JPS6361710A - Stratified combustion engine - Google Patents

Abstract

PURPOSE:To improve ignitionability and reduce fuel consumption sharply by providing a fuel injection valve in an intake passage near an intake valve, and a squish area inside a combustion chamber. CONSTITUTION:A fuel injection valve 20 to injectedly supply fuel into a combustion chamber 5 is provided near an intake valve 8 on the side of the intake port 6 of a cylinder head 4. A projected part 23 is formed on a part opposite to the inner wall periphery of a cylinder bore 2a on the top of a piston 3, and a squish area 22 on the inner wall periphery of the cylinder bore 2a opposite to the direction of fuel injection from the fuel injection valve 20. Thus the radial stratification of a mixture can improve ignitionability, and consequently the practicable lean burning operation of an engine can reduce fuel consumption sharply.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stratified combustion engine that stratifies the air-fuel mixture, and more specifically, it relates to a stratified combustion engine that stratifies the air-fuel mixture. This relates to a stratified combustion engine that enables stratification. (Refer to Japanese Unexamined Patent Publication No. 56-148636) Various attempts have been made to stratify the air-fuel mixture, but currently, fuel is injected in the latter half of the intake stroke. The most common method was to create stratification.

Mitsukoshi (88%?) Problems that Sugi is trying to solve However,
When stratifying the air-fuel mixture by injecting fuel in the latter half of the intake stroke, stratification in the vertical direction is possible to some extent, but in the radial direction, the fuel swirls around the cylinder bore. It becomes difficult to increase the mixture concentration in the center of the cylinder bore, and when the injection force is strong, the mixture concentration near the inner wall of the cylinder bore facing the fuel injection valve becomes excessive. Good stratification could not be achieved.

An object of the present invention is to provide a stratified combustion engine capable of stratifying an air-fuel mixture in the radial direction so that the air-fuel mixture concentration near the center of a cylinder bore is high. be.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection valve that injects fuel in a plane substantially perpendicular to the axis of a combustion chamber in an intake passage near the intake valve, and to at least control the fuel injection direction of the fuel injection valve. This is achieved by providing a squish area on the inner surface of the combustion chamber with opposing staggers.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic vertical cross-sectional view of a cylinder head showing the structure of the vicinity of the combustion chamber of an engine according to an embodiment of the present invention, and FIG. 2 is a drawing showing the structure of the intake and fuel injection parts thereof. .

In FIG. 1, an engine 1 includes a cylinder bore 2a formed in a cylinder block 2, an upper surface of a piston 3 fitted into the cylinder bore 2a, and a lower surface of a cylinder head 4 mounted above the cylinder block 2. The cylinder head 4 has an intake port 6 that communicates with the combustion chamber 5 from one side 4a, and an exhaust port 7 (a second port that communicates with the combustion chamber 5 from the other side 4b).
Not shown in the figure. ) is provided.

The cylinder head 4 is provided with an intake valve 8 and an exhaust valve 9 that open and close the openings of the intake boat 6 and the exhaust port 7 to the combustion chamber 5. Valve mechanism 10 that opens and closes valve 9
is provided.

In addition, the cylinder head 4 has a side section on the exhaust port 7 side.
A plug insertion hole 11 leading from three sides to the central top of the combustion chamber 5
An ignition plug 12a is mounted in the plug insertion hole 11, and an ignition part 12b at the tip thereof protrudes to the center top of the combustion chamber 5.

On the other hand, an intake manifold 13 and an exhaust manifold 14 are connected to both side surfaces 4a and 4b of the cylinder head 4, respectively, and an intake passage 15 that guides the intake air to the combustion chamber 5 causes IJ1 gas generated in the combustion chamber 5 to be transferred to the outside. Exhaust passages 16 leading to are provided respectively. The intake passage 15 is branched downstream into two, a primary intake passage 17 with a small passage cross-sectional area and a secondary intake passage 18 with a large passage cross-sectional area, and an opening of the intake boat 6 to the combustion chamber 5. The primary intake passage 17 and the secondary intake passage 18 are configured to merge at a position immediately upstream. The primary intake passage 17 supplies intake air to the combustion chamber 5 in all operating ranges of the engine 1 from low load to high load. A control valve 19 is provided that closes and opens at high load, and only when the engine 1 is under high load.
The intake air is controlled to be supplied to the combustion chamber 5 from the secondary intake passage 18 . Here, the primary intake passage 17 is
The intake flow from the primary intake passage 17 is branched downward from the intake passage 15 of the intake manifold 13 and opens at the opening surface of the intake boat 6 to the combustion chamber 5 in the second flow position. Compared to the intake air flow from the intake passage 18, it has more horizontal velocity components.

Further, a combustion chamber 5 is located near the intake valve 8 in the primary intake passage 17 at the lower side of the cylinder head 4 on the intake boat 6 side.
A fuel injection valve 20 is provided to inject and supply fuel to. That is, on the side of the primary intake passage 17 of the cylinder head 4, in a plane substantially perpendicular to the central axis of the cylinder bore,
A fuel injection valve mounting hole 21 is formed near the confluence of the primary intake passage 17 and the secondary intake passage 18, and the fuel injection valve 20 is mounted in the fuel injection valve mounting hole 21.

Therefore, fuel is injected from the fuel injection valve 20 into a plane substantially perpendicular to the central axis of the cylinder bore 2a of the combustion chamber 5.

In addition, a convex portion of the top of the piston 3 facing the inner wall of the cylinder bore 2a facing the fuel injection direction of the fuel injection valve 20 is provided so that a squish area 22 is formed around the inner wall of the cylinder bore 2a facing the fuel injection direction of the fuel injection valve 20. A shaped portion 23 is formed.

The operation of the stratified combustion engine according to the embodiment of the present invention configured as described above is as follows.

