JPH0712668Y2 - Spark ignition direct injection engine - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a spark ignition direct injection engine (hereinafter referred to as a spark ignition direct injection engine), and in particular, forms a stable rich mixture zone near the spark plug. The structure for doing.

[Conventional technology]

In a spark ignition direct injection engine, Japanese Utility Model Laid-Open No. 55-97129 discloses a structure in which spray is guided along a wall surface of a combustion chamber to a spark plug and directly applied to the spark plug. In this case, the spark plug is off the center of the swirl.

Japanese Utility Model Laid-Open No. 56-65217 discloses a structure in which most of the spray is directed to the spark plug while being placed on the swirl along the wall surface of the piston recess and directed to the spark plug.

U.S. Pat. No. 3,195,520 shows a structure in which the spray is once applied to a convex portion formed on the piston side and the reflection is directly applied to the spark plug.

Although No. 57-43323 is not a direct injection engine, it shows a combustion chamber in which a warped portion for preventing fuel dripping is formed on the lower surface of the cylinder head near the spark plug.

Japanese Utility Model Laid-Open No. 62-87169, Japanese Patent Laid-Open No. 61-167116, and Japanese Utility Model Laid-Open No. 62-87127 show a structure in which spray from one of the multiple injection holes is directly applied to the ignition plug.

Japanese Utility Model Laid-Open No. Sho 62-90980 discloses a fuel injection valve in which the injection holes of the multiple injection holes toward the spark plug side are larger than the other injection holes.

These prior arts are classified into any of the following three, when sorted out.

(A) Those that directly ignite the spray injected from the injection valve ...
JP 62-87169, JP 61-167116, JP 62-8712
No. 7, Jitsukai Sho 62-90980, (In addition, there are JP-A-62-168951 and JP-A-62-139924.) (B) Ignition of collision atomization spray produced when hitting a collision wall What to do ... USP 3195520, (Other Japanese Patent Application Laid-Open No. 62-139921
There are also issues. (C) A fuel liquid film is formed on the wall surface and the vaporized vapor is ignited ... Jitsukai Sho 56-65217 (in addition, JP-A-54-89111, JP-A-57-11341, and JP-A-59) (There is also No. 192823.) (Problems to be solved by the invention) However, each of the conventional techniques classified into the above three has the following problems.

For those classified as (a) above, the formation position of the spray is likely to change due to the penetration force of the spray and the air flow, and ignition instability and plug smoldering are likely to occur.

For those classified into (b) above, atomization deteriorates when the injection amount is reduced, and ignition instability and plug smoldering occur.

For those classified into (c) above, it is necessary to set the air flow for moving the fuel vapor, and it is not suitable for engines with many restrictions on the fuel chamber structure, such as 4-valve engine. .

In order to solve the above problems, the present invention provides a spark ignition direct injection engine capable of steadily forming a stable air-fuel mixture in the vicinity of a spark plug without causing a problem such as spark plug smoldering. To aim.

[Means for achieving the task]

The above problems can be achieved by the spark ignition in-cylinder direct injection engine described in (1) below.

(1) A spark plug facing the combustion chamber; fuel is directly injected into the combustion chamber, and at least one of the injection holes is directed toward the spark plug so that the spray injected from the injection hole hits the cylinder head surface. A fuel injection valve; provided on the ignition plug side of the portion of the lower surface of the cylinder head where the spray hits, and between the fuel injection valve and the ignition plug near the ignition plug side, and extending the ignition plug And a projecting portion projecting toward the combustion chamber, the projecting portion having a wall surface inclined so as to pass below the spark ignition direct injection engine.

The spark ignition direct injection engine of the above (1) can take the following modes.

(2) A combustion chamber defined by a cylinder bore wall surface, a cylinder head lower surface, and a piston upper surface; an ignition plug attached to the cylinder head so as to face the combustion chamber; and an ignition plug arranged so as to face the combustion chamber. There is a plurality of injection holes, and at least one injection hole of the plurality of injection holes directs fuel toward the lower surface of the cylinder head and toward the spark plug so that the spray injected from the injection holes hits the cylinder head surface. A fuel injection valve, the injection direction of which is directed so as to inject; and a portion of the lower surface of the cylinder head that is closer to the spark plug than a portion where the spray hits, and between the spark plug and the fuel injection valve, and A flow control wall surface for controlling the flow direction of the spray, which is formed at a portion close to the spark plug and whose extension is inclined so as to pass under the spark plug;
A spark ignition direct injection engine, comprising: a protrusion protruding toward the fuel chamber.

