JP2008298002A - Fuel injection nozzle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection nozzle capable of provide similar injection characteristics even if positions of injection holes provided on a nozzle body are different. <P>SOLUTION: The fuel injection nozzle 1 is provided with the nozzle body 3 having the injection hole 2a formed at a tip side, and a needle valve 4 reciprocating in the nozzle body 3. The nozzle body 3 has an injection hole open surface 3a reaching a predetermined zone where the injection hole 2a opens. The needle valve 4 includes a seat part 4a butting on a base end side of the injection hole open surface 3a and an opposing surface 4b arranged at a tip side of the seat part 4a and retained at roughly same distance from the injection hole open surface 3a. Namely, the fuel injection nozzle 1 is constructed to maintain a line segment included in the injection hole open surface 3a and a line segment included in the opposing surface 4b in a roughly parallel state when the needle valve 4 and the nozzle body 3 are sectioned in axial directions. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection nozzle for an internal combustion engine (engine).

  Conventionally, in a so-called direct-injection diesel engine, a needle valve incorporated in a nozzle body formed with a plurality of nozzle holes is seated on and separated from the seat surface of the nozzle body to execute fuel injection. A fuel injection nozzle for stopping is used. In such a fuel injection nozzle, a fuel reservoir chamber (sack part) is provided inside the tip of the nozzle body, and an MS (Mini Sac) nozzle for equalizing the fuel supplied to each nozzle hole, There is known a VCO (Valve Covered Orifice) nozzle that does not provide a fuel reservoir chamber on the inner side of the tip, and that directly executes and stops injection by opening and closing an injection hole by a needle valve.

  FIG. 7 is an explanatory view in which a part of the front end side of the MS nozzle is enlarged and taken as a cross section. The MS nozzle 100 is provided with a fuel reservoir chamber (sack portion) 102 on the inner side of the tip of the nozzle body 101, and an injection hole 103 is formed so that fuel is injected from the fuel reservoir chamber 102. In such an MS nozzle 100, the fuel reservoir chamber 102 and the nozzle hole 103 communicate with each other regardless of the open / closed state. When the needle valve 104 is separated, pressure is applied to the fuel accumulated in the fuel reservoir chamber 102, and the fuel The fuel accumulated in the reservoir chamber 102 is injected through the nozzle hole 103. In the MS nozzle 100, there is no significant change in the fuel flow due to the separation of the needle valve 104, and the fuel flow is stable, so that stable fuel injection can be executed. However, since the fuel reservoir chamber and the nozzle hole communicate with each other even when the needle is closed, the fuel accumulated in the fuel reservoir chamber 102 is injected even when the fuel is not injected due to a pressure change in the combustion chamber. May spill from. This outflow of fuel causes incomplete combustion particularly at low temperatures, and causes an increase in the HC (hydrocarbon) concentration of the exhaust gas.

  On the other hand, since the VCO nozzle 110 as shown in FIG. 8 blocks the inflow of fuel to the nozzle hole when the valve is closed, it is considered that the outflow of fuel unlike the MS nozzle 100 hardly occurs. As a variation of such a VCO nozzle, a VCO nozzle 120 with a groove 121 as shown in FIG. 11 has also been proposed. Further, various proposals such as Patent Document 1 have been made.

JP 11-336642 A

  Incidentally, as shown in FIG. 8, the VCO nozzle 110 has an injection hole 112a formed in the nozzle body 111. The nozzle hole 112a may vary in the drilling position due to a problem in processing accuracy. For example, the nozzle hole 112a may be drilled at the position of the nozzle hole 112b. That is, when the nozzle hole is drilled using a laser or a tool, it is difficult to form the nozzle hole at a position that is completely the same for processing accuracy, and a slight positional deviation occurs. When such injection hole variations occur, the following problems may occur. That is, the injection characteristics may be different between the nozzle hole 112b drilled on the distal end side and the nozzle hole 112a drilled on the proximal end side. The difference in the injection characteristics will be described with reference to FIGS. 9 (a) to 9 (b) and FIG. FIG. 9A shows the VCO nozzle 110 in the closed state, FIG. 9B shows the VOC nozzle 110 in the full lift state, FIG. 9C shows the VCO nozzle 110 in the state in which the valve moves to the closed state, and FIG. FIG. 10 is an explanatory view showing the VCO nozzle 110 in a valve-closed state as in FIG. Each figure is an explanatory view showing a part of the tip side of the VCO nozzle 110 as a cross section, and the shape of each part is exaggerated for convenience of explanation. FIG. 10 is a time-injection rate chart showing the transition of the injection rate corresponding to the state of the VCO nozzle 110 (FIGS. 9A to 9D).

