surface whose surface is covered by the exhaust flow. Thereby, the adhesion of the fuel to the inner wall surface of the intake port 1 is suppressed.

  The upstream side here means that the distance to the opening 2 is long with respect to the center line of the intake port 1. For example, as shown in FIG. 1, a perpendicular line is drawn from the exhaust gas recirculation port 6 to the center line of the intake port 1, and the foot of the perpendicular line is defined as a point A. On the other hand, a perpendicular is lowered from the fuel injection port 8 to the center line of the intake port 1, and the foot of the perpendicular is defined as a point B. Point B is located at a position farther from opening 2 than point A. Further, as shown in FIG. 2, the position of the fuel injection port 8 in the top view of the engine 20 is upstream of the position where the intake port 1 branches toward the two openings 2, and It is arranged almost in the center.

  As shown in FIG. 1, the fuel injection direction is a direction along the injection direction of the exhaust flow injected from the exhaust gas recirculation port 6. Here, the “direction along the exhaust flow injection direction” is a fuel injection direction whose angle with the exhaust flow distribution direction is within a range of approximately −45 ° to 45 °. The “direction along the exhaust stream injection direction” includes a direction parallel to the exhaust stream flow direction. Further, as shown in FIG. 2, the fuel injection directions of the engine 20 in a top view are set in two directions toward each of the two openings 2 toward the center of the opening 2. The fuel injection direction is set to intersect the exhaust flow injection direction on the upstream side of the head 12 of the intake valve 10. As a result, the fuel spray is supplied to each of the exhaust flow drawn into one opening 2 and the exhaust flow drawn into the other opening 2, and a mixture of fuel and air or a fuel spray is applied to the surface layer. The exhaust gas flow is introduced into the cylinder 23.

[1-4. Control device]
The control device 9 is an electronic control device that controls at least the fuel injection system of the engine 20, and is an electronic device in which processors such as a CPU and an MPU, ROM, RAM, and nonvolatile memory are integrated. The processor is an arithmetic processing device including a control circuit, an arithmetic circuit, a cache memory, and the like. The ROM, the RAM, and the nonvolatile memory are memory devices that store programs and data during work. The control content of the control device 9 is recorded as an application program in ROM, RAM, and nonvolatile memory. When the program is executed, the contents of the program are expanded in the memory space in the RAM and executed by the processor.

The control device 9 includes a cam angle sensor 31 that detects a rotation angle (cam rotation angle) of a cam shaft that drives the intake cam 25 and the exhaust cam 26, and detects a rotation angle (crank angle) of the crankshaft of the engine 20. The crank angle sensor 32 is connected. The control device 9 controls the fuel injection amount, the injection timing, and the fuel pressure of the injector 7 based on the cam rotation angle and the crank angle.
The fuel injection timing is set at least during the intake stroke of the engine 20 and while the intake valve 10 is open. Preferably, control is performed based on the opening acceleration of intake valve 10 during the intake stroke. Here, the fuel injection is performed within the intake stroke (after the exhaust top dead center) and at least after the intake valve 10 is opened. That is, fuel injection is performed in a state in which the exhaust gas flow injected from the exhaust gas recirculation port 6 is introduced into the cylinder 23 through the gap between the opened intake valve 10 and the intake port 1. Further, in the present embodiment, during the intake stroke of the engine 20 and at least after a predetermined time has elapsed since the opening of the intake valve 10 [in the section between θ ₂ and θ ₅ in FIG. Fuel injection is started. The predetermined time here is set based on the opening acceleration of the intake valve 10. For example, the time until the opening acceleration of the intake valve 10 changes from positive to negative during the intake stroke is set as the predetermined time. Even if a predetermined time has elapsed since the intake valve 10 was opened, if the piston is rising (before top dead center), the burned gas (exhaust gas) in the combustion chamber is discharged to the intake port 1. Therefore, it is preferable to start fuel injection after the piston starts to descend (after top dead center).

