JPH07269360A - Combustion chamber of internal combustion engine - Google Patents

Abstract

PURPOSE:To enable suction tumbling to be surely formed by providing a restraining means on the inner wall of a combustion chamber along the outer circumferential part equivalent to almost a half circumference of a seat of the suction valve continuous to the curved inner circumferential part side of a suction port for the purpose to weaken the suction current in the gap between the inner wall and the suction valve outer circumferential surface. CONSTITUTION:Regarding those that have suction air tumbling formed on the inside of a combustion chamber 3 by a strong current produced on the curved outer circumferential part 2a of a suction port 2, a protrusion (or a cavity) is formed on the inner wall 3b of a combustion chamber 3 along the outer circumferential part equivalent to almost a half circumference of the seat 7 of a suction valve 5 in succession to the inner circumferential part 2b on thee opposite side of the outer circumferential part 2a of the suction port 2 as a restraining means to weaken the suction air current flowing through the gap between a suction valve outer circumferential surface 5a as much as possible. Thus suction air current flowing into the combustion chamber 3 not being able to follow the sharp formational change of the suction air port 2 at the protrusion 8 section but making partial disturbance is causing the suction air flowing through a gap b to reduce its flow velocity and enabling suction air tumbling flow to be formed for certain.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber of an internal combustion engine in which the intake tumble generated in the combustion chamber during intake into the combustion chamber is increased by the shape of the combustion chamber.

[0002]

2. Description of the Related Art In recent automobile internal combustion engines, combustion in a combustion chamber is improved in order to achieve low fuel consumption and low pollution by achieving lean burn by stratified intake air. One of the methods of igniting the fresh air-fuel mixture in the combustion chamber and improving the combustibility is a method of generating an intake swirl in the combustion chamber due to the shape of the intake port in the cylinder head during intake into the combustion chamber. The intake swirl includes one that swirls the intake air laterally around the axis of the cylinder bore in the combustion chamber and one that swirls the intake air vertically in the combustion chamber in the axial direction of the cylinder bore (hereinafter referred to as the intake tumble). It is well known.

As a structure for generating intake tumble as in the latter case, as shown in FIG. 6, the intake port 22 in the cylinder head 21 is connected to the cylinder head 2.
1 is curved downward from the side surface of the intake chamber 1 toward the combustion chamber 23, and intake air is drawn into the curved outer peripheral portion, that is, the intake port 2
By allowing the inner surface of 2 to flow along the ceiling 22a, the intake air flows into the combustion chamber from the communication portion indicated by the symbol a between the inner peripheral surface 22b of the circular opening and the outer peripheral surface 25a of the intake valve 25. However, the intake tumble shown by the one-dot chain line arrow C is generated in the combustion chamber 23. However, on the other hand, a part of the intake air also flows into the combustion chamber 23 from the communication part on the opposite side of the reference sign a indicated by the reference sign b, and an intake tumble shown by a dotted arrow D is generated in the combustion chamber 23. Since the collision occurs with the intake tumble indicated by the arrow C, there is a problem that the intake tumble indicated by the arrow C in the combustion chamber 23 is considerably reduced. In particular, the intake tumble indicated by the arrow C is reduced. The tendency to be performed remarkably appears in the low load region where the intake air amount is small.

Therefore, conventionally, the cross-sectional area of the intake port 22 is reduced to improve the flow velocity of the intake air in the intake port 22, or, for example, it is described in JP-A-55-2532. As described above, the intake air in the intake port 22 is curved at the outer peripheral portion, that is, the ceiling 2 of the inner surface of the intake port 22.
The intake tumble indicated by the arrow C is increased by providing a deflector plate for deflecting the current so as to flow along 2a.

[0005]

However, in such a conventional example, it is necessary to reduce the cross-sectional area of the intake port or to provide a flow diverter plate in the intake port in the high load region where the intake amount is large. There is a problem that the output of the internal combustion engine decreases in the high load range because the flow resistance in the intake port is large and the efficiency of charging the intake chamber with the combustion chamber is low. An object of the present invention is to provide a combustion chamber capable of reliably forming an intake tumble in the combustion chamber without causing an increase in the resistance of the flow of intake air in the intake port.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a cylinder head on the upper surface of a cylinder block having a cylinder bore is provided with a combustion chamber which is recessed in the lower surface and opens into the cylinder bore. In the internal combustion engine, which is provided with an intake valve that opens and closes an open intake port, and a strong intake flow generated in the curved outer peripheral portion of the intake port forms an intake flow that vertically swirls in the axial direction of the cylinder bore in the combustion chamber, The inner wall of the combustion chamber in the vicinity of the valve seat of the intake valve, which continues to the inner peripheral portion on the side opposite to the outer peripheral portion of the curve of the port, reduces the intake flow in the gap between the inner wall and the intake valve as much as possible. It is characterized in that suppression means is installed.

