JP2009114925A - Fuel injection valve - Google Patents

Abstract

An object of the present invention is to remove deposits and suppress adhesion in a fuel injection valve in which an inner crotch portion is formed.
An inflow opening 2a of an injection hole 2 has a rectangular shape, and two injection holes 2 are juxtaposed along the longitudinal direction of the rectangle. An inner crotch portion 6 is formed between the two nozzle holes 2. The nozzle hole 2 has a shape that widens toward the outflow opening 2b from the inflow opening 2a. In the nozzle hole 2 having such a shape, the radius of curvature Rin of the inner side edge 2a1 located in the inner crotch portion 6 is set such that cavitation occurs around the inner side edge 2a1. Further, when comparing the magnitudes of the curvature radius Rin and the curvature radius Rout of the outer edge 2a2 facing the inner edge 2a1, the curvature radius Rin of the inner edge 2a1 is more than the curvature radius Rout of the outer edge 2a2. Is also getting smaller.
[Selection] Figure 4

Description

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

  Various injection hole shapes have been proposed for fuel injection valves used in in-cylinder direct injection engines (hereinafter referred to as “direct injection engines”) in order to meet various needs. A fuel injection valve used in a direct injection engine is attached to a cylinder head with a tip portion exposed in a combustion chamber. For this reason, deposits are easily deposited in the nozzle hole. Deposit accumulation causes blockage of the nozzle hole, resulting in a decrease in fuel flow rate and deformation of the spray shape, and causes problems such as misfire, poor drivability, and poor emission.

  In response to such deposit accumulation, the fuel injection valve used in the direct injection engine has an action of peeling the deposit by the fluid force of the high-pressure injected fuel. At this time, cavitation may occur inside the nozzle hole, and the occurrence of cavitation may effectively act to prevent the separation and adhesion of deposits. The proposal which made the subject the peeling of a deposit using such cavitation as a subject is disclosed by patent document 1, for example.

JP 2005-534844

  As described above, deposits can be peeled off and suppressed in places where strong fluid force can be obtained.However, depending on the arrangement and shape of the nozzle holes, cavitation cannot be used effectively. Deposits may accumulate at these locations. For example, if a so-called inner crotch portion is formed between a plurality of nozzle holes due to a request for a spray shape in a cylinder, the high-pressure fuel flowing from the proximal end side to the distal end side of the fuel injection valve By colliding with the part, the flow velocity of the fuel flowing into the nozzle hole located in the vicinity thereof may be reduced. As a result, deposits cannot be removed, and deposits may accumulate in and around the nozzle holes.

  Therefore, an object of the present invention is to remove deposits and suppress adhesion particularly in a fuel injection valve in which an inner crotch portion is formed.

  According to the present invention for solving this problem, an inner crotch portion formed between a plurality of nozzle holes is provided, and a curvature radius Rin of an inner edge located at the inner crotch portion of the inflow opening of the nozzle hole is set. A fuel injection valve characterized in that cavitation is generated around the inner edge is provided. That is, when the radius of curvature of the edge of the inflow opening increases, the fuel flow in the nozzle hole becomes smooth along the inner wall of the nozzle hole, but when the radius of curvature of the edge of the inflow opening decreases, the fuel injection valve The fuel flowing into the nozzle hole from the continuous fuel flow path from the base end side changes the flow direction sharply, and cavitation is likely to occur. If cavitation occurs, it is possible to receive deposit peeling action and adhesion inhibiting action. In particular, when the inner crotch portion is formed, deposit separation due to the occurrence of cavitation is effective because the fuel collides with the inner crotch portion to reduce the fluid force.

  In such a fuel injection device, the radius of curvature Rin of the inner edge located at the inner crotch portion of the inflow opening of the nozzle hole is made smaller than the radius of curvature Rout of the outer edge facing the inner edge. be able to. Various shapes and arrangements of the nozzle holes are conceivable. For example, a rectangular inflow opening may be provided, and the inflow opening may be arranged in parallel through the inner crotch portion. At this time, it can be set as the structure paralleled along the longitudinal direction of the said rectangle via the said inner crotch part.

  According to the present invention, the radius of curvature of the edge at the inflow opening of the nozzle hole is made small so that the flow direction of the fuel flowing into the nozzle hole is sharply changed to generate cavitation. It is possible to suppress deposit peeling and adhesion in the surroundings.