Each of the crank angles θ ₁ , θ ₃ , and θ ₅ in FIG. 4A corresponds to the opening time, the maximum opening time, and the closing time of the intake valve 10. The crank angles θ ₂ and θ ₄ are crank angles that give an inflection point to the graph of the valve lift. Valve opening acceleration, as shown in FIG. _{4 (B), θ 1 ~θ} 2 section is positive, theta ₂ through? ₄ segment is negative, theta ₄ through? ₅ section becomes positive again. Controller 9 is a least the exhaust top dead center and later, after time the crank angle theta is theta _1, starts the fuel injection. As a result, mixing of fuel and exhaust gas in the intake port 1 is suppressed. In order to more reliably suppress the mixing of the fuel and the exhaust flow, it is preferable to shift the fuel injection start timing in a more retarded direction. The control device 9 of the present embodiment stops the fuel injection from the fuel injection port 8 until the opening acceleration changes from positive to negative in the intake stroke (until a predetermined time elapses). As a result, the fuel injection is performed in a state where the exhaust flow in the intake port 1 is being introduced into the cylinder 23, and therefore, the mixing of the fuel and the exhaust flow in the intake port 1 may be suppressed. Will rise significantly.

The timing at which fuel injection ends can vary depending on the total fuel injection amount and fuel pressure, but it is preferable to end fuel injection within the intake stroke. For this reason, it is preferable that the fuel pressure be controlled to increase as the engine speed or the engine load increases. This makes it easy to inject a desired amount of fuel into the intake stroke. The timing and end timing of the intake stroke is started is arbitrarily set, may be perfectly matched to the theta ₁ through? ₅ section, it may not be matched. By using a known variable valve timing mechanism, it is possible to shift the intake stroke from theta ₁ through? ₅ interval in the advance direction or the retard direction.

[2. Action]
When the intake valve 10 is opened, the internal pressure of the intake port 1 decreases to a negative pressure, and exhaust gas is injected from the exhaust gas recirculation port 6 through the exhaust return passage 5. At this time, since the fuel injection is stopped, the exhaust flow mainly flows into the cylinder 23 from the intake port 1. The exhaust flow is introduced into the cylinder 23 through a gap between the umbrella portion 12 of the intake valve 10 and the opening 2 as indicated by a black arrow in FIG. In the cylinder 23, the exhaust flow passes through the head surface 19 of the exhaust valve 15, flows to the vicinity of the cylinder liner 24 of the cylinder block 22, and forms a swirling flow along the surface of the cylinder liner 24.

  When the opening acceleration of the intake valve 10 changes from positive to negative during the intake stroke of the engine 20, fuel is injected from the fuel injection port 8 as shown in FIG. The fuel is introduced into the cylinder 23 together with the exhaust flow while being mixed with the external air flow (open arrows in FIG. 6) which is drawn into the intake port 1 from the intake manifold side. At this time, since the wall surface above the center line of the intake port 1 (the outer surface on the turning side) and the umbrella back surface 13 of the intake valve 10 are covered in a curtain shape by the exhaust gas flow, fuel droplets are 1 does not easily adhere to the inner wall surface or the umbrella back 13. Further, since the fuel injection direction is along the exhaust flow, the fuel or the air-fuel mixture is less likely to be mixed into the exhaust flow, and is introduced into the cylinder 23 on the surface layer of the exhaust flow.

  As shown in FIG. 7, the fuel in the state of being covered on the surface layer of the exhaust flow is also conveyed in the cylinder 23 along with the exhaust flow along the swirl flow. Thereby, fuel adhesion to the cylinder liner 24 in the cylinder 23 is suppressed. Further, the fuel transported as droplets to the cylinder 23 takes heat (vaporization latent heat) from the surrounding air when vaporizing in the cylinder 23 and lowers the temperature in the cylinder. Thereby, the charging efficiency and the volumetric efficiency are increased, and the knocking resistance of the engine 20 is improved.

