JPS6026122A - Three-valve type internal-combustion engine - Google Patents

Abstract

PURPOSE:To give a difference to the inflow quantity of an air-fuel mixture out of each suction valve port as well as to produce a swirl of the mixture inside a combustion chamber, by making both these suction valve ports different in a bore each. CONSTITUTION:When an engine's suction stroke starts, first of all, a second suction valve opens whereby an air-fuel mixture flows much into a combustion chamber 6 from a large diametral second suction valve port 92 alone. Therefore, the inflow mixture is given a swirl in a direction toward an exhaust port 10 through the peripheral part of a spark plug 12 from the second suction valve port 92 in the light of being subject to the influence of a fact that a second branch port 132 points to a tangential direction of the peripheral wall of the combustion chamber 6. Next, a first suction valve 18, opens and therefore the air-fuel mixture flows into the combustion chamber 6 from a small diametral first suction valve port 9 as well, whereby it is joined with the mixture that has previously produced the swirl.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-valve internal combustion engine with two intake valves and one exhaust valve.

In this type of internal combustion engine, it is generally possible to obtain a sufficiently large total effective area of the intake valve ports on the ceiling surface of the narrow combustion chamber, so it is possible to increase the charging efficiency, and the effective area of each intake valve port is relatively large. The diameter of the intake valves that open and close them can be reduced to reduce their inertial weight, making it possible to improve the followability of each intake valve to the valve mechanism even when the engine is running at high speed. It has the advantage of exhibiting excellent high-speed output performance.

In such an engine, the present invention improves the mixing state of the air-fuel mixture by creating a swirl of the intake air-fuel mixture in the combustion chamber by a simple means, and promotes the start-up of combustion, thereby reducing engine load.・Stabilizes combustion even at low rotation speeds, and minimizes blow-by of the air-fuel mixture from the intake valve port to the exhaust valve port when non-polymerization occurs, allowing for effective scavenging to further improve combustion and improve fuel efficiency. The purpose is to reduce

In order to achieve this objective, the present invention is characterized in that the ceiling surface of the combustion chamber is composed of two ceiling slopes descending from a ridgeline in the approximately central part toward both sides, and a small-diameter first intake valve port is provided on one of the ceiling slopes. and a large-diameter second intake valve port are arranged in parallel along the ridgeline, and one exhaust valve port is provided on the other ceiling slope in a portion facing the first intake valve port, An ignition source is provided at a portion facing the valve port, and the first. The first valve opens and closes the second intake valve port and the exhaust valve port. This is where a second intake valve and an exhaust valve are respectively provided.

Embodiments of the present invention will be described below with reference to the drawings. First, in FIGS. 1 to 4 showing the first embodiment, the illustrated internal combustion engine is a cross-flow type four-stroke gasoline engine, and the engine body E includes a cylinder block 1 and a gasket 3 disposed on the upper surface of the cylinder block 1. 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 facing the upper surface of the piston 5, and the ceiling surface 7 of this combustion chamber 6 is formed by two ceilings that descend toward both sides at the ridge line 8 at the approximately central portion. Slope 7. ,．． 7
It consists of 2.

A pair of small-diameter first intake valve ports 9 are provided on one ceiling slope γ1.
1 and a large-diameter second intake valve port 92 are arranged and opened along the ridge line 8. At this time, the first intake valve port 91 is arranged with a larger distance to the ridgeline 8 than the second intake valve port 92 due to the smaller diameter.

On the other ceiling slope 72, one exhaust valve port 1° is opened and deviated toward the side facing the first intake valve port 9I, and furthermore, a cylinder head is provided in the portion facing the second intake valve port 92. An electrode of an ignition plug 12, which is an ignition source, is screwed onto the ignition plug 2.

The cylinder head 2 also has both intake valve ports 91.

92 and the intake boat 13 connected to the exhaust valve port 10, respectively.
and an exhaust boat 14 is formed.

The intake boat 13 has both intake valve ports 9. which are open to one end surface of the cylinder head 2. , 92, and a main line boat 13o that is divided into two parts from the downstream side of this main line boat 13o.
l +G2G2 intake taro 9I, 9□ respectively 1st. The axis of the main line port 1-1:L is the second branch port 1-131, 132, and the axis of both intake valves 9. , 92 to the first intake valve] 91 side. As a result, the second branch bow 1-13. is directed in the tangential direction of the combustion chamber 6 peripheral wall. A fuel supply device, for example, an intake pipe 15 connected to a carburetor, is connected to the upstream end of the main boat 13o.

