JP2002332934A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve which starts an engine early at a low load of the engine and realizes high output at a high load of the engine. SOLUTION: In a fuel injection valve of an internal combustion engine provided with a valve body in which a fuel injection passage group constituted by a first fuel injection passage and a second fuel injection passage is arranged, a valve element slidably arranged in the valve body and a fuel passage formed between the valve body and the valve element, a fuel is respectively injected from the first fuel injection passage and the second fuel injection passage at a low load of the engine, while the fuel is merged and injected from the first fuel injection passage and the second fuel injection passage at a high load of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection valve for an internal combustion engine.

[0002]

2. Description of the Related Art In the operation of a direct injection type internal combustion engine, when the engine is under a low load, it is necessary to atomize the fuel so as to burn the fuel early after the injection in order to start the engine early. Also, when the engine is under a high load, in order to achieve high output, a relatively large amount of air in the combustion chamber is used to burn a large amount of fuel, and the fuel is given a strong penetration force so that the fuel is discharged. It is desirable to inject.

[0003] In order to satisfy such demands, for example, Japanese Patent Application Laid-Open No. Hei 7-167016 discloses a fuel injection valve having a large number of fine injection holes. In the operation of an internal combustion engine using this fuel injection valve, the size of the injection hole is small, so that the fuel can be finely injected at a low engine load, and the fuel has a strong penetration force at a high engine load. The fuel is injected at high pressure.

[0004]

However, the smaller the particle size of the injected fuel is, the smaller the penetration force is. Therefore, even if the fuel is injected at a high pressure, there is a limit in improving the penetration force of the fuel. There has been a problem that the output cannot sometimes be sufficiently increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection valve which starts the engine early when the engine is under a low load and realizes a high output when the engine is under a high load.

[0006]

According to a first aspect of the present invention, there is provided a fuel injection valve in which a fuel injection passage group including a first fuel injection passage and a second fuel injection passage is disposed. And a valve body slidably disposed in the valve body, and a fuel injection valve for an internal combustion engine including a fuel passage formed between the valve body and the valve body. The fuel is injected from the injection passage and the second fuel injection passage independently of each other, and the fuel is injected from the first fuel injection passage and the second fuel injection passage so as to be merged at a high engine load.

According to a second aspect of the present invention, there is provided a fuel injection valve according to the first aspect, wherein the second fuel injection passage is located downstream of the first fuel injection passage with respect to the fuel passage. The second fuel injection passage is arranged and cavitation is generated on the side of the first fuel injection passage near the entrance of the second fuel injection passage when the engine is heavily loaded.

According to a third aspect of the present invention, there is provided a fuel injection valve according to the second aspect, wherein the first fuel injection passage narrows from an inlet to an outlet of the first fuel injection passage. And the second fuel injection passage has a tapered shape that widens from the inlet to the outlet of the second fuel injection passage.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic longitudinal sectional view of a cylinder of an internal combustion engine provided with a fuel injection valve of the present invention,
Reference numeral 1 denotes a fuel injection valve for directly injecting fuel from the upper part of the cylinder, reference numeral 2 denotes a piston, and reference numeral 3 denotes a concave combustion chamber formed on the upper surface of the piston 2, respectively. The fuel injection valve 1 is disposed substantially vertically above the center of the combustion chamber 3. The fuel injection valve 1 mainly includes a valve body 5 and a valve body 4.
The fuel injection valve 1 is an internal valve that injects fuel when the valve body 5 is lifted in the axial direction of the fuel injection valve 1.

