JPS58143162A - Fuel injection nozzle for diezel engine - Google Patents

Abstract

PURPOSE:To improve combustion efficiency by forming the section of a nozzle provided on an end of a valve body into the V-shaped one. CONSTITUTION:The section of a nozzle 70 provided on a nozzle section 30 is formed of a Y-shaped slit, two sides a, b of which are directed to the cylinder head side and the another side c of which is directed to the piston combustion chamber 4 side. Thus, fuel spray a', b' from the two sides a, b collide with the inside from the outlet of the piston combustion chamber 4 and the fuel spray c' from the another side c is distributed toward the bottom of the combustion chamber 4 so that the introduction of air from the connections of three sides a-c is promoted to improve the mixing of air and atomized fuel and combustion efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a fuel injection nozzle that is installed in a diesel engine or the like and injects fuel into a combustion chamber.

FIG. 1 is a partially cutaway side view showing the structure of a fuel injection nozzle 1 installed in a conventional diesel engine.
A cylinder head 2 of a diesel engine, indicated by a dotted chain line, is fitted with a tip end 3 (1) facing a combustion chamber 4, and is configured to inject injected fuel f into the combustion chamber 4.

However, in this type of fuel injection nozzle 1, the valve body 6 into which the needle valve 5 is slidably fitted is integrally made of heat-resistant steel up to the tip 3 where the nozzle hole 7 is formed.

Therefore, the tip 3 of the injection nozzle of the injection hole 7 receives radiant heat directly from the combustion chamber 4, and due to the heat, the needle valve 5
The occurrence of problems such as seizure of the valve, clogging of the nozzle hole 7, and excessive wear of the valve seat 8 had to be avoided.

In addition, since the injection hole 7 is also formed at the tip 3 of the injection nozzle made of heat-resistant steel, its cross-sectional shape 7 is
In most cases, s was circular.

Therefore, the fuel spray f injected into the combustion chamber 4 from the nozzle hole 7 is dense at the center and thin at the outer periphery, making it impossible to achieve homogeneous mixing with the air flow inside the combustion chamber 4, resulting in a clearer surface. 2) There was a drawback that proper combustion was not obtained.

The present invention was obtained in order to eliminate the drawbacks of the conventional fuel injection nozzle, and also fully utilizes the moldability and precision of ceramic,
At least the nozzle hole located at the tip of the valve body is made of ceramic material, and the shape of the nozzle hole is formed into a figure 7 shape, with two sides of the slit in the figure 7 facing the cylinder head side. The first feature is that the other side is arranged above the flat surface of the opening of the piston combustion chamber.

The second feature is that there is a dimensional relationship between the width and length of the side of the nozzle hole in order to efficiently diffuse the injected fuel.

The present invention will be described in detail below with reference to the drawings.

FIG. 3 is a partially cutaway sectional view showing an embodiment of the fuel injection nozzle according to the present invention, FIG. 4 is an enlarged sectional view of the tip of the fuel injection nozzle in the same embodiment, and FIG. FIG. 3 is an enlarged front view of a nozzle hole provided at the tip.

In the present invention, the injection hole portion 30 at the tip of the valve body 6 of the fuel injection nozzle 10 is made of a ceramic material, and
After inserting the key 11 into the key groove 61 formed on the outer periphery to position the valve body 6 and the nozzle hole 30, fit the nozzle nut 9 from below the nozzle hole 30, and screw the nozzle nut 9 into place. The part 9a is fitted onto the threaded part 6a of the valve body 6, and the nozzle hole part 30 is attached to the cylinder head 2 of a diesel engine (FIG. 3), which is indicated by a two-dot chain line, so that the nozzle hole part 30 faces the combustion chamber 4.

The ceramic material constituting the nozzle hole portion 30 may be a silicon nitride (SisN4) sintered body having the physical properties listed in Table 1 or a sialon made of silicon nitride containing an aluminum oxide (^1,0.) component. Sintered bodies are the most suitable ceramic material.

As is clear from Table 1, silicon nitride sintered bodies have properties that are much superior to metal materials and conventional alumina ceramics in terms of high-temperature strength, and they also have extremely high resistance to thermal shock (3). In addition, it has a low thermal expansion coefficient and low thermal conductivity, making it ideal for the nozzle configuration of the injection hole portion 30 of the fuel injection nozzle.

An important point in the present invention is that at least the nozzle hole portion 30 of the fuel injection nozzle 10 is made of ceramic, and the shape of the nozzle hole 70 is formed into a 7-shape by taking advantage of the characteristics of this ceramic material.

