JP2012188937A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of maintaining performance in the case of directly injecting fuel into a cylinder without providing a direct injection type injector, which directly injects fuel into the cylinder, in the cylinder by accurately setting the injecting condition of the fuel to an intake passage.SOLUTION: Fuel from an injector 10 is straightly injected toward an intake opening 22 along an upper wall part of the intake passage 5, the intake air is led toward the intake opening 22 from an upstream side of a fuel injection opening 23 of the injector 10, and the injecting direction of the fuel and the leading direction of the intake air are paralleled. The fuel is mixed with the intake air without disturbing atomization, and is flown into a combustion chamber 6 without adhesion to the wall surface.

Description

  In the present invention, by accurately setting the state of fuel injection into the intake passage, performance is improved without directly providing a fuel injection device in the cylinder (inside the cylinder) directly in the cylinder. The present invention relates to an internal combustion engine.

  2. Description of the Related Art As an internal combustion engine (engine), an engine is known that includes a direct injection injector that is provided inside a cylinder (in a cylinder) and injects fuel directly into the cylinder, and a port injection injector that injects fuel into an intake passage. (For example, refer to Patent Document 1).

  In an engine equipped with a direct-injector and a port-injector, high-pressure fuel is directly injected from the direct-injector into the cylinder, so that the latent heat of vaporization of the fuel is used for cooling the intake air and the temperature of the mixture is lowered. The occurrence of knocking can be suppressed. Furthermore, since the air density can be increased by cooling the intake air, the amount of intake air at the full load can be increased to improve the performance. Further, by injecting fuel from the port injector into the intake passage, homogenization of the air-fuel mixture can be promoted in a low-load operating region where the flow in the cylinder is weak and the air-fuel mixture homogeneity is poor.

  However, in an engine provided with a direct injection injector and a port injection injector, the tip of the direct injection injector mounted in the cylinder is exposed to high-temperature and high-pressure combustion gas. For this reason, even when fuel is injected from the port injector to promote homogenization of the air-fuel mixture, in order to cool the tip of the direct injection by the cooling action of the fuel injection, the fuel from the direct injection injector The current situation is that it is necessary to continue the injection, and fuel injection cannot be performed only from the port injector. In addition, a part of the fuel injected from the direct injection injector collides with the wall of the combustion chamber and burns in a liquid film, so that there is a problem that particulate matter is largely discharged. Further, since it is necessary to inject fuel at a high pressure from the direct injection injector, there is a possibility that the power loss of the high-pressure pump may affect the performance.

  In addition, direct injection injectors need to ensure temperature resistance and pressure resistance, and further, because the tip is exposed to combustion gas, carbonization of combustion products and fuels tends to cause deposits to accumulate depending on operating conditions, Deposit measures were required. For this reason, the internal combustion engine provided with the direct injection injector has a problem that the cost of the fuel injection system increases.

JP 2009-228447 A

  The present invention has been made in view of the above situation, by accurately controlling the state of fuel injection during the intake stroke without providing a direct injection injector for directly injecting fuel into the cylinder, An object of the present invention is to provide an internal combustion engine capable of maintaining the performance when fuel is directly injected into a cylinder and obtaining high performance.

  In order to achieve the above object, an internal combustion engine according to a first aspect of the present invention includes an injector that injects fuel from a fuel injection port into an intake passage, an intake opening that communicates the intake passage and the inside of the cylinder, and an intake air Fuel injection means including at least intake stroke injection means for injecting fuel from the injector during the stroke, and fuel is injected from the injector during the intake stroke, and fuel is introduced into the cylinder from the intake opening. Control means for forming an air-fuel mixture inside the cylinder, the intake passage has an upper wall portion extending linearly toward the intake opening, and the injector has an injection direction of the fuel in the upper wall The fuel injection port is arranged so as to be parallel along the portion, and the intake air sent to the intake passage is from the upstream side of the fuel injection port of the injector. Serial introduced toward the suction opening, the direction of introduction of the injection direction and the intake air of the fuel, characterized in that it is in parallel.

