JPH0540269Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a pre-chamber internal combustion engine, and in particular to a pre-chamber combustion engine that shortens ignition delay, improves low-temperature startability, and reduces engine noise. Regarding the room.

[Prior Art] In a diesel internal combustion engine, the time it takes for fuel injected into the combustion chamber to ignite, that is, the ignition delay time, is shortened, which improves engine startability and reduces engine noise. This is generally known.

For this reason, the present applicant had previously proposed a swirl subchamber type diesel engine as described in Japanese Patent Application No. 58-193477.

This proposal is based on the vortex subchamber 2 as shown in Figure 5.
A fuel injection nozzle 7 having main and auxiliary nozzles 11 and 12 is provided facing through the passage 6, and the auxiliary nozzle 12, which is opened in advance of the main nozzle 11, is provided on the inner wall of the passage 6. 6a, and facing the downstream side in the swirl S direction, constitutes a swirl sub-chamber type diesel engine.

[Problems to be solved by the invention] As mentioned 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. let me,
Moreover, 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 is propagated thereto, thereby achieving ignitability and slow combustion at the same time.

However, when the wall surface temperature of the entire vortex sub-chamber including the passage does not reach a temperature sufficient to evaporate the injected fuel, i.e., when starting at a low temperature, or when the initial evaporation capacity does not follow the amount of injected fuel, i.e., when the engine During rapid acceleration, the above-mentioned ignition delay still occurs, causing noise.

Therefore, it is desired to make the atomized fuel distributed in the passageway more easily ignited and evaporated to shorten the ignition delay and improve noise reduction and startability.

[Purpose of the invention] The present invention was devised to solve the above problems.The purpose of the present invention is to ignite the fuel injected from the fuel injection nozzle into the vortex subchamber from the initial stage of injection. This aims to suppress the increase in engine noise due to delays and improve engine startability.

[Summary of the invention] In order to solve the above-mentioned problems, the present invention provides a fuel injection nozzle having a main and auxiliary nozzle through a passage in the vortex auxiliary chamber, and a auxiliary nozzle of the nozzle is arranged on the inner wall of the passage. In addition, it faces the downstream side in the swirl direction, and is recessed in the shape of a groove along the swirl direction in the wall of the sub-chamber upstream in the swirl direction from the nozzle, and the end portion on the downstream side in the swirl direction is An air guide groove with an open end is formed in the passage, and by introducing compressed air flow from the guide groove into the passage, turbulent flow is generated in the passage, and this turbulence and the above-mentioned secondary air flow are generated. By mixing the atomized fuel oil that collides and scatters from the nozzle with the inner wall of the passage, the injected fuel is instantly evaporated and ignited, and the fire is ignited by the injected fuel from the auxiliary nozzle flowing along the inner wall of the vortex sub-chamber. This is intended to spread to the rest of the engine and simultaneously improve engine startability and quiet, slow combustion.

[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 pre-chamber type internal combustion engine, and is a schematic longitudinal 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 with a cylinder chamber 4 of a cylinder body (not shown). There is. On the side of the sub-chamber 2 of the communication passage 5, there is a swirl chamber 5a for generating the high-pressure air pushed in from the cylinder chamber 4 into a swirl S along the inner wall 2a of the swirl sub-chamber 2.
is formed.

The pre-chamber type combustion chamber of the present invention is characterized by good mixing of injected fuel and air during low-temperature starts, low engine speeds and low loads, shortening ignition delay, and reducing engine noise. The goal is to reduce

Therefore, the swirl subchamber 2, the fuel injection nozzle 7, and the air guide groove 13 are configured as follows.

As shown in FIG. 1, above the vortex subchamber 2,
A heat shield 8 accommodating a fuel injection nozzle 7 is integrally housed in a passage 6 that opens from one side of the cylinder head 1 and communicates with the swirl sub-chamber 2 . The fuel injection nozzle 7 accommodates a needle valve 10 in a nozzle body 9 so as to be able to move up and down, and the needle valve 10 is connected to a main nozzle 11 and a sub-nozzle 1 on the sub-chamber 2 side of the nozzle body 9.
The lift value is adjusted to open 2 and 2 according to the engine load and rotation speed. In other words, low engine speed
The sub-nozzle 12 is opened in the lift value range during low-load operation, and the main nozzle 11 and the sub-nozzle 12 are simultaneously opened in the mid-high rotation/medium-high load range of the engine exceeding the lift value range. . Also, main nozzle 1
The diameter of the nozzle nozzle 1 is set larger than that of the sub nozzle 12.

