JP2009002212A - Fuel injection nozzle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection nozzle with intensified penetration of fuel spray. <P>SOLUTION: A fuel injection nozzle 1 is provided with a nozzle body 50 including injection hole paths 30, 40 for injecting fuel, an outside needle 10 and an inside needle 20 held in a nozzle body 50, arranged doubly at an inside and an outside, and opening/closing the injection hole paths 30, 40. The injection hole paths 30, 40 include flow-in ports 31, 42, and flow-out ports 32, 42 formed at positions closer one another than the flow-in ports 31, 41, and are formed to keep direction of the flow-out ports 32, 42 mutually in parallel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection nozzle.

  2. Description of the Related Art Conventionally, a fuel injection nozzle used in an internal combustion engine has been known which has a plurality of injection hole paths in the axial direction in order to obtain atomization of fuel and penetration of spray (Patent Document 1 and Patent Document 1). 2). Such a fuel injection nozzle forms sprays by a plurality of nozzle hole paths, and can reduce the diameter of each nozzle hole path, thereby achieving atomization of fuel and spray injected from each nozzle hole path. The penetration force of the spray can be obtained by interfering with each other.

JP 2007-16773 A JP 2007-23969 A

  However, in order to make the penetration force of the spray strong, it is necessary that the distance between the outlets of each nozzle hole path is close and the directions of the outlets of each nozzle hole path are parallel. However, the distance between the inlets of the nozzle holes requires a certain distance due to the structure of the fuel injection nozzle. Even if the nozzle holes are formed in parallel while maintaining this distance, the outlets of the nozzle holes Since the distance between them is too far away, it is difficult to increase the penetration of the spray. Further, if only the outlets of the nozzle holes are brought close to each other, the direction of fuel ejection from the nozzle holes intersects, and in this case, it is difficult to increase the penetration force of the spray.

  Accordingly, an object of the present invention is to provide a fuel injection nozzle with enhanced penetration of fuel spray.

The above object is achieved by the nozzle body having the first and second nozzle holes for injecting the fuel, and being accommodated in the nozzle body and arranged in duplicate inside and outside the first and second nozzle paths. 1st and 2nd needle which opens and closes each, The said 1st and 2nd nozzle hole path is a position closer than the 1st and 2nd inlet, and between the 1st and 2nd inlet, respectively The first and second outlets formed in the first and second outlets are formed so that the directions of the first and second outlets are parallel to each other. .
With this configuration, the first and second outlets are formed at positions closer to each other than between the first and second inlets, and the respective directions of the first and second outlets are formed in parallel. Therefore, even when the first and second inlets are separated from each other, the penetration force of the spray can be increased.

Further, in the above configuration, the first and second nozzle holes are respectively arranged in a non-parallel section approaching from the first and second inlets to the middle position, and from the middle position to the first and second positions. A configuration including a parallel section that is parallel to the two outlets can be employed.
With this configuration, the penetration force of the spray can be increased.

Further, in the above configuration, at least one of the first and second nozzle holes is curved at the middle position, and a passage sectional area in the non-parallel section is larger than a passage sectional area in the parallel section. Can adopt the configuration.
With this configuration, at least one of the first and second nozzle holes has a passage cross-sectional area in the non-parallel section that is larger than a passage cross-sectional area in the parallel section. it can. As a result, the throttle resistance to the injected fuel is reduced and the pressure loss is reduced, so that the spray penetration force can be increased.

Further, in the above configuration, at least one of the first and second nozzle holes is curved at the middle position, and a passage sectional area in the non-parallel section is larger than a passage sectional area in the parallel section. The opening end of the inflow port corresponding to at least one of the first and second nozzle holes is formed so that the width in the circumferential direction is larger than the width in the radial direction of the nozzle body. Can adopt the configuration.
Even if it is a case where the channel | path cross-sectional area in a parallel area is enlarged by this structure, the sealing performance with respect to the inflow port can be maintained.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel-injection nozzle with which the penetration force of the spray of fuel was reinforced can be provided.

  Hereinafter, a fuel injection nozzle according to the present invention will be described with reference to the drawings.

