JP2008038716A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a VCO (Valve Covered Orifice) type fuel injection valve which uniformly sprays fuel even when nozzle holes are formed in positions of different distances from a seat part. <P>SOLUTION: The fuel injection valve 1 is formed so that a needle valve 20 reciprocating in an axis NA direction is disposed in a nozzle body 10 formed with the plurality of nozzle holes 11a, 11d in a tip and closes the nozzle holes when the seat part 21 of the needle valve 20 is seated in the nozzle body. The plurality of nozzle holes include those disposed at the positions different in distance from the seat part. An inner wall 13B of the nozzle body is formed with elongate grooves 12a, 12d disposed symmetrically about the axis and the nozzle holes 11a, 11d are formed in the elongate grooves 12a, 12d. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection valve that can be suitably used in an internal combustion engine such as a diesel engine. More specifically, the present invention relates to a so-called VCO (Valve Covered Orifice) type fuel injection valve.

  In an internal combustion engine such as a diesel engine, a fuel injection valve that injects fuel into a cylinder is employed. A general fuel injection valve includes a nozzle body provided with an injection hole and a needle valve arranged so as to be movable in the central axis direction within the nozzle body. And by moving a needle valve, the opening degree of a nozzle hole is adjusted and fuel is injected. Such a fuel injection valve is preferably one that can inject fuel with a uniform spray shape and spray amount. In this way, the spray state is made uniform to improve internal combustion engine emissions and fuel consumption. Can do.

  Conventionally, a VCO (Valve Covered Orifice) type fuel injection valve configured to close a nozzle hole with a part of a conical shape formed at the tip when a needle valve disposed inside is lowered to a lower limit position. (Hereinafter referred to as VCO type fuel injection valve) is known. A VCO type fuel injection valve is disclosed in Patent Document 1, for example. The VCO type fuel injection valve is formed so that the seat portion of the needle valve (needle valve) is seated at a fixed position on the inner wall of the nozzle body (valve body). Then, the valve valve closed state is formed by closing the nozzle hole of the nozzle body with the inclined surface of the needle valve formed on the tip side of the seat portion when seated. When the needle valve is lifted up, it is separated and opened, and fuel is injected from the injection hole.

Japanese Patent Laid-Open No. 5-231261

  By the way, the attitude of the fuel injection valve inserted into the cylinder (combustion chamber) of the diesel engine varies depending on the engine design. That is, the fuel injection valve may have a posture inserted straight in parallel to the reference axis (cylinder central axis) on the combustion chamber side, or may have a posture inserted obliquely. On the other hand, it is required to perform similar fuel spray in the cylinder regardless of the attitude of the fuel injection valve. Therefore, when the fuel injection valve is inserted obliquely, the position and orientation of the injection hole are appropriately adjusted so that the same fuel spray as that obtained when the fuel injection valve is inserted straight is obtained. . This point will be described with reference to the drawings.

  3A and 3B are views showing the VCO type fuel injection valve 100 used in an oblique posture. FIG. 3A is an enlarged view of the periphery of the tip portion of the fuel injection valve 100, and FIG. It is the figure which showed the mode of the nozzle hole arrangement which is the AA arrow figure in).

  The fuel injection valve 100 includes a nozzle body 110 and a needle valve 120 disposed therein. The fuel injection valve 100 is arranged with a central axis NA inclined with respect to a reference axis EA inside the engine cylinder (not shown). When the fuel injection valve is tilted in this way, as shown in the figure, the positions and angles of the plurality of injection holes 111 formed in the nozzle body 100 are set so that the spray into the cylinder is uniform. It is necessary to adjust appropriately. In the case of a fuel injection valve that is inserted straight, the engine-side reference axis EA and the center axis NA coincide. Therefore, the nozzle holes may be formed radially around the central axis NA. A straight type fuel injection valve is easier to manufacture. However, if this straight type fuel injection valve is inserted obliquely and used, spraying in the cylinder becomes non-uniform. Therefore, as shown in FIG. 3, the position and angle of the nozzle hole 111 are appropriately adjusted so that the spray in the cylinder is uniform.

