JP2015055169A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve capable of improving atomization performance of fuel spray by increasing a pressing force of a fuel flow on fuel hole inner wall surface.SOLUTION: In a fuel injection valve including: a valve element 17 driven in a direction along a central axis 1a; a valve seat 15b separated/contacted by the valve element 17; a fuel chamber 53 arranged downward of the valve seat 15b for flowing fuel in a direction crossing the central axis 1a; and a plurality of injection holes 56 open to a bottom surface of the fuel chamber 53, a stepped surface 60 is formed on the bottom surface of the fuel chamber 53 such that a downstream side is higher than an upstream side and that inlet-side opening surfaces of the injection holes 56 are open to the stepped surface 60.

Description

  The present invention relates to a fuel injection valve that injects fuel.

  As a background art of this technical field, a fluid injection nozzle (fuel injection valve) described in Japanese Patent Application Laid-Open No. 2004-3519 (Patent Document 1) is known. In the fluid injection nozzle described in Patent Document 1, a recess is formed at the fuel injection side end of the valve body, and a parallel and flat disk-shaped fuel chamber is formed between the recess and the injection plate along the injection plate. Is formed. Four injection holes are formed on the same circumference in the injection plate, and the fuel chamber is formed to extend over a predetermined range around the injection holes immediately above the fuel upstream side of the injection holes. The nozzle holes are formed with the same diameter so as to be away from the central axis of the nozzle hole plate in the fuel injection direction. The fuel inlet of each nozzle hole is covered with the bottom surface of the recess, and opens to the outer fuel chamber formed by the nozzle plate and the bottom surface of the recess (see summary).

  In this fluid injection nozzle, the fuel flowing toward the nozzle hole plate along the valve seat surface collides with the nozzle hole plate, and then flows in the fuel chamber radially outward. This flow collides with the inner peripheral wall of the recess (fuel chamber) and changes the flow direction, creating a flow toward the center (radially inside) of the fuel chamber. Then, the flow toward the radially outer side and the flow toward the center of the fuel chamber by colliding with the inner peripheral wall of the recess collide evenly immediately above the fuel inlet of each nozzle hole and flow into each nozzle hole. The liquid column ejected from the turbulence is disturbed and atomization can be promoted (see paragraph 0024).

  In Patent Document 1, the fuel inlet (inlet side opening surface) of the nozzle hole is formed on a flat surface of the nozzle hole plate, and opens in parallel with the flow toward the radially outer side of the fuel chamber ( (See FIG. 1).

JP 2004-3519 A

  In Patent Document 1, a radially outward flow (outward lateral flow) and a radially inward flow (inward lateral flow) are caused to collide with each nozzle hole (injection hole) directly above the fuel inlet. To promote the atomization. For this reason, there is no consideration about increasing the pressing force for pressing the fuel flow against the inner wall surface of the injection hole. By causing the fuel flow caused by the lateral flow to flow into the injection hole so as to be pressed against the inner wall surface of the injection hole, the fuel flow is guided to the inner wall surface of the injection hole to generate a vortex. At this time, by increasing the pressing force on the inner wall surface of the injection hole in the fuel flow, the speed of the vortex is increased and the atomization performance of the fuel spray injected from the injection hole is improved.

  An object of the present invention is to provide a fuel injection valve that improves the atomization performance of fuel spray by increasing the pressing force on the inner wall surface of the injection hole in the fuel flow.

  In order to achieve the above object, a fuel injection valve according to the present invention includes a valve body that is driven in a direction along a central axis, a valve seat that contacts the valve body, and a central axis that is disposed on the downstream side of the valve seat. In the fuel injection valve comprising a fuel chamber for flowing fuel in a direction crossing the fuel chamber and a plurality of injection holes opened in the bottom surface of the fuel chamber, the downstream side of the bottom surface of the fuel chamber is higher than the upstream side of the fuel flow. A step surface is formed, and an inlet side opening surface of the injection hole is opened in the step surface.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel injection valve which improved the atomization performance of the fuel spray by enlarging the pressing force to the injection hole inner wall surface in a fuel flow can be provided.

1 is a cross-sectional view showing a cross section (longitudinal cross section) along a valve axis (center axis) 1a of a fuel injection valve 1; It is sectional drawing which expands and shows the valve part 7 and the injection part 21. FIG. It is the external view (plan view) which looked at the injection part 21 shown to FIG. 2A from the arrow IIB direction. It is a top view (III-III arrow line view of FIG. 2A) which shows the base end side end surface (upper surface) of the injection hole plate 21b, and has shown the back surface side of the surface shown to FIG. 2B. 4 is an enlarged cross-sectional view showing the vicinity of one injection hole 56. FIG. It is sectional drawing of the injection hole plate 21b which shows the modification of a level | step difference surface. It is sectional drawing which expanded and showed the part of the injection hole 56-5 in FIG. 2A. It is a schematic diagram which shows the fuel flow in the AA arrow surface of FIG. It is a schematic diagram which shows the fuel flow in the BB arrow cross section of FIG. It is a schematic diagram which shows the fuel flow in the CC arrow cross section of FIG. It is a schematic diagram which shows the fuel flow in the DD arrow plane of FIG. It is the figure which looked at the injection part 21 from the front end side, and is a top view drawn with the fuel spray injected from each injection hole 56. FIG. 1 is a cross-sectional view of an internal combustion engine in which a fuel injection valve 1 is mounted.

  An embodiment of the present invention will be described with reference to FIGS.

