JPH02248618A - Combustion chamber of internal combustion engine - Google Patents

Abstract

PURPOSE:To generate a strong gas flow in the air-fuel mixture on the center portion of a combustion chamber by positioning the summit of a conical surface serial to the valve seat of an intake valve outside the combustion chamber from the center line of the valve axis of the intake valve, on the planar projection of a combustion chamber. CONSTITUTION:The roof wall surface on the cylinder head 4 side of a combustion chamber 18 is formed out of the parts of respective conical surfaces 9a, 9b, 10a, 10b extending approximately in the tangential direction from the seat surfaces of respective valves, centering respective intake valve seats 6 and respective exhaust valve seats 8. In the conical surface 9a on intake valve 13a side, a summit P1 is positioned on the line of the center line V1 passing through a valve axis. On the other hand, in the conical surface 9b on intake valve 13b side, a summit P2 is positioned outwards more than the center line V2 passing through the valve axis. By this constitution, the center line C2 of the conical surface and a center line V2 cross each other, and the conical surface 9b is established so that it inclines towards the center of the combustion chamber 18 to direct a main intake air flow from the intake valve 13b in the direction of an ignition plug 17. It is thus possible to generate a strong gas flow in the central portion of the combustion chamber 18.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in the structure of a combustion chamber to improve the combustion efficiency of a combustion engine.

(Prior art) In order to increase the efficiency of intake air flowing into the combustion chamber of an internal combustion engine,
There is a proposal to form a combustion chamber wall surface by a part of the spherical surface in contact with the seat surface (contact surface) of the intake valve seat, thereby smoothing the flow of intake air flowing into the combustion chamber from the gap between the intake valve and the intake valve seat. (Utility Model Publication No. 51-21203).

By the way, in an engine that has two intake valves in each combustion chamber, when generating intake swirl in the cylinder mainly with the aim of improving combustion in the partial load range, it is common to have each intake valve on the same side with respect to the center of the cylinder. Because of this arrangement, the intake air flowing into the combustion chamber from each intake valve collides head-on with each other half way around the cylinder's inner circumference, making it difficult to maintain a swirl (lateral swirl) along the cylinder's inner circumference. Therefore, the swirl is mainly a so-called vertical swirl in the direction of movement of the piston.

This vertical swirl is caused by the intake air flowing diagonally downward into the combustion chamber from the intake port as the piston descends, passes through the bottom surface of the opposing exhaust valve, and then hits the cylinder inner wall surface and the top surface of the piston, creating a vertical swirl. The flow is upward as shown.

(Problem to be Solved by the Invention) However, the main flow of intake air that flows through the gap between the intake valve and the intake valve seat and flows along the combustion chamber wall surface and passes through the lower surface of the exhaust valve is caused by unevenness on the wall surface on the exhaust valve side. etc., the flow was likely to be obstructed, and the vertical swirl was likely to attenuate in a short period of time.

Also, due to the inertial force of the intake air, vertical swirls tend to form on the extension line of the intake port, especially in types with two intake valves, because the spark plug is placed in the center between the parallel intake ports. Strong vertical swirl is difficult to generate near the ignition plug, and as a result, the flame propagation speed is slow immediately after ignition by the ignition plug, and the tendency is for vertical swirl to not necessarily contribute efficiently to shortening combustion time. There was also.

The present invention aims to solve such problems.

(Means for Solving the Problems) Therefore, the present invention provides an intake valve and an exhaust valve in the combustion chamber, and makes at least the intake ports unevenly located from the center of the combustion chamber, while
An ignition plug is arranged approximately in the center of the combustion chamber, and a conical surface connected to the valve seat of the intake valve forms a part of the wall surface of the combustion chamber, and the apex of this conical surface is the intake air point on the planar projection of the combustion chamber. The valve is configured to be located outside the combustion chamber with respect to the center line of the valve shaft.

(Function) The intake air flowing into the combustion chamber from the intake valve is guided in many flows from the annular gap with the intake valve seat along the conical surface of the combustion chamber wall that is connected to the annular gap.

The flow along the conical surface does not generate vortices because the inflow angle remains unchanged, and maintains high intake air filling efficiency even in high engine speed ranges.

On the other hand, the main flow of intake air flowing into the combustion chamber from the intake port is
The air tries to flow downward along the conical surface, but since the apex of the conical surface on the intake valve side is outside the valve axis center line and the conical surface is inclined, the intake air flowing from the intake port is It is guided by a conical surface and directed toward the center of the combustion chamber.

Therefore, the vertical swirl caused by the main flow of intake air passes through the lower surface of the spark plug in the center of the combustion chamber, causing a strong gas flow in the air-fuel mixture in the center of the combustion chamber.

Therefore, flame propagation immediately after ignition by the spark plug is promoted by this gas flow, achieving rapid combustion with a high initial combustion rate, and greatly improving combustion efficiency.

(Example) An embodiment of the present invention will be described below based on the drawings.

In the first embodiment shown in FIGS. 1 and 2, 4 is a cylinder head, 11 is a cylinder block, 12 is a piston, and a combustion chamber 18 is defined between the lower surface of the cylinder head 4 and the upper surface of the piston 12. will be accomplished.

An ignition plug 17 is attached to the cylinder head 4, located at the center of the ceiling wall surface of the combustion chamber 18, and two intake valves 13m, 13b and two exhaust valves 14 are located around this.
m, 14b are arranged.

As shown in the plan view of FIG. 2, each intake valve 13a, 13b
The exhaust valves 14m and 14b are located on opposite sides of the cylinder row centerline, and each pair of intake valves 1
3&, 13b and exhaust valves 14a, 14b are arranged to face each other.