  FIG. 1 is a partial cross-sectional view of the fuel injection nozzle 1. The fuel injection nozzle 1 is a nozzle that directly injects fuel into a cylinder of an internal combustion engine. The fuel pressurized by a fuel pump (not shown) is accumulated at a constant pressure in the common rail 80 and introduced into the fuel injection nozzle 1 provided in each cylinder. Of the introduced fuel, surplus fuel is returned to the fuel tank 82. As shown in FIG. 1, the fuel injection nozzle 1 includes an outer needle 10, an inner needle 20, a nozzle body 50, a sleeve 60, springs 98 and 99, and the like.

  The nozzle body 50 is formed in a substantially columnar shape, and the outer needle 10 and the inner needle 20 are disposed in a double manner in the nozzle body 50 so as to be reciprocally movable in the axial direction. The outer needle 10 is slid with the inner peripheral surface of a substantially cylindrical sleeve 60 disposed in the nozzle body 50 to restrict the reciprocating direction. The outer needle 10 is formed in a substantially cylindrical shape, and the inner needle 20 is accommodated so as to reciprocate in the axial direction when the outer peripheral surface of the inner needle 20 and the inner peripheral surface of the outer needle 10 slide. ing.

  The outer needle 10 is formed with a flange 12 protruding radially at an axial intermediate position, and a spring 98 is disposed between the flange 12 and the lower end of the sleeve 60. The spring 98 biases the outer needle 10 downward. In addition, a communication passage 11 is formed in the outer needle 10 below the flange 12. The communication path 11 has a function of guiding fuel around the outer peripheral portion of the outer needle 10 to the inner peripheral portion of the outer needle 10. Thereby, fuel is supplied between the inner peripheral surface of the outer needle 10 and the outer peripheral surface of the inner needle 20. At the lower end portion of the outer needle 10, a seal portion 13 that blocks or opens the ejection of fuel from the nozzle hole passage 30 is formed.

  The inner needle 20 includes, from the upper part to the lower part in the axial direction, a flange part 29, a large-diameter part 21 having a substantially cylindrical shape, a small-diameter part 22 having a smaller diameter than the large-diameter part 21, and a tip part 23 having a three-stage conical surface. Is formed. The lower end portion of the spring 99 is in contact with the flange portion 29, whereby the inner needle 20 is urged downward in the axial direction. The large diameter portion 21 slides with the inner peripheral surface of the outer needle 10. A fuel passage is secured between the small diameter portion 22 and the inner peripheral surface of the outer needle 10. Further, the distal end portion 23 has a seat portion 24 that comes into liquid-tight contact with the seat portion of the seat surface 51 and blocks or opens the ejection of fuel from the nozzle hole passage 40. The outer needle 10, the inner needle 20, and the nozzle body 50 are made of a metal material such as carbon steel.

  The nozzle body 50 is formed with a nozzle surface 30 and 40 for injecting fuel into a cylinder (not shown) of the internal combustion engine, and a seat surface 51 for seating the tip portion 23 at the lower end. The nozzle holes 30 and 40 are respectively formed in an upper stage and a lower stage in the axial direction, and a plurality of nozzle passages 30 and 40 are formed along concentric circles having different diameters with the central axis of the nozzle body 50 as the center. Further, the same number of nozzle holes 30 and 40 are provided so as to be aligned in the axial direction. The nozzle hole path 30 is formed outside the nozzle hole path 40. Further, a fuel supply passage 71 and a return passage 72 are formed between the nozzle body 50 and the outer peripheral surface of the sleeve 60 and the outer peripheral surface of the outer needle 10, and the fuel supply passage 71 is a high pressure supplied from the common rail 80. It becomes a fuel passage. The return passage 72 is a passage for returning surplus fuel that has not been used for fuel injection to the fuel tank 82. The fuel in the fuel supply path 71 flows into the return path 72 via the communication path 11.

  Further, the fuel in the fuel supply path 71 flows into the pressure control chamber 73 defined by the inner peripheral surface of the sleeve 60 through the throttle path 61. Although not shown, the pressure control chamber 73 is also provided with a return passage for returning surplus fuel to the fuel tank 82. The amount of fuel returned to the fuel tank 82 via this return passage is adjusted by the pressure regulator 81. The pressure regulator 81 is an electromagnetic valve that opens and closes in response to a command from an ECU (not shown). Note that the pressure of the fuel flowing into the pressure control chamber 73 acts to urge the outer needle 10 and the inner needle 20 downward.

