JPS5996431A - Three-valve type internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the combustion capacity by shaping a ceiling face of a combustion chamber into two ceiling slopes by a ridge line approximately at the central part for providing the first and the second suction valves on one side and an exhaust valve, an ignition source and a squash part on the other side. CONSTITUTION:A ceiling face 7 of a combustion chamber 6 is composed of two ceiling slopes 71 and 72 going down to both sides from a ridge line 8 approximately in the centeral part; the first and the second suction valve ports 91 and 92 are opened in parallel on the slant face 71, and a single exhaust valve port 10 is opened on the other slant face 72 to be deviated to the opposite side of the 91. A squash part 11 is provided in an area surrounded by a circumferential brim of the combustion chamber 6 and valve ports 92 and 10, and on its side face 11a, torch nozzles 12 and 12 are opened to be approximately directed to the valve port 91. Consequently, an ignition source and the squash part can be arranged in a position where a deisred capacity can be obtained, and the sqash part can give a swirl directed toward the exhaust valve port. This construction permits to intensify the flow of air-fuel mixture and obtain a high compression ratio for improving the combustion as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-valve internal combustion engine having two intake valve ports and one exhaust valve port opening into a combustion chamber.

In this type of internal combustion engine, it is generally possible to obtain a sufficiently large total effective area of the intake valve port on the ceiling surface of the narrow combustion chamber, so that the charging efficiency can be increased. Since the effective area of each intake valve port is relatively small, the inertia weight of each intake valve is reduced by reducing the diameter of each intake valve that opens and closes, thereby improving the ability of each intake valve to follow the valve train during high-speed operation of the engine. This has the advantage of providing excellent high-speed output performance.

The present invention provides swirl and squish to the air-fuel mixture using a squish section provided on the ceiling of the combustion chamber in such an engine, and furthermore, the swirl is directed from the ignition point toward the high-temperature exhaust valve, thereby promoting combustion. The purpose is to equalize the air-fuel ratio of the air-fuel mixture in the chamber, promote the startup of combustion, and shorten the combustion time, thereby promoting the advantages described above.

An embodiment of the present invention will be described below with reference to the drawings.

The illustrated internal combustion engine is a cross-flow type 4-cycle gasoline engine, and the engine body E includes a cylinder block 1 and a cylinder head 2 which is polymerized and bonded to two surfaces of the cylinder block 1 through a gasket 3. A piston 5 is slidably fitted into a cylinder 4 formed in the cylinder block 1. A combustion chamber 6 is recessed in the bottom surface of the cylinder head 2 at a portion opposite to the top surface of the piston 5, and the ceiling surface 7 of the combustion chamber 6 has two ceiling slopes descending from a ridgeline 8 in the approximate center toward both sides. It consists of 71,7□.

One ceiling slope 7. The first pair is the first one. Second intake valve port 9
．． ．． 9. , is the ridgeline sic? '＝opened in parallel,
The other ceiling slope 72 has one exhaust valve port 10 and a first intake valve port 9. The opening is deviated toward the side facing the Furthermore, a skin section is formed in the part of the ceiling slope 72 that mainly faces the second intake valve port 92, in the illustrated example, a crescent-shaped area surrounded by the periphery of the combustion chamber 6-, the second intake valve port 92, and the exhaust valve port 10. 11 is formed, and on the side surface 11a of this squish portion 11, a pair of torch nozzles 12.12 are provided as ignition sources.
is opened substantially toward the first intake valve port 91 . The side surface 11a of the upper part 11 is inclined with respect to the direction of inflow of the air-fuel mixture from the second intake valve port 92 into the combustion chamber 6, and the air-fuel mixture flows from the second intake valve port 92 into the combustion chamber 6. First intake valve port9. It is designed to generate a swirl in the direction of .

