JP2016113983A - Fuel injection nozzle and fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection nozzle which can reduce a variation of injection amounts or injection speeds of fuel in a plurality of injection holes even if assembled obliquely, and can be easily designed in an optimum layout related to injection dispersion performance, and a fuel injection valve.SOLUTION: A sack chamber 100 in which fuel is accumulated is formed at a nozzle tip 18 by being surrounded by an inner wall 92 of a nozzle body 12 and an outer wall 94 of a needle valve 14. The sack chamber 100 includes a first space 102 located at a value head 90 side, and a second space 104 which makes the first space 102 communicate with the respective injection holes 22. The second space 104 extends along an inclined axis B which is inclined to a moving axis A, and the injection holes 22 are extended to angular directions (penetration directions D1, D2) having the same angles (injection angles φ) between the inclined axis B.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fuel injection nozzle that injects fuel from a plurality of injection holes, and a fuel injection valve including the fuel injection nozzle.

  Conventionally, a fuel injection nozzle that supplies high-pressure fuel into a fuel chamber of an engine by injecting fuel from a plurality of injection holes, and a fuel injection valve including the fuel injection nozzle have been developed. For example, in a direct injection type diesel engine, a fuel injection valve may be assembled in a state where the center line of the fuel injection nozzle is inclined with respect to the cylinder axis of the engine. For this reason, various techniques have been proposed for making the fuel injection amount or injection speed from each nozzle hole substantially constant regardless of the inclined state of the fuel injection nozzle.

  Patent Document 1 proposes a fuel injection nozzle that has a plurality of injection holes having different inclination angles with respect to the nozzle center line and that eccentrically displaces the needle valve on the opposite side of the nozzle inclination direction when the needle valve moves. . In addition, paragraph [0018] of the same document describes that the nozzle holes are provided at different angles in order to make the height positions of the points where the sprays reach approximately equal.

JP-A-11-093804 (Claim 1, FIG. 3, [0018])

  However, in the nozzle described in Patent Document 1, it is necessary to simultaneously adjust not only the inclination angle of the fuel injection nozzle but also the eccentric angle of the needle valve in order to equalize the injection amount. That is, there is a problem that if the accuracy control at both angles becomes loose, the variation in the injection amount and the like increases, while if the accuracy control becomes severe, the manufacturing cost increases.

Further, there is a problem that optimization of injection dispersion becomes difficult as the variation in the injection amount increases. Here, “injection dispersibility” means an injection characteristic in which fuel is evenly distributed in a specific space.

  The present invention has been made in view of the above-described problems, and can reduce the variation in the fuel injection amount or the injection speed between the plurality of injection holes, even when assembled with an inclination. An object of the present invention is to provide a fuel injection nozzle and a fuel injection valve capable of easily performing an optimization design regarding dispersibility.

  The fuel injection nozzle according to the present invention includes a nozzle body in which a plurality of injection holes for injecting fuel are formed on a distal end side, and the injection hole accommodated in the nozzle body and reciprocating along a movement axis. A sac chamber in which the fuel is accumulated at the tip end side of the nozzle body by being surrounded by an inner wall of the nozzle body and an outer wall of the needle valve. The sac chamber is formed to include a first space portion located on the tip side of the needle valve, and a second space portion that communicates the first space portion with each of the nozzle holes, and the second space. The portion extends along an inclination axis that is inclined with respect to the movement axis, and each nozzle hole is formed to extend in an angular direction having an equal angle with the inclination axis.

  As described above, the second space portion constituting a part of the sac chamber extends along the inclined axis inclined with respect to the moving axis of the needle valve, and the angle formed with the inclined axis is in an equal angular direction. Since a plurality of nozzle holes are formed by extending, the inlet angles of the nozzle holes are equal to each other, and the fuel flow characteristics in the vicinity of the nozzle holes are isotropic and substantially uniform. Thereby, even if it is a case where a fuel-injection nozzle is inclined and assembled | attached, the dispersion | variation in the injection quantity or injection speed of the fuel between several nozzle holes can be reduced. In particular, when the fuel injection nozzle is assembled with the tilt axis aligned with a specific direction (for example, the axial direction of the engine cylinder), the injection angle with respect to the specific direction is set to be the same. Can be executed easily.

