JPS59136515A - Three-valve type internal-combustion engine - Google Patents

Abstract

PURPOSE:To raise the combustion efficiency of an internal-combustion engine having one exhaust valve and two intake valves, by producing swirl of intake air effectively by forming a branch intake port communicated with one of the two intake valves to opening a combustion chamber substantially in the tangential direction of the circumference of the combustion chamber. CONSTITUTION:In a three-valve type internal combustion engine of this invention, a first and a second intake-valve openings 91, 92 are formed in one (71) of two inclined surfaces 71, 72 constituting the top surface 7 of a combustion chamber 6 formed in the bottom surface of a cylinder head 2, while an exhaust-valve opening 10 is formed in the other inclined surface 72 at a position facing the first intake-valve opening 91. Here, an intake port 12 is constituted by a main port 12m, the inlet of which is opened in the outer surface of the cylinder head 2, and a first and a second branch ports 121, 122 branched from the main port 12m and connected respectively to the intake-valve openings 91, 92. In such an arrangement, the main port 12m is located with some displacement toward the first intake-valve opening 91 from the middle point between the two intake-valve openings 91 and 92 so that the second branch port 122 is directed substantially in the tangential direction of the circumference of the combustion chamber 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-valve internal combustion engine, and more specifically, the ceiling surface of a combustion chamber formed in a cylinder head is composed of two slopes descending from a ridgeline at a substantially central portion toward both sides, A pair of first rows on one slope. Second intake valve ports are opened in parallel along the ridgeline, and one exhaust valve port is opened on the other slope facing the first intake valve port and facing the second intake valve port. and an ignition source is provided, and the first ignition source is provided. The first valve opens and closes the second intake valve port and the exhaust valve port. This invention relates to a device provided with a second intake valve and an exhaust valve.

In this type of internal combustion engine, the total effective area of the intake valve port can generally be made much smaller than the effective area of the exhaust valve port on the ceiling surface of the narrow combustion chamber, so it is possible to increase the charging efficiency, and moreover, it is possible to Since the effective area of each intake valve port is relatively small, the diameter of the intake valve that opens and closes it is reduced to reduce its inertial weight, and the ability of each intake valve to follow the valve train during high-speed engine operation is improved. Therefore, it has the advantage of being able to exhibit excellent high-speed output performance.

The present invention aims to equalize the air-fuel ratio of the air-fuel mixture in the combustion chamber in such an engine by creating a swirl without increasing intake resistance when the air-fuel mixture flows into the combustion chamber. The purpose is to promote the rise of combustion from t% of the mixture so that the swirl takes the direction from the ignition source to the exhaust valve, thereby promoting the above-mentioned advantages and reducing fuel consumption. The intake port is characterized by a main port whose inlet opens on the outer surface of the cylinder head, and first and second branch ports that are split into two from the main port and lead to the first and second intake valve ports, respectively. and the main port is offset from the center between the first and second intake valve ports toward the first intake valve port so that the second branch port is oriented in a substantially tangential direction of the periphery of the combustion chamber. It is located where it was placed.

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

First, the internal combustion engine shown in FIGS. 1 to 3 is a cross-flow type four-stroke gasoline engine, and the engine body E includes a cylinder block 1 and a cylinder head that is polymerized and bonded to the upper surface of the cylinder block 1 through a gasket 3. 2, and 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 top surface of the piston 5.
The ceiling surface 7 has two slopes descending from a ridgeline 8 in the approximate center toward both sides. ．． It consists of 72.

- ten thousand slopes 7. The first pair is the first one. Second intake valve port9. ．．
92 are opened in parallel on the ridge line 8, and the other slope 7
2 has one exhaust valve port 10 connected to the first intake port 9. The electrode of the ignition plug 11, which is an ignition source screwed onto the cylinder head 2, is opened offset to the opposite side and is connected to the second intake valve port 9□0.
placed on opposite sides.

