JPH08284776A - Air-assisted injector - Google Patents

Abstract

PURPOSE: To reduce the number of machining processes and parts to be used and improve corrosion resistance by integrally-forming an atomizer and a nozzle for injecting fuel from a fuel injection hole and using the same material for them. CONSTITUTION: In an air-assisted injector, magnetic force is generated inside a coil 8 when electric current flows through the coil 8, and draws a plunger rod 2 in the direction of an adjuster 1 to move a ball valve 4 away from a nozzle seat surface 11, thereby injecting fuel from a fuel injecting hole 6. For this, a nozzle-atomizer 5 in which a nozzle and an atomizer are integrally- formed is provided. An air hole 9 is opened between the outer wall of the nozzle body and the internal surface of a mixing chamber 10, which allows an air flow to collide with fuel from the diameter direction and then the air flow and fuel to mix in a mixing chamber zone in the nozzle in the nozzle body. The inner diameter of the mixing chamber zone is formed so as to be smaller than that of a zone on the engine cylinder side in the nozzle and larger than that of the fuel injection hole 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-assisted injector for an automobile, and in particular, a nozzle and an atomizer are made of the same material and have an integrated structure, or a nozzle having the function of an atomizer is used to reduce the number of parts and the manufacturing process to reduce the cost. The present invention relates to an air-assisted injector which is excellent in corrosion resistance and swelling resistance to a fuel containing a corrosive additive such as a gasoline-alcohol mixed fuel and having a strong corrosiveness and swelling property.

[0002]

2. Description of the Related Art Conventionally, an atomizer is connected to a nozzle as a separate structure, and both of them are used by being welded or tightly joined by press fitting.

The nozzle material is repeatedly contacted and non-contacted with the ball valve, so that the contact surface hardness and corrosion due to fuel, etc. are prevented, and JIS standard SUS440C, S is used.
It is made of martensitic stainless steel such as US420J2, and Japanese Patent Laid-Open No. 6-58218 discloses the use of highly corrosion resistant martensitic stainless steel for a ball valve or a nozzle body.

It is desirable that the atomizer material is excellent in corrosion resistance and swelling resistance and lightweight in order to prevent corrosion due to fuel and the like and to prevent falling off during use.
So-called No. 2000 series aluminum alloys such as No. 7 or the like, those obtained by subjecting those aluminum alloys to chromate treatment, or plastics such as PPS (polyphenylene sulfide) were used.

[0005]

However, such a separate structure has a problem of an increase in the number of parts and the assembling process, and the required characteristics of the two are different. Therefore, for example, a martensitic stainless steel is used for the nozzle. With steel joined to the atomizer using aluminum alloy etc.,
Since it becomes a dissimilar metal, if it is repeatedly used, galvanic corrosion occurs at the joint portion of the dissimilar metals, and the coupling between the nozzle and the atomizer is impaired.

Further, the nozzle and the atomizer are required to have a strict coaxiality after they are respectively coupled.

Therefore, there has been a problem that the yield is lowered after the bonding. In other words, after the assembly process, the strict regulation of the coaxiality is not met, and there is a problem of yield reduction due to defective coaxiality, and in the product reproduction and quality control, the defectiveness in the final process is a productivity problem.

Further, the conventional specifications are intended only for gasoline fuel having a low corrosiveness, and a gasoline-alcohol in which methanol or ethanol is mixed with gasoline is used as an exhaust gas cleaning agent or an octane number improving agent in Europe, the United States and Brazil. For fuels containing corrosive additives, such as mixed fuels (hereinafter referred to as alcohol fuels), the corrosion resistance of the parts of the atomizer, solenoid valve and nozzle that collide or slide with each other is insufficient. When used under alcohol fuel, there is a problem that the fuel leaks from itself and from the cylinder intake valve gap.

That is, there is a problem that the blowback gas containing a harmful corrosive component such as chlorine ion corrodes the fuel passage and the outer surface of the atomizer. When the fuel passage corrodes, the mixed state of the fuel and air deteriorates, so that the fuel is less likely to be atomized. As a result, the combustion efficiency deteriorates, and the concentration of harmful components such as HC in the exhaust gas doubles, which eventually leads to a problem of deterioration of the global environment.

Further, if corrosion further progresses, in the worst case, the atomizer may fall into the engine cylinder, causing seizure of the engine, which poses a serious safety risk.

When the atomizer is plastic, there is a problem of swelling due to alcohol fuel. When this swelling progresses, the stress increases in the fuel passage when the fuel flows,
It is expected that a crack will occur in the fuel passage, deterioration of the injection state and the same situation such as the atomizer dropping out will occur, which is a safety issue.