The cylinder head 2 has an intake port 13 and an exhaust port 1.
4 is formed, and the intake port 13 has a first . The second branch port) is divided into 131.13□ and the first branch port is divided into 131.13□. Second intake valve port9. ．． 9° 5-, and its outer end opens to one side of the cylinder head 2, and an intake pipe 15 connected to a fuel supply device, for example, a carburetor C, is connected to the opening. By branching the intake port 13 within the cylinder head 2 in this manner, the passage structure of the intake pipe 15 can be simplified. On the other hand, the exhaust boat 14 has its inner end connected to the exhaust valve port 10, and its outer end opened to the other side of the cylinder head 2, and an exhaust pipe (not shown) is connected to the opening.

1st. Second intake valve port9. ．． 92 and the exhaust valve port 10,
Valve guide 16 to cylinder head 2. ．． The first. Second intake valve 18. ．． 1
82 and exhaust valve 19, and these valves 18, . 182. A valve mechanism M for opening and closing the valve 19 is disposed above the cylinder head 2.

The valve mechanism M includes valve springs 20 that are connected to the valves IL, 182, and 19, respectively, and spring the valves in the closing direction.
1,202. 21 and said valve 1'8+, 182
.

The valves 181 . 182. 19 is formed by a common camshaft 24 that can open the valves 181 . The opening/closing timing shown in FIG. 4 is given to 182°19.

That is, the opening timing of the first intake valve 18° facing the exhaust valve 19 is delayed from the opening timing of the other second intake valve 182, and the closing timings of the auxiliary intake valves 188 and 182 are made to coincide. It is. In this way, the swirl of the air-fuel mixture is strengthened during the intake stroke, and each intake valve port 9. ,9. ．． Therefore, the pulsating effect of the intake air acting on the combustion chamber 6 is not interfered with and reduced.

Further, the exhaust valve 19 and the first. Second intake valve 18. .

There is a predetermined valve polymerization period 1 between each opening and closing timing on the 1st.
1. l, is provided. In this way, backflow of exhaust gas can be minimized during low-speed operation, while scavenging can be effectively performed using exhaust inertia during high-speed operation, contributing to improved performance in both fuel efficiency and output.

Furthermore, the sub-intake valve 181. The valve opening curves of the first intake valves 18. The valve opening lift amount of the second intake valve 18□ is made smaller than that of the second intake valve 18□. In relation to this, the first intake valve 18 has a small opening lift amount. Valve spring 20. The spring force of the valve spring 202 is set to be weaker than that of the other valve spring 202. In this way, the valve spring 20. The valve opening torque of the camshaft 24 is reduced by the amount that the spring force is weakened, and the internal loss of power is reduced.

The cylinder head 2 is formed with an auxiliary combustion chamber 26 connected to the torch nozzle 12.12 on the skin part 11, and an electrode of a spark plug 25 screwed onto the cylinder head 2 faces the chamber 26.

Further, a sub-intake valve port 27 is opened on the upper surface of the chamber 26, and a sub-intake valve 29 for opening and closing the valve port 27 is provided. The auxiliary intake valve port 27 communicates with a auxiliary fuel supply device, for example, an auxiliary carburetor AC, via a auxiliary intake port 30 provided in the cylinder head 2.

The auxiliary carburetor AC generates an air-fuel mixture with a relatively rich fuel concentration, while the carburetor C generates an air-fuel mixture with a relatively lean fuel concentration.

Next, the operation of this embodiment will be explained. When the engine is operated, during the intake stroke, a rich mixture generated by the auxiliary carburetor AC is sucked into the auxiliary combustion chamber 26, and a lean mixture is sucked into the combustion chamber 6. At this time, first, the second intake valve 18□ opens (so the air-fuel mixture that flows into the combustion chamber 6 from the second intake valve port 9 is guided to the side surface 11α of the skin part 11. create a swirl, then the first
Since the intake valve 181 is opened, the air-fuel mixture flowing in through the first intake valve port 9° joins the air-fuel mixture and strengthens its swirl. As a result, the air-fuel ratio of the air-fuel mixture in the combustion chamber 6 is made uniform.

When the spark plug 25 ignites near the end of the compression stroke of the engine, the rich mixture in the auxiliary combustion chamber 26 ignites, becomes a flame, and is injected into the combustion chamber 6 from the torch nozzle 12.12.
Burn a lean mixture.

