JP2737083B2 - 4 cycle engine - Google Patents

Description

The present invention relates to a four-stroke engine.

[Conventional technology]

In recent four-stroke engines, there is a tendency to increase the number of valves, and by increasing the opening area of the valves, the efficiency of air-fuel mixture intake is increased, thereby improving the output.

[Problems to be solved by the invention]

By the way, in a four-stroke engine having a normal cylindrical piston, the mechanism is significantly complicated, and the arrangement of three intake valves per cylinder is the limit, and further improvement of the intake efficiency is aimed at. It is difficult.

For this reason, conventionally, the piston is configured in an elliptical column shape,
There is provided a four-stroke engine in which four intake valves are arranged side by side in the major axis direction of the ellipse.

However, in the engine as described above, since the piston has an elliptical column shape, manufacturing and processing operations of the piston and the cylinder are extremely complicated.

An object of the present invention is to provide a four-stroke engine capable of improving the suction efficiency without requiring complicated manufacturing and processing operations in view of the above-mentioned circumstances.

[Means for solving the problem]

In the present invention, each piston (1) of the cylinders adjacent to each other is provided.
A main combustion chamber (13) is formed at a portion opposed to the top, and a portion on one side of a center plane (C) connecting the axes of the adjacent pistons (1) in each main combustion chamber (13). An exhaust passage (4d) is opened at the opening, and an exhaust valve (7) for opening and closing between the opening and the main combustion chamber (13) is arranged in each of the openings, and a portion on the other side of the center plane (C). A main intake passage (4c) is opened in the main combustion chamber (1).
In the four-stroke engine, an intake valve (6) for opening and closing between the main combustion chamber (3) and an ignition plug mounting hole (12) is provided at the center of each main combustion chamber (13). A sub-combustion which constantly communicates the main combustion chambers (13) with each other at a position deviated toward the intake valve (6) from a center plane (C) connecting the piston axes between the chambers (13). Chamber (14) and the main intake passage (4
c) branch the sub-intake passage (4f) from at least one of the sub-combustion chambers (1f).
4) An opening is provided at a portion on the other side deviated toward the intake valve (6) from a center plane (C) connecting the piston axes, and the opening is provided between the opening and the sub-combustion chamber (14). A sub intake valve (8) for opening and closing the valve is provided.

[Action]

According to the above configuration, the air-fuel mixture is sucked into the adjacent main combustion chamber (13) communicated by the sub-combustion chamber (14) through the main intake passage (4c) and the sub-intake passage (4f). .

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing examples.

FIGS. 1 to 4 conceptually show a main part of a four-stroke engine according to the present invention, and exemplify a DOHC engine mounted on a motorcycle.

As shown in FIGS. 2 and 3, this engine
It has a pair of pistons 1, 1 adjacent to each other. The pistons 1 and 1 have the same cylindrical shape and are fitted in sleeves 3 and 3 embedded in the cylinder block 2, respectively. The sleeves 3, 3 have a cylindrical shape, and upper ends of the peripheral surfaces thereof are connected to each other. The sleeves 3, 3 have a substantially figure-eight shape on the cylinder head mounting surface 2a of the cylinder block 2. Although not explicitly shown in the drawing, the pair of pistons 1 and 1 are connected to the same-phase crankpins of the crankshaft via connecting rods.

As shown in FIG. 1, a cylinder head 4 applied to this engine has a pair of recesses on a cylinder block mounting surface 4a.
4b, 4b. The recesses 4b, 4b are formed at portions of the cylinder block 2 opposed to the tops of the pistons 1, 1, respectively. Inside the recesses 4b, one end opening of a main intake port (main intake passage) 4c and an exhaust port (exhaust passage) are provided. 4d has two openings at one end, and has ignition plug mounting holes 12, 12 for mounting an ignition plug (not shown) at the center of each.

