JPH0673335U - Sub-chamber diesel engine - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the mixing efficiency of the main combustion chamber of the piston and improve the smoke and particulates in a sub-chamber diesel engine. [Structure] A main combustion chamber 17 is recessed at the top of the piston 16. The outer side portions are overlapped with each other to form a first swirl chamber 3 and a second swirl chamber 4 in the cylinder head 2, and a communication portion 5 for communicating the first swirl chamber 3 and the second swirl chamber 4 with each other. To form. On the lower surface 6 of the cylinder head that isolates the swirl chambers 3 and 4 from the cylinder 7, the cylinder 7 and the first
A first injection hole 8 and a second injection hole 9 are provided to connect the swirl chamber 3 and the cylinder 7 to the second swirl chamber 4, respectively. The first injection hole 8 and the second injection hole 9 are merged at a position near the cylinder 7,
The first swirl chamber 3 and the second swirl chamber 4 are attached to the cylinder head 2.
Fuel injection nozzle 15 to supply fuel spray to only one side
To provide.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sub-chamber diesel engine, and more particularly to a sub-chamber diesel engine formed by connecting two swirl chambers in a cylinder head.

[0002]

[Prior art]

 In general, diesel engines are of the type that directly supplies fuel spray to the main combustion chamber (main chamber) that is recessed in the piston (direct injection diesel engine), and fuel is supplied to the swirl chamber formed in the cylinder head. A spray is supplied to cause pre-combustion in the swirl chamber, and a pre-combustion gas in the swirl chamber (a semi-combustion gas consisting of combustion flame and mixture) is injected into the main combustion chamber of the piston ( There is a type (sub-chamber diesel engine) in which the fuel is supplied through a connection port) and combustion is completed here.

Among these, the sub-chamber diesel engine is capable of uniformly diffusing the fuel spray into the swirl chamber having a small volume, and further dispersing a rich premixed mixture (meaning a mixture having good ignitability). Since it is possible to obtain rapid combustion with high heat generation rate and extremely low HC, it is possible to diffuse-burn the pre-combustion gas in the main combustion chamber of the piston, which can reduce NOx. It has advantages and is widely adopted as a low-pollution diesel engine.

[0004]

[Problems to be solved by the device]

 However, even in the conventional sub-chamber diesel engine, there was a problem that the pre-combustion gas and the combustion air were not sufficiently mixed in the main combustion chamber of the piston, and there was still a large amount of smoke and particulates. .

An object of the present invention is to provide a sub-chamber diesel engine that emits significantly less particulates and smoke.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a main combustion chamber recessed at the top of a piston, a first swirl chamber and a second swirl chamber formed in a cylinder head by superposing outer portions thereof on top of each other. The cylinder, the first swirl chamber, the second swirl chamber, the communication part formed by superimposing the second swirl chamber and the cylinder, the first swirl chamber, the second cylinder on the lower surface of the cylinder head that separates the first swirl chamber and the second swirl chamber from the cylinder. In a sub-chamber diesel engine having a first injection hole and a second injection hole provided so as to communicate with the swirl chamber, a cylinder-side opening end of the first injection hole and the second injection hole is located near the cylinder. And a fuel injection nozzle is provided in the cylinder head to supply the fuel spray to only one of the first swirl chamber and the second swirl chamber.

[0007]

[Action]

 When entering the compression stroke, the compressed air in the cylinder flows into the first swirl chamber and the second swirl chamber from the first injection hole and the second injection hole, respectively, as the pressure in the cylinder rises. The compressed air flowing into the first swirl chamber through the first injection hole generates a swirl in the first swirl chamber, and the compressed air flowing in from the second injection hole into the second swirl chamber generates a swirl flow in the second swirl chamber. Let

At the end of the compression stroke, the fuel spray is supplied from the fuel injection nozzle to only one of the first swirl chamber and the second swirl chamber. Here, for convenience, the swirl chamber that receives the supply of the fuel spray is referred to as a first swirl chamber. The fuel spray supplied to the first swirl chamber is agitated by the swirl flow in the first swirl chamber and evaporated by the thermal energy of the high temperature atmosphere to be premixed and vaporized, and burned rapidly. At this time, the pressure due to combustion is evenly applied to the second swirl chamber via the communicating portion. Therefore, when the pre-combustion gas is ejected from the first injection hole into the cylinder, the combustion air is also ejected from the second injection hole into the cylinder, so that the pre-combustion gas and the second swirl chamber are discharged. This combustion air merges with each other on the cylinder side, mixes with each other, is ejected into the cylinder, and is further mixed with air in the main combustion chamber of the piston.

[0009]

【Example】

 A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a side sectional view of a sub-chamber diesel engine according to the present invention. As shown in the figure, the sub-chamber 1 is composed of a first swirl chamber 3 and a second swirl chamber 4 which are formed in the cylinder head 2 by superposing their outer parts on top of each other. The swirl chamber 3 and the second swirl chamber 4 are formed by overlapping each other. The volumes of the first swirl chamber 3 and the second swirl chamber 4 are set to be substantially the same, and the total volume of the first swirl chamber 3 and the second swirl chamber 4 is one swirl chamber and one main combustion chamber. It is specified to be the same as the volume of the swirl chamber of a conventional sub-chamber diesel engine equipped with a chamber.

On the lower surface 6 of the cylinder head, the cylinder 7 and the first vortex chamber 3 are separated from the cylinder 7 and the first vortex chamber 3 and the second vortex chamber 4, respectively. 4 are communicated with each other, and a first injection hole 8 and a second injection hole 9 are provided.

The cylinder-side opening end 18 of the first injection hole 8 faces the outer peripheral side of the main combustion chamber 17, and the cylinder-side opening end 10 of the second injection hole 9 corresponds to the first injection hole 8 of the first injection hole 8. It communicates with the opening end 18 on the cylinder side. The first swirl chamber side opening end 11 of the first injection hole 8 is tangentially faced to the inner wall 12 of the first swirl chamber 3 so as to generate a swirl V1 around the horizontal axis in the first swirl chamber 3, and the second swirl chamber 2 is ejected. The second swirl chamber side opening end 13 of the hole 9 is tangentially faced to the inner wall 14 of the second swirl chamber 4 in order to generate a swirl V2 around the horizontal axis in the second swirl chamber 4. In addition, the first injection hole 8 and the second injection hole 9 can generate the vortex flow V1 and the vortex flow V2, respectively, in the first vortex flow chamber 3 and the second vortex flow chamber 4 with appropriate throttling loss, and having a small throttling loss. It is set for each caliber.

The fuel injection nozzle 15 is attached to a portion of the cylinder head 2 which defines and forms the first swirl chamber 3 so as to supply the fuel spray F only to the first swirl chamber 3.

As described above, in the present embodiment, the cylinder-side opening end portion 18 of the first injection hole 8 and the cylinder-side opening end portion 10 of the second injection hole 8 are provided at the position of the first injection hole 8 close to the cylinder 7. And the fuel injection nozzle 15 is attached so as to supply the fuel spray F only to the first swirl chamber 3, so that in the compression stroke, the first swirl chamber 8 through the first swirl chamber 8 3 and the second swirl chamber 4 for injecting combustion air, and in the combustion stroke, the pre-combustion gas is ejected from the first injection hole 8 toward the main combustion chamber 17 and at the same time for combustion from the second injection hole 9. It is configured to eject air toward the main combustion chamber 17 of the piston 16.

Next, the operation of this embodiment will be described.

As shown in FIG. 1, when the compression stroke is started, the compressed air in the cylinder 7 flows from the first injection hole 8 and the second injection hole 9 as the pressure in the cylinder 7 rises. And the second vortex chamber 4. The compressed air that has flowed into the first swirl chamber 3 through the first injection hole 8 generates a swirl V1 in the first swirl chamber 3 as shown in FIG. The compressed air flowing into the chamber 4 generates a vortex flow V 2 in the same rotation direction as the vortex flow V 1. Therefore, there is no shearing of air at the location where the vortex V1 and the vortex V2 are in contact with each other, and there is no reduction in vortex strength due to mutual interference between the vortex V1 and the vortex V2.

As shown in FIG. 1, when the fuel spray F is injected from the fuel injection nozzle 15 to the first swirl chamber 3 at the end of the compression stroke, the fuel spray F injected from the first injection hole 8 is swirled. The mechanical agitation by V1 and the high-temperature atmosphere in the first swirl chamber 3 promotes evaporation, which is mixed with combustion air to be premixed and vaporized, and uniformly dispersed in the first swirl chamber 3. In the present embodiment, the concentration of the premixed gas is considerably high because the volume of the first swirl chamber 3 is almost half that of the conventional swirl chamber, so that the premixed mixture reaches the spontaneous combustion temperature. When it burns, it has a much higher heat release rate and combustion pressure than before, and HC is greatly reduced compared to the previous case.

