JPS6189919A - Combustion chamber of direct injection type diesel engine - Google Patents

Abstract

PURPOSE:To control generation of unburned product and pale smoke and to reduce noise, by furnishing a main nozzle to inject fuel into a main combustion chamber and a secondary nozzle to inject fuel into a secondary combustion chamber, in a fuel injection nozzle arrangement. CONSTITUTION:A main combustion chamber 2 and a secondary combustion chamber 3 are furnished at the top of a piston 1. In the main combustion chamber is furnished a fuel injection nozzle system 4 which has a main nozzle 13 to inject fuel into the main combustion chamber 2, and a secondary nozzle 11 to inject fuel into the secondary combustion chamber 3 when the main nozzle is closed. A connecting passage is arranged through which the main combustion chamber 2 and the secondary combustion chamber 3 are connected. Thus, ignition performance in the low load engine operation is improved, and pale smoke can be controlled to reduce unburned product.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a direct injection diesel internal combustion engine, and in particular, the blue-white smoke generated in the combustion chamber during low to high load operation and the combustion generated thereby. In order to prevent unburned products (HC) from adhering to the interior walls, to quickly ignite the fuel injected into the combustion chamber, and to burn it more slowly, the main combustion chambers are installed in parallel and in communication with each other at the top of the piston. The present invention relates to a direct injection diesel engine combustion chamber having a combustion chamber and an auxiliary combustion chamber.

[Prior Art] In general, direct injection diesel internal combustion engines have high combustion efficiency and
Although it has advantages such as low exhaust temperature, it has drawbacks such as high explosion pressure, high imaging and noise.

In order to improve these drawbacks, the top of the piston is recessed to form a combustion chamber, and while a swirl is generated within the combustion chamber, fuel is injected and collides with the inner wall of the combustion chamber to evaporate it. The so-called M
AN-M type engines are known.

However, since the above-mentioned M type engine evaporates and burns the injected fuel, under conditions where the atmospheric temperature is low and the engine cooling water temperature is low, the wall temperature of the combustion chamber is low and sufficient M
It cannot have the R capability, and a lot of unburned fuel is generated in the combustion chamber, which is discharged and produces blue-white smoke. Furthermore, even when the air and water temperatures are at room temperature, in the case of light and negative conditions at the same time, such as when idling, a large amount of unburned matter (HC) is generated due to the low wall temperature, which worsens the combustion condition. It was a factor.

It has also been confirmed that this defect occurs even in lean conditions when fuel is injected in a toroidal combustion chamber under controlled conditions, and the reason for this is that after ignition, flame propagation cannot occur normally and the fuel blows out. .

In order to eliminate such drawbacks, Japanese Patent Laid-Open No. 49-50307 (Conventional Example A), Japanese Utility Model Application No. 51-33221 (Conventional Example B), and Japanese Patent Laid-Open No. 57-41417 (Conventional Example C) have been proposed.
) have been proposed, and these are explained below.

In conventional example a, the piston top 1 is deeply recessed to form the main combustion chamber 2 of a so-called MAN-M type engine, as shown in FIG. , a communication passage 21 communicating between the combustion chambers 2, 3 is formed in the cylinder head 20.

On the other hand, as shown in FIG. 11, the main combustion chamber 2 and the DI combustion chamber 3 are formed in the piston 6 and the cylinder head 20, respectively, as in the conventional example a, and the piston 6 is at the top dead center position. Communication passages 21 connecting them are formed tangentially to each other, and swirl chambers 22 are formed therein.

A fuel injection nozzle 4 is provided in the conventional example a and the conventional example No. If fuel injection is performed to mainly inject fuel into the main combustion chamber 2 during high-load operation, the combustion chamber ratio (fuel/air) will be increased during low-load operation to cause excessive combustion, thereby reducing combustion. The purpose is to suppress the generation of unburned matter (HC').

However, in the above-mentioned conventional examples a and 2, the generation of unburned HC is suppressed at low loads, and at the same time, the HC is injected into the main combustion chamber 2 from the communication passage 21 at high loads. Since the fuel spray that is generated is ignited by the combustion gas that ignites and burns in the auxiliary combustion chamber 3, it loses its precious power, resulting in incomplete combustion in the main combustion chamber 2, which leads to smoke generation and reduces combustion efficiency. I was letting it happen.