(3) The protruding portion has an edge portion at the end of the flow control wall surface on the downstream side in the spray flow direction, for separating the spray flowing along the flow control wall surface from the flow control wall surface (2) Spark ignition direct injection engine described.

(4) The spark ignition direct injection engine according to (2), wherein the flow control wall surface is connected to the lower surface of the cylinder head via a smoothly curved curved surface on the upstream side in the spray flow direction.

(5) Of the plurality of injection holes of the fuel injection valve, at least one injection hole for injecting fuel toward the lower surface of the cylinder head injects fuel toward the lower surface of the cylinder head at a shallow angle (2). Spark ignition direct injection engine described.

(6) Of the plurality of injection holes of the fuel injection valve, the diameter of the injection hole for injecting fuel toward the lower surface of the cylinder head is larger than the diameter of the other injection holes. Ignition direct injection engine.

(7) Among the plurality of injection holes of the fuel injection valve, the injection holes other than the injection holes for injecting fuel toward the lower surface of the cylinder head have the injection direction directed to the piston top surface. Spark ignition direct injection engine.

(8) The spark plug is located in a central portion of the combustion chamber, and the fuel injection valve is arranged on an outer peripheral portion of the combustion chamber (2)
Spark ignition direct injection engine described.

(9) The spark ignition direct injection engine according to (2), wherein the spark plug is located at a position deviated from a central portion of the combustion chamber.

[Action]

Of the sprays injected from the plurality of injection holes, the spray directed toward the lower surface of the cylinder head flows toward the spark plug along the lower surface of the cylinder head when reaching the lower surface of the cylinder head, and reaches the protrusion between the spark plug and the fuel injection valve. The direction of the center of the flow can be changed along the inclined wall surface of the protruding portion so as to be directed toward the lower portion of the spark plug. The spray flowing below the spark plug spreads there, and a stable rich mixture zone in the boundary region can be formed near the spark plug regardless of the presence or absence of air flow, and the ignitability is improved. Further, since the spray cannot be directly sprayed on the spark plug gap, smoldering of the spark plug does not occur. Such a stable rich mixture zone cannot be formed by a conventional one. This is because if the jet is strongly blown toward the spark plug, it will fly to the outer peripheral portion by the force of inertia, and if it is jetted weakly so as to stay near the spark plug, the boundary becomes unstable.

Of the multiple injection holes, those that are not injected toward the lower surface of the cylinder head form a columnar shape and fly to the outer peripheral part of the swirl with a strong penetration force and disperse along the strong flow of the outer peripheral part of the swirl. , Spreads to the complete combustion range, good combustibility is obtained, and the output is improved.

〔Example〕

Hereinafter, preferred embodiments of a spark ignition direct injection engine according to the present invention will be described with reference to the drawings.

First, a common configuration of a plurality of embodiments will be described.

1, 3, and 4, the combustion chamber 14 includes a lower surface 16 of a cylinder head 15, a cylinder bore wall surface 1, and a piston 2.
Surrounded by the upper surface 17 of the. Spark plug 4 in combustion chamber 14
The fuel injection valve 5 faces the fuel injection valve 5, and the fuel injection valve 5 directly injects fuel into the cylinder, thus forming a spark ignition direct injection engine.

The fuel injection valve 5 has a plurality of injection holes at its tip, and at least one of them has its injection direction directed toward the lower surface 16 of the cylinder head, and the other injection holes are directed toward the piston top surface 17 or the combustion chamber. It is directed. In the figure, 18a shows the spray from the injection hole directed to the lower surface of the cylinder head, and 18b and 18c show the spray from the remaining injection holes.

Within the combustion chamber 14, a portion of the lower surface 16 of the cylinder head, which is closer to the spark plug 4 than the spray 18a is, and between the spark plug 4 and the fuel injection valve 5 and close to the spark plug 4. A protruding portion 19 that protrudes toward the front is formed. The protrusion 19 has a wall surface 11 (hereinafter, referred to as a flow control wall surface) for controlling the flow direction of the spray 18a, and the extension of the flow control wall surface 11 passes below the spark plug 4. The inclination is set in. In this way, the inclination is specified by the spray 18a.
This is to prevent the center line C of the above from facing the spark plug gap portion 20.

