JPS62170720A - Auxiliary chamber type combustion chamber - Google Patents

Abstract

PURPOSE:To improve startability at low temperature by so installing a fuel injection nozzle as to front, through a passage on a vortex auxiliary chamber and making the auxiliary nozzle hole of this nozzle front on the downstream side in the swirl direction and arranging a glow plug respectively in the vicinity of the passage and on the downstream in the swirl direction of the passage. CONSTITUTION:A fuel injection nozzle 7 is so installed as to front, through a passage 6 opened from one side of a cylinder head 1 and communicated to the upper part of a vortex auxiliary chamber 2, to the inside of a vortex auxiliary chamber 2. And an auxiliary nozzle hole 12 of a nozzle 7 is so installed as to front on the downstream of swirl S formed in the vortex auxiliary chamber 2 in the inner wall 6a of the passage 6. Likewise a main nozzle hole 11 is so installed as to front on nearly center of the vortex auxiliary chamber 2. On the other hand, the first glow plug 13a is offset to the axis core of the vortex auxiliary chamber 2 so that its heating part H1 may slightly contact with diffused fuel injected from the main nozzle hole 11. Likewise the second glow plug 13b, whose heating part H2 is arranged on the downstream in the swirl S direction of the passage 6, is projected to the inside of the vortex auxiliary chamber 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pre-chamber internal combustion engine, and in particular to an internal combustion engine that ignites fuel injected into a swirl pre-chamber at the same time as it is injected and evaporates and burns it to reduce the ignition delay. The present invention relates to a pre-chamber type combustion chamber that can be shortened, achieve low-temperature startability, and reduce Ia engine noise.

[Prior Art] In a diesel internal combustion engine, by shortening the time it takes for fuel injected into the combustion chamber to ignite, that is, the ignition delay time, engine startability is improved and engine noise is reduced. Are known.

Therefore, as an example, the present applicant has previously proposed
The subchamber type combustion chamber described in Japanese Patent No. 176932 was proposed.

This proposal is as shown in FIG.
A fuel injection nozzle 7 having main and auxiliary nozzles 11 and 12 is provided so as to face through the nozzle 7, and the auxiliary nozzle 12 of the nozzle 7 is made to face the inner wall 6a of the passage 6 and toward the downstream side in the direction of the swirl S. A glow plug a is disposed near the passage to constitute a swirl subchamber type diesel engine.

[Problems to be Solved by the Invention] As described above, the above proposal makes a part of the fuel injected from the sub-nozzle collide with the inner wall of the passage, thereby distributing atomized fuel with excellent ignition and evaporation properties around the inner wall of the passage. The remaining part is placed along the inner wall of the vortex sub-chamber along the swirl direction, and the flame of the atomized fuel combusted by the high-temperature heat from the glow plug a is propagated thereto, thereby improving ignitability, slow combustibility, and The aim is to simultaneously achieve low-temperature startability.

However, the vortex sub-chamber including the above-mentioned passage has an atmospheric temperature of 11
At extremely low temperatures of 5° C. or lower, good startability could not be fully exhibited.

In other words, during a cryogenic start, the flame energy of the injected fuel oil ignited by the glow plug cannot quickly raise the temperature of the compressed air in the vortex subchamber to a temperature at which the remainder of the fuel oil quickly evaporates. This is because, in this state, the swirl in the vortex subchamber causes misfire. Therefore, there has been a need for a pre-chamber type combustion chamber that exhibits sufficient startability even during such extremely low temperature startup and has low combustion 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 quickly control the fuel injected from the fuel injection nozzle into the vortex sub-chamber from the initial stage of injection even during cryogenic startup. Ignition J: This is intended to suppress the increase in engine VA noise due to ignition delay and to improve the low temperature startability of the engine.

[Summary of the Invention] In order to solve the above-mentioned problems, the present invention provides a fuel injection nozzle having a main and a sub-nozzle facing the vortex sub-chamber through a passage,
The sub-nozzle has a sub-nozzle facing the inner wall of the passage and downstream in the swirl direction, and glow plugs are provided near the passage and on the downstream side of the passage in the swirl direction. The atomized fuel particles that collide with the inner wall and are scattered are immediately ignited and evaporated and burned by the respective glow plugs near the passage from the beginning of the injection of the injected fuel to quickly raise the temperature of the compressed air in the vortex sub-chamber and reduce it to an extremely low temperature. The aim is to achieve quick start-up performance and quiet, slow-burning performance even at times.