Japanese Unexamined Patent Publication (Kokai) No. 6-58218 discloses the use of highly corrosion-resistant martensitic stainless steel for a ball valve or nozzle body, but the corrosion resistance and hardness of the nozzle are examined. The atomizer was not considered.

The present invention has been made in view of the above-mentioned problems, and it is possible to reduce the number of processing steps, the number of parts, the coaxial defect and the corrosion resistance of the nozzle and the atomizer portion, thereby improving reliability and economy. Another object of the present invention is to provide an air-assisted injector with high safety.

It is another object of the present invention to provide an air-assisted injector having excellent corrosion resistance and swelling resistance even for a highly corrosive fuel containing a corrosive additive such as gasoline-alcohol mixed fuel.

[0015]

SUMMARY OF THE INVENTION An air assist injector according to the present invention has an electromagnetic valve that vibrates up and down by an electromagnetic suction mechanism and a fuel injection hole at the center, and the electromagnetic valve repeats collisions to cause the fuel injection hole to move. An air assist injector for an internal combustion engine, comprising an openable / closable nozzle and an atomizer for injecting fuel into the engine cylinder from the fuel injection hole, wherein the atomizer and the nozzle have an integral structure and are made of the same material. .

The air assist injector of the present invention comprises an electromagnetic valve that vibrates up and down by an electromagnetic suction mechanism, and a nozzle that has a fuel injection hole in the center and that opens and closes the fuel injection hole by repeated collisions of the electromagnetic valve. In the air-assisted injector for an internal combustion engine, the nozzle is provided with an air hole for supplying air to collide with the injected fuel.

The air assist injector of the present invention comprises an electromagnetic valve that vibrates up and down by an electromagnetic suction mechanism, and a nozzle that has a fuel injection hole in the center and that opens and closes the fuel injection hole by repeated collisions of the electromagnetic valve. In an air assist injector for an internal combustion engine, an air hole for supplying air to collide with injected fuel is provided in the nozzle, the inside of the nozzle has a mixing chamber where the injected fuel and the air collide, and the inside of the nozzle is It is characterized by having at least two stages of inner diameter.

The air assist injector of the present invention comprises an electromagnetic valve that vibrates up and down by an electromagnetic suction mechanism, and a nozzle that has a fuel injection hole in the center and that opens and closes the fuel injection hole by repeated collisions of the electromagnetic valve. The air-assisted injector for an internal combustion engine is characterized in that the nozzle is injection-molded and sinter-molded from metal powder and has air holes.

The air assist injector of the present invention comprises an electromagnetic valve which vibrates up and down by an electromagnetic suction mechanism, and a nozzle which has a fuel injection hole in the center and which opens and closes the injection hole by repeated collisions of the electromagnetic valve. In an air-assisted injector for an internal combustion engine, the fuel injected from the injection hole attached to the tip of the nozzle is collided with the air taken in from the air hole to atomize the fuel inside and from the fuel injection hole to the inside of the engine cylinder. An air-assisted injector for an internal combustion engine, comprising an atomizer for injecting fuel, characterized in that the atomizer is integrated with a nozzle.

In the air-assisted injector of the present invention, the nozzle of the air-assisted injector uses 300 pL of hydrochloric acid as a mixed fuel consisting of gasoline containing 30% by weight of methanol.
It is characterized by being a martensitic stainless steel showing a corrosion degree of 50 to 100 mg / dm ² day when immersed in a solution containing pm at room temperature for 24 hours.

The air-assisted injector of the present invention is characterized in that air is ejected in a nozzle of the air-assisted injector in a direction substantially opposite to the direction of ejection of fuel, and the fuel and the air are caused to collide with each other.

In the air assist injector of the present invention, fuel is spirally ejected in the nozzle of the air assist injector, and air is ejected from an air hole provided on the side surface of the nozzle in a direction substantially opposite to the ejection direction of the fuel. It is characterized in that it is ejected and the fuel and the air are caused to collide with each other.

In the air-assisted injector of the present invention, the nozzle is preferably made of martensitic stainless steel.

In the air-assisted injector of the present invention, the martensitic stainless steel contains C:
It is desirable that 0.2 to 0.5%, Cr: 12.0 to 15.0%, unavoidable impurities and the balance mainly consist of Fe. Further, it is desirable to contain Mo: 0.5 to 1.5% by weight. Furthermore, in weight%, Cu: 0.1
It is desirable to contain 1.0%.

[0025]

The reason for limiting the components of the stainless steel used in the air assist injector of the present invention will be described.