  With reference to FIG. 1, the whole structure of the fuel injection valve 1 is demonstrated. FIG. 1 is a cross-sectional view showing a cross section (longitudinal cross section) along a valve axis (center axis) 1a of the fuel injection valve 1. As shown in FIG. The central axis 1a coincides with the axis of a mover 27 provided integrally with a valve body 17 described later, and coincides with the central axis of a cylindrical body 5 described later.

  The fuel injection valve 1 is constituted by a cylindrical body 5 made of a metal material so that the fuel flow path 3 is substantially along the central axis 1a. The cylindrical body 5 is formed in a stepped shape in the direction along the central axis 1a by press working such as deep drawing using a metal material such as magnetic stainless steel. Thereby, as for the cylindrical body 5, the diameter of the one end side 5a is large with respect to the diameter of the other end side 5b. In FIG. 1, the large diameter portion 5 a formed on one end side is drawn to be above the small diameter portion 5 b formed on the other end side.

  In FIG. 1, the upper end portion (upper end side) is referred to as a base end portion (base end side), and the lower end portion (lower end side) is referred to as a distal end portion (front end side). Alternatively, it may be referred to as an upper end (upper end) or a lower end (lower end), but this is based on FIG. 1 and is related to the vertical direction when the fuel injection valve 1 is mounted on an internal combustion engine. There is no.

  A fuel supply port 2 is provided at the proximal end of the cylindrical body 5, and a fuel filter 13 for removing foreign matters mixed in the fuel is attached to the fuel supply port 2. The fuel filter 13 includes a cylindrical metal core 13a, a resin material frame 13b, and a mesh-shaped filter body 13c. The resin material of the frame 13b is, for example, nylon, fluororesin or the like, and is molded integrally with the core metal 13a. The filter main body 13c is attached to the frame 13b, and is fixed to the base end portion of the cylindrical body 5 by press-fitting the cored bar 13a inside the large diameter portion 5a of the cylindrical body 5.

  The base end portion of the cylindrical body 5 is formed with a bent portion (expanded portion) 5d that is bent so as to expand toward the radially outer side, and the bent portion 5d and the base end side end portion 47a of the cover 47 are formed. An O-ring 11 is disposed in the formed annular recess (annular groove) 4.

  A valve portion 7 including a valve body 17 and a valve seat member 15 is configured at the distal end portion of the cylindrical body 5. The valve seat member 15 has a stepped valve body housing hole 15a for housing the valve body 17, and a valve seat 15b is formed on a conical surface formed in the middle of the valve body housing hole 15a. A guide surface 15c for guiding the valve body 17 in the direction along the central axis 1a is formed on the upstream side (base end side). A diameter-enlarged portion 15d that increases in diameter toward the upstream side is formed on the upstream side of the guide surface 15c. The enlarged diameter portion 15d facilitates the assembly of the valve body 17 and serves to enlarge the fuel passage cross section.

  The valve seat member 15 is inserted inside the front end side of the cylindrical body 5 and is fixed to the cylindrical body 5 by laser welding. The laser welding 19 is performed from the outer peripheral side of the cylindrical body 5 over the entire periphery. The valve body accommodating hole 15a penetrates the valve seat member 15 in the direction along the central axis 1a, and an injection formed by laminating an intermediate plate 21a (see FIG. 2A) and an injection hole plate 21b (see FIG. 2A). The part 21 is attached to the distal end side end surface of the valve seat member 15 so as to close the opening on the distal end side by the valve body accommodation hole 15a. The injection unit 21 is fixed by laser welding to the valve seat member 15 in a state where the intermediate plate 21a and the injection hole plate 21b are stacked. The laser welding portion 23 makes a round around the injection hole forming region so as to surround the injection hole forming region where the injection hole 22 is formed. The valve seat member 15 may be fixed to the tubular body 5 by laser welding after being press-fitted inside the distal end side of the tubular body 5.

  In the present embodiment, the valve body 17 uses a ball valve having a spherical shape. For this reason, a plurality of notch surfaces 17a are provided at intervals in the circumferential direction at a portion of the valve body 17 that contacts the guide surface 15c, and a fuel flow path is configured by the notch surfaces 17a. It is also possible to constitute the valve body 17 other than the ball valve. For example, you may use the nozzle needle as described in patent document 1 in which the fuel-injection side end surface was formed in planar shape.

  A drive unit 9 for driving the valve body 17 is disposed in the middle part of the cylindrical body 5. The drive unit 9 is composed of an electromagnetic actuator. Specifically, the drive unit 9 is disposed on the front end side with respect to the fixed iron core 25 inside the cylindrical body 5 and the fixed iron core 25 fixed inside (inner peripheral side) of the cylindrical body 5. An electromagnetic wave extrapolated to the outer peripheral side of the cylindrical body 5 at a position where the movable element (movable member) 27 movable in the direction along the axis 1a, the fixed iron core 25 and the movable iron core 27 face each other with a minute gap δ. The coil 29 and the yoke 33 that covers the electromagnetic coil 29 on the outer peripheral side of the electromagnetic coil 29 are configured. The movable iron core 27 a, the fixed iron core 25, and the yoke 33 formed in the mover 27 constitute a closed magnetic path through which a magnetic flux generated by energizing the electromagnetic coil 29 flows. Although the magnetic flux passes through the minute gap δ, a magnetic aperture 5c is provided at a position corresponding to the minute gap δ of the cylindrical body 5 in order to reduce the leakage magnetic flux flowing through the cylindrical body 5 at the portion of the minute gap δ. Yes. This magnetic diaphragm can be constituted by a demagnetization process on the cylindrical body 5 or an annular recess formed on the outer peripheral surface of the cylindrical body 5.

