JPH0681900B2 - Subchamber diesel engine combustion chamber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a diesel combustion chamber, and more particularly to slow evaporation combustion of fuel oil injected into the combustion chamber even at the time of extremely low temperature starting when the atmospheric temperature becomes extremely low. The present invention relates to a diesel combustion chamber capable of reducing ignition delay and blow-up time to reduce NOx, blue and white smoke, smoke, combustion noise and irritating odor.

[Prior Art] Generally, in a diesel internal combustion engine, by shortening the time until the fuel injected into the combustion chamber is ignited, that is, the ignition delay time, the combustion peak temperature and the combustion chamber pressure sudden rise are suppressed, and combustion noise and HC are reduced. It is known that it can be greatly reduced.

Therefore, the present applicant has, as an example thereof, previously filed Japanese Patent Application No. 60-11507.
He proposed a diesel combustion chamber of No. 6 and a subchamber internal combustion engine of Japanese Patent Application No. 61-18005.

The proposal of this diesel combustion chamber is, as shown in FIG. 7, provided with a fuel injection nozzle c having a sub injection port b facing the vortex sub chamber a serving as the combustion chamber, and injected into the combustion chamber from the sub injection port b. The glow plug d is provided so as to come into contact with the base of the fuel that diffuses as a result.
As shown, main and sub nozzle hole f through passages e to swirl antechamber a _1, provided so as to face the fuel injection nozzle g with b _1, a secondary injection port b ₁ of the nozzle g of the passage e It is formed so as to face the inner wall e ₁ and the downstream side in the swirl (vortex flow) direction, and the main injection port f to face the downstream side in the swirl direction from the axis of the nozzle g.

[Problems to be Solved by the Invention] In each of the above proposals, a part of the fuel injected from the sub-injection is made to collide with the inner wall of the passage so that the atomized fuel excellent in ignition and vaporization is distributed around it. And, the rest is along the swirl direction as the fuel film along the inner wall of the vortex flow sub-chamber, and the flame of the atomized fuel is propagated to this to try to simultaneously achieve ignitability and slow combustion. In particular, the former causes a misfire during afterglow due to the supercooling of the glow plug, and the smoke and the combustion noise are greatly improved. The latter causes a thermal pinch that causes abnormal combustion by optimizing the relationship between the fuel spray and the swirl. This is intended to prevent NOx, exhaust particulates, smoke, and combustion noise to be greatly improved.

However, at the time of starting the engine or when the engine is blowing up under conditions where the atmospheric temperature and the engine cooling water temperature are extremely low, it is necessary to increase the amount of fuel corresponding to the friction of the engine and supply it. At times, it was necessary to open not only the sub nozzle but also the main nozzle. But,
When adopting a fuel injection nozzle that has a sub-injection opening that opens ahead of the main injection port, even if there are multiple main injection ports with respect to the sub-injection port, the diameter of the injection port is set extremely large. Blue-white smoke and smoke were generated due to the fuel spray from the injection port lowering the wall temperature of the vortex sub-chamber and the case where the glow plug was directly supercooled. Therefore, it is possible to increase the current value to the glow plug, but there is a problem in the durability of the glow plug. By the way, regarding the usefulness of the glow plug, even if the fuel spray from the auxiliary injection port is in the ignition state at the time of low temperature start, if the fuel spray from the main injection port enters the ignition area, the heat is absorbed by the fuel spray. It is necessary to have an afterglow function because it causes a fire.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a vortex sub-chamber and a vortex sub-chamber which communicates with the vortex sub-chamber in the cylinder head. In a combustion chamber of a sub-chamber diesel engine in which a passage is provided in a cylindrical shape in communication with the chamber and a heating portion is projected in the swirl chamber to provide a glow plug,
The heating section is made to project from the inner wall of the vortex sub-chamber near the passage and downstream of the passage in the vortex flow direction into the vortex sub-chamber, and a fuel injection nozzle having a sub injection port and two or more main injection ports is coaxially provided in the passage. The atomizing fuel spray is provided so that the atomized fuel spray can be jetted toward the inner wall of the passage on the side of the heating portion of the passage inner wall. It is set so that it can be scattered around the passage and the rest can flow downstream along the inner wall of the passage, and the direction of each main injection port is directed toward the inner wall of the vortex sub-chamber surrounding the heating part through the passage and spraying fuel respectively. In order to be able to supply the fuel sprays and to separately form fuel films that are diffused in the swirl direction into the inner wall of the swirl subchamber, and in addition, the spray portion radially outside of the fuel sprays On the way The surface of the heating portion of Ropuragu is obtained by setting so as to slightly contact.