C is an element necessary for increasing the hardness by enabling the martensitic transformation of the matrix, and it is necessary to add 0.2% or more by weight% to it.
If it exceeds 0.5%, chromium carbide is formed, so that the chromium concentration of the matrix is lowered, and thus the corrosion resistance is deteriorated. Therefore, the range is 0.2% or more and 0.5% or less. From the viewpoint of corrosion resistance, the range of 0.2 to 0.45% is preferable, and the range of 0.25 to 0.45% is more preferable.

Cr is a basic element for imparting corrosion resistance, and the effect is exhibited by adding 12% by weight or more,
Even if added in excess of 15%, the effect is not improved and, conversely, chromium carbide is formed and a soft ferrite layer is formed, which deteriorates corrosion resistance and hardness. Therefore, the range is set to 12.0% or more and 15.0% or less. Here, in terms of corrosion resistance, the range of 12.5 to 15.0% is preferable, and the range of 12.5 to 14.0% is more preferable.

Mo is an element effective in improving the corrosion resistance to non-oxidizing acids such as chlorine ions, and at least 0.5% by weight, and 0.5% or more must be added to it. However, even if added over 1.5%, the effect is not further improved, and the hardness decreases and the cold forgeability deteriorates. Therefore,
It was set to 0.5% or more and 1.5% or less. Here, the range of 0.7 to 1.5% is preferable in terms of corrosion resistance, and 0.9 to 1.5
% Is more preferable.

Cu is effective in improving the corrosion resistance and hardenability of the material, and it is necessary to add 0.1% by weight or more of it. However, even if added over 1.0%, the effect is not improved any more, and conversely, the Ms point is lowered and the hardenability deteriorates. Therefore, the range is set to 0.1% or more and 1.0% or less. Considering hardenability, 0.3-
The range of 0.6% is preferable, and 0.4 to 0.6% is more preferable.

Ni has the effect of improving the corrosion resistance and workability of the material, and it is necessary to add 0.03% or more by weight%. However, even if added over 0.6%, the effect is not further improved, and conversely the workability is deteriorated. Therefore, the range is set to 0.03% or more and 0.6% or less. Considering corrosion resistance and workability, the range of 0.03 to 0.3% is preferable, and the range of 0.03 to 0.2% is more preferable.

In addition to increasing strength and toughness, Mn improves workability by forming MnS by combining with S which is an unavoidable impurity. It requires addition of 0.03% or more by weight. However, even if added over 0.75%, the effect is not further improved, and conversely the workability and corrosion resistance deteriorate. Therefore, 0.03% or more and 0.75%
The range was as follows. Considering corrosion resistance and workability, it is 0.
The range of 03-0.6% is preferable, and 0.3-0.6% is more preferable.

Si refines carbides and prevents the formation of reticulated carbides. It requires addition of 0.03% or more by weight. However, if it is added over 1.0%, the workability is deteriorated. Therefore, the range is set to 0.03% or more and 1.0% or less. Considering corrosion resistance and workability, the range of 0.3 to 0.7% is preferable, and 0.3 to 0.7% is preferable.
0.5% is more preferable.

Next, due to the economic downturn caused by the bursting of the bubble economy in H2 and the effects of the long-term yen recession, export industry companies have been forced to rationalize for survival, and thorough cost reduction for products is required. Is required. In particular, the automobile industry, which is a representative export industry in Japan, requires stricter measures than other industries, and some parts are required to reduce costs by 30% or more.

In order to meet such requirements, the most effective way is to reduce the number of parts by changing the design. But,
Conventional nozzles have collisions or sliding parts with solenoid valves,
It is necessary to have high hardness and high corrosion resistance, and therefore SU
Martensitic stainless steel such as S440C was used. On the other hand, since the atomizer does not have a collision or a sliding portion, it does not need to have high hardness. Therefore, it is required to be lightweight and workable, and an aluminum alloy such as A2017 or a plastic material such as PPS has been used. Then, they were separately manufactured and then joined by press fitting or the like.

The present invention intends to improve the corrosion resistance and the like by manufacturing the both of them which have different requirements in the same manner.

In order to produce both of them in an integrated structure, they must have high hardness, high corrosion resistance and workability.
Since the nozzle has a collision part or a sliding part with the solenoid valve, it is considered preferable to use martensitic stainless steel in terms of material.

However, when the atomizer and the nozzle are integrally manufactured from martensitic stainless steel, the shape becomes complicated, so that the conventional cutting method increases the number of processing steps rather than increasing the cost, and the cost increases. There is a problem that the merit of structuring is lost. That is, it is difficult to manufacture by a forging method which is a conventional nozzle manufacturing method in order to form an integrated structure.