The protruding portion 19 has an edge portion 12 at the end of the flow control wall surface 11 on the downstream side in the flow direction of the spray 18a, which is angled so as to separate the spray flowing along the flow control wall surface 11 from the flow control wall surface 11. Have. The edge portion 12 is provided in this manner so that the center line C of the spray 18a does not adhere to the wall surface due to the Coanda effect and flow toward the spark plug gap portion 20.

The flow control wall surface 11 is smoothly connected to the wall surface 3 of the lower surface 16 of the cylinder head, which is on the upstream side in the flow direction of the spray 18a, and which is sprayed with the spray 18a and flows along the curved surface 13. The reason why the surfaces 3, 13, 11 are connected smoothly is that the surface 11 works to change the direction of the flow of the spray 18a and is not a surface for colliding the spray 18a and atomizing it.

Of the spray from the fuel injection valve 5, the cylinder head lower surface 16
18a toward the wall surface 3 of the spray is sprayed so as to contact the wall surface 3 at a shallow angle (the smaller the angle is about 30 ° or less, the better).
The angle of the nozzle hole corresponding to 18a is defined. The reason why the angle is shallow is that the fuel is extremely atomized and does not scatter when it hits the wall surface 3, and most of the spray 18a is efficiently guided to the vicinity of the spark plug 4.

Next, different configurations of the respective embodiments will be described.

1 and 2 show a first embodiment of the present invention. In the first embodiment, the spark plug 4 is located in the center of the combustion chamber 14,
The lower end portion including the spark plug gap portion 20 projects into the combustion chamber 14. Further, the fuel injection valve 5 is provided on the outer peripheral portion of the combustion chamber 14. The central disposition of the spark plug 4 minimizes the flame propagation distance to improve the combustibility, and facilitates the space connection with the port 6, the valve 7, the stem 8, the water jacket, and the like. Further, in the central disposition of the spark plug 4, when the port 6 includes a swirl port for intake air, an intake swirl is formed in the combustion chamber 14, but since the swirl has a strong flow near the outer periphery and a weak center, the vicinity of the spark plug 4 is considered. It also contributes to not disturbing the rich mixture zone 21 formed in the.

Since the fuel injection valve 5 provided so as to face the outer peripheral portion of the combustion chamber 14 can have a relatively small diameter structure as compared with the spark plug 4, it is relatively difficult even if it is provided at the outer peripheral portion through which the port passes. It can be arranged without touching. A notch 10 is formed in the piston 2 to prevent interference with the fuel injection valve 5. 9
Is a gasket.

FIG. 2 shows the flow distribution when the spray 18a is separated from the edge portion 12 of the protruding portion 19 over time. As can be seen from FIG. 2, the boundary region B on the spark plug 4 side of the rich mixture zone A formed corresponding to the distribution of the spray 18a is on a substantially constant line regardless of the passage of time, and this position is On the upper side of the center line C, it is not only substantially constant regardless of the time elapsed after injection, but is also substantially independent of the presence or absence of swirl and the magnitude of the fuel injection amount. That is, it is possible to form a very stable boundary region B of the rich air-fuel mixture zone A. The purpose of providing the protruding portion 19 is to form the stable boundary area B, and the spark plug gap portion 20 is arranged in the boundary area B. The reason why the spark plug gap portion 20 is provided in the boundary area B is that the timing of injection and ignition can be set relatively freely, and stable and favorable ignition that is not affected by other factors can be obtained.

FIG. 3 shows a second embodiment of the present invention. The second embodiment is different from the first embodiment in that the nozzle hole for ejecting the spray 18a injected toward the wall surface 3 of the cylinder head lower surface 16 has a larger diameter than the other nozzle holes. The configuration is similar to that of the first embodiment. The reason for using a large diameter is to supply a sufficient amount of fuel near the spark plug 4.

FIG. 4 shows a third embodiment of the present invention. In the third embodiment, the spark plug 4 is provided at a position off the center of the combustion chamber 14. With this arrangement, the swirl of the spark plug portion becomes stronger than in the first and second embodiments, but as described with reference to FIG. 2, the boundary area B is very stable, so some swirl may occur. Even if it is present, stable ignition performance is obtained without being greatly affected by it. In the third embodiment, port 21,
22 is open to the cylinder bore. Other configurations are similar to those of the first and second embodiments.