[0007]

According to the above construction, when the intake valve for opening and closing the intake port opening to the combustion chamber is opened and the intake air flows from the intake port into the combustion chamber due to the pressure difference between the combustion chamber and the intake port, Although a part of the intake air flows along the inner wall of the combustion chamber, the inner wall of the combustion chamber along the outer peripheral portion corresponding to approximately half the circumference of the valve seat of the intake valve following the inner peripheral portion of the curved intake port, Since the suppressing means for weakening the intake air flow in the gap between the inner wall and the intake valve is provided as much as possible,
When the flow of the intake air flowing into the combustion chamber is applied to this portion, it cannot follow the abrupt shape change and local turbulence occurs, so that the inner wall provided with the suppressing means and the intake valve facing the inner wall are provided. The flow velocity of the intake air flowing through the gap decreases, and the amount of intake air flowing through the gap decreases. On the other hand, the gap on the side opposite to the gap, that is, the amount of intake air flowing through the gap between the inner wall of the combustion chamber in which the suppressing means is not provided and the intake valve facing the inner wall increases by the above-mentioned reduced amount, The latter intake air flow is stronger than the former one, and a strong vertical intake tumble can be generated in the combustion chamber.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section of a main part of an internal combustion engine of a first embodiment of the present invention, and FIG. 2 shows a plan view of a part of a lower surface of a cylinder head of the internal combustion engine of the first embodiment. Reference numeral 11 in the drawing denotes a cylinder block provided with a cylinder bore 12, and a cylinder head 1 is attached to the upper surface of the cylinder block 11, the lower surface of which is recessed to form a combustion chamber 3 opening into the cylinder bore 12. The cylinder head 1 is provided with an intake port 2 which is curved downward from this side surface toward the combustion chamber 3 and is provided with the cylinder bore 12.
In contrast, the cylinder head 1 is provided in a direction orthogonal to the front-rear direction F.

In the embodiment of the present invention, two intake ports 2 per cylinder are arranged in series in the front-rear direction F of the cylinder head 1 at approximately half of the ceiling of the combustion chamber 3 on the intake port 2 side. The openings are arranged side by side, and opened and closed by an intake valve 5 provided at the inlet of the combustion chamber 3 at this opening. Further, two exhaust ports 4 are opened at positions on the ceiling of the combustion chamber 3 opposite to the opening side of the intake ports 2 facing the intake valves 5, and the exhaust valves are the same as the intake valves 5. 6 are provided.

An intake valve 5 is provided on the inner wall of the ceiling of the combustion chamber 3.
The valve seat 7 of the intake valve 5 that abuts when the intake port 2 is closed. The outer peripheral portion of the valve seat 7 corresponds to a half circumference of the cylinder head 1 farther from the center line in the front-rear direction F. When the intake valve 5 is opened, the inner wall 3b of the combustion chamber 3 along the inner wall 3b of the combustion chamber 3, that is, the inner wall 3b of the combustion chamber 3 following the curved inner peripheral portion 2b side of the intake port 2, A protrusion 8 as a suppressing means for weakening the intake air flow flowing through the gap b between the inner wall 3b and the outer peripheral surface 5a of the intake valve 5 facing the inner wall 3b is formed in a trapezoidal cross section, It is erected from the inner wall surface of the combustion chamber 3 toward the outer peripheral surface 5a of the intake valve 5.

According to this structure, when intake air flows in the curved intake port 2, the flow velocity of the intake air flowing along the curved outer peripheral portion 2a, that is, along the ceiling portion of the inner surface of the intake port 2 is equal to that of the curved intake port 2. The dashed-dotted line in FIG. 1 that is larger than the flow velocity of the intake air flowing along the curved inner peripheral portion 2b opposite to the outer peripheral portion 2a and swirls vertically in the axial direction of the cylinder bore 12 in the combustion chamber 3. The flow indicated by arrow A, that is, the intake tumble is generated.

In addition to this, since the protrusion 8 is provided on the inner wall 3b, when the flow of the intake air flowing into the combustion chamber 3 reaches the portion of the protrusion 8, it cannot follow the abrupt shape change. Since the protrusion 8 locally disturbs, the flow velocity of the intake air flowing through the gap b is reduced and the intake amount is decreased, so that the gap a on the opposite side of the gap b, that is, the protrusion 8 is not provided. Since the amount of intake air flowing through the gap a between the inner wall 3a of the combustion chamber 3 and the outer peripheral surface 5a of the intake valve 5 facing the interior wall 3a increases by the above-described decrease, the intake air that has flowed into the combustion chamber 3 The intake flow indicated by the one-dot chain line arrow A exceeds the intake flow indicated by the dotted arrow B, and the intake flow in the vertical direction can be further increased in the combustion chamber 3 to generate a strong intake tumble. .

