JP2006257992A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve combustion stability, by suppressing variation in fuel spray, in a fuel injection device. <P>SOLUTION: A fuel passage 51 is disposed in a housing 41, a suck part 44 communicating with the fuel passage 51 and an injection port 45 are formed at a tip part thereof, a needle valve 46 is movably supported by the housing 41 to open/close the fuel passage 51, and the injection port 45 is inclined upward at a predetermined angle to set an injection angle α. A spray angle β is set to be in a fan-like form widened from side to side to disperse the fuel spray to the side to side, the length La of a first injection passage 45a on a center axis O<SB>2</SB>side of the injection port 45 is set to be shorter than the length Lb of a second injection passage 45b on a side opposite to the injection axis O<SB>1</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection device capable of injecting a predetermined amount of fuel.

  2. Description of the Related Art Conventionally, a direct injection internal combustion engine that directly injects fuel into a combustion chamber instead of an intake port is known. In this cylinder injection internal combustion engine, when the intake valve is opened and closed, air is drawn into the combustion chamber from the intake port and compressed by the piston, and fuel is directly injected from the fuel injection valve to the high-pressure air. Then, high-pressure air and mist-like fuel are mixed in the combustion chamber, the mixture is led to the ignition plug, ignites and explodes, and the exhaust gas is discharged from the intake port when the exhaust valve is opened and closed. .

  In such an in-cylinder injection internal combustion engine, the fuel injection device is energized and supported so that the needle valve is movable and the fuel passage is closed in a housing having a sac portion and an injection port at the tip. Has been configured. Then, by moving the needle valve at a predetermined timing to open the fuel passage, the fuel in the fuel passage is injected from the injection port toward the combustion chamber through the sac portion. As such a fuel injection device, there is one described in Patent Document 1 below.

Japanese Patent Application Laid-Open No. 9-126095

  By the way, when the fuel in the sac portion is injected into the combustion chamber through the injection port in the fuel injection device of the cylinder injection type internal combustion engine, the cavitation bubbles generated in the injection port are immediately disappeared. However, there is a problem that a homogeneous air-fuel mixture cannot be formed in the combustion chamber.

  FIG. 9 is a longitudinal sectional view of a tip portion of a conventional fuel injection device, FIG. 10 is a sectional view taken along line XX of FIG. 9, and FIG. 11 is a schematic diagram showing a cavitation generation state at an injection port of the conventional fuel injection device. FIG.

In the conventional fuel injection device, as shown in FIGS. 9 and 10, a sac portion 002 and an injection port 003 are formed at the front end of a housing 001, and a needle valve 004 is movably supported in the housing 001. The passage 005 can be opened and closed. In this case, the injection port 003 has a fan shape with a wide angle to the left and right, and the injection angle α is set by inclining the injection axis O ₁ upward by a predetermined angle with respect to the axis O ₂ of the needle valve 004. Accordingly, by moving the needle valve 004 to open the fuel passage 005, the fuel in the fuel passage 005 is injected from the injection port 003 via the sac portion 002.

  When the fuel of the sac portion 002 is injected outside through the injection port 003, the fuel is sucked from the sack portion 002 to the injection port 003 so that the fuel of the sac portion 002 hardly flows to the injection port 003. Cavitation occurs on the inner surface of the injection port 003. Since the injection angle α is set at the injection port 003, the fuel hardly flows from the sack portion 002 to the upper surface 003a side of the injection port 003, and the separation portion E is generated here, while the lower surface 003b of the injection port 003 is generated. Cavitation C occurs on the side. This cavitation has a large number of bubbles, and the fuel can be atomized by the bursting of the bubbles. However, since the bubbles contained in the fuel burst and disappear in the injection port 003, Atomization cannot be performed sufficiently. For this reason, a high-quality air-fuel mixture cannot be formed in the combustion chamber, and combustion becomes unstable, resulting in deterioration of fuel consumption and output.