[3. effect]
(1) In the engine 20 described above, the exhaust flow is injected toward the opening 2 so that the diffusion shape of the exhaust flow is formed in a cone or fan shape with a small divergence angle from the exhaust gas recirculation port 6 to the opening 2. be able to. As a result, mixing of the fuel and the exhaust gas flow can be suppressed (or avoided), and the combustion state in the cylinder 23 can be improved.
Further, even during the intake stroke, the fuel injection is stopped until the intake valve 10 is opened. Therefore, it is possible to suppress the fuel from adhering to the inner wall surface of the intake port 1 and the back surface 13 of the intake valve 10. it can. Further, since the fuel injection is started after the intake valve 10 is opened, the mixture of fuel and air and the droplets of the fuel are layered along the flow of the exhaust gas injected from the exhaust gas recirculation port 6 into the cylinders 23. Can be conveyed inside. As a result, the fuel hardly adheres to the cylinder liner 24 in the cylinder 23, and the combustion state in the cylinder 23 can be improved.

(2) In the above-described engine 20, since the fuel injection is stopped until a predetermined time elapses after the intake valve 10 opens, the conical or fan-shaped exhaust flow having a small divergence angle precedes the fuel. It can be introduced into the cylinder 23. Therefore, the mixing of the fuel and the exhaust gas flow can be suppressed (or avoided), and the combustion state in the cylinder 23 can be further improved.
Further, by injecting the fuel in the intake stroke after a predetermined time has elapsed, the fuel can be introduced into the cylinder 23 on the surface layer of the exhaust flow while being mixed with fresh air. Thereby, the combustion state in the cylinder 23 can be further improved.

  (3) In the engine 20, the start time of the fuel injection is controlled based on the opening acceleration of the intake valve 10. Thus, fuel can be injected in consideration of the timing of drawing the exhaust gas flow from the intake port 1 into the cylinder 23, and the mixing state of fuel and fresh air can be optimized in the intake port 1. it can. Thereby, the combustion state in the cylinder 23 can be improved.

  (4) In the engine 20, the fuel injection is stopped until the opening acceleration changes from positive to negative during the intake stroke. Thereby, it is possible to accurately grasp the timing at which the action of drawing air by the umbrella portion 12 of the intake valve 10 is being reduced. That is, the exhaust flow in the intake port 1 immediately after the valve is opened is drawn into the cylinder 23, and the fresh air is drawn into the vicinity of the fuel injection port 8, so that the fuel can be injected. And mixing of fresh air and fuel can be promoted. Therefore, the combustion state in the cylinder 23 can be improved.

  (5) In the engine 20, the higher the engine speed or the engine load, the higher the fuel pressure. This makes it easy to inject a desired amount of fuel into the intake stroke, thereby ensuring the output of the engine 20 and improving the combustion state in the cylinder 23. In addition to this, as the engine speed or the engine load is higher, the effect of suppressing the mixing of the fuel and the exhaust gas can be enhanced by delaying the start timing of the fuel injection.

  (6) In the engine 20, the fuel is injected in a direction along the injection direction of the exhaust flow injected from the exhaust gas recirculation port 6. Thereby, the fuel spray can be easily gathered (easily put on) on the surface layer of the exhaust flow, and the mixing of the fuel and the exhaust flow can be suppressed efficiently. Therefore, the combustion state in the cylinder 23 can be further improved. Further, since the fuel easily flows in the cylinder 23 along the exhaust gas flow, the amount of fuel adhering to the head surface 19 of the exhaust valve 15 and the cylinder liner 24 can be reduced.

  (7) In the engine 20, the fuel injection port 8 is arranged upstream of the exhaust gas recirculation port 6, that is, the exhaust gas recirculation port 6 is arranged downstream of the fuel injection port 8. Thereby, fuel can be injected toward the inner wall surface of the intake port 1 covered with the exhaust flow. Therefore, the amount of fuel attached to the port can be reduced. Further, since the in-cylinder direct injection rate of the fuel increases, the intake air cooling effect in the cylinder 23 can be enhanced.