The so-called pintokes-type fuel injection nozzle 7 configured in this way is provided facing the inside of the swirl sub-chamber 2 through the passage 6, and is provided facing the inside of the vortex sub-chamber 2 through the passage 6.
2 faces the inner wall 6a of the passage 6 and on the downstream side of the swirl S generated in the vortex subchamber 2, and the main nozzle 11 is provided facing approximately the center of the vortex subchamber 2.

Therefore, a part of the fuel injected from the sub-nozzle 12 is
It collides with the inner wall 6a of the passage 6 and scatters to generate atomized fuel particle group _F1 distributed around it, and the remaining part is
A fuel film _F2 is formed that flows downstream in the swirl S direction along the inner wall 2a of the swirl subchamber 2.

Now, in this embodiment, in order to improve ignitability, an air guide groove 13 is provided to generate the atomized fuel particle group _F1 and to promote evaporation and ignition of the atomized fuel particle group _F1 . It will be done. This air guide groove 13 is formed in the shape of a groove on the inner wall 2a of the swirl subchamber 2 upstream of the fuel injection nozzle 7 in the swirl S direction, as shown in FIGS. 1 to 3. It is formed by recessing and opening the downstream end in the swirl S direction into the communication passage 5. In this embodiment, the swirl subchamber 2
The side communication passage 5 and the passage 6 are connected by the air guide groove 13.

Therefore, compressed air is supplied from the cylinder chamber 4 into the swirl sub-chamber 2 to generate a swirl S, and at the same time, as shown in FIG. turbulent flow R is generated. This turbulent flow R causes the atomized fuel particle group _F1 to be agitated, thereby producing an active air-fuel mixture with excellent ignition and evaporation properties.

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

As shown in FIG. 1, when the engine is running at low speed and under low load, compressed air is forced from the cylinder chamber 4 through the communication passage 5 into the vortex subchamber 2, where a strong swirl S is generated. At this time, the compressed air flow A is forced into the passage 6 by the air guide groove 13, and a turbulent flow R is generated therein.

On the other hand, the fuel injected from the sub-nozzle 12 is as shown in FIG.
As shown in FIG. 2, a group of atomized fuel particles collide with the inner wall 6a of the passage 6 and scatter and spread around the inner wall 6a.
F ₁ is formed, and this atomized fuel particle group F ₁ is stirred under the influence of the turbulent flow R, thereby promoting mixed evaporation and instantaneously igniting and burning. 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 and evaporates on the wall surface, producing a fuel film _F2 . This film F ₂ is propagated with thermal energy due to the ignition of the atomized fuel particle group F ₁ and is burned while further promoting evaporation. Then the above fuel film
Since _F2 is gradually combusted along the swirl direction, it achieves slow combustion without ignition delay and reduces engine noise.

At medium to high speeds and medium to high loads, as shown in FIG. 4, the injected fuel from the main nozzle 11 flows into the swirl subchamber 2 along the swirl S direction and is diffused. This diffused fuel _F3 is influenced by the turbulent flow R and the compressed air flow A, and is efficiently mixed with the compressed air to improve the air-fuel ratio, so it burns together with the film _F2 , reducing smoke. , which will help reduce HC and increase output.

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

(1) Since the ignition delay can be shortened, noise can be significantly reduced, and at the same time, the generation of blue-white smoke and HC at low temperatures can be suppressed.

(2) It is possible to improve the combustibility of fuel, reduce smoke and increase output.

[Brief explanation of the drawing]

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 detailed view of the main part of Fig. 1, and Fig. 3 is a cross-sectional view taken along the - line in Fig. 1. Figure, 4th
The figure shows the combustion state of the pre-chamber type combustion chamber of the present invention.
FIG. 5 is a diagram showing a conventional example. In the figure, 1 is the cylinder head, 2 is the swirl subchamber, and 6 is the cylinder head.
is a passage, 7 is a fuel injection nozzle, 11 is a main injection port, 1
2 is a sub-nozzle, and 13 is an air guide groove.

Claims (1)

[Scope of utility model registration request] 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 is located upstream of the nozzle in the swirl direction. An air guide groove is formed in the side wall of the sub-chamber along the swirl direction, and the downstream end of the air guide groove is opened into the passage. Pre-chamber type combustion chamber.