Next, the operation common to each embodiment will be described.

By forming the protruding portion 19 on the lower surface 16 of the cylinder head, the spray 18a flowing along the wall surface 3 of the lower surface of the cylinder head is directed toward the downward direction of the spark plug 4 by the flow control wall surface 11 of the protruding portion 19. Is changed so as to face toward the lower portion of the spark plug 4 away from the protruding portion 19 by the edge portion 12 to form a rich mixture zone A in the vicinity of the spark plug,
The boundary region B of the rich mixture zone A on the side close to the spark plug 4 is formed in a substantially constant region insensitive to the elapsed time from the injection start timing, and the spark plug gap portion 20 is located in this boundary region B. As a result, stable ignition can always be obtained regardless of changes in the injection timing and regardless of the presence or absence of air flow. In this case, since the spark plug gap 20 is not directly sprayed, spark plug smolder does not occur.

Sprays 18b, 18c, (18
d) is columnar and has a strong penetration force, and flies to the outer periphery of the combustion chamber 14, where it is dispersed in the combustion chamber 14 along a swirl that is stronger toward the outer periphery, atomizes, and good combustion and output are obtained. can get.

Next, the operation peculiar to each embodiment will be described.

In the first and second embodiments, the central arrangement of the spark plug 4 with respect to the combustion chamber 14 makes it difficult to reduce the diameter of the spark plug 4.
Can be arranged without difficulty by utilizing the part which was a conventional dead space surrounded by the port 6, and facilitates the space arrangement. Further, the central arrangement of the spark plugs 4 minimizes the flame propagation distance, which helps to obtain good flammability. Further, the piston top surface 17 has a wall that rises almost upward on the outer circumference, and the spray 18 injected onto the piston top surface 17
It is possible to prevent b and 18c from flowing to the wall surface of the cylinder bore.

In the case where the diameter of the injection hole for injecting the spray 18a toward the wall surface 3 on the lower surface of the cylinder head is large as in the second embodiment, a denser mixture zone A is formed in the vicinity of the spark plug 4. Be useful.

When the spark plug 4 is located outside the center of the combustion chamber 14 as in the third embodiment, the swirl can be made to work in the vicinity of the spark plug 4 as well. Arrangement is also possible.

[Effect of device]

According to the present invention, since the protruding portion 19 is provided between the spark plug 4 and the combustion injection valve 5, the spray 18a from at least one of the plurality of injection holes is directed toward the lower side of the spark plug 4. It is possible to form a rich mixture zone A having a stable boundary area B in the vicinity, which is good, is insensitive to changes in ignition timing and injection timing, and is not significantly affected by the presence or absence of air flow, and stable ignitability. Can be obtained. Also spray
Since 18a cannot be sprayed directly on the spark plug gap portion 20, spark plug smolder does not occur.

[Brief description of drawings]

1 is a sectional view of a main part of a spark ignition direct injection engine according to a first embodiment of the present invention, and FIG. 2 is a partially enlarged sectional view showing a formation state of a rich mixture zone in the vicinity of a protrusion in FIG. 1, FIG. 3 is a sectional view of an essential part of a spark ignition direct injection engine according to a second embodiment of the present invention, and FIG. 4 is a sectional view of an essential part of a spark ignition direct injection engine according to a third embodiment of the present invention. . 4 …… Ignition plug 5 …… Fuel injection valve 11 …… Flow control wall 12 …… Edge 13 …… Curved surface 16 …… Cylinder head bottom surface 18a, 18b, 18c …… Spray 19 …… Projection A …… Dense mixing Qi Zone B ... (Stable) boundary area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiyuki Tamaki 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor, Masaaki Koyasu 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A spark plug facing a combustion chamber; fuel is directly injected into the combustion chamber, and at least one of the injection holes is directed toward the spark plug so that the spray injected from the injection hole hits a cylinder head surface. A fuel injection valve provided on the ignition plug side of a portion of the lower surface of the cylinder head on which the spray hits, and between the fuel injection valve and the ignition plug near the ignition plug side. A spark ignition direct injection engine, comprising: a protrusion having a wall surface inclined so as to pass below the spark plug and protruding toward the combustion chamber.