Furthermore, in order to eliminate this drawback, conventional example C shown in FIG.
This proposal includes a cavity 24 formed in at least one of the piston 6 and the cylinder head 20 into which the intake swirl S is introduced, and a vortex flow communicating with the cavity 24 through a vortex generation throttle hole 25. The auxiliary chamber 26 and a part of the injected fuel are connected to the inner wall 24 of the cavity 24.
A is equipped with a fuel injection valve 4 that injects the remaining fuel into the vortex sub-chamber 26 through the throttle hole 25, and performs rapid combustion in the vortex sub-chamber 26 and slow combustion utilizing fuel evaporation in the cavity 24. A combustion chamber of an internal combustion engine, in which the throttle hole 25 is opened in the swirl S direction with respect to the cavity 24, and has a sub throttle hole facing the fuel injection direction and a main throttle hole facing the swirl direction with respect to the cavity 24. A part of the combustion chamber is made into a vortex-type vortex chamber in which a vortex is formed by pushing through the piston compression process, and part of the 1st injection fuel is rapidly combusted in the sub-constriction, and the remaining injected fuel is burned out. The fuel is injected onto the inner wall 24a of the cavity 24, and the combustion gas rapidly combusted in the auxiliary chamber 26 is ejected into the cavity 24 to generate a large air flow, thereby turning the fuel adhering to the inner wall 24a of the cavity 24 into a film. This is an attempt to cause slow combustion by elongating the fuel and promoting fuel evaporation as a result.

However, in conventional example C configured as described above, the fuel injected onto the inner wall 24a of the cavity 24 is not evaporated due to the rapid combustion gas flow in the auxiliary chamber 26 formed below the cavity 24 and the heat generated thereby. There is a possibility of overachieving, and it is thought that this becomes even more noticeable under high loads. That is, promoting fuel evaporation in the cavity 24 generates a large amount of premixture with excellent ignitability, and this leads to
When ignited by the combustion gas, rapid combustion also occurs within the cavity 24, resulting in an increase in combustion pressure, which has the disadvantage of causing abnormally high noise.

[Object of the Invention] The present invention was devised to solve the above-mentioned problems, and an object of the present invention is to reduce the amount of unburned matter (1-I) generated during low load.
To provide a direct-injection diesel combustion chamber that suppresses the generation of blue and white smoke, reduces noise over a wide range from low angle loads to high loads, and achieves slow combustion and is quiet. There is a particular thing.

[Summary of the Invention] In order to achieve the above object, the present invention includes a main combustion chamber recessed in the top of the piston, and a main combustion chamber recessed in the top of the piston that is arranged in parallel to communicate with the main combustion chamber. and a main combustion chamber that injects fuel in the direction of the swirl generated in the main combustion chamber, and a main combustion chamber that injects fuel in the direction of the swirl generated in the main combustion chamber. a fuel injection nozzle having a Dj nozzle that injects fuel facing in the direction of the swirl, the auxiliary combustion chamber is formed to have a smaller capacity than the main combustion chamber,
The combustion chambers have, for example, a circular cross-sectional shape with an open upper part, a part of the peripheral side wall thereof is open and communicated with each other, and the fuel injection nozzle is provided with, for example, a needle valve, and the needle valve is a needle valve. The auxiliary nozzle is configured to open when the lift is below a predetermined level, and the main nozzle opening is opened when the lift is above a predetermined level, and the fuel injection nozzle is connected to the main combustion chamber and the auxiliary combustion chamber to form a 5-bar continuous part. The main nozzle faces the inner wall of the combustion chamber, and the auxiliary nozzle faces the inner wall of the auxiliary combustion chamber and downstream of the swirl generated within the combustion chamber. The atomized fuel spray collides with the inner wall of the auxiliary combustion chamber and is effectively mixed with the generated swirl to form a premixed fuel film with excellent ignitability, resulting in slow and slow ignition. This can be achieved quickly, preventing a sudden pressure rise in the combustion chamber.Furthermore, at high loads, fuel with a larger particle size than the above fuel spray is injected from the main nozzle toward the inner wall of the main combustion chamber, causing a drop in the wall surface. The fuel film is evaporated by the heat received from the wall surface and mixed with the swirl generated in the main combustion chamber to generate the premixture, while the premixture is generated in the sub-combustion chamber. It is quickly ignited by the combustion gas, and the flame propagates in the swirl direction, suppressing the pressure rise in the main and auxiliary combustion chambers, reducing noise and slow combustion, and significantly reducing unburned products (HC). It is something that makes you

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be specifically described based on the accompanying drawings.

As shown in FIGS. 1 to 3, the piston top 1 includes:
A main combustion chamber 2 and a sub-combustion chamber 3 are formed by being depressed from this. The main and auxiliary combustion chambers 2 and 3 each have a circular cross-sectional shape with an open top, and are arranged in parallel on the piston top 1, and are connected to the main combustion chamber 2 and the auxiliary combustion chamber 3. Parts of the circumferential walls 2a and 3a are open to communicate with each other. Further, the volume of the sub-combustion chamber 3 is smaller than that of the main combustion chamber 2, and specifically, the circular cross section of the main combustion chamber 2 is formed to have a smaller diameter than the circular cross section of the sub-combustion chamber 3, and the main combustion chamber 3 has a smaller diameter. The auxiliary combustion chamber 3 is recessed shallower than the combustion chamber 2.

