JP4217231B2 - Fuel injection device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection device for an internal combustion engine.

  As a conventional fuel injection device, a cylindrical cover is disposed opposite to a front end surface of a valve body housing in which an injection hole is opened. One end of the cover opens on the front end surface of the cover, and the other end is an injection of the valve body housing. An air-fuel mixture forming hole that can be opened corresponding to the hole and into which the tip of the needle part of the valve body can be inserted, and one end that opens to the air-fuel mixture forming hole and the other end that opens to the front end surface or the outer peripheral surface of the cover Some have a suction passage (see, for example, Patent Document 1). In addition, there is a structure in which a cylindrical annular wall portion is provided in a downstream portion of a nozzle for injecting fuel so as to form an opening space and communicate with the combustion chamber through the opening space (see, for example, Patent Document 2). ).

  The air-fuel mixture forming hole and the annular wall portion are provided with air introduction holes for introducing air. In a direct-injection gasoline engine or diesel engine, the fuel injection device may become hot due to heating with combustion gas, and the mixture formation hole and the open space as described above are used for the flow of injected and atomized fuel. It is provided for improvement, suppression of temperature rise of the fuel injection device, and other purposes.

JP-A-6-185433 (paragraph number 0010, FIG. 3 and FIG. 4) Japanese Patent Laying-Open No. 2003-3930 (paragraph number 0065 and FIG. 2)

  A conventional fuel injection device for an internal combustion engine is configured as described above, and the opening space formed by the annular wall portion communicates with the combustion space, but the opening space is closed on the injection port side, Since it is provided in the recessed portion, part of the fuel injected at the end of the injection period stays in the open space without reaching the combustion space. The staying fuel is thermally decomposed by heating with combustion gas or the like. However, since the air necessary for combustion is not sufficiently supplied, incomplete combustion occurs and part of the fuel becomes carbide.

  A part of the carbide generated in the opening space is discharged to the outside of the engine when the combustion space is scavenged, and part of the carbide is pushed out to the combustion space at the next fuel injection, and the rest is opened to the opening space. Stay. The carbide staying in the open space adheres and accumulates on the inner wall of the annular wall portion. In particular, when injection is performed with a plurality of injection holes, the fuel injected from any of the injection holes does not pass between the flow of fuel injected from each injection hole (hereinafter referred to as the gap between the injection fuel flows). And a part of the injected fuel remains. In addition to this, since the influence of the scavenging of the combustion space does not reach, the accumulation on the stagnation portion becomes remarkable.

Accumulated carbides become obstacles to fuel injection, causing changes in the fuel injection amount and the shape of the injected fuel flow, and the combustion characteristics fluctuate greatly due to the effects of accumulated carbides peeling off irregularly. There was a problem such as. In addition, although the air-fuel mixture forming hole and the annular wall portion are provided with an introduction hole for introducing air, it does not function sufficiently to solve such a problem.
The present invention has been made to solve the above-described problems, and is an internal combustion engine that can suppress the accumulation of carbide on a space forming member that is provided on the fuel ejection side of the nozzle and forms an open space. It aims at obtaining a fuel-injection apparatus.

In the fuel injection device for an internal combustion engine according to the present invention, the fuel injection device main body arranged at the tip so that a plurality of injection holes for injecting fuel are on one circumference, and the injection ports of the fuel injection device main body A space forming member that is provided on the fuel injection side and that has an opening on the side opposite to the injection port side to form a cylindrical opening space, and the number of injection holes adjacent to the injection port on the inner periphery of the space formation member And a groove forming part for forming a turning groove in which the circumferential position of the inner peripheral part changes from the same number of nozzle sides toward the opening.

The present invention relates to a fuel injection device main body disposed at a front end so that a plurality of injection holes for fuel injection are on one circumference, and a fuel injection port provided on the fuel injection side of the injection port of the fuel injection device main body A space part forming member having an opening on the opposite side to form a cylindrical opening space, and adjacent to the nozzle holes on the inner peripheral part of the space part forming member from the same number of nozzle holes to the openings. And a groove forming portion that forms a swirling groove whose circumferential position in the inner circumferential portion changes, and thus a flow along the swirling groove is generated, and the flow of gas in the opening space is improved, and stagnation occurs. It can reduce generation | occurrence | production and can suppress the deposit of the carbide | carbonized_material to a space part formation member.