First, the fuel injection valve 1 will be described. FIG. 2 is a partial sectional view of the fuel injection valve of the present invention. 4 is a valve body having a substantially conical inner surface, 5 is a valve body having a substantially conical outer surface, 6 is a first fuel injection passage having a small cross section provided in the valve body 4, and 7 is a first fuel injection passage. A second fuel injection passage having a small cross section provided downstream of the fuel passage 8 than the fuel passage 6, a fuel passage 8 formed between a substantially conical inner surface of the valve body 4 and a substantially conical outer surface of the valve body 5. Reference numerals 9 denote seat portions on which the valve body 5 provided on the valve body 4 upstream of the first fuel injection passage 6 sits. In the fuel injection valve 1, a plurality of fuel injection passage groups including a first fuel injection passage 6 and a second fuel injection passage 7 are arranged at substantially equal intervals in the circumferential direction of the valve 1. The valve body 5 of the fuel injection valve 1 has a valve closing position in which the valve body 5 is seated on the seat portion 9 of the valve body 4 and shuts off a pressure accumulating chamber (not shown) and the fuel passage 8 so that fuel is not injected. The valve element 5 is separated from the seat portion 9 of the valve body 4 to connect the accumulator with the fuel passage 8 to inject fuel from the first fuel injection passage 6 or the second fuel injection passage 7 to a valve-open position. The fuel injection valve 1 is slidable up and down in the longitudinal axis direction with respect to the valve body 4. By controlling the movement of the valve body 5, fuel injection is controlled.

Incidentally, it is required that the operation of the internal combustion engine be started early when the engine is under a low load, and to realize a high output when the engine is under a high load. That is, it is preferable to inject fine-grained fuel from the fuel injection valve when the engine is under a low load, and to strongly inject the fuel when the engine is under a high load in order to burn a large amount of fuel by using a lot of air in the combustion chamber. For this reason, the conventional fuel injection valve is formed with a small fuel injection passage having a cross section appropriately separated from each other. By injecting the fuel with such a fuel injection valve, at the time of low engine load, fine fuel spray can be appropriately separated from other fuel spray and distributed, and fuel can be injected early. However, when the engine is under a high load, there is a problem that even if the fuel is injected at a high pressure, the fuel cannot be injected sufficiently far because the fine-grained fuel has a small penetration force. In order to solve such a problem, according to the present invention, the first fuel injection passage 6 at the time of high engine load is provided by the method described below.
And the fuel spray is merged from the second fuel injection passage 7 and injected far away.

Next, the first fuel injection passage 6 will be described. FIG. 2 is a partial cross-sectional view of the fuel injection valve according to the first embodiment of the present invention when the engine is under a low load. FIG. 3 is a partial cross-sectional view of the fuel injection valve according to the first embodiment of the present invention when the engine is under a high load. FIG. As shown in FIGS. 2 and 3, a substantially cylindrical first fuel injection passage 6 extends at an angle with respect to the fuel passage 8 in the valve body 4. The corner of the inlet 6a of the first fuel injection passage 6 is rounded, for example, with a radius of curvature of about 0.1 mm, and fuel flowing from the fuel passage 8 into the first fuel injection passage 6 flows along the inlet 6a. Irrespective of the flow velocity of the fuel, the flow of the fuel is adjusted in the axial direction of the first fuel injection passage 6, and the fuel is injected from the outlet 6b substantially in the axial direction of the first fuel injection passage 6. You.

Next, the second fuel injection passage 7 will be described. As shown in FIGS. 2 and 3, a substantially cylindrical second fuel injection passage 7 is provided downstream of the first fuel injection passage 6 in the valve body 4, and the fuel is substantially parallel to the first fuel injection passage 6. It extends obliquely with respect to the passage 8. The corner of the inlet 7a of the second fuel injection passage 7 is hardly rounded,
At the inlet 7a, the fuel flow path changes rapidly. Therefore, the fuel passing through the inlet 7a flows in relatively smoothly when the engine flow is low and the fuel flow rate is low, but when the engine flow is high and the fuel flow rate is high, the fuel flow having the velocity component in the direction of the fuel passage 8 is provided. Is separated near the inlet 7a of the second fuel injection passage 7, that is, cavitation of gas occurs in a region near the first fuel injection passage 6 and flows only from a region far from the first fuel injection passage 6. The fuel that has flowed into the second fuel injection passage 7 advances while widening its distribution area toward the first fuel injection passage 6, that is, the fuel advances toward the first fuel injection passage 6. Therefore, at the time of high engine load, the spray injected from the second fuel injection passage 7 merges with the spray injected substantially simultaneously from the first fuel injection passage 6, and the penetration is larger than the penetration force of the spray injected alone. A powerful spray is formed. As described above, when the engine is at a low load where it is desired not to be too close to the spray injected from the first fuel injection passage 6, the fuel is injected from the second fuel injection passage 7 substantially in the axial direction of the second fuel injection passage 7, At a high engine load where it is desired to merge with the spray injected from the first fuel injection passage 6, the fuel can be injected from the second fuel injection passage 7 with a velocity component directed toward the first fuel injection passage 6.