  Moreover, it is preferable that the second space portion has a tapered shape that gradually decreases in diameter toward the tip end side of the nozzle body. By forming each nozzle hole penetrating in an oblique direction with respect to the tilt axis, the fuel present in the second space can be smoothly supplied to each nozzle hole.

  Moreover, it is preferable that all the said nozzle holes are formed with the same length. As a result, the path lengths passing through the respective nozzle holes are equal to each other, so that the fuel injection timings from the respective nozzle holes can be synchronized.

  The fuel injection valve according to the present invention includes any one of the fuel injection nozzles described above.

  According to the fuel injection nozzle and the fuel injection valve according to the present invention, even when the fuel injection nozzle and the fuel injection valve are assembled at an inclination, it is possible to reduce the variation in the fuel injection amount or the injection speed between the plurality of injection holes and Optimization design can be easily executed.

It is a perspective view of the fuel injection nozzle concerning this embodiment. It is sectional drawing of the fuel injection valve incorporating the fuel injection nozzle of FIG. It is a partial expanded sectional view of the nozzle tip part shown in FIG. It is a partial expanded sectional view at the time of attaching the fuel injection valve of FIG. 2 inclining. It is a partial expanded sectional view of the fuel-injection nozzle which concerns on a modification.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a fuel injection nozzle according to the present invention will be described with reference to the accompanying drawings by giving preferred embodiments in relation to a fuel injection valve.

[Configuration of Fuel Injection Nozzle 10 and Fuel Injection Valve 30]
FIG. 1 is a perspective view of a fuel injection nozzle 10 according to this embodiment. FIG. 2 is a cross-sectional view of the fuel injection valve 30 incorporating the fuel injection nozzle 10 of FIG. The fuel injection valve 30 is a device that injects high-pressure fuel into the cylinder of the engine, and is applied to, for example, a common rail direct injection system in a diesel engine.

  As shown in FIGS. 1 and 2, the fuel injection nozzle 10 basically includes a substantially cylindrical nozzle body 12 and a needle-like needle valve 14.

  The nozzle body 12 includes a nozzle cylinder portion 16 whose outer shape is substantially cylindrical, a nozzle distal end portion 18 located on the distal end side of the nozzle cylinder portion 16, and a nozzle proximal end portion 20 located on the proximal end side of the nozzle cylinder portion 16. And have. The nozzle tip 18 is substantially conical, and a plurality (four in this example) of nozzle holes 22 are formed on the outer peripheral surface of the nozzle tip 18. The nozzle base end portion 20 has a flange shape projecting radially outward with respect to the outer peripheral surface of the nozzle cylinder portion 16, and has a circular base end surface 23.

  A guide hole 24 having a circular cross section is formed in the center of the base end surface 23 along the axis of the nozzle body 12. The needle valve 14 is inserted in the guide hole 24 of the nozzle body 12 and can reciprocate along the movement axis A. A passage hole 26 having a circular cross section is formed at the peripheral edge of the base end face 23. The guide hole 24 and the passage hole 26 communicate with each other inside the nozzle body 12 (specifically, near the boundary between the nozzle cylinder portion 16 and the nozzle base end portion 20). In this case, the gap between the needle valve 14 and the guide hole 24 functions as a supply flow path 28 for supplying fuel from the passage hole 26 to each nozzle hole 22.

  As shown in FIG. 2, in addition to the fuel injection nozzle 10 described above, the fuel injection valve 30 includes a substantially cylindrical housing 32, a fuel introduction cylinder 34 provided obliquely with respect to the axis of the housing 32, and a housing And a magnet portion 36 provided along the axis of 32.