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

FIG. 1 shows an example of a pre-chamber type internal combustion engine, and is a schematic vertical sectional view of a cylinder head having a swirl pre-chamber.

As shown in the figure, a vortex sub-chamber 2 is formed in the cylinder head 1, and a communication passage 5 is formed below the vortex sub-chamber 2 to connect the vortex sub-chamber 2 and the cylinder chamber 4 of the cylinder body (not shown). There is. A swirl chamber 5a is formed on the side of the auxiliary chamber 2 of the communication passage 5 to generate a swirl S along the inner wall 2a of the vortex flow auxiliary chamber 2 by the high pressure air forced into the cylinder chamber 4.

Now, the feature of the pre-chamber type combustion chamber of the present invention is that the injected fuel is instantly ignited and evaporated and combusted even during a cryogenic start, thereby shortening the ignition delay and reducing engine noise. .

Therefore, the swirl sub-chamber 2 and the fuel injection nozzle 7 and glow plugs 13a and 13b are configured as follows.

As shown in FIG. 1, above the swirl sub-chamber 2, a heat shield 8 for housing a fuel injection nozzle 7 is provided in a passage 6 that opens from one side of the cylinder head 1 and communicates with the swirl sub-chamber 2. It is housed integrally. The fuel injection nozzle 7 accommodates a needle valve 10 in a nozzle body 9 so as to be able to rise and fall freely, and the needle valve 1o connects the main nozzle 11 and the auxiliary nozzle 12 on the side of the auxiliary chamber 2 of the nozzle body 9 according to the engine load and rotation speed. The lift value is adjusted to open accordingly. That is, the sub-nozzle 12 is opened in the lift value range when the engine is operating at low speeds and low loads, and the main nozzle 11 and the sub-nozzle 12 are simultaneously opened when the lift value range is exceeded and the engine is in the medium-high speeds and medium-high load range. is configured to do so. Further, the nozzle diameter of the main nozzle 11 is set larger than that of the auxiliary nozzle 12, so that the main nozzle 11 is configured to eject fuel spray F1, and the auxiliary nozzle 12 is configured to eject atomized fuel spray F2.

The fuel injection nozzle 7 of the so-called Vintox type configured in this manner is provided facing the inside of the swirl sub-chamber 2 through the passage 6, and the sub-nozzle 12 is located on the inner wall 6a of the passage 6.
The main nozzle 11 is provided so as to face the downstream side of the swirl S generated in the vortex sub-chamber 2, and the main nozzle 11 is provided so as to face the substantially medium heat of the vortex sub-chamber 2.

Therefore, a part of the injected fuel from the sub-nozzle 12 collides with the inner wall 6a of the passage 6 and generates particles 3 in the atomized fuel particle group distributed around the inner wall 6a. 2a
A fuel film F4 is formed that flows downstream in the swirl S direction along.

Now, in this embodiment, two glow plugs 13a, 13 which can be lit freely to promote evaporation ignition of atomized fuel particle group "3" are used to improve ignitability even during cryogenic start-up.
b is arranged. The first glow plug 13a is integrally disposed in the cylinder head 1 facing the swirl sub-chamber 2, and the heating portion H1 of the glow plug 13a extends from the main nozzle 11 as shown in FIG. The passageway is offset from the axis of the swirl sub-chamber 2 without interfering with the swirl S so that its outer contour slightly contacts the injected diffusion fuel, and as shown in FIG. 6, that is, in this embodiment, the heating portion H1 extends near the passage on the side of the vortex subchamber 2. The second glow plug 13b is arranged so as to protrude into the swirl sub-chamber 2 so that the heating portion H2 of the glow plug 13b is on the downstream side of the passage 6 in the direction of the swirl S, and so as not to adversely affect the swirl S. be done. In addition, the heating part H2 has a larger heating area than the heating part H1 of the first glow plug 13a, and the fuel injection nF+ from the main nozzle 11 and the atomized fuel injection nF2 from the auxiliary nozzle 12 are in the vortex auxiliary chamber. It is arranged at a position where it will not be supercooled by the fuel film F4 flowing downstream in the swirl S direction along the inner wall 2a of No. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation of embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, during cranking by the starter in which the lift of the needle valve 10 is in an extremely low speed range, that is, at the time of starting, the lift value of the needle valve 10 is within the throttle period in which only the sub-nozzle 12 is opened. As shown in FIG. 2, the injected fuel from the sub-nozzle 12 collides with the inner wall 6a of the passage 6, forming atomized fuel particle groups F3 that scatter and spread around the inner wall 6a.