  The present invention is for solving such a problem, and an object of the present invention is to provide a fuel injection device that improves combustion stability by suppressing fluctuations in fuel spray.

  In order to solve the above-described problems and achieve the object, a fuel injection device of the present invention includes a housing having a fuel passage and a sac portion and an injection port that communicate with the fuel passage at a tip portion, and the housing moves to the housing. An injection valve that is freely supported and capable of intermittently connecting and disconnecting the fuel passage, wherein the injection axis is inclined at a predetermined angle with respect to the injection axis; The length of the first injection passage on the side is set shorter than the length of the second injection passage on the side opposite to the injection valve axis at the injection port.

  The fuel injection device according to the present invention is characterized in that the injection port is formed in a fan shape with left and right wide angles, and is inclined upward by a predetermined angle with respect to the axis of the injection valve.

  In the fuel injection device of the present invention, the length of the first injection passage is set to about ½ of the length of the second injection passage.

  The fuel injection device of the present invention is characterized in that a curved surface portion is formed at a downstream end portion of the first injection passage in the fuel injection direction.

  In the fuel injection device according to the present invention, a curved surface portion is formed between the upstream end portion in the fuel injection direction in the second injection passage and the sac portion.

  According to the fuel injection device of the present invention, the fuel passage is provided in the housing, the sac portion and the injection port are provided at the tip, the injection valve is movably supported in the housing, and the fuel passage can be intermittently connected. Is formed so as to be inclined at a predetermined angle with respect to the injection valve axis, and the length of the first injection passage on the injection valve axis side in the injection port is set to the length of the second injection passage on the side opposite to the injection valve axis in the injection port. Therefore, when the fuel in the sack portion is injected into the combustion chamber through the injection port, separation of the injected fuel occurs on the second injection passage side, while cavitation occurs on the first injection passage side. However, since the length of the first injection passage is set to be short, the generated cavitation bubbles flow well without being ruptured here, and ruptured when injected into the combustion chamber from the injection port. Atomize Can be injected into the combustion chamber in the state, by forming a high-quality mixture into the combustion chamber and safe atomization of fuel spray, it is possible to improve the combustion stability.

  Embodiments of a fuel injection device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  1 is a longitudinal sectional view of a main part showing a fuel injection device according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II in FIG. 1, and FIG. 3 is an injection port of the fuel injection device according to the first embodiment. FIG. 4 is a schematic diagram showing the cavitation generation state in FIG. 4, FIG. 4 is a graph showing the particle size of the fuel spray with respect to the distance in the width direction of the injection port of the fuel injection device of the first embodiment, and FIG. 1 is a schematic configuration diagram of an internal combustion engine to which is applied.

  In the internal combustion engine to which the fuel injection device of the first embodiment is applied, as shown in FIG. 5, the engine 10 is a cylinder injection type spark ignition engine. In this engine 10, a cylinder head 12 is fastened on a cylinder block 11, and pistons 14 are fitted to a plurality of cylinder bores 13 formed in the cylinder block 11 so as to freely move up and down. A crankshaft 15 is rotatably supported at the lower portion of the cylinder block 11, and the pistons 14 are connected to the crankshaft 15 via connecting rods 16, respectively.

  The combustion chamber 17 is composed of a cylinder block 11, a cylinder head 12, and a piston 14. The combustion chamber 17 has a pent roof shape that is inclined so that the central portion of the upper portion (the lower surface of the cylinder head 12) is raised. Yes. An intake port 18 and an exhaust port 19 are formed on the upper portion of the combustion chamber 17, that is, the lower surface of the cylinder head 12, and the intake valve 20 and the exhaust valve 19 are opposed to the intake port 18 and the exhaust port 19. The lower end portions of 21 are located respectively. Accordingly, when the intake valve 20 and the exhaust valve 21 move up and down at a predetermined timing, the intake port 18 and the exhaust port 19 are opened and closed, and the intake port 18 and the combustion chamber 17, and the combustion chamber 17 and the exhaust port 19 are respectively connected. You can communicate.

