JPS6011624A - Combustion chamber structure for direct injection type diesel engine - Google Patents

Abstract

PURPOSE:To accelerate a complete combustion of injection fuel as well as to aim at improvements in engine performance and smoke emission output, by making up a fuel oil air chamber in the upper peripheral part of a combustion chamber at the downstream side in a flow direction of a swirl from a fuel range to collide with an inner surface of the combustion chamber. CONSTITUTION:A swirl S is led into a chamber and whirled inside the chamber, while injection fuel F is blown inside and in order to produce an air-fuel mixture, a combustion chamber 5 is formed by a piston 2 being opened upward fronting on a cylinder head 3. And, at an upper peripheral edge part of this combustion chamber 5, each of fuel oil air chambers 7 is formed at the downstream side of a flow direction of the swirl S from a fuel range A colliding with a peripheral side 5a of the combustion chamber 5. These fuel oil air chambers 7 are formed in a piston head 2a corresponding to each of nozzle holes 4a of an injection nozzle 4. In addition, each of these fuel oil air chambers 7 is made up of a concave part stretching outward the diametral direction from the combustion chamber 5 whereby air is made to be stayable therein.

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to the construction of a combustion chamber M?i of a direct injection diesel engine, and in particular promotes complete combustion of the injection q1 combustion slope to improve engine performance and reduce smoke. The present invention relates to a combustion V structure of a direct injection diesel engine that can achieve improvements.

[Technical background of the invention and its problems] Generally, as shown in FIG. 1, a direct injection diesel engine compresses intake air flowing into a cylinder 1 with an ascending piston 2 to reach high temperature and high pressure. When the piston 2 reaches the vicinity of the top dead center, the twist r1 is directly injected from the injection nozzle 4 provided in the cylinder head 3, thereby causing spontaneous ignition and combustion.

Conventionally, in this type of diesel engine, a combustion chamber 5 is formed in a piston head 2a facing a cylinder head 3 by recessing a substantially central portion of the piston head 2a. This combustion chamber 5 functions to sufficiently mix and vaporize the air and the @ fuel by the swirl, thereby increasing the combustion efficiency.

By the way, conventionally, immediately after the start of combustion, the flame of the fuel injected from each injection nozzle 4 and colliding with the side wall of the combustion chamber 50 is transmitted from the combustion chamber 5 to the head clearance (the piston 2 is 1 - dead). There is a problem in that when this point is reached, the gas spreads into the gap C formed between the cylinder head 3 and the piston head 2a, resulting in incomplete combustion and worsening smoke.

Regarding combustion, it is desirable that the head cleaner 7 is divided by 1 and combustion is achieved within the closed combustion chamber 5 of a predetermined volume.
A gasket 1- is interposed between the gasket 1- and the gasket 1- to ensure air-tightness and liquid-tightness, and a clearance C approximately corresponding to the thickness of the gasket 1- is formed.

The combustion chamber 5 takes in a sufficient amount of intake air to increase the combustion efficiency within it, and if the flame spreads to the narrow head cleaner 7 C with a small amount of air (oxygen amount), there will be a lack of oxygen and incomplete combustion will occur. It will happen.

[Object of the Invention] The present invention was devised in view of the above-mentioned problems, and its purpose is to promote complete combustion of the injected fuel 1 and
The object of the present invention is to provide a combustion chamber structure for a direct injection diesel engine that can improve the performance of engine breaks and improve smoke.

The Ministry of Invention has discovered that most of the flame that spreads to the head clearance is caused by the swirl from the adhering part of the fuel that has been injected from each nozzle of the injection nozzle and collided with the peripheral side wall of the combustion chamber (hereinafter referred to as the "fuel area"). By focusing on the fact that the flame is formed on the downstream side in the flow direction, and by forming an air pocket only in the part where the flame spreads and securing the minimum necessary amount of oxygen, the amount of air in the combustion chamber is not significantly reduced. The present invention was completed by discovering that it is possible to completely burn the flame that spreads to the rad rearance.

[Embodiment 1 of the Invention A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.
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As shown in FIGS. 2 and 3, 5 is the piston head 2.
The combustion chamber 5 is formed by being sunk in a, and in this embodiment, a relatively deep combustion chamber 5 is shown. The combustion chamber 5 is open at the top facing the cylinder head 3 equipped with the injection nozzle 4, and is open at the side in order to introduce the swirl S into the chamber and take in the injected fuel F to generate an air-fuel mixture. The section and the bottom section are defined by a peripheral side wall 5a and a bottom wall 5b, respectively.

In the upper peripheral portion 5C of the combustion chamber 5 formed in this way,
An auxiliary combustion air chamber 7 is formed downstream in the flow direction of the swirl S from the fuel area A that collides with the peripheral wall 5a of the combustion chamber 5. These auxiliary combustion air chambers 7 are formed in the piston head 2a facing the cylinder head 3, corresponding to the injection ports 4a of the injection nozzle 4 through which the fuel F is injected. In this embodiment, the auxiliary combustion air chamber 7... is the combustion chamber 5.
It is formed of a concave portion that continues from the head to the outside in the radial direction, and is configured to form a cavity deeper than the head clearance C so that air can be retained therein. In addition, these auxiliary combustion air chambers 7... provide a sufficient amount of air to the flame B... which spreads from the fuel area A... to the downstream side of the swirl S, while increasing the amount of air charged in the combustion chamber 5 beyond the necessary amount. Side portions 7a along the circumferential direction of the combustion chamber 5 are partitioned into the piston head 2a and formed to have a predetermined volume so as not to be reduced.