By the way, in the case of such a torch ignition type engine, it is located at a distant location, which in this embodiment corresponds to a portion a near the first intake valve 1B. Therefore, the lean air-fuel mixture ignited in the combustion chamber 6 is immediately carried by the swirl in the above direction to the vicinity of the exhaust valve 190, which is already in a high temperature state due to the influence of exhaust heat. promoted.

Furthermore, during the compression stroke of the engine, the squish surface 11b of the squish portion 11 cooperates with the upper surface of the piston 5 to provide squish to the air-fuel mixture in the combustion chamber 6, thereby increasing the compression ratio and increasing the flow of the air-fuel mixture. can be strengthened.

A pair of auxiliary torch nozzles 12a having a smaller diameter than the torch nozzle 12 are provided on the skin surface 1i/+.

12a is opened.

As described above, according to the present invention, the ceiling surface of the combustion chamber is constituted by two ceiling slopes descending from the ridgeline in the approximately central part toward both sides, and one of the ceiling slopes has a pair of first and second intake valve ports. are opened in parallel along the ridgeline, and one exhaust valve port is opened in the other ceiling slope at a position opposite to the first intake valve port,
Further, an ignition source and a squish portion are provided at a position opposite to the second intake valve port, and an ignition source and a squish portion are provided at a position opposite to the second intake valve port. The first valve opens and closes the second intake valve port and the exhaust valve port. Since a second intake valve and an exhaust valve are provided respectively, a wide area is available for the ignition source and the squish section, and these can be freely laid out to obtain the desired performance without being obstructed by the three valves. can.

Further, the skinsh portion is formed so as to give a swirl to the air-fuel mixture flowing into the combustion chamber from at least the second intake valve port in a direction from the ignition point of the ignition source toward the defecation valve port. Flow enhancement and high compression ratio are achieved, and the mixture passes around the high-temperature exhaust valve immediately after ignition, promoting the start of combustion, shortening combustion time and improving anti-nonking properties. Overall combustion is significantly improved, reducing fuel consumption and promoting high output performance.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a bottom view of the cylinder head, and FIGS.
FIG. 4 is a vertical cross-sectional view of the internal combustion engine taken along the lines 1 and 11-ITI, respectively, and FIG. 4 is a diagram showing the opening/closing timing of the intake and exhaust valves of this engine. AC... Sub-carburetor, C... Carburetor, E... Engine body, M... Valve mechanism, α... Ignition point, 2... Cylinder head, 4... Cylinder, 5...・・・
Piston, 6... Combustion chamber, 7... Ceiling surface, 71,7
□...Ceiling slope, 8...Ridge line, 9. ．． 92 mountains 1st.
Second suction. Valve port, 10...Exhaust valve port, 11...Squish portion,
12...Torch nozzle as ignition source, I L , 1
8□・・・1st. 2nd intake valve, 19...exhaust valve 13- Fig. 1 Fig. 2 M 23/ ◎ ◎ ＼, in 2°'ゝ, ゝ,', ,'7'' 75 \478 31 70β ru◎Z' 5 E/□- Figure 3

Claims (1)

[Claims] (1) The ceiling surface of the combustion chamber is composed of two ceiling slopes descending from a ridgeline in the approximate center toward both sides, and one ceiling slope has a pair of first ceiling slopes. Second intake valve ports are opened in parallel along the ridge line, one exhaust valve port is opened on the other ceiling slope at a position opposite to the first intake valve port, and the second intake valve An ignition source and a skin part are provided at a position facing the mouth, and the first
．． The first valve opens and closes the second intake valve port and the exhaust valve port.
．． A second intake valve and an exhaust valve are each provided, and the squish portion provides a swirl in the direction from the ignition point of the ignition source to the exhaust valve port at least to the air-fuel mixture flowing into the combustion chamber from the second intake valve port. A three-valve internal combustion engine. (4) A three-valve internal combustion engine according to claim (1), wherein the opening timing of the first intake valve is delayed from the opening timing of the second intake valve.