  A surge tank 23 is connected to the intake port 18 via an intake manifold 22, and an intake pipe 24 is connected to the surge tank 23, and an air cleaner 25 is attached to an air intake port of the intake pipe 24. Yes. An electronic throttle device 26 having a throttle valve is provided on the downstream side of the air cleaner 25. The cylinder head 12 is provided with an injector 27 that injects fuel directly into the combustion chamber 17. The injector 27 is located on the intake port 18 side and is inclined at a predetermined angle in the vertical direction. Further, the cylinder head 12 is provided with a spark plug 28 that is located above the combustion chamber 17 and ignites the air-fuel mixture.

  On the other hand, an exhaust pipe 30 is connected to the exhaust port 19 via an exhaust manifold 29. The exhaust pipe 30 is a catalyst device that purifies harmful substances such as HC, CO, and NOx contained in the exhaust gas. 31 and 32 are mounted. Further, an exhaust gas recirculation passage (EGR passage) 33 is provided between the downstream side of the surge tank 23 in the intake pipe 24 and between the catalyst devices 31 and 32 in the exhaust pipe 30. Is provided with an EGR valve 34.

  In addition, an electronic control unit (ECU) 35 is mounted on the vehicle, and the ECU 35 can control the injector 27, the spark plug 28, the EGR valve 34, and the like. That is, an air flow sensor 36 is mounted on the upstream side of the intake pipe 24, and an intake negative pressure sensor 37 is mounted on the surge tank 23, and the measured intake air amount and intake negative pressure are output to the ECU 35. Further, the electronic throttle device 26 outputs the current throttle opening degree to the ECU 35, and the engine speed sensor 38 outputs the detected engine speed to the ECU 35. Therefore, the ECU 35 determines the fuel injection amount, the injection timing, the ignition timing, the EGR valve opening, based on the detected engine operation state such as the intake air amount, intake negative pressure, throttle opening (or accelerator opening), and engine speed. The degree is determined.

  In the injector 27 mounted on the engine 10 thus configured, as shown in FIGS. 1 and 2, the housing 41 has a hollow cylindrical shape, and the distal end portion 43 has a small diameter with respect to the main body portion 42. A sack portion 44 having a spherical shape is formed at the distal end portion 43, and an injection port 45 opening to the outside is formed. A needle valve 46 as an injection valve is configured such that a cylindrical valve body 48 integrally extends downward from a disk-shaped flange portion 47, and the outer peripheral surface of the flange portion 47 is the inner side of the body portion 42 in the housing 41. It is fitted to the peripheral surface and supported so as to be movable along the axial direction (vertical direction in FIG. 1). In addition, the needle valve 46 has an outer peripheral surface of the valve body 48 inserted into the inner peripheral surface of the distal end portion 43 of the housing 41 with a predetermined gap, and a conical distal end surface 49 abuts against the inclined surface 50 of the distal end portion 43. Here, a seal portion is formed.

  Therefore, the fuel passage 51 is formed between the housing 41 and the needle valve 46, and the lower end side of the fuel passage 51 can communicate with the injection port 45 via the sack portion 44. The fuel passage 51 can be blocked by the tip surface 49 of the needle valve 46 coming into contact with the inclined surface 50 of the housing 41, while the fuel passage 51 is opened when the tip surface 49 moves away from the inclined surface 50. The fuel in the fuel passage 51 can be injected to the outside from the injection port 45 via the sac portion 44.

  A support plate 53 is fixed in the housing 41 via a support ring 52, and a coil spring 54 is interposed between the support plate 53 and the needle valve 46 in a compressed state. Therefore, the needle valve 46 is urged in a direction in which the tip surface 49 comes into close contact with the inclined surface 50 of the housing 41 by the urging force of the coil spring 54 and blocks the fuel passage 51. On the other hand, a solenoid 55 is built in the wall of the housing 41 so as to face the flange portion 47 of the needle valve 46 and be positioned slightly above. Accordingly, when the solenoid 55 is energized, a suction force is generated, and the needle valve 46 is moved upward against the urging force of the spring 54 to open the fuel passage 51.