At this time, since the combustion pressure is propagated from the first swirl chamber 3 to the second swirl chamber 4 due to the existence of the communicating portion 5, the pressures of the first swirl chamber 3 and the second swirl chamber 4 become equal. Therefore, as shown in FIG. 3, during the diffusion combustion period in which combustion occurs in the second swirl chamber 4 and the pre-combustion gas is supplied from the first injection holes 8 to the main combustion chamber 17, it is stored in the second swirl chamber 4. The combustion air that has been discharged is ejected from the second injection hole 9 toward the confluence portion 19 of the cylinder-side opening end portion 18 of the first injection hole 8 and the cylinder-side opening end portion 10 of the second injection hole 9 at once. It will be. Therefore, the pre-combustion gas is first mixed with the combustion air in the second swirl chamber 4 at the confluence portion 19 of the first injection hole 8 and the second injection hole 9, and is further mixed in the main combustion chamber 17 with the main air. It is secondarily mixed with the combustion air in the combustion chamber 17. Therefore, mechanical agitation with a strong mixed gas of pre-combustion gas and combustion air eliminates the problem of low mixing performance between pre-combustion gas and combustion air, which has been a problem in the past. Oxidative combustion of particulates is significantly improved, and smoke, particulates and Nox are greatly reduced.

In the prior art relating to the sub-chamber type diesel engine, the first swirl chamber and the second swirl chamber are formed by superimposing the outer side portions on top of each other in the cylinder head. It was obtained by overlapping the first swirl chamber and the second swirl chamber by connecting both swirl chambers and the inside of the cylinder to form a nozzle hole (communication port) on the lower surface of the cylinder head that isolates the chamber from the cylinder. A bank-shaped partitioning unit has been proposed in which a vortex with no damping can be generated in each of the first vortex chamber and the second vortex chamber (Japanese Utility Model Laid-Open No. 4-82323), but this proposal is The second swirl chamber is used as it is for the combustion chamber as it is, and the combustion air stored in the second swirl chamber 4 is used as the combustion pressure in the first swirl chamber 3 as shown in this embodiment. Is ejected from the second injection hole 9 using the Immediately before entering the main combustion chamber 17, the combustion air from the hole 9 is mixed with the pre-combustion gas which is about to enter the main combustion chamber 17 from the first injection hole 8, and the pre-combustion gas and the combustion air are mixed with each other. It wasn't something I tried to improve. Therefore, the configuration of this proposal cannot significantly reduce smoke and particulates.

[0020]

[Effect of device]

 As is clear from the above description, the present invention produces the following excellent effects.

(1) Since the pre-combustion gas and the combustion air are mixed both before entering the main combustion chamber of the piston and when entering the main combustion chamber, oxidative combustion of smoke and particulates is prevented. It can be significantly accelerated.

(2) Smoke and particulates can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a preferred embodiment of a sub-chamber diesel engine according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

[Explanation of symbols]

 2 Cylinder head 3 1st swirl chamber 4 2nd swirl chamber 5 Communication part 7 Cylinder 8 1st injection hole 9 2nd injection hole 10 Cylinder side opening end 15 Fuel injection nozzle 18 Cylinder side opening end

Claims (1)

[Scope of utility model registration request] 1. A main combustion chamber recessed at the top of the piston,
A first swirl chamber and a second swirl chamber are formed in the cylinder head by superposing the outer side portions on top of each other, a communication portion formed by superimposing the first swirl chamber and the second swirl chamber, and A first nozzle hole and a second nozzle hole provided on the lower surface of the cylinder head separating the first swirl chamber and the second swirl chamber so as to communicate the cylinder with the first swirl chamber and the cylinder with the second swirl chamber.
In a sub-chamber diesel engine having an injection hole, the cylinder-side opening ends of the first injection hole and the second injection hole are merged at a position closer to the cylinder, and the first swirl chamber and the second swirl flow in the cylinder head. A sub-chamber diesel engine, characterized in that a fuel injection nozzle is provided to supply fuel spray to only one of the chambers.