The cylinder head 2 has an intake port 12 and an exhaust port 1.
4 is formed, and the intake port 12 includes a main port 12m that opens an inlet on the outer surface of the cylinder head 2, and a main port 12m that is divided into two parts, the first and second ports.
The main port 12m is composed of first and second branch ports 12□ and 12□ leading to the intake valve ports 9+ and 92, respectively. 9. Both intake valves are oriented so that they are oriented. ,9
It is arranged offset from the center between the intake valves 2 and 2 toward the first intake valve port 91 side. An intake pipe 13 connected to a carburetor or other fuel supply device is connected to this main port 12771.

On the other hand, the exhaust port 14 is connected to the exhaust valve port 10, and its outlet opens on the other side of the cylinder head 2, and an exhaust pipe (not shown) is connected to the opening.

1st. The second intake valve ports 9□, 92 and the exhaust valve port 10 are connected to the cylinder head 2 with a valve guide 15. ．． 15□.

The first. Second intake valve 1
7. ．． 172 and exhaust valve 18, and these valves IL, 172
．． A valve mechanism 19 for opening and closing 18 is disposed above the cylinder head 2 .

The valve mechanism 19 includes the valve 17. , 17□ and 18, respectively, and springs them in the closing direction.
．． 20□, 21, and the valve 17. , 172°18 to Ronca arm 22. , 222, 23, respectively, said valves 17. ．． , 17□ , 18 to each valve spring 20
+, 20□, and a common camshaft 24 that can open against the elastic force of 21, and this valve operating mechanism 19 causes the valves 17. , 17□.

18 is given opening/closing timing as shown in FIG.

That is, the opening timing of the first intake valve 17° facing the exhaust valve 18 is delayed relative to the opening timing of the other second intake valve 17□, and both intake valves 17. , 17□ are made to close at the same time. Furthermore, the exhaust valve 18 and the first. Second intake valve 17. ．．
There is a predetermined non-polymerization period 1 between each opening/closing timing of 17□.
, 12 are provided.

Next, the operation of this embodiment will be explained. During the intake stroke of the engine,
When the second intake valve 172 is opened first, the air-fuel mixture supplied from the intake pipe 13 side flows into the combustion chamber 6 from the second intake valve port 9□ via the main cylinder 2m and the second branch boat 12□. At this time, since the second branch port 12□ is oriented in the substantially tangential direction of the periphery of the combustion chamber 6 as described above, the incoming mixture flows along the inner circumferential wall of the cylinder 4 as shown by the arrow in FIG. A swirl as shown in FIG. Then, when the first intake valve 171 opens, the air-fuel mixture flows into the first branch port 12. It also flows into the combustion chamber 6 through the first intake valve port 92 and joins the swirl.

As a result, the air-fuel ratio of the air-fuel mixture in the combustion chamber 6 is made uniform, and good combustion of the air-fuel mixture can be obtained even during low-load operation. Note that even if both intake valves 1γ, . . . , 172 are opened at the same time, the second
A swirl similar to that described above can be caused by the inflow mixture from the branch boat 122, but as described above, the first intake valve 17. It is effective to strengthen the swirl by delaying the opening timing of the second intake valve 122 from that of the second intake valve 122.

Further, as described above, the mixture flow takes a swirl direction from the second intake valve port 9□ to the ignition plug 11 and the exhaust valve 18, so that immediately after being ignited at the ignition plug 11, it is already in a high temperature state due to the influence of exhaust heat. Since the mixture passes through the vicinity of the exhaust valve 18, which is located at Since the swirling path of air is relatively long, the first phase during valve polymerization. The second intake valve ports 91 and 92 can also prevent the air-fuel mixture from blowing into the exhaust valve port 10 as much as possible, thereby reducing the amount of unburned components discharged.

Furthermore, as mentioned above, the non-polymerization period 1. , 12, the exhaust inertia is effectively utilized to open both intake valve ports 9.
, 92 can also draw the air-fuel mixture into the combustion chamber 6, resulting in a good scavenging effect.

