JPS61265322A - Combustion chamber of internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce the occurrence of a delay in ignition and the generation of blue white smoke and noise, by a method wherein, in a main combustion chamber and an auxiliary combustion chamber, placed in juxtaposition with each other to the top part of a piston, a fuel injection nozzle is located fronting on the combustion chambers and an ignition means is situated in the auxiliary combustion chamber. CONSTITUTION:A main combustion chamber 2 and an auxiliary combustion chamber 3, communicated with each other, are formed in juxtaposition in a way to dent a top part 1 of a piston. A fuel injection nozzle 4 is situated fronting on the combustion chambers 2 and 3, and an ignition means 15 is placed in the auxiliary combustion chamber 3. In which case, low cetane vale fuel spray, injected through the fuel injection nozzle 4 and mixed with swirl S produced and closed in the auxiliary combustion chamber 3 during low load running, is ignited by the ignition means 15 for combustion. During middle and high load running, the low cetane value fuel is self-ignited by vaporization of the wall surfaces of the combustion chambers 2 and 3 and vaporization by the swirl S. This causes excellent ignition of the low cetane fuel during low load running and enables to perform slow combustion throughout a whole load region.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a combustion chamber of an internal combustion engine, and more particularly to a combustion chamber of an internal combustion engine that can use low cetane fuel such as gasoline or alcohol as fuel.

[Prior Art] In general, direct injection diesel internal combustion tagA has advantages such as high combustion efficiency and low exhaust temperature, but on the other hand,
High explosion pressure, vibration, and noise were considered drawbacks.

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, thereby reducing the swirl. The so-called M
AN-M type engines are known.

However, since the M type engine is a type in which the injected fuel is evaporated and burned, it does not have sufficient wall evaporation capacity under conditions where the atmospheric temperature is low and the engine cooling water temperature is low. As a result, there is a lot of unburned matter (HC) in the combustion chamber.
This causes the generation of blue-white smoke. Furthermore, even when the air and water temperatures are normal, when the load is light such as when idling, the wall temperature required for fuel evaporation has not been reached, so a large amount of unburned matter (IIC) is generated and the combustion state is deteriorated. It was a factor that made things worse.

It has also been confirmed that this defect occurs even in the 1191 state where fuel is controlled and injected in a toroidal combustion chamber. The reason is that after ignition, the flame cannot propagate normally and it blows out.

In order to eliminate such drawbacks, the present applicant previously filed a patent application filed in 1983.
-210519 proposes a direct injection diesel engine combustion chamber.

As shown in FIG. 5, this proposal consists of a sub-combustion chamber 3 which is arranged in parallel to the main combustion chamber 2 so as to communicate with each other and is recessed in the piston top 1; It has a main nozzle that injects fuel facing in the direction of the swirl generated, and when the main nozzle inclines, it injects fuel into the sub-combustion chamber 3 facing in the direction of the swirl generated therein. A direct injection diesel engine combustion chamber is constructed with a fuel injection nozzle having a sub-nozzle.

More specifically, the auxiliary combustion chamber 3 is formed to have a smaller volume than the main combustion chamber 2, and each of the combustion chambers 2,
The combustion chambers 2 and 3 are formed so as to have a circular cross section with an open top, and a bank portion is formed by opening a part of the peripheral side walls of the combustion chambers 2 and 3.

The main and auxiliary combustion chambers 2.3 thus formed are provided with fuel injection nozzles of the pintocle nozzle type, for example, for supplying atomized fuel.

As shown in FIG. 4, this fuel injection nozzle 4 includes a needle valve 10 that is movable up and down in a nozzle body 7, and the needle valve 10 opens a sub-nozzle 11 formed in the nozzle body 7 when the lift is below a predetermined level. , the main injection port 13 formed in the nozzle body 7 is opened when the lift exceeds a predetermined value, and fuel is ejected from the main and sub injection ports 11 and 13.

Therefore, at low load, n1 of the fuel injection nozzle 4
The atomized fuel injected into the sub-combustion chamber 3 from the nozzle 11 is generated in the sub-combustion chamber 3, mixes with the swirl S trapped therein, and is instantly evaporated, resulting in a preheater with excellent ignitability. A mixture F is generated. On the other hand, most of the injected atomized fuel collides with the inner wall 3a of the n1 combustion chamber 3 and forms a fuel film H that flows along the inner wall 3a of the auxiliary combustion chamber 3. Since this fuel film H gradually receives heat and evaporates from the inner wall 3a of the sub-combustion chamber 3, when the premixture F is ignited and combusted,
The flame is gradually propagated to the fuel film I''. Therefore, the fuel in the sub-combustion chamber 3 is combusted while preventing the pressure in the combustion chamber from rising rapidly.

At high loads, the penetration force from the main nozzle 13 is large,
Since the fuel spray with a relatively large particle size is injected into the main combustion chamber 2, the fuel spray mixes with the swirl S generated in the main combustion chamber 2 and trapped therein, evaporates, and becomes ignitable. A good premixture F is generated. On the other hand, most of the fuel spray forms a fuel film H that collides with the inner wall 2a of the main combustion chamber 2 and flows along it.

Therefore, the premixture F is ignited and combusted by the flame generated in the auxiliary combustion chamber 3, and this flame is gradually propagated to the fuel film H that is evaporated by the inner wall 2a of the main combustion chamber 2, and the premixture F is ignited and combusted by the flame generated in the auxiliary combustion chamber 3. Slow combustion within the combustion chamber 2 will be achieved.

[Problem to be solved by the invention 1 The direct injection diesel engine combustion chamber configured as described above achieves slow and quiet combustion over a wide range of low-load and high-load operations. It is designed to suppress the occurrence of

However, when the atmospheric temperature is low, the entire engine is cooled, so that the combustion chamber cannot have sufficient evaporation capacity at the time of startup. Therefore, the present applicant inserted a glow plug into the auxiliary combustion chamber to assist the spontaneous ignition of the auxiliary combustion chamber. However, this glow plug cannot demonstrate sufficient ability to ignite unless the cetane number of the supplied fuel is above a certain level; for example, pure alcohol.

This was not sufficient to apply to low cetane number fuels such as gasoline.

[Object of the invention].

The present invention was created to solve the above problems, and
The purpose of the invention is to reduce gasoline during low loads.

To provide a combustion chamber for an internal combustion engine that can satisfactorily ignite a low cetane number fuel such as pure alcohol, perform slow combustion over the entire load range, and reduce blue-white smoke and noise.

[Summary of the Invention] In order to achieve the above object, the present invention includes a main combustion chamber and a sub-combustion chamber that communicate with each other by recessing the top of the piston, and injecting fuel into each combustion chamber. A fuel injection nozzle is provided, and an ignition means for igniting the fuel is provided in the sub-combustion chamber. At low load, low cetane is generated in the sub-combustion chamber and mixed with the swirl trapped therein. The fuel spray is ignited and combusted by the above-mentioned ignition means, and when the load is medium or high, the fuel is spontaneously ignited by evaporation on the wall of each combustion chamber and evaporation by swirl, thereby greatly reducing ignition delay, blue-white smoke, and noise. It is something to do.

[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:
The main combustion chamber 2 and the sub-combustion chamber 3 are recessed from this and are each formed to have, for example, a circular cross-sectional shape with an open top. In addition, the main combustion chamber 2 and the sub-combustion chamber 3 are
Mutual peripheral side walls 2a.

A bank portion 16 is formed by opening a part of 3a.

The volume ratio of the auxiliary combustion chamber 3 and the main combustion chamber 2 is such that the main combustion chamber 2 has a larger volume than the auxiliary combustion chamber 3, and specifically, the circular cross section of the upper main combustion chamber 2 is larger than that of the auxiliary combustion chamber 3. The auxiliary combustion chamber 3 is formed to have a larger diameter than the circular cross section, and is recessed shallower than the main combustion chamber 2.

The main combustion chamber 2 formed in this way and the 11 combustion chamber 3
As shown in FIG. 4, a fuel injection nozzle 4 is provided in the bank portion 16 so as to face it, and this fuel injection nozzle 4 is attached to a cylinder head (not shown). 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; It is opened from the seat 8 and the iN
A secondary combustion chamber is formed on the inner wall 3a of the J combustion chamber 3, as shown in FIG. The injection port 11 is opened at the inner end of the nozzle body 7 and along the axial direction of the needle valve 10, and accommodates the reduced diameter portion 12 of the needle valve 10, and when opened, the fuel is discharged. As shown in FIG. 1, it is formed from a main nozzle 13 provided on the inner wall 2a of the main combustion chamber 2 to inject downstream in the direction of the swirl S generated therein.

Further, the sub-nozzle 11 and the main nozzle 13 are each opened between the lifts of the needle valve 10, and when the engine is under low load, the sub-nozzle 11 is opened at a predetermined lift or less.
is opened, and above that lift, the main nozzle 13 is opened and the fuel required for high-load operation is combusted! ! 2.3
supplied within.

Now, in the embodiment of the present invention, the fuel injection nozzle 4
When the fuel injected from the engine is a low cetane number fuel such as gasoline or pure alcohol, an ignition means 15 is provided in order to reliably ignite and burn the fuel in low-temperature atmosphere under low load.

As shown in FIG. 1, the ignition means 15 is provided so as to hang down facing into the auxiliary combustion chamber 3, and for example, a spark plug or the like is used.

Hereinafter, the operation of the present invention will be explained based on the accompanying drawings.

As shown in FIGS. 1 to 4, swirl S supplied from a swirl boat (not shown) is generated and confined within the main and sub-combustion chambers 2.3, respectively, while being compressed.

Therefore, when the engine is started or under low load, a low cetane number fuel spray is injected from the sub-nozzle 11 of the fuel injection nozzle 4 into the sub-combustion chamber 3. The fuel spray collides with the inner wall 3a of the auxiliary combustion chamber 3, becomes further atomized, and forms a fuel film H that flows along the inner wall 3a.