As shown in FIG. 4, a fuel injection nozzle 4 is provided in the communication portion between the main combustion chamber 2 and the auxiliary combustion chamber 3 formed in this way so as to face it, and this fuel injection nozzle 4 is not shown. Attached to the cylinder head. Further, the main components of the fuel injection nozzle 4 include a needle valve 10 having a tapered portion 9 that sits movably up and down on a valve seat 8 in a nozzle body 7 attached to the cylinder head and opens and closes the valve seat 8; The fuel spray opened from the seat 8 and injected from the inner wall 3a of the sub-combustion chamber 3 as shown in FIG. 1 is injected toward the downstream side of the swirl S generated within the sub-combustion chamber 3. A sub-nozzle 11 is formed to open at the inner end of the nozzle body 7 and along the axial direction of the needle valve 10.
The main combustion chamber is designed to accommodate a reduced diameter part 12 of the main combustion chamber 2 and to inject fuel onto the inner wall 2a of the main combustion chamber 2 and downstream in the direction of the swirl S generated therein as shown in FIG. It is formed from the nozzle 13.

The sub-nozzle 11 and the main nozzle 13 are the needle valve 1.
Each frontage is designed to be opened with a lift amount of 0,
When the load of the engine is low, the sub-nozzle 11 is opened when the engine lift is below a predetermined lift, and the main nozzle 13 is opened when the lift is above the predetermined lift, and the fuel required for high-load operation is supplied to the combustion chambers 2 and 3, respectively.

Therefore, as shown in FIG. 1, the swirl S sucked in from a swirl boat (not shown) is generated while being compressed in the main combustion chamber 2 and the sub-combustion chamber 3 of the piston top 1. When the engine is under low load, the needle valve 10
The auxiliary nozzle 11 is opened by the lift of , and the fuel spray is made to collide with the inner wall 3a of the auxiliary combustion chamber 3 as shown in FIG.
As a result, atomized fuel spray is formed, and the spray flows along the swirl S direction of the sub-combustion chamber 3 to form a fuel film H as shown in FIG. fuel film H
A part of the mixture receives heat from the inner wall 3a of the auxiliary combustion chamber 3 and evaporates, and is effectively mixed with the swirl S to generate the premixture F shown in FIG. 1 with excellent ignitability. By igniting and burning the flame, the remaining fuel film H
ignites quickly and burns rapidly. Further, since the particle size of the spray injected from the sub-nozzle 11 whose nozzle diameter is set to be small is atomized and small, it instantly evaporates and ignites in the compressed high-temperature air as shown in FIG. On the other hand, since this spray is directed toward the inner wall 3a of the sub-combustion chamber 3, most of the fuel is distributed along the inner wall 3a.

Furthermore, the ignited thermal energy causes the fuel distributed on the wall surface to gradually evaporate and burn. The sub-combustion chamber 3 is separated from the main combustion chamber 2, and most of the combustion gas E is trapped within the sub-combustion chamber 3 by the swirl S within the sub-combustion chamber 3, and combustion within the sub-combustion chamber 3 is rapidly achieved. As a result, combustion leakage increases, and the generation of blue-white smoke and unburned matter (HC) can be suppressed. Therefore, when the load is low, the average combustion temperature in the sub-combustion chamber 3 increases, and as a result, the generation of blue-white smoke and unburned matter (HC) can be suppressed.

Furthermore, under high load, as shown in FIG. 7, the fuel spray is directed from the main nozzle 13 toward the inner wall 2a of the main combustion chamber 2 and toward the downstream direction of the swirl S, as shown in FIGS. 2
As shown in the above, fuel is injected, and a fuel film H and a premixture F are generated in the same manner as described above. At this time, a part of the combustion gas E in the auxiliary combustion chamber 3 propagates into the premixture F in the main combustion chamber 2, and the fuel film H is further ignited and combusted. However, the fuel injected from the main nozzle 13 has a larger diameter than the fuel spray injected from the auxiliary nozzle 11 and has a greater penetration force, so the premixture generated by mixing the evaporated fuel and the swirl S is It is not produced in excess, and even if it ignites, rapid combustion cannot occur in the main combustion chamber 2. Therefore, the remaining fuel film H is quickly evaporated by the heat generated by the ignition of the premixture F. As this steam is combusted, it is slowly combusted as shown in Figure 8, thereby suppressing the sudden pressure rise in the main combustion chamber 2, further reducing noise and suppressing diesel knock. Also, the higher the load, the more the main nozzle 1
3, the amount of fuel injected increases, and at most 90% or more is injected, so the above effect is reliably achieved and D
J combustion reaches its final state, and the inflowing flame ensures ignition.