  The electromagnetic coil 29 is wound around a bobbin 31 formed in a cylindrical shape with a resin material, and is extrapolated to the outer peripheral side of the cylindrical body 5. The electromagnetic coil 29 is electrically connected to a connector pin 43 provided on the connector 41 via a wiring member 45. A drive circuit (not shown) is connected to the connector 41, and a drive current is passed through the electromagnetic coil 29 via the connector pin 43 and the wiring member 45.

  The fixed iron core 25 is made of a magnetic metal material. The fixed iron core 25 is formed in a cylindrical shape, and has a through hole 25a that penetrates the central portion in a direction along the central axis 1a. The fixed iron core 25 is press-fitted and fixed to the proximal end side of the small-diameter portion 5 b of the cylindrical body 5, and is positioned at the intermediate portion of the cylindrical body 5. Since the large diameter portion 5a is provided on the base end side of the small diameter portion 5b, the fixed iron core 25 can be easily assembled. The fixed iron core 25 may be fixed to the cylindrical body 5 by welding, or may be fixed to the cylindrical body 5 by using welding and press fitting together.

  The movable element 27 has a large-diameter portion 27 a formed on the base end side, and the large-diameter portion 27 a constitutes a movable iron core 27 a that faces the fixed iron core 25. A small diameter portion 27b is formed on the distal end side of the movable iron core 27a, and the valve body 17 is fixed to the distal end of the small diameter portion 27b by welding. The small diameter portion 27b constitutes a connection portion 27b that connects the movable iron core 27a and the valve body 17. In this embodiment, the movable iron core 27a and the connecting portion 27b are integrally formed (one member made of the same material), but two members may be joined. In this embodiment, the valve element 17 is a separate component from the movable element 27, but the valve element 17 may be included in a part of the movable element 27. Moreover, when the outer peripheral surface of the movable iron core 27a contacts the inner peripheral surface of the cylindrical body 5, the mover 27 is guided to move in the direction along the central axis 1a (the on-off valve direction). An annular protrusion is formed along the circumferential direction at the position indicated by reference numeral 27g (the outer peripheral surface of the movable core 27a) so as to reduce the sliding resistance between the outer peripheral surface of the movable core 27a and the inner peripheral surface of the cylindrical body 5. May be.

  The movable iron core 27a is formed with a recess 27c that opens to an end surface facing the fixed iron core 25. An annular surface 27e serving as a spring seat of a spring (coil spring) 39 is formed on the bottom surface of the recess 27c. A through hole 27f is formed on the inner peripheral side of the annular surface 27e so as to penetrate the distal end side end of the small diameter portion (connecting portion) 27b along the central axis 1a. The small diameter portion 27b has an opening 27d on the side surface. A back pressure chamber 37 is formed between the outer peripheral surface of the small diameter portion 27 b and the inner peripheral surface of the cylindrical body 5. The through hole 27f opens at the bottom surface of the recess 27c, and the opening 27d opens at the outer peripheral surface of the small diameter portion 27b, so that the base end side of the mover 27 and the side surface portion of the mover 27 are formed inside the mover 27. The fuel flow path 3 is formed to communicate with the back pressure chamber 37 formed in the above.

  A coil spring 39 is disposed in a compressed state across the through hole 25a of the fixed iron core 25 and the recess 27c of the movable iron core 27a. The coil spring 39 functions as a biasing member that biases the movable element 27 in a direction (valve closing direction) in which the valve element 17 contacts the valve seat 15b. An adjuster 35 is disposed inside the through hole 25 a of the fixed iron core 25, and a proximal end side end portion of the coil spring 39 is in contact with a distal end side end surface of the adjuster 35. By adjusting the position of the adjuster 35 in the through hole 25a in the direction along the central axis 1a, the urging force of the movable element 27 (that is, the valve body 17) by the coil spring 39 is adjusted.

  The adjuster 35 has a fuel flow path 3 that penetrates the central portion in a direction along the central axis 1a. After flowing through the fuel flow path 3 of the adjuster 35, the fuel flows into the fuel flow path 3 at the tip side portion of the through hole 25 a of the fixed iron core 25, and then flows into the fuel flow path 3 configured in the mover 27.

  The yoke 33 is made of a metallic material having magnetism, and also serves as a housing for the fuel injection valve 1. The yoke 33 is formed in a stepped cylindrical shape having a large diameter portion 33a and a small diameter portion 33b. The large diameter portion 33a has a cylindrical shape covering the outer periphery of the electromagnetic coil 29, and a small diameter portion 33b having a smaller diameter than the large diameter portion 33a is formed on the distal end side of the large diameter portion 33a. The small diameter portion 33 b is press-fitted into the outer periphery of the small diameter portion 5 b of the cylindrical body 5. Thereby, the inner peripheral surface of the small-diameter portion 33 b is in contact with the outer peripheral surface of the cylindrical body 5. At this time, at least a part of the inner peripheral surface of the small-diameter portion 33b is opposed to the outer peripheral surface of the movable iron core 27a via the cylindrical body 5, and the magnetic resistance of the closed magnetic path at this facing portion is reduced.