On the other hand, the downstream end of the exhaust boat 14 opens to the other end surface of the cylinder head 2, and an exhaust pipe (not shown) is connected to the open end.

1st. Second intake valve port9. ．． 92 and the exhaust valve port 10,
Valve guide 16 to cylinder head 2. ．． The first. Second intake valve 1B,,1
82 and exhaust valve 19, and a valve mechanism AI for opening and closing these valves I L and 182 - 19 is disposed above the cylinder head 2 .

The valve mechanism M includes valve springs 207, which are connected to the valves 181, 18□, and 19, respectively, and spring the valves in the closing direction.
202.21, and the rocker arm 22s, 222.21, and the valve 1B, 182°19. 23, the valves 181, 18□, 19 are connected to the joint spring 20+
, 202. The valves 18□ and 182.19 are provided with opening/closing timings as shown in FIG. 4 by this valve operating mechanism M. .

That is, the opening timing of the first intake valve 181 is the same as that of the second intake valve 18.
2, and both intake valves 1'L,
The valve closing timings of 182 are made to coincide with each other.

In addition, the exhaust valve 19 and the first. Second intake valve 18. ．． Between each opening/closing timing of 182, a valve throat matching period t, , 22 is provided, and from the relationship with the above-mentioned valve opening timing, 62〉tI
It becomes.

Furthermore, the valve opening curves of both intake valves 1B, , 1820 are made parallel, thereby increasing the valve opening lift amount of the first intake valve 1B to the second valve opening curve.
It is smaller than that of the intake valve 182. In connection with this, the valve spring 20 of the first intake valve 181 has a small valve opening lift amount. The spring force of the valve spring 20□ is set to be weaker than that of the other valve spring 20□. If you do this, the valve spring will be 20! The valve opening torque of the camshaft 24 is reduced by the same amount, which has the effect of reducing the internal loss of power.Moreover, the difference in the size of the first and second intake valve ports 9...92 In relation to this, since the weight of the first intake valve 18- is reduced by forming the three umbrella parts smaller in diameter than the second intake valve 182, the above effect can be promoted.

Next, the operation of this embodiment will be explained.

When the intake stroke of the engine begins, the second intake valve 18□ opens, and a large amount of air-fuel mixture flows into the combustion chamber 6 through the large-diameter second intake valve port 92, so that the second branch boat 13□ As shown by the arrow in FIG. A swirl is applied in the direction toward the exhaust valve port 1o through the exhaust valve port 1o. Next, the first intake valve 181 opens, and the air-fuel mixture also flows into the combustion chamber 6 from the small-diameter first intake valve port 91, joining the air-fuel mixture that has previously swirled. In this way, the mixture state of the air-fuel mixture in the combustion chamber 6 is improved, and the air-fuel ratio is made uniform.

In addition, in the present invention, the first. Two intake valves 18I.

In some cases, the opening timings of the valves 182 and 182 may be made to coincide with each other, and even in such a case, the flow of a large amount of air-fuel mixture flowing into the large-diameter first intake valve port 9 becomes dominant, and the same mixture as described above is generated in the combustion chamber 6. It can also create a swirl of energy.

1st. At the beginning of the opening of the second intake valves is, ia2, there is a valve opening period in which the exhaust valve 19 is also still open, and the combustion chamber 6 is scavenged during this period. At this time, as described above, the first intake valve port 91 is made small in diameter to suppress the flow rate of the air-fuel mixture from the valve port 91 to a relatively small amount, and the first intake valve port 9I is connected to the second intake valve port. Separate from ridgeline 8 than 9□ (
- Since a sufficient distance to the exhaust valve port 10 is ensured, blow-by of the air-fuel mixture from the first intake valve port 91 to the exhaust valve port 10 can be suppressed to a minimum. Furthermore, the first intake valve 18 on the side closer to the exhaust valve port 10. During the non-polymerization period 11 between the exhaust valve 19 and the exhaust valve 19, the second intake valve 1 on the far side from the exhaust valve port 1o
Since the non-polymerization period t2 between 8□ and the exhaust valve 19 is set to be smaller than the non-polymerization period t2, suppression of blow-by of the air-fuel mixture from the first intake valve port 91 to the exhaust valve port 1o is facilitated.