First, when the engine 1 is under low load, the control valve 19 in the secondary intake passage 18 is closed, and intake air is passed only from the primary intake passage 17, through the opening of the intake boat 6, and into the combustion chamber 1. supplied within. In this case, since the primary intake passage 17 has a small passage cross-sectional area, the intake flow velocity is high despite the low load and small intake air amount, and the primary intake passage 17
is opened and closed in a substantially tangential direction with respect to the combustion chamber 5, so that a swirl 8 as shown in FIG. 2 is formed in the combustion chamber 5 by the intake air from the primary intake passage 17. It turns out. Therefore, if no measures are taken,
The air-fuel mixture around the inner wall of the cylinder bore 2a tends to become too rich, making it impossible to collect the rich air-fuel mixture near the spark plug 12a at the center of the cylinder bore 2a, making it impossible to achieve desirable stratification. In the example, swirl A sweeps the air-fuel mixture into areas where it is likely to become overrich;
, area 22 are provided, so at the end of the compression stroke,
The rich mixture is sent to the spark plug 12 in the center of the cylinder bore 2a.
It becomes possible to collect the mixture near a, and the air-fuel mixture can be preferably stratified in the radial direction.

Furthermore, in this embodiment, the fuel is supplied to the cylinder bore 2a.
Since the fuel is injected in a plane substantially perpendicular to the central axis of the cylinder, the rich air-fuel mixture can be collected in the upper part of the cylinder bore 2a, and the air-fuel mixture can also be preferably stratified in the vertical direction of the cylinder bore 2a. Become.

Also, during high load, the control valve 1 in the primary intake passage 18
9 opens, intake air is supplied into the combustion chamber 5 from both the primary intake passage 17 and the secondary intake passage 18, and a large amount of intake air necessary to obtain the required output is supplied to the combustion chamber 5. can be supplied within Furthermore, when the load is high, air is also taken in from the secondary intake passage 18, so the swirl A that is formed is weak, so the swirl A hardly inhibits stratification in the radial direction; Since the fuel is injected in a plane substantially perpendicular to the central axis of the cylinder bore 2a, a rich air-fuel mixture is collected in the upper part of the cylinder bore 2a, and the air-fuel mixture is preferable in the vertical direction of the cylinder bore 2a. It becomes possible to convert into

FIG. 3 shows another configuration example of the fuel injection valve 20 used in another embodiment of the present invention. In this embodiment, since the fuel injection valve 20 is provided near the intake valve 8 in the primary and secondary intake roads 17, there is a large risk that the fuel injection valve 20 will be thermally damaged by blowback due to combustion. Heat also tends to cause hepatitis. However, when the fuel injection valve 20 is provided near the intake valve 8 in the primary intake passage 17, it is not possible to provide a cooling water passage near the fuel injection valve 20 in order to cool the fuel injection valve 20. , compositionally,
It is extremely difficult. Therefore, in FIG. 3, the fuel injection valve 20 is connected to the cylinder head 4 via an air assist adapter 24, and a part of the intake air (fresh air) is transferred to the air assist adapter 24. - It is configured to be sent to the adapter 24 and flowed into the chamber 25 in the air assist adapter 24, and cools the fuel injection valve 20 to suppress the generation of heber and to cool the fuel injection valve 20.
prevents damage. In addition, by supplying a portion of the intake air to the fuel injection valve 20 in this way, vaporization and atomization of the fuel injected from the fuel injection valve 20 through foaming are promoted.

The present invention is not limited to the above-mentioned examples, but various modifications can be made within the scope of the invention described in the claims, and these are also included within the scope of the present invention. It goes without saying.

For example, in the embodiment, skin area 2
Although the top of the piston 3 corresponding to the portion where the squish area 22 is to be formed is formed in a convex shape, the method of forming the squish area 22 is not particularly limited, and any known method can be used. The squish area 22 may be formed by forming the corresponding portions of 4 into a convex shape.

Further, in the above embodiment, the squish area 22 is formed only around the inner wall of the cylinder bore 2a facing the fuel injection direction of the fuel injection valve 20, but the injected fuel is formed near the center of the cylinder bore 2a. Squish areas can also be formed in other parts around the inner wall of the cylinder bore 2a so that the squish areas gather together.

According to the present invention, the air-fuel mixture can be stratified in the radial direction so that the air-fuel mixture concentration near the center of the cylinder bore is high, which improves ignitability. This enables lean-burn operation and significantly reduces fuel consumption.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of a cylinder head showing the structure of the vicinity of the combustion chamber of an engine according to an embodiment of the present invention, and FIG. It is a F side view. FIG. 3 is a drawing showing another configuration example of the fuel injection valve 20 used in another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Engine, 2... Cylinder block, 2a... Cylinder bore, 3... Piston, 4... Cylinder head, 4a, 4b... Side part of cylinder head, 5... Combustion chamber , 6... Intake boat, 7... Exhaust boat,
8... Intake valve, 9... Exhaust valve, 10... Valve mechanism, 11... Plug insertion hole, 12a... Spark plug, 12b... Ignition part, 13... Intake manifold , 14... Exhaust manifold, 15... Intake passage, 16... Exhaust passage, 17.
...Primary intake passage, 18...Second intake passage, 19...Control valve, 20...Fuel injection valve, 21...
- Fuel injection valve intake hole, 22... Squish area, 23... Convex portion on top of piston 3, 24... Air assist adapter, 25... Chamber.

Claims (1)

[Claims] A fuel injection valve that injects fuel in a plane substantially perpendicular to the axis of the combustion chamber is provided in the intake passage near the intake valve, and at least a squish area is provided on the inner surface of the combustion chamber facing the fuel injection direction of the fuel injection valve. A stratified combustion engine characterized by being equipped with.