As a result of the inventors' consideration of this point,
By applying the metal injection molding method (hereinafter referred to as MIM method), which can manufacture even complicated shaped parts without impairing strength and durability, the workability of the material is improved,
It has been found that the working process can be shortened and the working cost can be prevented from increasing.

In the MIM method, metal powder having a particle size of 200 μm or less is thoroughly mixed together with a carbonaceous binder or the like.
At this time, the particle size is preferably 100 μm or less.

Then, injection molding is performed by injecting into a molding die. Then, pre-sintering is performed while applying pressure in vacuum.
The mold pressure is about 20 to 60 MPa, and the pre-sintering temperature is about 600 to 800 ° C. At this time, the mold pressure is preferably in the range of 30 to 50 MPa, and the pre-sintering temperature is preferably in the range of 650 to 750 ° C. Further, the holding time of the temporary sintering temperature is preferably 10 minutes or more and 60 minutes or less.

After the preliminary sintering, the main sintering is carried out, but the main sintering temperature is 900 to 13 which is about 300 to 400 ° C. higher than the temporary sintering.
The range of 00 ° C is preferred. 1000-1200 degreeC is more preferable. Further, the holding time of the main sintering temperature is preferably 10 minutes or more and 60 minutes or less, which is equivalent to the holding time of the temporary sintering temperature.

By applying this MIM method, the problem of workability is solved, and the nozzle and atomizer having a complicated shape are manufactured without compromising the processing steps and cost reduction which are the advantages of the integrated structure. Is possible.

That is, it is possible to manufacture a nozzle and an atomizer which are made of the same material and have an integrated structure, and it is possible to obtain a nozzle and an atomizer which are excellent in workability and corrosion resistance and have high strength.

Since the nozzle and atomizer as described above are manufactured as an integral structure, the number of parts is reduced to that of the conventional nozzle:
The number of nozzles and atomizer: 1 and atomizer: 2 in total becomes 1 nozzle and atomizer: 1 and the number of parts can be reduced. Further, in terms of the processing step, the conventional joining process between the nozzle and the atomizer is omitted, and the problem of the misalignment of the coaxiality between the nozzle and the atomizer, which is important after joining, is solved.

Since the nozzle and the atomizer are integrated, there is no fear of the atomizer falling off, which could occur due to corrosion in the related art, and an air-assist injector with excellent safety can be provided. .

Further, even when a fuel having high corrosiveness and swelling property such as alcohol fuel, which has high strength, is excellent in workability and corrosion resistance, and is desired to be used in terms of environment, is used, The fuel passage and the outer surface of the fuel cell will not be corroded and the combustion efficiency will not be deteriorated.

Further, when an aluminum alloy atomizer and stainless steel are used as in the prior art, galvanic corrosion occurs between dissimilar metals, but in the present invention, the nozzle and atomizer do not become dissimilar metals to each other. Since the same material is used, galvanic corrosion can be prevented, and even if an alcohol fuel having low volume resistivity and high conductivity is used, galvanic corrosion can be prevented. Therefore, it is possible to provide an air-assisted injector excellent in cost and corrosion resistance.

Next, since it is manufactured by the MIM method, it is possible to easily form an air hole in the nozzle, and it is possible to add to the nozzle the function of colliding air with the jetted fuel, which is the function of the atomizer. At this time, it is desirable to reduce the inner diameter of the mixing chamber where the fuel and air collide, and the inner diameter on the side where the fuel is injected into the engine cylinder is
Larger size is desirable for fine dispersion of fuel.

Therefore, in the nozzle, it is desirable that the inner diameter of the mixing chamber through which the air hole communicates and the inner diameter on the side where fuel is ejected to the engine cylinder be different.

That is, it is desirable to reduce the inner diameter of the mixing chamber through which the air holes communicate, increase the inner diameter on the side where fuel is injected into the engine cylinder, and make the nozzle inner diameter a two-stage structure. At this time, the number of stages may be three or more in consideration of the flow of fuel, but it is desirable that the inner diameter be gradually increased from the fuel supply side to the nozzle to the jet side to the engine cylinder. With such a structure of the nozzle, although the shape is complicated, the collision of fuel and air can be performed easily and smoothly, and a finely pulverized fuel can be ejected to the engine cylinder.

[0051]

【Example】

 (Example 1) Hereinafter, the present invention will be described based on examples.

FIG. 1 is a sectional view of an air-assisted injector to which the present invention is applied, and FIG. 3 shows a nozzle and an atomizer having an integral structure.

