JP2010077825A - Cylinder injection type spark ignition internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform control of fuel injection, in particular, control of contraction suppression, according to the operation state of an engine, in a cylinder injection type spark ignition internal combustion engine equipped with a slit-like injection hole and a fuel injection valve that forms a fan-shaped fuel spray in a combustion chamber. <P>SOLUTION: In this cylinder injection type spark ignition internal combustion engine equipped with the slit-like injection hole 28 and the fuel injection valve 18 forming the flat fan-shaped fuel spray in the combustion chamber 5, near each of injection hole inlet edge parts on sides of two side wall faces 28a in the slit-like injection hole 28 for restricting widening of a fan-shaped central angle α of the fuel spray 35, a fuel flow control valve 30 having a rotary shaft 30a fixed in parallel with the injection hole inlet edge part, and a plate-like member 30b having one end connected to the rotary shaft 30a and rotatable around the rotary shaft 30a, are disposed resoectively. During fuel injection, the rotational position of the plate-like member 30b is controlled, and the fuel flow along the surface of the plate-like member 30b is made to flow into the slit-like injection hole 28 while being deflected with respect to an injection central axis X of the fuel hole 28. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a direct injection spark ignition internal combustion engine.

  In a cylinder injection spark ignition internal combustion engine having a fuel injection valve for injecting fuel into a combustion chamber, the pressure inside the injected fuel spray (that is, near the injection center axis of the injection hole) is low and the outside of the fuel spray When the pressure of the fuel spray is high, the fuel spray may be drawn inward and contracted due to the pressure difference (hereinafter referred to as “constricted flow”). The occurrence and the degree of contraction change depending on the operating state of the engine (mainly in-cylinder pressure). The generation of unintended contracted flow is not preferable because it causes unintended fuel spray behavior and adversely affects the combustion state.

  Therefore, in a cylinder injection spark ignition internal combustion engine provided with an inwardly open fuel injection valve for injecting fuel into a combustion chamber in a hollow cone shape, a wall surface for fuel spray guidance is provided in the vicinity of the fuel injection hole of the fuel injection valve, A cylinder injection spark ignition internal combustion engine in which the fuel spray is prevented from contracting by moving the fuel spray along the wall surface is known (see Patent Document 1).

JP 2005-201062 A

  However, in this in-cylinder spark-ignition internal combustion engine, the effect of suppressing the contraction flow depends on the shape of the wall surface for guiding the fuel spray. There is a problem that it is difficult to control.

  By the way, the necessity for such control of contraction control is similarly applied to a cylinder injection spark ignition internal combustion engine having a fuel injection valve which has a slit-like injection hole and forms a flat fan-shaped fuel spray in the combustion chamber. Exists. This will be briefly described with reference to FIG. FIG. 13 is a schematic view showing the spread of fuel spray in the combustion chamber as viewed from the top of the combustion chamber. 5 is a combustion chamber, 6 is an intake valve, 8 is an exhaust valve, and 18 is a fuel injection valve. It can be seen that the fuel spray 35b under the high in-cylinder pressure indicated by the solid line has a smaller fan-shaped central angle α and is contracted compared to the fuel spray 35a under the low in-cylinder pressure indicated by the broken line. As a result of the contraction, the fuel spray concentrates and travels through the combustion chamber, so the penetration force (penetration) increases. For example, particulate matter in the exhaust gas due to fuel adhering to the bore formed in the piston ( Problems such as an increase in PM) occur.

  Accordingly, the present invention provides a fuel injection control in accordance with the operating state of an engine in a cylinder injection spark ignition internal combustion engine having a fuel injection valve that has a slit-shaped injection hole and forms a fan-shaped fuel spray in a combustion chamber. In particular, it is an object of the present invention to provide an in-cylinder injection spark ignition internal combustion engine that performs control of contraction flow suppression.

  In order to solve the above-mentioned problem, according to the invention described in claim 1, a cylinder injection type spark ignition internal combustion engine having a fuel injection valve provided with a slit-like nozzle hole and forming a flat fan-shaped fuel spray in the combustion chamber. In the engine, a rotation shaft fixed in parallel with the nozzle hole inlet edge in the vicinity of the nozzle hole inlet edge on the two side wall surfaces in the slit-shaped nozzle hole for restricting the spread of the fan-shaped central angle of the fuel spray. A fuel flow control valve having a plate-like member having one end connected to the rotary shaft and rotatable around the rotary shaft, and controlling the rotational position of the plate-like member during fuel injection, An in-cylinder injection spark ignition internal combustion engine is provided in which a fuel flow along a surface of a plate-like member is deflected with respect to an injection center axis of the injection hole and flows into the injection hole.

