JPH0120295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-valve multi-cylinder internal combustion engine in which two intake valve ports and one exhaust valve port are opened into each combustion chamber.

This type of internal combustion engine is conventionally known as shown in Japanese Unexamined Patent Publication No. 56-23518, and generally the total effective area of the intake valve port is made larger than the effective area of the exhaust valve port on the ceiling surface of the narrow combustion chamber. Since the effective area of each intake valve port is relatively small, the diameter of the intake valve that opens and closes it can be reduced to reduce its inertial weight, and the engine This has the advantage that the followability of each intake valve to the valve train during high-speed operation can be improved, and excellent high-speed output performance can therefore be exhibited.

The present invention aims to equalize the air-fuel ratio of the air-fuel mixture in the combustion chamber by generating swirl without increasing intake resistance when the air-fuel mixture flows into the combustion chamber, and furthermore, the swirl The air-fuel mixture takes a relatively long swirling path from the ignition source to the exhaust valve, thereby promoting the rise of combustion of the air-fuel mixture and suppressing blow-by of the air-fuel mixture from the intake valve port to the exhaust valve port during valve polymerization. It is an object of the present invention to provide a three-valve multi-cylinder internal combustion engine that promotes the above-mentioned advantages, reduces fuel consumption and exhaust emissions, and also contributes to downsizing of the intake manifold. shall be.

In order to achieve this object, the present invention forms a plurality of combustion chambers lined up along the axis of the crankshaft in the cylinder head, and extends the ceiling surface of each combustion chamber into a substantially central portion extending parallel to the axis. A pair of first and second intake valve ports are opened in parallel along the ridge line on one slope, and the first and second intake valve ports are opened on the other slope in parallel with each other along the ridge line.
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 first and second intake valve ports and the exhaust valve port; First and second intake valves and exhaust valves are provided for opening and closing these, and the cylinder head has a main port having an inlet opening on one side of the cylinder head in a direction perpendicular to the axis, and a main port having an inlet opening on one side of the cylinder head in a direction perpendicular to the axis. The intake port is composed of a first and second branch port that is divided into two ports and leads to the first and second intake valve ports, respectively, and an outlet that is connected to the exhaust valve port and that is connected to the axis of the cylinder head. An exhaust port opening on the other side in a direction orthogonal to the combustion chamber is formed corresponding to each combustion chamber, and the second branch port is oriented in a substantially tangential direction of the periphery of the combustion chamber,
the main port is arranged offset from the center between the first and second intake valve ports toward the first intake valve port;
Furthermore, in each of the outermost combustion chambers, the first intake valve port is arranged closer to the center of the cylinder head than the second intake valve port.

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

The internal combustion engine shown in Figures 1 to 4 is a cross-flow type 4 engine.
It is a cycle four-cylinder gasoline engine, and the engine body E includes a cylinder block 1 and a cylinder head 2 which is polymerized and bonded to the upper surface of the cylinder block 1 through a gasket 3. A plurality of cylinders 4 are formed in parallel in the direction along the axis (not shown), and a piston 5 is slidably fitted into each cylinder 4.

A combustion chamber 6 is recessed in the bottom surface of the cylinder head 2 at a portion facing the top surface of each piston 5, and the ceiling surface 7 of each combustion chamber 6 extends from a ridgeline 8 at approximately the center extending parallel to the crankshaft axis. It consists of two slopes 7 ₁ and 7 ₂ that go down on both sides.

On one slope 7 ₁ , a pair of first and second intake valve ports 9 ₁ and 9 ₂ are opened in parallel along the ridge line 8, and on the other slope 7 ₂ , one exhaust valve port is opened. 10 is deviated and opened to the side opposite to the first intake valve port ₉₁ ,
Further, an electrode of an ignition plug 11 serving as an ignition source screwed onto the cylinder head 2 is disposed on the opposite side of the second intake valve port ₉₂ .