  The fuel injection nozzle 10 is fixed to the distal end side of the housing 32 via a trumpet-shaped retaining nut 38. A circular insertion hole 42 that is slightly larger than the cross-sectional diameter of the nozzle cylinder portion 16 is formed in the bottom portion 40 of the retaining nut 38. That is, the fuel injection nozzle 10 is attached to the housing 32 by inserting the nozzle cylinder portion 16 into the insertion hole 42 and screwing the retaining nut 38 to the distal end side of the housing 32.

  Inside the housing 32 are a valve piston 44 that contacts the proximal end side of the needle valve 14, a nozzle side coil spring 45 that is wound around the distal end side of the valve piston 44 and biases the needle valve 14 downward, and a valve A valve body 46 that slidably engages the valve piston 44 on the proximal end side of the piston 44, an armature portion 47 that contacts the proximal end side of the valve body 46, and a guide portion 48 that guides the armature portion 47. Contained. A control chamber 50 having a space for filling fuel is formed on the base end side of the valve piston 44.

  The valve body 46 includes a bottomed cylindrical valve cylinder portion 52, a flange portion 54 that protrudes radially outward, and a concave portion 56 that is tapered on the upper surface of the flange portion 54. A ball 58 constituting a part of the armature portion 47 is seated on the bottom of the recess 56. The guide portion 48 abuts on the upper surface side of the flange portion 54.

  A first orifice 60 that extends in the axial direction from the control chamber 50 and a second orifice 62 that extends in the radial direction from the control chamber 50 are formed in the valve body 46. As a result, the control chamber 50 communicates with the space on the concave portion 56 side via the first orifice 60 and also communicates with a second passage hole 78 described later via the second orifice 62.

  Inside the magnet portion 36, a valve-side coil spring 66 that biases the armature portion 47 downward and an annular magnet 68 that surrounds the valve-side coil spring 66 are further accommodated. The valve-side coil spring 66 and the magnet 68 move the armature portion 47 along the axial direction of the valve-side coil spring 66 in accordance with the magnitude of current supplied to the magnet 68 via an electrical connector 80 described later. It functions as an electromagnetic actuator 70 to be activated.

  On the peripheral side of the housing 32, a first passage hole 74 that allows the introduction port 72 of the fuel introduction cylinder 34 to communicate with the passage hole 26 of the nozzle body 12, and a second passage hole that branches off from the branch portion 76 of the first passage hole 74. 78 is formed. The second passage hole 78 communicates with the second orifice 62 of the valve body 46.

  The magnet unit 36 further includes an electrical connector 80 for electrical connection with an electronic control unit (hereinafter referred to as ECU) (not shown), and a discharge port 82 communicating with the inside of the housing 32.

[Operation of Fuel Injection Valve 30]
Next, the operation of the fuel injection valve 30 will be described with reference to FIG. The fuel injection valve 30 performs an injection operation of the fuel introduced from the introduction port 72 in accordance with a control signal from an ECU (not shown) connected via the electrical connector 80.

  First, when the electromagnetic actuator 70 is not energized, the armature portion 47 is urged and pressed downward by the valve side coil spring 66, so that one end of the first orifice 60 is closed by the ball 58. Become. At this time, the fuel from the introduction port 72 is introduced into the control chamber 50 through the branch portion 76, the second passage 78, and the second orifice 62, and stored in the control chamber 50. At the same time, the fuel from the inlet 72 is stored in the supply flow path 28 through the branch portion 76, the first passage 74 and the passage hole 26.

  The valve piston 44 is biased upward via the nozzle body 12 by the pressure of the fuel accumulated in the supply flow path 28. On the other hand, the valve piston 44 is urged downward by the pressure of the fuel stored in the control chamber 50 and the elastic force of the nozzle side coil spring 45.