  Next, the operation of the fuel injection nozzle 1 will be briefly described. First, a state where fuel injection is stopped will be described. The pressure in the pressure control chamber 73 becomes the same as the pressure in the common rail 80 by blocking the return passage for returning the fuel from the pressure control chamber 73 to the fuel tank 82 by the pressure regulator 81. Thereby, the outer needle 10 and the inner needle 20 are urged downward, and the seal portion 13 and the seat portion 24 are maintained in a state where they are seated on the seat surface 51.

  Next, an operation for opening the nozzle hole passage 30 will be described. In response to an instruction from the ECU, when the pressure adjusting device 81 opens a return passage where the pressure control chamber 73 and the fuel tank 82 communicate with each other, the fuel in the pressure control chamber 73 is returned to the fuel tank 82. As a result, the fuel pressure in the pressure control chamber 73 decreases. Due to the decrease in the fuel pressure, the outer needle 10 is lifted, and the seal portion 13 is separated from the seat surface 51. Thereby, the nozzle hole path 30 is opened and fuel is injected. Even if the fuel pressure in the pressure control chamber 73 decreases, the fuel flowing into the pressure control chamber 73 is throttled by the throttle path 61, so that the fuel pressure in the pressure control chamber 73 does not increase immediately.

  Next, an operation for opening the nozzle hole passage 40 will be described. When the fuel pressure in the pressure control chamber 73 further decreases than in the case described above, the inner needle 20 is lifted and the seat portion 24 is separated from the seat surface 51. Thereby, the nozzle hole path 40 is opened and fuel is injected.

  Next, an operation for stopping fuel injection will be described. When the pressure regulating device 81 closes the return passage communicating with the pressure control chamber 73 according to an instruction from the ECU, the pressure in the pressure control chamber 73 increases and matches the pressure in the common rail 80. In this process, the outer needle 10 and the inner needle 20 move downward, and the seal portion 13 and the seat portion 24 are seated on the seat surface 51 almost simultaneously. Thereby, the nozzle hole paths 30 and 40 are shut off, and fuel injection is stopped.

Next, the nozzle hole paths 30 and 40 will be described in detail.
FIG. 2 is an enlarged view around the nozzle hole paths 30 and 40. In FIG. 2, the inner needle 20 is not shown. FIG. 2 shows a state in which the outer needle 10 is lifted upward to open the nozzle hole passage 30.

  The nozzle hole path 30 has an inflow port 31 opened in the sheet surface 51 and an outflow port 32 opened in the outer peripheral surface of the nozzle body 50. Further, the nozzle hole path 30 is formed in a straight line from the inlet 31 to the middle part 33 at an acute angle with respect to the axial direction. Further, the nozzle hole path 30 curves at the middle part 33 and has a gentle inclination with respect to the horizontal direction, extends linearly outward in the radial direction, and communicates with the outlet 32.

  The nozzle hole path 40 has an inflow port 41 opened in the sheet surface 51 and an outflow port 42 opened in the outer peripheral surface of the nozzle body 50. The nozzle hole path 40 is formed in a straight line from the inlet 41 to the outlet 42.

  As shown in FIG. 2, when comparing the distance A between the inlets 31 and 41 and the distance B between the outlets 32 and 42, the distance B between the outlets is closer than the distance A between the inlets. It turns out that it is a distance. Further, the direction from the inlet 31 to the middle abdomen 33 and the direction from the inlet 41 to the middle abdomen 43 are not parallel as shown in FIG. 2 (this section is referred to as a non-parallel section l). In addition, the direction from the middle abdomen 33 to the outlet 32 and the direction from the middle abdomen 43 to the outlet 42 are formed in parallel (this section is referred to as a parallel section L). Since the nozzle passages 30 and 40 each have a parallel section L, the fuel injection directions from the outlets 32 and 42 are parallel to each other.

  As described above, the outlets 32 and 42 are formed at close positions, and the directions of the outlets 32 and 42 are substantially parallel, so that the fuel sprays from the outlets 32 and 42 interfere with each other. Spray penetration can be strengthened. Moreover, since the inflow ports 31 and 41 can be formed at positions separated from each other, for example, in consideration of the structure of the outer needle 10 and the inner needle 20 or the sealing performance of the inflow ports 31 and 41, etc. Even if it is difficult to form the inflow ports 31 and 41 at close positions, the penetration force of the spray can be increased.