[4. Modification]
The engine 20 shown in FIG. 8 changes the position of the fuel injection port 8 in the above-described embodiment, and faces the exhaust recirculation port 6 across the center line of the intake port 1 (that is, from the center line of the intake port 1). Are also disposed on the lower wall surface). The position of the fuel injection port 8 is set on the inner wall surface on the upstream side of the exhaust gas recirculation port 6 and below the intake port 1 in a longitudinal section. On the other hand, the fuel injection direction is the direction along the injection direction of the exhaust flow injected from the exhaust gas recirculation port 6, as in the above embodiment. By arranging the exhaust gas recirculation port 6 on the wall surface on the side opposite to the fuel injection port 8 in this manner, fuel can be injected toward the wall surface of the intake port 1 covered with the exhaust flow in a curtain shape. Thus, the amount of fuel adhering to the port and the amount of fuel adhering to the head surface 19 of the exhaust valve 15 and the cylinder liner 24 can be reduced, so that the combustion state in the cylinder 23 can be improved.

  In the engine 20 shown in FIG. 9, the position of the exhaust return passage 5 and the position of the injector 7 in the above-described embodiment are interchanged. However, the exhaust return passage 5 is extended to near the center line of the intake port 1 so that the exhaust gas recirculation port 6 is located downstream of the fuel injection port 8. The direction in which the exhaust gas is injected from the exhaust gas recirculation port 6 is set to the direction toward the opening 2. Further, the fuel injection direction is set in a direction along the exhaust flow injection direction. Such a structure also has the same effect as the above-described embodiment.

  In the above-described embodiment, the injector 7 that injects fuel in two directions substantially toward the center of the two openings 2 has been illustrated. However, the fuel injection direction when the engine 20 is viewed from above is not limited to this. For example, the fuel may be injected toward a branch point (siamese portion) where the intake port 1 branches toward the two openings 2. This allows a portion of the fuel to adhere to the vicinity of the siamese portion and be vaporized. Further, by providing the injectors 7 for each of the two openings 2, it is possible to further improve the transportability of the fuel into the cylinder 23.

  The structure of the engine 20 described in the above embodiment is not limited to the multi-port type gasoline engine, but is not a siamese shape even in a single port or multi-port type. It is also possible to apply to a gasoline engine or a diesel engine provided. As long as the internal combustion engine has at least the exhaust gas recirculation port 6 and the fuel injection port 8 in the intake port 1, the same structure as in the above-described embodiment can be applied, and the same effect as in the above-described embodiment can be applied. Can be obtained.

1 intake port 2 opening 5 exhaust return passage 6 exhaust recirculation port (gas injection port)
7 Injector 8 Fuel injection port 9 Control device 10 Intake valve 23 Cylinder 31 Cam angle sensor 32 Crank angle sensor

Claims (6)

An intake valve that opens and closes the cylinder-side opening of the intake port,
A gas injection port for injecting gas toward the opening in the intake port,
A fuel injection port that is provided upstream of the gas injection port and injects fuel into the intake port during an intake stroke;
In the intake stroke, the fuel injection from the fuel injection port is stopped at least until the intake valve is opened, and the fuel injection is started after the intake valve in which the gas flows into the cylinder is opened. Equipment and
The gas injection port injects the gas toward a stem of the intake valve,
The engine, wherein the fuel injection port injects the fuel in a direction along a direction in which the gas injected from the gas injection port is parallel to the direction in which the gas is injected. The control device may stop fuel injection from the fuel injection port until a predetermined time has elapsed since the intake valve was opened, and may start the fuel injection after the predetermined time has elapsed. The engine of claim 1. The engine according to claim 2, wherein the control device sets the predetermined time based on an opening acceleration of the intake valve. 4. The engine according to claim 2, wherein the control device sets a time required for the opening acceleration of the intake valve to change from positive to negative in the intake stroke as the predetermined time. 5. The engine according to any one of claims 1 to 4, wherein the control device increases the pressure of the fuel as the engine speed or the engine load increases. The engine according to any one of claims 1 to 5 , wherein the gas injected from the gas injection port is a part of exhaust gas of the engine.

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