JPH05179959A - Four valve type internal combustion engine - Google Patents

Abstract

PURPOSE:To improve quick ignitability and combustibility of intake mixture, in a four valve type internal combustion engine provided with two intake ports and two exhaust ports against one combustion chamber. CONSTITUTION:In a combustion chamber 5, a protrudent part 18 to divide the combustion chamber 5 into a first combustion chamber 5a comprising one intake port 6 and one exhaust or 8 and a second combustion chamber 5b comprising the other intake port 7 and the other exhaust port 9 is provided. The underside of the protrudent part 18 is formed in a squish area 10 against the top face of a piston. The one intake port 6 is constituted into a tumble port by which intake mixture from the intake port 6 is given loop-like swirl in the vertical direction. Meanwhile, the other intake port 7 is constituted into a swirl port by which intake mixture from the intake port is given loop-like swirl in the lateral direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is of a so-called four-valve type in which two intake valves and two exhaust valves are provided for one combustion chamber provided with an ignition means such as a spark plug at a substantially center thereof. It relates to an internal combustion engine.

[0002]

2. Description of the Related Art In a four-valve internal combustion engine of this type, one combustion chamber provided with a spark plug has two intake ports each provided with an intake valve, and two exhaust ports also provided with each exhaust valve. Are disposed in regions on both the left and right sides of the longitudinal center line that extends substantially parallel to the crankshaft through the substantially center of the combustion chamber in plan view, as disclosed in Japanese Patent Publication No. 49-23848 as a prior art. Actual exploitation 57-22628
It is described in Japanese Patent Publication No.

The four-valve internal combustion engine in this prior art is configured so that two intake ports are provided with a longitudinal looped vortex (tumble flow) to each of the intake air-fuel mixtures sucked from the intake ports. In addition to the above, in the peripheral contour of the combustion chamber, the portion between the intake ports,
And, a part between the both exhaust ports is made to enter toward the center of the combustion chamber to form two squish areas for the top surface of the piston, and the squish flow from the both squish areas and the both tumble flows. It is designed to promote the ignition and combustion of the intake air-fuel mixture.

[0004]

However, in the case of this prior art, the direction of flame propagation from the spark plug is outward from the substantial center of the combustion chamber toward the outer peripheral direction, whereas the piston is At the time of approaching to the top dead center, the squish flow from both squish areas is inward from the outer circumference toward the center, in other words,
The direction of the squish flow from the both squish areas is
Since it is opposite to the flame propagation direction from the spark plug, the flame propagation velocity from the spark plug is reduced by the both squish flows.

Moreover, in the above-mentioned prior art, since the looped vortex flow in the intake air mixture from one intake port and the looped vortex flow in the intake air mixture from the other one intake port are in the same direction, Since it is not possible to apply a violent turbulent state in the vicinity of the spark plug, combined with the fact that the flame propagation velocity is reduced by the squish flow as described above, rapid ignition / combustion of a lean intake air-fuel mixture is performed. There was a problem that could not be achieved sufficiently.

The present invention has a technical problem to solve this problem.

[0007]

In order to achieve this technical object, the present invention is directed to one combustion chamber provided with an ignition means such as a spark plug, two intake ports each provided with an intake valve, and the like. A four-valve system in which two exhaust ports each having an exhaust valve are distributed and arranged in regions on both left and right sides of a longitudinal centerline that extends substantially parallel to the crankshaft through a substantially center of the combustion chamber in a plan view. In an internal combustion engine, a first combustion chamber in which the one combustion port and the one exhaust port are opened and a second combustion in which the other intake port and the other exhaust port are opened in the combustion chamber hole on the inner surface of the combustion chamber. A ridge that divides into a chamber is integrally formed, the lower surface of the ridge is formed in a squish area for the top surface of the piston, and the ignition means is disposed in the squish area.
One intake port that communicates with the combustion chamber is configured as a tumble port that imparts a vertical looped vortex to the intake air mixture from the intake port, while the other intake port that communicates with the second combustion chamber The swirl port is configured to give a lateral looped vortex to the intake air mixture from the intake port.