  An annular recess 33c is formed along the circumferential direction on the outer peripheral surface of the end portion on the front end side of the yoke 33. In the thin part formed in the bottom face of the annular recess 33 c, the yoke 33 and the cylindrical body 5 are joined over the entire circumference by laser welding 24. The yoke 33 has a distal end side end located on the distal end side with respect to the proximal end side end of the valve seat member 15. For this reason, the yoke 33 and the valve seat member 15 are provided in an overlapping range in the direction along the central axis 1a, and the tip of the cylindrical portion 5 is reinforced. Note that the laser welding portion 19 of the valve seat member 15 is located further to the front end side than the end portion on the front end side of the yoke 33 so that the assembly order of the valve seat member 15 and the yoke 33 is not restricted. .

  A cylindrical protector 49 having a flange portion 49 a is extrapolated to the distal end portion of the tubular body 5, and the distal end portion of the tubular body 5 is protected by the protector 49. The protector 49 covers the top of the laser welding portion 24 of the yoke 33.

  An annular groove 34 is formed by the flange portion 49a of the protector 49, the small diameter portion 33b of the yoke 33, and the step surface of the large diameter portion 33a and the small diameter portion 33b of the yoke 33, and an O-ring 46 is extrapolated to the annular groove 34. Has been. The O-ring 46 is located between the inner peripheral surface of the insertion port 105a (see FIG. 7) formed on the internal combustion engine side and the outer peripheral surface of the small diameter portion 33b in the yoke 33 when the fuel injection valve 1 is attached to the internal combustion engine. It functions as a seal that ensures liquid tightness and air tightness.

  A resin cover 47 is molded and covered from the middle portion of the fuel injection valve 1 to the vicinity of the proximal end portion. The end portion on the front end side of the resin cover 47 covers a part of the base end side of the large diameter portion 33 a of the yoke 33. The resin cover 47 covers the wiring member 45, and the connector 41 is integrally formed by the resin cover 47.

  Next, the operation of the fuel injection valve 1 will be described.

  When the electromagnetic coil 29 is not energized (that is, when no drive current flows), the mover 27 is urged in the valve closing direction by the coil spring 39, and the valve element 17 is in contact (seat) with the valve seat 15b. It is in. In this case, a gap δ exists between the distal end side end surface of the fixed iron core 25 and the proximal end side end surface of the movable iron core 27a. In this embodiment, the gap δ is equal to the stroke of the mover 27 (that is, the valve body 17).

  When the electromagnetic coil 29 is energized and a drive current flows, a magnetic flux is generated in a closed magnetic path constituted by the movable iron core 27a, the fixed iron core 25, and the yoke 33. Due to this magnetic flux, a magnetic attractive force is generated between the fixed iron core 25 and the movable iron core 27a facing each other across the gap δ. When this magnetic attraction force overcomes the urging force of the coil spring 39 or the resultant force such as the fuel pressure acting on the mover 27 in the valve closing direction, the mover starts moving in the valve opening direction. When the valve body 17 is separated from the valve seat 15b, a gap (fuel flow path) is formed between the valve body 17 and the valve seat 15b, and fuel injection starts. In this embodiment, when the movable element 27 moves in the valve opening direction by a distance δ equal to the gap δ and the movable iron core 27a contacts the fixed iron core 25, the movable iron core 27a is stopped from moving in the valve opening direction, The valve opens and reaches a stationary state.

  When the energization of the electromagnetic coil 29 is cut off, the magnetic attractive force decreases and eventually disappears. At this stage, when the magnetic attractive force becomes smaller than the biasing force of the coil spring 39, the mover 27 starts to move in the valve closing direction. When the valve element 17 comes into contact with the valve seat 15b, the valve element 17 closes the valve portion 7 and comes to a stationary state.

  In order to reduce the squeeze force acting between the movable iron core 27a and the fixed iron core 25, a protrusion may be provided on the end surface of the movable iron core 27a facing the fixed iron core 25. In such a case, the moving distance (stroke) of the valve body 17 is a size obtained by subtracting the protrusion height from the gap δ. Moreover, before the movable iron core 27a and the fixed iron core 25 contact, the stopper which restrict | limits the movement to the valve opening direction of the needle | mover 27 may be provided.

  Next, the structures of the valve unit 7 and the injection unit 21 will be described in detail with reference to FIGS. 2A, 2B, and 3 to 5. FIG. 2A is an enlarged cross-sectional view showing the valve unit 7 and the injection unit 21. 2B is an external view (plan view) of the injection unit 21 shown in FIG. 2A viewed from the direction of the arrow IIB. FIG. 3 is a plan view (III-III arrow view of FIG. 2A) showing the base end side end surface (upper surface) of the injection hole plate 21b, and shows the back surface side of the surface shown in FIG. 2B. FIG. 4 is an enlarged cross-sectional view showing the vicinity of one injection hole 56. FIG. 5 is a cross-sectional view of the injection hole plate 21b showing a modification of the step surface.

  The injection unit 21 has a double plate structure in which an intermediate plate 21a and an injection hole plate 21b are stacked in the direction of the central axis 1a. The injection hole plate 21b is disposed on the tip side with respect to the intermediate plate 21a. The intermediate plate 21a and the injection hole plate 21b are formed of a metal plate such as stainless steel. Further, the intermediate plate 21a and the injection hole plate 21b have a circular shape having substantially the same radius, and the outer periphery of each of the intermediate plate 21a and the injection hole plate 21b is in contact with the inner peripheral surface of the cylindrical body 5, and A gap is not formed between the inner peripheral surface of the cylindrical body 5.

