JPS58143164A - Fuel injection nozzle for engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a fuel injection nozzle installed in an engine, particularly a diesel engine, for injecting 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 shown by a dotted line is fitted with a tip 3 having an injection hole 7 facing a combustion chamber 4 (1), and is configured to inject injected fuel f into the combustion chamber 4. ing.

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.

Also, 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 7s is changed during processing as shown in Fig. 2.
In most cases, the shape 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 smooth flow. The drawback was that combustion was not achieved.

(2) 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 a ceramic material, and the shape of the nozzle hole is formed into a T-shape, and the side of this T-shaped nozzle hole is placed on the cylinder head side. The first feature is that the vertical side of the piston is located 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 horizontal and vertical sides of the nozzle hole in order to efficiently diffuse the atomized fuel.

The present invention will be described in detail below with reference to the drawings. Figure 3 is a partially cutaway sectional view showing an embodiment of the fuel injection nozzle according to the present invention, and Figure 4 is a view of the tip of the fuel injection nozzle in the same embodiment. FIG. 4A is an enlarged sectional view, and FIG. 4A is an enlarged front view of the nozzle hole provided at the tip of the fuel injection nozzle.

(3) In the present invention, the nozzle hole 60 at the tip of the valve body 6 of the fuel injection nozzle 1o is made of a ceramic material, and
After positioning between the valve body 6 and the nozzle hole 6o by inserting the key 62 into the key 161 formed on the outer periphery thereof, the nozzle nut 9 is fitted from below the nozzle hole 6o,
The threaded part 91 is fitted into the threaded part 63 of the valve body 6, and then the cylinder head 2 of the diesel engine shown by the two-dot chain line is fitted.
(FIG. 3), the nozzle hole section 60 is installed so as to face the combustion chamber 4.

An important point in the present invention is that the nozzle hole portion 60 of the fuel injection nozzle 10 is made of ceramic, and the nozzle hole 7o is formed into a T-shape by taking advantage of the characteristics of this ceramic material.

FIG. 4A shows an enlarged view of the nozzle hole 70. This nozzle hole forms a T-shaped flat groove consisting of a horizontal side a and a vertical side. Lateral and longitudinal edges are formed towards the top of the piston.

The width S of the vertical and horizontal sides a and b and the length of the horizontal side 4) The ratio should be determined as follows.

S=L/8 to L/2 It is preferable that the horizontal side and the vertical side are arranged inside the outline of the square.

By making the nozzle hole 70 T-shaped as described above, the fifth
Spray a by side a as shown in the figure.

The piston collides with the inside of the combustion chamber outlet, and a vertical jet @b' is distributed along the combustion chamber wall.

Figure 6 ASB compares the state of fuel spray between the T-shaped nozzle hole of the present invention and a normal round nozzle hole. S (spray) The surface area of the outer periphery of F increases, and the air introduction rate shown by the arrow in an arbitrary cross section perpendicular to the direction of travel of spray @ F increases to 6th.
Compared to the case of the round nozzle hole of the conventional nozzle in Figure B, 1.
It can be seen that there is a significant increase of 6 to 5.2 times.

Incidentally, regarding the spray F injected from the nozzle holes with the same cross-sectional area, the area of air contact (5) at any cross section between the T-shaped nozzle hole and the round nozzle hole is T 1. Those with a letter shape are better than those with a round shape.
It is 5 to 5 times more.

FIG. 7 is a diagram showing the relationship between fuel equivalence ratio, smoke, and the way smoke is ejected. Curve T 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 Pea is increased and the smoke is reduced in the straight line T representing the data of the nozzle of the present invention compared to the curve R representing the data of the conventional nozzle.

Furthermore, the effect of this improvement is remarkable in the hatched area M between the two lines, where the fuel equivalent is large.

On the other hand, since the tip of the nozzle, especially the nozzle hole 6o, is in direct contact with the flame, it easily becomes very high temperature. It is preferable to improve the surface precision so that the contact portion 64 has good heat transfer, or to insert a material such as copper that has good heat transfer into this contact portion 64.

The ceramic material for the nozzle hole 3° (6) constituting the fuel injection nozzle of the present invention may be a sintered body of silicon nitride (Si3 N4) having the physical properties listed in Table 1, or a sintered body of silicon nitride with aluminum oxide (^). Sialon sintered body containing components 12Q and ) is the most suitable ceramic material.

As is clear from Table 1, silicon nitride sintered bodies have properties that are much superior to metal materials in terms of high-temperature strength.
Furthermore, it has extremely high resistance to thermal shock, has a small coefficient of thermal expansion, and has a low coefficient of thermal conductivity, making it a suitable material for the construction of the injection hole portion of a fuel injection nozzle.

In the present invention, as described above, the nozzle hole portion 60 of the fuel injection nozzle is made of ceramic, and the nozzle hole 70 provided in the nozzle hole portion 60 has a T-shaped cross section, and the side a of the nozzle hole is placed on the cylinder head side. It is distinctive in that the vertical side faces the piston combustion chamber.

Therefore, as shown in FIG.
18' collides with the inside of the outlet of the piston combustion chamber 4,
Since the jet @b' is distributed along the vertical sides toward the bottom of the combustion chamber 4, 1!1ilI is distributed spreading out in three directions in a T-shape, so as shown in FIG. It is possible to promote the introduction of air from the joint portion, and therefore, it is possible to improve the mixing state of the air and the sprayed fuel, so that the combustion efficiency can be improved.

In order to further increase the above effects, the ratio of the width S of the horizontal side a and the vertical side of the nozzle hole to the length of the horizontal side can be set within a specific range as described above. Preferably, if it is out of this range, the 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 is formed in a T-shape and the direction of the nozzle hole is specified, so that an accurate nozzle hole can be obtained and the heat resistance is a characteristic of ceramic. Therefore, it is possible to completely eliminate the drawbacks of conventional metal fuel injection nozzles, such as seizure of the needle valve, clogging of the nozzle hole, and excessive wear of the axle part.

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

In the present invention, since the nozzle hole portion is made of a ceramic material, it is possible to make small holes as nozzle holes in the molded product before sintering, and then to sinter the product. It is easy to form, and the roughness of the wall of the nozzle hole is 0.
．． Since the time can be set to 8 seconds or less, it is possible to reduce the resistance when the fuel passes through this nozzle hole.

Incidentally, in the above embodiment, an example of a fuel injection nozzle in which only the injection hole portion is made of ceramic or resin material was shown, but the present invention is not limited to this embodiment. For example, the valve body may be made of ceramic material. It goes without saying that it can also be applied to structured objects.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side sectional view of a conventional fuel injection nozzle, and FIG. 2 is a front view of the nozzle hole of the same injection nozzle. 3rd FI! J is the fuel injection number (9) in the embodiment of the present invention.
) (8) A partially broken side view of the nozzle, Figure 4 is an enlarged sectional view of the tip of the injection nozzle, and Figure 4A is the same section. FIG. 3 is an enlarged front view of an X-shaped nozzle hole. 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. 6 is a diagram showing a T-shaped nozzle hole of the nozzle according to the present invention and a conventional round nozzle hole. 7th WJ is a diagram illustrating the effects of the present invention, and is a diagram illustrating a situation where 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, 9... Nozzle Nand, 61... Keyway, 62... Key, 63.91... Threaded part. (10) Figure 1 Figure 2 Figure 3 Figure 4 Procedural amendment (method) Dear Commissioner of the Patent Office “”””””””°°”1. Indication of the case 1982 Patent Application No. 23988 +; 2. Name of the invention Fuel injection nozzle for engine 4. Agent 11 Address: 3-1 Nishi-Shinbashi, I81, Tokyo 105
'lla number: Cow; Pelican Building Ogawa/No 1111il
Inside the International Patent Office ('di story 431 5361) content unchanged). Procedural Amendment 1, Indication of Case 1982 Patent Application No. 23988 2,
Name of the invention Fuel injection nozzle for engines 3, Relationship to the amended case Patent applicant 4, Agent Address Pelican Building, Ogawa Fukuchi International Patent Office, 3-3-3 Nishi-Shinbashi, Minato-ku, Tokyo 105 Inside the office (telephone 431
-5361) (Attachment) Description 1, Name of the invention Fuel injection nozzle 2 for an engine, characterized in that the horizontal side of the claim is oriented toward the cylinder head side and the vertical side is oriented toward the piston side. Fuel injection nozzle for engines. material injection nozzle. 3. Detailed Description of the Invention The present invention relates to an improvement in a fuel injection nozzle installed in an engine, particularly a diesel engine, for injecting 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 tip end 3 having a nozzle hole 7 is attached to the cylinder head 2 so as to face the combustion chamber 4, and is configured to inject the injected fuel f into the combustion chamber 4. 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. In most cases, the cross-sectional shape 7S is circular, as shown in FIG. 2, for ease of workability. Therefore, since the surface area of the fuel spray f injected into the combustion chamber 4 from the nozzle hole 7 is small, the fuel spray is dense at the center and thinner at the outer periphery, resulting in uniform mixing with the air flow inside the combustion chamber 4. There was a drawback that smooth combustion could not be obtained. Furthermore, in order to eliminate the above-mentioned drawbacks, a nozzle has been proposed in which a linear slit is constructed as a nozzle hole and the fuel spray is injected in a plate shape to increase the contact area with the air. (2) The fuel spray injected from the slit is weak and tends to be split in the center by swirls, and combustion becomes discontinuous at these split points, causing a delay in combustion, resulting in a decrease in combustion efficiency. There were drawbacks. Furthermore, in the case of a nozzle with a straight nozzle hole, the slit must be made long to obtain the required amount of fuel spray, and if the slit becomes too long, the strength of the nozzle tip will decrease. This method has the disadvantage of being subject to space constraints when 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. That is, on the cylinder head side and the piston combustion chamber side, there is much more fuel spray on the former side than on the latter side, but the distribution of fuel spray is not necessarily like this. This causes uneven mixing of air and fuel spray and causes a reduction in combustion speed. (3) 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 T-shape, and this nozzle is The first feature is an engine fuel injection nozzle in which the horizontal side of the slit forming the hole is oriented toward the cylinder head and the vertical side is oriented toward the piston. A second feature of the fuel injection nozzle for an engine is that a portion thereof is made of a ceramic material. The present invention will be described in detail below with reference to the drawings. FIG. 3 shows an embodiment of a 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. 4A is an enlarged front view of the nozzle hole provided at the tip of the fuel injection nozzle. In a preferred embodiment of the invention, the fuel injection nozzle 10
The nozzle hole section 60 at the tip of the valve body 6 is made of a ceramic material, and a key 62 is inserted into the key groove 61 formed in (4) on the outer periphery of the valve body 6 to connect the valve body 6 and the nozzle hole section 60. After positioning the nozzle hole part 60
Fit the nozzle nut 9 from below, fit its threaded part 91 to the threaded part 63 of the valve body 6, and then attach the nozzle hole part 60 to the cylinder head 2 of the diesel engine (FIG. 3) shown by the two-dot chain line. is mounted so as to face the combustion chamber 4. An important point in the present invention is that the shape of the nozzle hole 70 provided in the nozzle hole portion 60 of the fuel injection nozzle IO is formed into a T-shape, and the horizontal side of the slit forming this nozzle hole 70 is formed in the cylinder head 2. on the side, and at a point with the vertical side facing the piston side. FIG. 4A shows an enlarged view of the nozzle hole 70, which has a T-shaped flat groove or slit consisting of a horizontal side a and a vertical side. On the head 2 side, the vertical side is also formed towards the top of the piston. The ratio of the width S of the vertical and horizontal sides a and b to the length of the horizontal side is preferably determined as follows, taking into consideration a large number of experimental results. (5) S=L/8 to L/2 Note that it is preferable that the horizontal and vertical sides are arranged inside the outline of the square. As mentioned above, the nozzle hole 70 is formed by combining the horizontal side a and the vertical side
By forming the piston into a letter shape, as shown in FIG. 5, the spray a° from the horizontal side a collides inward from the outlet of the piston combustion chamber, and the spray b′ from the vertical side is distributed along the combustion chamber wall. As mentioned above, the amount of air on the cylinder head side is significantly larger than the amount of air on the piston combustion chamber side, but in the present invention, the shape of the fuel spray is configured especially in accordance with this air distribution amount. There is. Figures 6A and 6B compare the state of fuel spray between the T-shaped nozzle hole of the present invention and a normal round nozzle hole. The surface area of the outer periphery of the spray F increases, and the air introduction rate shown by the arrow in any cross section perpendicular to the direction of travel of the spray F increases compared to the case of the round nozzle hole of the conventional nozzle shown in Figure 6B. and 1.6
It can be seen that there is a significant increase of ~5.2 times (6). Incidentally, fuel injection 1lI injected from nozzle holes with the same cross-sectional area
Regarding F, the contact area of air in any cross section between a T-shaped nozzle hole and a round nozzle hole 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, with curve T representing data for the nozzle of the present invention, and curve @R representing data for the conventional nozzle. According to the above-mentioned FIG. 7, it can be seen that the average effective pressure Pre increases and the smoke decreases in the data of the nozzle of the present invention, which is straight @T, compared to the curve R showing the data of the conventional nozzle. . Furthermore, the effect of this improvement is remarkable in the hatched area M between the two lines, where the fuel equivalent is large. On the other hand, the tip of the nozzle, especially the nozzle hole 60, is in direct contact with the flame and therefore tends to become very hot, and as the temperature increases, scratches and the like occur. Therefore, the contact portion 64 between the nozzle hole portion 60 and the main body 6 has good heat transfer (7).
4. It is best to insert a material with good heat transfer such as copper. As the ceramic material for the nozzle hole portion 30 constituting the fuel injection nozzle of the present invention, silicon nitride (Sis Na) sintered body having the physical properties listed in Table 1 or silicon nitride with an aluminum oxide (Ah Os) component may be used. The most suitable ceramic material is a sialon sintered body. As is clear from Table 1, silicon nitride sintered bodies have properties that are several orders of magnitude better than metal materials in terms of high-temperature strength.
In addition, it has extremely high thermal shock resistance against heat shock, has a small thermal expansion coefficient, and has a small thermal conductivity, making it a material suitable for the construction of the injection hole portion of a fuel injection nozzle. As described above, the present invention is directed to the nozzle hole portion 60 of the fuel injection nozzle 1o.
(8) The nozzle hole 70 provided in the engine has a T-shaped cross section, and the horizontal side a of the nozzle hole is directed toward the cylinder head, and the vertical side is directed toward the piston combustion chamber. Therefore, as shown in FIG. 5, the jet 1a' from the side a of the nozzle hole 70 collides with the inside of the outlet of the piston combustion chamber 4,
Further, since the spray @b' is distributed along the vertical sides toward the bottom of the combustion chamber 4, the distribution of the fuel spray corresponds to the amount of air in the combustion chamber. Furthermore, since this fuel spray is distributed in a T-shape while spreading in three directions, the contact area between the air and the fuel spray increases, and as shown in Figure 6, it is possible to introduce air from the joint between the two vertical and horizontal sides. It becomes possible to promote this. Therefore, the fuel spray is distributed in accordance with the distribution of air in the combustion chamber, and by forming the T-shaped slit, it is possible to improve the mixing state of the fuel spray, air, and fuel spray. It becomes as if the section modulus has increased, making the fuel stiffer, and ignition occurs continuously without being broken up by swirls like fuel spray injected through a simple linear slit. The ignitability is improved, and (9) combustion efficiency can be improved accordingly. Furthermore, by making the nozzle hole part of the present invention made of ceramic, forming the nozzle hole in a T-shape, and specifying the direction of the nozzle hole, it is possible to accurately specify the direction of fuel spray. Since ceramic is heat resistant, it can completely eliminate the drawbacks of conventional metal fuel injection nozzles, such as seizure of the needle valve, clogging of the nozzle hole, and excessive wear on the valve seat. Become. Furthermore, by configuring the nozzle hole part with a ceramic material, it is possible to make small holes as nozzle holes in the molded product before sintering and then sinter it, so that the T-shaped shape of the nozzle hole can be reduced. Since it is easy to form and the roughness of the wall of the nozzle hole can be set to 0.8s or less, it is possible to reduce the resistance when the fuel passes through the nozzle hole. In the above embodiment, an example of a fuel injection nozzle in which only the injection hole portion is made of a ceramic material is shown, but the present invention is not limited to this embodiment (10). For example, the valve body may be made of a ceramic material. It goes without saying that it can also be applied to things made up of . 4. Brief Description of the Drawings FIG. 1 is a partially cutaway side sectional view of a conventional fuel injection nozzle, and FIG. 2 is a front view of the nozzle hole of the same injection nozzle. FIG. 3 is a partially cutaway side view of a fuel injection nozzle according to an embodiment of the present invention, FIG. 4 is an enlarged sectional view of the tip of the injection nozzle, and FIG. 4A is an injection nozzle located at the tip of the injection nozzle. It is an enlarged front view of the X-shaped nozzle hole formed in the hole part. 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. 6 is a diagram showing a T-shaped nozzle hole of the nozzle according to the present invention and a conventional round nozzle hole. FIG. 7 is a diagram illustrating the effects of the present invention, and is a diagram illustrating a situation in which the effective average pressure and smoke change with respect to the fuel equivalence ratio. 1.10... Fuel injection nozzle, (11) 2... Cylinder head, 3... Tip, 30... Nozzle hole, 4... Combustion chamber, 5... Needle valve, 6... Valve body, 7 .70... Nozzle hole, 8...
Valve seat, 9...nozzle nut, 61...keyway, 62...key, 63.91...threaded part. Agent: Patent Attorney Shin Ogawa − Patent Attorney Ken Noguchi Teru 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 T-shape, and the lateral side of the slit forming this nozzle hole is formed. A fuel injection nozzle for an engine characterized by having a side facing toward the cylinder head and an edge facing toward the piston.