The main intake ports 4c, 4c, 4c, 4c and the exhaust ports 4d, 4d, 4d, 4d each have an opening at one end of the recess 4b, 4b.
Center plane C connecting the axes of adjacent pistons 1 and 1
Are arranged along the longitudinal direction of the cylinder head 4 in a row on each of a portion on one side and a portion on the other side.
Are open on the opposite side walls. As is clear from the figure, the main intake ports 4c, 4c, 4c, 4c and the exhaust ports 4d, 4d, 4d, 4d have their respective other ends at the respective concave portions 4b,
It joins each one corresponding to 4b. Further, vaporizers 5, 5 having the same diameter as each other corresponding to the recesses 4b, 4b are connected to the other ends of the main intake ports 4c, 4c, 4c, 4c, respectively.

In addition, two intake valves 6 and two exhaust valves 7 are provided in the recesses 4b, 4b, respectively.

The intake valves 6, 6, 6, 6 are connected to the main intake ports 4c, 4c, 4c,
The opening 4c is disposed at a position for opening and closing, and is simultaneously opened and closed at the same time by an intake valve cam shaft 9 disposed on the cylinder head 4.

The exhaust valves 7, 7, 7, 7 are connected to the exhaust ports 4d, 4d, 4d,
The opening 4d is arranged at a position for opening and closing, and is simultaneously opened and closed at the same time by an exhaust valve cam shaft (not shown).

Further, the cylinder head 4 has a connecting recess 4e on the cylinder block mounting surface 4a. This connecting recess 4e
Is closer than the center plane C connecting the axes of the pistons 1 and 1 between the adjacent recesses 4b and 4b.
The pair of recesses 4b, 4b communicate with each other.

One end of a sub intake port (sub intake passage) 4f is opened in the connection concave portion 4e. The sub-intake port 4f extends from the main intake port 4c, 4c that opens to one of the recesses 4b, and is the same as one end opening of the main intake port 4c, 4c, 4c, 4c that communicates with each of the recesses 4b, 4b. Is opened at a position on the array.

Further, a sub intake valve 8 is provided in the connection recess 4e. As shown in FIG. 4, the auxiliary intake valve is disposed at a position that opens and closes the opening of the auxiliary intake port 4f, and the intake valve cam that opens and closes the intake valves 6, 6, 6, 6 described above. By the shaft 9, these intake valves 6, 6,
It will be opened and closed at the same time as 6,6. In addition,
Reference numeral 10 in FIG. 4 denotes a swing arm type hydraulic lash adjuster.
The same thing is provided in 6,6,6,6 and the exhaust valves 7,7,7,7. Reference numeral 11 in FIGS. 3 and 4 denotes
This is a valve recess for the auxiliary intake valve provided at the connection between the sleeves 3,3.

In the above-described engine, as shown in FIG. 2, when the cylinder head 4 is mounted on the cylinder block 2, the pistons 1 occupying the recesses 4b, 4b, the inner peripheral surfaces of the sleeves 3, 3 and the top dead center are formed. , 1 by the main combustion chamber 13,
13 is defined, and a sub-combustion chamber 14 is provided between the main combustion chambers 13, 13 by the connecting portion of the connecting recess 4e and the sleeves 3, 3 for constantly communicating the main combustion chambers 13, 13 with each other. Is done.

Now, the intake valves 6, 6, 6, 6 in the main combustion chambers 13, 13 are operated by the intake valve cam shaft 9, and the main intake port
Openings of 4c, 4c, 4c, 4c are opened and pistons 1, 1
Is moved downward, the main intake ports 4c, 4c, 4c, 4c, 4c,
The air-fuel mixture is sucked from the vaporizers 5, 5 via 4c.

At this time, in the sub-combustion chamber 14 communicating with the main combustion chambers 13, 13, the intake valves 6, 6, 6, 6 and the sub-intake valve 8
Is actuated to open the opening of the sub-intake port 4f, and the pistons 1, 1 are in a negative pressure state due to the downward movement.