FIG. 3 shows a cross section of a main part of an internal combustion engine of the second embodiment of the present invention, and FIG. 4 shows a plan view of a part of the lower surface of the cylinder head of the internal combustion engine of the second embodiment. In contrast to that in the first embodiment, the second embodiment is constituted by a protrusion as a suppressing means for weakening the intake air flow flowing through the gap b as much as possible. The configuration is the same except that the configuration is different. Therefore, the same constituents are designated by the same reference numerals as those in the first embodiment. As shown in FIG. 3, the inner wall 3 at the same position as in the first embodiment.
A recess 9 is formed in b as a suppressing means for weakening the intake air flow flowing through the gap b as much as possible. The recess 9 has a U-shaped cross section and is recessed from the inner wall surface of the combustion chamber 3. ing. With this configuration, as in the case of the first embodiment, the flow of the intake air cannot locally follow the abrupt shape change in the depression 9 and local turbulence occurs, so that the flow velocity of the intake air flowing through the gap b decreases. As a result, the amount of intake air decreases, and the amount of intake air flowing through the gap a on the opposite side increases by this amount.
The intake flow indicated by the arrow exceeds the intake flow indicated by the arrow B, and the combustion chamber 3
A similar effect of generating a stronger intake tumble inside is obtained.

In the embodiment of the present invention, the case where the present invention is applied to an internal combustion engine having two intake valves 5 per cylinder has been described, but the present invention is not limited to the number of intake valves 5. Needless to say. Further, the projections 8 and the depressions 9 as the suppressing means for weakening the intake air flow as much as possible in the embodiment of the present invention are not limited to those formed integrally with the cylinder head 1, but the projections 8 and the depressions 9 may be formed in the cylinder head. It is also possible to apply it by molding it separately from 1 and then fixing it to the cylinder head 1 by press fitting or caulking. Further, as shown in FIG. 5, the projection 8 may be formed integrally with the valve seat 7 of the intake valve 5 and cast into the inner wall 3b of the combustion chamber 3 of the cylinder head 1. According to this structure, the protrusions 8 and the depressions 9 can be accurately processed and then attached to the cylinder head 1. Therefore, it is easy to secure a shape sensitive to the generation of vortices and turbulence of the air flow, and the gap b The turbulence of the flow of the intake air that flows into the cylinder is accurately generated, and the flow of the intake air in the gap b can be reliably suppressed.

[0015]

According to the present invention, the following effects can be obtained. The intake flow in the gap between the inner wall and the outer peripheral surface of the intake valve can be applied to the inner wall of the combustion chamber along the outer peripheral portion corresponding to approximately half the circumference of the valve seat of the intake valve following the inner peripheral side of the curve of the intake port. Since the suppression means for weakening as much as possible is provided,
The cross-sectional area of the intake port can be reduced without increasing the resistance of the intake flow in the intake port,
Alternatively, there is no problem that the resistance of the flow of the intake air is large as in the case where the deflector plate is provided in the intake port, the efficiency of filling the intake air into the combustion chamber is reduced, and the output of the internal combustion engine is reduced in the high load range. An intake tumble in the combustion chamber can be reliably formed.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of an internal combustion engine according to a first embodiment of the present invention.

FIG. 2 is a plan view of a part of the lower surface of the cylinder head of the internal combustion engine of the first embodiment of the present invention.

FIG. 3 is a sectional view of a main part of an internal combustion engine according to a second embodiment of the present invention.

FIG. 4 is a plan view of a part of the lower surface of the cylinder head of the internal combustion engine of the second embodiment of the present invention.

FIG. 5 is a sectional view of an essential part of an internal combustion engine of another embodiment of the present invention.

FIG. 6 is a sectional view of a main part of a conventional internal combustion engine.

[Explanation of symbols]

 1 Cylinder Head 2 Intake Port 2a Outer Portion of Intake Port 2b Inner Portion of Intake Port 3 Combustion Chamber 5 Intake Valve 7 Valve Seat 8 Protrusion (Suppressing Means) 9 Depression (Suppressing Means) 11 Cylinder Block 12 Cylinder Bore b Gap

Claims (1)

[Claims] 1. An intake air which opens and closes an intake port opening in the combustion chamber by recessing the lower surface in a cylinder head on an upper surface of a cylinder block having a cylinder bore. In an internal combustion engine that is provided with a valve and forms an intake flow that vertically swirls in the axial direction of the cylinder bore in the combustion chamber by a strong intake flow that occurs at the curved outer peripheral part of the intake port, what is meant by the curved outer peripheral part of the intake port? On the inner wall of the combustion chamber adjacent to the valve seat of the intake valve, which follows the inner peripheral portion on the opposite side, is installed a suppressing means for weakening the intake air flow in the gap between the inner wall and the intake valve as much as possible. A combustion chamber of an internal combustion engine characterized by: