JP2524124Y2 - 4-stroke engine intake passage - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-stroke engine suction passage formed in a cylinder head.

[0002]

2. Description of the Related Art An intake passage and an exhaust passage are formed in a cylinder head of a four-stroke engine.
It is introduced from the side of the cylinder head in a direction substantially perpendicular to the cylinder axis, curved in a direction substantially parallel to the cylinder axis, and opens to the combustion chamber. Most of the cross-sectional shapes are circular or elliptical as shown in FIG. That is, the distal side A and the centripetal side B, which are curved from the axis O, are usually symmetrical.

In such an intake passage, when fuel gas flows, the centrifugal force generated by the curved shape causes the centrifugal side A of the curve to be denser than the centripetal side B, and does not flow uniformly. Therefore, there has been a problem that the flow resistance is increased, the efficiency of suction into the cylinder is affected, and it is difficult to increase the output.

[0004]

As described above, in the intake passage of the conventional four-stroke engine, the density of the fuel gas flowing between the centrifugal side and the centripetal side of the curved portion has a density difference due to centrifugal force. There was a problem that the output was affected as a resistance.

The present invention improves this point by improving the cross-sectional structure of the branched suction passage to make the gas density uniform and to reduce the suction resistance caused by the non-uniform density to improve the output. The purpose of the present invention is to provide an intake passage for a four-cycle engine.

[0006]

In order to achieve the above-mentioned object, the intake passage of the four-stroke engine of the present invention is introduced from a direction substantially perpendicular to the cylinder axis, and extends in a direction substantially parallel to the cylinder axis. In the intake passage of the cylinder head, which branches into each branch passage through the branch wall while being curved and opens to the combustion chamber, the cross-sectional shape of each branch passage connected to the intake port opened and closed by the intake valve is defined by one side of the branch wall. And a substantially triangular shape in which the centrifugal side of the curve from the passage axis is enlarged in the width direction and the centripetal side is reduced in the width direction.

[0007]

The following effects are obtained by adopting the above configuration. That is, in the curved suction passage, more fuel gas flows to the centrifugal side of the curve due to centrifugal force,
Since the cross-sectional structure of each branch passage of the suction passage that opens to the combustion chamber while being curved is formed in a substantially triangular shape, the gas density in the cross section of the passage is averaged over the entire surface. For this reason, the gas flow resistance decreases, the suction efficiency increases, the volumetric efficiency to the cylinder improves, and the output increases.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention.

FIGS. 3 and 4 show a suction passage of a four-stroke engine, which has two suction ports.

The suction passage 1 is introduced from a side surface of the cylinder head 2 from a direction substantially perpendicular to the cylinder axis XX, and is curved in a direction (angle α) substantially parallel to the axis XX. And opens to the upper part of the combustion chamber 3. An intake valve is interposed at the open end. Xa-X indicates the axis of the intake valve, and is inclined at an angle α with respect to the cylinder axis XX together with the axis Xb-X of the exhaust valve. Xc-X is a curved axis of the suction passage 1.

FIG. 1 is a cross-sectional view of each of the branch passages 1b, 1b of the suction passage 1 branched through a branch wall 5 serving as a partition wall, taken along the line II of FIG. The centrifugal side A, which is curved from the axis Xc-X with the branch wall 5 as one side, is enlarged in the lateral width direction, and the centripetal side B is set to an inverted triangular cross-sectional structure reduced in the lateral width direction. Chain lines 4b, 4b shown in FIG. 1 are branch passages 4b, 4b of the conventional suction passage.
The cross-sectional structure of the suction passage 1 is different from the branch passages 4b, 4b of the conventional suction passage.
Are set so that the cross-sectional area and the vertical width are almost the same.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 3 of the passage 1a at the introduction portion before the branch portion of the suction passage 1. Similarly to the above, the distal side A is curved from the axis Xc-X before the branch portion. Is enlarged in the width direction so that one side of the centrifugal side is the longest,
Are set to have an inverted trapezoidal shape reduced in the width direction. 4a is a cross section of the suction passage before the conventional branch portion.

Since the fuel gas flowing through the suction passage 1 is curved as described above, a larger amount of fuel gas tends to collect on the centrifugal side under the action of centrifugal force. However, the suction passage 1
Since each of the passages 1a and 1b branched from the cross section has a larger cross-sectional area on the centrifugal side A of the curve than the centripetal side B, the gas density is corrected to be substantially uniform over the entire cross-sectional area.

Accordingly, there is no increase in the inflow resistance due to the non-uniform density, and the suction passage 1 has good suction efficiency. Since the cross-sectional area and the vertical width do not increase as compared with the conventional suction passage, the engine output can be improved without increasing the size of the cylinder head.

Each branch passage 1 of the branched suction passages
Since the cross-sectional structures of b and 1b are substantially triangular, the flow rate of the air-fuel mixture flowing on the centrifugal side of each of the branch passages 1b and 1b of the suction passage is increased as a whole, and between the air-fuel mixture flowing on the centripetal side. A flow difference is generated, and a vertical vortex is generated in the combustion chamber 3 of the cylinder according to the flow difference, so that the air-fuel mixture can be efficiently injected into the combustion chamber.

[0016]

The intake passage of the four-stroke engine according to the present invention is introduced from a direction substantially perpendicular to the cylinder axis, and is bent in a direction substantially parallel to the cylinder axis while branching through the branch wall. In the suction passage of the cylinder head that branches into the passage and opens to the combustion chamber, the cross-sectional shape of each branch passage connected to the intake port opened and closed by the intake valve has the branch wall as one side, and is curved on the centrifugal side from the passage axis. Is formed in a substantially triangular shape with the centerline side reduced in the width direction, so that the branch wall can be used as a partition wall and shared by each branch passage, and the density of the inflowing fuel gas can be increased. Is maintained uniformly in the entire cross-sectional area of each branch passage, the suction resistance is reduced, the suction efficiency is increased, and the engine output can be increased.

Further, since the cross-sectional structure of each branch passage of the suction passage is formed in a substantially triangular shape with a wide curved centrifugal side, the mixing resistance flowing along the centrifugal side of each branch passage is combined with low suction resistance. The flow rate of the gas increases as a whole, and a flow difference occurs between the mixture and the mixture flowing on the centripetal side. A vertical vortex is generated in the combustion chamber of the cylinder due to the difference in the flow rate, and the mixture is efficiently filled in the combustion chamber. be able to.

[Brief description of the drawings]

FIG. 1 is a perspective view of an intake passage according to an embodiment of the present invention.
FIG.

FIG. 2 is a cross-sectional view of the suction passage according to the embodiment, taken along the line II-II in FIG. 3;

FIG. 3 is a vertical side view of a suction passage according to an embodiment of the present invention.

FIG. 4 is a plan view taken along the line III-III in FIG. 3;

FIG. 5 is a sectional view of a conventional suction passage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intake passage 1, 1a, 1b Branch passage 2 Cylinder head 3 Combustion chamber 5 Branch wall

Claims (1)

(57) [Scope of request for utility model registration] 1. A cylinder head which is introduced from a direction substantially perpendicular to a cylinder axis, is curved in a direction substantially parallel to the cylinder axis, branches into respective branch passages via a branch wall, and opens into a combustion chamber. In the suction passage, the cross-sectional shape of each branch passage connected to the intake port opened and closed by the intake valve has the branch wall as one side, and the centrifugal side curved from the passage axis is enlarged in the width direction, and the centripetal side is expanded in the width direction. An intake passage for a four-stroke engine, wherein the intake passage is formed in a substantially triangular shape that is reduced in size.