[0008]

[Operation] With this configuration, during the intake stroke due to the downward movement of the piston, a vertical looped vortex flow is generated for the intake air-fuel mixture from one intake port, and to the intake air-fuel mixture from the other intake port. Can provide a lateral looped vortex flow, and then, during the compression stroke by the upward movement of the piston, both the vertical looped vortex flow and the lateral looped vortex flow are compressed while disturbing each other. As a result, a severe turbulent flow state can be generated in the combustion chamber.

At the end of the compression stroke, a squish flow is generated between the squish area on the lower surface of the ridge and the top surface of the piston, and the squish flow extends from the ridge to the first combustion chamber and While ejecting outward toward both of the second combustion chambers, the flame from the ignition means arranged in the squish area on the lower surface of the raised portion also faces both of the first combustion chambers and the second combustion chambers. And propagate outward.

That is, the direction of the squish flow from the squish area on the lower surface of the ridge is the same as the direction of flame propagation, and the flame is placed on the squish flow from the squish area on the lower surface of the ridge. ,
Since it can diffuse over the entire area of both the first combustion chamber and the second combustion chamber, the propagation velocity of the flame can be greatly accelerated.

[0011]

Therefore, according to the present invention, both of the longitudinal turbulent flow and the lateral vortex flow are disturbed by each other and the turbulent flow is accelerated, and the flame velocity is accelerated. Since rapid ignition / combustion can be surely achieved, the air-fuel ratio in the intake air-fuel mixture can be made lean and the knock resistance can be improved.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. In the drawing, reference numeral 1 denotes a cylinder block having a cylinder bore 2, reference numeral 3 denotes a cylinder head fastened to the upper surface of the cylinder block 1, and a reciprocating piston 4 is provided in the cylinder bore 2 of the cylinder block 1. And the cylinder head 3 is inserted.
A combustion chamber 5 is formed on the lower surface of the recess.

Reference numerals 6 and 7 denote two intake ports open to the combustion chamber 5, and reference numerals 8 and 9 similarly denote the combustion chamber 5.
And two exhaust ports 8 and 9 are shown in FIG. 2, and these intake ports 6 and 7 and exhaust ports 8 and 9 pass through substantially the center of the combustion chamber 5 and the crankshaft ( (Not shown), with the longitudinal center line 10 extending substantially parallel to the left and right sides being sandwiched, the left and right regions are distributed and arranged.
Further, intake valves 11 and 12 are provided at the openings of the intake ports 6 and 7 into the combustion chamber 5, and exhaust valves 13 and 14 are provided at the openings of the exhaust ports 8 and 9 into the combustion chamber 5. Are provided respectively. Further, intake pipes 15 and 16 for guiding air from an air cleaner (not shown) to the intake ports 6 and 7 are connected to the openings of the intake ports 6 and 7 to the side surface 3a of the cylinder head 3. Has been done.

In this case, both of the intake ports 6,
By making one of the intake ports 6 out of the one of the intake ports 6 substantially straight from the opening for the side surface 3 a of the cylinder head 3 toward the opening for the combustion chamber 5, the intake air mixture from the one intake port 6 is discharged. As shown by an arrow A in FIG. 1, a tumble port that gives a vertical vortex flow is formed, while the other intake port 7 of the intake ports 6 and 7 is curved in the middle, Alternatively, by forming a swirl chamber 17 in the portion of the intake valve 12 so as to surround the intake valve 12, the intake air-fuel mixture from the other intake port 7 is subjected to a lateral loop as shown by an arrow B in FIG. It is configured as a swirl port that imparts a vortex flow.

In the combustion chamber 5, the first combustion chamber 5a in which one intake port 6 and one exhaust port 8 open in the combustion chamber 5, the other intake port 7 and the other exhaust port 5a. The raised portion 18 that divides into the second combustion chamber 5b in which the opening 9 is formed is integrally formed so that the raised portion 18 extends in a direction substantially perpendicular to the longitudinal center line 10, and the raised portion 1 is formed.
The lower surface of 8 is formed in the squish area 19 with respect to the top surface of the piston 4. Further, the cylinder head 3 is provided with a spark plug 20 and an electrode portion 20 of the spark plug 20.
It is screwed so that a is located in the squish area 19.

In this case, by providing the raised portion 18 at a position deviated from the center of the combustion chamber 5 toward the first combustion chamber 5a by an appropriate dimension, the second combustion chamber 5b can be moved to the first combustion chamber 5b.
It is configured to be larger than the combustion chamber 5a. In this configuration, during the intake stroke due to the downward movement of the piston 4, the intake air-fuel mixture that flows into the first combustion chamber 5a and the second combustion chamber 5b from both intake ports 6 and 7 flows from one intake port 6 The intake air mixture to be operated is indicated by arrow A in FIG.
3, a vertical loop-shaped vortex flow can be imparted to the intake air-fuel mixture from the other intake port 7, as shown by an arrow B in FIG.
Next, during the compression stroke due to the upward movement of the piston 4,
By virtue of both the vertical vortex flow in the vertical direction and the vortex flow in the horizontal direction entering each other and being turbulently compressed, a violent turbulent state can be generated in the combustion chamber 5.

At the end of the compression stroke, a squish flow is generated between the squish area 19 on the lower surface of the raised portion 18 and the top surface of the piston 4, and the squish flow passes from the raised portion 18 to the first portion. 1 combustion chamber 5a
And the second combustion chamber 5b, the flame from the spark plug 20 arranged in the squish area 19 on the lower surface of the raised portion 18 is also ejected outward.
It propagates outward toward both the combustion chamber 5a and the second combustion chamber 5b. That is, the direction of the squish flow from the squish area 19 on the lower surface of the raised portion 18 and the direction of flame propagation from the spark plug 20 become substantially the same direction, and the flame is transferred to the squish area on the lower surface of the raised portion 18. Since the squish flow from 19 can be diffused over the entire area of both the first combustion chamber 5a and the second combustion chamber 5b, the propagation speed of the flame can be greatly accelerated.

Incidentally, in place of the spark plug 22 in the above-mentioned embodiment, as described in, for example, Japanese Utility Model Publication No. 54-19441 and Japanese Utility Model Publication No. 54-38401,
It goes without saying that other ignition means may be applied, for example, a sub-chamber cup surrounding the spark plug provided with a plurality of ejection holes may be used. In addition, the first combustion chamber 5a and the second combustion chamber 5
Although the b may be configured to have the same size by providing the raised portion 18 at the center of the combustion chamber 5,
As in the above-described embodiment, by providing the raised portion 18 at a position deviated from the center of the combustion chamber 5 toward the first combustion chamber 5a by an appropriate dimension, the second combustion chamber 5b is replaced by the first combustion chamber 5a.
By making it larger than the above, the longitudinal loop-shaped vortex flow on the first combustion chamber 5a side can be strengthened, while the lateral loop-shaped vortex flow swirling in the second combustion chamber 5b is smoothed. Therefore, it is more effective.

[Brief description of drawings]

1 is a vertical sectional front view showing an embodiment of the present invention, which is indicated by I in FIG.
FIG. 3 is a sectional view taken along line I.

FIG. 2 is a bottom view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

[Explanation of Codes] 1 cylinder block 2 cylinder bore 3 cylinder head 4 piston 5 combustion chamber 5a first combustion chamber 5b second combustion chamber 6,7 intake port 8,9 exhaust port 11,12 intake valve 13,14 exhaust valve 15, 16 Air intake pipe 18 Raised part 19 Squish area 20 Spark plug

Claims (1)

[Claims] 1. A combustion chamber provided with an ignition means such as a spark plug, two intake ports each provided with an intake valve, and two exhaust ports each provided with an exhaust valve are provided in a plan view. In a four-valve internal combustion engine, which is arranged so as to be distributed on both left and right sides of a longitudinal centerline that extends substantially parallel to the crankshaft through substantially the center of the combustion chamber, the combustion chamber hole is provided on the inner surface of the combustion chamber. A raised portion that divides into a first combustion chamber in which the one intake port and one exhaust port are open and a second combustion chamber in which the other intake port and the other exhaust port are open are integrally formed, The lower surface of the raised portion is formed in a squish area with respect to the top surface of the piston, and the ignition means is arranged in this squish area, while one intake port communicating with the first combustion chamber is connected to the intake port from the intake port. Vertical to the mixture , And the other intake port communicating with the second combustion chamber is configured as a swirl port for imparting a lateral looped vortex to the intake air mixture from the intake port. A four-valve internal combustion engine characterized in that