  A radius Ra with a central axis 1a as a central axis is provided at a downstream end portion (tip end portion) of a conical surface on which a valve seat 15b is formed on a distal end surface of the valve seat member 15 constituting the valve portion 7. A through-hole formed by a cylindrical surface (inner peripheral surface) 15e is connected. The cylindrical surface 15e forms an opening surface 15f at the end surface on the distal end side of the valve seat member 15. The cylindrical surface 15e forms a fuel chamber 51 on the upstream side of the intermediate plate 21a.

  A bulging portion 52 is formed in the center of the injection hole plate 21b within a radius Rc centered on the central axis 1a. The bulging portion 52 forms a fuel chamber 53 between the lower surface (end surface located on the distal end side) of the intermediate plate 21a and the upper surface (end surface located on the proximal end side) of the injection hole plate 21b. As shown in FIG. 2A, the bulging portion 52 is formed as a spherical surface protruding to the opposite side of the intermediate plate 21a. The radius Rc in the range where the bulging portion 52 is formed is equal to or larger than the radius Rd of the cylindrical surface 15e.

  The injection hole plate 21b has a flat portion (planar portion) 52a formed on the outer peripheral side of the bulging portion 52 in contact with the intermediate plate 21a. The flat portion 52a is welded to the valve seat member 15 together with the intermediate plate 21a. ing. That is, the intermediate plate 21a and the injection hole plate 21b are laminated so that the intermediate plate 21a is positioned on the valve seat member 15 side with respect to the injection hole plate 21b, and is joined to the front end side end surface of the valve seat member 15. Yes.

  A communication hole 54 is formed in the central portion of the intermediate plate 21a to connect the upstream fuel chamber 51 and the downstream fuel chamber 53 to the intermediate plate 21a. The communication hole 54 constitutes a fuel supply port (fuel introduction port) 54 for supplying fuel from the fuel chamber 51 to the fuel chamber 53. The fuel supply port 54 is formed in a circular shape having a radius Ra and a diameter φ on the central axis 1a. As shown in FIG. 2A, the radius Ra of the fuel supply port 54 is smaller than the radius Rc of the bulging portion 52. The radial position Ro of the inlet side opening surface of the plurality of injection holes 56 is smaller than the radii Rd and Rc and larger than the radius Ra. The lower surface of the intermediate plate 21a (the end surface located on the front end side) covers the entire inlet side opening surface above the inlet side opening surfaces of the plurality of injection holes 56. Further, the radius Rd of the cylindrical surface 15e is larger than the radius Ra of the fuel supply port 54.

  The fuel flow path downstream from the opening edge of the fuel supply port 54 is formed so that the cross-sectional area gradually decreases. That is, the cross-sectional area along the circumferential direction of the fuel chamber 53 gradually decreases toward the radially outer side.

  The inlet-side opening surfaces of the plurality of injection holes 56 open to the bottom surface of the fuel chamber 53. The bottom surface of the fuel chamber 53 is constituted by the end face of the injection hole plate 21 b and is constituted by the inner wall surface of the bulging portion 52. The bottom surface (inner wall surface of the bulging portion 52) on which the inlet-side opening surface of the injection hole 56 is formed is a curved surface that is curved in the radial direction. This curved surface may be a spherical surface, for example. This spherical surface forms an inner wall surface that is recessed in a bowl shape (concave shape).

  As shown in FIG. 2B, six outlet side opening surfaces 56-1b to 56-6b of the injection holes 56-1 to 56-6 are provided on the front end surface of the injection unit 21 (the front end side end surface of the injection hole plate 21b). Is formed. In FIG. 2B, the inlet side opening surfaces of the fuel supply port 54 and the injection holes 56-1 to 56-6 are indicated by broken lines. A center Oa shown in FIG. 2B is an intersection where the central axis 1a intersects the injection hole plate 21b, and represents the center of the tip surface of the injection unit 21.

  As shown in FIG. 3, the inlet side opening surfaces 56-1a to 56-6a of the injection holes 56-1 to 56-6 are arranged on the circumference of the radius Ro having the center Ob on the central axis 1a. In FIG. 3, the outlet side opening surfaces 56-1b to 56-6b of the injection holes 56-1 to 56-6 are indicated by broken lines.

  The circumference indicated by reference numerals 60 a and 60 b in FIG. 3 represents the step surface 60. The step surface 60 is formed in an annular shape having a center on the central axis 1a. Reference numeral 60 a is an outer peripheral edge of the step surface 60, and reference numeral 60 b is an inner peripheral edge of the step surface 60. As shown in FIG. 4, a portion 21bo on the outer peripheral side from the circumference 60a and a portion 21bi on the inner peripheral side from the circumference 60b are an extension line extending from the outer peripheral portion 21bo to the inner peripheral side and the inner peripheral side. The portion 21bi is connected via a step surface 60 that forms a step height ha so that it does not overlap with an extension line extending to the outer peripheral side. A fixed portion (joining portion) 21bf having a flat surface is formed on the outer peripheral portion 21bo of the injection hole plate 21b. The step surface 60 is provided between the fixed portion 21bf of the injection hole plate 21b and the inner peripheral portion 21bi.