The nozzle hole 70 is shown in an enlarged view in FIG. Side C is formed toward the top of the piston.

The ratio between @S and the length of the sides a, b, and c is preferably determined as follows.

S-L/2~L15 By making the nozzle hole 70 into a 7-shaped shape as described above, the fifth
Spray $18'% due to upper sides a and b as shown in the figure
b'' is located inward from the piston combustion chamber outlet, and the jet 11c' on one side C of the lower part of the nozzle hole is distributed along the combustion chamber wall.

(5) (4) Figures 6A and 6B compare the state of fuel spray between the figure 7-shaped hole of the present invention and a normal round hole, and show that the fuel injection nozzle according to the present invention In this case, the surface area of the outer periphery of the fuel spray S increases, and the air introduction rate shown by the arrow in an arbitrary cross section perpendicular to the traveling direction of the spray S becomes 6th.
It can be seen that the nozzle size has increased significantly compared to the conventional round nozzle shown in Figure B. Incidentally, for the spray S injected from nozzle holes with the same cross-sectional area, the contact area of air in any cross section between the spray S from the figure-7-shaped nozzle hole and the one from the round-shaped nozzle hole is It is 1.5 to 5 times larger than the round shape.

FIG. 7 is a diagram showing the relationship between fuel equivalence ratio, smoke, and output. Curve Y shows data for the nozzle of the present invention, and curve R shows data for a conventional nozzle.

According to FIG. 7, it can be seen that the average effective pressure Pme of the straight line Y representing the data of the nozzle of the present invention increases and the smoke decreases compared to the curve R representing the data of the conventional nozzle.

(6) Furthermore, the effect of this improvement is remarkable in the shaded area between the two curves, where the fuel equivalent is large.

On the other hand, the tip of the nozzle, especially the nozzle hole 3o, is in direct contact with the flame, so it remains at a very high temperature, and as the temperature increases, scratches and the like occur. Therefore, it is preferable to improve the surface precision of the contact area 32 between the nozzle hole 30 and the main body 6 so that heat transfer is good, or to insert a material with good heat transfer, such as copper, into this contact area 32. .

In the present invention, as described above, the nozzle hole portion 30 of the fuel injection nozzle is made of ceramic, and the jet 70 provided in this nozzle hole portion has a 7-shaped cross section. It is distinctive in that the remaining side faces the piston combustion chamber.

Therefore, as shown in FIG. 5, the upper two sides a of the nozzle hole 7o,
The sprays a' and b'' caused by b collide inside the outlet of the piston combustion chamber 4, and move toward the bottom of the combustion chamber on one side C of the lower part.
Since the spray C° is distributed, the spray is distributed in a figure 7 shape, spreading in three directions, so it is possible to promote the introduction of air from the (7) joints on these three sides, as shown in Figure 6. This makes it possible to improve the mixing state of air and atomized fuel, thereby improving combustion efficiency.

In order to further increase the above effects, it is preferable to set the ratio of the width S to the length of sides a, b, and c of the nozzle hole within a specific range as described above. If this value is exceeded, this effect tends to decrease, so care must be taken when implementing it.

In addition, since the nozzle hole part of the present invention is made of ceramic, the nozzle hole can be accurately formed in a 7-shape shape, and ceramic has heat resistance, which prevents the needle valve from burning, the nozzle hole from clogging, and the valve from clogging. It becomes possible to completely eliminate the drawbacks of Sakaki's metallic fuel injection nozzle, such as excessive wear of the seat.

Furthermore, by setting the width of the grooves on the sides of the figure 7 shape to a specific range as described above, the above-mentioned mixing effect of air and fuel can be further enhanced.

Incidentally, in the above embodiment, an example of a fuel injection valve in which only the injection hole portion 30 was made of ceramic material was shown, but the present invention is not limited to this embodiment. It goes without saying that it can also be applied to items made of ceramic materials.

Furthermore, the fuel injection nozzle according to the present invention can be made lightweight, and the ceramic material has nozzle holes 70 in the molded product before sintering.
Since the pores can be pre-drilled and then sintered, it is possible to form a precise figure-7 nozzle hole as described above.