  A fuel pump, a fuel tank, and the like are connected to the base end portion of the injector 27 via a delivery pipe (not shown), and fuel of a predetermined pressure is supplied to the upstream side of the fuel passage 51 through the housing 41. .

By the way, in this embodiment, the injector 27 is mounted on the intake port 18 side, is inclined at a predetermined angle from the vertical state to the exhaust port 19 side, and the injection port 45 has an injection axis (injection port axis) O ₁ at the injector. The injection angle α is set by inclining upward by a predetermined angle with respect to 27 central axis (injection valve axis) O ₂ . Further, the injection port 45 is formed in a fan shape that is wide-angled left and right so that the fuel spray injected from the injection port 45 diffuses left and right, and the spray angle β is set.

In this injection port 45, the length La of the first injection passage 45 a on the central axis O ₂ side of the injection port 45, that is, the upper surface side in FIG. ₁ is opposite to the injection axis O ₁ , that is, the lower surface. The length is set shorter than the length Lb of the second injection passage 45b on the side. That is, the lower outer peripheral surface 43b on the side where the injection port 45 is formed (the right side in FIG. 1) is formed in a spherical shape with the center O of the sack portion 44 as a fulcrum at the tip portion 43 of the housing 41, The lower outer peripheral surface 43a on the side where the opening 45 is not formed (left side in FIG. 1) is formed in a spherical shape having a fulcrum (not shown) slightly above the center O of the sack portion 44, and the lower outer periphery of the tip portion 43 By forming the surface so that a step is formed at the position of the injection port 45, the length La of the first injection passage 45a and the length Lb of the second injection passage 45b are made different. In this case, the length La of the first injection passage 45a is preferably set to about ½ of the length Lb of the second injection passage 45b. A section Lc in which the first injection passage 45a does not exist with respect to the second injection passage 45b is set as a fuel spray run-up section.

  Therefore, as shown in FIG. 1, when the solenoid valve 55 is energized from the state in which the needle valve 46 closes the fuel passage 51 by the biasing force of the coil spring 54 in the injector 27, the needle valve 46 moves to the coil spring 54. By moving upward against the urging force, the fuel passage 51 is opened, and the fuel in the fuel passage 51 is supplied to the sac portion 44 and is injected from the sac portion 44 into the combustion chamber 17 through the injection port 45. When the predetermined period has elapsed, the energization of the solenoid 55 is stopped, and the needle valve 46 is moved downward by the urging force of the coil spring 54 to close the fuel passage 51, and the fuel passage 51 is connected to the sack portion 44. Fuel supply is stopped, and fuel injection from the injection port 45 ends.

  When the fuel is injected by the injector 27, as shown in FIG. 3, when the fuel supplied from the fuel passage 51 to the sac portion 44 flows into the injection port 45, the sac portion 44 enters the first injection passage 45a of the injection port 45. The fuel Fb flowing from the sack portion 44 into the second injection passage 45b of the injection port 45 is less likely to flow than the fuel Fa flowing in, so that the injection fuel peeling E occurs on the second injection passage 45b side, Cavitation C occurs on the side of one injection passage 45a. In this case, in this embodiment, since the length La of the first injection passage 45a at the injection port 45 is set shorter than the length Lb of the second injection passage 45b, the generated cavitation bubbles are generated in the first injection passage 45a. Then, the gas flows well without being ruptured, and the pressure is released in the running section Lc from the injection port 45 to the combustion chamber 17 so that the bubbles are injected while being ruptured. Therefore, the fuel spray is properly atomized by the burst of cavitation bubbles, and is injected into the combustion chamber 17 in the atomized state, and a high-quality air-fuel mixture is formed in the combustion chamber 17. Is done.