  The inner wall surface (upper surface) of the bulging portion 52 in which the inlet-side opening surface of the injection hole 56 is formed is a curved surface that is curved in the radial direction. The fuel flow indicated by Ff in FIG. 3 is not guided by the bowl-shaped inner wall surface on the inlet opening surface of the injection hole 56. For this reason, it collides with the semicircle part (range shown by RA of FIG. 7A) located in the outer peripheral side among the internal peripheral surfaces (inner wall surface) of the injection hole 56, and the inflow to the injection hole 56 is promoted. Further, since the step surface 60 rises so that the inlet side opening surface of the injection hole 56 rises toward the fuel flow, the fuel flow further promotes the inflow into the injection hole 56 as shown by an arrow Ffa in FIG. It is. In the present embodiment, the fuel that has flowed into the fuel chamber 53 flows in the radial direction toward the outer peripheral side. For this reason, as shown in FIGS. 2A and 4, the peripheral edge of the inlet side opening surface of the injection hole 56 is higher at the outer peripheral side than at the inner peripheral side (positioned on the intermediate plate 21 a side). Step surface 60 is formed.

  In the injection hole plate 21 b, an extension line extending virtually from the inner peripheral side portion 21 bi to the outer peripheral side along the inner peripheral side portion 21 bi intersects the inner wall surface of the injection hole 56 with respect to the step surface 60. Configured as follows.

  In the present embodiment, the inner peripheral portion 21bi is formed of a spherical surface. However, since the step surface 60 is provided, the inner peripheral portion 21bi may be formed of a plane orthogonal to the central axis 1a. The inflow of the fuel flow into the injection hole 56 can be promoted, and the pressing force on the inner wall surface of the injection hole in the fuel flow can be increased. Moreover, you may comprise the part 21bo of the outer peripheral side of the injection hole plate 21b not by a spherical surface but by the inclined surface (conical surface).

  In the present embodiment, the entire inlet side opening surface of the injection hole 56 is formed inside the step surface 60. In order to increase the pressing force on the inner wall surface of the injection hole in the fuel flow, the peripheral edge of the inlet side opening surface of the injection hole 56 should be higher at the outer peripheral side than at the inner peripheral side. What is necessary is just to be located in the intermediate | middle plate 21a side. Therefore, the step surface 60 does not need to be formed on the entire entrance-side opening surface. For example, as shown in FIG. 5, the step surface 60 may be formed on a part of the entrance-side opening surface.

  In FIG. 5, the step surface 60 is provided so as to cross the center of the inlet side opening surface of the injection hole 56 having the radius Rh. Therefore, the distance between the portion located on the outermost peripheral side of the injection hole 56 and the step surface 60 is Rh, and the distance between the portion located on the innermost peripheral side of the injection hole 56 and the step surface 60 is Rh. And both are equal. The step surface 60 does not need to be provided so as to cross the center of the inlet side opening surface of the injection hole 56. Further, the step surface 60 may be inclined with respect to the central axis 1a. However, when the step surface 60 is largely shifted to the left or right side in FIG. 5, the circumferential range of the inner wall surface of the injection hole to which the fuel flow is pressed against the fuel flow is narrowed. In order for the fuel flow to generate the vortex described in FIGS. 6 and 7A to 7D, a step surface 60 is provided so as to cross the vicinity of the center of the inlet side opening surface of the injection hole 56 as shown in FIG. It is preferable to secure a wide range in the circumferential direction of the inner wall surface of the injection hole 56 against which is pressed.

  In addition, the step surface 60 that forms the entire inlet-side opening surface of the injection hole 56 and the inner peripheral side portion 21bi of the injection hole plate 21b are both formed as spherical surfaces, and the curvatures of both spherical surfaces may be changed. Good. In this case, by making the curvature of the step surface 60 larger than the curvature of the inner peripheral portion 21bi, the inlet side opening surface of the injection hole 56 can be made to face the fuel flow.

  In any case described above, it is necessary to press the fuel flow against the inner wall surface of the injection hole 56. If the opening surface on the inlet side of the injection hole 56 rises too much so as to stand up toward the fuel flow, the fuel flow flows toward the outlet side opening surface of the injection hole 56 without being pressed against the inner wall surface of the injection hole 56. End up. Therefore, it is necessary to make the inner wall surface of the injection hole 56 visible when viewed from the flow direction of the fuel flowing through the portion 21bi on the inner peripheral side of the injection hole plate 21b. It is desirable to raise the inlet side opening surface of the injection hole 56 so as to stand up toward the fuel flow.

  In the present embodiment, the injection holes 56-1 to 56-3 inject fuel toward the left side in FIG. The injection holes 56-4 to 56-6 inject fuel to the right side in FIG. The number of the injection holes 56 need not be limited to the number (6) of the present embodiment, and may be 4, 8, 12, or other numbers, for example.

  In the present embodiment, the injection holes 56-2 and 56-5 inject fuel in a direction perpendicular to the center line CLa (a direction parallel to the center line CLa) (see FIG. 2B). The outlet side opening surfaces 56-2b and 56-5b are arranged at positions shifted radially outward (radially outer peripheral side) with respect to the opening surfaces 56-2a and 56-5a. The injection holes 56-1 and 56-4 are formed in the inlet-side opening surfaces 56-1a and 56-4a so as to inject fuel in a direction inclined toward the center line CLb with respect to the center line CLc (see FIG. 2B). On the other hand, the outlet side opening surfaces 56-1b and 56-4b are disposed at positions shifted radially outward (radially outer peripheral side) and shifted away from the center line CLa. The injection holes 56-3 and 56-6 are formed in the inlet-side opening surfaces 56-1a and 56-4a so as to inject fuel in a direction inclined toward the center line CLb with respect to the center line CLd (see FIG. 2B). On the other hand, the outlet side opening surfaces 56-1b and 56-4b are disposed at positions shifted radially outward (radially outer peripheral side) and shifted away from the center line CLa.