  In this state, the lower urging force has a larger relationship than the upper urging force. The valve piston 44 is moved downward, and the needle valve 14 is moved downward in conjunction with the valve piston 44. As a result, the fuel supply flow path 28 is shut off, so that fuel is not injected from each nozzle hole 22.

  Second, when the electromagnetic actuator 70 is energized, the valve-side coil spring 66 is contracted against the elastic force of the valve-side coil spring 66 due to the generation of electromagnetic force. The release of the bias by the valve side coil spring 66 moves the armature portion 47 including the ball 58 upward, so that the first orifice 60 is opened. At this time, the fuel stored in the control chamber 50 is discharged to the outside of the fuel injection valve 30 through the first orifice 60, the recess 56 and the discharge port 82.

  By reducing the pressure receiving in the control chamber 50, the lower biasing force is smaller than the upper biasing force, contrary to the above-described relationship. Then, the valve piston 44 is moved upward, and the needle valve 14 is moved upward in conjunction with the valve piston 44. By this movement, the fuel supply flow path 28 is opened, so that fuel is injected from each nozzle hole 22. Specifically, the fuel from the inlet 72 is discharged from the fuel injection valve 30 through the branch portion 76, the first passage 74, the passage hole 26, the supply passage 28, and each injection hole 22.

  As described above, the fuel injection valve 30 repeats the reciprocating operation along the movement axis A of the needle valve 14 to sequentially inject a high-pressure fuel supplied from a common rail (not shown) by a desired injection amount at a desired timing. To do.

[Structural Features of Fuel Injection Nozzle 10]
Subsequently, structural features of the fuel injection nozzle 10 will be described with reference to FIGS. 3 and 4. FIG. 3 is a partially enlarged sectional view of the nozzle tip 18 shown in FIG. More specifically, FIG. 3A is a diagram when fuel is injected, and FIG. 3B is a diagram when fuel is not injected. In either figure, the positional relationship between the nozzle tip 18 of the nozzle body 12 and the valve head 90 of the needle valve 14 is schematically shown.

As shown in FIG. 3A, the inner wall 92 of the nozzle tip 18 does not contact the outer wall 94 of the valve head 90. Thereby, the supply flow path 28 is opened and fuel is supplied to each nozzle hole 22. Hereinafter, among the two nozzle holes 22 shown in the figure, the left side is referred to as a nozzle hole 22a and the right side is referred to as 22b, and these may be described separately as necessary.

  As shown in FIG. 3B, the valve head 90 and the nozzle tip 18 are in partial contact, and the valve head 90 is seated on the seat portion 96 of the inner wall 92. Thereby, the supply flow path 28 is interrupted and the supply of fuel to each nozzle hole 22 is stopped.

  As shown in FIGS. 3A and 3B, a sac chamber 100 in which fuel is accumulated at the nozzle tip 18 is formed by being surrounded by the inner wall 92 of the nozzle body 12 and the outer wall 94 of the needle valve 14. The sac chamber 100 includes a first space portion 102 located on the distal end side (the periphery of the valve head 90) of the needle valve 14 and a second space portion 104 that allows the first space portion 102 to communicate with each nozzle hole 22. Composed.

  The first space 102 has a substantially truncated cone shape in the state of FIG. The second space portion 104 has a tapered shape (conical shape in this example) that gradually decreases in diameter toward the tip end side of the nozzle body 12. The second space 104 extends along an inclination axis B that is inclined with respect to the movement axis A by a predetermined angle (hereinafter referred to as an inclination angle θ). This inclination angle θ (unit: degree) corresponds to an assembly angle of the fuel injection valve 30 with respect to the engine, as will be described later. The inclination angle θ may take an arbitrary value other than 0 degrees, and specifically may be set as 0 <θ ≦ 45.