The air-assisted injector has a spring 3 incorporated between the adjuster 1 and the plunger rod 2, and normally, the spring force of the spring 3 causes the ball valve 4 joined to the tip of the plunger rod 2.
Is pressed against the nozzle seat surface 11 of the nozzle body 5 to close the fuel injection hole 6. Fuel is the fuel supply hole 7
Supplied by pressurization.

Here, when a current flows through the coil 8, a magnetic force against the spring force is generated inside the coil 8, and the plunger rod 2 is attracted toward the adjuster 1,
Since the ball valve 4 is separated from the nozzle seat surface 11, fuel is injected from the fuel injection hole 6.

In the conventional air-assisted injector shown in FIG. 6, a single atomizer 21 is attached to a single nozzle 20 by welding or the like, and air is taken in from a single atomizer air inlet hole 23 that has a clearance between the single nozzle 20 and the single atomizer 21. Air flows through the single atomizer air hole 22 and the fuel and air collide in the single atomizer 21.

In such a conventional example, the O-ring 13 is
It was arranged closer to the engine cylinder than the fuel injection hole 6.

In this embodiment, as shown in FIGS. 1 and 3, the nozzle and the atomizer have an integrated structure.

As shown in FIG. 3, the fuel injected from the fuel injection hole 6 advances spirally when passing through the mixing chamber 10.
It is desirable to supply air from the direction opposite to the traveling direction of the fuel as much as possible. That is, this is to sufficiently mix the air taken in through the air holes 9 and the fuel. When this mixing is sufficiently performed, the fuel is further atomized and the combustion efficiency is improved.

The air holes 9 are connected from the outer wall of the nozzle body 5 to the inner surface of the mixing chamber 10, and the air flow 17 is
From the outer wall of the nozzle body 5 toward the inner surface of the mixing chamber 10, the fuel collides with the fuel. Due to this collision, the fuel is diffused and atomized.

In-nozzle mixing chamber region 1 in the nozzle body 5
8, fuel and air are mixed, but the inner diameter in this region is smaller than the inner diameter of the engine cylinder side region 19 in the nozzle and larger than the fuel injection hole 6.

Here, unlike the conventional example, the O-ring 13
When placed on the engine cylinder side of the fuel injection hole 6, it overlaps with the air hole 9, so it was installed at substantially the same position as the fuel injection hole 6 in the vertical direction.

In this embodiment, the inner diameter of the fuel injection hole 6 is φ.
0.8 mm, and the mixing chamber area 18 in the nozzle, that is,
The inner diameter of the mixing chamber 10 was φ2 mm. Further, the inner diameter of the engine cylinder side region 19 in the nozzle was φ10 mm, and the outer diameter of the nozzle body 5 was φ12 mm. Therefore, the inner surface of the nozzle body 5 has a two-step structure including the inner diameter of the mixing chamber 10 and the inner diameter of the engine cylinder side region 19 in the nozzle, and the inner diameter gradually increases from the fuel injection hole 6 to the engine cylinder side. . This two-stage structure may have three or more stages.

Here, the inner diameter of the mixing chamber 10 is 1.times. The inner diameter of the fuel injection hole 6 in order to sufficiently collide the fuel with the air.
It is preferably 5 times or more, but if it is too large, the fuel does not flow smoothly, so 10 times or less is preferable. That is, when the inner diameter of the fuel injection hole 6 is φ0.8 mm, φ1.2 m
m-φ8.0 mm is preferred. Furthermore, the inner diameter of the mixing chamber 10 is more preferably 2 to 5 times the inner diameter of the fuel injection hole 6. Further, it is preferable that the outer diameter of the nozzle body 5 is about ⅓ or less from the viewpoint of ease of processing.

The coaxiality between the inner diameter of the mixing chamber 10 and the inner diameter of the engine cylinder side region 19 in the nozzle is improved in accuracy by manufacturing it in an integrated structure.

The air holes 9 preferably have a diameter of about 0.8 mm, which is almost the same as the inner diameter of the fuel injection holes 6, and in order to improve the effect of collision with the fuel, the O-ring recess 15 is closer to the engine cylinder side region 19 in the nozzle. Then, the mixing chamber area 18 in the nozzle
It is preferably provided on the fuel injection hole 6 side inside. When miniaturization is sufficient and smoothness of flow is important, it may be provided on the engine cylinder side region 19 side in the nozzle. In this embodiment, it is provided at a position 2 mm from the fuel injection hole 6 side. When focusing on the miniaturization of the fuel, the position of about 1 to 3 mm is more preferable.