Each intake valve 13a, 13b communicates with an intake port 5 formed in parallel on the same side of the cylinder head 4 with the cylinder row centerline as a boundary, and similarly exhaust valves 14a, 14b.
It also communicates with the parallel exhaust port 7.

The ceiling wall surface on the cylinder head side of the combustion chamber 18 is
Conical surfaces 9a, 9b and 10a, 10 extending substantially tangentially from the seating surfaces of each intake valve seat 6 and each exhaust valve seat 8
It is formed by a part of b.

In this embodiment, the apex P of the conical surface 9a on the intake valve 13a side is located on the center line vl passing through the valve shaft (approximately coincident with the intake port axis), but the conical surface 9b on the intake valve 13b side , the apex P2 is located outside the center line V2 passing through the valve shaft, that is, the cone center line C2 connecting the apex of the cone and the center of the bottom intersects the center line ■2, and the cone surface 9b is located in the combustion chamber. It is set to be inclined toward the center, and directs the main flow of intake air from the intake valve 13b toward the spark plug 17.

Squish areas 15 and 16 are formed around the combustion chamber 18 and are flush with the lower surface of the cylinder rad 4.

The system is constructed as described above, and its operation will be explained next.

Intake air from intake port 5 is passed through intake valves 13m and 13b.
When it opens, it flows into the combustion chamber 18 from the annular gap with the intake valve seat 6, and the main flow flows into the conical surface 9 connected to the intake valve seat 6.
a, 9b.

The flow of intake air along these conical surfaces 9a and 9b flows smoothly without generating vortices, and serves to increase intake air filling efficiency even in a high speed rotation range.

Incidentally, the main flow of the intake air flows along the conical surfaces 9m and 9b to the respective intake valves 13m and 1, depending on the inclination angle of the intake port 5.
3b and flow toward the lower surfaces of the exhaust valves 14a, 14b facing each other.

However, since the conical center line of the conical surface 9b on the side of one intake valve 13b is inclined toward the center of the combustion chamber, the intake air flow does not go straight toward the lower surface of the exhaust valve 14b facing the other side, but toward the center of the combustion chamber. The spark plug 17 is deflected downward.

Therefore, the intake air flowing into the combustion chamber from each of the intake valves 13m and 13b causes a vertical swirl in which at least one of them passes below the spark plug 17, and the part of the spark plug 17 that was conventionally located between the two swirls , can form a strong swirl.

As a result, when ignition is performed by the spark plug 17 near compression top dead center, the flame immediately after ignition quickly propagates based on the strong gas flow caused by the swirl, which results in a high initial combustion rate. Achieves efficient combustion.

Next, the embodiment shown in FIG. 3 will be explained.
By forming the guide slope 25 with a large conical surface apex angle in the region of the conical surface 9b around b toward the ignition plug 17, the flow of intake air toward the ignition plug 17 is made even smoother. , the vertical swirl across the ignition plug 19 is strengthened.

Furthermore, the embodiment shown in FIG. 4 has a conical surface 9b on the side of the intake valve 13b.
In addition, the conical surface 10m on the exhaust valve 14a side is also tilted to strengthen the vertical swirl toward the center of the combustion chamber.

The center line C1 of the conical surface 10m is the center line C2 of the conical surface 9b.
tilted so that it is parallel to

By doing this, the flow of intake air from the intake valve 13b during pulp overlap is made easier to direct toward the exhaust valve h side, and the inertia is used to direct the flow of intake air toward the center of the combustion chamber during the intake stroke. It's about pointing.

(Effects of the Invention) As described above, according to the present invention, the intake air flowing into the combustion chamber from the intake valve is smoothly guided without creating a vortex or the like along the conical surface of the combustion chamber wall that connects to the intake valve seat. is,
While maintaining sufficiently high intake air filling efficiency even in high-speed rotation ranges, the apex of the conical surface on the intake valve side is located outside the valve shaft centerline and the conical surface is tilted towards the center of the combustion chamber, so The incoming intake air is guided by the conical surface and directed toward the center of the combustion chamber, and as a result, the vertical swirl passes under the spark plug in the center of the combustion chamber, creating a strong gas flow in the air-fuel mixture in the center of the combustion chamber. Therefore, flame propagation immediately after ignition by the spark plug is promoted by this gas flow, and combustion efficiency can be significantly improved by rapid combustion with a high initial combustion rate.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view (A-AWr plane in FIG. 2) showing a first embodiment of the present invention, FIG. 2 is a plan view, and FIG. 3 is a plan view showing a second embodiment. FIG. 4 is a plan view showing the third embodiment. 4... Cylinder head, 5... Intake port, 6...
・Intake valve seat, 8...Exhaust valve seat, 9 m, 9
b... Conical surface, 10a, 10b... Conical surface, 11
...Cylinder block, 12...Piston, 13a
, 13b...intake valve, 14a, 14b...exhaust valve,
17... Spark plug 518... Combustion chamber. Figure Figure Figure 1 b b

Claims (1)

[Claims] An intake valve and an exhaust valve are provided in the combustion chamber, and at least the intake port is located unevenly from the center of the combustion chamber, while an ignition plug is placed approximately in the center of the combustion chamber, and a conical surface connected to the valve seat of the intake valve is used to facilitate combustion. An internal combustion engine characterized in that the conical surface forms a part of a chamber wall surface and is configured such that the apex of this conical surface is located on the outside of the combustion chamber with respect to the valve axis center line of the intake valve on a plane projection of the combustion chamber. combustion chamber.