JPS62214265A - Multi-nozzle hole nozzle for injecting fuel for diesel engine - Google Patents

Abstract

PURPOSE:To prevent mist from adhesion to the side peripheral wall of a combustion chamber and to prevent production of blue while smoke, by a method wherein nozzle holes are formed in plural spots in the peripheral direction of the suck part of a multi-nozzle hole nozzle, and a spray angle enlarging groove is formed in a particular state. CONSTITUTION:Nozzle holes 3 are formed in plural spots in the peripheral direction of a suck part 2 of a multi-nozzle hole nozzle 1 for injecting fuel of a diesel engine E. A spray angle enlarging groove 6, enlarging the direction of the spray angle of fuel, is formed in an outer peripheral surface 7 of the suck part 2 in a state in that it is extended across an outlet 4 of the nozzle port 3. Since the bore of a combustion chamber 5 can be increased, fuel sprayed through the nozzle 1 is drawn in a swirl throughout a long distance until it approaches the side peripheral wall of the combustion chamber 5, and is diluted. This constitution enables prevention of adhesion of mist to the side peripheral wall of the combustion chamber, and prevention of the production of blue white smoke.

Description

[Detailed Description of the Invention] <Field of Industrial Application> The present invention relates to a multi-hole nozzle for fuel injection suitable for use mainly in small-displacement diesel engines, which eliminates the generation of blue-white smoke during startup. However, to provide an apparatus that improves the efficiency of empty space utilization in mixing and stirring fuel using a stool during busy periods of operation, and allows the spray angle to be adjusted with high precision through simple machining.

Prior art> In conventional multi-nozzle hole nozzles, the nozzle is simply a fine hole with a circular cross section and a diameter of 1 mm or less in the sack part, and the atomized fuel ejected from this hole has a circular cross section. It had become.

<Problems to be Solved by the Invention> In a small displacement direct injection diesel engine with a stroke volume of, for example, 1000 cc or less, the volume of the dish-shaped or toroidal cavity-shaped combustion chamber recessed in the piston head must be sufficiently large. If the fuel injection conditions are not good,
There is a problem in that blue and white smoke is likely to be generated when starting.

That is, as is well known, volumetric efficiency and swirl flow velocity are determined by the shape of the intake boat, etc., and it is difficult to achieve both.

Therefore, in order to obtain high output during operation, it is necessary to ensure high volumetric efficiency, and in this case, the flow velocity of the swirl cannot be made sufficiently high.

Therefore, in order to sufficiently diffuse the fuel sprayed into the combustion chamber from the nozzle with this low-velocity swirl and increase the air utilization rate, it is necessary to reduce the diameter of the combustion chamber and increase the angular velocity.

This small-diameter combustion chamber is superior in that it can obtain high output because it ensures high volumetric efficiency during operation, and that combustion efficiency increases because the air utilization rate is high even with the low-speed swirl mentioned above. .

Note that a large amount of the injected fuel collides with the peripheral wall of the small-diameter combustion chamber and attempts to adhere to it, but since the peripheral wall of the combustion chamber is heated to a high temperature by the heat of combustion, the fuel that collides with and adheres to the surrounding wall of the combustion chamber is heated to a high temperature. Since it is quickly heated and vaporized, combustion performance does not deteriorate.

However, when the engine is started, the peripheral wall of the combustion chamber has not yet been heated to a high temperature, so the large amount of fuel that collides with the fuel cannot be heated and vaporized, and the fuel continues to accumulate, resulting in poor combustion. However, there is a problem in that it generates blue-white smoke.

For this reason, it is conceivable that the diameter of the combustion chamber may be made larger to increase the scattering distance of the mist sprayed from the nozzle, thereby diluting the mist before it adheres to the side peripheral wall of the combustion chamber, but in this case If the spray angle from the nozzle is the same as before, since the shape of the intake port is constant, the circumferential velocity of the swirl is also constant and cannot be increased, so the fuel injected from one nozzle is spread in the circumferential direction of the stool. A gap U is created between the range P where fuel can be mixed and stirred and the range Q where fuel is mixed and stirred sprayed from the nozzle of the pond adjacent in the swirl direction (see Figure 3), so that a part of the swirl is mixed with the fuel. Otherwise, the air utilization rate will decrease.

On the other hand, as mentioned above, the volume of the combustion chamber is fixedly determined by the compression ratio of the engine, so if the diameter of the combustion chamber is made large, its depth must be made shallow in inverse proportion to this.

Therefore, by appropriately widening the spray angle from the nozzle to increase the spread of fuel in the circumferential direction of the combustion chamber, it is possible to increase the air utilization rate. Fuel adheres to the end face facing the combustion chamber, reducing combustion efficiency and causing blue-white smoke.

The technical object of the present invention is to prevent the generation of blue-white smoke at the time of startup, and to improve the air utilization efficiency in mixing and stirring fuel and swirl.

Means for Solving the Problems> Means for achieving the above problems will be described below with reference to FIGS. 1 to 11, which correspond to embodiments.

That is, the present invention provides injection ports 3 at a plurality of locations in the circumferential direction of the sack portion 2 of a multi-injection hole/zuru 1 for fuel injection of a diesel engine E, and at least one injection port 3 among the plurality of injection ports 3. At the outlet 4 of the nozzle 3, a spray angle enlarging groove makes the spray angle β along the circumferential direction T larger than the spray angle a along the axial direction S of the combustion chamber 5 when fuel is sprayed from the nozzle 3. 6 is formed on the outer circumferential surface 7 of the sack portion 2 so as to cross the outlet 4 of the spout 3.

Effect> The spread of the spray from nozzle 1, that is, the spray angle is
determined by the length and diameter of the
Moreover, the spray angle becomes larger as the diameter becomes smaller.

Therefore, if a spray angle expanding groove 6 is formed across the outlet 4 of the nozzle 3, the cut corner of the nozzle outlet 4 in a plane orthogonal to the transverse direction will have a shape in which the center of the groove extends inward. Since the length of the nozzle path in the transverse plane including this central portion is the shortest, the fuel spray emitted from the nozzle spreads in the above-mentioned transverse direction, that is, in the circumferential direction T of the combustion chamber 5.

On the other hand, since the path length at the upper and lower edges of the cut remains the same as before the groove was formed, the length of the nozzle path in the longitudinal section perpendicular to the above-mentioned transverse direction is the original length of the nozzle. is equal to the length of the nozzle path in the transverse plane, and is longer than the length of the nozzle path in the transverse plane, and is
The spray angle a toward the combustion chamber 5 is smaller than the angle β toward the circumferential direction T of the combustion chamber 5.

Therefore, the cross section of the atomized fuel in the direction perpendicular to the injection direction expands into an elliptical shape, a rhombus shape, a rectangular shape, or any horizontally elongated shape having a horizontal long axis as shown in FIG.

Therefore, a description will be given of the state of fuel spray when the diameter of the combustion chamber 5 is increased, the bottom wall thereof is set shallow, and fuel is injected into the combustion chamber 5 from the nozzle 1.

First, when looking at the fuel spray state in plan, the spray angle β increases, and the fuel sprayed from one outlet 4 is mixed and stirred in the direction R of the school, and the fuel sprayed from other nozzles adjacent to the stool direction is mixed and stirred. The fuel injection region K is reached (see FIG. 3).

As a result, even in the case of a swirl that must be kept at a low velocity in order to ensure high volumetric efficiency, the sprayed fuel is sufficiently diffused over almost the entire opening angle of the narrow fuel dome.

On the other hand, when the fuel spray state is viewed from the side, the spray angle a is small, so even if the combustion chamber is shallow, the fuel does not adhere to the bottom wall of the combustion chamber, and the same applies to the end surface of the cylinder head.

<Effects of the Invention> Since the diameter of the combustion chamber can be increased, the fuel sprayed from the nozzle is drawn into the tool over a long distance before it approaches the side wall of the combustion chamber, becoming diluted, and the mist is spread onto this side wall. Eliminates adhesion. In addition, even if the diameter of the combustion chamber is increased and the bottom wall is made shallower, the spray angle along the axis of the combustion chamber is small, so mist may adhere to the shallow bottom wall or the end face of the cylinder head. Therefore, the generation of blue-white smoke at the time of starting can be smoothly prevented as a whole.

On the other hand, since the spray angle along the circumferential direction of the combustion chamber is large, the sprayed fuel and swirl can be mixed and stirred efficiently, improving the air utilization rate of the stool and increasing the combustion efficiency during operation.

It is possible to form a spray angle enlarging groove at the outlet of the nozzle by a simple process such as cutting the outlet of the nozzle into a transverse shape, and furthermore, it is possible to change the shape of this enlarged groove. The spread angle of the spray can be adjusted with high precision.

In addition, in the case of a high-speed engine, it is sufficient to form the spray angle enlargement groove shallowly and set the spray angle small; on the other hand, in the case of a low-speed engine, it is sufficient to form the spray angle enlargement groove deeply and set the spray angle small. Although the angle must be increased, this can be achieved by changing the depth of the spray angle expansion groove for both engines of this type, so if a multi-nozzle hole nozzle with an expansion groove of a predetermined depth is installed, high speeds can be achieved. The cylinder head and piston can be made into common parts for both low-speed and low-speed engines.

<Example> Embodiments of the present invention will be described below based on the drawings.

The mi diagram is a longitudinal sectional front view of the main part of the direct injection diesel engine around the cylinder, Fig. 2 is a partial longitudinal sectional front view of the sack part of the multi-nozzle hole nozzle, and Fig. 3 is a schematic plan view of the combustion chamber. In the center of the cylinder block 8 of the engine E, a cylinder 1o is fitted into a cylinder 10 of mL, t, and t positions so that a piston 119L-τ can be freely rotated.

A cylinder head 12 is assembled above the cylinder block 8, and a nozzle fitting hole 13 is formed in the center thereof.

A Troigle type swirl promoting hole 5 is formed at the center of the upper end of the piston 11 (that is, this promoting hole 5 becomes a combustion chamber), and the portion of the lower end surface 14 of the cylinder seat 12 facing the swirl promoting hole 5 Install a combustion section 45 in the combustor.