  Incidentally, in the injection port 45, the length La of the first injection passage 45a is set to about ½ of the length Lb of the second injection passage 45b. Is set. That is, in this embodiment, when the injection angle α is 20 degrees, the relationship La = (1/2) Lb is established. FIG. 4 is a graph showing the particle size of the fuel spray with respect to the position in the width direction of the injection port 45. The relationship between the length La of the first injection passage 45a and the length Lb of the second injection passage 45b is expressed as La = Lb. , La = (1/2) Lb, La = (1/3) Lb, and La = (1/4) Lb. As shown in the graph of FIG. 4, when the relationship between the length La of the first injection passage 45a and the length Lb of the second injection passage 45b is La = (1/2) Lb, the spray particle size is the smallest. You can see that As the injection angle α increases, the length La of the first injection passage 45a may be set shorter than the length Lb of the second injection passage 45b.

As described above, in the fuel injection device according to the first embodiment, the fuel passage 51 is provided in the housing 41, and the sack portion 44 and the injection port 45 communicating with the fuel passage 51 are formed at the front end portion. The needle valve 46 is movably supported so that the fuel passage 51 can be opened and closed, and the injection angle 45 is set by tilting the injection port 45 upward by a predetermined angle, and the left and right sides of the fuel spray are diffused so that the fuel spray spreads to the left and right. A spray angle β formed in a wide-angle fan shape is set, and the length La of the first injection passage 45a on the central axis O ₂ side in the injection port 45 is set to the length of the second injection passage 45b on the side opposite to the injection axis O _1. The length is set shorter than Lb.

  Accordingly, when the fuel in the sack portion 44 is injected into the combustion chamber 17 through the injection port 45, the fuel E is separated on the second injection passage 45b side, while the cavitation C is generated on the first injection passage 45a side. Although generated, the length of the first injection passage 45a is set to be short, so that the generated cavitation bubbles flow well without rupturing here, and rupture when injected into the combustion chamber 17 from the injection port 45. In this way, the fuel can be injected into the combustion chamber in the atomized state, and the combustion stability can be improved by reliably atomizing the fuel spray and forming a good mixture in the combustion chamber. Can do.

  FIG. 6 is a longitudinal sectional view of a main part showing a fuel injection device according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

In the fuel injection apparatus according to the second embodiment, as shown in FIG. 6, the injection port 45 of the injector 27 is such that the injection axis O ₁ is inclined upward by a predetermined angle with respect to the central axis O _{2 of the} injector 27. α is set. In this injection port 45, the length La of the first injection passage 45 a on the central axis O ₂ side of the injection port 45, that is, the upper surface side in FIG. ₁ is opposite to the injection axis O ₁ , that is, the lower surface. The length is set shorter than the length Lb of the second injection passage 45b on the side. That is, at the distal end 43 of the housing 41, to form a lower outer peripheral surface into a spherical shape with the fulcrum center O of the sac portion 44, the opening scraped off a central axis O ₂ side of the injector 27 in the injection port 45 61 Thus, the length La of the first injection passage 45a and the length Lb of the second injection passage 45b are made different from each other. In this case, the length La of the first injection passage 45a is preferably set to about ½ of the length Lb of the second injection passage 45b. A section Lc in which the first injection passage 45a does not exist with respect to the second injection passage 45b is set as a fuel spray run-up section.

  Accordingly, when the needle valve 46 moves upward in the injector 27 to open the fuel passage 51, the fuel in the fuel passage 51 is supplied to the sac portion 44, and the combustion chamber 17 is supplied from the sack portion 44 through the injection port 45. Is injected into. At the time of fuel injection by the injector 27, separation of the injected fuel occurs on the second injection passage 45b side, while cavitation occurs on the first injection passage 45a side. In this case, in this embodiment, since the length La of the first injection passage 45a at the injection port 45 is set shorter than the length Lb of the second injection passage 45b, the generated cavitation bubbles are generated in the first injection passage 45a. Then, the gas flows well without being ruptured, and the pressure is released in the run-up section Lc from the injection port 45 to the combustion chamber 17 so that the bubbles are injected while being ruptured. Therefore, the fuel spray is properly atomized by the burst of cavitation bubbles, and is injected into the combustion chamber 17 in the atomized state, and a high-quality air-fuel mixture is formed in the combustion chamber 17. Is done.