  However, when the VCO type fuel injection valve is used in an oblique posture, the following inconvenience may occur. Since the positions of the plurality of nozzle holes are appropriately adjusted, the distance from the seat portion 121 of the needle valve 120 differs depending on the nozzle holes. (B) schematically shows the position of each nozzle hole from the inside of the nozzle body 110. The nozzle hole 111a has a short distance from the sheet part 121, and the opposite nozzle hole 111d has a distance from the sheet part 121. Is long. The distances from the seat portion 121 are also different for the nozzle holes 111b and 111c located in the middle thereof.

  When the seat part 121 is seated on the nozzle body 110, the fuel flow is prevented from flowing in from the upstream side, and the valve holes are closed by the inclined surfaces of the needle valve 120, thereby forming a closed valve state. And when the seat part 121 leaves | separates, it opens. Therefore, if the nozzle holes are formed at different positions from the seat portion 121, the inflow conditions (flow rate and pressure) of the fuel flowing into each nozzle hole are different, so the fuel spray state from each nozzle hole is not good. It will be uniform. That is, in order to make the fuel injection into the cylinder uniform, the position and orientation of the injection hole are changed as shown in FIG. 3, but if the distance from the seat portion differs depending on the injection hole, the fuel inflow condition May change and the spray state may become non-uniform. An internal combustion engine that employs such a fuel injection valve is concerned about the deterioration of emissions and fuel consumption.

  Accordingly, an object of the present invention is to provide a VCO type fuel injection valve capable of spraying fuel uniformly even when injection holes are formed at positions where the distance from the seat portion is different.

  The object is to arrange a needle valve that reciprocates in the axial direction in a nozzle body having a plurality of nozzle holes formed at the tip, and when the seat portion of the needle valve is seated in the nozzle body, A fuel injection valve formed so as to close an injection hole, wherein the plurality of injection holes are arranged at different distances from the seat portion, and the inner wall of the nozzle body Is provided with a long groove arranged symmetrically with respect to the axis, and the injection hole is formed in the long groove.

  According to the present invention, since the long groove is formed at the same position from the seat portion, the fuel can be caused to flow in the same manner. Each nozzle hole is formed in the long groove. Therefore, the fuel can be uniformly sprayed under the same conditions for the fuel flow into each nozzle hole. An internal combustion engine that employs such a fuel injection valve can improve emissions and fuel consumption.

  In addition, it is desirable that the long groove adopt a structure formed in parallel with the axis and in the same shape. Since such a structure can be easily formed in the nozzle body, the manufacturing cost can be suppressed.

  According to the present invention, it is possible to provide a VCO type fuel injection valve capable of spraying fuel evenly even when the injection holes are formed at different positions from the seat portion.

  Hereinafter, a VCO type fuel injection valve (hereinafter simply referred to as a fuel injection valve) according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged view of the periphery of the tip portion of the fuel injection valve according to the embodiment.

  The fuel injection valve 1 includes a cylindrical nozzle body 10 having a space inside, and a needle valve 20 housed in the nozzle body 10 and arranged to reciprocate in the direction of the central axis NA. It is out. The central axis NA of the fuel injection valve 1 is inclined with respect to the reference axis EA inside the engine cylinder.

  The inner wall 13 of the nozzle body 10 has a cylindrical inner wall 13A on the upper side and a conical inner wall 13B on the lower side. When the needle valve 20 is lowered, the seat portion 21 is seated on a part of the inner wall 13B. This position is the lower limit position of the needle valve 20, and the fuel injection valve 1 is thereby closed.

  A plurality of nozzle holes 11 are formed at the tip of the nozzle body 10. In the plurality of nozzle holes 11, as in the case of the conventional nozzle body, a nozzle valve 20 is located at a position where the distance from the seat portion 21 is different. Therefore, also in the case of the fuel injection valve 1 of the present embodiment, injection holes are formed at positions where the fuel inflow conditions are different, as in the conventional case described above. However, in this embodiment, the inner wall 13B of the nozzle body 10 in which the nozzle holes 11 are formed is formed in a new shape different from the conventional one. Hereinafter, this point will be described.

  2 is a view taken along the line B-B in FIG. 1, and is a diagram schematically illustrating the state of the nozzle hole arrangement. The structure around the nozzle hole 11 will be described with reference to FIG.

