JPH09317482A - Engine intake structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the ignition performance of an ignition plug by dividing an intake port with a separation plate or partition wall into two passages one of which serves as a mixture passage and the other as an air passage to form two swirl flows in the same direction of different fuel concentrations and thus improve the fuel concentration in the center of the combustion engine and near the ignition plug. SOLUTION: A separation plate 10 is provided in an intake port 5 communicating with a combustion chamber 1 in a cylinder head 14 for dividing the inside passage thereof, to define a centripetal passage 6 and a centrifugal passage 7 with respect to the combustion chamber. An injector 15 is arranged on the side of the centripetal passage 6 and completes its fuel injection before an intake valve 4 opens, to allow only air to flow through the centrifugal passage 7. As the intake valve 4 is opened, atomized fuel 11 injected from the injector 15 causes at the same time a swirl flow 13 near the center of the combustion chamber, while a swirl flow 12 out of the air passage 7 swirls round the swirl flow 13 in the same direction. As a result, the fuel concentration near an ignition plug 3 is raised to improve its ignition performance and thus the combustion performance.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an intake structure for an engine.

[0002]

2. Description of the Related Art A conventional engine intake structure is disclosed in, for example, Japanese Utility Model Laid-Open No. 4-1669.

In a large-bore two-valve engine, the swirl has a large strength, so that the fuel that has entered the combustion chamber is caused to flow outward, and the concentration of the air-fuel mixture around the spark plug near the center of the combustion chamber becomes lean. It may cause a misfire or surge. Therefore, in this conventional example, the structure shown in FIG. 5 is used as a means for increasing the concentration of the air-fuel mixture around the plug. This is because the second intake port of a 4-valve engine is separated by a partition wall, air is introduced only from one of the separated passages in the low load region, and fuel is supplied by the injector provided in the other separated passage when the intake valve is open. Only the spark is directed toward the spark plug.

[0004]

However, in such a conventional engine intake structure, when the load is low,
Since the structure is such that the swirl is formed from only one air passage and the fuel is directly injected from the passage without air introduction toward the spark plug, the main flow of the swirl is biased to the outside of the combustion chamber and gas near the spark plug is discharged. The flow becomes smaller. Since the fuel is directly injected to the spark plug, the spark plug causes smoldering and misfire.

The present invention has been made in view of such conventional problems, and an object thereof is to provide an intake structure for an engine having improved ignitability and good combustion after ignition.

[0006]

In order to solve the above-mentioned problems, the present invention divides the intake port into two parts by a separation plate or a partition, one passage being a mixture passage, and the other passage being an air passage. . In addition, the intake port is divided vertically, the upper passage is used as the air-fuel mixture passage, the lower passage is used as the air passage, and the SCV is installed upstream of the separation plate or partition wall, and its opening is provided on the air-fuel mixture passage side. .

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.

First, the structure will be described. The cylinder head 1
4 is provided with a separation plate 10 for dividing the passage into the intake port 7 connected to the combustion chamber 1, and the combustion chamber central passage 6 and the outer passage 7
Is formed. The injector 15 is located on the side of the central side passage 6 and finishes the fuel injection before the intake valve opens. Then, only air flows in the outer side passage 7.

In the above structure, the fuel spray 11 injected by the injector 15 forms a swirl flow 13 in the vicinity of the center of the combustion chamber at the same time when the intake valve 4 is opened, and the swirl flow 12 from the air passage 7 is the swirl flow. Turn in the same direction as surrounding 13. As a result, the fuel concentration around the spark plug 3 can be increased, and good ignition can be achieved.
It can be burned in a short period of time with the help of a strong air flow after ignition.

FIG. 2 shows a second embodiment of the present invention, in which the air passage 7 formed by the separation plate 10c of FIG. 1 has a cross-sectional area gradually reduced toward the combustion chamber. . That is, according to the second embodiment, the speed difference between the two swirl flows 12 ′ and 13 ′ obtained in FIG. 1 can be increased, the combustion period after ignition can be further shortened, and combustion cycle fluctuations can be reduced. Can be suppressed.

FIG. 3 shows a third embodiment of the present invention, in which the opening 16a of the SCV 16 is provided on the air passage 7 side. According to this configuration, the main flow of high-speed air at low load is sent to the air passage and a part of the air is sent to the air-fuel mixture passage 6, and the speed difference between the two swirl flows 12 ″, 13 ″ can be further increased.

FIG. 4 shows a fourth embodiment of the present invention, in which an intake port 6 is divided into upper and lower parts by a separating plate 17 so that an upper side is an air-fuel mixture passage 6 and a lower side is an air passage 7. . An SCV 16 'having an opening on the air-fuel mixture passage 6 side is installed upstream of the separation plate.

By the way, the main flow of the air flow from the opening of the SCV 16 'enters the air-fuel mixture passage 6, the intake valve 4 opens, and at the same time, a strong atomized air-fuel mixture is formed together with the piston 18 which assists the formation of the tumble flow. The tumble flow 21 is formed and the fuel concentration near the spark plug 3 can be increased, and the ignitability is improved. Then, the tumble flow 20 by the air flow is generated so as to surround the tumble flow, and the combustion period is shortened.

[0015]

As described above, according to the present invention, the intake port of a two-valve engine is divided into two parts by a separating plate or a partition, one of which serves as an air + fuel passage and the other serves as an air passage. Since the air passage is located outside the combustion chamber, two same-direction swirl flows with different fuel concentrations are formed, and the fuel concentration near the center of the combustion chamber near the spark plug can be increased, improving ignitability. In addition, the effect is obtained that the combustion period after ignition can be shortened and the surge can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 3 is an explanatory view showing a third embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a conventional technique.

[Explanation of symbols]

 6 air-fuel mixture passage 7 air passage 8 exhaust port 9 intake manifold

Claims (5)

[Claims] 1. An intake structure for a two-valve engine, characterized in that an intake port is divided into two parts by a separating plate or a partition wall, one passage being an air-fuel mixture passage and the other passage being an air passage. 2. The intake structure for an engine according to claim 1, wherein the mixture passage is provided near the center of the combustion chamber and the air passage is provided outside the combustion chamber. 3. The intake structure for an engine according to claim 2, wherein the sectional area of the air passage is gradually reduced toward the inlet of the combustion chamber. 4. The intake structure for an engine according to claim 1, wherein the SCV is installed upstream of the separation plate or the partition, and the opening is provided on the air passage side. 5. An intake port is divided vertically, an upper passage is used as a mixture passage, a lower passage is used as an air passage, and an SCV is installed upstream of a separation plate or partition, and its opening is provided on the mixture passage side. A two-valve engine intake structure characterized by being installed in the.