[Operation] The atomized fuel spray injected from the sub-injection nozzle collides with the inner wall of the passage on the heating portion side of the glow plug, and a part of the atomized fuel spray is further shattered, and the rest is scattered around the passage. A fuel film flows downstream along the inner wall of the passage.

The atomized fuel spray finely crushed by the collision with the inner wall of the passage is quickly evaporated, ignited and burned by the heat of the compressed air and the heat of the assist of the glow plug. The rest of the atomized fuel spray becomes a fuel film flowing downstream, and burns without delay due to flame propagation. Further, the fuel spray injected from each main injection port is ejected through the passage into the vortex sub-chamber, and is not entrained in the vortex and forms a fuel film separately on the inner wall of the vortex sub-chamber. At this time, the spray portion on the radially outer side of the fuel spray has a weaker penetration force and a smaller particle diameter of the fuel than the mainstream portion of the spray on the radially inner side of the fuel spray. Absent. Therefore, the ignition of the fuel spray is ensured, and the evaporation and combustion of the fuel film due to the rise in the atmospheric temperature of the vortex sub-chamber are ensured.

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

FIG. 1 shows an example of a diesel combustion chamber, and is a schematic vertical cross-sectional view of a cylinder head having a swirl sub chamber.

As shown in the drawing, a vortex sub-chamber 2 is formed in the cylinder head 1, and a communication passage (injection hole) connecting the vortex sub-chamber 2 and a cylinder chamber 4 of a cylinder body (not shown) below the vortex sub-chamber 2.
5 is formed. On the side of the sub chamber 2 of the communication passage 5,
A swirl chamber 5a is formed for generating high-pressure air pushed from the cylinder chamber 4 in the swirl S along the inner wall 2a of the swirl sub chamber 2.

By the way, the feature of the diesel combustion chamber of the present invention is to shorten the ignition delay in all usage load regions, and to reduce NOx, smoke, blue and white smoke, exhaust particulates, combustion noise and irritating odor.

Therefore, the combustion injection nozzle 7 arranged in the swirl sub chamber 2 is configured as follows.

As shown in FIG. 1, above the swirl flow sub-chamber 2, a heat shield 8 having a fuel injection nozzle 7 housed in a passage 6 that opens from one side of the cylinder head 1 and communicates with the swirl flow sub-chamber 2. And the copper packing are integrally housed, and the fuel spray nozzle 7 is exposed to the swirl sub chamber 2 through the passage 6. A heating portion 15a of the glow plug 15 is disposed in the vortex sub-chamber 2 so as to project appropriately downstream of the passage 6 in the swirl direction.

As shown in FIG. 3, the fuel injection nozzle 7 has a needle valve 10 at the tip of a nozzle body 9 for accommodating the needle valve 10 in a vertically movable manner.
While forming the valve seat 9a on which the throttle part of 10 is seated,
A fuel injection chamber 9c that is axially raised from the valve seat 9a and is opened and closed by a throttle portion 9b is formed, and a sub injection port 12 is opened in the valve seat 9a, and the fuel injection chamber 9c is circumferentially spaced. Is formed and a plurality of main injection ports 11a and 11b inclined in the axial direction of the nozzle body 9 are provided (two injection ports in this embodiment). That is, the auxiliary injection port 12 is located above the throttle portion 9b, and the plurality of main injection ports 11 is located below the throttle portion 9b.
When a and b are formed and the lift of the needle valve 10 is below the specified lift value, the auxiliary injection port 12 is opened, and when the lift value is exceeded, the main injection port
Pins 11a and 11b are also of the pin-talks type configured to be opened. In addition, the diameter of the sub nozzle 12 is the main nozzle 11
Is formed pole diameter relative to injection caliber, from the sub-injection port 12 is ejected atomization fuel spray F _1, a main injection port 11a, respectively from b fuel spray F ₃ is adapted to be ejected . Therefore sub-nozzle hole 12 to obtain the penetration of a predetermined fuel spray F ₃ main nozzle hole 11a, b, a main combustion chamber 2 with respect to obtaining the reliability of the injection direction of the setting. The fuel spray F ₃ has a stronger penetration force than the atomization fuel spray F ₁ has.