  The nozzle hole 22a is a hole penetrating along the penetrating direction D1, and has a length d1. The nozzle hole 22b is a hole that penetrates along the penetration direction D2, and has a length of d2. As can be understood from this figure, the angle formed between the tilt axis B and the penetrating direction D1 (hereinafter, injection angle φ) is equal to the angle formed between the tilt axis B and the penetrating direction D2. The injection angle φ (unit: degree) may take an arbitrary value other than 0 degrees, and specifically may be set as 0 <φ ≦ 60.

  That is, the nozzle holes 22a and 22b are formed so as to extend in an angular direction (penetration directions D1 and D2) where the angle (injection angle φ) formed with the tilt axis B is within an allowable range (so-called tolerance range). Here, “within the allowable range” means that the absolute value of the angle difference is equal to or less than a threshold value (for example, 5 degrees or 3 degrees). The remaining two nozzle holes 22 not shown satisfy the same angular relationship.

  Further, since the second space 104 has a symmetrical shape with respect to the tilt axis B, the inlet angles of the nozzle holes 22a and 22b are equal to each other. Here, the “inlet angle” is an angle formed by the formation surface of the nozzle hole 22 (here, the inner wall surface of the second space portion 104) and the penetrating direction, and is closer to the upstream side of the supply flow path 28. Means the corner.

  FIG. 4 is a partially enlarged cross-sectional view when the fuel injection valve 30 of FIG. 2 is assembled at an inclination. In the illustrated example, a state in which the fuel injection valve 30 (fuel injection nozzle 10) is inclined by the inclination angle θ with respect to the axis of the engine cylinder 106 (hereinafter, cylinder axis C) is depicted. That is, the tilt axis B of the fuel injection nozzle 10 is configured to coincide with the cylinder axis C by assembling the fuel injection valve 30 at a predetermined position of the engine.

  The nozzle holes 22a and 22b are formed so as to extend in an angular direction (penetration directions D1 and D2) having the same angle (injection angle φ) with the tilt axis B, and are arranged symmetrically with respect to the tilt axis B. Yes. By making the inlet angles of the nozzle holes 22a and 22b equal to each other, the fuel flow characteristics in the vicinity of the inlet become isotropic and substantially uniform. Thereby, the dispersion | variation in the injection quantity or injection speed of a fuel can be reduced.

It should be noted that the fuel injection valve 30 is optimally designed in consideration of the structure or performance of the engine. Specifically, the same injection angle (φ) from a line-symmetric position with respect to the cylinder axis C, respectively.
Therefore, the optimization design for evenly distributing the fuel in the chamber 108 of the engine cylinder 106 can be easily executed. With this design, knocking suppression and combustion efficiency can be improved.

  In addition to or separately from this, the second space portion 104 may have a tapered shape that gradually decreases in diameter toward the distal end side of the nozzle body 12. By forming each nozzle hole 22a, 22b penetrating in an oblique direction (through direction D1, D2) with respect to the tilt axis B, the fuel existing in the second space 104 is smoothly directed toward each nozzle hole 22a, 22b. Can supply.

[Effects of the fuel injection nozzle 10]
As described above, the fuel injection nozzle 10 includes the nozzle body 12 in which the plurality of injection holes 22 for injecting the fuel are formed in the nozzle tip 18, the nozzle body 12, and the movement axis A. The needle valve 14 is provided to open or shut off the fuel supply passage 28 communicating with the nozzle hole 22 by the reciprocal movement. The fuel injection valve 30 includes the fuel injection nozzle 10 described above.

  A sac chamber 100 in which fuel is accumulated at the nozzle tip 18 is formed by being surrounded by the inner wall 92 of the nozzle body 12 and the outer wall 94 of the needle valve 14, and this sac chamber 100 is located on the valve head 90 side. The first space portion 102 and the second space portion 104 that allows the first space portion 102 to communicate with each nozzle hole 22 are configured. Further, the second space portion 104 extends along an inclination axis B that is inclined with respect to the movement axis A, and each nozzle hole 22 has an angle direction (injection angle φ) formed with the inclination axis B that is equal ( It is formed extending in the penetration direction D1, D2).