Near the end of the compression stroke of the engine, the spark discharge from the ignition plug 12 ignites the air-fuel mixture in the combustion chamber 6 and burns it.

At this time, the air-fuel mixture ignited by the spark plug 12 is immediately carried by the swirl in the above direction to the exhaust valve 19, which is already in a high temperature state due to the influence of JJ1 air heat, so that the start of combustion is promoted. Ru.

Figure 5 shows a second example in which the present invention is applied to a torch-ignited internal combustion engine.
This shows an embodiment, and only the differences from the previous embodiment will be described.The ceiling slope 7□ on which the exhaust valve port 10 is provided has a squish in the portion facing the second intake valve port 92. A pair of torch nozzles 31 serving as ignition sources are opened at a side surface 30a of the squish portion 30 toward the side 1 intake valve port 91. A sub-combustion chamber 32 connected to the torch nozzle 31 is formed above the squish portion 30, and an electrode of a spark plug 33 screwed onto the cylinder head 2 is disposed in the chamber 32. Although not shown, the auxiliary combustion chamber 3
A sub-intake valve port is opened on the upper surface of the valve 2, and a sub-intake valve for opening and closing the valve is provided in one of the valves.

In FIG. 5, parts corresponding to those in the previous embodiment are not designated by the same reference numerals.

As described above, according to the present invention, by simply changing the diameters of the sub-intake valve ports, the amount of air-fuel mixture flowing into the combustion chamber is varied by providing a difference in the amount of air-fuel mixture flowing into the combustion chamber. Swirl can be generated, and as a result, the mixing state of the air-fuel mixture can be improved, and the combustion start-up of the air-fuel mixture can be promoted, and combustion can be stabilized even when the engine is under low load and at low rotation speed.

In addition, by forming the first intake valve port facing the exhaust valve port to have a small diameter, the amount of mixed air flowing from the intake valve port is regulated to be relatively small, so that when non-polymerization occurs, the first intake valve port It is possible to effectively scavenge the combustion chamber by suppressing the blow-through of the mixture from the air-fuel mixture to the exhaust valve port, thereby further improving combustion and reducing fuel consumption. The amount of fuel gas discharged can be reduced.

[Brief explanation of drawings]

1 to 4 show the first embodiment of the present invention,
Figure 1 is a bottom view of the cylinder head of an internal combustion engine, Figures 2 and 3 are sectional views taken along lines 11-n and -11 in Figure 1, and Figure 4 is the opening/closing timing of the intake and exhaust valves of the engine. Figure, 5th
The figure is a bottom view of a cylinder head of an internal combustion engine showing a second embodiment of the present invention. 6... Combustion chamber, 7... Ceiling surface, 71... One ceiling slope, 72... Other ceiling slope, 8... Ridge line, 9
．． ．． 92...1st. 2nd intake valve port, 10...4 no 1
Air valve port, 12... Ignition plug as an ignition source, 13...
Intake boat, 13°...Main line boat, 13°, 132
...First. Second branch boat, 31... one ignition source and l-
Torch nozzle patent applicant Honda Giichi 111 Kogyo Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of 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 small-diameter first intake valve port and a large-diameter first intake valve port. Second intake valve ports are arranged in parallel along the ridgeline, and one exhaust valve port is provided on the other ceiling slope at a portion opposite to the first intake valve port, and one exhaust valve port is provided at a portion opposite to the second intake valve port. An ignition source is provided in each of the opposing parts, and the first. The first valve opens and closes the second intake valve port and the exhaust valve port. A three-valve internal combustion engine that is provided with a second intake valve and an exhaust valve. (2. In the item described in claim (1),
A three-valve internal combustion engine, wherein the opening timing of the first intake valve is set later than that of the second intake valve. (3) In what is stated in claim (1),
Said 1st. The intake boat connected to the second intake valve port is divided into a common main line boat and the first intake boat branched from the downstream side of this main line boat. The first one leads to the second intake valve port, respectively. a second branch port, and the axis of the main boat is connected to the first branch port. Second
A three-valve internal combustion engine offset from the center position between the intake valve ports toward the first intake valve port.