[Brief explanation of the drawing]

FIG. 1 is a partially broken side sectional view of a conventional fuel injection nozzle, FIG. 2 is a front view of the nozzle hole of the same injection nozzle, and FIG. 3 is a partially broken side view of a fuel injection nozzle according to an embodiment of the present invention. A side view, FIG. 4 is an enlarged sectional view of the tip of the injection nozzle,
FIG. 4A is an enlarged front view of a nozzle hole formed in a nozzle hole portion located at the tip of the same injection nozzle. Moreover, FIG. 5 is a diagram showing a state in which fuel is injected into the combustion chamber from the nozzle according to the present invention, and FIG. Diagram 7 explaining the state where air is involved
The figure shows how the effective average pressure and smoke change with respect to the fuel equivalence ratio. 1.10... Fuel injection nozzle, 2... Cylinder head, 3... Tip, 30... Nozzle hole, 4... Combustion chamber, 5... Needle valve, 6... Valve body, 7.70...・Nozzle hole, 8...
Valve seat part, 9... Nozzle nut, 11-... Keyway, 6a19a... Threaded part. Agent Patent Attorney Makoto Ogawa − Patent Attorney Ken Noguchi Teru Patent Attorney Kazuhiko Saishita (lO) Figure 1 Figure 2 Figure 3 Procedural Amendment (Forms) Dear Commissioner of the Japan Patent Office “″”゛“°″′” °“°゛1,・Smallness of the plot 11F (W5F1 Patent Application No. 23986 C:2,
Name of the invention Fuel injection nozzle for diesel engine 4, Agent 11 Location: 31'll Nishishibashi, Minato-ku, Tokyo 105
: + number 3; No change in pericabbil content).
905 Procedural Amendment 1, Indication of Case 1982 Patent Application No. 23986 2,
Name of the invention: Fuel injection V-nozzle for diesel engines 3. Relationship with the case of the person making the amendment Patent applicant's address (residence) Name (017) Isuy Automobile Co., Ltd. Kyoto Ceramic Co., Ltd. 4, Agent Address: Pelican Building 6, 3-3-3 Nishi-Shinbashi, Minato-ku, Tokyo 05/05 Subject of amendment Specification (full text), Chibi drawings (Figures 5 and 6 (b)) Specification 1, Invention Name: Fuel Injection Nozzle 2 for Diesel Engine, Claims: At least a nozzle hole provided in the nozzle hole portion located at the tip of the valve body is formed in a 7-shaped cross section, and a slit forming this nozzle hole is formed. 2 sides to the cylinder head side, and the other 1 side to the cylinder head side.
A fuel injection nozzle for diesel engines characterized by its sides facing toward the piston. Fuel injection nozzle for engine. 3. Detailed Description of the Invention The present invention relates to an improvement of a fuel injection nozzle that is installed in a diesel engine or the like and injects fuel into a combustion chamber. FIG. 1 is a partially cutaway side view (1) showing the structure of a fuel injection nozzle l installed in a conventional diesel engine. The cylinder head 2 is mounted so that the tip 3 faces the combustion chamber 4, and is configured to inject fuel 11f into the combustion chamber 4. In this type of fuel injection nozzle 1, a valve body 6 into which a needle valve 5 is slidably fitted is integrally made of heat-resistant steel up to the tip 3 where a nozzle hole 7 is formed. In most cases, the cross section 7s is circular, as shown in FIG. 2, for ease of processing. Therefore, the fuel injection 11 injected into the combustion chamber 4 from the nozzle hole 7
Since the surface area of f is small, the fuel spray in the center is dense,
There was a drawback that the outer circumferential portion became thinner, and homogeneous mixing with the air flow within the combustion chamber 4 could not be obtained, and smooth combustion could not be obtained. In addition, in order to eliminate the above-mentioned drawbacks, a nozzle has been proposed in which the nozzle hole is configured with a linear slit, and the fuel injection $1f is injected in a plate shape (2) to increase the contact area with the air. However, the fuel spray injected from this linear slit is weak and tends to be split in the center by swirls, and the fuel spray becomes discontinuous at these split points, delaying combustion, resulting in This had the disadvantage of lower combustion efficiency. Furthermore, in the case of a nozzle with a straight injection hole, the slit must be made long in order to obtain the required amount of fuel spray, and if the slit becomes too long, the strength of the nozzle tip will decrease and However, there was a drawback in that space was restricted in arranging the nozzle holes. Another problem with conventional fuel injection nozzles is that the shape of the fuel spray does not correspond to the distribution of air within the combustion chamber. In other words, on the cylinder head side and the piston combustion chamber side, the former is much more abundant than the latter, but the publication of fuel spray is not always like this, which means that the air and combustion (3) This causes uneven mixing with the fuel spray, and also causes a decrease in combustion speed and output. The present invention was obtained in order to eliminate the drawbacks of the conventional fuel injection nozzle, and the cross section of the nozzle hole provided at the tip of the valve body is formed into a figure 7 shape, and this nozzle hole is Place the two sides of the slit to the cylinder head side,