The so-called pintox type fuel injection nozzle 7 configured as described above is provided so as to face the inside of the swirl sub chamber 2 through the passage 6, and the sub injection port 12 is provided on the inner wall 6a of the passage 6.
In addition, the swirl S generated in the swirl sub chamber 2 faces the downstream side, and each of the main injection ports 11a and 11b faces the downstream side of the swirl S as shown in FIG. Each main nozzle 11
The directions of a and 11b are such that the fuel is sprayed through the passage 6 to the inner wall 2a of the swirl chamber 2 between the communication passage 5 and the open end of the passage 6.
In order to be able to supply F ₃ and to separately form fuel films (fuel film) f that are diffused in the swirl direction on the inner wall 2a of the swirl sub-chamber 2, these fuel sprays F ₃ are further sprayed with F. The outer sprayed portion of ₃ is set so as to be able to slightly contact the surface of the heating portion 15a of the glow plug 15 during the spraying.

Therefore, as shown in FIGS. 1 and 2, a part of the fuel injected from the sub-injection port 12 collides and scatters on the inner wall 6a of the passage 6 to form the atomized fuel spray layer F ₂ distributed around the inner wall 6a. The remaining portion forms the fuel film f that flows downstream along the inner wall 2a of the swirl auxiliary chamber 2 in the swirl S direction.

As shown in FIG. 2 and FIG. 6, the fuel spray F ₃ from the main injection holes 11a and 11b forms the fuel film f along the inner wall 2a of the swirl auxiliary chamber 2.
To generate. Here, the number of the main injection ports 11 is set to 2 because the fuel film f is thinly and uniformly distributed on the inner wall 2a while ensuring a predetermined penetration force with respect to the vortex sub-chamber 2.
This is because a proper evaporation area can be secured for combustion and flame propagation.

The operation of the diesel combustion chamber of the present invention will be described below with reference to the accompanying drawings.

When the needle valve 10 is in the extremely constant speed range when the engine is started and when the load is light,
The needle valve 10 of the fuel injection nozzle 7, which is also shown in the figure, is operated in the lift direction according to the fuel oil pressure supplied into the nozzle body 9. At this time, simultaneously with the lift, the throttle portion 9b of the needle valve 10
Opens the auxiliary injection port 12 away from the valve seat 9a. Further, the stem portion 10a formed at the tip of the throttle portion 9b is defined to have a length 1 for closing the fuel injection chamber 9c until the needle portion 10 reaches a predetermined lift value, and as shown in FIG. A throttle period t whose amount is substantially constant is formed.

When the secondary injection port 12 is opened as shown in FIGS. 1 and 5, the atomized fuel spray F ₁ is ejected from the secondary injection port 12 toward the inner wall 6a of the passage 6 and toward the downstream side of the swirl S. Then, a part of it is collided with the inner wall 6a thereof to generate a spray layer F ₂ of atomized fuel which is further atomized and distributed in the periphery. On the other hand, the rest of the atomized fuel spray F ₁ forms a fuel film f which is made to flow downstream from the inner wall 6 a of the passage 6 along the inner wall 2 a of the swirl sub chamber 2 in the swirl S direction. Therefore, the spray layer F ₂ is instantly evaporated and burned by the high heat of the compressed air, and its flame is propagated to the vapor of the fuel film f, so that the slow combustion without ignition delay is achieved. Therefore, NOx, smoke, exhaust particulates, and HC are combusted in a low-load region including starting.

As the lift value of the needle valve 10 drops to a lift value exceeding the throttle period at the time of cryogenic start, when the engine is blown up, or when the amount of fuel is increased during medium or high load, as shown in FIG. The injection ports 11a and 11b are also opened, the injection amount of fuel oil increases, and the maximum injection is made at point M shown in FIG. In this operating area,
The fuel spray F ₃ is injected from the plurality of main injection holes 11a and 11b toward the downstream side of the swirl S from the axis of the nozzle body 9 and toward the inner wall 2a of the swirl auxiliary chamber 2. During injection, the spray part outside the fuel spray F ₃ has a weak penetration force and a small particle diameter of the fuel, so that the fuel spray of this diffusion part can be easily and reliably heated by the glow plug 15 even at low temperature start. Is ignited. Due to the heat energy generated at this time and the flame energy of the spray layer F ₂ , the temperature inside the swirl sub-chamber 2 is rapidly raised, and the evaporation of the fuel film f on the wall surface and the fuel spray F ₃ to be subsequently injected is promoted. Since most of the fuel spray F ₃ is bent along the swirling direction of the swirl S, a fuel film f flowing in the forward direction of the swirl S is generated along the inner wall 2a of the swirl chamber 2. Each of the fuel films f has an inner wall 2a
It is uniformly thin and is gradually distributed in the downstream direction.

In this way, even at the time of cryogenic start, during medium or high load,
Slow evaporative combustion that shortens the ignition delay and shortens the engine blow-up time can be achieved, so that the pressure inside the combustion chamber and the combustion peak temperature can be suppressed, which significantly reduces NOx, smoke, and combustion noise. By suppressing the above-mentioned thermal pinch, exhaust particulates, smoke, blue and white smoke and irritating odor can be reduced.

Further, regarding the HC, since it is possible to form a thin fuel film f with a large number of main nozzles as the number of main nozzles, the vaporization of the fuel is accelerated, and this is immediately burned by the flame, so that it is the same as a normal sub-chamber combustion chamber. Can be held at the value of.

[Effects of the Invention] As is clear from the above description, the diesel combustion chamber of the present invention can exhibit the following excellent effects.

(1) Blue-white smoke, smoke, and irritating odor can be reduced.

(2) The thermal pinch phenomenon can be eliminated, NOx,
Exhaust particulates and combustion noise can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a preferred embodiment of the diesel combustion chamber of the present invention, FIG. 2 is a view showing the injection direction of the main injection port as seen from the upper surface of FIG. 1, and FIG. 3 is a fuel injection nozzle. FIG. 4 is a schematic sectional view, FIG. 4 is a diagram showing a relationship between a crank angle, an injection rate and a lift amount of a needle valve, FIGS. 5 and 6 are schematic diagrams showing a combustion state of a diesel combustion chamber of the present invention, FIG. And the eighth
The figure is a schematic sectional view showing a conventional example. In the figure, 1 is a cylinder head, 2 is a swirl chamber, 6 is a passage,
7 is a fuel injection nozzle, 11a and 11b are main injection holes, 12 is a sub injection hole, 15
Is a glow plug.

Claims (2)

[Claims] 1. A vortex sub-chamber and a nozzle hole for connecting the vortex sub-chamber to the cylinder are provided in a cylinder head.
In a combustion chamber of a sub-chamber diesel engine in which a tubular passage is provided in communication with the vortex sub-chamber and a heating portion is provided in the vortex sub-chamber to provide a glow plug, the heating portion is provided near the passage and A fuel injection nozzle having a sub-injection port and two or more main injection ports is coaxially provided in the passage by projecting from the inner wall of the sub-flow chamber in the vortex flow direction downstream of the passage, and the direction of the sub-injection port is The atomized fuel spray is jetted toward the inner wall of the passage on the heating section side of the inner wall, and the atomized fuel spray is collided with the inner wall of the passage to scatter a part of the atomized fuel spray around the passage and the rest along the inner wall of the passage. So that the fuel spray can be supplied to the inner wall of the vortex sub-chamber surrounding the heating section through the passage and facing each other. Is the inner wall of the whirlpool subchamber In order to be able to separately form fuel films that are diffused in the vortex direction, and in addition, so that the radially outer spray portion of the fuel sprays may slightly contact the surface of the heating portion of the glow plug during injection. The combustion chamber of the sub-chamber type diesel engine characterized by being set. 2. The combustion chamber of a sub chamber type diesel engine according to claim 1, wherein the sub injection port is opened prior to the main injection port.