  In the present invention according to claim 1, fuel is injected into the intake passage during the intake stroke by the intake stroke injection means, and the fuel flows into the cylinder when the intake valve is open. Fuel from the injector is injected straight along the upper wall toward the intake opening, intake air is introduced from the upstream side of the fuel injection opening toward the intake opening, and fuel spray flows into the intake air flow. The fuel is prevented from adhering to the wall surface without being disturbed by the air and mixed with the intake air and flows into the cylinder.

  As a result, the occurrence of knocking is suppressed by using the latent heat of vaporization of the fuel for cooling the intake air without providing a direct injection injector for directly injecting the fuel into the cylinder. The performance can be improved by increasing the density and increasing the amount of intake air at full load.

  For this reason, when the fuel is directly injected into the cylinder by accurately controlling the state of the fuel injection during the intake stroke without providing the cylinder with a direct injection injector that directly injects the fuel into the cylinder. It is possible to maintain high performance and maintain high performance.

  The internal combustion engine of the present invention according to claim 2 is the internal combustion engine according to claim 1, wherein the intake air sent to the intake passage is directed from the upstream side of the fuel injection port of the injector to the intake opening. The fuel injection direction and the intake air introduction direction are made parallel to each other.

  In the present invention according to claim 2, since the intake air is introduced from the upstream side of the fuel injection port toward the intake opening, the fuel spray is not disturbed and flows into the cylinder without adhering to the wall surface. To do.

  The internal combustion engine of the present invention according to claim 3 is the internal combustion engine according to claim 2, wherein the upper wall portion of the intake passage is a spray passage through which fuel injected from the injector flows, The intake passage is formed with a guide portion that guides the intake air into the spray passage and introduces the intake air into the spray passage.

  In the third aspect of the present invention, the fuel is injected into the spray passage and the intake air is introduced from the guide portion, so that the intake air is rectified and introduced in parallel from the upstream side of the fuel, so that the fuel is reliably supplied to the inside of the cylinder. Can be allowed to flow into.

  The internal combustion engine of the present invention according to claim 4 is the internal combustion engine according to claim 3, wherein the intake passage and the spray passage are formed over the intake port and the intake manifold, and the intake manifold or the intake port is connected to the intake manifold or the intake port. The main body of the injector is disposed at a position of the spray passage located, and the intake passage of the intake manifold is communicated with the intake passage of the intake port via a bent portion, and the spray passage from the intake manifold portion The guide portion is formed on the bent outer peripheral side of the bent portion so as to introduce the intake air into the bent portion.

  In the present invention according to claim 4, even in an engine designed to be supplied with air from below, intake air can be introduced in parallel from upstream to the fuel in the spray passage.

  An internal combustion engine according to a fifth aspect of the present invention is the internal combustion engine according to any one of the first to fourth aspects, wherein the fuel injected from the fuel injection port of the injector is a maximum of an intake valve. The injection is directed toward the central portion of the intake opening during lift.

  Since the fuel is injected toward the central portion of the intake opening at the time of the maximum lift of the intake valve, it is possible to greatly suppress the adhesion of the fuel to the wall surface.

  The internal combustion engine of the present invention does not include a direct injection injector that directly injects fuel into the cylinder, and accurately controls the state of fuel injection during the intake stroke so that the fuel is injected into the cylinder. The performance in the case of direct injection can be maintained and high performance can be obtained.

1 is a schematic configuration diagram showing an entire internal combustion engine according to an embodiment of the present invention. It is a principal part block diagram in FIG. It is an external appearance perspective view of an intake port. It is a top view around the intake port for explaining the spread of fuel. It is a side view around the intake port explaining the spread of fuel. It is a graph showing the relationship between an engine speed and fuel pressure.

  The internal combustion engine of the present invention will be described with reference to FIGS.

  1 is a schematic configuration of an entire internal combustion engine according to an embodiment of the present invention, FIG. 2 is a specific configuration around an intake port, FIG. 3 is a perspective view showing the appearance of the intake port, and FIG. FIG. 5 shows a top view around the intake port for explaining the spread of the fuel, and FIG. 5 shows a side view around the intake port for explaining the spread of the fuel. FIG. 6 shows the relationship between the engine speed and fuel pressure.