Then, the multi-nozzle hole nozzle 1 is inserted into the nozzle insertion hole 13.
is inserted so that the sack portion 2 at the tip thereof protrudes into the combustion recess 45 and faces the swirl promotion hole 5.

Four nozzles 3 are installed in the sack part 2 of the multi-nozzle hole nozzle 1.
Space them out at equal distances from each other, sloping downward toward the tip.

An arc-shaped circumferential groove 16 is continuously formed on the outer circumferential surface 7 of the sack part 2 in a state that crosses the outlet 4 of the nozzle 3, and all four nozzle outlets 4 have the same radius of curvature. Providing the angle enlargement groove 6 - The volume of the swirl promoting hole 5 is set to correspond to a predetermined compression ratio of the engine, and the diameter of the promoting hole 5 is made large and the depth is made shallow.

In this case, the suck part 2 of the nozzle is the hole 5 for promoting swirl.
The fuel injected from the nozzle 3 spreads in the circumferential direction T of the swirl promotion hole 5 (that is, the spray angle β is large as shown in FIG. 3), but the fuel injected from the nozzle 3 spreads in the circumferential direction T of the swirl promotion hole 5
The spray does not spread much in the narrow direction S (that is, the spray angle a is small, as shown in FIG. 2).

The cut end of the nozzle outlet 4 in the plane orthogonal to the direction that the enlarged groove 6 crosses may have a shape in which the central part of the nozzle outlet 4 is inward, so the spray angle enlarged groove 6 has the shape of a circle shown in FIG. It is not limited to an arc shape, but may be formed into a linear mountain shape as shown in Figure 5 or a curved mountain shape as shown in Figure 6.

Further, as shown in FIG. 7, the vertical width of the spray angle expanding groove 6 may be made narrower than the diameter of the nozzle 3, or as shown in FIG. 8, the vertical width of the expanding groove 6 may be widened. do not have.

In order to avoid the intake/exhaust ports, the fuel injection nozzle 1 is sometimes arranged to face the swirl promoting hole 5 obliquely and eccentrically from the center of the swirl promoting hole 5 as shown in Figure 1nl1.

Even in this case, the width 18 of the fuel spray spreading from each nozzle 3 to the side peripheral wall 17 of the promoting hole 5 must be the same, so for example, in the case of a 4-hole nozzle, the spray angle β from each nozzle 3 is It is necessary to change β1, β2, etc., but according to the present invention, as shown in FIG. The desired conditions can be easily met by making the spray angle smaller, forming enlarged grooves 6 in other nozzles 3, and appropriately increasing the spray angle compared to the nozzles 3 without the enlarged grooves. .

Moreover, as shown in FIG. 10, by forming arc-shaped enlarged grooves 6 in all four nozzles 3 and changing the radius of curvature of each enlarged groove 6, the spray angle can be freely changed. For example, if an enlarged groove 6 with a large radius of curvature (that is, a shallow arc shape) is formed, the spray angle β can be reduced, and conversely,
By forming the enlarged groove 6 with a small radius of curvature (that is, deep arc shape), the spray angle β can be increased.

The enlarged grooves 6 may be formed continuously in the circumferential direction of the sack portion 2, but may also be formed intermittently for each nozzle port 3 as shown in Fig. m12.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of the main part of a direct injection diesel engine around Schilling, FIG. 2 is a partial longitudinal sectional front view of the sack part of a multi-hole nozzle, and The figure is a schematic plan view of the combustion chamber, Figure 1@4 is a vertical cross-sectional view of the spray, Figures 5 to 10 are enlarged vertical cross-sectional views of the main parts around the nozzle showing an embodiment of the pond of the present invention, and Figure 11 is a schematic plan view of the combustion chamber. This figure is a view corresponding to FIG. 3 showing a combustion chamber with an eccentric nozzle, and FIG. 12 is a cross-sectional plan view of the sack portion of the nozzle showing the case where enlarged grooves are formed intermittently at each nozzle. DESCRIPTION OF SYMBOLS 1...Multi-nozzle hole nozzle, 2...Sack portion of 1, 3...Nozzle port, 4...Outlet of 3, 5...Combustion chamber, 6...Spray angle expansion groove, 7. ...outer peripheral surface of 2, E...diesel engine, S...axial direction of 5, T...circumferential direction of 5, a...spray angle along S, β...along T spray angle. Patent applicant Kubota Iron Works Co., Ltd. Kan110 Kan91!1 Sat

Claims (1)

[Claims] 1. Nozzles 3 are provided at a plurality of locations in the circumferential direction of the sack portion 2 of a multi-nozzle hole nozzle 1 for fuel injection of a diesel engine E, and at the outlet 4 of at least one of the multiple nozzles 3, Spray angle α along the axial direction S of the combustion chamber 5 when fuel is sprayed from the nozzle 3
A spray angle enlarging groove 6 that increases the direction of the spray angle β along the circumferential direction T is formed on the outer circumferential surface 7 of the sack portion 2 at the nozzle 3.
A multi-hole nozzle for fuel injection of a diesel engine, characterized in that the hole nozzle is formed to cross an outlet 4 of a diesel engine.