  Thereby, the center axis line of the injection holes 56-2 and 56-5 overlaps with the center line CLb. Further, the central axes CL56-1, CL56-3, CL56-4, and CL56-6 of the injection holes 56-1, 56-3, 56-4, and 56-6 have inclinations as shown in FIG. The injection holes 56-1, 56-3, 56-4, 56-6 are inclined so that the central axes CL56-1, CL56-3, CL56-4, CL56-6 are parallel to the central line CLb. May be.

  The injection directions Ds1 to Ds3 of the fuel sprays injected from the injection holes 56-1 to 56-3 arranged on the left side of the center line CLa are projected on a plane (for example, on FIG. 2B) orthogonal to the center axis 1a. In each case, each is generally directed to the left. On the other hand, the injection directions Ds4 to Ds6 of each fuel spray injected from the injection holes 56-4 to 56-6 disposed on the right side of the center line CLa are on a plane (for example, on the upper side of FIG. 2B) orthogonal to the center axis 1a. When projected, each is generally directed to the right. Each fuel spray injected from the injection holes 56-1 to 56-3 and each fuel spray injected from the injection holes 56-4 to 56-6 are injected in opposite directions with the center line CLa as a boundary. The fuel sprays injected from the injection holes 56-1 to 56-3 are combined to form a fuel spray injected in one direction, and the fuel sprays injected from the injection holes 56-4 to 56-6 are combined. A fuel spray injected in the other direction is formed, and a fuel spray injected in the two directions (two-way spray) is formed.

  In FIG. 3, center lines CLa, CLb, CLc and CLd pass through the center Ob. At this time, the angles θo formed between the center lines CLb, CLc, and CLd are provided uniformly (45 °), but the angles between the center lines may be different. It can be appropriately changed according to the internal combustion engine to be mounted.

  2B and 3, the configuration in the case of forming the fuel spray injected in two directions has been described. However, in the case of forming the fuel spray injected in one direction, the injection holes 56-1, 56-3, 56-4 and 56-6 may be formed as follows. The injection holes 56-1 and 56-4 are formed so that the central axes CL56-1 and CL56-4 are parallel to the central line CLc. The injection holes 56-3 and 56-6 are formed such that their central axes CL56-3 and CL56-6 are parallel to the center line CLd. Thereby, the injection direction of the fuel injected from the injection holes 56-1, 56-3, 56-4, and 56-6 is drawn radially from the center Oa (FIG. 2A).

  In the present embodiment, the injection unit 21 includes the intermediate plate 21a and the injection hole plate 21b. However, the valve seat member 15 can also function as the intermediate plate 21a.

  With reference to FIG. 6, FIG. 7A-FIG. 7D, and FIG. 8, the behavior of the fuel flow in the injection hole 56 is demonstrated. FIG. 6 is an enlarged cross-sectional view showing a portion of the injection hole 56-5 in FIG. 2A. FIG. 7A is a schematic diagram showing the fuel flow in the AA arrow plane of FIG. FIG. 7B is a schematic diagram showing a fuel flow in a cross section taken along the line B-B in FIG. 6. FIG. 7C is a schematic diagram illustrating a fuel flow in a cross section taken along the line CC in FIG. 6. FIG. 7D is a schematic diagram illustrating a fuel flow in a DD arrow plane in FIG. 6. FIG. 8 is a view of the injection unit 21 as viewed from the tip side, and is a plan view drawn together with the fuel spray injected from each injection hole 56.

  In FIG. 7A, the fuel flow Ffa flowing from the center side of the fuel chamber 53 to the radially outer side (outer peripheral direction) flows into the injection hole 56. Of the fuel flow Ffa flowing from the center side of the fuel chamber 53 toward the radially outer side, the flow that has not flowed into the injection hole 56 collides with the radial end of the fuel chamber 53 and flows radially inward. Change the direction. The fuel flow whose direction is changed inward in the radial direction reaches the inlet opening surface of the injection hole 56 and flows into the injection hole 56 from the range indicated by RA.

  As described above, the flow that collides with the semicircular portion (range indicated by RA) located on the outer peripheral side of the inner peripheral surface (inner wall surface) of the injection hole 56 is urged to flow into the injection hole 56. The flow flowing into the injection hole 56 is strongly pressed against the inner wall surface of the injection hole 56. At this time, as indicated by an arrow Ff1, the fuel flow swirls along the inner peripheral surface of the injection hole 56 from both ends in the direction orthogonal to the streamline direction of the fuel flow Ffa, and reaches the most from the inflow side of the fuel flow Ffa. It flows so as to concentrate at a distant inner peripheral surface position 56C.

  As shown in FIG. 7B, the fuel flow concentrated at the inner peripheral surface position 56 </ b> C becomes a fuel flow Ff <b> 2 from the inner wall surface of the injection hole 56 toward the center as it flows in the axial direction of the injection hole 56.

  In FIG. 7C, as indicated by an arrow Ff3, the gas flows through the central portion of the injection hole 56 so as to cross the injection hole 56 in the radial direction.

  As shown in FIGS. 7B and 7C, the fuel flow that traverses the injection hole 56 in the radial direction is the vertical direction as shown in FIG. 6 (the axial direction of the injection hole 56 as the fuel flows in the axial direction of the injection hole 56. ) Produces a swirling flow.