Embodiment 1 FIG.
1 and 2 show a fuel injection device for an internal combustion engine according to a first embodiment for carrying out the present invention. FIG. 1 is a partially sectional perspective view of a main part, and FIG. 2 is a plan view. is there. FIG. 3 is an explanatory diagram for explaining an injected fuel flow in a conventional fuel injection device for an internal combustion engine. 1 and 2, a nozzle hole 2 is provided on the lower surface of the fuel injection device main body 1. In this embodiment, six nozzle holes 2 are arranged at equal intervals on the circle. An open space forming member 3 as a space forming member is fixed to the lower surface of the cylindrical fuel injection device main body 1. The cylindrical opening space forming member 3 has an outer peripheral portion 3a having a constant outer diameter and an inclined inner peripheral portion 3b, and the thickness of the upper upper end portion 3c in FIG. 1 is larger than the thickness of the lower opening portion 3d. It is also thickened. A frustoconical opening space 3e whose diameter gradually increases from the upper end 3c side toward the opening 3d side is formed by the inner peripheral portion 3b of the opening space forming member 3.

The inner peripheral portion 3b is provided with six groove forming portions 3f that form grooves 3g as turning grooves corresponding to the respective nozzle holes 2. The groove 3g starts from a portion where the radiation passing through the nozzle hole 2 from the center of the fuel injection device main body 1 and the inner peripheral portion 3b intersect at the upper end portion 3c, and has a predetermined twist angle (the trajectory of the groove 3g is the outer peripheral portion in the radial direction). This is a groove having a rectangular cross section with the opening 3d as the ending point at a position displaced from the starting point by a predetermined angle toward the lower side in FIG. 1 at an angle formed by a shadow when projected onto 3a. The groove 3g is a turning groove whose position in the circumferential direction of the groove 3g gradually changes from the nozzle side toward the opening when the inner peripheral portion 3b is viewed from the opening 3d side. The opening space forming member 3 is made of, for example, a steel material by a precision casting method.

  Prior to the description of the operation, the flow of injected fuel in the opening space forming member 93 in the conventional fuel injection device for an internal combustion engine will be described with reference to FIG. In FIG. 3, an opening space forming member 93 surrounds the nozzle hole 2 to form a frustoconical opening space 93e having the same shape as the opening space forming member 3 of FIG. In this case, the flow of fuel injected from the nozzle 2 becomes an injected fuel flow j, and a relatively large stagnation k tends to occur between the injected fuel flow j and the injected fuel flow j.

  On the other hand, the fuel injection device for the internal combustion engine in this embodiment operates as follows. In the case of a continuous fluid, the sum of pressure energy, velocity energy, and potential energy is always constant in any part of the fluid. When the difference in potential energy is negligible, the pressure energy around the fuel with high velocity energy injected from the nozzle 2 decreases. That is, the periphery of the injected fuel has a negative pressure, and the effect of attracting the surrounding gas toward the nozzle 2 occurs.

  In the portion where the inner peripheral portion 3b of the opening space forming member 3 and the nozzle hole 2 are close to each other, the surrounding gas is attracted along the inner peripheral portion 3b, but is attracted by the action of the groove 3g provided in the inner peripheral portion 3b. The gas forms a flow along the groove 3g. As described above, when the position of the groove 3g is gradually changed in the circumferential direction toward the opening 3d on the downstream side of the injected fuel, the attracted gas is opened as indicated by an arrow in FIG. It can be made to flow in the circumferential direction of 3e. As a result, the gas can also flow through the portion of the gap between the injected fuel flows where the stagnation portion has been conventionally formed. Accordingly, it is possible to reduce the occurrence of stagnation in the gap between the injected fuel flows of the fuel injected from the nozzle 2 in the opening space 3e, and even if carbides adhere to the inner peripheral portion 3b, they are immediately removed by the swirling flow. Therefore, the accumulation of carbide can be suppressed.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. 4 shows the configuration of the fuel injection device according to the second embodiment of the present invention. FIG. 4 (a) is a partially sectional plan view, and FIG. 4 (b) is an enlarged view of an air inlet formation portion. . In FIG. 4, a notch 13 j is provided in the upper end portion 13 c of the opening space forming member 13, and the air introduction hole forming portion 15 is formed by the notch 13 j and the injection device main body 1. The air introduction hole forming portion 15 forms an air introduction hole 16 in the vicinity of the nozzle hole 2 that connects the opening space 3e and the combustion space outside the opening space forming member 13 in the radial direction of the opening space 3e. Since other configurations are the same as those of the first embodiment shown in FIG. 1, the corresponding components are denoted by the same reference numerals and description thereof is omitted.

  Next, the operation will be described. The operation of providing the groove forming portion 3f on the inner peripheral portion 3b of the opening space forming member 13 and turning the gas attracted by the injection is the same as in the first embodiment. In the second embodiment, since the air introduction hole 16 is provided in the vicinity of the nozzle hole 2 so as to communicate the rear part of the opening space 3e and the combustion space outside the opening space forming member 13, the injection is performed at high speed. The gas in the combustion space flows into the opening space 3e through the air introduction hole 16 due to the pressure difference between the negative pressure generated in the vicinity of the nozzle hole 2 by the action of the fuel and the combustion space.