In the engine cylinder side region in the nozzle, the inner diameter was φ10.0 mm, but the wall thickness, which is the difference from the outer diameter, is appropriately about 1 mm.
5 to 2.0 mm is preferable. Further, on the engine cylinder side, the inner surface has a gentle C surface from the inner diameter to the outer diameter so that fuel is smoothly ejected.

Next, FIGS. 4 (a) and 4 (b) are cross-sectional views of a nozzle and an atomizer having an integral structure.

In this embodiment shown in FIG. 4A, the air holes 9
Four nozzles were provided from the side surface of the nozzle body 5 toward the center. The air holes 9 are preferably provided symmetrically on the cross section. Further, it is preferable to provide two or more, and 3 to 6
Is more preferable. At this time, the direction in which the air holes 9 are opened from the side surface of the nozzle body 5 directly determines the flow direction of the air. Therefore, it is preferable that the direction opposite to the fuel flowing in the spiral direction is satisfied. It may be inclined with respect to the center direction. That is, the air holes 9 may be tilted in the direction opposite to the direction of rotation of the fuel by about 0 to 30 ° so that the fuel and the air collide with each other as easily as possible.

For example, when the fuel is rotating as shown in FIG. 4 (b), it is desirable to tilt it in the direction opposite to the rotating direction. Here, three air holes 9 are provided at 60 ° intervals in order to make a contrast on the circular cross section. Also, it was tilted about 10 ° with respect to the center direction to facilitate collision with fuel.

The fuel thus atomized is injected from the fuel injection hole 6 toward the engine cylinder (not shown).

As described above, since the nozzle and the atomizer are integrated with each other, different kinds of metals are not formed, galvanic corrosion can be prevented, and corrosion resistance is improved.

Further, since the atomizer did not drop into the engine cylinder due to corrosion, it was possible to obtain an air-assisted injector having excellent safety.

Further, it has been found that the number of parts can be reduced, the number of processing steps can be reduced, especially the joining step can be omitted, and a low cost and high quality air assist injector can be obtained.

(Second Embodiment) Further, unlike the first embodiment, the air holes 9 may be inclined in the vertical direction as shown in FIG.

At this time, the position of the air hole 9 on the inner surface of the mixing chamber 10 is the same as that of the first embodiment, but by shifting the position of the side surface of the nozzle body 5 toward the fuel injection hole 6 side, the air hole 9 is vertically moved. The air hole 9 was tilted downward in the center direction. Then, by inflowing air from the upper side to the lower side and colliding with the fuel,
The fuel was miniaturized.

In this embodiment, the inclination is 15 °, but it is preferably 0 to 40 °.

Also in the second embodiment as described above, the same effect as in the first embodiment can be obtained.

(Embodiment 3) A method of manufacturing a nozzle and an atomizer, which are an integral structure of the present invention, will be described below.

Table 1 shows the chemical compositions of the comparative material and the material used in the present invention.

[0080]

[Table 1]

As comparative materials, an aluminum material A2017 conventionally used for atomizers and martensitic stainless steels SUS440C and SUS420J2 used for nozzles were manufactured by a conventional method.

Test pieces Nos. 1 to 4 were manufactured by the MIM method.

Metal powders having the chemical components shown in Table 1 and having a particle size of 100 μm or less were thoroughly mixed together with a carbonaceous binder or the like. Then, injection molding was performed by injecting into a molding die.

Then, pre-sintering was performed while applying pressure in vacuum. The mold pressure was about 40 MPa, and the pre-sintering temperature was about 700 ° C. Further, the holding time of the temporary sintering temperature was set to about 30 minutes. Main sintering after temporary sintering is about 110
It was carried out at 0 ° C. for about 30 minutes. Then, the product was processed by machining, quenching and tempering, and machining.

Since the coaxiality between the inner diameter of the mixing chamber 10 and the inner diameter of the engine cylinder side region 19 in the nozzle was manufactured as an integral structure, there was almost no deviation and the standard was sufficiently satisfied.

By applying this MIM method, it is possible to solve the problem of workability and manufacture a nozzle and an atomizer having a complicated shape without compromising the reduction of processing steps and cost reduction which are the advantages of the integrated structure. Became possible.

Next, the results of the corrosion test of the nozzle and the atomizer, which are the integral structure manufactured as described above, are shown in FIG.
And shown in Table 2.

[0088]

[Table 2]

An accelerated corrosion test was performed on the comparative material and the material produced according to the present invention.

