JP3625834B2 - Fuel injection device with reduced jet diffusion, in particular having a jet off-axis - Google Patents

Description

The invention relates to a fuel injection device of the type for injecting fuel into an internal combustion engine, in particular from a fuel injection device through a thin disk orifice provided in the injector nozzle, in particular in a direction off axis. It relates to a new cooperative form between a needle valve and a valve seat that reduces fuel diffusion. Although the present invention provides significantly reduced diffusion for various multi-split flow shapes, the principles of the present invention can be used with other jet flow shapes.
BACKGROUND AND SUMMARY OF THE INVENTION In order to improve the combustion process in a combustion chamber space of an internal combustion engine so as to meet predetermined objective criteria, in particular criteria relating to exhaust pipe emissions, the fuel is injected from the nozzle of the fuel injector. It has been found that controlling the fuel pattern is an important factor.
The fuel injection device is described in pamphlet of International Publication No. 87/07334. The valve has a valve needle that is attracted towards the core when the magnetic coil is energized. The valve needle is lifted from the valve seat surface formed on the nozzle together with the seal seat portion formed on the valve needle. The seal seat formed on the needle has a round outline, and as a result, the tendency of the needle to adhere to the valve seat provided on the nozzle is reduced.
German Offenlegungsschrift 41 236 92 describes a fuel injection device having a body with an orifice, in which a ball valve is seated, said ball valve having a fuel body. Can be lifted to pass through or dropped to block the fuel passage. The fuel penetrating the main body flows out of the fuel injector valve through a disk having a protruding portion. The protruding portion has a metering orifice through which fuel flows into the engine for combustion.
One aspect of control relates to the degree of diffusion or expansion when the injected fuel flow is discharged from a metering orifice provided in the nozzle, and for a given engine configuration. It is important to limit the diffusivity of the injected fuel stream. The present invention relates to reducing the diffusion of injected fuel, particularly fuel injected off axis from multiple metering orifices. However, certain principles of the present invention can be applied to other orifice configurations.
The present invention does not change the metering orifice, or the thin disc with one or more such metering orifices, but rather the needle valve's tip shape and the corresponding valve seat cooperation with the needle valve. Starting from changing work style. The geometry of the needle tip and the valve seat corresponding to the needle tip can have some effect on the control of the shape of the fuel flow injected from the metering orifice, and at the same time the needle tip relative to the valve seat Has been found to be significantly less diffused than the conventional needle tip with a consistent spherical profile.
According to the present invention, there is provided a fuel injection device for injecting fuel into an internal combustion engine, the fuel injection device including a main body (and a nozzle penetrating the main body and having one or more metering orifices). A fuel passage that communicates with the valve, a fuel is injected from the metering orifice, a valve seat member disposed in the fuel passage inside the main body, and a frustoconical valve A seat and a valve having a composite valve needle surface at the tip are provided, and the valve needle surface is operated with respect to the valve seat to come into contact with and separate from the valve seat. , In the form of closing and opening the flow passage so that fuel can flow to the one or more metering orifices,
For the purpose of directing the fuel flow towards the orifice so that the fuel injected from the fuel injection device forms a compact cone, the valve tip is abutted against the valve seat during operation of the valve. A proximal portion having a spherical surface that touches and separates, and a distal portion having a frustoconical surface extending in a tangential direction from the spherical surface of the proximal portion and ending substantially at the tip of the cone; As a result, the tip portion as a whole forms a substantially complete conical shape.
A more specific aspect relates to the significantly reduced expansion opening obtained for various multi-part flow configurations.
This, as well as other features, advantages and benefits of the present invention, will become apparent from the description of the preferred embodiments with accompanying drawings.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a fuel injection device showing the principle of the present invention.
FIG. 2 is a partial longitudinal sectional view showing the vicinity of the nozzle of the fuel injection device.
FIG. 3 is a view showing a needle tip.
FIGS. 4-10 are graphical diagrams used to show typical improvements obtained by the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a fuel injector 10, which comprises a housing 12 made of a magnetically conductive material, and a fuel inlet pipe 14 also made of a magnetically conductive material, The adjustment tube 16, the helical coil spring 18, the mover 20 to which the needle valve element 21 is coupled, and the solenoid coil assembly 22 are provided, and an electric terminal 23 extends from the solenoid coil assembly 22, and the solenoid In order to selectively energize the coil, a fuel injector is connected to an electrical actuation circuit (not shown) via the electrical terminal 23, and the fuel injector 10 further comprises a non-metallic end cap 24. And a valve body assembly 26.
The relative configuration and arrangement of these various members is substantially the same as that of the fuel injection device shown in US Pat. No. 4,461,0080. This fuel injection device is generally called a top feed type, and in this case, fuel is introduced through a fuel inlet pipe 14 and discharged as an injection from a nozzle end or tip on the opposite side in the axial direction. The principles of the present invention are equally applicable to "side feed" and "bottom feed" fuel injectors.
A fuel inlet tube 14 is disposed within the solenoid coil assembly 22, and the fuel inlet tube 14 carries a pressurized liquid fuel into the fuel injection device, as well as a magnetic circuit that operates the mover 20. Acts as a stator. Together, the lower end portion of the fuel inlet pipe 14 and the upper end portion of the mover 20 define an operating gap 28. Since the axial dimension of the working gap 28 is small, only the line thickness is shown in FIG. When the solenoid coil assembly 22 is not energized, the spring 18 presses the mover 20 in a direction away from the fuel inlet pipe 14, whereby the tip of the needle valve element 21 is moved to the valve seat member 30 (described later). The fuel is prevented from flowing from the inlet to the nozzle through the internal passage of the fuel injector. When the solenoid coil assembly 22 is energized, the solenoid coil assembly 22 attracts the mover 20 toward the fuel inlet pipe 14, thereby lifting the needle valve element 21, so that fuel flows and the engine is discharged from the fuel injector nozzle. (Not shown).
A valve seat member 30 is disposed at the nozzle end of the housing 12, and the valve seat member 30 has a frustoconical valve seat 32. This is shown in more detail in FIGS. In order to guide the movement of the needle in the vicinity of the distal end portion, a needle guide member 36 is fixed to the upstream edge portion of the valve seat member 30, and the needle guide member 36 has a plurality of passages for allowing fuel to pass therethrough. A hole 36a is provided. The valve seat 32 is reduced in hopper shape toward a circular hole 38 closed by a thin orifice disk 40. The backup washer 42 supports the orifice disc 40 with respect to the valve seat member 30, and the backup washer 42, the orifice disc 40, and the valve seat member 30 have an axis line between the inner shoulder 44 and the bent portion 46. By being accommodated in the direction, it is fixed in the axial direction in the nozzle end of the fuel injection device.
The disk 40 has a central recess 48, which has two orifices 48a, 48b diametrically opposed to each other for injecting fuel in two split flow patterns. Each jet tends to diffuse or expand when injected from an orifice. For certain applications where it is particularly important to define the jet aim, it is desirable to minimize jet diffusion. In accordance with the principles of the present invention, this is accomplished by changing the shape of the needle tip so that the needle tip has a proximal portion and a distal portion instead of having a perfectly spherical outline. And in this case the proximal portion has a virtual spherical segment-shaped surface 52 which is geometrically defined by two spaced virtual planes through the virtual sphere. The surface 52 of the proximal end portion is a portion of the distal end portion that contacts and separates from the valve seat 32 when the needle valve element 21 reciprocates. The distal portion has a frustoconical surface 54 that extends tangentially from the surface 52 of the proximal portion. The frustoconical surface 54 advantageously ends in a substantially conical tip 56, so that the entire end portion may be considered to be a substantially perfect cone extending tangentially from the surface 52. The almost perfect cone has a cone with a tip that is slightly blunted or flattened to form a point that is not perfect, but almost sharp.
In the example shown, the surface 52 has a spherical radius of 1.18 mm and the cone angle of the surface 54 is 110 °. The valve seat 32 has an angle of 90 °.
The improvement obtained by such a configuration can be seen by comparing FIGS. 4 to 6 with FIGS. 7 to 10. FIG. FIGS. 4-6 show so-called “topographical plots” of spray diffusion patterns by three substantially identical fuel injectors illustrating the principles of the present invention, whereas FIG. ~ Fig. 10 shows a so-called "topographical map" of the spray diffusion pattern of four fuel injectors having the same needle tip as the above-mentioned three fuel injectors but having a completely spherical outline. It is shown. These tests were performed under the same conditions using a fixed target placed in a plane 143 mm away from the nozzle of the injector. The present invention maintains a spherical contour at the proximal segment of the needle tip for seating, but the frustoconical surface is preferably almost completely conical, starting from this spherical contour segment. have. Since the fuel injection devices tested were substantially the same except for the needle tip, the combination of these surfaces 52, 54 as disclosed in this application allowed the diffusion of fuel injected from each metering orifice. It is clear that it is significantly suppressed.
These orifice disk members formed two split flows that spread in opposite directions rather than parallel to the injector axis 56, but the principles of the present invention to further reduce the spread of individual flows are different. It is applicable to the metering orifice arrangement. Accordingly, the scope of the invention is limited only by the following claims.