The present invention provides a fuel injection nozzle for a diesel engine in which the other side (edge) faces the piston side. The present invention will be described in detail below with reference to the drawings. FIG. 3 is a partially cutaway sectional view showing an embodiment of the fuel injection nozzle according to the present invention, FIG. 4 is an enlarged sectional view of the tip of the fuel injection nozzle in the same embodiment, and FIG. FIG. 3 is an enlarged front view of a nozzle hole provided at the tip. In the present invention, the injection hole portion 30 at the tip of the valve body 6 of the fuel injection nozzle 10 is made of a ceramic material, and
After inserting the key 11 into the key groove 61 (11) formed on the outer periphery to position the valve body 6 and the nozzle hole 3o, fit the nozzle nut 9 from below the nozzle hole 3o, The threaded part 9a is connected to the threaded part 6 of the valve body 6.
a, and is further attached to the cylinder head 2 (FIG. 3) of a diesel engine, indicated by a two-dot chain line, so that the nozzle hole portion 30 faces the combustion chamber 4. The ceramic material constituting the nozzle hole portion 30 may be a silicon nitride (Si3N, '') sintered body having the physical properties listed in Table 1 or a sialon made of silicon nitride containing an aluminum oxide (AI, O8) component. Sintered bodies are the most suitable ceramic materials.As is clear from Table 1, silicon nitride sintered bodies have properties that are much superior to metal materials and conventional alumina ceramics in terms of high-temperature strength, and are also less thermally resistant. The nozzle hole portion 3o of the fuel injection nozzle has extremely high thermal shock resistance, has a small coefficient of thermal expansion, and has low thermal conductivity.
This is the best choice for this configuration. An important point in the present invention is that the shape of the nozzle hole 7o provided in the nozzle hole portion 30 of the fuel injection nozzle (5) 10 is formed with a 7-shaped slit, and the slit forming this nozzle hole 7o is The two middle sides are on the cylinder head 2 side, and the other side (edge)
is located at the point facing the top side of the piston. Fig. 4A shows an enlarged view of the nozzle hole 7o. This nozzle hole has a flat slit in the shape of a figure 7 consisting of sides asbsC, and sides a and b are located on the 2nd side of the cylinder head, and C
is formed towards the top of the piston. The ratio between the width S and the length of the side a s b s C is preferably determined as follows, taking into consideration a number of experimental results. Inner=L/2~L15 By making the nozzle hole 7o into a figure 7 shape as described above, the fifth
As shown in the figure, the upper sides a and b are 1ia' and b.
' collides inward from the piston combustion chamber outlet, and the spray 11c'' on one side C at the bottom of the nozzle hole is distributed along the combustion chamber wall. Figures 6A and B show the state of fuel spray according to the present invention. This is a comparison between a Y (6) shaped nozzle hole and a normal round nozzle hole, and in the case of the fuel injection nozzle according to the present invention, the surface area of the outer periphery of the fuel spray IB (spray) S is Increased spout 1lIS
It can be seen that the air introduction rate shown by the arrow in any cross section perpendicular to the direction of O movement is greatly increased compared to the conventional round nozzle shown in FIG. 6B. Incidentally, the fuel injected from nozzle holes with the same cross-sectional area is 19! Regarding S, the air contact area in any cross section between a nozzle hole with a figure 7 shape and a nozzle hole with a round shape is 1.5 to 1. It is 5 times more. = FIG. 7 is a diagram showing the relationship between fuel equivalence ratio, smoke, and output. Curve Y shows data for the fuel injection nozzle according to the present invention, and curve R shows data for a conventional nozzle. According to FIG. 7, it can be seen that the average effective pressure Pme of the straight line Y representing the data of the nozzle of the present invention increases and the smoke decreases compared to the curve R representing the data of the conventional nozzle. (7) Furthermore, the effect of this improvement is remarkable in the diagonally shaded area between the two convex lines, where the fuel equivalent is large. On the other hand, since the tip of the nozzle, particularly the nozzle hole 30, is in direct contact with the flame, it tends to reach a very high temperature, and as the temperature increases, sludge and the like are generated. Therefore, it is better to improve the surface accuracy so that the contact part 32 between the nozzle hole part 30 and the main body 6 has good heat conduction, or to insert a material with good heat conduction such as copper into this contact part 32. . As described above, the present invention comprises the nozzle hole 70 provided in the nozzle hole portion 30 of the fuel injection nozzle with a slit having a 7-shaped cross section, and furthermore, the two sides a and b of the nozzle hole 70 are directed toward the cylinder head side. , the remaining side C is oriented toward the piston combustion chamber. Therefore, as shown in FIG. 5, the upper two sides a of the nozzle hole 70,