  A plurality of long grooves 12 are formed in the inner wall 13 </ b> B of the nozzle body 10. The long groove 12 is formed according to the number of nozzle holes. That is, in this embodiment, as shown in FIG. 2, a case where six nozzle holes 11a to 11f are formed is illustrated, and six long grooves 12a to 12f are formed accordingly. In FIG. 2, the nozzle hole 11b and the nozzle hole 11f, and the nozzle hole 11c and the nozzle hole 11e are in a line-symmetrical positional relationship (symmetric to a line connecting the nozzle hole a and the nozzle hole d).

  The six long grooves 12 are formed on the inner wall 13 </ b> B with point symmetry about the central axis NA of the fuel injection valve 1. More specifically, each long groove 12 is a recess formed under the same conditions around the axis with the central axis NA as the center. That is, each long groove 12 is formed in substantially the same height position and shape in the direction of the central axis NA. And the nozzle holes 11a-11f are each formed in each long groove 12a-12f.

  The injection hole 11 is set at a position where the distance from the seat portion 21 of the needle valve 20 is different because the fuel injection valve 1 is disposed in an oblique posture. For this reason, since the inflow conditions of the fuel flowing into each nozzle hole 11 become unstable, the spray state may vary.

  In contrast, in the fuel injection valve 1 of the present embodiment, the long grooves 12a to 12f are formed in the inner wall 13B of the nozzle body 10. Although the distance from the sheet part 21 to the nozzle holes 11a to 11f is different, the positional relationship between the long grooves 12a to 12f and the sheet part 21 is the same. Therefore, when the needle valve 20 is separated from the valve-closed state, the fuel flows into the long grooves 12a to 12f under substantially the same conditions to fill the inside. And when each long groove 12a-12f will be in the state with which it filled with fuel, fuel will be injected from each nozzle hole 11a-11f. Thus, a long groove having a constant volume is provided, fuel is temporarily stored in the long groove, and fuel is injected from the long groove, so that the spray shape and the injection amount can be made uniform.

  That is, in the structure of the present embodiment, the long grooves 12 corresponding to the number of the nozzle holes 11 are formed on the inner wall 13B of the nozzle body 10 in a point-symmetric manner around the central axis NA. The long grooves 12 a to 12 f are formed at the same position from the seat portion 21 of the needle valve 20. Therefore, fuel can flow into each long groove under the same conditions. The nozzle holes 11a to 11f are formed in the long grooves 12a to 12f. The inflow conditions of the fuel to each nozzle hole 11a-11f can be made the same. Therefore, the spray state from each nozzle hole 11a-11f can be made uniform.

  An internal combustion engine such as a diesel engine to which the fuel injection valve according to the embodiment described above is applied can improve fuel consumption and emissions.

  In the above embodiment, the case where the long groove 12 is arranged in parallel with the central axis NA of the fuel injection valve 1 has been described. That is, as shown in FIG. 2, the case where the direction in which each long groove 12 extends is parallel to the central axis NA has been described. Such a structure can be manufactured without increasing the manufacturing cost because it merely forms a long groove (long recess) along the central axis NA in the inner wall 13B. However, the long groove of the present invention is not limited to such a form. As illustrated for the long groove 12f in FIG. 2, the direction SA in which the long groove extends may be inclined by a predetermined angle α with respect to the central axis NA.

  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 the longitudinal cross-sectional view shown about the fuel injection valve which concerns on an Example. FIG. 2 is a diagram showing the structure of the nozzle body of the embodiment described in FIG. 1 on the right side and the structure of a conventional general nozzle body as a comparative example on the left side. It is the figure which showed typically the conventional processing method of the fuel injection valve using an abrasive fluid.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 10 Nozzle body 11 (11a-11f) Injection hole 12 (12a-12f) Long groove 13 (13A, 13B) Inner wall 20 Needle valve 21 Seat part FE Fuel NA Center axis EA Engine side axis

Claims (2)

A needle valve that reciprocates in the axial direction is disposed in a nozzle body having a plurality of nozzle holes formed at the tip, and the nozzle hole is closed when a seat portion of the needle valve is seated in the nozzle body. A fuel injection valve formed as follows:
The plurality of nozzle holes that are formed include ones that are arranged at different positions from the sheet portion,
The inner wall of the nozzle body is provided with long grooves arranged symmetrically around the axis,
The fuel injection valve, wherein the injection hole is formed in the long groove. 2. The fuel injection valve according to claim 1, wherein the long grooves are formed in the same shape parallel to the shaft.

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