The above configuration is based on the following considerations. That is, the spout 4a.
The atomized fuel f injected from ... and mixed and vaporized by the swirl S before reaching the circumferential wall 5a is exposed to sufficient air in the combustion chamber 5, so that it is easily combusted completely. However, the peripheral wall 5
In the fuel area Δ... formed by the fuel that collided with a, the fuel density is high from the perspective of the entire combustion chamber 5 and is in an excessive amount relative to the amount of air in the vicinity, and in the fuel area A... The formed flame B... tends to undergo incomplete combustion. Therefore, fuel range A
It is necessary to supply a sufficient amount of air to the flame B, which is formed by... and spreads to the head clearance C on the downstream side of the swirl S in the flow direction, and is not particularly necessary for other parts. be. On the contrary, the auxiliary combustion air chamber 7.
The formation of... reduces the combustion rate in the combustion chamber 5 and the average effective pressure in the cylinder (hereinafter, [Pmej
That's what it means. ) and may worsen the smoke.

Next, the operation of the present invention will be described.

As shown in the figure, a swirl S is swirled inside the combustion chamber 5, and fuel is injected. vaporized.

On the other hand, on the peripheral side wall 5a of the combustion chamber 5, some of the fuel that has collided without being mixed and vaporized adheres and stays there to form fuel rows A... Thereafter, as a flame kernel is generated in the air-fuel mixture and the flame propagates, flame B... is also generated in the fuel area A... These flames B... are blown away by the swirl S and spread to the head clearance C on the downstream side. At this time, in the present invention, the flame B... is completely suppressed as much as possible by the air retained in the auxiliary combustion air chamber 7... formed at the position where the flame B... spreads during the compression stroke. It can be burned. Therefore, it is possible to improve pme and improve smoke.

``Modified Embodiment 1'' FIGS. 4 to 7 show a modified example of the above embodiment.

What is shown in FIGS. 4 and 5 is a case where the auxiliary combustion air chamber 7 is formed in the cylinder head 3 facing the piston head 2a, and even in this modification, the upper part of the combustion chamber 5 is divided. The cylinder head 3 is formed with a concave portion that continues outward in the radial direction of the combustion chamber 5, and is configured to allow air to stagnate therein. The configuration of the sensor is the same as in the above embodiment. In this modification, the combustion chamber 5 and the injection port 4a of the injection nozzle 4...
Due to the relationship between the auxiliary combustion air chamber 7...
. . ., there is a problem that it interferes with the intake valve 8 and the antagonistic valve 9. If the intake valve 8 and the exhaust valve 9 are formed to have high strength, an auxiliary combustion air amount may be formed in these.

The configuration shown in FIGS. 6 and 7 solves the problems of the above-mentioned modification, and the auxiliary combustion air chamber 7 at the position interfering with the intake valve 8 and the exhaust valve 9 is located in the piston head 2a, and the other The auxiliary combustion air chamber 7 is formed in the cylinder head 3.

It goes without saying that even in the modified embodiments described above, the same effects as in the above embodiments can be achieved.

[Effects of the Invention] Below-11 In short, according to the present invention, the following excellent effects are exhibited.

(1) An auxiliary combustion air chamber was formed to supply air to the flame that spreads to the head clearance for complete combustion.
It promotes complete combustion of the injected fuel and improves engine performance.2.It can improve smoke.

(2) The structure is simple and can be easily adopted.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a direct injection diesel engine, FIG. 2 is a plan view showing a preferred embodiment of the present invention, FIG. 3 is a sectional view taken along the line ■-■ in FIG. 5 is a plan view showing a modified embodiment, FIG. 5 is a sectional view taken along the line v-V in FIG. 4, FIG. 6 is a plan view showing another modified embodiment, and FIG. 7 is a -■ is a sectional view taken along the line. In the figure, 2a is a piston head, 3 is a cylinder head, and 4 is a piston head.
4a is an injection nozzle, 4a is its injection port, 59- is a combustion chamber, 5a is an inner circumferential wall thereof, 5C is an upper periphery thereof, 7 is an auxiliary combustion air chamber, A is a fuel area, and S is a swirl. Patent Applicant: Isuzu Motors Co., Ltd. Representative Patent Attorney Nobuo Kinutani 10 - Engraving of drawings (no changes to the content) 2nd page No. 6Z Procedural official document (method) November 90, 1980 Commissioner of the Patent Office Wakasugi Mr. Kazuo 1, Indication of the incident, Patent Application No. 118062-1983? 1. Title of the invention Combustion chamber structure of a direct injection diesel engine], Relationship to the amended case Patent applicant (017) Isuzu Motors Co., Ltd. 1 Agent postal code 105 1-6-7 Atago, Minato-ku, Tokyo No. Atagoyama Lawyer Building 5゜Date of amendment order October 25, 1988 (Shipping port) 3. Drawings subject to amendment ζ Contents of amendment (1) Appropriate drawings will be submitted as shown in the attached sheet. 3. Attached list of class M (1) drawings 1 copy 173-

Claims (4)

[Claims] (1) In the combustion chamber of a direct injection type diesel engine, an auxiliary combustion air chamber is formed at the upper peripheral edge of the combustion chamber downstream of the fuel area colliding with the wall of the combustion chamber in the flow direction of the swirl. Combustion chamber structure of ill sword type diesel engine. (2) The combustion chamber structure of a direct injection diesel engine according to claim 1, wherein the auxiliary combustion air chamber is formed by a concave portion facing the cylinder head in a piston head that partitions the combustion chamber. (3) The direct injection diesel engine according to claim 1 or 2, wherein the auxiliary combustion air chamber is formed by a concave portion facing the piston head in the cylinder head that partitions the combustion chamber. Combustion chamber structure. (4) Combustion of the direct injection diesel engine according to claim 1, 2 or 3, wherein the auxiliary combustion air chambers are respectively formed to correspond to the injection ports of the injection nozzles that inject the fuel. Chamber structure.