The distance between the first fuel injection passage 6 and the second fuel injection passage 7, the cross-sectional dimensions of each fuel injection passage 6, 7 and the length and direction of the passages 6, 7 described above are determined by the low engine load. At this time, the sprays injected from the first fuel injection passage 6 and the second fuel injection passage 7 are not too close to each other, and the spray injected from the second fuel injection passage 7 at the time of high engine load merges with the first fuel injection passage 6 It is determined to satisfy the condition that it is possible to

Next, the operation of the fuel injection valve of the present invention when the engine load is low will be described. At the time of low engine load, as shown in FIG. 2, the fuel that has been held at a relatively small pressure in the accumulator to burn a relatively small amount of fuel flows along the fuel passage 8 at a relatively small flow velocity. (Shown by F1). The fuel passing through the vicinity of the inlet 6a of the first fuel injection passage 6 is guided by the corner of the inlet 6a, smoothly flows into the first fuel injection passage 6 (F2), and proceeds in the first fuel injection passage 6. Is adjusted in the axial direction of the first fuel injection passage 6 (F3), and is injected from the outlet 6b in the axial direction of the first fuel injection passage 6. On the other hand, the fuel that does not enter the first fuel injection passage 6 flows further downstream along the fuel passage 8 (F
4), flows into the second fuel injection passage 7 from the inlet 7a (F
5). The flow of the fuel traveling through the second fuel injection passage 7 is adjusted in the axial direction of the second fuel injection passage 7 (F6), and the outlet 7
b, the fuel is injected in the axial direction of the second fuel injection passage 7. That is, the fuel injected from each of the first fuel injection passage 6 and the second fuel injection passage 7 advances in the axial direction of each of the fuel injection passages 6 and 7, and the fuel spray injected from the other fuel injection passages It can be separated appropriately. Thus,
At the time of low engine load, fine-granular fuel can be burned at an early stage, and early startability of the engine can be realized.

Next, the operation of the fuel injection valve of the present invention at the time of high engine load will be described. At the time of high engine load, as shown in FIG. 3, the fuel which has been held at a relatively high pressure in the accumulator to burn a relatively large amount of fuel flows along the fuel passage 8 at a relatively high flow rate. (Indicated by F1 ′). The fuel that passes through the vicinity of the inlet 6a of the first fuel injection passage 6 smoothly flows into the first fuel injection passage 6 guided by the corner of the inlet 6a (F2 '), and proceeds in the first fuel injection passage 6. The flow of the fuel is adjusted in the axial direction of the first fuel injection passage 6 (F3 '), and the fuel is injected from the outlet 6b at a relatively large flow velocity in the axial direction of the first fuel injection passage 6. On the other hand, the fuel that does not enter the first fuel injection passage 6 is
(F4 '), the inlet 7 of the second fuel injection passage 7
a (F5 '). The fuel flow having a relatively high flow velocity separates near the rapidly changing inlet 7a. That is, cavitation 10 occurs on the first fuel injection passage 6 side near the inlet 7a of the second fuel injection passage 7, and
The fuel that flows in only from the region near the first fuel injection passage 6 near the “a” travels while expanding the distribution region toward the first fuel injection passage 6, so that the first fuel flows from the outlet 7 b of the second fuel injection passage 6. Injection is performed at a relatively high flow velocity toward the injection passage 6 (F6 ').

As shown in FIG. 3, the spray injected from the second fuel injection passage 7 in the direction inclined toward the first fuel injection passage 6 with respect to the axial direction of the second fuel injection passage 7 as shown in FIG. It moves and merges with the spray injected from the first fuel injection passage 6 at the position indicated by 11. In this way, when the two sprays merge, the suction action acts on the two sprays, so that the sprays are not diffused at the time of merger, but the flow directions of the two different sprays are adjusted in one direction to form one large spray. grow up. This large spray has an increased penetration force, and is sprayed farther. By injecting fuel in this manner, a large amount of fuel can be burned using a relatively large amount of air in the combustion chamber, so that a high output can be realized at a high engine load. As described above, using the fuel injection valve of the present invention, it is possible to realize early startability at a low engine load and high output at a high engine load.