This atomized fuel particle group F3 is generated simultaneously with the first
Since the fuel is forcibly ignited by the heating of the glow plug 13a, it ignites and burns instantly. On the other hand, the remaining part of the fuel injected from the sub-nozzle 12 flows downstream in the direction of the swirl S along the inner wall 2a of the vortex sub-chamber 2 to form a fuel film F4 that evaporates on the wall surface. This film F4 is propagated with the thermal energy generated by the ignition of the atomized fuel particle group F3, and is burned while further promoting evaporation. Thereafter, the fuel film F4 is gradually burned along the swirl direction, so that slow combustion is achieved without any ignition delay, and engine noise is reduced.

This can be explained from the relationship between the mounting position of the first glow plug 13a and the mounting position of the second glow plug 13b shown by the dashed line in FIG.

That is, the distance R1 from the sub nozzle 12 to the heating part H2 of the glow plug 13b (the contact point with the particle group F3) is the distance R1 of the first glow plug 13a (the contact point with the particle group F3). The ratio R+/Ro to the distance Ro is 1/3, which means that the ignition time corresponding to the distance difference (R+ - Ro) can be shortened and smooth startability can be obtained.

Now, when starting at a cryogenic temperature, the second glow plug 13
b is also energized and becomes red hot. This second -9= red heat of the glow plug 13b is generated when the atomized fuel particle group F3 from the sub-nozzle 12 is ignited and flowed to the vicinity of the second glow plug 13b on the downstream side in the swirl S direction. , maintains the ignition combustion, and fuel film F4
is quickly evaporated to propagate the flame of the fuel particle group F3. Therefore, even during cryogenic start-up when the atmospheric temperature is below 115°C, the injected fuel oil is ignited and burned at the same time as the injection, and the first. Second glow plug 13
a.

Since the temperature of the compressed air can be rapidly raised by heating 13b, stable startability can be quickly obtained.

At medium to high rotations and medium to high loads, the fuel injected from the main nozzle 11 flows into the swirl subchamber 2 along the swirl S direction and is diffused. By lighting each or one of the glow plugs 13a and 13b, this diffused fuel is injected from the main injection port 11 and evaporated and ignited at the same time, so the ignition delay is shortened and it burns together with the film F4, This will help reduce smoke, reduce IC, and increase output.

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

(1) At extremely low temperatures, fuel oil can be ignited without any ignition delay using a glow plug when the intake air is throttled, so quietness and startability can be greatly improved.

(2) Since the glow plug is arranged in the forward direction of the swirl, the stability of ignition and combustion can be improved, and the warm-up time can be greatly shortened.

(3) Since the injected fuel does not directly cool the glow plug, the preheating ability can be fully demonstrated.

(4) Since the ignition delay can be shortened, noise can be significantly reduced during all operating loads, including when starting at extremely low temperatures, and at the same time, the generation of blue-white smoke and HC at low temperatures can be suppressed.

[Brief explanation of drawings]

Fig. 1 is a schematic vertical cross-sectional view showing a preferred embodiment of the pre-combustion chamber of the present invention, Fig. 2 is a cross-sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is a view showing a conventional example. It is. In the figure, 1 is the cylinder head, 2 is the swirl subchamber, 6 is the passage,
7 is a fuel injection nozzle, 11 is a main nozzle, 12 is a sub-nozzle, 1
3a and 3b are glow plugs.

Claims (1)

[Claims] A fuel injection nozzle having a main and a sub-nozzle is provided facing the vortex sub-chamber through a passage, and the sub-nozzle of the nozzle faces the inner wall of the passage and downstream in the swirl direction, and the vicinity of the passage and its A subchamber type combustion chamber characterized in that glow plugs are disposed on the downstream side in the swirl direction from the passage.