FIG. 9 is a diagram showing a comparison between a conventional VAN-M system engine and an embodiment of the present invention, and shows the relationship between combustion chamber pressure (bar) and crank angle (°).
In contrast to the system engine (Pl), the embodiment (P2) of the present invention has an earlier ignition timing of the fuel injected from the sub-nozzle 11, and also reliably ignites the fuel injected from the main nozzle 13. Combustion pressure is relatively motoring waveform line (
The upper limit is in the tangential direction of PO) (combustion chamber pressure when fuel is cut), and the curve is smoother than that of the MAN-M engine (Pl), which indicates that slow combustion has been achieved. This shows that. Further, as shown in the figure, it can be confirmed that when the fuel from the sub-nozzle 11 is reliably ignited, fuel is injected from the main nozzle 13 and is quickly ignited.

[Effects of the Invention] As detailed above, the present invention provides the following excellent effects.

(1) By arranging a main combustion chamber and a sub-combustion chamber in parallel at the top of the piston and communicating with each other to form a combustion chamber, when the engine is under low load, ignition delay is short and slow combustion is achieved by sub-combustion. This can be achieved indoors, and the combustion leakage can suppress blue-white smoke υ1 and reduce the amount of unburned matter (1-10).

(2) By providing a connecting part that communicates with the main combustion chamber and the auxiliary combustion chamber, a part of the combustion gas in the auxiliary combustion chamber enters the main combustion chamber, and the combustion gas is injected into the main combustion chamber. Since the evaporated premixture and fuel film can be ignited and burned to achieve rapid and slow combustion, noise can be prevented over a wide range of loads from low to high loads, and a quiet direct injection diesel combustion chamber can be provided. .

(3) Low cetane number or low quality fuel mixed with alcohol can be used.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a preferred embodiment of the present invention, FIG. 2 is a schematic sectional view showing the injection direction of the fuel injection nozzle that injects fuel into the main combustion chamber and the D combustion chamber of the present invention, and FIG. The figure is a schematic perspective view showing the main combustion chamber and the sub-combustion chamber of the embodiment of the present invention formed at the top of the piston, FIG. 4 is a schematic sectional view of the fuel injection nozzle shown in FIG. 2, and FIG. 8 to 8 are diagrams showing the process of fuel injected into the main combustion chamber and auxiliary combustion chamber of the present invention until ignition combustion, and FIG. 9 is a diagram showing a conventional VAN-M type engine and an embodiment of the present invention. 10 to 12 are diagrams showing conventional examples. In the figure, 1 is the piston top, 2 is the main combustion chamber, 3 is the sub-combustion chamber, 4 is the fuel injection nozzle, 11 is the sub-nozzle, and 13 is the main nozzle. Patent Applicant Isu9 Jidosha Co., Ltd. Representative Patent Attorney Nobuo Kinutani Figure 2 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Procedure Neichi'ilE H12 : (Voluntary) October 1985
July 29th, Director General of the Patent Office, Ubuya Michibu, 1, Indication of Case, Patent Application No. 1982-210519, 2,
Title of the invention Self-injection diesel engine combustion chamber (0
17) Izuto' Jidochu Co., Ltd. 1-6-7-5 Atago, Minato-ku, Tokyo Date of amendment order (voluntary) 1 Specification (detailed explanation of the invention) 332
Corrected as Publication No. 21 J.

Claims (5)

[Claims] (1) A sub-combustion chamber that is arranged in parallel to the main combustion chamber to communicate with each other and is recessed in the top of the piston, and a main combustion chamber that injects fuel in the direction of the swirl generated in the main combustion chamber. A fuel injection nozzle having a nozzle and a sub-nozzle that injects fuel in the direction of the swirl generated in the sub-combustion chamber when the main nozzle is closed. Injection diesel engine combustion chamber. (2) The direct injection diesel engine combustion chamber according to claim 1, wherein the auxiliary combustion chamber is formed to have a smaller volume than the main combustion chamber. (3) The main combustion chamber and the auxiliary combustion chamber are formed by being recessed in the top of the piston, and are communicated with each other by opening a part of the peripheral side wall thereof.
Direct-injection diesel engine combustion chamber according to any one of paragraphs. (4) The fuel injection nozzle is configured to open the auxiliary nozzle when the needle valve lift is below a predetermined lift, and to open the main nozzle when the lift is above a predetermined lift.
Direct-injection diesel engine combustion chamber as described in section. (5) The above patent in which the fuel injection nozzle is located in a communicating section connecting the main combustion chamber and the sub-combustion chamber, with its main nozzle facing into the main combustion chamber and its sub-nozzle facing into the sub-combustion chamber. A direct injection diesel engine combustion chamber according to claim 1 or 4.