The immersion solution is gasoline containing 30% methanol.
Assuming that corrosive components such as deposits and chlorine ions in blowback gas are mixed in the mixed fuel (hereinafter referred to as M30), a solution containing 300 ppm of hydrochloric acid is used as an acceleration condition for 24 hours at 20 ° C. Soaked.

As shown in FIG. 2 and Table 2, the result is A
2017 was significantly corroded with 310 (mg / dm ² day), and SUS440C and SUS420J2 had high corrosivity with 130 and 125 (mg / dm ² day), respectively. On the other hand, the material produced according to the present invention had a lower degree of corrosion and superior corrosion resistance than the above-mentioned conventional materials. That is, by applying the MIM method, the corrosion degree could be made 50 to 100 (mg / dm ² day) while maintaining the workability.

It is expected that the corrosion reaction will change variously in a non-aqueous solution, particularly in an organic solvent such as alcohol fuel due to differences in physicochemical properties, component composition, solution structure, etc. It is considered that the corrosion resistance of the material is good because the formation of the Cr oxide film on the surface and the addition of Mo suppressed the formation of the Cr carbide and reduced the Cr deficient layer.

The addition of Cu further improves the corrosion resistance and hardenability.

From the above results, by applying the MIM method, it is possible to obtain a nozzle and an atomizer which are excellent in workability and corrosion resistance, have high strength, and are made of the same material in an integrated structure.

Further, since the nozzle and the atomizer are made of the same material, they are not different metals, so galvanic corrosion can be prevented and corrosion resistance is improved.

Furthermore, the problem of deviation of coaxiality can be solved,
It was possible to perform accurate injection into the engine cylinder and obtain a low cost and high quality air assist injector.

Further, even if the fuel is highly corrosive / conductive, such as alcohol fuel, the fuel passage and outer surface of the nozzle and atomizer of the one-piece structure will not be corroded, so that the fuel will not be atomized easily. However, it has been found that an air-assisted injector with high reliability can be obtained even when a fuel having high corrosiveness and conductivity such as alcohol fuel is used for a long time.

The present invention is not limited to the above embodiments, and can be modified in any manner without departing from the spirit of the present invention.

[0099]

The following effects can be obtained by using the air assist injector as described above.

(1) By applying the MIM method, it is possible to obtain a nozzle and an atomizer which are excellent in workability and corrosion resistance, have high strength, and have the same material in an integrated structure.

(2) Since the nozzle and the atomizer are made of the same material and do not become dissimilar metals, galvanic corrosion can be prevented and corrosion resistance is improved.

(3) Due to the integrated structure and improved corrosion resistance,
It is possible to obtain an air-assisted injector excellent in safety because the nozzle and atomizer having an integral structure do not fall into the engine cylinder due to corrosion and the engine does not burn.

(4) Due to the integrated structure and the same material, the number of parts can be reduced, and the processing steps of the nozzle and the atomizer can be reduced, especially the joining step can be omitted. Furthermore, because of the integral structure, the problem of deviation of the coaxiality between the nozzle and the atomizer can be solved, and accurate injection can be performed in the engine cylinder. Therefore, the number of processing steps and the deviation of the coaxiality can be reduced, and a low cost and high quality air assist injector can be obtained.

(5) Even for highly corrosive / conductive fuel such as alcohol fuel, the fuel passage and the outer surface of the nozzle and atomizer of the integral structure are not corroded, so that the fuel is not easily atomized. Therefore, it is possible to obtain an air-assisted injector having high reliability even when a fuel having high corrosiveness and conductivity such as alcohol fuel is used for a long period of time.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an air-assisted injector that is an embodiment of the present invention.

FIG. 2 shows the corrosion test results of the present invention and the comparative material.

FIG. 3 shows an integrally structured nozzle and atomizer, which is an embodiment of the present invention.

FIG. 4 is a cross-sectional view of a nozzle and an atomizer having an integral structure, which is an embodiment of the present invention.

FIG. 5 is a vertical sectional view of an air-assisted injector that is an embodiment of the present invention.

FIG. 6 shows a vertical sectional view of a conventional air-assisted injector.