  As a result, more gas is attracted to the vicinity of the groove 3g, the flow of the injected fuel is further improved, and the occurrence of stagnation in the gap between the injected fuel flows can be reduced. In addition, when the air introduction hole 16 is formed by the air introduction hole forming portion 15 in the vicinity of the injection hole 2 so as to correspond to the injection hole 2 arranged on the outermost periphery in this way, the gas flow resistance from the air introduction hole 16 to the groove 3g. Therefore, a swirl flow can be effectively generated. Therefore, it is possible to more effectively prevent carbide deposition.

  Further, as a modification, as shown in the partial cross-sectional plan view of FIG. 5, the air introduction hole forming section 25 introduces the air in the turning direction of the groove 3 g from the outside of the opening space forming member 3 toward the opening space 3 e. When the hole 26 is formed, the flow of gas from the air introduction hole 26 to the groove 3g becomes smooth, so that the occurrence of stagnation can be further reduced. Therefore, it is possible to more effectively prevent carbide deposition.

  As another modification, as shown in the partial cross-sectional plan view of FIG. 6, the air introduction hole 36 is opened at a position on the radiation different from the nozzle 2 and the groove 3g, for example, between the nozzle 2 and the nozzle 2. Even when the air introduction hole forming portion 35 is configured as described above, it is possible to increase the supply of gas to the vicinity of the injection hole 2 and the groove 3g and improve the flow of injected fuel.

  In each of the above embodiments, the air introduction hole forming portion is configured by the notch provided at the upper end portion of the opening space forming member and the injection device main body. However, the present invention is not limited to this. For example, even if the opening space forming member is provided with a through hole forming portion that forms a through hole that penetrates the opening space forming member in the radial direction, the same effect can be obtained. Further, the opening space forming member is not limited to a member that forms a truncated cone-shaped opening space, and may be a member that forms a linear cylindrical shape or other shape of opening space.

It is a partial cross section perspective view which shows the principal part of the fuel-injection apparatus of the internal combustion engine of Embodiment 1 of this invention. It is a top view which shows the principal part of the fuel-injection apparatus of the internal combustion engine of Embodiment 1 of this invention. It is explanatory drawing for demonstrating the injection fuel flow in the fuel injection apparatus of the conventional internal combustion engine. FIGS. 4A and 4B show a configuration of a fuel injection device for an internal combustion engine according to a second embodiment of the present invention, in which FIG. 4A is a partial cross-sectional plan view, and FIG. 4B is an enlarged view of an air inlet formation portion. FIG. 5 is a partial cross-sectional plan view showing a modification of the fuel injection device for the internal combustion engine shown in FIG. 4. FIG. 10 is a partial cross-sectional plan view showing another modification of the fuel injection device for the internal combustion engine shown in FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection apparatus main body, 2 injection hole, 3 opening space formation member, 3a outer peripheral part,
3b inner peripheral part, 3c upper end part, 3d opening part, 3e opening space, 3f groove forming part,
3g groove, 13, 23, 33 opening space forming member, 15 air introduction hole forming part,
16 Air introduction hole.

Claims (5)

A fuel injection device main body arranged at a tip so that a plurality of injection holes for fuel injection are on one circumference, and the injection ports provided on the fuel injection side of the injection ports of the fuel injection device main body A space forming member having an opening on the opposite side to form a cylindrical opening space, and the same number of nozzle holes as the number of nozzles adjacent to the nozzle holes on the inner periphery of the space forming member A fuel injection device for an internal combustion engine, comprising: a groove forming portion that forms a turning groove in which a circumferential position of the inner peripheral portion changes from the opening toward the opening. 2. The fuel injection device for an internal combustion engine according to claim 1, wherein the space portion forming member forms a cylindrical opening space whose diameter gradually increases from the nozzle side toward the opening. 3. . 2. The internal combustion engine according to claim 1, further comprising an air introduction hole forming portion that is provided in the vicinity of the nozzle and that forms an air introduction hole that communicates the opening space and the outside of the space portion forming member. Fuel injectors. The internal combustion engine according to claim 3, wherein the air introduction hole forming portion is provided corresponding to the nozzle hole and forms an air introduction hole that extends from the outside of the space portion forming member to the vicinity of the nozzle hole. Engine fuel injection device. The air introduction hole forming part is viewed from the opening side of the space part forming member from the outside of the space part forming member in the turning direction of the turning groove toward the opening part from the nozzle side of the space part forming member. 5. The fuel injection device for an internal combustion engine according to claim 4, wherein an air introduction hole is formed toward the vicinity of the injection hole.

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