  As shown in FIG. 9 (a), when the valve is closed, the injection rate is substantially 0 regardless of whether the nozzle hole 112a or the nozzle hole 112b. When the needle valve 113 starts to rise from this state, the injection rate varies depending on the position of the injection hole as shown in FIG. That is, the injection of the injection hole 112b located on the distal end side is started earlier than the injection of the injection hole 112a located on the proximal end side, and the injection rate of the injection hole 112b is high at the same time. Thereafter, when the full lift state is reached, the difference in the injection rate depending on the nozzle hole position is not observed, but after that, when going to the valve closing state, the difference in the injection rate is observed again. The difference in the injection rate is considered to be because the distance from the nozzle hole opening to the needle valve 113 is different. That is, it is considered that the distance S11 from the opening of the injection hole 112a to the needle valve 113 is different from the distance S12 from the opening of the injection hole 112b to the needle valve 113 as shown in FIG. Thus, if the position of the injection hole differs between products and the injection rate is different, the injection characteristics are affected. This is inconvenient because the fuel injection characteristics differ from product to product. For example, a setting derived using a certain fuel injection nozzle may not be applicable to other fuel injection nozzles having different injection hole positions.

  Even in the grooved VCO nozzle 120 provided with the groove 121 as shown in FIG. 11, the fuel injection characteristics are different if the injection hole drilling positions are different, and thus have the same problem.

  Therefore, an object of the present invention is to provide a fuel injection nozzle that can obtain the same injection characteristics even if the positions of the injection holes provided in the nozzle body are different.

  In order to solve this problem, a fuel injection nozzle according to the present invention includes a nozzle body having a nozzle hole formed on a tip end side thereof, and a needle valve that reciprocates within the nozzle body, and the nozzle body has an inner circumference. A nozzle hole opening surface over a predetermined region where the nozzle hole opens on the side, the needle valve being in contact with the proximal end side with respect to the nozzle hole opening surface, and on the distal end side with respect to the sheet portion It has an opposing surface arranged and maintained at a substantially equal distance from the nozzle hole opening surface (Claim 1). By adopting such a configuration, variations in fuel injection characteristics between products can be reduced. Here, the predetermined area may be an area that can cover a range in which variation occurs when the nozzle hole is formed. Such a nozzle hole opening surface and the opposing surface of the needle valve may be formed in a circumferential shape or may be formed over the entire circumference. If the distance between the nozzle hole opening surface and the opposed surface is substantially equal throughout the nozzle hole opening surface, the same injection characteristics can be maintained even if the nozzle hole positions vary. be able to. Here, “substantially equidistant” refers to a range in which similar injection characteristics can be obtained when injection holes are formed at different positions in the injection hole opening surface and fuel injection is performed.

  The opposed surface of such a fuel injection nozzle may be configured such that a concave portion is formed on the outer peripheral wall of the needle valve and provided on the bottom surface of the concave portion. The needle valve may be formed in a tapered shape at the tip rather than the seat portion, but even in such a case, if the concave portion is formed and the bottom surface of the concave portion is the opposing surface, The above relationship can be formed.

  Further, the nozzle hole opening surface may be configured such that a concave portion is formed on the inner peripheral surface of the nozzle body and the bottom surface of the concave portion is provided. Such a configuration can also form the above relationship with the nozzle hole opening surface.

  In such a fuel injection nozzle, it is desirable that a clearance between the nozzle hole opening surface and the facing surface when closing is narrower than a diameter dimension of the nozzle hole. By adopting such a configuration, variations in fuel injection characteristics can be further reduced.

  In such a fuel injection nozzle, when the needle valve and the nozzle body are sectioned in the axial direction, the line segment included in the nozzle hole opening surface and the line segment included in the facing surface are in a substantially parallel state. (Claim 5).