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

  1 and 2 are a longitudinal sectional view and a lateral sectional view, respectively, of a tip portion where a nozzle hole 2 of a fuel injection valve 1 of the present invention is formed. 1 is a cross-sectional view taken along line BB in FIG. 2, and FIG. 2 is a cross-sectional view taken along line AA in FIG. In the fuel injection valve 1, a sac chamber 4 that is communicated with or cut off from the fuel flow path 3 as the needle valve 5 moves up and down is formed in the nozzle body 10. A nozzle hole 2 is formed. FIG. 3 is an explanatory view showing the periphery of the sack chamber 4 in FIG. 2 in an enlarged manner. Moreover, FIG. 4 is explanatory drawing which expanded and showed the periphery of one nozzle hole 2 in FIG.

  The inflow opening 2a of the nozzle hole 2 has a rectangular shape, and the two nozzle holes 2 are juxtaposed along the longitudinal direction of the rectangle. An inner crotch portion 6 is formed between the two nozzle holes 2. The nozzle hole 2 has a shape that widens toward the outflow opening 2b from the inflow opening 2a. In the nozzle hole 2 having such a shape, the radius of curvature Rin of the inner side edge 2a1 located in the inner crotch portion 6 is set to a size that causes cavitation around the inner side edge 2a1. Further, when comparing the magnitudes of the curvature radius Rin and the curvature radius Rout of the outer edge 2a2 facing the inner edge 2a1, the curvature radius Rin of the inner edge 2a1 is more than the curvature radius Rout of the outer edge 2a2. Is also getting smaller.

  The fuel injection valve 1 having such a configuration is mounted on the cylinder head so that the tip end portion is exposed into the cylinder, and is used as a part of the fuel injection device of the direct injection engine. In the fuel injection valve 1, when the needle valve 5 is raised by a command from an ECU (not shown), the fuel that has passed through the fuel flow path 3 flows into the sac chamber 4, and the fuel in the sac chamber 4 is injected into the cylinder from the injection hole 2. The At this time, at the outer edge 2a2 of the inflow opening 2a, the fuel smoothly flows along the large radius of curvature Rout as indicated by an arrow 7 and flows into the nozzle hole 2 without much lowering the flow velocity, and the outflow opening. It is injected from 2b. On the other hand, at the inner edge 2 a 1 of the inflow opening 2 a, the fuel that has passed through the fuel flow path 3 and the sac chamber 4 flows into the nozzle hole 2 while changing its flow direction sharply as indicated by an arrow 8. In this way, the fuel causes cavitation by changing the direction of flow sharply.

  The generated cavitation acts on deposits formed in and around the fuel injection valve 1, particularly the injection hole 2, and the deposit can be crushed, peeled off and removed. By removing the deposit, it is possible to suppress a decrease in the amount of fuel passing through the nozzle hole 2 to ensure a fuel injection amount according to the injection command and to suppress a change in the spray shape.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited to them. 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. Various shapes can be adopted for the shape and arrangement of the injection holes as required, but the present invention is a fuel injection valve in which a plurality of injection holes are formed and an inner crotch is formed between the injection holes. If applicable, it can be applied. At the inner edge of the inflow opening that is located at the inner crotch and is a continuous portion from the bottom of the sac chamber to the inner wall of the nozzle hole, the radius of curvature is reduced to promote the occurrence of cavitation at that location. Thereby, the deposit can be removed.

It is the BB sectional view taken on the line in FIG. It is the sectional view on the AA line in FIG. It is explanatory drawing which expanded and showed the periphery of the sack chamber in FIG. It is explanatory drawing which expanded and showed the periphery of one nozzle hole in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Injection hole 2a Inflow opening 2a1 Inner side edge 2a2 Outer side edge 3 Fuel flow path 4 Suck chamber 5 Needle valve 6 Inner crotch part 10 Nozzle body

Claims (4)

An inner crotch formed between a plurality of nozzle holes,
A fuel injection valve characterized in that the radius of curvature Rin of the inner edge located at the inner crotch of the inflow opening of the injection hole is sized to generate cavitation around the inner edge. The fuel injection valve according to claim 1, wherein
An inner crotch formed between a plurality of nozzle holes,
The fuel injection valve according to claim 1, wherein a curvature radius Rin of an inner edge located at the inner crotch portion of the inflow opening of the nozzle hole is made smaller than a curvature radius Rout of an outer edge opposed to the inner edge. The fuel injection valve according to claim 1 or 2,
The fuel injection valve according to claim 1, wherein the injection hole includes a rectangular inflow opening, and the inflow opening is arranged in parallel through the inner crotch portion. The fuel injection valve according to claim 1 or 2,
The fuel injection valve according to claim 1, wherein the nozzle hole includes a rectangular inflow opening, and the inflow opening is arranged in parallel along a longitudinal direction of the rectangle through the inner crotch portion.

Images