  As shown in FIGS. 1 and 2, a spark plug 3 is attached to a cylinder head 2 of an engine body (hereinafter referred to as an engine) 1 that is an internal combustion engine (engine) for each cylinder, and a high voltage is applied to the spark plug 3. Is connected to the ignition coil 4. In the cylinder head 2, an intake port 8 constituting the intake passage 5 is formed for each cylinder, and an intake valve 7 is provided on the combustion chamber 6 side of each intake passage 5 of the intake port 8. The intake valve 7 is opened and closed in accordance with a cam of a camshaft (not shown) that rotates in accordance with engine rotation, and opens and closes the intake opening 22 between each intake passage 5 and the combustion chamber 6 (intake passage 5 and combustion). (Communication / blocking of the chamber 6).

  One end of an intake manifold 9 is connected to each intake port 8, and the intake passage of the intake manifold 9 communicates with each intake port 8. The intake passage of the intake manifold 9 extends from below and communicates with the intake passage 5 of the intake port 8. An electromagnetic fuel injection valve (injector) 10 is attached to the intake manifold 9, and a fuel injection port 23 of the injector 10 is arranged in the intake passage 5 of the intake port 8 so as to face the intake opening 22. Fuel from a fuel tank (not shown) is supplied to the injector 10 via a fuel pipe 21.

  The cylinder head 2 is provided with an exhaust port 11 for each cylinder, and an exhaust valve 12 is provided on the combustion chamber 6 side of each exhaust port 11. The exhaust valve 12 is opened and closed in accordance with a cam of a camshaft (not shown) that rotates in accordance with the engine rotation, so that the exhaust ports 11 and the combustion chamber 6 are communicated / blocked. One end of an exhaust manifold 13 is connected to each exhaust port 11, and the exhaust manifold 13 communicates with each exhaust port 11.

  In addition, since such an engine is a well-known thing, it abbreviate | omitted about the detail of the structure.

  An intake pipe 14 is connected to the upstream side of the intake manifold 9. An electromagnetic throttle valve 15 is attached to the intake pipe 14, and a throttle position sensor 16 for detecting the valve opening degree of the throttle valve 15 is provided. 15 is operated according to the depression amount of the accelerator pedal.

  An air flow sensor 17 that measures the amount of intake air is provided upstream of the throttle valve 15. As the air flow sensor 17, a Karman vortex type or hot film type air flow sensor is used. A surge tank 18 is provided in the intake pipe 14 between the intake manifold 9 and the throttle valve 15.

  The engine 1 is provided with a crank angle sensor 25 that detects a crank angle and obtains an engine rotation speed (Ne), and a water temperature sensor 26 that detects a cooling water temperature. The fuel pipe 21 is provided with a fuel pressure sensor 27 that detects the pressure of the fuel supplied to the injector 10.

  The ECU (electronic control unit) 31 includes an input / output device, a storage device (ROM, RAM, etc.), a central processing unit (CPU), a timer counter, and the like. The ECU 31 performs comprehensive control of the engine 1.

  Various sensors such as the throttle position sensor 16, the air flow sensor 17, the crank angle sensor 25, the water temperature sensor 26, and the fuel pressure sensor 27 described above are connected to the input side of the ECU 31, and detection information from these sensors is input. The Further, the ECU 31 receives (or stores) information on the lift amount and lift timing of the intake valve 7 and the exhaust valve 12.

  On the other hand, the output side of the ECU 31 is connected to various output devices such as the ignition coil 4, the throttle valve 15, and the drive device for the injector 10. These various output devices include a fuel injection amount calculated by the ECU 31 based on detection information from various sensors, a fuel injection period, a fuel injection timing, an ignition timing, and operating states of the intake valve 7 and the exhaust valve 12 (valve operating states). ) Etc. are output respectively.

  Based on detection information from various sensors, the air-fuel ratio is set to an appropriate target air-fuel ratio, an amount of fuel corresponding to the target air-fuel ratio is injected from the injector 10 at an appropriate timing, and the throttle valve 15 is opened appropriately. The spark ignition is performed at an appropriate timing by the spark plug 3.