  That is, in the first aspect of the invention, by controlling the rotational position of the plate-shaped member, the fuel flow flowing into the slit-shaped nozzle hole is deflected with respect to the injection center axis of the nozzle hole, and the slit-shaped nozzle An uneven fuel flow is formed in the hole. The bias of the fuel flow in the slit-shaped nozzle hole biases the fuel spray to be injected as a result, so that it is possible to control the shape, injection direction, etc. of the fuel spray to be injected according to the operating state.

  According to a second aspect of the invention, in the first aspect of the invention, the higher the in-cylinder pressure during fuel injection, the more the plate-like member flows along the plate-like member surface with respect to the rotation shaft. An in-cylinder injection spark ignition internal combustion engine that controls the rotational position of the plate member so that the direction of fuel flow along the plate member surface is parallel to the injection center axis of the injection hole. Is provided.

  That is, in the invention according to claim 2, the fuel flow control valve is controlled such that the higher the in-cylinder pressure at the time of fuel injection, the closer the fuel flow direction along the plate-like member surface is parallel to the injection center axis of the injection hole. By doing so, the amount of separation of the fuel flow along the surface of the plate member in the vicinity of the rotating shaft, which is the downstream end of the fuel flow control valve, is reduced. If the amount of separation is small, the fuel flow that flows in and flows in the direction of the side wall surface, and the flow velocity of the fuel flow flowing in the vicinity of the side wall surface is less attenuated, compared to a conventional fuel injection valve that does not have a fuel flow control valve. The flow velocity becomes faster and the contraction is suppressed. That is, by increasing the flow velocity of the fuel flow that flows in the vicinity of the side wall surface that forms the outer portion of the fuel spray, it becomes possible for the fuel spray to go straight against the force trying to draw the outer fuel spray inward. As a result, contraction is suppressed.

  According to a third aspect of the present invention, in the second aspect of the present invention, the plate-like members of the two fuel flow control valves are controlled to different rotational positions so that the fuel flow is within the slit-like nozzle hole. There is provided an in-cylinder injection spark ignition internal combustion engine that flows in a biased manner.

  That is, in the invention according to claim 3, by controlling the plate-like members of the two fuel flow control valves to different rotational positions, the fuel flow flowing into the slit-like nozzle is biased, and as a result, the injection is performed. The fuel spray is also injected unevenly. As a result, a swirl can be formed in the combustion chamber and can be strengthened.

  According to a fourth aspect of the invention, in the first aspect of the invention, the plate-like member is disposed on the downstream side of the fuel flow along the plate-like member surface with respect to the rotating shaft, and the plate-like member is provided. An in-cylinder spark-ignition internal combustion engine is provided that controls the rotational position of the plate member so that the direction of fuel flow along the surface of the member faces the injection center axis direction of the injection hole.

  That is, in the invention described in claim 4, the slit-shaped nozzle hole is controlled by controlling the rotation position of the plate-shaped member so that the fuel flow direction along the surface of the plate-shaped member faces the injection center axis direction of the nozzle hole. The fuel flow is concentrated in the vicinity of the injection center axis of the inner nozzle hole, and as a result, the fuel spray to be injected also has a fan shape with a small central angle. Therefore, the penetration force of the fuel spray is increased, and the tumble can be formed and strengthened.

  According to the invention described in each claim, in a cylinder injection type spark ignition internal combustion engine having a slit injection hole and a fuel injection valve that forms a fan-shaped fuel spray in a combustion chamber, the internal combustion engine is responsive to the operating state of the engine. The fuel spray can be controlled in common.

  A cylinder injection spark ignition internal combustion engine according to the present invention will be described with reference to FIG. In FIG. 1, 1 is an engine body having four cylinders, for example, 2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is an intake valve, 7 is an intake passage, 8 is an exhaust valve, Reference numeral 9 denotes an exhaust passage, and 10 denotes a spark plug. The intake passage 7 is connected to a surge tank 12 via a corresponding intake branch pipe 11, and the surge tank 12 is connected to an air cleaner 14 via an intake duct 13. An air flow meter 15 for detecting the intake air flow rate and a throttle valve 17 driven by a step motor 16 are arranged in the intake duct 13. Further, an electrically controlled fuel injection valve 18 for injecting fuel into the combustion chamber 5 is disposed in the combustion chamber 5.