[Explanation of symbols]

1 ... Adjuster, 2 ... Plunger rod, 3 ... Spring, 4 ... Ball valve, 5 ... Nozzle integrated atomizer, 6 ... Fuel injection hole, 7 ... Fuel supply hole, 8 ... Coil, 9 ... Air hole,
10 ... Mixing chamber, 11 ... Nozzle sheet surface, 12 ... Yoke,
13 ... O-ring, 14 ... O-ring, 15 ... O-ring recess, 16 ... Fuel flow, 17 ... Air flow, 18 ... Nozzle mixing chamber area, 19 ... Nozzle engine cylinder side area, 20 ... Single nozzle , 21 ... Single atomizer, 22 ...
Single atomizer air hole, 23 ... Single atomizer air inlet hole.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02M 51/06 F02M 51/06 UR 61/18 360 61/18 360G 69/04 69/04 G (72) Inventor Noboru Baba 7-1, 1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Co., Ltd. Hitachi Research Laboratory (72) Inventor Kazuyoshi Terakado 2520 Takaba, Hitachinaka-shi, Ibaraki Hitachi Co., Ltd. Equipment Division (72) Inventor Kiichi Hoshi 2471 Takashima, Hitachinaka City, Hitachinaka City, Ibaraki 3477 Hitachi Automotive Engineers Ring Co., Ltd. (72) Inventor Toshitaka Uchimura 2520, Takanaka, Hitachinaka City, Ibaraki Co., Ltd. Hitachi Factory Automotive Equipment Division

Claims (12)

[Claims] 1. An electromagnetic valve that vibrates up and down by an electromagnetic suction mechanism, a nozzle that has a fuel injection hole in the center and that opens and closes the fuel injection hole by repeated collisions of the electromagnetic valve, and an engine cylinder from the fuel injection hole. An air assist injector for an internal combustion engine, comprising an atomizer for injecting fuel into the inside, wherein the atomizer and the nozzle have an integral structure and are made of the same material. 2. An air assist injector for an internal combustion engine, comprising: an electromagnetic valve that vibrates up and down by an electromagnetic suction mechanism; and a nozzle that has a fuel injection hole in the center and the electromagnetic valve repeatedly opens and closes to open and close the fuel injection hole. The air-assisted injector according to claim 1, wherein the nozzle is provided with an air hole for supplying air for colliding with the injected fuel. 3. An air assist injector for an internal combustion engine, comprising: an electromagnetic valve that vibrates up and down by an electromagnetic suction mechanism; and a nozzle that has a fuel injection hole in the center and the electromagnetic valve repeatedly opens and closes to open and close the fuel injection hole. In the nozzle, an air hole for supplying air to collide with the injected fuel is provided, the inside of the nozzle has a mixing chamber where the injected fuel and the air collide, and the inside of the nozzle is formed from at least two inner diameters. An air-assisted injector characterized by: 4. An air assist injector for an internal combustion engine, comprising: an electromagnetic valve that vibrates up and down by an electromagnetic suction mechanism; and a nozzle that has a fuel injection hole in the center and the fuel injection hole opens and closes by repeated collisions of the electromagnetic valve. 2. The air-assisted injector according to claim 1, wherein the nozzle is injection-molded and sinter-molded from metal powder and has air holes. 5. An air assist injector for an internal combustion engine, comprising: an electromagnetic valve that vibrates up and down by an electromagnetic suction mechanism; and a nozzle that has a fuel injection hole in the center and the electromagnetic valve repeatedly opens and closes to open and close the injection hole. The atomizer atomizes the fuel internally by colliding the air injected from the air hole with the fuel injected from the injection hole attached to the tip of the nozzle, and injects the fuel into the engine cylinder from the fuel injection hole. An air assist injector for an internal combustion engine, comprising: the atomizer integrated with a nozzle. 6. The air assist injector has three nozzles.
Martensitic stainless steel showing a corrosion degree of 50 to 100 mg / dm ² day when immersed in a solution containing 300 ppm of hydrochloric acid in a mixed fuel consisting of gasoline containing 0% by weight of methanol at room temperature for 24 hours. An air-assisted injector featuring. 7. In the nozzle of the air assist injector,
An air assist injector characterized in that air is ejected in a direction substantially opposite to the direction of ejection of fuel, and the fuel and the air collide with each other. 8. In the nozzle of the air assist injector,
Air assist characterized in that fuel is ejected in a spiral shape, air is ejected from an air hole provided on a side surface of the nozzle in a direction substantially opposite to a direction in which the fuel is ejected, and the fuel and the air are collided with each other. Injector. 9. The air-assisted injector according to claim 1, wherein the nozzle is made of martensitic stainless steel. 10. The air-assisted injector according to claim 9, wherein the martensitic stainless steel is
% By weight, C: 0.2-0.5%, Cr: 12.0-1
An air-assisted injector characterized by 5.0%, inevitable impurities and the balance mainly Fe. 11. The martensitic stainless steel according to claim 10, further comprising Mo: 0.5-1.5 by weight%.
%, An air-assisted injector. 12. The martensitic stainless steel according to claim 11, further comprising Cu: 0.1 to 1.0 by weight%.
%, An air-assisted injector.