Next, a second embodiment will be described. FIG. 4 is a partial cross-sectional view of the fuel injection valve of the second embodiment of the present invention at the time of low engine load, and FIG. 5 is a partial cross-sectional view of the fuel injection valve of the second embodiment of the present invention at the time of high engine load. is there. As shown in FIG. 4, in the present embodiment, the first fuel injection passage 6 has a tapered shape narrowing from the inlet 6a toward the outlet 6b. The tapered inclination is preferably, for example, about 3 to 5 degrees with respect to the longitudinal axis of the first fuel injection passage 6. Since the change in the flow path from the fuel passage 8 to the first fuel injection passage 6 is gentle, the fuel can flow more smoothly when flowing from the fuel passage 8 into the first fuel injection passage 6. It becomes possible (F2 ";F2"). As a result, the flow of the fuel flowing in the first fuel injection passage 6 is more appropriately adjusted (F3 ''; F3 ''''), and the fuel is injected with a large penetration force. As described above, the fuel in the first fuel injection passage 6 is rectified more favorably, so that when the engine is under low load, the fuel is injected faster and the fuel burns more quickly, so that the early startability is improved and the engine high load is improved. At times, the fuel can be injected farther and utilize more air to burn the fuel, further increasing output.

As shown in FIG. 4, in the present embodiment, the second fuel injection passage 7 has a tapered shape that widens from the inlet 7a to the outlet 7b. This tapered inclination is, for example, about 3 to 5 ° with respect to the longitudinal axis of the second fuel injection passage 7.
Is preferred. As described above, the flow path from the fuel passage 8 to the second fuel injection passage 7 changes abruptly, and when the flow rate of the fuel is low and the engine is under a low load, the fuel flows in relatively smoothly, and almost the second fuel injection passage 7 Is injected in the axial direction of (F)
4 ″ to F6 ″), when the fuel flow rate is high and the engine is under a high load, near the inlet 7a of the second fuel injection passage 7, the cavitation 1 larger than the first embodiment is provided on the first fuel injection passage 6 side.
2 occurs. Therefore, the fuel traveling in the second fuel injection passage 7 is injected from the outlet 7b with a large velocity component in the direction of the first fuel injection passage 6 so that the second fuel injection passage 7 It merges at a position 13 closer to the valve body 4 than in one embodiment, and the combined spray has a greater penetration force (F4 '''' to F6 '''').

Next, a third embodiment of the present invention will be described. In the first and second embodiments described above, fuel is injected from both the first fuel injection passage 6 and the second fuel injection passage 7 when the engine is under low load. It is configured to inject fuel only from the first fuel injection passage 6. FIG. 6 is a view showing a fuel injection valve according to a third embodiment of the present invention. As shown in FIG. 6, the valve element 5 includes a valve element body 5a, a conical valve element inclined part 5b formed below the valve element body 5a, and a valve element inclined part having a columnar part. It mainly comprises a valve body guide portion 5c formed on the lower side of 5b. On the inner surface of the valve body 4, there is formed a valve body inclined part 4a which is inclined at substantially the same inclination as that of the valve body inclined part 5b so that the valve body inclined part 5b is seated. On the lower side, a fuel reservoir 4b having an inner surface substantially the same size as the outer diameter of the cylindrical portion of the valve body guide is formed so as to house the valve body guide 5c. A first fuel injection passage 6 having a small cross section extends from the valve body inclined portion 4a to the outer surface of the valve body 4 and is inclined on the same plane as the first fuel injection passage 6 toward the first fuel injection passage 6 side. Passage 7
Extends from the fuel reservoir 4b to the outer surface of the valve body 4. With such a configuration, when fuel is simultaneously injected from the first fuel injection passage 6 and the second fuel injection passage 7, the spray injected from the first fuel injection passage 6 and the spray injected from the second fuel injection passage 7 Are merged to form a large spray, which is ejected far away. A seat portion on which the valve body inclined portion 5b is seated is formed above the first fuel injection passage 6 in the valve body inclined portion 4a.