Thus, in the fuel injection device of the second embodiment, the injection angle α is set by inclining the injection port 45 upward by a predetermined angle, and the first injection passage 45a on the central axis O ₂ side in the injection port 45 is set. the length La, is set shorter than the length Lb of the second injection passage 45b on the side opposite to the injection axis O _1. Accordingly, when the fuel in the sac portion 44 is injected into the combustion chamber 17 through the injection port 45, cavitation C is generated on the first injection passage 45a side, but the length of the first injection passage 45a is set to be short. Therefore, when the generated cavitation bubbles are injected into the combustion chamber 17 without being ruptured in the first injection passage 45a, the fuel can be injected into the combustion chamber in the atomized state, and the combustion is performed. Combustion stability can be improved by forming a high-quality air-fuel mixture in the chamber.

In the second embodiment, the opening 61 is formed by scraping the central axis O ₂ side of the injector 27 at the injection port 45, so that the length La of the first injection passage 45a is the length of the second injection passage 45b. It is set shorter than Lb. Accordingly, the length La of the first injection passage 45a can be shortened without significantly changing the shape of the distal end portion 43 of the housing 41, and an increase in manufacturing cost can be suppressed.

  FIG. 7 is a longitudinal sectional view of a main part showing a fuel injection device according to Embodiment 3 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

In the fuel injection device according to the third embodiment, as shown in FIG. 7, the injection port 45 of the injector 27 is such that the injection axis O ₁ is inclined upward by a predetermined angle with respect to the central axis O _{2 of the} injector 27. α is set. In this injection port 45, the length La of the first injection passage 45a on the central axis O ₂ side in this injection port 45, that is, the upper surface side in FIG. 7, is opposite to the injection axis O ₁ , that is, the lower surface. The length is set shorter than the length Lb of the second injection passage 45b on the side. That is, at the distal end 43 of the housing 41, to form a lower outer peripheral surface into a spherical shape with the fulcrum center O of the sac portion 44, the opening scraped off a central axis O ₂ side of the injector 27 in the injection port 45 61 Is formed such that the length La of the first injection passage 45a and the length Lb of the second injection passage 45b are different, and the curved surface portion 62 is formed at the downstream end portion of the first injection passage 45a in the fuel injection direction. is doing. In this case, the length La of the first injection passage 45a is preferably set to about ½ of the length Lb of the second injection passage 45b. A section Lc in which the first injection passage 45a does not exist with respect to the second injection passage 45b is set as a fuel spray run-up section.

  Accordingly, when the needle valve 46 moves upward in the injector 27 to open the fuel passage 51, the fuel in the fuel passage 51 is supplied to the sac portion 44, and the combustion chamber 17 is supplied from the sack portion 44 through the injection port 45. Is injected into. At the time of fuel injection by the injector 27, separation of the injected fuel occurs on the second injection passage 45b side, while cavitation occurs on the first injection passage 45a side. In this case, in this embodiment, since the length La of the first injection passage 45a at the injection port 45 is set shorter than the length Lb of the second injection passage 45b, the generated cavitation bubbles are generated in the first injection passage 45a. Then it flows well without bursting. In addition, since the curved surface portion 62 is formed at the downstream end portion of the first injection passage 45a in the fuel injection direction, the bubbles of fuel in the injection port 45 reach the curved surface portion 62 from the first injection passage 45a. The pressure is released, the bubbles burst, and the atomized fuel spray flows along the curved surface portion 62 and is injected. Therefore, the fuel spray is appropriately atomized by the burst of cavitation bubbles, and is injected into the combustion chamber 17 in the atomized state, and a high-quality air-fuel mixture is formed in the combustion chamber 17. Is done.