  On the other hand, the exhaust passage 9 is connected to a small capacity three-way catalyst 20 through an exhaust branch pipe 19. A water temperature sensor 21 for detecting the engine cooling water temperature is attached to the engine body 1, and an in-cylinder pressure sensor 22 for detecting the cylinder internal pressure of the combustion chamber 5 is attached to the cylinder head 3.

  The electronic control unit (ECU) 40 is a digital computer and includes a ROM (read only memory) 42, a RAM (random access memory) 43, a CPU (microprocessor) 44, an input port 45, An output port 46 is provided. The accelerator pedal 49 is connected to a load sensor 50 for detecting the depression amount of the accelerator pedal 49. Here, the depression amount of the accelerator pedal 49 represents a required load.

  Output signals of the air flow meter 15, the water temperature sensor 21, the in-cylinder pressure sensor 22, and the load sensor 50 are input to the input port 45 via the corresponding AD converters 47. Further, the input port 45 is connected to a crank angle sensor 51 that generates an output pulse every time the crankshaft rotates, for example, 30 °. The CPU 44 calculates the engine speed based on the output pulse of the crank angle sensor 51. On the other hand, the output port 46 is connected to the spark plug 10, the step motor 16, and the fuel injection valve 18 via the corresponding drive circuit 48, and these are controlled based on the output signal from the electronic control unit 40.

  FIG. 2 is a schematic longitudinal sectional view of the tip portion of the fuel injection valve 18. In FIG. 2, 25 is a needle valve, 26 is an injection valve main body, 27 is a sack portion formed by a spherical wall surface 27a, 28 is a slit-shaped nozzle hole formed in a slit shape, and 30 flows into the slit-shaped nozzle hole 28. 1 shows a fuel flow control valve for controlling the direction of fuel flow. Next, the fuel flow control valve 30 will be described with reference to FIGS.

  3 shows a cross-sectional view taken along line AA in FIG. 2, and FIG. 4 shows an inlet portion of the slit-like nozzle hole 28 viewed from the direction of the sack portion 27. FIG. The fuel flow control valve 30 is formed in the vicinity of the nozzle hole inlet edge on the two side wall surfaces 28a side in the slit-shaped nozzle hole 28 that regulates the expansion of the fan-shaped central angle α formed by the fuel spray. The rotary shaft 30a is fixed in parallel, and has a plate-like member 30b that is connected to the rotary shaft 30a and is rotatable about the rotary shaft. Be controlled. The output port 46 is also connected to the actuator of the fuel flow control valve 30 via a corresponding drive circuit 48 and is controlled based on an output signal from the electronic control unit 40. As shown in FIG. 3, the rotation position of the plate-like member 30b is defined as an angle formed by the plane of the plate-like member 30b and the side wall surface 28a including the edge where the plate-like member 30b is disposed. The separation angle θ is controlled stepwise or steplessly by the actuator.

  The rotation position of the plate member 30b is such that the peel angle θ at which the tip of the plate member 30b contacts the spherical wall surface 27a of the sack portion 27 is the maximum θmax, and the peel angle θ is zero, that is, the plane of the plate member 30b Control is performed between the positions where the side wall surface 28a and the side surface 28a become the same surface, but in some cases, the separation angle θ can be controlled in the negative direction, for example, so that the plate-like member 30b enters the slit-like nozzle hole 28. It is.

  By the way, as described above, the contracted flow has a low pressure inside the fuel spray (that is, fuel spray injected by the fuel flow in the vicinity of the injection center axis X of the nozzle hole), and the outside of the fuel spray (that is, the side wall surface). When the pressure of the fuel spray injected by the fuel flow in the vicinity of 28a is high, the fuel spray is drawn inward and contracted due to the pressure difference. Therefore, the contracted flow is likely to occur under a situation where the in-cylinder pressure is high such that the pressure difference becomes large because the pressure outside the fuel spray is high.

  Therefore, in the present invention, the fuel flow control valve 30 is used to increase the flow rate of the fuel spray in the vicinity of the side wall surface 28a, that is, to increase the flow velocity of the fuel flow. So that the contraction is suppressed. Hereinafter, a method for increasing the flow velocity of the fuel flow in the vicinity of the side wall surface 28a will be described.