  According to the present invention, the opposing surface in which the distance between the nozzle body having a nozzle hole opening surface extending over a predetermined region where the nozzle hole opens on the inner peripheral side and the nozzle hole opening surface is maintained at substantially the same distance. The same injection characteristics can be obtained even if the positions of the injection holes provided in the nozzle body are different.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory view in which a part of the front end side of the fuel injection nozzle 1 of the present invention is enlarged and shown in cross section. FIG. 2 is an explanatory diagram further enlarging a region A indicated by a broken line in FIG. The fuel injection nozzle 1 includes a nozzle body 3 in which an injection hole 2a (or 2b) is formed on the distal end side, and a needle valve 4 that reciprocates within the nozzle body 3. The nozzle body 3 has a nozzle hole opening surface 3a extending over a predetermined region where a nozzle hole 2a (2b) having a diameter R is opened. The predetermined area of the nozzle hole opening surface 3a is not particularly partitioned by a step or the like, and forms a smooth aspect. On the other hand, the needle valve 4 is disposed closer to the base end side than the nozzle hole opening surface 3a and the tip side of the sheet part 4a, and the distance from the nozzle hole opening surface 3a is substantially equal. And an opposing surface 4b maintained at the same time. That is, when the needle valve 4 and the nozzle body 3 are cross-sectioned in the axial direction as shown in FIGS. 1 and 2, the fuel injection nozzle 1 has a line segment 3a1 included in the nozzle hole opening surface 3a and an opposing surface 4b. The included line segment 4b1 is in a substantially parallel state.

  Here, the opposing surface 3 a forms a recess 5 in the outer peripheral wall of the needle valve 4, and is provided on the bottom surface of the recess 5. 1 and 2 show the fuel injection nozzle 1 in a valve-closed state. In this state, the distance between the nozzle hole opening surface 3a and the opposing surface 4b is S1 regardless of the position of the nozzle hole opening surface 3a. It has become. The needle valve 4 in the closed state is adjusted so that only the seat portion 4a formed in a circumferential shape contacts the nozzle body 3 to seal the fuel. The distance S1 between the nozzle hole opening surface 3a and the facing surface 4b, that is, the clearance is narrower than the diameter dimension R of the nozzle hole 2a (2b).

  The fuel injection state of the fuel injection nozzle 1 configured as described above will be described with reference to FIGS. 3A is a fuel injection nozzle 1 in a valve-closed state, FIG. 3B is a fuel injection nozzle 1 in a full-lift state, FIG. 3C is a fuel injection nozzle 1 in a state of being shifted to a valve-closed state, FIG. (D) is explanatory drawing which showed the fuel-injection nozzle 1 of a valve closing state similarly to Fig.3 (a). In addition, each figure is explanatory drawing which showed the front end side part of the fuel-injection nozzle 1 as a cross section, and the shape of each part has the part drawn exaggerated on account of description. FIG. 4 is a time-injection rate chart showing the transition of the injection rate corresponding to the state of the fuel injection nozzle 1 (FIGS. 3A to 3D).

  As shown in FIG. 3 (a), when the valve is closed, the injection rate is substantially 0 regardless of whether the nozzle hole 2a or the nozzle hole 2b. From this state, the needle valve 4 rises. At this time, even if the positions of the nozzle holes are different, there is no significant difference in the injection rate. Thereafter, no difference in the injection rate depending on the nozzle hole position is observed even when the full lift state is reached. Furthermore, no significant difference is observed in the injection rate during the subsequent transition to the valve closing state. As described above, the fuel injection needle 1 of the present embodiment has a high injection rate because the distance between the nozzle hole opening surface 3a and the opposed surface 4b is maintained at approximately the same distance even when the nozzle holes are formed at different positions. There is no big difference, and it is possible to obtain injection characteristics with little variation between products.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is an explanatory view in which a part of the front end side of the fuel injection nozzle 11 of the present invention is enlarged and shown in cross section. 6A shows the fuel injection nozzle 11 in the valve-closed state, FIG. 6B shows the fuel injection nozzle 11 in the full-lift state, FIG. 6C shows the fuel injection nozzle 11 in the state of shifting to the valve-closed state, FIG. (D) is explanatory drawing which showed the fuel-injection nozzle 11 of a valve closing state similarly to Fig.6 (a). In addition, each figure is explanatory drawing which showed the front end side part of the fuel-injection nozzle 1 as a cross section, and the shape of each part has the part drawn exaggerated on account of description.

  The fuel injection nozzle 11 includes a nozzle body 13 having a nozzle hole 12a (or 12b) formed on the tip end side, and a needle valve 14 that reciprocates within the nozzle body 13. The nozzle body 13 has a nozzle hole opening surface 13a extending over a predetermined region where the nozzle holes 12a (12b) are opened. Here, the nozzle hole opening surface 13 a forms a recess 15 on the inner peripheral surface of the nozzle body 13, and is provided on the bottom surface of the recess 15. On the other hand, the needle valve 14 is disposed closer to the base end side than the nozzle hole opening surface 13a and the tip side of the sheet part 14a, and the distance from the nozzle hole opening surface 13a is substantially equal. And a facing surface 14b maintained at the same position. That is, when the needle valve 14 and the nozzle body 13 are sectioned in the axial direction as shown in FIGS. 5 and 6, the fuel injection nozzle 11 is formed on the line segment 13a1 and the opposing surface 4b included in the nozzle hole opening surface 13a. The included line segment 14b1 is in a substantially parallel state.