Therefore, the inside of the main combustion chambers 13,13 and the sleeves 3,3
The air-fuel mixture is also drawn into the interior through the sub-intake port 4f and the sub-combustion chamber 14, so that the air-fuel mixture suction efficiency is greatly improved and the engine output is improved.

In the above embodiment, the main combustion chambers 13 and 13 of the two cylinders are used.
Are illustrated as communicating with each other by the sub-combustion chamber 14, but in the present invention, the main combustion chambers of three or more cylinders may be communicated with each other. Further, although the cylinders communicating the main combustion chambers 13 and 13 exemplify one set of engines, an engine composed of a plurality of sets of cylinders may be used. Furthermore, although a DOHC engine mounted on a motorcycle is illustrated, the invention is not necessarily limited thereto.

In the above embodiment, one sub-intake port 4f is opened in the sub-combustion chamber 14 and one sub-intake chamber 4 is opened.
Although one sub intake valve 8 is provided, in the present invention, a plurality of sub intake ports 4f and sub intake valves 8 may be provided. Further, in the sub combustion chamber 14, only the sub intake port 4f is opened, and only the sub intake valve 8 is provided. In the four-stroke engine according to the present invention, in addition to these, the sub combustion chamber 14 The sub exhaust port may be opened, and the opening of the sub exhaust port may be opened and closed by the sub exhaust valve.

〔The invention's effect〕

As described above, according to the four-stroke engine according to the present invention, the suction efficiency can be improved by using the cylindrical piston, so that the output can be improved by a simple manufacturing and processing operation.

In addition, since the sub intake passage is formed by branching off from the main intake passage, the main intake passage and the air-fuel mixture generation device such as a carburetor can be used in common, thereby suppressing an increase in engine width and cost. be able to.

[Brief description of the drawings]

FIG. 1 is a bottom view conceptually showing a cylinder head portion applied to the four-stroke engine according to the present invention, and FIG. 2 is a cross-sectional view conceptually showing a main part of the four-stroke engine according to the present invention. FIG. 3 is a perspective view conceptually showing a cylinder block portion applied to the four-stroke engine according to the present invention, and FIG. 4 is an enlarged sectional view taken along the line IV-IV in FIG. 1 ... Piston, 4c ... Main intake port, 4d ... Exhaust port, 4f ... Sub intake port, 6 ...
Intake valve, 7 ... Exhaust valve, 8 ... Sub intake valve,
12: spark plug mounting hole, 13: main combustion chamber, 14: sub-combustion chamber, C: center plane connecting the axes of the pistons.

Claims (1)

(57) [Claims] 1. A main combustion chamber (13) is formed at a position facing the top of each piston (1) of adjacent cylinders, and the adjacent piston (1) is formed in each main combustion chamber (13).
An exhaust passage (4d) is opened at a position on one side of the center plane (C) connecting the axes of the exhaust valves, and an exhaust valve (7) that opens and closes the main combustion chamber (13) is provided at the opening. On the other hand, a main intake passage (4c) is opened at a portion on the other side of the center plane (C), and an intake valve (6) that opens and closes the main combustion chamber (13) is provided at the opening. In a four-stroke engine provided with a spark plug mounting hole (12) at the center of each main combustion chamber (13), the piston shaft center is located between the main combustion chambers (13). A sub-combustion chamber (14) is formed at a position deviated to the intake valve (6) side from the connecting central plane (C), so that the main combustion chambers (13) are always in communication with each other. 4c), the sub intake passage (4f) is branched from at least one of the sub intake passages (4f). The sub-combustion chamber (14) has an opening at the other side deviated toward the intake valve (6) from a center plane (C) connecting between the piston axes, and the sub-combustion chamber (14) is provided at the opening. A four-stroke engine characterized by having an auxiliary intake valve (8) that opens and closes between the two intake valves.