JPH06173687A - Combustion chamber having subchamber of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the fuel consumption of an engine and its reliability by providing a subchamber with a small diameter part formed on the side of an injection port and a large diameter part adjacent to the small diameter part, and providing a throttle part between the small diameter part and the large diameter part so as to make them communicate with each other. CONSTITUTION:A main combustion chamber 19 is formed of a cylinder 12, a piston 13 and a cylinder head 16. A subchamber is cylindrical and has a lower small diameter part 33 and an upper large diameter part 34. A throttle part 35 being smaller in a sectional area than the small diameter part 33 is formed between the small diameter part 33 and the large diameter part 34 to make the small diameter part 33 communicate with the large diameter part 34. The subchamber 3 and the main combustion chamber 19 communicate mutually through a plurality of injection ports 36. When compressed air flows into the subchamber 32 through the injection ports 36, the speed of the rising current of the compressed air is strengthened to cause an eddy current S in the large diameter part 34. Thus since the flow of the compressed air becomes brisk, the mixing of the compressed air and fuel is improved, and combustion is thereby accelerated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber of an internal combustion engine of a sub-chamber combustion type.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a combustion chamber of a conventionally known sub-chamber combustion type internal combustion engine, and FIGS.
-B shows a cross section.

As shown in FIGS. 4 and 5, a cylinder 12 is formed in a cylinder block 11 of an internal combustion engine, and a piston 13 is vertically reciprocally fitted in the cylinder 12. A cavity (recess) 14 is formed on the top of the piston 13. A cylinder head 16 is fixed to the upper part of the cylinder block 11 via a gasket 15 to cover the upper part of the cylinder 12, thereby forming a main combustion chamber 17.

A housing 18 is provided upright in the cylinder head 16 at the center of the cylinder 12, and the sub-chamber 1 is provided therein.
9 is formed. A fuel injection valve 20 and a glow plug (not shown) are attached to the upper portion of the sub chamber 19. The sub chamber 19 formed in the housing 18 has a columnar shape, and is composed of a small diameter portion 21 at the bottom and a large diameter portion 22 at the top. A plurality of injection holes 23 are formed in the lower end of the housing 18 at equal intervals in the circumferential direction, and project into the combustion chamber 17. Therefore, sub-chamber 1
9 and the main combustion chamber 17 communicate with each other through a plurality of injection holes 23.

Thus, during operation of the engine, the air in the main combustion chamber 17 is compressed by the piston 13 in the compression stroke, and this compressed air flows into the sub chamber 19 through the plurality of injection holes 23. On the other hand, fuel is injected from the fuel injection valve 20 into the sub chamber 19, and the atomized fuel and compressed air are mixed to form a mixture, which is ignited by the glow plug and burned. Also,
The unburned fuel ejected from each of the injection holes 23 of the sub chamber 19 and the air in the main combustion chamber 17 are mixed by gas injection from the sub chamber 19.

[0006]

In a combustion chamber of an internal combustion engine having a sub-chamber, in order to improve the fuel consumption, the sub-chamber 1
It is important to reduce the throttling loss and heat loss of the sub chamber 19 by increasing the passage area of the injection port 23 of No. 9. To do so, sub-chamber 1
It is necessary to promote combustion in the fuel cell 9, and the mixture of fuel and air must be created well. In the combustion chamber of the above-described conventional sub-chamber combustion type internal combustion engine, compressed air flows into the sub-chamber 19 through the plurality of nozzles 23 in the compression stroke and rises as indicated by arrow S in FIG. Since the swirling flow is generated in the large diameter portion 22 of the sub chamber 19 by the flow, the compressed air is well mixed with the fuel injected from the fuel injection valve 20.

However, if the cross-sectional area of the small-diameter portion 21 of the sub chamber 19 is large to some extent, the intervals of the plurality of injection holes 23 formed at the lower end of the sub-chamber 19 become wide, and the velocity of the vortex S described above weakens, and compressed air and fuel are injected. The mixing with the fuel injected from the valve 20 does not go well, and the combustion in the sub chamber 19 deteriorates. Then, it is not possible to secure the jet energy necessary for forming the air-fuel mixture and promoting combustion in the main combustion chamber 17,
There was a problem that combustion of the engine deteriorated and fuel consumption and smoke emission deteriorate.

Therefore, as shown in FIG. 6, the cross-sectional area of the small diameter portion 21 of the sub chamber 19 is reduced to narrow the intervals between the plurality of nozzles 23, so that the compressed air is directed to the large diameter portion 22 of the sub chamber 19. It is considered to increase the speed of the rising vortex S.
However, if the intervals between the plurality of injection holes 23 are narrowed, the wall thickness of the injection holes 23 adjacent to each other will be reduced, and the injection holes 23 will interfere with each other, and the peripheral portion (housing 18) of the injection holes 23 at the time of combustion in the main combustion chamber 17. Since it is exposed to high temperatures, melting and cracking are likely to occur, and there was a problem that the reliability of the engine could not be secured.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a combustion chamber of an internal combustion engine having a sub chamber for improving the fuel efficiency and reliability of the engine.

[0010]

A combustion chamber of an internal combustion engine having a sub-chamber of the present invention for achieving the above object has a sub-chamber having a plurality of nozzles at a lower portion, which is located above the main combustion chamber. In addition, in a combustion chamber of an internal combustion engine having a sub chamber communicating with the main combustion chamber via the injection port, the sub chamber has a small diameter portion formed on the injection port side and a large diameter portion adjacent to the small diameter portion. And a narrowed portion having a smaller cross-sectional area than the small-diameter portion is provided between the small-diameter portion and the large-diameter portion so as to communicate with each other.

[0011]

By providing a narrowed portion having a smaller cross-sectional area than the small-diameter portion between the small-diameter portion and the large-diameter portion forming the sub-chamber so as to communicate with each other, compressed air is compressed from a plurality of nozzles to the small-diameter portion of the sub-chamber. Flow into the section, and the speed of the upward flow is strengthened at the throttle section to generate a swirl flow at the large diameter section, mixing with fuel becomes good and combustion is promoted, and the jet energy to the main combustion chamber is increased. And the combustion is promoted also in the main combustion chamber.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic view of a combustion chamber of an internal combustion engine having a sub chamber according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. It should be noted that the members having the same functions as those of the related art are designated by the same reference numerals, and the duplicate description will be omitted.

As shown in FIGS. 1 and 2, a piston 13 is reciprocally fitted in the cylinder 12 of the cylinder block 11, and a cavity 14 is provided at the top of the piston 13.
Are formed. And the cylinder 12 and the piston 1
3 and the cylinder head 16 form a main combustion chamber 17. A housing 31 is provided upright in the cylinder head 16 at the center of the cylinder 12, a sub chamber 32 is formed inside, and a fuel injection valve 20 is attached to the upper part.

The sub chamber 32 has a cylindrical shape, has a lower small diameter portion 33 and an upper large diameter portion 34, and has a narrowed portion 35 having a smaller cross-sectional area than the small diameter portion 33 between the small diameter portion 33 and the large diameter portion 34. Is formed, the small diameter portion 33 and the large diameter portion 34 are communicated with each other. That is, when the cross-sectional area of the small-diameter portion 33 is a, the cross-sectional area of the large-diameter portion 34 is b, and the cross-sectional area of the narrowed portion 35 is c,
The magnitude relationship is c <a <b. The lower end of the housing 31 has a plurality of nozzle holes 3 at even intervals in the circumferential direction.
6 is formed and protrudes into the combustion chamber 17, so that the sub chamber 3
2 and the main combustion chamber 17 communicate with each other through a plurality of injection holes 36.

Thus, in the compression stroke of the engine, the air in the main combustion chamber 17 is compressed by the piston 13, and this compressed air flows into the sub chamber 32 through the plurality of injection holes 36, while
The fuel injected from the fuel injection valve 20 is injected into the sub chamber 32. Then, the fuel and the compressed air are mixed to form an air-fuel mixture, which is ignited and burned.

At this time, the compressed air flows into the sub chamber 32 through the plurality of injection holes 36, but as shown in FIG. A swirl S is generated at the portion 34. In this way, the flow of the compressed air becomes active, so that the mixture with the fuel becomes good and combustion is promoted. Further, since the mixing of the fuel and the compressed air in the sub chamber 32 becomes good and the combustion is promoted, the main combustion chamber 1
The jet energy to 7 increases, and combustion is promoted also in this main combustion chamber 17.

Further, the velocity of the compressed air is strengthened in the throttle portion 35 to generate the vortex S, and the mixing with the fuel is improved, so that the vortex S becomes different due to the difference in cross-sectional area between the small diameter portion 33 and the large diameter portion 34. Eliminates the need to adjust speed. Therefore, by increasing the cross-sectional area of the small-diameter portion 33 and widening the intervals between the plurality of injection ports 36, the wall thickness between the injection ports 36 adjacent to each other will not be thinned, and the injection ports during combustion in the main combustion chamber 17 will not occur. Even if the peripheral portion of 32 is exposed to high temperature, melting loss or cracks do not occur, and the reliability of the engine is secured.

FIG. 3 shows a cross section of a sub chamber representing a combustion chamber of an internal combustion engine having a sub chamber according to another embodiment of the present invention. In addition,
The members having the same functions as those in the above-described embodiment are designated by the same reference numerals, and the duplicated description will be omitted.

3 (a), (b), and (c) are the same as the above-mentioned embodiment except that the shape of the sub chamber, in particular, the shape of the throttle is changed. It is possible to achieve the action and effect.

That is, in the sub chamber 41 shown in FIG. 3A, the narrowed portion 44 having a smaller cross-sectional area than the small diameter portion 42 is formed between the small diameter portion 42 and the large diameter portion 43. As in the example, no tapered portion is formed between the small diameter portion 42 and the narrowed portion 44, and no tapered portion is formed between the large diameter portion 43 and the narrowed portion 44. Therefore, the velocity of the upward flow of the compressed air is high, and the sub chamber 31 can be easily processed.

In the sub chamber 51 shown in FIG. 3 (b), a narrowed portion 54 having a smaller cross-sectional area than the small diameter portion 52 is formed between the small diameter portion 52 and the large diameter portion 53. As in the example, the small diameter portion 52 and the large diameter portion 53 are tapered portions 5
It is continuous by 5,56. Therefore, the flow of the compressed air becomes smooth and the throttle loss can be reduced.

Further, in the sub chamber 61 shown in FIG. 3 (c), a narrowed portion 64 having a smaller cross-sectional area than the small diameter portion 62 is formed between the small diameter portion 62 and the large diameter portion 63. As in the example, the small-diameter portion 52 and the large-diameter portion 53 are continuous by the stage portion 65. Therefore, the flow of compressed air becomes smoother.

[0024]

As described above in detail with reference to the embodiments, according to the combustion chamber of the internal combustion engine having the auxiliary chamber of the present invention,
A sub-chamber having a plurality of nozzles in the lower part is located above the main combustion chamber and communicates with the main combustion chamber through the nozzle, and the sub-chamber has a small diameter portion on the nozzle side and a large diameter portion adjacent to the small diameter portion. Have and
Since the narrowed portion having a smaller cross-sectional area than the small diameter portion is provided between the small diameter portion and the large diameter portion so as to communicate them, when the compressed air flows into the sub chamber through the injection port, The velocity of the ascending flow is intensified to generate a vortex in the large diameter portion, the flow of the compressed air becomes active, the mixing with the fuel becomes good, and the combustion in the sub chamber can be promoted.
When the combustion in the sub chamber is promoted, the jet energy to the main combustion chamber increases, and the combustion can be promoted also in the main combustion chamber. Also, by increasing the cross-sectional area of the small diameter part, it is possible to secure sufficient wall thickness with the adjacent nozzles, prevent melting and cracking around the nozzles, and improve engine reliability. Can be planned.

[Brief description of drawings]

FIG. 1 is a schematic view of a combustion chamber of an internal combustion engine having a sub chamber according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view of a sub chamber representing a combustion chamber of an internal combustion engine having a sub chamber according to another embodiment of the present invention.

FIG. 4 is a sectional view of a combustion chamber of a conventional sub-chamber combustion type internal combustion engine.

5 is a sectional view taken along line BB of FIG.

FIG. 6 is a cross-sectional view of a sub chamber in which the cross-sectional area of the small diameter portion is reduced.

[Explanation of symbols]

 13 piston 17 main combustion chamber 20 fuel injection valve 31 housing 32, 41, 51, 61 sub-chamber 33, 42, 52, 62 small diameter portion 34, 43, 53, 63 large diameter portion 35, 44, 54, 64 throttle portion 36 Spout

Claims (1)

[Claims] 1. A combustion chamber of an internal combustion engine, wherein a sub-chamber having a plurality of nozzles in a lower portion is located above the main combustion chamber and has a sub-chamber communicating with the main combustion chamber through the nozzles. The sub-chamber has a small-diameter portion formed on the injection port side and a large-diameter portion adjacent to the small-diameter portion, and a narrowed portion having a cross-sectional area smaller than the small-diameter portion has the small-diameter portion and the large-diameter portion. A spark ignition gas internal combustion engine, characterized in that both are provided in communication with each other.