  5 and 6 show the fuel injection nozzle 11 in a valve-closed state. In this state, the distance between the nozzle hole opening surface 13a and the facing surface 14b is S1 regardless of the position of the nozzle hole opening surface 13a. It has become. When the valve is closed, the needle valve 14 is adjusted so that only the circumferentially formed seat portion 14a comes into contact with the nozzle body 13 to seal the fuel. The distance S1 between the nozzle hole opening surface 13a and the facing surface 4b, that is, the clearance is narrower than the diameter dimension of the nozzle hole 2a (2b).

  Similarly to the fuel injection nozzle 1 of the first embodiment, the fuel injection nozzle 11 having the above-described configuration can obtain fuel injection characteristics with less variation between products.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope. For example, a plurality of nozzle holes can be provided, or a plurality of nozzle holes can be arranged on the distal end side and the proximal end side.

It is explanatory drawing which expanded the front end side part of the fuel-injection nozzle of this invention, and made it the cross section. It is explanatory drawing which expanded and showed the area | region A shown with the broken line in FIG. 3 (a) is a fuel injection nozzle in a closed state, FIG. 3 (b) is a fuel injection nozzle in a full lift state, FIG. 3 (c) is a fuel injection nozzle in a state of shifting to a valve closed state, and FIG. 3 (d). Fig. 4 is an explanatory view showing a fuel injection nozzle in a valve-closed state as in Fig. 3 (a). It is the time-injection rate chart which showed transition of the injection rate corresponding to the state of the fuel injection nozzle. It is explanatory drawing which expanded the front end side part of the fuel-injection nozzle of another Example, and was made into the cross section. 6 (a) is a fuel injection nozzle in a closed state, FIG. 6 (b) is a fuel injection nozzle in a full lift state, FIG. 6 (c) is a fuel injection nozzle in a state of shifting to a valve closed state, and FIG. 6 (d). These are explanatory drawings which showed the fuel-injection nozzle of a valve closing state similarly to Fig.6 (a). It is explanatory drawing which expanded the front end side part of the conventional MS nozzle, and made it the cross section. It is explanatory drawing which expanded the front end side part of the conventional VCO nozzle, and made it a cross section. 9A is a VCO nozzle in a valve-closed state, FIG. 9B is a VOC nozzle in a full-lift state, FIG. 9C is a VCO nozzle in a state of shifting to a valve-closed state, and FIG. It is explanatory drawing which showed the VCO nozzle of a valve closing state similarly to (a). It is the time-injection rate chart which showed transition of the injection rate corresponding to the state of the VCO nozzle. It is explanatory drawing which expanded the front end side part of the conventional VCO nozzle with a groove, and made it the cross section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11 Fuel injection nozzle 2a, 12a, 2b, 12b Injection hole 3, 13 Nozzle body 3a, 13a Injection hole opening surface 4, 14 Needle valve 4a, 14a Seat part 4b, 14b Opposing surface 5, 15 Recess

Claims (5)

A nozzle body with a nozzle hole formed on the tip side;
A needle valve that reciprocates within the nozzle body,
The nozzle body has a nozzle hole opening surface over a predetermined region where the nozzle hole opens on the inner peripheral side,
The needle valve is disposed closer to the base end side than the nozzle hole opening surface and the tip side of the sheet part, and the distance between the nozzle hole opening surface is maintained at a substantially equal distance. A fuel injection nozzle having an opposing surface. The fuel injection nozzle according to claim 1.
The fuel injection nozzle according to claim 1, wherein the opposing surface is formed with a recess in an outer peripheral wall of the needle valve, and is provided on a bottom surface of the recess. The fuel injection nozzle according to claim 1.
The fuel injection nozzle according to claim 1, wherein the nozzle hole opening surface has a recess formed on an inner peripheral surface of the nozzle body and is provided on a bottom surface of the recess. The fuel injection nozzle according to claim 1.
A fuel injection nozzle, wherein a clearance between the nozzle hole opening surface and the facing surface when the valve is closed is narrower than a diameter dimension of the nozzle hole. The fuel injection nozzle according to claim 1.
A fuel injection nozzle characterized in that when the needle valve and the nozzle body are cross-sectioned in the axial direction, a line segment included in the nozzle hole opening surface and a line segment included in the facing surface are in a substantially parallel state.

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