  As shown in FIG. 2, the cross-sectional area of the nozzle hole path 30 in the non-parallel section l is formed larger than the cross-sectional area of the nozzle hole path 30 in the parallel section L. This is because if the section having a small cross-sectional area is long, the throttle resistance against the fuel passing through the section increases, and the pressure loss may increase. However, as shown in FIG. 2, by increasing the cross-sectional area of the nozzle hole 30 on the inlet 31 side and reducing it on the outlet 32 side, pressure loss can be reduced and spray penetration can be maintained. it can.

Next, the seal part 13 will be described in detail.
The seal portion 13 includes an upper seal portion 13a and a lower seal portion 13b, has a so-called double seal structure, and is formed so as to be able to seal the entire opening end portion of the inflow port 31. The upper seal portion 13a and the lower seal portion 13b form a substantially annular groove at the tip of the outer needle 10 that can face the inflow port 31. When the seal portion 13 is seated on the seat surface 51, fuel leakage from the nozzle hole passage 30 is prevented.

Next, processing of the nozzle hole path 30 will be briefly described.
FIG. 3 is an explanatory diagram regarding the processing of the nozzle hole passage 30.
In order to process the nozzle hole path 30, the nozzle body 50 is fixed by a jig and formed by electric discharge machining. Specifically, the non-parallel section l is formed from the inner peripheral surface of the nozzle body 50 in the direction of the arrow D shown in FIG. The parallel section L is formed from the outer peripheral surface of the tip end portion of the nozzle body 50. At this time, as described above, the cross-sectional area in the non-parallel section l is formed to be larger than the cross-sectional area in the parallel section L.

  Further, the shape of the opening end of the inlet 31 is processed into an elliptical shape so that the width a in the circumferential direction of the nozzle body 50 is larger than the width b in the radial direction of the nozzle body 50. The shape of the opening end of the inflow port 31 is also performed by electric discharge machining. 3 is a cross-sectional view taken along the line AA showing the shape of the opening end of the inflow port 31.

  By processing the shape of the opening end portion of the inflow port 31 in this way, the sealing performance by the seal portion 13 can be maintained while maintaining the size of the opening end area of the inflow port 31. That is, considering the sealing performance by the seal portion 13, the distance between the upper seal portion 13a and the lower seal portion 13b is short, and the width b of the nozzle body 50 in the radial direction of the nozzle body 50 so as to correspond to this distance. The narrower the better. However, the width a of the inlet 31 in the circumferential direction of the nozzle body 50 does not depend on the distance between the upper seal portion 13a and the lower seal portion 13b. Therefore, by processing the shape of the opening end portion of the inflow port 31 in this way, the passage cross-sectional area in the non-parallel section l of the nozzle hole passage 30 can be secured, and the sealing performance can also be maintained.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

It is a fragmentary sectional view of a fuel injection nozzle. It is an enlarged view of a nozzle hole periphery. It is explanatory drawing about the process of a nozzle hole path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection nozzle 10 Outer needle 13 Seal part 13a Upper seal part 13b Lower seal part 20 Inner needle 30 Injection hole path 40 Injection hole path 31,41 Inlet 32,42 Outlet 50 Nozzle body 51 Seat surface

Claims (4)

A nozzle body having first and second nozzle holes for injecting fuel;
A first needle and a second needle which are accommodated in the nozzle body and are arranged double inside and outside to open and close each of the first and second nozzle holes;
Each of the first and second nozzle holes includes a first and a second inlet, and a first and a second outlet formed at a position closer to each other than between the first and the second inlets. In addition, the fuel injection nozzle is formed so that the directions of the first and second outlets are parallel to each other.   The first and second nozzle passages are respectively a non-parallel section approaching from the first and second inlets to the middle position, and from the middle position to the first and second outlets. The fuel injection nozzle according to claim 1, comprising a parallel section that is parallel.   At least one of the first and second nozzle holes is curved at the middle position, and a passage sectional area in the non-parallel section is larger than a passage sectional area in the parallel section. The fuel injection nozzle according to claim 2. At least one of the first and second nozzle holes is curved at the middle position, the passage cross-sectional area in the non-parallel section is formed larger than the passage cross-sectional area in the parallel section,
The opening end of the inflow port corresponding to at least one of the first and second nozzle holes is formed so that the width in the circumferential direction is larger than the width in the radial direction of the nozzle body. The fuel injection nozzle according to claim 2.

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