With the above configuration, when the valve is closed, the valve body 5 is seated on the seat portion of the valve body 4 to block the first fuel injection passage 6 and the second fuel injection passage 7 from the fuel passage 8. . When the engine is under a low load, the valve body 5 is lifted to such an extent that the valve body guide portion 5c is held in the fuel reservoir 4b, and only the first fuel injection passage 6 communicates with the fuel passage 8 so that the first fuel Fine fuel is injected only from the injection passage 6.
Thus, when the engine is under a low load, the finely divided fuel can be burned at an early stage, and the engine can be started at an early stage. Also, at the time of high engine load, the valve body guide portion 5
The valve body 5 is lifted to such an extent that c is separated from the fuel reservoir 4b, and fuel is injected from both the first fuel injection passage 6 and the second fuel injection passage 7 at a relatively high pressure.
And the spray injected from the second fuel injection passage 7 are merged to form a large spray and to be injected far away. Thus, when the engine is under a high load, a relatively large amount of fuel can be burned by using a relatively large amount of fuel in the combustion chamber, and a high output can be realized.

[0022]

The fuel injection valve of the internal combustion engine according to the present invention
A valve body in which a fuel injection passage group composed of a first fuel injection passage and a second fuel injection passage is arranged, a valve body slidably arranged in the valve body, a valve body and a valve body; A fuel passage formed between the first fuel injection passage and the second fuel injection passage when the engine is under a low load; Fuel is injected from the fuel injection passage and the second fuel injection passage so as to merge. Thereby, at the time of low engine load, fine fuel is injected from the first fuel injection passage and the second fuel injection passage without approaching each other, and the fine fuel is distributed over a relatively wide range, so that the fuel is distributed. The fuel injected from the first fuel injection passage and the fuel injected from the second fuel injection passage are joined together at a high engine load. , Combustion using a large amount of air in the combustion chamber, that is, high output can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of the inside of a cylinder of an internal combustion engine provided with a fuel injection valve of the present invention.

FIG. 2 is a partial cross-sectional view of the fuel injection valve of the first embodiment of the present invention when the engine is under a low load.

FIG. 3 is a partial cross-sectional view of the fuel injection valve according to the first embodiment of the present invention when the engine is under a high load.

FIG. 4 is a partial sectional view of a fuel injection valve according to a second embodiment of the present invention when the engine is under a low load.

FIG. 5 is a partial sectional view of a fuel injection valve according to a second embodiment of the present invention when the engine is under a high load.

FIG. 6 is a schematic longitudinal sectional view of a fuel injection valve according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve 4 ... Valve body 5 ... Valve body 6 ... First fuel injection passage 7 ... Second fuel injection passage 8 ... Fuel passage

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryo Hasegawa 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Hisashi Oki 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation ( 72) Inventor Hiromichi Yanagihara 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Taiichi Mori 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Hide Itabashi Aichi Toyota Motor Co., Ltd. 1 Toyota Town, Toyota Prefecture (72) Inventor Masanori Koie 2-1-1 Toyota-machi, Kariya City, Aichi Prefecture F-term in Toyota Industries Corporation 3G066 AA07 AB02 AD12 BA04 BA14 BA16 CC06T CC14 CC21 CC26 CC48 CE13 DB08 DB09

Claims (3)

[Claims] 1. A valve body in which a fuel injection passage group composed of a first fuel injection passage and a second fuel injection passage is arranged; a valve body slidably arranged in the valve body; A fuel injection valve for an internal combustion engine having a fuel passage formed between the valve body and the valve body, wherein fuel is independent from the first fuel injection passage and the second fuel injection passage at a low engine load. A fuel injection valve for injecting fuel from the first fuel injection passage and the second fuel injection passage at a high engine load. 2. The second fuel injection passage is disposed downstream of the first fuel injection passage with respect to the first fuel injection passage, and the first fuel injection passage is located near an inlet of the second fuel injection passage when an engine is heavily loaded. The fuel injection valve according to claim 1, wherein cavitation is generated on an injection passage side. 3. The first fuel injection passage has a tapered shape narrowing from an inlet to the outlet of the first fuel injection passage, and the second fuel injection passage is formed from an inlet of the second fuel injection passage. 3. The fuel injection valve according to claim 2, wherein the fuel injection valve has a tapered shape that widens toward an outlet.