  5 and 6 are cross-sectional views taken along the line AA of FIG. 2 which is the same as FIG. 3. In the drawing, arrows extending from the sack portion 27 into the slit-like injection holes 28 indicate the flow of fuel. First, FIG. 5 shows the rotational position of the plate-like member 30b under a low in-cylinder pressure. Under a situation where the in-cylinder pressure is low, the pressure difference between the inside and outside of the fuel spray as described above is small, and the contracted flow hardly occurs. Therefore, the rotation position of the plate-like member 30b is made uniform so that the fuel spray injected from the vicinity of the injection center axis X of the injection hole and the outer side wall surface 28a is uniform, so that the peeling angle θ is increased. For example, the fuel flow control valve 30 is controlled so that the tip of the fuel flow control valve 30 has a separation angle θmax that comes into contact with the spherical wall surface 27 a of the sack portion 27. In this case, as shown in FIG. 5, the fuel flow in the vicinity of the side wall surface 28 a is formed by the fuel flow separated at the downstream end of the fuel flow control valve 30 wrapping around in the side wall surface direction.

  On the other hand, FIG. 6 shows the rotational position of the plate-like member 30b under a high cylinder pressure. Under the situation where the in-cylinder pressure is high, the contracted flow occurs as described above. Therefore, the rotation position of the plate-like member 30b is controlled so that the peeling angle θ becomes smaller. That is, when the separation angle θ is small, the amount of wraparound of the separated fuel flow that forms the fuel flow in the vicinity of the side wall surface 28a is small, and the flow velocity is less attenuated than when the separation angle θ is large. Therefore, when the separation angle θ is small, the flow velocity of the fuel flow in the vicinity of the side wall surface 28a is faster than when the separation angle θ is large, and the outer fuel spray injected by the fuel flow tends to be drawn inward. Therefore, it is possible to go straight against the force, and the contraction can be suppressed.

  FIG. 7 is a diagram showing the relationship between the fuel injection timing during the compression stroke and the separation angle θ. Referring to FIG. 7, as the fuel injection timing becomes the compression top dead center (TDC) side, that is, the retard angle side, the separation angle θ is set smaller. This is because the in-cylinder pressure becomes higher as the fuel injection timing is retarded, so that the contracted flow is likely to occur. Therefore, the flow rate in the vicinity of the side wall surface 28a is increased by increasing the peeling angle θ. In this case, the peel angle θ is never smaller than θmin, and the peel angle θmin is determined so that the density of the fuel inside the fuel spray does not become too thin. On the other hand, the compression bottom dead center (BDC) side of the fuel injection timing is naturally not larger than the separation angle θmax. The relationship shown in FIG. 7 is obtained in advance by experiment or calculation and stored in the ROM 42.

  FIG. 8 shows the relationship between the fuel injection timing and the separation angle θ that change according to the change in the in-cylinder pressure due to the change in the intake air amount that has changed due to the opening of the throttle valve 17 and the introduction of the exhaust gas recirculation gas. FIG. This considers factors other than the fuel injection timing shown in FIG. 7 as a factor for changing the in-cylinder pressure, and determines the separation angle θ according to the in-cylinder pressure and the fuel injection timing. The lower the in-cylinder pressure, the larger the absolute value of the slope of the straight line indicating the relationship between the fuel injection timing and the separation angle θ. The relationship shown in FIG. 8 is obtained in advance by experiment or calculation and stored in the ROM 42.

  9 is a cross-sectional view taken along line AA in FIG. 2 which is the same as FIG. 3, and shows an embodiment in which the fuel flow control valve 30 is applied. According to the embodiment shown in FIG. 9, the separation angle θ of one of the two plate-like members 30b (for example, the separation angle θ of the left fuel flow control valve 30 in FIG. 9) is smaller than the other. By doing so, it is possible to bias the fuel flow within the slit-shaped injection hole 28, and as a result, it is possible to deflect the injected fuel spray to one side. FIG. 10 is a schematic view showing the spread of the fuel spray in the combustion chamber as seen from the top of the combustion chamber, showing the deflected fuel spray 35 injected by the embodiment shown in FIG. Thus, by deflecting the fuel spray 35, it is possible to form the swirl S in the combustion chamber 5 as shown by the arrow and strengthen it. The relationship between the different peel angles θ of the two plate-like members 30b and the strength of the swirl is obtained in advance by experiment or calculation and stored in the ROM 42.