Thus, in the fuel injection device of the third embodiment, the injection angle α is set by inclining the injection port 45 upward by a predetermined angle, and the first injection passage 45a on the central axis O ₂ side in the injection port 45 is set. the length La, as well as shorter than the length Lb of the second injection passage 45b on the side opposite to the injection axis O _1, to form a curved portion 62 at the downstream end of the fuel injection direction in the first injection duct 45a Yes. Therefore, when the fuel in the sac portion 44 is injected into the combustion chamber 17 through the injection port 45, the cavitation bubbles generated on the first injection passage 45a side are not ruptured in the first injection passage 45a and in the vicinity of the curved surface portion 62. The fuel spray that has been ruptured and atomized is injected into the combustion chamber 17 while being guided by the curved surface portion 62, so that the fuel can be injected into the combustion chamber in the atomized state. Combustion stability can be improved by forming an air-fuel mixture.

  FIG. 8 is a longitudinal sectional view of a main part showing a fuel injection device according to Embodiment 4 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

In the fuel injection device according to the fourth embodiment, as shown in FIG. 8, the injection port 45 of the injector 27 is such that the injection axis O ₁ is inclined upward by a predetermined angle with respect to the central axis O _{2 of the} injector 27. α is set. In this injection port 45, the length La of the first injection passage 45a on the central axis O ₂ side of the injection port 45, that is, the upper surface side in FIG. 8, is opposite to the injection axis O ₁ , that is, the lower surface. The length is set shorter than the length Lb of the second injection passage 45b on the side. That is, the lower outer peripheral surface 43b on the side where the injection port 45 is formed is formed in a spherical shape with the center O of the sack portion 44 as a fulcrum at the tip end portion 43 of the housing 41, but the injection port 45 is not formed. The lower outer peripheral surface 43a on the side is formed into a spherical shape having a fulcrum (not shown) slightly above the center O of the sack portion 44, and a step is formed at the position of the injection port 45 on the lower outer peripheral surface of the tip portion 43. By adopting a simple shape, the length La of the first injection passage 45a and the length Lb of the second injection passage 45b are made different. In this case, the length La of the first injection passage 45a is preferably set to about ½ of the length Lb of the second injection passage 45b. A section Lc in which the first injection passage 45a does not exist with respect to the second injection passage 45b is set as a fuel spray run-up section. A curved surface portion 63 is formed at the injection port 45 between the upstream end portion of the second injection passage 45b in the fuel injection direction and the sac portion 44.

  Accordingly, when the needle valve 46 moves upward in the injector 27 to open the fuel passage 51, the fuel in the fuel passage 51 is supplied to the sac portion 44, and the combustion chamber 17 is supplied from the sack portion 44 through the injection port 45. Is injected into. At the time of fuel injection by the injector 27, in this embodiment, since the curved surface portion 63 is formed between the second injection passage 45b and the sac portion 44, the fluidity of the fuel flowing into the injection port 45 from the sac portion 44 is formed. And the generation of cavitation C in each of the injection passages 45a and 45b is promoted. Since the length La of the first injection passage 45a at the injection port 45 is set to be shorter than the length Lb of the second injection passage 45b, the generated cavitation bubbles are good without bursting in the first injection passage 45a. The pressure is released in the running section Lc from the injection port 45 to the combustion chamber 17, and the bubbles are injected while bursting. Therefore, the fuel spray is properly atomized by the burst of cavitation bubbles, and is injected into the combustion chamber 17 in the atomized state, and a high-quality air-fuel mixture is formed in the combustion chamber 17. Is done.

