JPH07111132B2 - Combustion chamber of internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a combustion chamber of an internal combustion engine.

(Problems to be Solved by Related Art and Invention) In order to improve output performance and the like, an internal combustion engine provided with a plurality of intake and exhaust valves is known. As a combustion chamber of such an internal combustion engine, Generally, a hemispherical combustion chamber in which valves can be easily arranged is used.

However, when a hemispherical combustion chamber is used for such an internal combustion engine, the intake air from the intake valve may not smoothly flow into the combustion chamber depending on the wall shape of the combustion chamber, which may adversely affect the intake charge rate. .

The hemispherical combustion chamber 1 shown in FIG.
Inclining with respect to the central axis of the intake valve 2, the wall surface of the combustion chamber around the valve opening 3 is formed with a hemispherical shape centered on the axis of the intake valve 2 (Actual publication 51- 21203
(See Japanese Patent Laid-Open Publication No. 2003), such a shape gives resistance to the intake air flowing from the intake valve 2 regardless of the radius of the hemisphere.

That is, when the radius of the hemispherical surface is set to R ₁ and the combustion chamber wall surface is in contact with the seat surface 5 of the valve seat 4, the intake air from the intake valve 2 flows in at the seat surface angle Θ of the valve seat 4. On the other hand, the inflow angle Θ is sandwiched by the wall surface from Θ to Θ ₁ as shown in FIG. 6, which causes a vortex of the inflow intake air on the intake valve 2 side, resulting in a loss.

When the radius of the hemisphere is set to R ₂ which is larger than R ₁ , the wall angle Θ ₂ becomes larger than the inflow angle Θ as shown in FIG. Occurs, which is also a loss. In this case, since the wall surface at the center of the combustion chamber where the spark plug is arranged becomes a groove-shaped recess, fuel is likely to concentrate and smoldering of the spark plug is likely to occur.

Therefore, in such a hemispherical combustion chamber, there is a problem that the intake filling rate is lowered due to the loss when the intake air flows in, and sufficient output performance cannot be obtained.

Further, in the case of such a hemispherical combustion chamber, there is a problem that the structure becomes more complicated as the number of intake valves and the like increases, and manufacturability deteriorates.

The present invention aims to solve such problems.

(Means for Solving the Problem) In the present invention, in a combustion chamber of an internal combustion engine including a plurality of intake valves, a combustion chamber wall surface between valve ports corresponding to each intake valve is provided from an opening face end of the valve port. It is formed by a flat surface, and the other combustion chamber wall surface around each valve opening is formed by a conical surface from the end of the valve seat surface of the valve opening.

(Operation) Therefore, the intake air from each intake valve smoothly flows along the conical wall surface of the combustion chamber connected to the valve seat surface of each valve opening, and does not cause a loss. Further, although the intake air also flows between the valve openings, the flow on the side of the peripheral conical wall surface becomes the main flow, so that the loss along the planar wall surface between the valve openings is small.

(Embodiment) FIGS. 1 to 4 show an embodiment of the present invention, in which 10 is a combustion chamber, 11 is a cylinder head forming the combustion chamber 10, 12 is a cylinder block, 13 is a piston, and 14 is ignition. It is a stopper.

The combustion chamber 10 has an intake port formed in the cylinder head 11.
The intake valve ports 17a, 17b and the exhaust valve ports 18a, 18b communicating with the exhaust port 16 and the exhaust port 16 are opened in parallel in a state of being inclined at a predetermined angle with respect to the central axis of the combustion chamber 10, and the intake valve port 17a,
Valve seats 19 and 20 on which intake and exhaust valves (not shown) are seated are fitted to 17b and exhaust valve openings 18a and 18b, respectively.

Then, between the intake valve openings 17a, 17b and between the exhaust valve openings 18a, 18b, the wall surfaces 21, 22 of the combustion chamber 10 are continuous with the opening surfaces of the corresponding valve openings 17a, 17b, 18a, 18b. Thus, it is formed in a planar shape extending from each corresponding opening surface.