An intake port 12 and an exhaust port 14 are formed in the cylinder head 2.
is a main port 1 having an inlet opening on one side of the cylinder head 2 in a direction perpendicular to the crankshaft axis;
2m, and first and second branch ports 12 1 and 12 2 that are divided into two from this main port 12m and reach the first and second intake valve ports _{9 1} and _{9 2 ,} respectively. 12 m is offset from the center between the intake valve ports 9 ₁ and 9 ₂ toward the first intake valve port 9 ₁ so that the second branch port 12 ₂ is oriented in a substantially tangential direction of the periphery of the combustion chamber 6. Placed.
Each branch pipe 13 of the intake manifold is connected to each main port 12m. Therefore, in each combustion chamber 6, the first intake valve port ₉₁ is larger than the second intake valve port ₉₂ ,
In addition, the exhaust valve ports 10 are arranged closer to the center of the cylinder head 2 than the electrodes of the spark plugs 11 serving as ignition sources, thereby directing the main ports 12m of the intake ports 12 corresponding to the outermost combustion chambers 6 to the cylinder head. 2, the intake manifold to which the outermost branch pipe 13 is connected to the main port 12m can be downsized in the crankshaft direction.

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 in the direction orthogonal to the crankshaft axis, and each opening of the exhaust port 14 is connected to the exhaust valve port 10. Branch pipes are connected.

First and second intake valve ports 9 ₁ , 9 ₂ and exhaust valve port 1
0 has valve guides 15 ₁ , 15 in the cylinder head 2.
_The first and second intake valves 17 1 , 17 ₂ and the exhaust valve 18 are slidably supported via valves ₂ and 16 to open and close the valves 17 ₁ and 17 ₂ , respectively. , 18 is disposed above the cylinder head 2. The valve mechanism 19 includes the valves 17 ₁ , 17 ₂ , 18
valve springs 20 ₁ , 20 2 , 21 which are respectively connected to the valve springs 20 1 , 20 ₂ , 21 and spring the _springs in the closing direction;
7 ₂ , 18 with Rotzker arms 22 ₁ , 22 ₂ , 22
The valves 17 ₁ , 17
₂ and 18 are connected to a common camshaft 24 that can open the valves 17 1 and 18 against the elastic force of the respective valve springs 20 ₁ , 20 ₂ , and ₂₁ .
17 ₂ and 18 are given opening/closing timings as shown in FIG.

That is, the first intake valve 17 ₁ facing the exhaust valve 18
The opening timing of the second intake valve 17 ₂ is delayed with respect to the opening timing of the other second intake valve 17 2 , and both intake valves 17 ₁ , 17 ₂
The valve closing timings are made to match. Furthermore, the exhaust valve 18
Predetermined valve overlapping engines _l 1 and l ₂ are provided between the opening and closing timings of the first and second intake valves 17 ₁ and 17 ₂ .

Next, the operation of this embodiment will be explained. During the engine's intake stroke, when the second intake valve ₁₇₂ is first opened,
Air-fuel mixture supplied from the intake pipe 13 side is connected to main port 1
2m and the second branch port ₁₂₂ , and flows into the combustion chamber 6 from the second intake valve port ₉₂ , but at this time, the second
Since the branch port ₁₂₂ is oriented in the substantially tangential direction of the periphery of the combustion chamber 6 as described above, the incoming air-fuel mixture flows along the inner circumferential wall of the cylinder 4 and forms a swirl as shown by the arrow in FIG. That is, the engine rotates from the second intake valve port 9 ₂ toward the spark plug 11 and the exhaust valve 18 . Next, when the first intake valve 17 ₁ opens, the air-fuel mixture also flows into the combustion chamber 6 from the first intake valve port 9 ₁ via the first branch port 12 ₁ 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. Incidentally, even if both the intake valves 17 ₁ and 17 ₂ are opened at the same time, the same swirl as described above can be caused by the air-fuel mixture flowing in from the second branch port 12 ₂ . If the opening timing of the intake valve 17 ₁ is delayed from that of the second intake valve 12 ₂ , it is more effective to strengthen the swirl.