  As a result, as shown in FIG. 7D, the fuel spray SP has a flat cross section (cross section). As the flow velocity of the lateral flow in the fuel chamber 53 is increased, the flow is more strongly pressed against the inner wall surface of the injection hole 56, and the behavior shown in FIGS. 7A to 7D becomes remarkable. Further, as described above, the flow line of the lateral flow collides with the inner peripheral surface of the injection hole 56 (the range indicated by RA in FIG. 7A), thereby promoting the inflow of the fuel flow into the injection hole 56, The flow is strongly pressed against the inner wall surface of the injection hole 56, and the behavior shown in FIGS. 7A to 7D becomes remarkable. The major axis direction AXa and the minor axis direction AXb of the flat fuel spray SP are considered to be affected not only by the flow direction of the fuel flow Ffa but also by the inclination direction of the injection hole 56.

  Since each fuel spray injected from the injection holes 56-1, 56-2, 56-3, 56-4, 56-5, 56-6 has a flat cross-sectional shape, as shown in FIG. Interference between the fuel sprays SP-1, SP-2, SP-3 injected from the injection holes 56-1, 56-2, 56-3 hardly occurs and the injection holes 56-4, 56-5, 56. Interference between fuel sprays SP-4, SP-5, and SP-6 injected from −6 hardly occurs. For this reason, it can prevent that a particle size expands by spraying interfering. Thereby, the atomized fuel spray can be formed.

  With reference to FIG. 9, an internal combustion engine equipped with a fuel injection valve according to the present invention will be described. FIG. 9 is a cross-sectional view of the internal combustion engine on which the fuel injection valve 1 is mounted.

  A cylinder 102 is formed in the engine block 101 of the internal combustion engine 100, and an intake port 103 and an exhaust port 104 are provided at the top of the cylinder 102. The intake port 103 is provided with an intake valve 105 that opens and closes the intake port 103, and the exhaust port 104 is provided with an exhaust valve 106 that opens and closes the exhaust port 104. An intake pipe 108 is connected to an inlet side end 107 a of an intake passage 107 formed in the engine block 101 and communicating with the intake port 103.

  A fuel pipe 110 is connected to the fuel supply port 2 of the fuel injection valve 1.

  An attachment portion 109 for the fuel injection valve 1 is formed in the intake pipe 108, and an insertion port 109 a for inserting the fuel injection valve 1 is formed in the attachment portion 109. The insertion port 109a penetrates to the inner wall surface (intake flow path) of the intake pipe 108, and the fuel injected from the fuel injection valve 1 inserted into the insertion port 109a and attached to the intake pipe 108 enters the intake flow path. Be injected. In the case of the two-way spray described above, each fuel spray is injected toward each intake port 103 (intake valve 105) for an internal combustion engine in which two intake ports 103 are provided in the engine block 101. .

  Further, the arrangement, number and angle of the injection holes 56 and the injection direction and number of the fuel spray are not limited to the above-described form, and can be appropriately changed according to the form of the internal combustion engine.

  DESCRIPTION OF SYMBOLS 1a ... Center axis, 5 ... Cylindrical body, 7 ... Valve part, 15 ... Valve seat member, 15a ... Valve body accommodation hole, 15b ... Valve seat, 15c ... Guide surface, 15d ... Expanded diameter part, 15e ... Cylindrical surface ( (Inner peripheral surface), 15f ... opening surface, 21 ... injection part, 21a ... intermediate plate, 21b ... injection hole plate, 51 ... fuel chamber, 52 ... bulge part, 53 ... fuel chamber, 54 ... fuel supply port (fuel introduction port) Mouth), 56 (56-1 to 56-6) ... injection hole, 57 ... reverse protrusion, 60 ... step surface.

Claims (4)

A valve body driven in a direction along the central axis, a valve seat to which the valve body is separated, a fuel chamber disposed downstream of the valve seat and for flowing fuel in a direction crossing the central axis, and a bottom surface of the fuel chamber In a fuel injection valve comprising a plurality of injection holes that open to
A fuel injection valve characterized in that a step surface is formed on the bottom surface of the fuel chamber so that the downstream side is higher than the upstream side of the fuel flow, and an inlet side opening surface of the injection hole is opened on the step surface. The fuel injection valve according to claim 1, wherein
A fuel supply port that opens at a radially central portion of the fuel chamber and supplies fuel to the fuel chamber;
The fuel injection valve according to claim 1, wherein an inlet side opening surface of the injection hole opens radially outward with respect to an opening edge of the fuel supply port. The fuel injection valve according to claim 2,
A valve seat member formed with a conical surface constituting the valve seat and a cylindrical surface penetrating toward the tip end side in a direction along the central axis, an intermediate plate formed with the fuel supply port, and the injection hole; An injection hole plate formed with a bulging portion constituting the fuel chamber,
The fuel supply port has a circular opening surface that opens into the fuel chamber, and the radius of the cylindrical surface of the valve seat member is larger than the radius of the fuel supply port.
The intermediate plate and the injection hole plate are laminated so that the intermediate plate is positioned on the valve seat member side with respect to the injection hole plate, and joined to the end surface on the front end side of the valve seat member. Fuel injection valve. The fuel injection valve according to claim 3,
In the injection hole plate, an extension line extending virtually from the inner peripheral side portion to the outer peripheral side along the inner peripheral side portion with respect to the stepped surface intersects the inner wall surface of the injection hole. A fuel injection valve characterized by being configured.

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