As described above, in the fuel injection device according to the fourth embodiment, the injection angle α is set by inclining the injection port 45 upward by a predetermined angle, and the curved surface portion 63 is provided between the second injection passage 45 b and the sac portion 44. And the length La of the first injection passage 45a on the central axis O ₂ side in the injection port 45 is set to be short. Accordingly, the fuel easily flows into the injection port 45 from the sac portion 44 and the generation of cavitation C is promoted, and the cavitation bubbles generated in the first injection passage 45a are not ruptured in the first injection passage 45a, and the combustion chamber 17 When the fuel is injected into the combustion chamber, the fuel can be injected into the combustion chamber in a state where the fuel is atomized by the rupture of the cavitation bubbles. By forming a high-quality air-fuel mixture in the combustion chamber, combustion stability is improved. Can be improved.

  In each of the above-described embodiments, the injection angle α and the spray angle β are set for the injection port 45 of the injector 27, but the spray angle β may be 0 degrees. In each embodiment, the fuel injection device of the present invention is applied to a direct injection internal combustion engine. However, the fuel injection device can also be applied to a port injection internal combustion engine that injects fuel into an intake port. be able to.

  As described above, the fuel injection device according to the present invention sets the length of the first injection passage on the injection valve axis side in the injection port to be shorter than the length of the second injection passage on the opposite side of the injection valve axis in the injection port. Thus, atomization by bursting of cavitation bubbles is possible, and it is suitable for use in any kind of internal combustion engine.

It is a principal part longitudinal cross-sectional view showing the fuel-injection apparatus which concerns on Example 1 of this invention. It is II-II sectional drawing of FIG. It is the schematic showing the cavitation generation | occurrence | production state in the injection opening of the fuel injection apparatus of Example 1. FIG. 2 is a graph showing the particle size of fuel spray with respect to the distance in the width direction of the injection port of the fuel injection device of Example 1; 1 is a schematic configuration diagram of an internal combustion engine to which a fuel injection device of Embodiment 1 is applied. It is a principal part longitudinal cross-sectional view showing the fuel-injection apparatus which concerns on Example 2 of this invention. It is a principal part longitudinal cross-sectional view showing the fuel-injection apparatus which concerns on Example 3 of this invention. It is a principal part longitudinal cross-sectional view showing the fuel-injection apparatus which concerns on Example 4 of this invention. It is a longitudinal cross-sectional view of the front-end | tip part of the conventional fuel injection apparatus. It is XX sectional drawing of FIG. It is the schematic showing the cavitation generation | occurrence | production state in the injection port of the conventional fuel injection apparatus.

Explanation of symbols

10 Engine 17 Combustion chamber 27 Injector (fuel injection valve)
28 Spark plug 35 Electronic control unit (ECU)
41 Housing 44 Suck Part 45 Injection Port 45a First Injection Passage 45b Second Injection Passage 46 Needle Valve (Injection Valve)
51 Fuel passage 54 Coil spring 55 Solenoid 62, 63 Curved surface E Separation C Cavitation

Claims (5)

  An injection port axis comprising: a housing having a fuel passage and a sac portion and an injection port communicating with the fuel passage at the tip; and an injection valve movably supported by the housing and capable of interrupting the fuel passage. In the fuel injection device formed by tilting at a predetermined angle with respect to the injection valve axis, the length of the first injection passage on the injection valve axis side at the injection port is opposite to the injection valve axis at the injection port A fuel injection device characterized in that it is set shorter than the length of the second injection passage.   2. The fuel injection device according to claim 1, wherein the injection port is formed in a left and right wide-angle fan shape and is inclined at a predetermined angle upward with respect to an axis of the injection valve. Fuel injection device.   2. The fuel injection device according to claim 1, wherein a length of the first injection passage is set to about ½ of a length of the second injection passage. 3.   2. The fuel injection device according to claim 1, wherein a curved surface portion is formed at a downstream end portion of the first injection passage in the fuel injection direction. 2. The fuel injection device according to claim 1, wherein a curved surface portion is formed between an upstream end portion of the second injection passage in a fuel injection direction and the sack portion.

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