Further, the air mixture flow is controlled by the second intake valve port 9 as described above.
By taking a swirl direction from ₂ to the ignition plug 11 and the exhaust valve 18, immediately after the ignition plug 11 ignites, the fuel passes around the exhaust valve 18, which is already in a high temperature state due to the influence of exhaust heat. Therefore, the rise of combustion is promoted together with the swirl effect, and in particular, the second intake valve port _{92 is provided on one slope 71 of} the ceiling slope 7, and the exhaust valve port ₁₀ is provided on the other slope 72. By opening the second intake valve port ₉₂ and the exhaust valve port 10, it is possible to separate the second intake valve port 92 and the exhaust valve port 10 from each other as much as possible in the crankshaft direction.
From the second intake valve port 9 ₂ through the ignition source to the exhaust valve port 10
The swirling path of the air-fuel mixture toward
Blow-by of the air-fuel mixture from the first and second intake valve ports 9 ₁ and 9 ₂ to the exhaust valve port 10 during valve polymerization can be prevented as much as possible, and the amount of unburned components discharged can be reduced.

Furthermore, since the valve polymerization engines l ₁ and l ₂ are provided as described above, the air-fuel mixture can be drawn into the combustion chamber 6 from both the intake valve ports 9 ₁ and 9 ₂ by effectively utilizing the exhaust inertia. , a good scavenging effect can be obtained. Furthermore, since the closing timings of both the intake valves 17 ₁ and 17 ₂ coincide, the pulsating effect of the intake air acting on the combustion chamber 6 from the respective intake valve ports 9 ₁ and 9 ₂ is not attenuated by interference.

In addition, in the illustrated example, the opening curves of both intake valves 17 ₁ and 17 ₂ are made substantially parallel, so that the first intake valve 1
The valve opening lift amount of 7 ₁ is made smaller than that of the second intake valve 17 ₂ . In connection with this, the valve spring 20 ₁ of the first intake valve 17 ₁ having a small valve opening lift amount is set to have a weaker spring force than the other valve spring 20 ₂ . 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.
Internal loss of power is reduced.

As described above, according to the present invention, a plurality of combustion chambers arranged along the axis of the crankshaft are formed in the cylinder head, and the ceiling surface of each combustion chamber is arranged at a substantially central portion extending parallel to the axis. Consisting of two slopes descending from the ridgeline to both sides, a pair of first and second intake valve ports are opened in parallel along the ridgeline on one slope, and the first intake valve is opened on the other slope. an ignition source is provided opposite the second intake valve port, and an ignition source is provided opposite the second intake valve port, and these are provided at the first and second intake valve ports as well as the exhaust valve port. First and second intake valves and exhaust valves that open and close are provided, and the cylinder head has a main port having an inlet opening on one side of the cylinder head in a direction orthogonal to the axis, and a main port that is connected to the main port. 2
an intake port composed of first and second branch ports that are divided into hands and reach the first and second intake valve ports, respectively; and an outlet that is connected to the exhaust valve port and is perpendicular to the axis of the cylinder head. An exhaust port that opens on the other side in the direction is formed corresponding to each combustion chamber, and the main port is connected to the first and second ports so that the second branch port is oriented in a substantially tangential direction of the periphery of the combustion chamber. Since it is arranged offset from the center between the intake valve ports toward the first intake valve port, swirl is generated in the intake air-fuel mixture in the combustion chamber without forming a swirl wall that would increase intake resistance at the intake port. The air-fuel ratio of the air-fuel mixture can be made uniform, and the swirl direction is from the ignition source to the exhaust valve.
As a result, the air-fuel mixture is transported to the vicinity of the high-temperature exhaust valve immediately after ignition, which, together with the swirl effect, accelerates the rise of combustion, shortens the combustion time, improves anti-knotting properties, and improves overall combustion. Significant improvements are achieved, facilitating high power performance and reducing fuel consumption. Moreover, since it is a multi-cylinder internal combustion engine, there is a restriction that each intake port is opened all at once on one side of the cylinder head in a direction perpendicular to the crankshaft axis.
The second branch port of the intake port is oriented approximately tangentially to the periphery of the combustion chamber by an extremely simple configuration in which the main port that opens on one side is offset toward the first intake valve port as described above. This allows the swirl to occur easily.