  The engine 1 of this embodiment is configured to inject fuel from the injector 10 during the intake stroke and to inject fuel from the injector 10 during the exhaust stroke. When the injected fuel reaches the vicinity of the intake valve 7, if the intake valve 7 is opened, it is defined as intake stroke injection, and the case where the intake valve 7 is not opened is defined as exhaust stroke injection. . Actually, there is a time delay such as a delay in the opening of the injector needle valve or a transport delay from the injector 10 to the intake valve 7 until the fuel reaches the vicinity of the intake valve 7 from the injector drive command. The command may be issued during the exhaust stroke.

  By injecting fuel during the intake stroke (while the intake valve 7 is open), the fuel is prevented from adhering to the intake passage 5 and the umbrella portion of the intake valve 7 to cool the latent heat of vaporization of the intake air. Available to: For this reason, the temperature of the air-fuel mixture is lowered to suppress the occurrence of knocking, and the air density is increased to increase the amount of intake air at full load, thereby maximizing the effect of intake air cooling even for port injection. be able to.

  By injecting fuel from the injector 10 during the exhaust stroke, an air-fuel mixture in which fuel and air are sufficiently homogeneously mixed inside the intake passage 5 is obtained. Since the injector 10 is provided in the intake port 8, the injector 10 is not exposed to high-temperature and high-pressure combustion gas, and has a simple mounting structure that does not require securing of temperature resistance and pressure resistance. In addition, since it is not necessary to inject high-pressure fuel, the influence on performance due to power loss of the pump can be reduced.

  As shown in FIG. 2, the intake port 8 and the intake opening 22 are connected by a cylindrical portion 20 (throat portion), and fuel injection by the injector 10 during the intake stroke is performed when the intake valve 7 is at the maximum lift. The fuel passes through between the seat of the intake opening 22 and the umbrella portion of the intake valve 7 so that the fuel is directed into the combustion chamber 6, that is, toward the center of the intake opening 22.

  The fuel from the injector 10 is injected straight along the upper wall portion of the intake passage 5 toward the intake opening 22, and the intake air is directed from the upstream side of the fuel injection port 23 of the injector 10 toward the intake opening 22. The fuel injection direction and the intake air introduction direction are made parallel. Thus, the spray of fuel is not disturbed by the flow of the intake air, and the adhesion of the fuel to the wall surface is suppressed, mixed with the intake air, and flows into the combustion chamber 6 (inside the cylinder).

  The configuration of the intake port 8 and the intake manifold 9 forming the intake passage 5 will be specifically described with reference to FIGS.

  The intake passage 5 is formed over the intake port 8 and the intake manifold 9, and the intake passage 5 is provided with an upper wall portion that extends linearly toward the intake opening 22. The upper wall portion serves as a spray passage 33 through which fuel injected from the injector 10 flows, and the main body of the injector 10 is disposed at a portion of the spray passage 33 located in the intake manifold 9 (or the intake port 8).

  A fuel injection port 23 of the injector 10 faces the intake opening 22 and faces the intake passage 5 of the intake port 8. The intake passage 5 is formed with a guide portion 34 that guides the intake air to the spray passage 33 and introduces the intake air to the spray passage 33. The guide portion 34 is formed in the intake passage of the intake manifold 9 and the intake port 8 so as to introduce intake air from the portion of the intake manifold 9 to the spray passage 33, and the intake opening 22 from the upstream side of the fuel injection port 23 of the injector 10. Intake air is introduced toward

  As a result, fuel is injected from the fuel injection port 23 of the injector 10 into the spray passage 33 (indicated by a solid line arrow in FIG. 2), and intake air is introduced from the upstream side of the fuel injection port 23 by the guide portion 34. For this reason, the intake air is rectified in the spray passage 33 and introduced from the upstream of the fuel in parallel with the injection direction (indicated by a white arrow in FIG. 2), and the shape of the intake manifold 9 is supplied with air from below. However, the spray is not disturbed by the flow of the intake air.