On the other hand, the wall surfaces 23a, 23b, 24a, 24b of the combustion chamber 10 around the intake valve openings 17a, 17b and the exhaust valve openings 18a, 18b excluding the wall surfaces 21, 22.
(Stripe pattern part in Fig. 3) is the corresponding valve opening 17a,
17b, 18a, 18b is formed in a conical surface extending from the corresponding seat surfaces 25, 26 so as to be continuous with the seat surfaces 25, 26 of the valve seats 19, 20. In the present embodiment, the angle Θ ₁ formed by the seat surface 25 and the intake valve center line O ₁ is the same as the angle Θ ₂ formed by the wall surfaces 23a, 23b and the intake valve center line O ₂ , but Θ ₁ is Θ _{1. It} may be slightly larger or smaller than ₂ . Similarly, in the present embodiment, Θ formed by the seat surface 26 and the exhaust valve center line O ₂ is
₃ is the same as the angle Θ ₄ formed by the wall surfaces 24a, 24b and the exhaust valve center line O ₂ , but Θ ₃ may be slightly larger or slightly smaller than Θ ₄ .

The boundary portion 27 between the wall surfaces 23a and 24a and the boundary portion 28 between the wall surfaces 23b and 24b have a mountain-shaped protruding shape. May be formed with a smooth curved surface.

Also, on both sides of the wall surfaces 21 and 22, the end surface 3 of the cylinder head 11 is
1,32 are formed so as to project in an arc shape.

With such a configuration, the intake air from the intake port 15 flows into the combustion chamber 10 at an angle of the seat surface 25 of the valve seat 19 from the intake valve openings 17a and 17b when the intake valve is opened.
Intake air toward the outside of 17a, 17b is
Since 3b is a conical surface extending from the seat surface 25, respectively, it smoothly flows in along the conical wall surfaces 23a, 23b without generating a vortex.

In addition, when a plurality of intake valve openings 17a and 17b are provided in this way, the flow of intake air toward these outer circumferences becomes the main flow,
Most of the intake air flows along the surrounding conical wall surfaces 23a, 23b. Therefore, the intake air also flows into between the intake valve openings 17a and 17b, but the intake air amount is small, so
Even if the wall surface 21 between a and 17b is flat, the inflow resistance is small.

Further, the exhaust gas that has finished combustion in the combustion chamber 10 is discharged from the exhaust valve openings 18a, 18b along the conical wall surfaces 24a, 24b and the planar wall surface 22 around the exhaust valve openings 18a, 18b when the exhaust valve is opened. It smoothly flows to the exhaust port 16.

Therefore, the inflow loss of intake air is significantly reduced, and a good exhaust action is obtained, whereby a high intake charge rate can be secured and sufficient output performance of an internal combustion engine equipped with a plurality of intake valves can be secured.

In addition, the wall surfaces 21, 22 between the respective valve openings 17a and 17b and 18a and 18b
Since the flat surface is formed, the structure is simplified and the manufacturability is improved.

The wall surface 29 at the center of the combustion chamber 10 in which the spark plug 14 is arranged is
Because of the convex shape, smoldering of the spark plug 14 does not occur due to the concentration of fuel.

Further, it goes without saying that the present embodiment can be applied to an internal combustion engine equipped with three or more intake and exhaust valves.

(Effects of the Invention) As described above, according to the present invention, in a combustion chamber of an internal combustion engine including a plurality of intake valves, the wall surface of the combustion chamber between the valve ports corresponding to the intake valves is defined as the opening face end of the valve port. Since it is formed as a flat surface from each part and the other combustion chamber wall surface around each valve opening is formed as a conical surface from the valve seat surface end of the valve opening, the intake flow loss can be reduced while simplifying the structure. A high intake filling rate can be secured,
A combustion chamber suitable for an internal combustion engine having a plurality of intake valves can be provided.

[Brief description of drawings]

1 to 4 are plan views of a combustion chamber showing an embodiment of the present invention, a sectional view taken along the line AA, a schematic perspective view and a partial sectional view, and FIGS. 5 to 7 are conventional examples. FIG. 17a, 17b …… Intake valve port, 19 …… Valve seat, 21 …… Wall surface, 2
3a, 23b …… Wall surface, 25 …… Seat surface.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-61-142321 (JP, A) JP-B 47-29607 (JP, B1) JP-A-57-501133 (JP, A)

Claims (1)

[Claims] 1. In a combustion chamber of an internal combustion engine having a plurality of intake valves, a combustion chamber wall surface between valve openings corresponding to each intake valve is formed in a plane from the opening end of the valve opening, and each valve is formed. A combustion chamber of an internal combustion engine, wherein another combustion chamber wall surface around the mouth is formed as a conical surface from the end of the valve seat surface of the valve mouth.