Claims (4)

A fuel injection device (10) for injecting fuel into an internal combustion engine comprising a main body (26) and one or more metering orifices (through the main body (26)). 48a, 48b) and a fuel passage that leads to a nozzle, and fuel is injected from the metering orifice, and is further disposed in the fuel passage inside the main body (26). A valve seat member (30), a frustoconical valve seat (32), and a valve (21) having a compound valve needle surface at the tip thereof, the valve needle surface comprising: (32) is operated to abut against or separate from the valve seat (32) to close and open the flow passage, thereby allowing fuel to flow through the one or more metering orifices (48a, 48a, 48b), the type that does not flow or does not flow,
For the purpose of directing the fuel flow towards the orifices (48a, 48b) so that the fuel injected from the fuel injector (10) forms a compact cone, the tip of the valve (21) A base end portion (52) having a spherical surface that contacts and separates from the valve seat (32) when the valve (21) is operated, and extends in a tangential direction from the spherical surface of the base end portion (52) And an end portion (54) with a frustoconical surface ending in a substantially conical tip, so that the tip as a whole forms a substantially perfect cone. A fuel injection device having a jet flow that is less deviated from the axis, especially with reduced jet diffusion. 2. The fuel injection device according to claim 1, wherein the metering orifices (48a, 48b) comprise two orifices diametrically facing each other about the main longitudinal axis of the fuel injection device. The fuel injection device according to claim 2, wherein the orifice (48a, 48b) is disposed in the recess (48). The fuel according to claim 2 or 3, wherein the metering orifice (48a, 48b) and the recess (48) are provided in a separate orifice disc member (40) arranged relative to the valve seat (30). Injection device.

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