  Accordingly, the fuel can be reliably injected toward the combustion chamber 6 (inside the cylinder), and the fuel spray is flowed into the intake air flow in the middle / high rotation speed range of the engine 1 where the intake air flow velocity becomes high. However, it becomes possible to send the fuel into the combustion chamber 6 with greatly reduced fuel adhesion to the upper wall of the intake port 8 (intake passage 5).

  The fuel injection port 23 is set so that the fuel injected from the injector 10 described above is injected into the intake opening 22 with a predetermined spread. The fuel spread will be described with reference to FIGS. As shown in the figure, the internal combustion engine of the present embodiment is provided with two intake openings 22 and intake ports 8 for one cylinder, and fuel is injected from one injector 10 to the two intake ports 8. The

  As shown in FIG. 4, in the state of the cylinder as viewed from above, the fuel injected from the fuel injection port 23 of the injector 10 is set to have a wide range (indicated by a one-dot chain line in the drawing) in the range inside the intake opening 22. Is done. The fuel spread angle α is preferably 12 degrees or more, for example.

  As shown in FIG. 5, in the state of the cylinder in a side view, the fuel injected from the fuel injection port 23 of the injector 10 is in the range inside the intake opening 22 from the valve shaft when the intake valve 7 is fully lifted to the cylinder. The width of the range on the center side is set to be widened (indicated by a dashed line in the figure). For example, it is desirable to secure a fuel spread angle β of 6 or more.

  The spread of fuel in a side view of the cylinder is defined as follows.

  A portion of the valve seat of the intake valve 7 at the time of maximum lift of the intake valve 7 is A.

  The seat portion of the intake opening 22 is denoted by B.

  A line extending from the part A along the lower surface of the intake passage 5 as a starting point is defined as a line C (indicated by a dotted line in the figure).

  A line (a line parallel to the line C) extending from the part B along the lower surface of the intake passage 5 is defined as D (shown by a dotted line in the figure).

  A boundary line between the intake port 8 and the cylindrical portion 20 is represented by E (indicated by a one-dot chain line in the figure).

  Assume that the intersection of line C and boundary E is F1, and the intersection of line D and boundary E is F2.

  In a state in which the cylinder is viewed from the side, the fuel injected from the fuel injection port 23 of the injector 10 is injected so as to pass between the intersection point F1 and the intersection point F2. The width of the range from the valve shaft to the center of the cylinder at the time of maximum lift is set (indicated by a dashed line in the figure).

  As shown in FIGS. 4 and 5, the fuel injected from the fuel injection port 23 of the injector 10 is set to expand the width of the range inside the intake opening 22 in the state of the top view of the cylinder, and the side surface of the cylinder In the viewing state, the width inside the intake opening 22 is set to be narrower than that in the top view of the cylinder, so that the fuel spray is fan-shaped with a large spread in the top view and a small spread in the side view. Further, it is desirable that the fuel injection direction is set so as to pass through a range in the vicinity of the bent portion of the lower surface of the intake port 8 (boundary line with the tubular portion 20) from the center of the intake port.

  For this reason, even if the spray of fuel flows into the intake air flow in the middle / high rotation speed region of the engine 1 where the intake air flow rate becomes fast, the fuel adheres to the upper wall of the intake port 8 (intake passage 5). can do. In addition, the fuel spray is fan-shaped with a wide spread in the top view and a narrow spread in the side view, and the surface area of the spray (that is, the contact area with the air) is secured to prevent mixing with the intake air. There is no risk of deteriorating exhaust gas performance. Further, the penetration force of the spray does not become too strong, and there is no possibility that the fuel adheres to the cylinder wall surface (cylinder liner) and the engine oil is diluted.

  When the spread of the fuel in the state of the top view of the cylinder is narrowed, it becomes a stick-like spray, the surface area of the spray (that is, the contact area with the air) cannot be secured, and mixing with the intake air is hindered. Further, the penetration force of the spray becomes strong, and the fuel adheres to the wall surface (cylinder liner) of the cylinder and the engine oil is diluted.