  With this configuration, the inlet angles of the injection holes 22 are equal to each other, and the fuel flow characteristics in the vicinity of the injection holes 22 are isotropic and substantially uniform. Thereby, even if it is a case where the fuel injection nozzle 10 is inclined and assembled, the dispersion | variation in the injection quantity or injection speed of the fuel between the some injection holes 22 can be reduced. In particular, when the fuel injection nozzle 10 (or the fuel injection valve 30) is assembled with the tilt axis B aligned with the cylinder axis C, the injection angle φ with respect to the cylinder axis C is set to be the same. Optimization design can be easily executed.

[Modification]
FIG. 5 is a partially enlarged cross-sectional view of a fuel injection nozzle 110 according to a modification. The fuel injection nozzle 110 is incorporated in the fuel injection valve 30 of FIG. 2 as in the case of the above-described embodiment (fuel injection nozzle 10).

  The fuel injection nozzle 110 is different from the fuel injection nozzle 10 of FIG. 3 in that a part of the nozzle tip 18 (hereinafter referred to as a cutting part 112) is cut. Due to the presence of the cutting portion 112, a nozzle hole 22c having a length different from that of the nozzle hole 22b (FIG. 3) is formed. The nozzle hole 22c is a hole penetrating along the penetrating direction D2, and has a length d1.

  Thus, each nozzle hole 22a, 22c may be formed with the same length. Since the path lengths (d1) passing through the nozzle holes 22a and 22c are equal to each other, the timing of fuel injection from the nozzle holes 22a and 22c can be synchronized.

[Remarks]
Note that the present invention is not limited to the above-described embodiments and modifications, and can of course be freely changed without departing from the gist of the present invention.

In this embodiment, four nozzle holes 22 are formed on the outer peripheral surface of the nozzle tip 18, but the number or arrangement of the nozzle holes 22 is not limited to this. The number of nozzle holes 22 may be two, three, or five or more.

  In this embodiment, the second space portion 104 has a tapered shape, but any shape extending along the tilt axis B may be adopted. Needless to say, the shape of the first space 102 is not limited to the approximate truncated cone.

DESCRIPTION OF SYMBOLS 10, 110 ... Fuel injection nozzle 12 ... Nozzle body 14 ... Needle valve 18 ... Nozzle tip part 22, 22a, 22b, 22c ... Injection hole 28 ... Supply flow path 30 ... Fuel injection valve 90 ... Valve head 92 ... Inner wall 94 ... Outer wall 100 ··· Sack chamber 102 ··· First space portion 104 ··· Second space portion A · · · Movement axis B · Inclination axis D1 and D2 · Through direction

Claims (4)

A nozzle body in which a plurality of nozzle holes for injecting fuel are formed on the tip side;
A needle valve that is housed in the nozzle body and that opens or shuts off the fuel supply flow path leading to the nozzle hole by reciprocating movement along a movement axis;
By being surrounded by the inner wall of the nozzle body and the outer wall of the needle valve, a sac chamber in which the fuel is accumulated is formed on the tip side of the nozzle body,
The sac chamber is configured to include a first space portion located on the tip side of the needle valve, and a second space portion that communicates the first space portion with each of the nozzle holes,
The second space portion extends along an inclination axis that is inclined with respect to the movement axis,
Each of the nozzle holes is formed to extend in an angular direction in which an angle formed with the inclined axis is equal.   2. The fuel injection nozzle according to claim 1, wherein the second space portion has a tapered shape that gradually decreases in diameter toward a tip end side of the nozzle body.   The fuel injection nozzle according to claim 1, wherein each of the injection holes is formed with the same length.   A fuel injection valve comprising the fuel injection nozzle according to claim 1.

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