The fuel sprays a" and b' caused by b collide inside the outlet of the piston combustion chamber 4, and the spray @c" from one side C at the bottom is distributed toward the bottom of the combustion chamber, so the fuel spray forms a figure 7. As shown in Figure 6, it is possible to promote the introduction of air from the connecting part of the three sides of this (8), thus improving the mixing state of air and atomized fuel. Since it is possible to improve the combustion efficiency, it is possible to improve the combustion efficiency. The fuel spray injected from conventional fuel injection nozzles formed in a straight or slit shape has a weak stiffness, and the fuel spray is divided into multiple parts due to the swirl effect, resulting in a delay in ignition. The figure 7-shaped fuel spray injected from the figure 7-shaped nozzle hole 70 is in a state where the section modulus appears to have increased, so the fuel spray becomes stiffer.
The swirl prevents this fuel spray from breaking up easily, thereby preventing ignition delays and increasing combustion efficiency. Furthermore, in the present invention, the shape of the nozzle hole 7o is particularly shaped into a 7-shape, with two sides located on the cylinder head 2 side and the other side on the top side of the piston. Since one side is located on the side with fewer sides, it is possible to obtain a distribution of fuel spray commensurate with the amount of air (9), increasing combustion efficiency and increasing the output of the diesel engine. can. Furthermore, by making the nozzle hole part 30 made of ceramic, the nozzle hole 70 can be accurately formed in a 7-shape shape, and ceramic has heat resistance, so it can prevent seizure of the needle valve.
It becomes possible to completely eliminate the drawbacks of conventional metal fuel injection nozzles, such as clogging of the nozzle holes and excessive wear of the valve seat. In the above embodiment, an example of the fuel injection valve 1o was shown in which only the injection hole portion 3o was made of a ceramic material, but the present invention is not limited to this embodiment, and for example, the valve body 6
It goes without saying that this can also be applied to objects made of ceramic materials. Furthermore, the fuel injection nozzle 6 according to the present invention can be made lightweight, and the ceramic material has nozzle holes 7 in the molded product before sintering.
Since the pores can be sintered after pre-drilling the pores as 0, it is possible to form the accurate 7-shaped nozzle hole 70 as described above. (10) 4. Brief description of the drawings Fig. 1 is a partially cutaway side sectional view of a conventional fuel injection nozzle, Fig. 2 is a front view of the nozzle hole of the same injection nozzle, and Fig. 3 is a diagram showing the implementation of the present invention. A partially cutaway side view of the fuel injection nozzle in the example, FIG. 4 is an enlarged sectional view of the tip of the injection nozzle,
FIG. 4A is an enlarged front view of a nozzle hole formed in a nozzle hole portion located at the tip of the same injection nozzle. Moreover, FIG. 5 is a diagram showing a state in which fuel is injected into the combustion chamber from the nozzle according to the present invention, and FIG. FIG. 7, which is a diagram explaining the state, is a diagram showing a situation in which the effective average pressure and smoke change with respect to the fuel equivalence ratio. 1.10... Fuel injection nozzle, 2... Cylinder head, 3... Tip, 30... Nozzle hole, 4... Combustion chamber, 5... Needle valve, 6... Valve body, 7.70...・Nozzle hole, 8...
Valve seat part, 9... Nozzle nut, (11) 11... Keyway, 6a, 9a... Threaded part. Agent Patent Attorney Shin Ogawa − Patent Attorney Kensho Noguchi Patent Attorney Kazuhiko Saishita (12) (13)

Claims (1)

[Claims] At least the nozzle hole section located at the tip of the valve body is made of a ceramic material, and the nozzle hole provided in this nozzle hole section is formed into a figure 7 shape, and two of the slits forming this nozzle hole are formed. A fuel injection nozzle for a diesel engine, characterized in that one side faces the cylinder head side and the other side faces the piston side, -