  In the present embodiment, the pressure (fuel pressure) of the fuel injected from the injector 10 is set so as to increase according to the rotational speed of the engine 1 (fuel pressure setting means). That is, as shown in FIG. 6, the fuel pressure is set to increase as the rotational speed of the engine 1 increases (as the rotational speed increases). By increasing the fuel pressure, the flow rate of the fuel spray increases even in a high rotational speed region (predetermined rotational speed region), making it difficult for the spray to flow further into the intake air flow. 5) Fuel adhesion to the upper wall can be further reduced.

  As described above, the engine 1 of this embodiment accurately controls the state of fuel injection during the intake stroke, and does not include a direct injection injector that directly injects fuel into the cylinder. The occurrence of knocking can be suppressed by using the latent heat of vaporization for cooling the intake air, and the performance can be improved by increasing the air density at the full load by increasing the air density by cooling the intake air. Further, even when the pressure of the intake port is higher than the pressure of the exhaust port, it is possible to reduce the blow-through of fuel to the exhaust port and prevent the unburned HC from being discharged. Furthermore, since the flow induced by fuel injection intensifies the turbulence in the cylinder, it is possible to promote flame propagation and obtain good combustion.

  For this reason, when the fuel is directly injected into the cylinder by accurately controlling the state of the fuel injection during the intake stroke without providing the cylinder with a direct injection injector that directly injects the fuel into the cylinder. It is possible to maintain high performance and maintain high performance.

  In the present invention, by accurately setting the state of fuel injection into the intake passage, performance is improved without directly providing a fuel injection device in the cylinder (inside the cylinder) directly in the cylinder. It can be used in the industrial field of internal combustion engines.

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder head 3 Spark plug 4 Ignition coil 5 Intake passage 6 Combustion chamber 7 Intake valve 8 Intake port 9 Intake manifold 10 Fuel injection valve (injector)
DESCRIPTION OF SYMBOLS 11 Exhaust port 12 Exhaust valve 13 Exhaust manifold 14 Intake pipe 15 Throttle valve 16 Throttle position sensor 17 Air flow sensor 18 Surge tank 21 Fuel pipe 22 Intake opening 23 Fuel injection port 25 Crank angle sensor 26 Water temperature sensor 27 Fuel pressure sensor 31 ECU
33 Spray passage 34 Guide section

Claims (5)

An injector for injecting fuel into the intake passage from the fuel injection port;
An intake opening communicating the intake passage and the inside of the cylinder;
Fuel injection means including at least intake stroke injection means for injecting fuel from the injector during the intake stroke;
Control means for injecting fuel from the injector during the intake stroke and introducing fuel into the cylinder from the intake opening to form an air-fuel mixture inside the cylinder;
The intake passage has an upper wall portion extending linearly toward the intake opening,
The internal combustion engine, wherein the injector has the fuel injection port arranged so that the fuel injection direction is parallel to the upper wall portion. The internal combustion engine according to claim 1,
The intake air sent to the intake passage is introduced from the upstream side of the fuel injection port of the injector toward the intake opening, and the fuel injection direction and the intake air introduction direction are made parallel to each other. An internal combustion engine. The internal combustion engine according to claim 2,
The upper wall portion of the intake passage is a spray passage through which fuel injected from the injector flows,
The internal combustion engine, wherein the intake passage is formed with a guide portion that guides the intake air into the spray passage and introduces the intake air into the spray passage. The internal combustion engine according to claim 3,
The intake passage and the spray passage are formed across an intake port and an intake manifold;
A main body of the injector is disposed at a portion of the spray passage located in the intake manifold or the intake port;
The intake passage of the intake manifold communicates with the intake passage of the intake port via a bent portion,
The internal combustion engine, wherein the guide portion is formed on a bent outer peripheral side of the bent portion so as to introduce the intake air from a portion of the intake manifold into the spray passage. The internal combustion engine according to any one of claims 1 to 4,
The internal combustion engine, wherein the fuel injected from the fuel injection port of the injector is directed toward a central portion of the intake opening at the time of maximum lift of the intake valve.

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