In addition, by configuring the ceiling surface of the combustion chamber as two slopes descending from the ridgeline in the approximate center toward both sides, each slope has a relatively high degree of freedom for intake and exhaust valve ports with sufficient opening area. In particular, the exhaust valve port can be placed as far away as possible from the second intake valve port, which is the main outlet of the swirl, so that the swirl path of the swirl can be made long. It is possible to effectively prevent the air-fuel mixture from blowing through from the second intake valve port to the exhaust valve port during valve polymerization, contributing to reducing the amount of unburned components generated in the exhaust gas. Since it can be brought as close as possible to the center of the combustion chamber without being obstructed by the air, the anti-knocking property can be further improved. Furthermore, since the axes of the first and second intake valves opening in parallel on the ceiling slope, and thus the axes of the first and second intake valves, can be made substantially parallel to each other, both intake valves and The interlocking mechanism between the valve camshafts can be simplified.

Furthermore, in each of the outermost combustion chambers, the first intake valve port is located closer to the center of the cylinder head than the second intake valve port, so that the main port and cylinder head of the intake port corresponding to each outermost combustion chamber are Since the intake manifold, in which the outermost branch pipe is connected to the main port, can be made smaller in the crankshaft direction.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is an overall bottom view of the cylinder head, FIG. 2 is a partially enlarged view of FIG. 1, and FIGS. 3 and 4 are views of FIG. 2.
FIG. 5 is a vertical cross-sectional view of the internal combustion engine taken along lines 1 and 2, respectively, and a diagram showing the opening/closing timing of the intake and exhaust valves of this engine. 1...Cylinder block, 2...Cylinder head,
6... Combustion chamber, 7... Ceiling surface, 7 ₁ , 7 ₂ ... Slope, 8...
Ridge line, 9 ₁ , 9 ₂ ... first and second intake valve ports, 10 ... exhaust valve port, 11 ... spark plug as ignition source, 12 ... intake port, 12 m ... main port, 12 ₁ , 12 ₂ ... first , second intake valve, 14...exhaust port, 18...exhaust valve.

Claims (1)

[Scope of Claims] 1. A cylinder head is provided with a plurality of combustion chambers lined up along the axis of the crankshaft, and the ceiling surface of each combustion chamber is extended from a ridgeline at a substantially central portion extending parallel to the axis on both sides. A pair of first and second intake valve ports are opened in parallel along the ridge line on one slope, and a pair of first and second intake valve ports are opened on the other slope facing the first intake valve port. an ignition source is disposed opposite the second intake valve port, and a second intake valve is provided at the first and second intake valve ports and an exhaust valve port for opening and closing the same. 1. A second intake valve and an exhaust valve are respectively provided, and the cylinder head has a main port having an inlet opening on one side of the cylinder head in a direction perpendicular to the axis, and a main port having two ports from the main port. an intake port consisting of first and second branch ports that are separated and lead to the first and second intake valve ports, respectively; and an outlet that is connected to the exhaust valve port and extends in a direction perpendicular to the axis of the cylinder head. An exhaust port opening on the other side is formed corresponding to each combustion chamber, and the main port is connected to the first and second intake valves so that the second branch port is oriented in a substantially tangential direction of the periphery of the combustion chamber. The first intake valve port is arranged offset from the center between the openings toward the first intake valve port side, and furthermore, the first intake valve port is arranged closer to the center of the cylinder head than the second intake valve port in each outermost combustion chamber. A three-valve multi-cylinder internal combustion engine. 2. In what is stated in claim 1,
A three-valve multi-cylinder internal combustion engine, wherein the opening timing of the first intake valve is delayed from that of the second intake valve.