Furthermore, since the closing timings of both the intake valves 171 and 172 coincide, the pulsating effect of the intake air acting on the combustion chamber 6 from each intake valve port 91-92 is not attenuated by interference.

Further, in the illustrated example, the opening curves of both intake valves 17□ and 172 are made substantially parallel, thereby making the opening lift amount of the first intake valve 17□ smaller than that of the second intake valve 172. In relation to this, the first intake valve 1 with a small valve opening lift amount
7□ 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 opening torque of the camshaft 24 is reduced by the amount that the spring force of the valve spring 201 is weakened, so that the internal loss of power is reduced.

FIG. 5 shows an embodiment in which the present invention is applied to a four-cylinder internal combustion engine. In all cylinders, the first intake valve port 9□ is located on the outer end side of the cylinder head 2, and the second intake valve port 92 is located on the outer end side of the cylinder head 2. The main ports 12m of all the intake ports 12 are placed closer to the center of the cylinder head 2.

This is advantageous because the intake manifold attached to the cylinder head 2 and distributing the air-fuel mixture to each intake port 12 can be made smaller. In FIG. 5, the same components as in the previous embodiment are given the same reference numerals.

As described above, according to the present invention, the main port has an inlet opening on the outer surface of the cylinder head, and the first and second branches that are separated from the main port and lead to the first and second intake valve ports, respectively. The main port is moved from the center between the first and second intake valve ports toward the first intake valve port so that the second branch port is oriented in a substantially tangential direction of the periphery of the combustion chamber. Because it is arranged offset, it is possible to create an intake resistance at the intake port, and the swirl takes the direction from the ignition source to the exhaust valve. This, together with the swirl effect, promotes the start-up of combustion, shortens the combustion time, improves anti-knocking properties, and significantly improves combustion as a whole, promoting high output performance and reducing fuel consumption. be achieved.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention,
Figure 1 is a bottom view of the cylinder head, Figures 2 and 3 are longitudinal sectional views of the internal combustion engine taken along the lines ■-■ and Ill-Ill in Figure 1, respectively, and Figure 4 is the intake and exhaust of this engine. FIG. 5 is a diagram showing the opening and closing timing of the valve, and is a bottom view of a cylinder head showing a second embodiment of the present invention. 1° cylinder block, 2pa cylinder head, 6.
... Combustion chamber, 7... Ceiling surface, 7□, 72... Slope, 8... Ridgeline, 91.9° - 1st. a second intake valve port;
10・Exhaust valve port, 11...Ignition plug as an ignition source, 1
2...Intake port, 12m...Main port, 124,12
□・・・First. Second intake valve, 18...exhaust valve Fig. 1'/2'/7 1-~ and m= Fig. 3 1.9 Fig. 2 9

Claims (1)

[Claims] (1) The ceiling surface of the combustion chamber formed in the cylinder head is composed of two slopes descending from a ridgeline in the approximate center toward both sides, and one slope has a pair of first slopes. Second intake valve ports are opened in parallel along the ridge line, and the first intake valve port is opened on the other slope.
one exhaust valve port is opened opposite to the intake valve port, and an ignition source is disposed opposite to the second intake valve port;
The second intake valve port and the first valve port that opens and closes these to the exhaust valve port.
．． In a three-valve internal combustion engine provided with a second intake valve and an exhaust valve, the main port has an inlet opening on the outer surface of the cylinder head; first and second leading to the intake valve port, respectively;
The branch port and the intake port are configured such that the second branch port is oriented in a substantially tangential direction of the periphery of the combustion chamber,
A three-valve internal combustion engine, wherein the main port is arranged offset from the center between the first and second intake valve ports toward the first intake valve port. (2. In the item described in claim (1),
A three-valve internal combustion engine, wherein the opening timing of the first intake valve is delayed from that of the second intake valve.