  11 is a cross-sectional view taken along line AA in FIG. 2 which is the same as FIG. 3, and shows another embodiment to which the fuel flow control valve 30 is applied. According to the embodiment shown in FIG. 11, both the plate-like members 30 b of the two fuel flow control valves 30 are controlled to enter the slit-like injection holes 28. That is, the plate-like shape is in a rotational position where the peel angle θ is a negative value and the fuel flow flows along the front surface (that is, the back surface) of the plate-like member 30b different from the other embodiments described above. The member 30b is controlled. By arranging the plate-like member 30b in this manner, the fan-shaped central angle α of the fuel spray 35 is small, and the fuel flow is concentrated in the vicinity of the injection center axis X of the nozzle hole, thereby increasing the penetration force of the fuel spray. FIG. 12 is a schematic view showing the spread of fuel spray in the combustion chamber as seen from the top of the combustion chamber, showing the fuel spray 35 concentrated in the vicinity of the injection center axis X of the injection hole injected by the embodiment shown in FIG. It shows that the penetrating power is increasing. Thus, by concentrating the fuel spray 35, it is possible to form a tumble and strengthen it. The relationship between the peel angle θ and the strength of the tumble is obtained in advance by experiment or calculation and stored in the ROM 42.

1 is an overall view of a direct injection spark ignition internal combustion engine. It is a schematic longitudinal cross-sectional view of the front-end | tip part of a fuel injection valve. It is sectional drawing in line AA of FIG. The entrance part of the slit-shaped nozzle hole seen from the sack part direction is shown. It is sectional drawing in line AA of FIG. 2, and is a figure which shows arrangement | positioning of the fuel flow control valve under a low cylinder pressure. It is sectional drawing in line AA of FIG. 2, and is a figure which shows arrangement | positioning of the fuel flow control valve under high cylinder pressure. It is a figure which shows the relationship between a fuel-injection time and a peeling angle. It is a figure which shows the relationship between the fuel injection timing according to the change of a cylinder pressure, and a peeling angle. It is sectional drawing in line AA of FIG. 2, and shows embodiment which applied the fuel flow control valve. FIG. 10 is a schematic view showing the spread of fuel spray in the combustion chamber as viewed from the top of the combustion chamber in the embodiment shown in FIG. 9. It is sectional drawing in line AA of FIG. 2, and shows embodiment which applied the fuel flow control valve. FIG. 12 is a schematic view showing the spread of fuel spray in the combustion chamber as viewed from the top of the combustion chamber in the embodiment shown in FIG. 11. It is the schematic which shows the breadth of the fuel spray in a combustion chamber seen from the combustion chamber top part for showing the contracted flow by the conventional fuel injection valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 18 Fuel injection valve 27 Sack part 28 Slit-shaped injection hole 28a Side wall surface 30 Fuel flow control valve 30a Rotating shaft 30b Plate-shaped member

Claims (4)

  In a cylinder-injection spark ignition internal combustion engine equipped with a fuel injection valve that has a slit-shaped nozzle hole and forms a flat fan-shaped fuel spray in the combustion chamber, a slit-shaped jet that regulates the spread of the central angle of the fan-shaped fuel spray A rotating shaft fixed in parallel with the nozzle hole inlet edge in the vicinity of the nozzle hole inlet edge on the two side wall surfaces in the hole, and one end connected to the rotating shaft and rotatable about the rotating shaft A fuel flow control valve having a plate-like member is disposed, and during fuel injection, the rotational position of the plate-like member is controlled, and the fuel flow along the plate-like member surface is directed to the injection center axis of the nozzle hole. An in-cylinder spark-ignition internal combustion engine that flows into a slit-shaped injection hole while being deflected.   The higher the in-cylinder pressure at the time of fuel injection, the more the plate-like member is arranged on the upstream side of the fuel flow along the plate-like member surface with respect to the rotating shaft, and the direction of the fuel flow along the plate-like member surface is the injection hole The in-cylinder injection spark ignition internal combustion engine according to claim 1, wherein the rotational position of the plate-like member is controlled so as to approach parallel to the injection center axis.   3. The direct injection spark ignition internal combustion engine according to claim 2, wherein the plate-like members of the two fuel flow control valves are controlled to different rotational positions so that the fuel flow is biased into the slit-like injection holes.   The plate-like member is disposed on the downstream side of the fuel flow along the plate-like member surface with respect to the rotation axis, and the direction of the fuel flow along the plate-like member surface is directed to the injection center axis direction of the injection hole. The in-cylinder spark-ignition internal combustion engine according to claim 1, wherein the rotational position of the plate member is controlled.

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