Here, a part of the ejected low cetane number fuel has a small particle size and is instantly evaporated by the swirl to generate a premixture F that is easily ignited and combusted, and the remainder is generated in the fuel film H. After that, the wall surface evaporates.

Therefore, by causing the premixture F to be ignited by the ignition means 15, the premixture F is ignited and burned. Due to this ignition, the flame spreads to the auxiliary combustion chamber 3.
The fuel film F is propagated from the ignition position in the auxiliary combustion chamber 3 toward the inner wall 3a and flows along the inner wall 3a.
It will burn gradually. In addition, when starting at a low temperature, by adjusting the air-fuel ratio of the fuel, the ignition means 1
It is possible to control the ignitability of the fuel for 5 ignition.

In this way, the spray from the sub-nozzle 3 is sprayed onto the inner wall 3 of the sub-combustion chamber 3.
a, so much 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 the swirl S in the sub-combustion chamber 3
Most of the combustion gas is trapped within the sub-combustion chamber 3 and combustion within the sub-combustion chamber 3 is achieved, thereby increasing the combustion temperature and suppressing the generation of blue-white smoke and unburned matter (IIc). become. For this reason, at low loads,
The average combustion temperature in the sub-combustion chamber 3 increases, and as a result, the generation of blue-white smoke and the generation of unburned matter (IIc) can be suppressed.

Furthermore, under high load, the fuel spray from the main nozzle 13 is directed toward the inner wall 2a of the main combustion chamber 2 and toward the downstream direction of the swirl S. As shown in FIG. 2, fuel is injected to produce a fuel film H and a premixture F in the same manner as described above. At this time, part of the combustion gas in the auxiliary combustion chamber 3 causes flame propagation to 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 n1 nozzle 11 and has a greater penetration force, so the premixture F generated by mixing the evaporated fuel and the swirl S Since the fuel does not generate excessive amount of fuel, even if it ignites, rapid combustion will not 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 premix F, and this vapor is combusted and is slowly burned. This suppresses the pressure rise inside the system, further reducing noise. In addition, the higher the load, the more the fuel injected from the main nozzle 13 is layered, and at most 90% or more of the fuel is injected, so the above effect is reliably achieved, and the flame flowing from the auxiliary combustion chamber 3 reliably It will be ignited.

[Effects of the Invention] As detailed above, according to the present invention, the following excellent effects are exhibited.

(1) The main combustion chamber and the sub-combustion chamber are arranged side by side at the top of the piston, and a combustion chamber is formed in which they communicate with each other.The ignition means is provided in the sub-combustion chamber, so that the engine can be started at a low temperature. It can reliably ignite and burn low cetane number fuels such as light oil, pure alcohol, and gasoline under low load conditions. can be reduced.

cV Since the connecting part that communicates with the main combustion chamber and the sub-combustion chamber is provided, a part of the combustion gas in the sub-combustion chamber enters the main combustion chamber, and the combustion gas is injected into the main combustion chamber and evaporated, The premixture and fuel film are ignited and burned quickly and! Since slow combustion can be achieved, noise can be prevented over a wide range from low loads to high loads.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a preferred practical example of the present invention, FIG. 2 is a schematic sectional view showing the injection direction of a fuel injection nozzle that injects fuel into a main combustion chamber and a sub-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 cross-sectional view of the fuel injection nozzle shown in FIG. 2, and FIG. 1 is a diagram showing a conventional example. In the figure, 1 is the top of the piston, 2 is the main combustion chamber, 3 is the sub-combustion chamber, 4 is the fuel injection nozzle, 11 is the sub-nozzle, 13 is the main nozzle,
15 is an ignition means.

Claims (5)

[Claims] (1) A main combustion chamber and a sub-combustion chamber are provided side by side by recessing the top of the piston and communicating with each other, and a fuel injection nozzle for injecting fuel is provided in each combustion chamber, and an ignition means is provided in the sub-combustion chamber. A combustion chamber of an internal combustion engine characterized by: (2) The combustion chamber of the internal combustion engine according to claim 1, wherein the auxiliary combustion chamber is formed to have a smaller volume than the main combustion chamber. (3) The fuel injection nozzle is located in a bank connecting the main combustion chamber and the auxiliary combustion chamber, and has its main nozzle facing into the main combustion chamber and its auxiliary nozzle facing into the auxiliary combustion chamber. A combustion chamber for an internal combustion engine according to claim 1 or 2. (4) The fuel injection nozzle is configured to open the auxiliary nozzle to eject atomized fuel when the needle valve has a predetermined lift or less, and open the main nozzle to eject fuel spray when the needle valve has a predetermined lift or more. A combustion chamber for an internal combustion engine according to claim 3. (5) The combustion chamber of an internal combustion engine according to any one of claims 1 to 4, wherein the ignition means is comprised of a spark plug.